OFFICE OF THE FEDERAL COORDINATOR FOR

METEOROLOGICAL SERVICES AND SUPPORTING RESEARCH

U.S. DEPARTMENT OF COMMERCE/ National Oceanic and Atmospheric Administration

PROCEEDINGS

OF THE

2nd International Conference

on Volcanic Ash and

Aviation Safety

June 21-24, 2004

Hilton Alexandria Mark Center Hotel

Alexandria, Virginia (USA)
THE FEDERAL COMMITTEE FOR

METEOROLOGICAL SERVICES AND SUPPORTING RESEARCH (FCMSSR)

VADM CONRAD C. LAUTENBACHER, JR., USN (RET.) 

Chairman, Department of Commerce

DR. KATHIE OLSEN

Office of Science and Technology Policy

DR. RAYMOND MOTHA 

Department of Agriculture

BRIG GEN DAVID L. JOHNSON, USAF (RET.)

Department of Commerce

MR. ALAN SHAFFER

Department of Defense

DR. ARISTIDES PATRINOS

Department of Energy

DR. PENROSE C. (PARNEY) ALBRIGHT

Science and Technology Directorate

Department of Homeland Security

DR. ROBERT M. HIRSCH

Department of the Interior

MR. RALPH BRAIBANTI

Department of State

MR. RANDOLPH LYON

Office of Management and Budget

MR. NORMAN FUJISAKI (Acting)

Department of Transportation

MR. DAVID MAURSTAD (Acting)

Federal Emergency Management Agency

Department of Homeland Security

DR. GHASSEM R. ASRAR

National Aeronautics and Space

 Administration

DR. MARGARET S. LEINEN

National Science Foundation

MR. PAUL MISENCIK

National Transportation Safety Board

MR. JOHN W. CRAIG

U.S. Nuclear Regulatory Commission

DR. GARY FOLEY

Environmental Protection Agency

MR. SAMUEL P. WILLIAMSON

Federal Coordinator 

MR. JAMES B. HARRISON, Executive Secretary

Office of the Federal Coordinator for

Meteorological Services and Supporting Research

THE INTERDEPARTMENTAL COMMITTEE FOR

METEOROLOGICAL SERVICES AND SUPPORTING RESEARCH (ICMSSR)

MR. SAMUEL P. WILLIAMSON, Chairman

Federal Coordinator

MR. THOMAS PUTERBAUGH

Department of Agriculture

MR. JOHN E. JONES, JR.

Department of Commerce

RADM STEVEN J. TOMASZESKI, USN

United States Navy

Department of Defense

BRIG GEN THOMAS E. STICKFORD, USAF

United States Air Force

Department of Defense

MR. RICKEY PETTY

Department of Energy

MS. NANCY SUSKI

Science and Technology Directorate

Department of Homeland Security

MR. LEWIS T. MOORE

Department of the Interior

MS. REGINA MCELROY

Federal Highway Administration

Department of Transportation

MS. LISA BEE

Federal Aviation Administration

Department of Transportation

DR. JONATHAN M. BERKSON

United States Coast Guard

Department of Homeland Security

MR. JEFFREY MACLURE

Department of State

DR. S. T. RAO

Environmental Protection Agency

MR. JOHN GAMBEL

Federal Emergency Management Agency

Department of Homeland Security

DR. RAMESH KAKAR

National Aeronautics and Space

 Administration

DR. JARVIS MOYERS

National Science Foundation

MR. DONALD E. EICK

National Transportation Safety Board

MS. LETA A. BROWN

U.S. Nuclear Regulatory Commission

MS. ERIN WUCHTE

Office of Management and Budget

MR. JAMES B. HARRISON, Executive Secretary

Office of the Federal Coordinator for

Meteorological Services and Supporting Research
OFFICE OF THE FEDERAL COORDINATOR 

FOR METEOROLOGICAL SERVICES AND SUPPORTING RESEARCH 

8455 Colesville Road, Suite 1500 

Silver Spring, Maryland 20910 

301-427-2002 

www.ofcm.gov 

PROCEEDINGS 

OF THE 

2nd International Conference on Volcanic Ash and Aviation Safety 

June 21-24, 2004 

Hilton Alexandria Mark Center Hotel 

Alexandria, Virginia (USA) 

Washington, DC 

November 2004 
ii
iii

FOREWORD 

In February 1997, the White House Commission on Aviation Safety and Security 

recommended a national goal for government and industry of reducing the fatal aviation 

accident rate by 80 percent in 10 years. The National Aviation Weather Program Council 

adopted the 80 percent reduction goal and in February 1999 the National Aviation 

Weather Initiatives document was published as the next major step in coordinating the 

many federal and nonfederal programs relevant to improving aviation safety. Because of 

the serious threat posed by volcanic ash and other airborne hazardous materials, these 

were identified as one of the principal service areas for the aviation weather program. 

Although there have been no fatal accidents caused by encounters with volcanic ash, 

there have been close calls with aircraft experiencing in-flight engine failures. 

Fortunately, these aircraft were able to land safely, but in some instances the cost to 

repair the aircraft was in the millions of dollars. The fact that there have not been recent 

incidents or accidents speaks to the work of the Volcanic Ash Advisory Centers around 

the world but there is more we can do to ensure that encounters are reduced to zero and 

that there is never a fatal accident resulting from a volcanic ash encounter. 

This document summarizes the proceedings of the 2nd International Conference on 

Volcanic Ash and Aviation Safety and provides a roadmap for building on our successes 

in aviation safety over the next decade. I wish to thank the U.S. Geological Survey, the 

National Oceanic and Atmospheric Administration, the Federal Aviation Administration, 

the National Aeronautics and Space Administration, the Smithsonian, the Air Line Pilots 

Association, the Meteorological Service of Canada, the International Association of 

Volcanology and Chemistry of the Earth’s Interior, and the Tenix Corporation for their 

sponsorship of this conference. In addition, I want to thank the Director of the National 

Museum of Natural History, Smithsonian Institution, for his warm welcome at our 

reception and private viewing of the museum. Special thanks goes to the Working Group 

for Volcanic Ash, the conference planning committee, and to the colleagues from the 21 

countries, 15 airlines, 12 universities, 6 private corporations and other participants who 

were instrumental in making this conference a huge success.

 Sincerely, 

 Samuel P. Williamson 

 Federal Coordinator for Meteorological 

 Services and Supporting Research 
iv
v

TABLE OF CONTENTS 

FOREWORD ..................................................................................................................... iii 

TABLE OF CONTENTS.....................................................................................................v 

OPENING SESSION....................................................................................................... 1-1 

Conference Goals and Objectives 

Keynote Address and Invited Presentations 

The Honorable Ted Stevens (invited) 

Dr. James Mahoney 

Dr. Charles Grout 

RADM James Schear (USNR), Retired 

Mr. Ronald Birk 

Mr. Gianni Semenzato 

Letter from Senator Stevens 

PANEL DISCUSSIONS.................................................................................................. 2-1 

Panel 1: Airborne Volcanic Ash: Perspectives, 

Challenges, and Opportunities 

Panel 2: Education, Training, and Outreach 

PLENARY SESSIONS.................................................................................................... 3-1 

Session 1: Encounters, Damage, and 

Socioeconomic Consequences 

Session 2: The Volcanic Source - Eruption 

Monitoring and Reporting 

Session 3: Ash Cloud Observations, Modeling, 

and Forecasting 

Session 4: VAAC Operations and Capabilities 

Session 5: Aviation Industry Perspectives 
vi

BREAKOUT SESSIONS ................................................................................................ 4-1 

Session 1: Improving Volcanic Ash Cloud Detection 

Session 2: Improving Modeling Capabilities 

Session 3: Understanding the Socioeconomic Consequences 

Session 4: Improving Volcanic Eruption Reporting 

Session 5: Technology Transfer from Research into Operations 

Session 6: Improving VAAC Operational Capabilities 

Session 7: Meeting Aviation Needs 

REGIONAL BREAKOUT SESSIONS........................................................................... 5-1 

Session 8: North Asia Pacific 

Session 9: The Americas and the Caribbean 

Session 10: Europe, Africa, and the Middle East 

Session 11: South Asia Pacific 

CLOSING SESSION....................................................................................................... 6-1 

ICAO’s Commitment to Mitigating the Volcanic Ash Hazard 

 Mr. William Voss 

Conference Highlights 

Building on Our Successes in Aviation Safety for the Next Decade 

Next Steps 

APPENDIX A: AGENDA.............................................................................................. A-1 

APPENDIX B: ATTENDEES.........................................................................................B-1 

APPENDIX C: PAPERS .................................................................................................C-1 

Index of Papers (by Session) 

Index of Authors 
 1-1

OPENING SESSION 

Conference Goals and Objectives 

Goals of the Second International Conference on Volcanic Ash and Aviation Safety 

• Consolidate and communicate the substantial progress made in the technical, operational, and 

scientific aspects of ash hazard mitigation since the first international meeting in 1991. 

• Identify requirements and opportunities for further improvements in each component of the 

coordinated, international mitigation system. 

• Leverage the ongoing investment of effort and resources by the international programs, 

technology R&D partners, and the aviation industry to ensure the greatest return in reducing risks 

to safety and socioeconomic consequences. 

The Risk to Aviation from Airborne Volcanic Ash 

Airborne volcanic ash poses a serious threat to aviation, but this threat 

can be mitigated through the combined efforts of scientific specialists, the 

aviation industry, and air traffic control centers. More than 100 

commercial and military aircraft have unexpectedly encountered volcanic 

ash clouds in flight. The consequences of an aircraft flying into an ash 

cloud can include degraded engine performance (including flameout), loss of visibility, and failure of 

critical navigational and operational instruments. Several encounters have resulted in multiple engine 

failures, and disastrous crashes have been only narrowly averted. In addition to major repair costs from 

encountering a dense plume (up to $80 million in damages have occurred to a single aircraft), aircraft 

encountering less dense volcanic ash clouds have required increased maintenance of engines and external 

surfaces. 

The safest mitigation strategy is for aircraft to avoid flying into an ash plume. Avoidance requires 

knowing where an ash plume exists before entering it. Dispatchers, pilots, and air traffic controllers must 

be quickly informed of pre-eruptive volcanic activity, explosive eruptions, and the location and direction 

of ash plumes anywhere these may occur around the globe. On average, 

about 15 major explosive eruptions—those powerful enough to inject ash 

above 25,000 feet into the stratosphere—occur per year. The ash plume 

from a major eruption, such as Mt. Pinatubo in 1991, can affect aircraft 

thousands of miles downwind. When Mt. St. Helens erupted in 1980, the 

plume reached an altitude of 90,000 ft. in 30 minutes and was 50 miles 

wide. 

An International Problem that Requires an International Solution 

Volcanic ash is a worldwide aviation problem that demands an international solution. A volcanic “ring of 

fire” circles the Pacific basin from South and Central America through the Pacific Northwest and Alaska, 

and around to Kamchatka, Japan, Indonesia, the Philippines, and Micronesia. This region is often cited as 

having the greatest volcanic ash risk because of the number of active volcanoes and their proximity to 

major aviation routes. About 100 potentially dangerous volcanoes lie under air routes in the North Pacific 

region alone. Other regions of volcanic activity are in the Caribbean and Mediterranean basins and south 

Asia, as well as Iceland and the Azores in the Atlantic basin. Ash carried downwind from an eruption in 

any of these regions can endanger aircraft flying in its path. 

The International Civil Aviation Organization (ICAO) began adopting provisions in 1987 for volcanic ash 

warnings to be included in aviation SIGMETs. In 1998, ICAO established the International Airways 

Volcano Watch, which consists of nine Volcanic Ash Advisory Centers (VAACs) to provide an interface 

More than 100 commercial 

aircraft have had ash-encounter 

incidents. Damage to a single 

aircraft has been as high as $80 

million. 

In 15 hours, the Mt. St. Helens 

plume traveled 600 miles downwind. After 2 weeks, ash had 

circled the Earth. 
 1-2

between volcano observatories, meteorological agencies, and air traffic control centers. Each VAAC uses 

reports from volcano observatories and satellite imagery to track volcanic activity and ash clouds in its 

designated region. 

Improving the International System for Volcanic Ash Risk Mitigation 

The 1991 symposium on volcanic ash and aviation safety brought international stakeholders, as well as 

U.S. Federal agencies and many R&D partners, together for the first time. Since then, the nine VAACs 

have been established, along with channels for rapid communication of volcano eruption and plume 

movement information to the aviation community. Methods for observing and analyzing the indicators of 

an impending eruption have been improved. New satellite-based remote sensing techniques are being 

used or developed for both volcano monitoring and ash-cloud identification and tracking. 

Accurate, timely reporting of an eruption, including premonitory information about the build-up phase 

and real-time detection of the eruption, is an important component of mitigating the risk to aviation. 

Various physical and chemical signals, called “volcanic unrest,” are related to the rise of magma toward 

the Earth’s surface. Tracking these signals over periods of weeks to years before an eruption, combined 

with knowledge of a volcano’s eruptive history, allows volcanic unrest to be monitored and interpreted. 

Volcano observatories use this approach to forewarn, to the extent possible, of impending eruptions. 

Once an explosive eruption occurs, polar-orbiting and geosynchronous satellites can use radiometry, 

multispectral analysis, and other techniques to detect and track ash clouds. These satellite images provide 

snapshots in time of the location of airborne ash. Atmospheric dispersion models provide forecasts of 

where an ash cloud is headed, to give pilots, dispatchers, and controllers warning in advance. Airborne 

detection systems for volcanic gas and ash detection are being developed and tested. 

Just as important to risk mitigation as these technological advances is the operational experience of the 

aviation community—commercial carriers, pilots, air traffic controllers, flight service specialists, etc.—

with the still-evolving international system for detecting and communicating volcanic ash hazards. The 

time is right to bring all these stakeholders together again, to assess how the current system is operating 

and to focus attention on the critical areas for improvement. 

The Second International Conference on Volcanic Ash and Aviation Safety is designed to meet these 

objectives. Its plenary and breakout sessions cover the major components of volcanic ash hazard 

mitigation, progress in technology and operations, the needs of the aviation community, and future 

directions for coordinated efforts. Agenda topics for the 4-day conference include: 

• Physical damage to aircraft from encounters with volcanic ash clouds and the socioeconomic 

consequences of the volcanic ash hazard. 

• The volcanic source: operations and improvements in eruption monitoring and reporting. 

• Ash-cloud observations and forecasting: improving ash-cloud detection and modeling 

capabilities. 

• Operations and capabilities at the regional VAACs: improving VAAC communications and 

operational capabilities to meet world aviation safety needs. 

• Aviation industry perspectives: transferring technology from research into operations to meet 

aviation needs. 

• Education and outreach to pilots, air traffic controllers, dispatchers, the aviation industry, and the 

meteorological and communications support services to aviation. 

Airborne volcanic ash will persist as a serious aviation hazard. Mitigation strategies are working now but 

can and should be strengthened. The Second International Conference on Volcanic Ash and Aviation 
 1-3

Safety brings the scientific, technology development, and aviation communities together to consolidate 

and communicate the progress that has been made, identify requirements and opportunities for further 

improvements, and leverage the ongoing investment of effort and resources to ensure the greatest return 

in reducing the risks. 

Conference Objectives 

• Identify new operational needs/requirements and the research and development needed to satisfy 

those requirements. 

• Match operational and research and development needs/requirements to ongoing 

programs/projects to maximize partnership efforts. 

• Develop a roadmap for improved volcanic ash-related education, training, outreach, and decision 

tools. 

• Develop a framework for improved partnerships within the international volcanic ash community 

to leverage resources and capabilities across the spectrum of operations and research and 

development. 
 1-4
 1-5

Keynote Address and Invited Presentations 

Keynote Address:

The Keynote Address was to be given by the Honorable Ted Stevens, Senator, Alaska; 

however, Senator Stevens was unable to attend due to legislative obligations. A letter from 

Senator Stevens was read to the conference attendees (see p. 1-7). Dr. James R. Mahoney, 

Assistant Secretary of Commerce for Oceans and Atmosphere and National Oceanic and 

Atmospheric Administration (NOAA) Deputy Administrator, delivered the keynote address since 

Senator Stevens was not available. He discussed the role NOAA has played in the detection and 

monitoring of volcanic ash since the early 1980’s. This role was made more formal in 1988 for 

aviation safety with the near real-time ash monitoring, tracking, and composition of global 

volcanic activities. NOAA’s role also includes the operation of Meteorological Watch Offices, 

the development of numerical models for the forecasting of ash cloud motion, and the R&D of 

enhanced volcanic ash detection techniques for use in real-time operations. 

Invited Presentations: 

Dr. Charles G. Groat, Director of the U.S. Geological Survey (USGS) described the leading 

role of USGS in the global mitigation efforts to reduce the threat to aviation from volcanic ash, 

through an integrated program of volcanic monitoring and research, eruption reporting, and 

hazard education. Dr. Groat described the development of a color-coded notification alert 

scheme for volcanic ash warnings to the air carrier industry, which is now being recommended 

for worldwide use by the International Civil Aviation Organization (ICAO). With the 

establishment of the Alaska Volcano Observatory, the USGS has organized interagency 

communications procedures for volcanic eruption and airborne volcanic ash hazards in the North 

Pacific. 

Rear Admiral James P. Schear, U.S. Naval Reserve (Ret.), Federal Aviation Administration 

(FAA) Air Traffic Organization’s Vice President for Safety related that during the last two 

decades more than 80 jets suffered damage because of encounters with volcanic ash. These 

encounters resulted in hundreds of millions of dollars in damage to aircraft and unknown costs 

due to operational delays. The FAA has been a stakeholder in improving aviation weather 

services which has resulted in a safer and more efficient international airspace. RADM Schear 

stated that one of the principal goals is to “Increase the safety and capacity of the global civil 

aerospace system in an environmentally sound manner.” The FAA works closely with ICAO to 

adopt common international safety standards, air traffic procedures, and technologies. In 

addition, the FAA supports the operations of the Volcanic Ash Advisory Centers (VAACs) and 

the ICAO International Airways Volcano Watch Operations Group. RADM Schear also stated 

that more advanced countries need to help countries with limited resources that have active 

volcanoes where early detection is critical for flight safety. 
 1-6

Mr. Ronald J. Birk, Director of the Earth Science Applications Division, Office of Earth 

Science, National Aeronautics and Space Administration (NASA), spoke on NASA’s new vision 

of integrating Earth observations into decision-support tools for aviation and other applications 

of both national and international priority. NASA is working with the interagency Joint Planning 

and Development Office to produce a plan for a precise, continuous, and dynamic aviation 

weather digital database to support the aviation information infrastructure. Mr. Birk showed a 

movie, “A Vision of the Future,” and invited the global community to share in this vision. One 

dimension for accomplishing this vision is to extend the benefits of the sensors on NASA and 

NOAA Earth observation satellites to provide critical information on the early detection and 

transport of volcanic ash and gas. NASA and its partners benchmark practical uses of 

observations and predictions from Earth science models for decision-support tools that serve 

operational and policy decision makers. Mr. Birk discussed the Advanced Satellite Aviationweather Products project which is a partnership between NASA and FAA intended to integrate 

satellite observations into a wide range of graphical products, including volcanic ash. 

Mr. Gianni Semenzato, Senior Flight Inspector with the Ente Nazional per L’Aviazione Civile 

(Italian Civil Aviation Authority) described the Catania Fontanarossa Airport’s procedures for 

flight operations in the presence of volcanic ash. Based on information provided by ICAO, an 

organizational structure was identified of different civilian and military bodies involved in 

ensuring the operational condition for the airport during periods of strong volcanic activity. Mr. 

Semanzato spoke of the authorities involved, the monitoring and alarm capabilities, and the tasks 

and responsibilities of each group during an event. He concluded with the guidelines for 

evaluating the procedures. 

 1-8
 2-1

PANEL DISCUSSIONS 

Panel 1: Airborne Volcanic Ash: Perspectives, Challenges, and Opportunities 

Moderator: Dr. Elbert (Joe) Friday, WeatherNews Professor of Meteorology and 

 Founding Director of the Sasaki Applied Meteorology Research Institute, 

 University of Oklahoma 

Rapporteur: Mr. Floyd Hauth, Science and Technology Corporation

Panelists: Dr. Thomas P. Miller, Scientist Emeritus, USGS Alaska Volcano 

 Observatory 

 Dr. Louis Uccellini, Director, NOAA’s NWS National Centers for 

 Environmental Prediction

 Ms. Gloria Kulesa, Manager, Aviation Weather Research Program, FAA 

 Mr. Alan Shaffer, Director, Plans and Programs, Office of the Secretary 

 of Defense 

 Mr. Peter Chen, Environment Canada, Atmospheric and Climate Science 

 Directorate 

Synopsis: This panel focused on the progress of key actions/recommendations from the first 

conference; the current state of volcanic ash operational support and the status of supporting 

research; resource coordination and leveraging across the spectrum of operations and research; 

the transition of research into applications; and opportunities for the future, including efficient 

leveraging of the national and international technologies and research. Highlights included 

noting the good progress on volcanic ash initiatives since the first symposium and that 

partnerships and collaboration in the area of detection and warning are healthy. It was also noted 

that gaps continue in our understanding of the ash hazard and that some deficiencies continue 

with observations (analyses), modeling, and warning delivery. It was also noted that volcanic 

ash can reach commercial flight levels in as little as 5 minutes which poses a real challenge for 

the volcanic ash warning system. 

Dr. Thomas Miller: Dr. Miller summarized the composition of volcanic ash, the stringent 

requirement for timeliness of warnings, and information on the threat of encounters. He 

indicated that much progress had been made since the first symposium, but there is a need to 

continue efforts to improve the warnings. 

Dr. Louis Uccellini: Dr. Uccellini noted that the 5-minute requirement was hard to achieve but 

provided a good challenge to improve observations, modeling (forecasts), and delivery 

processes. Progress continues in model improvements, but the analysis process still requires too 

much time and delays warnings. 

Ms. Gloria Kulesa: Ms. Kulesa described FAA program investments in science and 

technology for aviation support. There are many partnerships in place, and collaborations 

continue to be healthy. 
 2-2

Mr. Peter Chen: Mr. Chen stated that volcanic ash warning requirements demand quick 

response and action for aviation safety. The providers of products and services need to continue 

to invest in modeling and supporting computation capability. There is also a need to determine 

the gaps in capabilities to deal with volcanic ash. He is also concerned about the possibility of 

higher false alarm rates when efforts push for achieving the 5-minute warning goal. 

Mr. Alan Schaefer: Mr. Schaefer described DOD activities and capabilities that support 

aviation operations threatened by volcanic ash. He also reported on progress supporting research 

projects. He indicated that satellites have the best potential to meet observation/detection needs. 

Navy centers currently issue tailored ash forecasts. 
 2-3

Panel 2: Education, Training, and Outreach 

Moderator: Dr. Gregory S. Forbes, Severe Weather Expert, The Weather Channel

Rapporteur: Mr. Donald Carver, FAA

Panelists: Ms. Cyndie Abelman, Meteorologist-In-Charge, NOAA’s NWS, 

 Oklahoma City, OK 

 Captain Albert Beerley, US Airways Airbus, US Airways/ALPA Training 

 Committee 

 Mr. John O’Brien, Director, Engineering and Air Safety Department, Air 

 Line Pilots Association 

 Mr. Saburo Onodera, Manager, Flight Crew Training Department, Japan 

 Airlines 

 Professor Eric Doten, Director of Center for Aerospace Safety/Security 

 Education, Embry-Riddle Aeronautical University 

Synopsis: The diverse panel discussed the education, training, and outreach activities within the 

university structure, the FAA, the airlines, as well as the international community. While many 

training/education programs exist, the panel highlighted the need for more training on the 

coordination of military and civil airspace during volcanic ash hazards; for continued 

development of bibliographies for training materials and case studies; and the need for outreach 

to agencies on understanding the risk and the reasons to provide resources for volcanic ash 

mitigation. 

Ms. Cyndie Abelman: Ms. Abelman stated that the FAA academy has intense weather training 

for flight service specialists. In the near future the training will include a volcanic ash hazards 

module. En route center controllers are assisted/advised by NWS personnel in Center Weather 

Service Units. 

Captain Albert Beerley: Captain Beerley noted that U.S. Airways trains on specific risk areas 

relative to their routes and terminals of operation. Training includes approach/departure 

procedures and sources of advisory/warning services. 

Mr. John O’Brien: Mr. O’Brien noted that the Air Line Pilots Association promotes 

operational awareness and procedures to enhance safety among its global membership. 

Members support programs plus outreach to agencies, controlling resources for research and 

development for better services. 

Mr. Saburo Onodera: Mr. Onodera stated that Japan Airlines has established a syllabus for 

training for each level of crew competencies, including volcanic ash avoidance and limits to 

operations. They emphasize route selection alternatives and simulations/drills. 

Professer Eric Doten: Dr. Doten stated that Embry-Riddle Aeronautical University has 130 

centers where they confer degrees in applied science for meteorology, including research 

opportunities. 
 2-4
3-1

PLENARY SESSIONS 

These sessions covered five areas: volcanic ash encounters; volcanic ash source; ash 

cloud observation, modeling, and forecasting; Volcanic Ash Advisory Center (VAAC) 

operations and capabilities; and aviation industry perspectives. The sessions consisted of 

both oral and poster presentations from the international community and set the stage for 

related breakout sessions. Papers for some presentations can be found in Appendix C. 

Session 1: Encounters, Damage, and Socioeconomic Consequences 

Session Chairs: Mr. Edward Miller, Air Line Pilots Association

 Mr. Leonard Salinas, United Airlines

Rapporteur: Mr. Donald Carver, Federal Aviation Administration (FAA) 

This session featured six oral and two poster presentations focused on aircraft encounters 

with volcanic ash and the impacts of volcanic ash on airline operations. Aircraft 

encounters with Montserrat, Mt. Hekla, Rabaul, and Miyakejima were described, as well 

as how the volcanic ash hazard impacts the operations of airlines such as United Airlines 

and Air Niugini. The fact that ash can reach commercial flight levels within minutes and 

that even apparent diffuse ash can cause significant engine damage highlighted the need 

for early detection and warning. 

Session 2: The Volcanic Ash Source - Eruption Monitoring and Reporting 

Session Chairs: Ms. Marianne Guffanti, United States Geological Survey (USGS)

 Dr. Steven McNutt, Geophysical Institute, University of Alaska 

 and the International Association of Volcanology and Chemistry of 

 the Earth’s Interior 

Rapporteur: Ms. Terry Keith, USGS 

This session featured eight oral and 13 poster presentations focused on eruption 

monitoring and reporting. The first oral presentation provided a global perspective on 

volcanoes and their eruptions and noted that many of the world’s active volcanoes are in 

developing countries and that monitoring these volcanoes is difficult. Several of the 

presentations noted the difficulty in monitoring volcanoes and in determining the timing 

and strength of potential eruptions. There were also presentations on current capabilities 

for monitoring volcanic eruptions in the North Pacific and in the Western Pacific. Other 

initiatives such as a prototype infrasound system; an alert-level notification scheme for 

aviation, using volcanic tremors in estimating eruption parameters; and ground-based 

detection of ash and sulphur dioxide were presented as well. Points emerging from this 

session included the need for instrumenting more volcanoes that pose a threat to aviation, 

the need for more research on volcanic processes and ash cloud characterization, and the 

need for a standardized warning system. 
3-2

Session 3: Ash Cloud Observations, Modeling, and Forecasting 

Session Chairs: Dr. William Rose, Michigan Technological University (MTU)

 Ms. Barbara Stunder, NOAA Air Resources Laboratory

 Mr. Andrew Tupper, Bureau of Meteorology, Volcanic Ash 

 Advisory Centre, Darwin, Australia 

Rapporteur: Ms. Alexandria Matiella, MTU 

This session featured eight oral and 22 poster presentations focusing on ash cloud 

observations and forecasting ash cloud movements, using volcanic ash transport and 

dispersion models. Several different transport and dispersion models including 

VAFTAD, CANERM, HYSPLIT, and PUFF were presented. Various techniques for 

detecting volcanic ash clouds, using satellite and radar, were also presented. It was also 

noted that use of various satellite techniques provide valuable information on the wet and 

dry processes that remove ash particles. Speakers agreed that difficulties in knowing the 

ash plume parameters and the meteorology often cause uncertainties in the models. 

Session 4: Volcanic Ash Advisory Center (VAAC) Operations and Capabilities 

Session Chairs: Ms. Grace Swanson, NOAA National Environmental Satellite, 

 Data, and Information Service, Volcanic Ash Advisory Center, 

 Washington, D.C. 

 Mr. Rene Servranckx, Environment Canada, Canadian 

 Meteorological Center, Volcanic Ash Advisory Centre, Montreal, 

 Canada 

Rapporteur: Mr. Donald Carver, FAA 

This session featured ten oral and seven poster presentations focusing on various aspects 

of VAAC operations. Two papers highlighted the roles of the ICAO and the World 

Meteorological Organization (WMO) in dealing with the volcanic ash threat. Several 

papers provided operational capabilities at several VAACs, including the Washington 

VAAC, the Tokyo VAAC, the Montreal VAAC, the London VAAC, and the Darwin 

VAAC. The importance of shared situational awareness and collaboration were stressed 

in several papers, and the capabilities of a new pilot program called the Volcanic Ash 

Collaboration Tool were highlighted as a possible way to enhance collaboration among 

international agencies. 
3-3

Session 5: Aviation Industry Perspectives 

Session Chairs: Mr. Steven Albersheim, FAA

 Mr. John Murray, National Aeronautics and Space 

 Administration/Langley Research Center 

Rapporteur: Mr. Floyd Hauth, Science and Technology Corporation

This session featured seven oral and one poster presentations focusing on the volcanic 

ash threat from the perspective of the aviation industry. Highlighted areas dealt with the 

transfer of R&D to operations, how volcanic ash impacts airport operations, and the 

impact of volcanic ash on air traffic control. The importance of the timely dissemination 

of volcanic ash information was stressed and a conceptual framework for streamlining the 

flow of information was provided. 

Plenary Sessions Summary 

Two themes that emerged from the plenary sessions were better communications and 

more education/training. Specific actions included: 

o Improve communications to move data and information between all entities. 

o Increase post-encounter investigations for development of better procedures and 

services. 

o Provide airline pilots with more training with emphasis on hazard awareness. 

o Increase the number of potentially hazardous volcanoes that are monitored by 

ground geophysical instruments. 

o Perform more research on ash cloud characteristics to better define the hazard for 

dispersion models. 

o Perform more research on fundamental volcanic processes that lead to 

“eruptions” versus “failed eruptions.” This will help provide improved forecasts 

on the type, size, and duration of the eruption column as well as the end of the 

eruption. 

o Obtain adequate funding to ensure that all potentially active volcanoes in the 

U.S. are instrumented and monitored. 

o Standardize formats in alert messages. 

o Optimize current satellite sensors for ash detection (atmospheric corrections, 

e.g., SO2). 

o Provide users more information in the pilot report (PIREP), in addition to a 

broader transmission of all reports in real time. 

 
3-4
4-1

BREAKOUT SESSIONS 

The associated breakout sessions provided an opportunity for continued discussion of 

issues raised by presenters in the five plenary sessions. 

Breakout Session 1: Improving Volcanic Ash Cloud Detection 

Session Moderators: Dr. David Schneider, U.S. Geological Survey (USGS), 

 Alaska Volcano Observatory 

 Dr. Steven Ackerman, Cooperative Institute for 

 Meteorological and Satellite Services, University of 

 Wisconsin - Madison 

Rapporteur: Ms. Emily McCarthy, Michigan Technological University 

 (MTU) 

This breakout session was associated with Plenary Session 3 (Ash Cloud Observations, 

Modeling, and Forecasting). Some of the issues discussed dealt with enhanced satellite 

imagery for ash detection, satellite-based assessments of ash density and height, and ash 

detection using remote sensing by radar and reconnaissance flights. 

Breakout Session 2: Improving Modeling Capabilities 

Session Moderators: Mr. Rene Servranckx, Environment Canada, Canadian 

 Meteorological Center, Volcanic Ash Advisory 

Center, Montreal

 Ms. Barbara Stunder, National Oceanic and Atmospheric 

 Administration/Office of Oceanic and Atmospheric 

 Research/Air Resources Laboratory (NOAA/OAR/ARL)

Rapporteur: Ms. Alexandra Matiella, MTU

This breakout session was associated with Plenary Session 3 (Ash Cloud Observations, 

Modeling, and Forecasting). Some of the issues discussed dealt with defining the ash 

cloud edge, identifying source-term improvements, assimilating ash cloud observations 

into dispersion models, and educating the user of model output for better interpretation 

and decision making. It was recommended that a database be established for use by 

researchers, modelers, volcanologists, etc. The database would include information on 

eruptions, ash clouds, satellite imagery, and model output and would serve as a central 

location of information. 
4-2

Breakout Session 3: Understanding the Socioeconomic Consequences 

Session Moderators: Mr. Floyd Hauth, Science and Technology Corporation 

 (STC) 

 Mr. Peter Lechner, Civil Aviation Authority of New Zealand 

Rapporteur: Mr. Floyd Hauth, STC

This breakout session was associated with Plenary Session 1 (Encounters, Damage, and 

Socioeconomic Consequences). Some of the issues discussed dealt with the costs to en 

route operations associated with the ash hazard; identifying the impact on aerodrome 

operations; identifying the cost benefits associated with improved detection, reporting, 

and forecasting; and identifying criteria for prioritizing research. Recommendations 

included identifying costs associated with ash encounters and the benefits from 

mitigation efforts; establishing a process for closing an airport because of volcanic ash; 

and establishing a policy on the required spatial separation for ash avoidance. It was also 

recommended that all volcanic ash incidents, level 3 and above, be reported. 

Breakout Session 4: Improving Volcanic Eruption Reporting 

Session Moderators: Ms. Christina Neal, U.S. Department of the 

 Interior/USGS/Alaska Volcano Observatory 

 Ms. Cynthia Gardner, U.S. Department of the 

 Interior/USGS/Cascades Volcano Observatory 

Rapporteur: Ms. Gari Mayberry, USGS 

This breakout session was associated with Plenary Session 2 (The Volcanic SourceEruption Monitoring and Reporting). Some of the issues discussed dealt with identifying 

new methods of volcano monitoring in support of aviation users, characterizing the type 

of volcano activity report that is optimal for aviation users, and identifying where volcano 

reporting can be improved. The group agreed that the characteristics of a good volcanic 

activity report included being timely, consistent, and simple. Other considerations for 

aviation users included plume height, use of feet, miles, and decimal degrees as the 

preferred units, and the notification of increasing volcano activity. 
4-3

Breakout Session 5: Technology Transfer from Research into Operations 

Session Moderators: Mr. Mark Andrews, Department of 

 Commerce/NOAA/National Weather Service/Aviation 

 Weather Services

 Ms. Debi Bacon, U.S. Department of 

Transportation/Federal Aviation Administration 

Rapporteur: Mr. Thomas Fraim, Office of the Federal Coordinator for 

 Meteorological Services and Supporting Research 

This breakout session was associated with Plenary Session 5 (Aviation Industry 

Perspectives). Some of the issues discussed dealt with current technology transfer 

procedures and possible improvements to these procedures, the private-sector perspective 

implementing new technologies, and understanding how technology is introduced in 

support of international air navigation. The discussion focused on the FAA’s Aviation 

Weather Technology Transfer (AWTT) process which covers end-user products. 

Systems such as the Integrated Terminal Weather System (ITWS) do not come under the 

AWTT process. It was noted that one product (Volcanic Ash Graphic) is currently in the 

AWTT pipeline. It was recommended that the AWTT process be expanded to include 

agencies involved in more basic research in order to better link basic research with 

operational applications. 

Breakout Session 6: Improving VAAC Operational Capabilities 

Session Moderators: Mr. Raul Romero, International Civil Aviation 

 Organization, Montreal, Canada 

 Ms. Grace Swanson, U.S. Department of 

 Commerce/NOAA/National Environmental Satellite, Data, 

 and Information Service (NESDIS)/Volcanic Ash Advisory 

 Center, Washington, D.C., USA

Rapporteur: Ms. Donna McNamara, NOAA/NESDIS 

This breakout session was associated with Plenary Session 4 (VAAC Operations and 

Capabilities). Some of the issues discussed dealt with reducing inconsistencies among 

VAACs and Meteorological Watch Offices (MWOs) in interpreting the significance of 

ash events, achieving necessary staffing levels and training, reducing communications 

problems, and leveraging opportunities for improved cooperation and sharing of 

information. Two issues from this session concerned the dissemination of Volcanic Ash 

Advisories and training. Graphical products are preferred, but format standardization and 

communications present challenges. Training is a continuing issue. It was noted that 

ICAO only sets training requirements; the actual training is the responsibility of 

individual states. The biggest operational challenges are eruption notification, 

determining plume height, model inaccuracies, and communications. 
4-4

Breakout Session 7: Meeting Aviation Needs 

Session Moderators: Mr. William Phaneuf, Air Line Pilots Association

 Mr. Richard Heuwinkel, FAA

Rapporteur: Mr. Donald Carver, FAA

This breakout session was associated with Plenary Session 5 (Aviation Industry 

Perspectives). Some of the issues discussed dealt with requirements for the 

dissemination and display of volcanic ash information, evaluating current and proposed 

products, the ash threshold for closing airspace and the criteria for resuming operations, 

and the timeliness of reports and ash information. Emerging themes from this session 

included the standardization of products from VAAC to VAAC, the need for graphical 

products, communication links to get the information to the cockpit, and training. 

Breakout Sessions Summary 

The breakout sessions continued to have similar issues and action items which were first 

mentioned in the plenary sessions. These are: 

○ Clearly define the 5-minute warning issue as a requirement or a goal. 

○ Define a detection threshold concentration for volcanic ash cloud. 

○ Establish a database on volcanic eruption for use by all interested parties. This 

database would include, for example, information on ash clouds, satellite data, and model 

output. 

○ Establish a web page for volcanologic community to contain at a minimum 1) sample 

interagency plans and notification strategies; 2) recommended standard reporting format 

for volcanic warnings from volcanologists; 3) tutorial for volcanologists on the aviation 

and aviation-meteorology terms and procedures (e.g., SIGMETs); and 4) information on 

how to obtain ICAO Annex 3 and the ICAO Manual on Volcanic Clouds. 

○ Explore the issue of uncertainty in modeling results. Would a measure of uncertainty 

be useful to the user community? 

○ Provide education/training on models and on the interpretation of model results. As a 

first step, model guidance could be posted on VAAC web sites for education and decision 

making. 

○ Establish a process to identify and collect cost/benefit data. 

○ Establish/coordinate a policy on spatial avoidance of known volcanic ash clouds. 

○ ICAO should initiate/coordinate a requirement to report all volcanic ash incidents on 

Level 3 and above (severity scale index). 

○ Improve the FAAs technology transfer process to include more participation from 

users, particularly those agencies involved in basic research (e.g., NASA), to provide a 

user’s utility feedback loop. 

○ Improve the requirements for advanced sensors for ash and eruption detection on 

future geostationary satellites. 
4-5

○ Improve and provide more graphical depiction of volcanic ash products and forecasts 

to pilots/dispatchers for situational awareness and route planning. 

○ Standardize products between VAACs. 
5-1

REGIONAL BREAKOUT SESSIONS 

The regional breakout sessions were intended to provide a forum to discuss issues 

pertinent to particular regions. By bringing together operators, researchers, and scientists 

who work in a given region, operational improvements can be identified for issues, 

ranging from eruption reporting to model output to VAAC protocols. Many user needs 

were brought out, including the need for continuing efforts directed at improving the 

timely detection and forecasting of ash dispersion and the need to reduce inconsistencies 

across adjacent areas of responsibility when different dispersion models are used. 

Breakout Session 8: North Asia Pacific (e.g., Alaska, Russia, Japan) 

Session Moderators: Mr. Christopher Strager, U.S. Department of Commerce/National 

 Oceanic and Atmospheric Administration 

 Ms. Terry Keith, U.S. Department of the Interior/U.S. Geological 

 Survey/Alaska Volcano Observatory 

Breakout Session 9: The Americas and the Caribbean (excluding Alaska) 

Session Moderators: Dr. Patricia Mothes, Instituto Geofísico de la Escuela Politécnica 

 Nacional, Ecuador

 Mr. J. Armando Saballos, Instituto Geofísico de la Escuela 

 Politécnica Nacional, Ecuador 

 Richard Hernandez, Federal Aviation Administration 

Breakout Session 10: Europe, Africa, and the Middle East 

Session Moderators: Dr. Gerald Ernst, Department of Geology and Soil Science, 

 University of Ghent, Belgium 

 Mr. Jean-Philippe Desbios, Volcanic Ash Advisory Center, 

 Toulouse, France 

Breakout Session 11: South Asia Pacific (e.g., Indonesia, the Philippines, Australia, 

and New Zealand) 

Session Moderators: Mr. Rodney Potts, Australian Bureau of Meteorology Research 

 Centre

 Captain David Innes, Air Niugini 

The regional breakout sessions had one underlying issue they would like to see 

addressed: 

○ Conduct regional workshops to provide training on volcanic ash and to improve the 

implementation of the International Airways Volcanic Watch. In particular, there is a 

need to refine communication protocols through table-top exercises, multiagency 

operational plans, etc. 
5-2
6-1

CLOSING SESSION 

ICAO’s Commitment to Mitigating the Volcanic Ash Hazard 

On Thursday morning, Mr. William Voss, Director, Air Navigation Bureau, ICAO, was 

represented by Mr. Raul Romero, Technical Officer, Meteorology Section, International 

Civil Aviation Organization. Mr. Romero addressed the background of the ICAO and 

WMO involvement in volcanic ash, with respect to airline regulations and the formation 

of the Volcanic Ash Advisory Centers and the International Airways Volcano Watch. He 

stressed the importance for the volcanic ash community to continue to work together, 

especially in the areas of communications, training, and education. 

Conference Highlights 

The overall goal of providing a forum for exchanging scientific and operational 

information for the purpose of identifying ways to improve the mitigation of the volcanic 

ash hazard to aviation was met. With over 20 countries represented, this conference 

provided an unparalleled opportunity for the attendees to network and strengthen the 

partnerships in mitigating the volcanic ash hazard. The key stakeholders represented 

included government and academic scientists, operational meteorologists, product 

developers, aviation regulators, pilots, dispatchers, and international organizations 

dealing in aviation and meteorological matters. The operational components of the 

International Airways Volcano Watch team were represented, including all the VAACs, 

the volcano observatory community, and many of the Meteorological Watch Offices 

(MWO). With a goal of reducing volcanic ash encounters to zero, two basic actions 

emerged from the conference: sustained vigilance and regional workshops. Sustained 

vigilance in order to avoid complacency, and additional regional workshops in order to 

improve implementation of the International Airways Volcano Watch. 

Building on Our Successes in Aviation Safety for the Next Decade 

Identify new operational needs/requirements and the research and development needed to 

satisfy those requirements. These included: 

• Need for additional information in PIREPs for use in defining existence or 

dissipation of volcanic ash. 

• Definition of the airlines’ need for 5-minute notification of volcanic eruption. 

• Optimizing current satellite sensors for ash detection, including ensuring 

volcanic ash community is directly involved with satellite detection research 

projects (e.g., SO2 detection). 

• Need for more access to airlines reporting engine problems from volcanic ash 

encounters after-the-fact to be able to study the effects of damage. 

• Provide satellite requirements for volcanic eruptions and ash plumes to the 

Group on Earth Observations (GEO) Architecture Subgroup for critical 

elements for the Global Earth Observing System. 
6-2

Where possible, match operational and research and development needs/requirements to 

ongoing programs/projects to maximize partnership effort. 

• NASA will continue to leverage resources in their aviation weather research, 

especially the areas for hazard mitigation research associated with the Advanced 

Satellite Aviation-Weather Products project. 

• FAA’s Aviation Weather Research Program provides opportunities for 

collaboration on mitigation of volcanic ash in the Oceanic Weather Product 

Development Team. 

Develop a roadmap for improved volcanic ash-related education, training, outreach, and 

decision tools. 

• Conduct regional workshops to provide training on the volcanic ash and aviation 

safety issue and improve implementation of the International Airways Volcano 

Watch. Especially, refine communications protocols through table-top 

exercises, multiagency operational plans, etc. 

• Recommend ICAO provide a website for an international source of training 

materials. 

• Conduct training for both sources and users (volcanologists/meteorologists & 

Automated Flight Service Station personnel/airline dispatchers/aircrews). 

• Develop a final four-dimensional graphic of the volcanic ash situation and 

expected changes for both airline pilots and dispatchers. 

Develop a framework for improved partnerships within the international volcanic ash 

community to leverage resources and capabilities across the spectrum of operations and 

research and development. 

• Identify additional sources of funding within WMO, ICAO, and U.S. agencies 

for improvements to communications (e.g., between MWO and VAACs) and 

training. 

• Form an aviation issues group within IAVCEI for addressing volcanic ash 

mitigation for airline safety. In addition, work with the IAVCEI Commission 

on Education to provide training to vulcanologists on the effects on aviation 

safety. 

• Create a new list serve on the internet focused on ash mitigation issues, 

particularly those covered during the conference. 
6-3

Next Steps 

The OFCM Working Group for Volcanic Ash (WG/VA) will take action on the 

conference action items and recommendations including: (1) seek help, input, and advice 

from international partners and the International Civil Aviation Organization, (2) sort 

action items and recommendations into short- (0-12 month), mid- (1-4 year), and longterm (4-10 year) actions and prioritize them, and (3) develop and gain approval of a 

Volcanic Ash Implementation Plan, outlining program goals, operational 

needs/requirements, and R&D needs and priorities, within the next 12 months. OFCM 

will publish a proceedings volume from the conference by early fall. 
6-4
 A-1

APPENDIX A 

AGENDA 
 A-2
 A-3

AGENDA 

 

Sunday 20 June 2004 

5:00 PM Early Registration (5:00-8:00) 

Monday 21 June 2004

7:00 AM Registration open 

 Continental Breakfast 

Opening Session

8:30 AM Conference Welcome and Introduction of the Mayor of Alexandria, VA 

• Mr. Samuel P. Williamson, Federal Coordinator for Meteorological Services and 

Supporting Research 

8:35 AM Welcome 

• Mayor William “Bill” Euille, Alexandria, VA 

8:45 AM Conference Objectives and Introductions 

• Mr. Samuel P. Williamson, Federal Coordinator for Meteorological Services and 

Supporting Research 

9:00 AM Keynote Address/Invited Speakers 

• The Honorable Ted Stevens, United States Senate (invited) 

• Dr. James R. Mahoney, Assistant Secretary of Commerce for Oceans and Atmosphere 

and NOAA Deputy Administrator 

• Dr. Charles G. Groat, Director, U.S. Geological Survey 

• RADM. James P. Schear, Vice President for Safety, Federal Aviation Administration 

10:30 AM Morning Coffee Break (10:30 – 11:00) 

• Mr. Ronald J. Birk, Director of the Earth Science Applications Division, Office of Earth 

Science, NASA 

• Mr. Gianni Semenzato, Senior Flight Inspector, Ente Nazional per L’Aviazione Civile 

(Italian Civil Aviation Authority) 
 A-4

12:00 PM Luncheon (Sponsored by Air Line Pilots Association) 

• Guest Speaker: Captain Eric Moody, British Airways (Ret.), Gliding a B747 Out of 

Volcanic Ash.

1:30 PM Panel 1 – Airborne Volcanic Ash: Perspectives, Challenges, and Opportunities 

Panel Moderator: Dr. Elbert W. (Joe) Friday, WeatherNews Professor of Meteorology and 

Founding Director of the Sasaki Applied Meteorology Research Institute, 

University of Oklahoma 

Panelists: 

• Dr. Thomas P. Miller, Scientist Emeritus, USGS Alaska Volcano Observatory 

• Dr. Louis W. Uccellini, Director, NOAA’s NWS National Centers for Environmental 

Prediction 

• Ms. Gloria Kulesa, Manager, Aviation Weather Research, FAA 

• Mr. Alan Shaffer, Director, Plans and Programs, Office of the Secretary of Defense 

• Mr. Peter Chen, Director, Operations Branch, Canadian Meteorological Center, 

Environment Canada 

3:00 PM Afternoon coffee break (3:00-3:30) 

3:30 PM Panel 2: Education, Training, and Outreach 

Panel Moderator: Dr. Gregory S. Forbes, Severe Weather Expert, The Weather Channel 

Panelists: 

• Ms. Cyndie Abelman, Meteorologist-In-Charge, National Oceanic and Atmospheric 

Administration/National Weather Service, Oklahoma City, OK 

• Captain Albert M. Beerley, US Airways Airbus, US Airways/ALPA Training Committee 

• Mr. John O’Brien, Director, Engineering and Air Safety Department, Air Line Pilots 

Association 

• Mr. Saburo Onodera, Manager, Flight Crew Training Department, Japan Airlines 

• Professor Eric Doten, Director of Center for Aerospace Safety/Security Education, 

Embry-Riddle Aeronautical University 

5:00 PM Administrative Remarks 

 Erin McNamara, Conference Coordinator for Logistics 

 Exhibits open 

 Posters displayed 

 OFCM Staff Meeting 

5:30 PM Icebreaker (Sponsored by Tenix Corporation) 
 A-5

Tuesday 22 June 2004

7:00 AM Continental Breakfast

7:55 AM Administrative Remarks 

 Erin McNamara, Conference Coordinator for Logistics 

Plenary Sessions 

8:00 AM Session 1: Encounters, Damage, and Socioeconomic Consequences 

Session Chairs: Mr. Edward Miller, Air Line Pilots Association (ALPA) 

Mr. Leonard Salinas, United Airlines (UAL) 

8:00 AM 1.1 2003 Caribbean Volcanic Ash Encounters 

Captain Albert M. Beerley, US Airways ALPA Training Committee, 

Philadelphia, PA, USA 

8:20 AM 1.2 Engine Damage to a NASA DC-8-72 Airplane from a High-Altitude 

Encounter with a Diffuse Volcanic Ash Cloud 

Thomas J. Grindle, NASA, Edwards, CA, USA; and Frank W. Burcham, Jr. 

8:40 AM 1.3 Aircraft Encounters from the 18th August 2000 Eruption at Miyakejima, 

Japan 

Andrew Tupper, Bureau of Meteorology, Darwin, Australia; and Yasuhiro 

Kamada, Noriyuki Todo, Ed Miller 

9:00 AM 1.4 Impacts of Volcanic Ash on Airline Operations 

Leonard J. Salinas, United Airlines Flight Dispatch, Chicago, Illinois, USA; 

and Daniel Watt 

9:20 AM 1.5 Air Niugini and the Volcanic Ash Threat 

Captain David Innes, Flight Safety Office, Air Nuigini, Papua, New Guinea 

9:35 AM 1.6 Reducing Encounters of Aircraft with Volcanic Ash Clouds 

Marianne Guffanti, USGS, Reston, VA, USA; and Thomas J. Casadevall, 

Gari Mayberry 

9:45 AM Poster Preview by Session Chair 

 Exhibits open (8:00-5:00) 

 Posters displayed 

10:00 AM Morning coffee break (10:00-10:30) 

 Exhibits staffed (10:00-3:30) 

10:30 AM Session 2: The Volcanic Source - Eruption Monitoring and Reporting 

Session Chairs: Ms. Marianne Guffanti, U.S. Department of the Interior/U. S. 

Geological Survey (DOI/USGS) 

 Dr. Steven McNutt, Geophysical Institute, University of 

Alaska and the International Association of Volcanology 

and Chemistry of the Earth’s Interior (IAVCEI) 
 A-6

10:30 AM 2.1 A Global Perspective on Volcanoes and Eruptions 

Richard Wunderman, Smithsonian Institution, Washington, DC, USA; and 

Lee Siebert, James Luhr, Tom Simkin, Ed Venzke 

10:45 AM 2.2 Promise and Pitfalls in Eruption Forecasting 

Chris Newhall, USGS, Seattle, WA, USA 

11:00 AM 2.3 Status of Volcano Monitoring Worldwide 

John W. Ewert, USGS, VDAP, Vancouver, WA, USA; and Christopher G. 

Newhall 

11:10 AM 2.4 Volcanic Alert Systems: An Overview of their Form and Function 

Bradley Scott, Institute of Geological and Nuclear Sciences, Wairakei, New 

Zealand 

11:25 AM 2.5 Recent Etna’s Explosive Eruptions Threaten Seriously Aviation in Central 

Mediterranean Region 

Mauro Coltelli, INGV, Catania, Italy 

11:40 AM 2.6 Recent Eruptive Activity in Ecuadorian Volcanoes and its Threat to Aviation 

Safety 

Hugo Yepes A., Instituto Geofisico, Escuela Politecnica Nacional, QuitoECUADOR 

11:55 AM 2.7 The Alaska Volcano Observatory – Fifteen Years of Working to Mitigate the 

Risk to Aviation from Volcanic Ash in the North Pacific 

Thomas L. Murray, USGS, AVO, Anchorage, AK, USA 

12:05 PM 2.8 Ground-Based Real Time Monitoring of Eruption Clouds in the Western 

Pacific 

Kisei Kinoshita, Kagoshima University, Kagoshima, Japan; and Satoshi 

Tsuchida, Chikara Kanagaki, Andrew C. Tupper, Ernesto G. Corpuz, 

Eduardo P. Laguerta 

12:20 PM Poster Preview by Session Chair 

12:30 PM Lunch (12:30-1:30; catered) 

1:30 PM Session 3: Ash Cloud Observations, Modeling, and Forecasting 

Session Chairs: Dr. William Rose, Michigan Technological University (MTU) 

Ms. Barbara Stunder, U.S. Department of Commerce/National 

Oceanic and Atmospheric Administration/Office of Oceanic 

and Atmospheric Research/Air Resources Laboratory 

(DOC/NOAA/OAR/ARL) 

Mr. Andrew Tupper, Bureau of Meteorology, Volcanic Ash 

Advisory Center (VAAC), Australia 

1:30 PM 3.1 Modeling Volcanic Ash Transport and Dispersion: Expectations and Reality 

Rene Servranckx, CMC, MSC, Quebec, Canada; and Peter Chen 

1:46 PM 3.2 Discrepancies Between Satellite Detection and Forecast Model Results of Ash 

Cloud Transport: Case Study of the 2001 Eruption of Mt. Cleveland Volcano, 

Alaska 

David J. Schneider, USGS, AVO, Anchorage, AK, USA; Rene Servranckx, 

Jeff Osiensky 
 A-7

2:00 PM 3.3 Assessing Volcanic Ash Hazard by Using the CALPUFF System 

Sara Barsotti, Istituto Nazionale di Geofisica e Volcanologia, Pisa, Italy; and 

Augusto Neri, Joe Scire 

2:12 PM 3.4 Potential of the ATHAM Model for Use in Air Traffic Safety 

Christiane Textor, Lab. Sciences du Climate et de L’Environnement, Paris, 

France; and Gerald Ernst 

2:24 PM 3.5 Volcanic Ash and Aerosol Detection Versus Dust Detection Using GOES and 

MODIS Imagery 

Bernadette Connell, CIRA/CSU, Fort Collins, CO, USA 

2:36 PM 3.6 Ice in Volcanic Clouds: Where and When? 

William I. Rose, Michigan Technological University, Houghton, MI, USA 

2:48 PM 3.7 Detection of Upper Level SO2 via the GOES Sounder 

Fred Prata, CSIRO Atmospheric Research, Aspendale, Australia; and 

Anthony J. Schreiner, Gary P. Ellrod, Timothy J. Schmit 

3:00 PM 3.8 The G-bIRD Volcanic Ash Cloud Detection System 

Bill Young, Tenix, Sydney, Australia; and Matthew Simmons 

3:12 PM Poster Preview by Session Chair 

3:15 PM Afternoon coffee break (3:15-3:45)

3:45 PM Session 4: VAAC Operations and Capabilities 

Session Chairs: Ms. Grace Swanson, U.S. Department of Commerce/National 

Oceanic and Atmospheric Administration/National 

Environmental Satellite, Data, and Information 

Service/Volcanic Ash Advisory Center, Washington, D.C., 

USA (DOC/NOAA/NESDIS/VAAC) 

Mr. Rene Servranckx, Environment Canada, Canadian 

Meteorological Center, Volcanic Ash Advisory Center, 

Montreal (EC/CMC/VAAC) 

3:45 PM 4.1 The International Airways Volcano Watch (IAVW) 

Raul Romero, ICAO, Montreal, Canada 

3:55 PM 4.2 WMO Activities Related to Volcanic Ash 

Saad Benarafa, World Meteorological Organization, Geneva, Switzerland 

4:00 PM 4.3 NOAA’s NWS Volcanic Ash Program: Current Status and Plans for the 

Future 

Christopher S. Strager, NWS Alaska Region Headquarters, Anchorage, AK, 

USA; and Jeffrey M. Osiensky, Gary L. Hufford 

4:10 PM 4.4 Volcanic Ash Impact on International Airport of Mexico City (AICM), Due 

to Emissions of Popocatepetl Volcano 

Humberto Rodriguez, DMTA of SENEAM, Mexico, D.F. Mexico 

4:20 PM 4.5 The Darwin VAAC Volcanic Ash Workstation 

Rodney Potts, Bureau of Meteorology Research Centre, Melbourne, 

Australia; and Mey Manickam, Andrew Tupper, Jason Davey 
 A-8

4:30 PM 4.6 Shared Situational Awareness and Collaboration Through the Use of the 

Volcanic Ash Collaboration Tool (VACT) 

Jeffrey M. Osiensky, NWS Alaska Aviation Weather Unit, Anchorage, AK, 

USA; and Greg Pratt, David J. Schneider, Lynn Sherretz 

4:40 PM 4.7 Perspectives on Operational Volcanic Ash Warnings 

Hordur Thordarson, Meteorological Service of New Zealand, Wellington, 

New Zealand 

4:50 PM 4.8 Volcanic Cloud Conceptual Models for Volcanic Ash Advisory Centre 

Operations 

Andrew Tupper, Bureau of Meteorology, Darwin, Australia; and Gerald 

Ernst, Christiane Textor, Kisei Kinoshita, J. Scott Oswalt, Daniel Rosenfeld 

5:00 PM 4.9 Volcanic Ash Advisory Support for the U.S. Department of Defense 

Charles Holliday, U.S. AFWA, Offutt AFB, Nebraska, USA 

5:05 PM 4.10 Web Access to the Digital Archive of VAA Messages and VAFTAD Model 

Output 

Paula Dunbar, NOAA/NESDIS/NGDC, Boulder, CO, USA; and Grace 

Swanson 

5:10 PM Poster Preview by Session Chair 

5:30 PM Sessions end for the day 

 OFCM Staff Meeting

7:00 PM Tour Washington VAAC 

 
 A-9

Wednesday 23 June 2004

 

7:00 AM Continental Breakfast

7:55 AM Administrative Remarks 

 Erin McNamara, Conference Coordinator for Logistics

8:00 AM Session 5: Aviation Industry Perspectives 

Session Chairs: Mr. Steven R. Albersheim, U.S. Department of 

Transportation/Federal Aviation Administration (DOT/FAA) 

Mr. John Murray, National Aeronautics and Space 

Administration/Langley Research Center (NASA/LaRC) 

8:00 AM 5.1 Technology Transfer: Moving R&D to Operations 

Steven R. Albersheim, Federal Aviation Administration, Washington, D.C., 

USA 

8:15 AM 5.2 The Effect of Volcanic Activity on Airports 

Marianne Guffanti, USGS, Reston, VA, USA; and Gari Mayberry, Rick 

Wunderman, Thomas J. Casadevall 

8:30 AM 5.3 An Air Traffic Controller Perspective on Volcanic Ash: How to Deal with It! 

Richard Hernandez, FAA San Juan Automated International Flight Service 

Station, San Juan, Puerto Rico, USA 

8:50 AM 5.4 The New Zealand Volcanic Ash Advisory System 

Peter Lechner, Civil Aviation Authority of New Zealand, Wellington, NZ 

9:05 AM 5.5 Prevention of Volcanic Ash Encounters in the Proximity Area Between 

Active Volcanoes and Heavy Air Traffic Routes 

Saburo Onodera, Flight Crew Training Department, Japan Airlines, Tokyo, 

Japan 

9:20 AM 5.6 A Program for Research and Systems Integration to Help Mitigate the 

Volcanic Ash Hazard to Aviation 

Tenny A. Lindholm, National Center for Atmospheric Research (NCAR), 

Boulder, CO, USA 

9:35 AM 5.7 Explosive Volcanic Eruptions Across the Heavily Traveled North Pacific Air 

Routes: Frequency, Duration, and Impact on Aviation 

Thomas P. Miller, USGS, AVO, Anchorage, AK, USA 

9:55 AM Poster Preview by Session Chair 

 Exhibits open (8:00-5:00) 

 Posters displayed 

10:00 AM Morning coffee break (10:00-10:30) 

 Exhibits staffed (10:00-3:30) 

10:30 AM Breakout Sessions (10:30-12:30) 
 A-10

Breakout Session 1: Improving Volcanic Ash Cloud Detection

Session Moderators: Dr. David J. Schneider, U.S. Geological Survey, Alaska Volcano 

Observatory (USGS/AVO) 

Dr. Steven Ackerman, Cooperative Institute for Meteorological and 

Satellite Services, University of Wisconsin - Madison 

Breakout Session 2: Improving Modeling Capabilities

Session Moderators: Mr. Rene Servranckx, Environment Canada, Canadian Meteorological 

Center, Volcanic Ash Advisory Center, Montreal (EC/CMC/VAAC) 

Ms. Barbara Stunder, U.S. Department of Commerce/National Oceanic 

and Atmospheric Administration/Office of Oceanic and Atmospheric 

Research/Air Resources Laboratory (DOC/NOAA/OAR/ARL) 

Breakout Session 3: Understanding the Socioeconomic Consequences

Session Moderators: Mr. Floyd Hauth, Science and Technology Corporation 

 Mr. Peter Lechner, Civil Aviation Authority of New Zealand 

12:30 PM Lunch (12:30-1:30; catered) 

1:30 PM Poster Session (1:30-3:30) 

P1.1 Three Aircraft Encounters over Micronesia 

Andrew Tupper, Bureau of Meteorology, Darwin, Australia; and Jason Davey, Paul 

Stewart, Barbara Stunder, Rene Servranckx 

P1.2 Sulfurous Odors: A Signal of Entry into an Ash Plume – But Perhaps Less Reliable 

for Escape 

Richard Wunderman, Smithsonian Institution, Washington, DC, USA 

P2.1 Evaluation of a Prototype Infrasound System for Enhancing Volcanic Ash Warnings 

Henry Bass, University of Mississippi; and Milton Garces, David McCormack, Peter 

Chen, Michel Jean 

P2.2 Recurrence of Explosive Eruptions at Etna Volcano that Produce Hazard for Aviation 

Paola Del Carlo, INGV, Catania, Italy 

P2.3 A Proposed Alert-level Notification Scheme for Aviation and Ground-based Hazards 

at U.S. Volcanoes 

C.A. Gardner, USGS, Cascades Volcano Observatory, Vancouver, WA, USA; and 

M.C. Guffanti, C.C. Heliker, D.P. Hill, J.B. Lowenstern, T.L. Murray 

P2.4 Monitoring and Reporting of Kamchatkan Volcanic Eruptions 

Evgenii Gordeev, Institute of Volcanology and Seismology, PetropavlovskKamchatsky, Russia; and Sergei Senjukov, Olga Girina 

P2.5 Volcano-Related Information Available on the Internet: From Current Activity to the 

Past 10,000 Years 

Gari Mayberry, USGS, Washington, DC, USA; and Edward Venzke, James Luhr, 

Richard Wunderman, Lee Siebert, Marianne Guffanti 

P2.6 Volcanic Tremor and its Use in Estimating Eruption Parameters 

Stephen R. McNutt, AVO, Fairbanks, AK, USA 
 A-11

P2.7 Surprise/Sudden Onset Eruptions: The Case of Reventador Volcano – Ecuador, 03-

November, 2002 

Patricia Mothes, Instituto Geofisico, Quito-Ecuador; and Minard L. Hall, Patricia 

Ramon, Hugo Yepes 

P2.8 Ashfall Scenarios and Aviation Impacts of Future Eruptions of Cotopaxi Volcano – 

Ecuador 

Patricia Mothes, Instituto Geofisico, Quito-Ecuador; and Minard L. Hall, Pablo 

Samaniego, Hugo Yepes 

P2.9 Airborne Ash Hazard Mitigation in the North Pacific: A Multi-Agency, International 

Collaboration 

Christina Neal, USGS, Anchorage, AG, USA; and AVO Staff, Olga Girina, Gail 

Ferguson, Jeffrey Osiensky 

P2.10 Ground-Based Detection of Volcanic Ash and Suphur Dioxide 

Fred Prata, CSIRO Atmospheric Research, Aspendale, Australia; and Cirilo 

 Bernardo 

P2.11 The New Zealand Volcano Alert Level System – Its Performance in Recent Eruptive 

Activity 

Bradley Scott, Institute of Geological and Nuclear Sciences, Wairakei, New Zealand 

P2.12 Monitoring of Active Volcanoes of the Kurile Islands: Present and Future 

A.V. Rybin, Institute of Marine Geology and Geophysics, Yuzhno-Sakhalinsk, 

Russia; and Y.V. Karagusov, P.E. Izbekov, N.S. Terentyev, V.B. Guryanov 

P2.13 Volcanic Eruptions as Thunderstorm Ice Factories 

Earle R. Williams, Parsons Laboratory, MIT, Cambridge, MA, USA; and Stephen R. 

McNutt 

P3.1 UW-Madison Advanced Satellite Aviation-weather Products MODIS Satellite 

Volcanic Ash Detection Methodologies 

Steven Ackerman, Wayne F. Feltz, CIMSS/SSEC University of Wisconsin, Madison, 

WI, USA; and Tim Schmit, John Murray, David Johnson 

P3.2 Removal Processes of Volcanic Ash Particles from the Atmosphere 

Gregg Bluth, Michigan Technological University, Houghton, MI, USA; and Bill 

Rose, Matt Watson 

P3.3 Sounding of Volcanic Clouds with Balloon-Borne Instruments: Improving Algorithms 

for Ash and SO2 in Remote Sensing Imagery 

John Chadwick, Idaho State University, Pocatello, ID, USA; and Zach Lifton, Ken 

Dean, Jim Chadwick 

P3.4 FALL3D: A Numerical Model for Volcanic Ash Dispersion in the Atmosphere 

A. Costa, Istituto Nazionale de Geofisica e Vulcanologia, Napoli, Italy; and G. 

Macedonio 

P3.5 Use of Dispersion Models to Track Eruption Clouds 

Ken G. Dean, Geophysical Institute, University of Alaska, Fairbanks, AK, USA; and 

Rorik A. Peterson, Ken Papp, Jonathan Dehn 

P3.6 Laboratory Measurements of Heterogeneous Ice Nucleation by Volcanic Ash: 

Importance for Detecting and Modeling Volcanic Clouds 

Adam J. Durant, Michigan Technological University, Houghton, Michigan, USA; and 

Raymond A. Shaw, Youshi Mi, and William I. Rose 
 A-12

P3.7 Volcanic Ash Detection and Cloud Top Height Estimation from the GOES-12 Imager: 

Coping Without a 12μm Infrared Band 

Gary P. Ellrod, NOAA/NESDIS, Camp Springs, MD, USA; and Anthony J. 

Schreiner, Alonzo M. Brown 

P3.8 Resuspension of Relic Volcanic Ash and Dust from Katmai: Still an Aviation Hazard 

David Hadley, NWS Alaska Aviation Weather Unit, Anchorage, AK, USA; and Gary 

L. Hufford, James J. Simpson 

P3.9 Observing Popocatepetl’s Volcanic Ash Clouds Using MODIS Infrared Data 

M. Alexandra Matiella, Michigan Technological University, Houghton, MI, USA; 

and Hugo Delgado-Granados, William I. Rose, I. Matthew Watson 

P3.10 Comparison of Ash Detection Techniques Using TOMS, MODIS, AVHRR, and GMS: 

A Case Study of the August 18 and 28, 2000 Eruption Clouds of Miyakejima, Japan 

Emily McCarthy, Michigan Technological University, Houghton, MI, USA; and 

Gregg Bluth, Matthew Watson, Andrew Tupper, Yasuhiro Kamada 

P3.11 Predicting Regions Susceptible to High Concentrations of Airborne Volcanic Ash in 

the North Pacific Region 

Kenneth Papp, Geophysical Institute, University of Alaska, Fairbanks, AK, USA; and 

Ken Dean, Jonathan Dehn 

P3.12 Reanalysis of Eruption Clouds from the North Pacific Region and Their Impact on 

Aircraft and Population Centers 

Rorik A. Peterson, Geophysical Institute, University of Alaska, Fairbanks, AK, USA; 

and Ken G. Dean, Ken Papp, Joanne Groves, Jonathan Dehn 

P3.13 Quantitative Sulphur Dioxide Retrievals from AIRS, MODIS and HIRS 

Fred Prata, CSIRO Atmospheric Research, Aspendale, Australia; and Cirilo Bernardo 

P3.14 Sakura – An Airborne Infrared Imaging Camera for the Detection Of Volcanic Ash 

and Sulphur Dioxide Gas 

Fred Prata, CSIRO Atmospheric Research, Aspendale, Australia 

P3.15 Testing Real-Time Remote Sensing for Monitoring Volcanic Activity in Central 

America 

Armando Saballos, INETER, Managua, Nicaragua; and Peter Webley, Martin 

Wooster 

P3.16 Advances in Ultraviolet Detection of Volcanic Eruption Clouds 

Stephen J. Schaefer, Joint Center for Earth Systems Technology UMBC, Baltimore, 

MD, USA; and Arlin J. Krueger, Simon A. Carn 

P3.17 Real-Time Monitoring of the Volcanic Ash Fallout Will Improve Airport Safety 

Simona Scollo, INGV, Catania, Italy; and Mauro Coltelli, Marco Folegani, Stefano 

Natali, Franco Prodi 

P3.18 Operational MODIS Volcanic Ash Products for Aviation Safety and Natural Hazards 

Mitigation 

George Stephens, OSDPD, NOAA/NESDIS, Camp Springs, MD, USA; and Gary P. 

Ellrod, Jun-Sun Im 

P3.19 Volcanic Ash Dispersion Modeling Research at NOAA Air Resources Laboratory 

Barbara Stunder, NOAA/ARL, Silver Spring, MD, USA 

P3.20 Operational Volcanic Ash Plume Prediction Model PUFF at the Japan Airlines 

H.L. Tanaka, Institute of Geoscience, University of Tsukuba and FRSGC, Japan; and 

Saburo Onodera, Daisuke Nohara 
 A-13

P3.21 Correcting Ash Retrievals for the Presence of Atmospheric Water Vapor Using 

Foreward Modeling 

I.M. Watson, Michigan Technological University, Houghton, MI, USA; and W.I. 

Rose, G.J.S. Bluth 

P3.22 Eruption Cloud Echo Measured with C-band Weather Radar 

Yoshihiro Sawada, Hokkaido University, Sapporo, Japan 

P4.1 Operations of Washington Volcanic Ash Advisory Center (VAAC) 

Gregory M. Gallina, NOAA SSD, Camp Springs, MD, USA; and Davida Streett 

P4.2 Improvement of Ash Cloud Information by Tokyo VAAC 

Takeshi Koizumi, Japan Meteorological Agency, Tokyo, Japan; and Yoshihiko 

Hasegawa, Yasuhiro Kamada, Masamichi Nakamura 

P4.3 The Montreal VAAC Toolbox: When Every Second Counts 

Mark McCrady, CMC, MSC, Quebec, Canada; and Serge Trudel, Jean-Philippe 

Gauthier, Rene Servranckx 

P4.4 Eruption of Anatahan Volcano: Operations and Observations 

Michael G. Middlebrooke, NOAA/NWS, Barrigada, Guam 

P4.5 The Volcanic Ash Collaboration Tool (VACT) 

Jeffrey M. Osiensky, NWS Alaska Aviation Weather Unit, Anchorage, AK, USA; 

and Greg Pratt, David J. Schneider, Lynn Sherretz 

P4.6 Volcanic Ash Monitoring and Forecasting at the London VAAC 

Sarah Watkin, Met Office, Exeter, Devon, U.K.; and Derrick Ryall, Helen Watkin, 

Helen Champion, Stewart Wortley, Nigel Gait 

P4.7 Web Access to the Digital Archive of VAA Messages and VAFTAD Model Output 

Paula Dunbar, NOAA/NESDIS/NGDC, Boulder, CO, USA; and Grace Swanson

P5.1 First 8 Hours of Volcanic Eruptions: A Northwest Airlines Example & 

Recommendation of Revised Flow of Ash Information for Aviation 

Tom Fahey, Northwest Airlines, Minneapolis/St. Paul, MN, USA 

3:00 PM Afternoon coffee break (3:00-3:30) 

3:30 PM Breakout Sessions (3:30-5:30) 

Breakout Session 4: Improving Volcanic Eruption Reporting

Session Moderators: Ms. Christina Neal, U.S. Department of the Interior/U.S. Geological 

Survey/Alaska Volcano Observatory (DOI/USGS/AVO) 

Ms. Cynthia Gardner, U.S. Department of the Interior/U.S. Geological 

Survey/Cascades Volcano Observatory (DOI/USGS/CVO) 

Breakout Session 5: Technology Transfer from Research into Operations

Session Moderators: Mr. Mark Andrews, Department of Commerce/National Oceanic and 

Atmospheric Administration/National Weather Service/Aviation 

Weather Services (DOC/NOAA/NWS/AWS) 

 Ms. Debi Bacon, U.S. Department of Transportation/Federal Aviation 

Administration (DOT/FAA) 
 A-14

Breakout Session 6: Improving VAAC Operational Capabilities 

Session Moderators: Mr. Raul Romero, International Civil Aviation Organization, 

Montreal, Canada (ICAO) 

Ms. Grace Swanson, U.S. Department of Commerce/National Oceanic 

and Atmospheric Administration/National Environmental Satellite, 

Data, and Information Service/Volcanic Ash Advisory Center, 

Washington, D.C., USA (DOC/NOAA/NESDIS/VAAC)

Breakout Session 7: Meeting Aviation Needs 

Session Moderators: Mr. William Phaneuf, Air Line Pilots Association (ALPA) 

Mr. Richard Heuwinkel, Department of Transportation/Federal 

Aviation Administration 

5:30 PM Sessions end for the day 

 OFCM Staff Meeting

6:30 PM Reception at the Smithsonian National Museum of Natural History (6:30 PM – 

8:00 PM) 
 A-15

Thursday 24 June 2004

7:00 AM Continental Breakfast

8:00 AM Regional Breakout Sessions (8:00-10:00) 

Breakout Session 8: North Asia Pacific (e.g., Alaska, Russia, Japan) 

Session Moderators: Mr. Christopher Strager, U.S. Department of Commerce/National 

Oceanic and Atmospheric Administration (DOC/NOAA) 

Ms. Terry Keith, U.S. Department of the Interior/U.S. Geological 

Survey/Alaska Volcano Observatory (DOI/USGS/AVO) 

Breakout Session 9: The Americas and the Caribbean (excluding Alaska) 

Session Moderators: Dr. Patricia Mothes, Instituto Geofísico de la Escuela Politécnica 

Nacional, Ecuador 

J. Armando Saballos, Instituto Nicaraguense de Estudios Territoriales, 

Nicaragua 

Richard Hernandez, Federal Aviation Administration 

Breakout Session 10: Europe, Africa, and the Middle East 

Session Moderators: Dr. Gerald Ernst, Department of Geology and Soil Science, University 

of Ghent, Belgium 

Mr. Jean-Philippe Desbios, Volcanic Ash Advisory Center (VAAC), 

Toulouse, France 

Breakout Session 11: South Asia Pacific (e.g., Indonesia, the Philippines, Australia, New 

Zealand) 

 Session Moderators: Mr. Rodney Potts, Australian Bureau of Meteorology Research Centre 

 Capt. David Innes, Air Niugini 

 

10:00 AM Morning coffee break (10:00-10:30) 

Closing Session 

10:30 AM ICAO’s Commitment to Mitigating Volcanic Ash Hazard 

Mr. William Voss, Director, Air Navigation Bureau, International Civil Aviation 

Organization 

10:45 AM Conference Highlights

Ms. Marianne Guffanti, DOI/USGS 

Mr. Andrew Tupper, Bureau of Meteorology, Volcanic Ash Advisory Center 

(VAAC), Australia 

11:30 AM Building on Our Successes in Aviation Safety for the Next Decade 

Dr. Elbert W. (Joe) Friday, University of Oklahoma

Dr. Paul D. Try, Senior Vice President, Science and Technology Corporation 
 A-16

12:30 PM Closing Remarks/Next Steps

 Mr. Samuel P. Williamson, Federal Coordinator for Meteorological Services and 

Supporting Research 

1:00 PM Adjourn 
B-1

APPENDIX B 

ATTENDEES 
B-2
The 2nd International Conference on Volcanic 

Ash and Aviation Safety 

Alexandria, Virginia 

June 21-24, 2004 

 B-3

Ms. Cyndie Abelman 

Meteorologist in Charge 

National Weather Service 

FAA Academy AMA-514 

P.O. Box 25082 

Oklahoma City, OK 73125-0082 

USA 

Phone: 405-954-6870 

E-mail: cyndie.abelman@noaa.gov 

Dr. Steven Ackerman 

University of Wisconsin-Madison 

1225 West Dayton Street 

Madison, WI 53706 

USA 

Phone: 608-263-3647 

E-mail: stevea@ssec.wisc.edu 

Mr. Steven Albersheim 

FAA 

800 Independence Ave, SW 

Washington, DC 20591 

USA 

Phone: 202-385-7704 

Fax: 202-385-7701 

E-mail: Steven.Albersheim@faa.gov 

Mr. Mark Andrews 

Aviation Weather Program Manager 

NOAA 

SSMC2, Rm 13308 

1325 East-West Hwy 

Silver Spring, MD 20910 

USA 

Phone: 301-713-1726 x109 

Fax: 301-713-1520 

E-mail: mark.andrews@noaa.gov 

Ms. Debi Bacon 

Air Traffic Control Specialist 

FAA 

800 Independence Ave., S.W. 

Washington, DC 20591 

USA 

Phone: 202-385-7705 

Fax: 202-385-7701 

E-mail: debi.bacon@faa.gov 

Mr. Antonio Bandaro 

Catania Airport Director 

Italian Civil Aviation Authority 

Catania via Horosoli 13 

Italy 

E-mail: a.bardaro@enze.rupa.it 

Mr. Kenneth Barnett 

OFCM 

Suite 1500 

8455 Colesville Road 

Silver Spring, MD 20910 

USA 

Phone: 301-427-2002 

Fax: 301-427-2007 

E-mail: Kenneth.Barnett@noaa.gov 

Ms. Sara Barsotti 

INGV 

Via Della Faggiiola 32 

Pisa, 56126 

ITALY 

Phone: 050-8311945 

E-mail: barsotti@pi.ingv.it 

Mr. Nigel Basheer 

Senior Computer Systems Engineer 

Tenix Defence Pty Ltd 

Technology Park 

Mawson Lakes, Second Ave 

ADELAIDE 5095, 

South Australia 

Phone: +61 8 8300 4721 

Fax: +61 8 8300 4510 

E-mail: nigel.basheer@tenix.com 

Mr. Chris Baum 

Manager, Engineering and Accident Investigator 

Air Line Pilots Assn, Intl. 

535 Herndon Parkway 

Herndon, VA 20170 

USA 

Phone: 703-689-4312 

E-mail: chris.baum@alpa.org 
The 2nd International Conference on Volcanic 

Ash and Aviation Safety 

Alexandria, Virginia 

June 21-24, 2004 

 B-4

Capt. Al Beerley 

US Airways Airbus 

1204 Old Forge Road 

Oxford, PA 196363 

USA 

Phone: 610-932-8353 

E-mail: albeerley@hotmail.com 

Dr. Karen Bemis 

IMCS, Rutgers University 

71 Dudley Road 

New Brunswick, NJ 08901-8521 

USA 

Phone: 732-445-1225 

Fax: 732-445-3374 

E-mail: bemis@rci.rutgers.edu 

Mr. Saad Benarafa 

World Meteorological Organization 

7bis avenue de la Paix, case postale 2300 

Geneva, 

Switzerland 

Phone: +41(0) 22 730 84 08 

Fax: +41 (0) 22 730 81 28 

E-mail: sbenarafa@wmo.int 

Mr. Kevin Berberich 

Summer Intern 

NOAA-NESDIS 

5200 Auth Road 

Room 401 

Camp Springs, MD 20746 

USA 

Phone: 301-763-8444 

E-mail: w-vaac@noaa.gov 

Mr. Charles Bergman 

Manager, Air Safety and Operations 

Air Line Pilots Association, Int'l 

535 Herndon Parkway 

Herndon, VA 20170 

USA 

Phone: 703-689-4188 

Fax: 703-464-2104 

E-mail: charlie.bergman@alpa.org 

Dr. Cirilo Bernardo 

CSIRO Atmospheric Research 

PMB 1 

Aspendale, Vic., 3195 

Australia 

Phone: (613) 9239 4669 

Fax: (613) 9239 4400 

E-mail: cirilo.bernardo@csiro.au 

Mr. Ronald Birk 

Director 

NASA Earth Science Applications Division 

Code YO 

300 E Street SW 

Washington, DC 20546 

USA 

Phone: 202-358-1701 

Fax: 202-358-3098 

E-mail: ronald.j.birk@hq.nasa.gov 

Dr. Gregg Bluth 

Michigan Technological University 

1400 Townsend Drive 

Houghton, MI 49931 

USA 

Phone: 906-487-3554 

E-mail: gbluth@mtu.edu 

Mr. Gary Bobik 

FAA 

800 Independence Ave. SW 

Washington, DC 20591 

USA 

Phone: 202-267-9754 

Fax: 202-493-5016 

E-mail: gary.bobik@faa.gov 

Ms. Betty Bollert 

Dispatch Instructor 

Alaska Airlines 

P O Box 68900 

Seattle, WA 98168 

USA 

Phone: 206-431-7655 

E-mail: betty.bollert@alaskaair.com 
The 2nd International Conference on Volcanic 

Ash and Aviation Safety 

Alexandria, Virginia 

June 21-24, 2004 

 B-5

Dr. Costanza Bonadonna 

University of Hawaii 

1680 East-West Road 

POST Building 617a 

Honolulu, HI 96822 

USA 

Phone: 808 956 5033 

Fax: 808 956 5512 

E-mail: costanza@hawaii.edu 

Mr. Stephen Boulter 

Screenwriter 

Larimer Productions 

5349 Promontory Circle 

Ft. Collins, CO 80528 

USA 

Phone: 303-668-0515 

E-mail: SKBoulter@msn.com 

Mr. Alonzo Brown 

Meteorologist 

NOAA/NESDIS/SSD/SAB 

5200 Auth Rd 

Rm 401 

Camp Springs, MD 20746 

USA 

Phone: 301-763-8444 

E-mail: Alonzo.Brown@noaa.gov 

Ms. Mary M. Cairns 

Senior Staff Meteorologist 

OFCM 

8455 Colesville Road 

Suite 1500 

Silver Spring, MD 20910 

USA 

Phone: 301-427-2002 

Fax: 301-427-2007 

E-mail: Mary.Cairns@noaa.gov 

Mr. Mike Campbell 

Deputy Director/Chief International Operations 

NWS/NCEP 

Aviation Weather Center 

Kansas City, MO 64153-2371 

USA 

Phone: 816-584-7203 

Fax: 816-880-0650 

E-mail: mike.campbell@noaa.gov 

Dr. Bruce Carmichael 

Manager of Aviation Weather Research 

National Center for Atmospheric Research 

P.O. Box 3000 

Boulder, CO 80301 

USA 

Phone: 303-497-8406 

Fax: 303-497-8401 

E-mail: brucec@ucar.edu 

Dr. Simon Carn 

University of Maryland Baltimore County 

1000 Hilltop Circle 

Baltimore, MD 21250 

USA 

Phone: 410-455-1454 

Fax: 410-455-5868 

E-mail: scarn@umbc.edu 

Mr. Donald "Doc" Carver 

FAA/OFCM 

8455 Colesville Road 

Silver Spring, MD 20910 

USA 

Phone: 301-427-2002 

Fax: 301-427-2007 

E-mail: donald.carver@noaa.gov 

Mr. John Chadwick 

Idaho State University 

Pocatello, ID 83211 

USA 

Phone: 208-282-2949 

E-mail: chadjohn@isu.edu 

Mr. Peter Chen 

Director, Operations 

Canadian Meteorological Center 

Environment Canada 

2121 Trans-Canada Highway 

Dorval, Quebec 

Canada 

Phone: 514-421-4622 

Fax: 514-421-4679 

E-mail: peter.chen@ec.gc.ca 
The 2nd International Conference on Volcanic 

Ash and Aviation Safety 

Alexandria, Virginia 

June 21-24, 2004 

 B-6

Mr. Daniel Chrétien 

Aviation Meteorologist 

NAV Canada 

77 Metcalfe #518 

Ottawa, ON K1P 5L6 

Canada 

Phone: 613-563-5607 

Fax: 613-563-5602 

E-mail: chretid@navcanada.ca 

Ms. Pam A. Clark 

Acting Division Chief 

U.S. Army Research Laboratory 

ATTN: AMSRD-ARL-CI-EE (P. Clark) 

2800 Powder Mill Road 

Adelphi, MD 20783 

USA 

Phone: 301-394-3447 

Fax: 301-394-4797 

E-mail: pclark@arl.army.mil 

Col. Richard Clayton 

Deputy Director of Weather 

USAF 

HQ USAF/XOO-W 

1490 Air Force Pentagon 

Washington, DC 20330-1490 

Phone: 703-614-7258 

Fax: 703-614-0055 

E-mail: richard.clayton@pentagon.af.mil 

Dr. Mauro Coltelli 

Scientist 

INGV 

Piazza Roma 2 

Catania, 95123 

Italy 

Phone: +39 095 7165850 

E-mail: coltelli@ct.ingv.it 

Dr. Bernadette Connell 

Research Scientist 

CIRA/CSU 

1375 Campus Delivery 

Fort Collins, CO 80523-1375 

USA 

Phone: 970-491-8689 

Fax: 970-491-8241 

E-mail: connell@cira.colostate.edu 

Mr. Luigi Cornaglia 

Investigation Manager 

ALITALIA 

Via P.P. Racchetti 

Airport Fiumicino 

Rome 50, 

Italy 

Phone: 0039-06-65638380 

E-mail: cornaglia.luigi@alitalia.it 

Dr. Antonio Costa 

OV-INGV 

Via Diocleziano, 328 

Napoli, I-80124 

Italy 

Phone: 0039 0816108335 

Fax: 0039 0816108351 

E-mail: costa@ov.ingv.it 

Captain John M. Cox 

Executive Air Safety Chairman 

Air Line Pilots Association 

4463 - 39th Street South 

St. Petersburg, FL 33711 

USA 

Phone: 727-515-1061 (cell) 

Fax: 727-866-2268 

E-mail: john.cox@alpa.org 

Dr. Paola Del Carlo 

INGV-Catania 

Piazza Roma 2 

Catania, 95123 

ITALY 

Phone: 0039 95 7165800 

E-mail: delcarlo@ct.ingv.it 

Mr. Peter Dempster 

Intl Dispatcher 

US Airways 

173 industry Dr 

Pittsburgh, PA 15275 

USA 

Phone: 412-747-5630 

Fax: 412-747-1498 

E-mail: peter_d_dempster@usairways.com 
The 2nd International Conference on Volcanic 

Ash and Aviation Safety 

Alexandria, Virginia 

June 21-24, 2004 

 B-7

Mr. Larry Denton 

The Weather Channel 

300 Interstate N. Parkway 

Atlanta, GA 30328 

USA 

E-mail: larry.denton@weather.com 

Mr. Jean-Philippe Desbios 

VAAC Representative 

Meteo France 

42 Avenue 

G Coriolis 

Toulouse, 31057 cedex 

FRANCE 

Phone: 33 561-07-83-30 

Fax: 33-561 07 82 54 

E-mail: jean-Philippe.desbios@meteo.fr 

Mr. J. Gary DiNunno 

Editor-in-Chief 

Air Line Pilots Association 

PO Box 1169 

Herndon, VA 20172 

Phone: 703-481-4460 

Fax: 703-464-2114 

E-mail: gary.dinunno@alpa.org 

Prof. Eric Doten 

Director 

Embry-Riddle 

600 Clyde Morris Blvd 

Daytona Beach, FL 32114 

USA 

Phone: 386-323-5064 

Fax: 386-226-6895 

E-mail: ericsd@aol.com 

Dr. Eliecer Duarte 

Professor 

Observatorio Vulcanologico y Sismologico de 

Costa Rica 

Campus, Universidad Nacional 

Heredia, 

Costa Rica 

Phone: 506-261-0781 

Fax: 506-261 0303 

E-mail: eduarte@una.ac.cr 

Mr. Paula Dunbar 

Physical Scientist 

National Geophysical Data Center 

NOAA E/GC1 

325 Broadway 

Boulder, CO 80305 

USA 

Phone: 303-497-6084 

Fax: 303-497-6513 

E-mail: Paula.Dunbar@noaa.gov 

Col. (Sel) Harold A. Elkins 

Chief, Weather Plans Division 

USAF 

1490 Air Force Pentagon 

Washington, DC 20330 

USA 

Phone: 703-696-4936 

E-mail: afxowx@pentagon.af.mil 

Mr. Gary Ellrod 

Meteorologist 

NOAA/NESDIS 

Room 712, E/RA2, WWBg 

5200 Auth Road 

Camp Springs, MD 20746 

USA 

Phone: 301-763-8204 x 140 

Fax: 301-763-8580 

E-mail: Gary.Ellrod@noaa.gov 

Ms. Dawn Erlich 

STC 

1010 Wayne Avenue, Suite 450 

Silver Spring, MD 20910 

USA 

Phone: 301-565-8345 

Fax: 301-565-8279 

E-mail: stc.ss@stcnet.com 

Dr. Gerald Ernst 

University of Ghent 

Krijgslaan 281-S8 

Gent, B-9000 

Belgium 

Phone: +32.9264.4633 

Fax: +32.9264.4943 

E-mail: plumeman2000@yahoo.co.uk 
The 2nd International Conference on Volcanic 

Ash and Aviation Safety 

Alexandria, Virginia 

June 21-24, 2004 

 B-8

Lt. Col. Frank Estis 

OFCM 

8455 Colesville Rd., Suite 1500 

Silver Spring, MD 20910 

USA 

Phone: 301-427-2002 

Fax: 301-427-2007 

E-mail: frank.estis@noaa.gov 

Mr. William "Bill" Euille 

Mayor, Alexandria, Virginia 

City of Alexandria 

301 King Street 

Alexandria, VA 22314 

USA 

Mr. John Ewert 

U.S. Geological Survey 

1300 SE Cardinal Ct., #100 

Vancouver, WA 98683 

USA 

Phone: 360-993-8912 

Fax: 360-993-8980 

E-mail: jwewert@usgs.gov 

Mr. Wayne Feltz 

University of Wisconsin 

1225 W. Dayton 

Rm 235 

Madison, WI 53706 

USA 

Phone: 608-265-6283 

E-mail: waynef@ssec.wisc.edu 

Ms. Gail Ferguson 

Operations Manager 

FAA 

700 N Boniface Parkway 

Anchorage, AK 99506 

USA 

Phone: 907-269-1250 

Fax: 907-269-1343 

E-mail: gail.ferguson@faa.gov 

Mr. Gustavo Alberto Flores 

Manager 

VAAC Buenos Aires 

25 de mayo 658 

Capital Federal 

Buenos Aires, 1002ABN 

Argentina 

Phone: 54-11-5-167-6707 

Fax: 54-11-5-167-6709 

E-mail: gflores@meteofa.mil.ar 

Dr. Gregory S. Forbes 

Severe Weather Expert 

The Weather Channel 

300 Interstate N. Parkway 

Atlanta, GA 30328 

USA 

E-mail: greg.forbes@weather.com 

Mr. Thomas Fraim 

OFCM 

8455 Colesville Road 

Suite1500 

Silver Spring, MD 20910 

USA 

Phone: 301-427-2002 

Fax: 301-427-2007 

E-mail: thomas.fraim@noaa.gov 

Dr. Elbert W. Friday 

Professor 

University of Oklahoma 

100 East Boyd St. SEC Suite 1310 

Norman, OK 73019 

USA 

Phone: 571-215-8022 

Fax: 202-334-3825 

E-mail: joefriday@ou.edu 

Mr. Nigel Gait 

Met Office 

B1-57 

Fitzroy Road 

Eastleigh, EX13PB 

United Kingdom 

Phone: -887616 

E-mail: nigel.gait@metoffice.com 
The 2nd International Conference on Volcanic 

Ash and Aviation Safety 

Alexandria, Virginia 

June 21-24, 2004 

 B-9

Mr. Gregory M. Gallina 

Meteorologist 

NOAA/NESDIS/SAB 

5200 Auth Road 

Rm. 401 

Camp Springs, MD 20746-4304 

USA 

Phone: 301-763-8444 

Fax: 301-763-8333 

E-mail: Greg.Gallina@noaa.gov 

Ms. Cynthia Gardner 

U.S. Geological Survey 

1300 SE Cardinal Ct. 

Bldg 10 

Vancouver, WA 98683 

USA 

Phone: 360-993-8914 

Fax: 360-993-8980 

E-mail: cgardner@usgs.gov 

Mr. Alexander Giarrocco 

Flight Dispatch Officer 

Spirit Airlines Inc. 

2800 Executive Way 

Miramar, FL 33025 

USA 

Phone: 954 447 8051 

Fax: 954 447 7852 

E-mail: sallyc@spiritair.com 

Mr. Ellis Godfrey 

NOAA Coastal Services Center 

2234 S. Hobson Avenue 

Charleston, SC 29405 

USA 

Phone: 843-740-1257 

E-mail: ellis.godfrey@noaa.gov 

Capt. Richard Gonzalez 

Air Force Weather Agency 

Offutt AFB, NE 68113-4039 

USA 

Phone: 402-294-9759 

Fax: 

E-mail: richard.gonzalez@afwa.af.mil 

Dr. Evgenii Gordeev 

Director 

Institute of Volcanology and Seismology 

Piip Blvd. 9 

Petropavlovsk-Kamchatsky, 683006 

Russian Federation 

Phone: 415-22-59530 

E-mail: gord@emsd.iks.ru 

Mr. Steve Graham 

NASA/GSFC 

Bldg. 33, Rm E112 

Greenbelt, MD 20771 

USA 

Phone: 301-614-5561 

Fax: 301-614-6530 

E-mail: graham@pop900.gsfc.nasa.gov 

Dr. David Green 

NOAA/NWS 

1325 East-West Highway 

Silver Spring, MD 20910 

USA 

Phone: 301-713-3557 

E-mail: david.green@noaa.gov 

Mr. Thomas Grindle 

Aerospace Engineer 

NASA Dryden Flight Research Center 

P.O. Box 273 

MS: D-2708 

Edwards, CA 93523-0273 

USA 

Phone: 661-276-2710 

Fax: 661-276-3744 

E-mail: tom.grindle@dfrc.nasa.gov 

Dr. Charles G. Groat 

Director 

U.S. Geological Survey 

2201 Sunrise Valley Drive 

Reston, VA 20192 

USA 

E-mail: groat@usgs.gov 
The 2nd International Conference on Volcanic 

Ash and Aviation Safety 

Alexandria, Virginia 

June 21-24, 2004 

 B-10

Ms. Marianne Guffanti 

Geologist 

U.S. Geological Survey 

926A National Center 

Reston, VA 20192 

USA 

Phone: 703-648-6708 

Fax: 703-648-5483 

E-mail: guffanti@usgs.gov 

Dr. Reinaldo Gutierrez 

Direccion Meteorologica de Chile 

Casilla N 63 internacional 

Santiago, 

Chile 

Phone: 56-02-6763461 

E-mail: rgutierrez@meteochile.cl 

Mr. Shahid Habib 

NASA/GSFC 

Code 900 

Greenbelt, MD 20771 

USA 

Phone: 301-614-5392 

Fax: 301-614-5620 

E-mail: shahid.habib-1@nasa.gov 

Mr. Keith Hagy 

Assoc. Director 

ALPA 

535 Herndon Parkway 

Herndon, VA 20170 

USA 

Phone: 703-689-4206 

E-mail: keith.hagy@alpa.org 

Mr. William Harrison 

USA Aeronautical Services Agency 

9325 Gunston Road, Bldg 1466 

Suite N319 

Fort Belvoir, VA 22060-5582 

USA 

Phone: 703-806-4871 

Fax: 703-806-4409 

E-mail: William_T_Harrison@belvoir.army.mil 

Mr. Floyd Hauth 

STC 

Suite 450 

1010 Wayne Avenue 

Silver Spring, MD 20910 

USA 

Phone: 301-565-8345 

Fax: 301-565-8279 

E-mail: fhauth@netphd.net 

Mr. John Haynes 

Program Manager 

NASA HQ 

Code YO 

300 E Street, SW 

Washington, DC 20546 

USA 

Phone: 202-358-4665 

Fax: 202-358-3098 

E-mail: jhaynes@hq.nasa.gov 

Mr. Jerome Heffter 

NOAA-ARL (R-ARL) 

1315 Eastwest Hwy 

Silver Spring, MD 20910 

USA 

Phone: 301-713-0295 

E-mail: jheffter@comcast.net 

Dr. Rosalind Helz 

U.S. Geological Survey 

M.S. 926A 

Reston, VA 20192 

USA 

Phone: 703-648-6086 

E-mail: rhelz@usgs.gov 

Mr. Richard Hernandez 

FAA 

5000 Carr 190 

Carolina, PR 00979-7440 

USA 

Phone: 787-253-8707 

Fax: 787-253-8709 

E-mail: Richard.Hernandez@faa.gov 
The 2nd International Conference on Volcanic 

Ash and Aviation Safety 

Alexandria, Virginia 

June 21-24, 2004 

 B-11

Mr. Sierra Herson 

Meteorologist 

Direccion General de Aeronautica Civil 

Bloque B, casa 705 

Tegucigalpa, Apdo 30145 

Honduras 

Phone: 504-233-8075 

Fax: 504-233-8075 

E-mail: hhsierras@latinmail.com 

Dr. Paul Herzegh 

Project Scientist 

National Center for Atmospheric Research 

PO Box 3000 

Boulder, CO 80307 

USA 

Phone: 303-497-2820 

E-mail: herzegh@ucar.edu 

Mr. Richard Heuwinkel 

FAA 

1575 Eye St, NW 

Washington, DC 20005 

USA 

Phone: 202-385-7696 

E-mail: Richard.Heuwinkel@faa.gov 

Dr. Catherine Hickson 

Volcanologist 

Natural Resources Canada 

101 - 605 Robson Street 

Vancouver, BC V6B 5J3 

Canada 

Phone: 604 666-9772 

Fax: 604 666-7507 

E-mail: chickson@nrcan.gc.ca 

Mr. Charles Holliday 

Chief, METSAT Applications Branch 

Air Force Weather Agency 

AFWA/XOGM 

106 Peacekeeper Dr 

Offutt AFB, NE 68113-4039 

USA 

Phone: 402-294-9756 

Fax: 402-294-5872 

E-mail: charles.holliday@afwa.af.mil 

Mr. David Hook 

Aircraft Dispatcher 

Frontier Airlines 

7001 Tower Rd 

Denver, CO 80249-7312 

USA 

Phone: 720-374-4545 

Fax: 720-374-4385 

E-mail: dhook@flyfrontier.com 

Dr. Linda Huey 

Program Assistant 

U.S. Geological Survey 

904 National Center 

Reston, VA 20192 

USA 

Phone: 703-648-6712 

Fax: 703-648-5483 

E-mail: lhuey@usgs.gov 

Ms. Winnie H. Humberson 

Outreach Coordinator 

NASA/GSFC 

Bldg. 33, Rm. E112 

Greenbelt, MD 20771 

USA 

Phone: 301-6145560 

Fax: 301-6146530 

E-mail: winnie.h.humberson.1@gsfc.nasa.gov 

Ms. Harmony Hunter 

STC 

10 Basil Sawyer Dr. 

Hampton, VA 23666-1393 

USA 

Phone: 757-864-3297 

Fax: 757-864-8810 

E-mail: h.a.hunter@larc.nasa.gov 

Capt. David Innes 

Air Niugini 

P.O Box 7186 

Boroko 

Port Moresby, 

Papua New Guinea 

Phone: (675)3273581 

Fax: (675)3273454 

E-mail: deejayinnes@yahoo.com 
The 2nd International Conference on Volcanic 

Ash and Aviation Safety 

Alexandria, Virginia 

June 21-24, 2004 

 B-12

Mr. Pavel Izbekov 

Alaska Volcano Observatory 

903 Koyukuk Drive 

Fairbanks, AK 99775 

USA 

Phone: 907-474-5269 

E-mail: pavel@gi.alaska.edu 

Mr. Douglas Jenkins 

Operations Training and Standards 

FedEx 

Module F 

3865 Airways 

Memphis, TN 38116-0517 

USA 

Phone: 901-224-7429 

E-mail: dgjenkins@fedex.com 

Dr. David Johnson 

National Center for Atmospheric Research 

P.O. Box 3000 

Boulder, CO 80307 

USA 

Phone: 303-497-8370 

Fax: 303-497-8401 

E-mail: djohnson@ucar.edu 

Dr. Sigrun Karlsdottir 

Icelandic Meteorological Office 

Bustadarvegur 9 

Reykjavik, IS-150 

Iceland 

Phone: +354 522600 

Fax: +354 522 6001 

E-mail: sigk@vedur.is 

Dr. Terry E. Keith 

U.S. Geological Survey 

4200 University Drive 

Anchorage, AK 99508-4667 

USA 

Phone: 907-786-7456 

Fax: 907-786-7425 

E-mail: tkeith@doodlepig.com 

Mr. Frank Kelly 

NOAA/NWS 

1325 East-West Highway 

Silver Spring, MD 20910 

USA 

Phone: 301-713-7400 x126 

E-mail: Frank.Kelly@noaa.gov 

Mrs. Cathy Kessinger 

NCAR/RAP 

3450 Mitchell Lane 

Boulder, CO 80301 

USA 

Phone: 202-497-8481 

E-mail: kessinger@ucar.edu 

Mr. Jamie Kibler 

NOAA/SAB 

5200 Auth Road 

Room 401 

Camp Springs, MD 20746 

USA 

Phone: 301-763-8444 

Fax: 301-763-8333 

E-mail: Jamie.Kibler@noaa.gov 

Dr. Kisei Kinoshita 

Professor 

Kagoshima University 

Korimoto 1-20-6 

Kagoshima 890-0065, 

JAPAN 

Phone: 81-99-285-7803 

Fax: 81-99-285-7735 

E-mail: kisei@edu.kagoshima-u.ac.jp 

Mr. Takeshi Koizumi 

Deputy Director 

Japan Meteorological Agency 

Ote-machi, Chiyoda 

Tokyo 1008122, 

Japan 

Phone: 81332841749 

Fax: 81332123648 

E-mail: t-koizumi@met.kishou.go.jp 
The 2nd International Conference on Volcanic 

Ash and Aviation Safety 

Alexandria, Virginia 

June 21-24, 2004 

 B-13

Dr. Arlin Krueger 

Professor 

JCET/UMBC 

1000 Hilltop Circle 

Baltimore, MD 21250 

USA 

Phone: 410-455-8906 

E-mail: akrueger@umbc.edu 

Ms. Gloria Kulesa 

FAA 

475 School St, SW 

Washington, DC 20024 

USA 

Phone: 202-267-7289 

E-mail: Gloria.Kulesa@faa.gov 

Mr. Kent Laborde 

NOAA 

14th and Constitution Ave, NW 

Washington, DC 20230 

USA 

Phone: 202-482-5757 

Fax: 202-482-3154 

E-mail: kent.labored@noaa.gov 

Dr. Judson Ladd 

Chief 

National Weather Service 

819 Taylor St. 

Room 10E09 

Fort Worth, TX 76102 

USA 

Phone: 817-978-1100 

Fax: 817-978-4920 

E-mail: Judson.Ladd@noaa.gov 

Mr. Marc Lamy 

Manager, Investment Analysis 

Tenix Investments Pty Ltd 

100 Arthur Street 

North Sydney NSW, 2060 

Australia 

Phone: 612 9963 9672 

Fax: 612 9963 9691 

E-mail: marc.lamy@tenix.com 

Mr. Patrick Leahy 

Associate Director for Geology 

U.S. Geological Survey 

12201 Sunrise Valley Drive 

Mail Stop 911 

Reston, VA 20192 

USA 

Phone: 703-648-6600 

Fax: 703-648-7031 

E-mail: pleahy@usgs.gov 

Mr. Peter Lechner 

Civil Aviation Authority of New Zealand 

PO Box 31 441 

Lower Hutt 

Wellington, 

New Zealand 

Phone: +64 4 560 9593 

Fax: +64 4 569 2024 

E-mail: lechnerp@caa.govt.nz 

Mr. Tenny Lindholm 

Manager 

National Center for Atmospheric Research 

3450 Mitchell Lane 

Boulder, CO 80301 

USA 

Phone: 303-497-8448 

Fax: 303-497-8401 

E-mail: mcgaffic@ucar.edu 

Cpt. Franco Lodi 

Ansv 

Via Attilio Benigni, 53 

Roma, 156 

Italy 

Phone: +39 06 82078 200 

Fax: +39 06 8273672 

E-mail: franco.lodi@ansv.it 

Mr. Jim Luhr 

Smithsonian Institution 

P.O. Box 37012 

NHB-119 

Washington, DC 20013 

USA 

Phone: 202-357-4809 

Fax: 202-357-2476 

E-mail: luhr@volcano.si.edu 
The 2nd International Conference on Volcanic 

Ash and Aviation Safety 

Alexandria, Virginia 

June 21-24, 2004 

 B-14

Dr. Giovanni Macedonio 

Osservatorio Vesuviano 

Via Diocleziano, 328 

Napoli, I-80124 

Italy 

Phone: +39 081 6108 482 

Fax: +39 081 6102 304 

E-mail: macedon@ov.ingv.it 

Dr. James R. Mahoney 

Assistant Secretary of Commerce for Oceans and 

Atmosphere and NOAA Deputy Administrator 

14th and Constitution Ave. 

Washington, DC 20230 

USA 

E-mail: James.Mahoney@noaa.gov 

Mr. Fausto César Mancero Jiménez 

Subdirección de Aviación Civil del Ecuador 

Simón Bolívar, Ave. Las Américas 

Guayaquil, N/A 

Ecuador 

Phone: 593-4-2392712 

Fax: 593-4-2283748 

E-mail: fmancero@hotmail.com 

Ms. Alexandra Matiella 

Graduate Student 

Michigan Technological University 

630 Dow 

1400 Townsend Dr. 

Houghton, MI 49931 

USA 

Phone: 906-487-3097 

E-mail: Mamatiel@mtu.edu 

Dr. Mike Matson 

Deputy Director, OSDPD 

NOAA/NESDIS 

FB4, Room 1069 

Suitland, MD 20749 

USA 

Phone: 301-457-5120 

E-mail: michael.matson@noaa.gov 

Mr. Gari Mayberry 

Geologist 

U.S. Geological Survey 

NMNH E-421 

Washington, DC 20560-0119 

USA 

Phone: 202-357-2618 

Fax: 202-357-2476 

E-mail: mayberry@volcano.si.edu 

Dr. Emily McCarthy 

MTU-GMES 

1400 Townsend Dr 

Houghton, MI 49931 

USA 

Phone: 906-487-1761 

E-mail: ebmccart@mtu.edu 

Mr. David McCormack 

Geological Survey of Canada 

7 Observatory Crescent 

Ottawa, ON K1A 0Y3 

Canada 

Phone: 613-992-8766 

E-mail: cormack@seismo.nrcan.gc.ca 

Mr. Mark McCrady 

Environment Canada 

2121 Transcanada Hwy 

Dorval, QC H9P-1J3 

Canada 

Phone: 514-421-4635 

Fax: 514-421-4679 

E-mail: mark.mccrady@ec.gc.ca 

Mr. Walter McKeown 

Senior Scientist 

U.S. Navy 

9141 Third Avenue 

Norfolk, VA 23511 

USA 

Phone: 757-445-2546 

Fax: 757-444-7343 

E-mail: walt.mckeown@nlmoc.navy.mil 
The 2nd International Conference on Volcanic 

Ash and Aviation Safety 

Alexandria, Virginia 

June 21-24, 2004 

 B-15

Ms. Erin McNamara 

OFCM 

8455 Colesville Road 

Suite 1500 

Silver Spring, MD 20910 

USA 

Phone: 301-427-2002 

Fax: 301-427-2007 

E-mail: Erin.McNamara@noaa.gov 

Dr. Stephen McNutt 

AVO 

P.O. Box 757320 

Fairbanks, AK 99775-7320 

USA 

Phone: 907-474-7131 

Fax: 907-474-5618 

E-mail: steve@giseis.alaska.edu 

Captain Terry McVenes 

Executive Air Safety Vice-Chairman 

Air Line Pilots Association 

535 Herndon Parkway 

Herndon, VA 20170 

USA 

Phone: 703-481-2432 

Fax: 303-530-3608 

E-mail: terry.mcvenes@alpa.org 

Mr. Peter Meister 

NASA Headquarters 

Code Y 

Washington, DC 20546 

USA 

Phone: 202-358-1557 

Fax: 202-358-3098 

E-mail: peter.g.meister@nasa.gov 

Capt. Ed Miller 

Air Line Pilots Association, Int'l 

Herndon, VA 20170 

USA 

Phone: 703-689-4187 

Fax: 703-464-2104 

E-mail: millere@alpa.org 

Dr. Thomas P. Miller 

U.S. Geological Survey 

4200 University Drive 

Anchorage, AK 99508 

USA 

Phone: 907-786-7454 

Fax: 907-786-7425 

E-mail: tmiller@usgs.gov 

Dr. Cecilia Miner 

Senior Systems Analyst 

AvMet Applications International 

2300 Clarendon Blvd, Suite 1107 

Arlington, VA 22201 

USA 

Phone: 703-351-5659 

Fax: 703-351-5645 

E-mail: miner@avmet.com 

Capt. Eric Moody 

British Airways (Ret.) 

14 Crosby Hill Drive 

Camberley, Surrey, GU15 3TY 

United Kingdom 

Phone: 01276 24562 

Fax: 01276 24562 

E-mail: eric@ericmoody.com 

Ms. Patricia Mothes 

Instituto Geofisico 

Casilla 1701-2759 

Quito, 1701-2759 

Ecuador 

Phone: (593-2)2225-655 

(593-2)227-031 

Fax: (593-2) 2567-847 

E-mail: patriciamothes@hotmail.com 

Mr. Greg Mullen 

American Airlines 

4601 Hwy 360 

Md 875 

Ft. Worth, TX 76155 

USA 

Phone: 817-967-7200 

Fax: 817-967-7090 

E-mail: lv2flyaa@earthlink.net 
The 2nd International Conference on Volcanic 

Ash and Aviation Safety 

Alexandria, Virginia 

June 21-24, 2004 

 B-16

Mr. John Murray 

Atmospheric Scientist 

NASA 

21 Langley Blvd 

Hampton, VA 23669 

USA 

Phone: 757-864-5883 

E-mail: John.J.Murray@nasa.gov 

Dr. Tom Murray 

Scientist in Charge 

Alaska Volcano Observatory 

4200 University Drive 

Anchorage, AK 99508 

USA 

Phone: 907-786-7443 

Fax: 907-786-7425 

E-mail: tlmurray@usgs.gov 

Ms. Christina Neal 

U.S. Geological Survey 

4200 University Drive 

Anchorage, AK 99508 

USA 

Phone: 907-786-7458 

Fax: 907-786-7425 

E-mail: tneal@usgs.gov 

Dr. Augusto Neri 

Researcher 

Instituto Nazionale di Geofisica e Vulcanologia 

via della Faggiola 32 

Pisa I-56126, 

ITALY 

Phone: 8311941 

Fax: 

E-mail: neri@pi.ingv.it 

Mr. Gregory Neuman 

Department of Defense 

1000 6th St SW, Apt 512 

Washington, DC 20024 

USA 

Phone: 202-285-2829 

E-mail: greg@gregneuman.com 

Mr. Chris Newhall 

U.S. Geological Survey 

Box 351310 

Seattle, WA 98195 

USA 

Phone: 206-553-6986 

Fax: 206-543-0489 

E-mail: cnewhall@usgs.gov 

Mr. John O'Brien 

Airline Pilots Association 

535 Herndon Parkway 

Herndon, VA 20170 

USA 

Phone: 703-689-4200 

Fax: 703-464-2104 

E-mail: JOHN.OBRIEN@ALPA.ORG 

Mr. Giles OKeeffe 

President 

ADF 

2720 Ashbourne Rd 

Wayzata, MN 55391 

USA 

Phone: 612-727-0295 

Fax: 612-727-0382 

E-mail: giles.okeeffe@nwa.com 

Mr. Saburo Onodera 

Manager, Flight Crew Training Dept. 

Japan Airlines 

JAL Technical Center 2 

Haneda Airport 

Ota-ku, Tokyo, 144-0041 

Japan 

Phone: 81-3-5756-3931 

Fax: 81-3-5756-3596 

E-mail: saburo.onodera@jal.com 

Mr. Jeffrey Osiensky 

Meteorologist in Charge 

National Weather Service 

6930 Sand Lake Road 

Anchorage, AK 99645 

USA 

Phone: 907-266-5116 

Fax: 907-266-5182 

E-mail: jeffrey.osiensky@noaa.gov 
The 2nd International Conference on Volcanic 

Ash and Aviation Safety 

Alexandria, Virginia 

June 21-24, 2004 

 B-17

Dr. Kenneth Papp 

Alaska Volcano Observatory 

903 Koyukuk Drive 

Fairbanks, AK 99775 

USA 

Phone: 907-474-1925 

E-mail: kpapp@gi.alaska.edu 

Mr. Herman Patia 

Rebaul Volcano Observatory 

PO Box 386 

Rebaul, 

Papua New Guinea 

Phone: 675-92-1699 

E-mail: hguria@global.net.pg 

Dr. Vincenzo Pennetta 

ANSV 

Via Attilio Benigni,53 

Roma 156, 

Italy 

Phone: +39 06 82078238 

Fax: +39 06 8293943 

E-mail: vincenzo.pennetta@ansv.it 

Mr. Rorik Peterson 

University of Alaska, Fairbanks 

903 Koyukuk Drive 

PO Box 757320 

Fairbanks, AK 99709 

USA 

Phone: 907-474-1519 

E-mail: ffrap1@aurora.uaf.edu 

Mr. Bill Phaneuf 

Air Line Pilots Association, Intl 

535 Herndon Parkway 

Herndon, VA 20170 

USA 

Phone: 703-689-4388 

Fax: 703-464-2104 

E-mail: phaneufb@alpa.org 

Mr. Errico Picciotti 

University of L'Aquila (Italy) 

via Vetoio No 1 

67010 L'Aquila, 

Italy 

Phone: 39-0862-433708 

E-mail: errico.picciotti@aquila.infn.it 

Dr. Dave Pieri 

JPL/Caltech 

MS 183-501 

4800 Oak Grove Dr. 

Pasadena, CA 91109 

USA 

Phone: 818-354-6299 

Fax: 818-354-0966 

E-mail: dave.pieri@jpl.nasa.gov 

Mr. Rodney Potts 

Bureau of Meteorology Research Centre 

GPO Box 1289K 

Melbourne VIC, 3149 

Australia 

Phone: 61-3-96694584 

Fax: 61-3-96694660 

E-mail: r.potts@bom.gov.au 

Dr. Fred Prata 

CSIRO 

107-121 Station Street 

Aspendale, Vic 3195 

Australia 

Phone: +61 3 9239 4681 

Fax: +61 3 9239 4444 

E-mail: fred.prata@csiro.au 

Mr. Greg Pratt 

DOC/NOAA/FSL 

325 Broadway, R/FS5 

Boulder, CO 80305 

USA 

Phone: 303-497-7237 

Fax: 303-497-6301 

E-mail: Greg.Pratt@noaa.gov 
The 2nd International Conference on Volcanic 

Ash and Aviation Safety 

Alexandria, Virginia 

June 21-24, 2004 

 B-18

Mr. Rudolfo Pua 

Director 

Commonwealth of the Northern Mariana Islands 

PO Box 1007 CK 

670-322-8001, 670-322-7743 

96950 Saipan 

E-mail: mpua@cnmiemo.gov.mp 

Mr. Warren Qualley 

Director, Aviation Services 

Weathernews Americas 

1218B West Rock Creek Rd 

Norman, OK 73069 

USA 

Phone: 405-701-8922 

Fax: 405-701-8901 

E-mail: warren.qualley@wni.com 

Dr. James Quick 

Coordinator, Volcano Hazards Program 

U.S. Geological Survey 

12201 Sunrise Valley Drive 

Mail Stop 904 

Reston, VA 20192 

USA 

Phone: 703-648-6711 

Fax: 703-648-5483 

E-mail: jquick@usgs.gov 

Mr. Dick Reynolds 

Prin Systems Architect 

Short and Associates 

12 Woodlawn Ave 

Annapolis, MD 21401 

USA 

Phone: 410-268-5630 

E-mail: Dick.Reynolds@noaa.gov 

Ms. Carmelitta Riley 

STC 

1010 Wayne Ave, Suite 450 

Silver Spring, MD 20910 

USA 

Phone: 301-565-8345 

Fax: 301-565-8279 

E-mail: stc.ss@stcnet.com 

Mr. Cliff Riley 

International Flight Dispatcher 

Continental Airlines 

1600 Smith St. 

HQSDC, 13th floor 

Houston, TX 77002 

USA 

Phone: 713-324-7500 

Fax: 713-324-4615 

E-mail: criley02@coair.com 

Mr. David Rodenhuis 

FAA/ATCSCC 

13600 EDS Drive, Ste 100 

Herndon, VA 22170 

USA 

E-mail: david.rohenhuis@faa.gov 

Mr. Humberto Rodriguez 

SENEAM 

Blvd. Puerto Aereo No. 485 

Col. Moctezuma 

Mexico, D. F., 7570 

Mexico 

Phone: (55) 5786-0804 

Fax: (55) 5786-0820 

E-mail: jrodrigu@sct.gob.mx 

Mr. Raul Romero 

Technical Officer MET 

ICAO 

999 University Street 

Montreal, QC H3C5H7 

Canada 

Phone: (514) 9548219 Ext 70079 

Fax: (514)9546759 

E-mail: rromero@icao.int 

Prof. William Rose 

Michigan Technological University 

Houghton, MI 49931 

USA 

Phone: 906 487-2367 

Fax: 906 487-3371 

E-mail: raman@mtu.edu 
The 2nd International Conference on Volcanic 

Ash and Aviation Safety 

Alexandria, Virginia 

June 21-24, 2004 

 B-19

Mr. Robert Ruiz 

AMTI/Supporting FAA AFS-410 

470 L’Enfant Plaza 

Suite 4102 

Washington, DC 20024 

USA 

Phone: 202-385-4578 

Fax: 202-385-4653 

E-mail: Robert.M-CTR.Ruiz@faa.gov 

Dr. Alexander Rybin 

Volcanologist 

Institute of Marine Geology and Geochemistry 

Nauki Street 

Yuzhno-Sakhalinsk, 693022 

Russian Federation 

Phone: (4242)791667 

Fax: (4242)791517 

E-mail: rybin@imgg.ru 

Mr. Jose Saballos 

INETER 

Frente a Ploclinica 

Oriental del INSS 

Managua, 2110 

Nicaragua 

Phone: +505 2492761 

Fax: +505 2491082 

E-mail: asaballos.gf@ineter.gob.ni 

Mr. Leonard Salinas 

Manager, Q/A Flight Dispatch and Operations 

United Airlines 

P.O. Box 66100 

Chicago, IL 60666 

USA 

Phone: 1-847-700-3707 

Fax: 1-847-364-0717 

E-mail: leonard.salinas@united.com 

Mr. Eddy Sanchez 

Instituto Nacional de Sismologia 

Guatemala City, 

Guatemala 

Mr. Don Sarreals 

USA 

E-mail: dsarreals@aol.com 

Dr. Yoshihiro Sawada 

Hokkaido University 

Higashi-ku 

402-20-1,E20,N41 

Sapporo, 007-0841 

Japan 

E-mail: yy-sawada@happytown.ocn.ne.jp 

RADM James P. Schear 

Vice President for Safety 

FAA 

800 Independence Avenue 

Washington, DC 20591 

USA 

E-mail: james.schear@faa.gov 

Dr. Dave Schneider 

USGS-AVO 

4200 University Drive 

Anchorage, AK 99508 

USA 

Phone: 907-786-7037 

Fax: 907-786-7425 

E-mail: djschneider@usgs.gov 

Mr. Simona Scollo 

INGV-Catania 

piazza Roma 2 

Catania, 95123 

ITALY 

Phone: 957-165800 

Fax: 954-35801 

E-mail: scollo@ct.ingv.it 

Mr. Bradley Scott 

GNS 

Private Bag 2000 

Taupo, 

New Zealand 

Phone: 64-7-3748211 

E-mail: b.scott@gns.cri.nz 
The 2nd International Conference on Volcanic 

Ash and Aviation Safety 

Alexandria, Virginia 

June 21-24, 2004 

 B-20

Mr. Gianni Semenzato 

Senior Flight Inspector 

Italian Civil Aviation Authority 

Via de Villa Ricotti 42 

Rome, 

Italy 

Phone: 00390644185772 

E-mail: g.semenzato@enac.rupa.it 

Mr. Rene Servranckx 

Meteorological Service of Canada 

2121 North Service Road 

Transcanada Highway 

Dorval, QC H9P1J3 

Canada 

Phone: 514-421-4704 

Fax: 514-421-4627 

E-mail: rene.servranckx@ec.gc.ca 

Mr. Alan Shaffer 

Director, Plans and Programs 

Office of the Secretary of Defense 

3030 Defense 

Pentagon 

Washington, DC 20301 

USA 

Phone: 703-695-9604 

Fax: 703-695-4885 

E-mail: alan.shaffer@osd.mil 

Dr. Lynn Sherretz 

NOAA/FSL 

325 Broadway 

R/FS5 

Boulder, CO 80305 

USA 

Phone: 303-497-5580 

Fax: 303-497-6301 

E-mail: Lynn.Sherretz@noaa.gov 

Mr. Lee Siebert 

Smithsonian Institution 

NMNH, MRC-119 

Washington, DC 20013 

USA 

Phone: 202-786-2404 

E-mail: siebert@volcano.si.edu 

Mr. Herson H. Sierra 

Meteorologist 

Tegucigalpa MWO 

Colonia "Villa Centro Americana" Bloque "B" 

Casa 705 Tegueigalpa 

Honduras 

Phone: 504-253-8075 

Fax: 504-233-8075 

E-mail: hhsierras@latin.mail.com 

Mr. Matthew Simmons 

Tenix Investments Pty Ltd 

100 Arthur Street 

North Sydney NSW, 2060 

Australia 

Phone: +612 9963 9611 

Fax: -612 9963 9691 

E-mail: matthew.simmons@tenix.com 

Mr. Jim Skeen 

National Transportation Safety Board 

490 L'enfant Plaza East, SW 

Washington, DC 20594 

USA 

Phone: 202-314-6356 

Fax: 202-314-6404 

E-mail: skeenj@ntsb.gov 

Mr. George Stephens 

NOAA/NESDIS 

World Weather Building rm 510 

5200 Auth Rd. 

Camp Springs, MD 20910 

USA 

Phone: 301-763-8142 x129 

Fax: 301-899-9196 

E-mail: George.Stephens@noaa.gov 

Dr. Christopher Strager 

National Weather Service 

222 West 7th Avenue 

#23, Room 517 

Anchorage, AK 99513-7575 

USA 

Phone: 907-271-5132 

Fax: 907-271-3711 

E-mail: Christopher.Strager@noaa.gov 
The 2nd International Conference on Volcanic 

Ash and Aviation Safety 

Alexandria, Virginia 

June 21-24, 2004 

 B-21

Dr. Davida Streett 

NOAA 

5200 Auth Road 

Camp Springs, MD 20746 

USA 

Phone: 301-763-8444 

E-mail: davida.streett@noaa.gov 

Ms. Barbara Stunder 

Meteorologist 

NOAA Air Resources Laboratory 

1315 East West Highway (R/ARL) 

Silver Spring, MD 20910 

USA 

Phone: 301-713-0295 x114 

Fax: 301-713-0119 

E-mail: Barbara.Stunder@noaa.gov 

Ms. Grace Swanson 

Senior Meteorologist 

NOAA-NESDIS 

5200 Auth Rd. ,Room 401 

Camp Springs, MD 20746-4304 

USA 

Phone: 301-763-8444 

Fax: 301-763-8333 

E-mail: grace.swanson@noaa.gov 

Mr. Michael Szkil 

Meteorologist 

National Weather Service 

1325 East West Highway 

OS23/Room 13322 

Silver Spring, MD 20910-3283 

USA 

Phone: 301-713-1726, Ext. 144 

Fax: 301-713-1520 

E-mail: michael.szkil@noaa.gov 

Mr. Francisco Taitano 

Special Asst to the Governor 

Commonwealth of the Northern Mariana Islands 

PO BOX 2007 CK 

96950 Saipan 

Phone: 670-322-8001 

Fax: 670-322-7743 

E-mail: ftaitano@aol.com 

Dr. Hiroshi L. Tanaka 

Assoc. Professor 

University of Tsukuba 

1-1-1 Tenohdai 

Tsukuba, 

Japan 

Phone: 81-29-857-4502 

Fax: 81-29853-6879 

E-mail: tanaka@nakura.cc.tsukuba.ac.jp 

Mr. Steve Targosz 

Air Line Pilots Association, Int'l 

535 Herndon Parkway 

Herndon, VA 20170 

USA 

Phone: 703-689-4210 

Fax: 703-464-2104 

E-mail: russoa@alpa.org 

Mr. Hordur Thordarson 

Metservice 

PO Box 722 

30 Salamanca Road 

Wellington, 

New Zealand 

Phone: 00 64 04 470 0700 

Fax: 00 64 04 473 5231 

E-mail: thordarson@metservice.com 

Mr. Noriyuki Todo 

Japan Airlines International Co. Ltd. 

3-3-2 Haneda Airport , West Passenger Terminal 

Ota-ku 

Tokyo, 144-0041 

Japan 

Phone: -8814 

Fax: -9205 

E-mail: noriyuki.todo@jal.com 

Dr. Bennett Treadaway 

US Airways 

173 Industry Drive 

Pittsburgh, PA 15275 

USA 

Phone: 412-747-5176 

Fax: 412-747-3374 

E-mail: bgt@usairways.com 
The 2nd International Conference on Volcanic 

Ash and Aviation Safety 

Alexandria, Virginia 

June 21-24, 2004 

 B-22

Ms. Ahsha Tribble 

NOAA 

14th and Constitution Avenue, NW 

Washington, DC 

USA 

Phone: 202-482-5920 

E-mail: ahsha.tribble@noaa.gov 

Dr. Paul Try 

Sr. Vice President 

STC 

1010 Wayne Ave., Suite 450 

Silver Spring, MD 20910 

USA 

Phone: 301-565-8345 

Fax: 301-565-8279 

E-mail: ptry@stcnet.com 

Dr. Ted Tsui 

Naval Research Lab 

7 Grace Hopper Ave. 

Monterey, CA 93943-5502 

USA 

Phone: 831-656-4738 

Fax: 831-656-4769 

E-mail: tsui@nrlmry.navy.mil 

Mr. Andrew Tupper 

Bureau of Meteorology 

Met Bldg 

13 Scaturchio St 

Casuarina NT 812, 

Australia 

Phone: +61 8 8920 3867 

E-mail: a.tupper@bom.gov.au 

Mr. Louis Uccellini 

Director, NCEP 

NWS 

5200 Auth Rd, Room 101 

Camp Spring, MD 20746 

USA 

E-mail: louis.uccellini@noaa.gov 

Ms. Sarah Watkin 

Met Office 

FitzRoy Road 

Exeter, EX1 3PB 

United Kingdom 

Phone: +44 1392 886443 

E-mail: sarah.watkin@metoffice.com 

Dr. Matthew Watson 

MTU 

1400 Townsend Drive 

Houghton, MI 49931 

USA 

Phone: 906-487-2045 

Fax: 906-487-3371 

E-mail: watson@mut.edu 

Dr. Daniel J. Watt 

Aviation Meteorologist 

United Airlines 

PO BOX 66100 

Chicago, IL 60666 

USA 

Phone: 847-700-3093 

Fax: 847-7000-6054 

E-mail: dan.j.watt@ual.com 

Dr. Earle Williams 

Research Scientist 

Massachusetts Institute of Technology 

MIT 48-211 

Cambridge, MA 2139 

USA 

Phone: 781-981-3744 

Fax: 781-981-0632 

E-mail: earlew@ll.mit.edu 
The 2nd International Conference on Volcanic 

Ash and Aviation Safety 

Alexandria, Virginia 

June 21-24, 2004 

 B-23

Mr. Samuel P. Williamson 

Federal Coordinator for Meteorology 

U.S. Dept. of Commerce, NOAA 

Suite 1500 

8455 Colesville Road 

Silver Spring, MD 20910 

USA 

Phone: 301-427-2002 

Fax: 301-427-2007 

E-mail: Samuel.Williamson@noaa.gov 

Mr. David Woods 

NASA/GSFC 

Code 900 

Greenbelt, MD 20771 

USA 

Phone: 757-864-2672 

E-mail: david.woods@nasa.gov 

Mr. Bill Woolverton 

Environment Canada 

4999 98th Ave. 

Room 200 

Edmonton, AB T6B 2X3 

Canada 

Phone: 780-951-8830 

Fax: 780-951-8602 

E-mail: bill.woolverton@ec.gc.ca 

Dr. Jerry Wright 

Mgr. Security and Human Resources 

ALPA 

535 Herndon Pkwy 

Herndon, VA 20170 

USA 

Phone: 703-689-4197 

E-mail: jerry.wright@alpa.org 

Mr. Rick Wunderman 

Smithsonian Institution 

10th & Constitution Ave, NW 

MRC 119 

Washington, DC 20560-0119 

USA 

Phone: 202-357-1511 

Fax: 202-357-2476 

E-mail: rwunder@volcano.si.edu 

Dr. Jeff Wynn 

Team Chief Scientist 

U.S. Geological Survey 

1300 SE Cardinal Ct. 

Bldg 10 

Vancouver, WA 98683 

USA 

Phone: 360-993-8919 

E-mail: jwynn@usgs.gov 

Col. Neil Wyse 

USAF 

1401 Constitution Ave NW 

Rm 5807 

Washington, DC 20230 

USA 

Phone: (202)482-2355 

Fax: (202)482-4116 

E-mail: neil.wyse@noaa.gov 

Mr. Katsumi Yoshino 

All Nippon Airways Co., Ltd 

3-3-2 Haneda Airport 

Ota-ku 

Tokyo, 144-0041 

Japan 

Phone: 81-3-5757-5597 

Fax: 81-3-5757-3270 

E-mail: yoshinoka@ana.co.jp 

Mr. William Young 

Manager 

Tenix Investments Pty Ltd 

100 Arthur Street 

North Sydney NSW, 2060 

Australia 

Phone: +61 2 9963783 

Fax: 612 9963 9709 

E-mail: bill.young@tenix.com 
APPENDIX C 

PAPERS 
C-3 

INDEX OF PAPERS 

Session 1: Encounters, Damage, and Socioeconomic Consequences Session 1

1.1 2003 Caribbean Volcanic Ash Encounters 

Captain Albert M. Beerley, US Airways ALPA Training Committee, 

Philadelphia, PA, USA.......................................................................................................................... Page 1 

1.2 Engine Damage to a NASA DC-8-72 Airplane from a High-Altitude Encounter with a 

Diffuse Volcanic Ash Cloud 

Thomas J. Grindle, NASA, Edwards, CA, USA; and Frank W. Burcham, Jr. ..................................... Page 3

1.3 Aircraft Encounters from the 18th August 2000 Eruption at Miyakejima, Japan

Andrew Tupper, Bureau of Meteorology, Darwin, Australia; and Yasuhiro 

Kamada, Noriyuki Todo, Ed Miller ...................................................................................................... Page 5

1.4 Impacts of Volcanic Ash on Airline Operations 

Leonard J. Salinas, United Airlines Flight Dispatch, Chicago, Illinois, USA; and 

Daniel Watt ......................................................................................................................................... Page 11 

1.5 Air Niugini and the Volcanic Ash Threat 

Captain David Innes, Flight Safety Office, Air Nuigini, Papua, New Guinea .................................... Page 15 

1.6 Reducing Encounters of Aircraft with Volcanic Ash Clouds 

Marianne Guffanti, USGS, Reston, VA, USA; and Thomas J. Casadevall, Gari 

Mayberry............................................................................................................................................. Page 17 

P1.1 Aircraft Encounters with Volcanic Clouds over Micronesia, Oceania, 2002/2003 

Andrew Tupper, Bureau of Meteorology, Darwin, Australia; and Jason Davey,

Paul Stewart, Barbara Stunder, Rene Servranckx ............................................................................... Page 23

P1.2 Sulfurous Odors: A Signal of Entry into an Ash Plume – But Perhaps Less Reliable 

for Escape 

Richard Wunderman, Smithsonian Institution, Washington, DC, USA.............................................. Page 29

Session 2: The Volcanic Source - Eruption Monitoring and Reporting Session 2

2.1 A Global Perspective on Volcanoes and Eruptions 

Richard Wunderman, Smithsonian Institution, Washington, DC, USA; and Lee 

Siebert, James Luhr, Tom Simkin, Ed Venzke .................................................................................... Page 1 

2.2 Promise and Pitfalls in Eruption Forecasting 

Chris Newhall, USGS, Seattle, WA, USA............................................................................................ Page 3 

2.3 Status and Challenges of Volcano Monitoring Worldwide 

John W. Ewert, USGS, VDAP, Vancouver, WA, USA; and Christopher G. 

Newhall ................................................................................................................................................. Page 9 

2.4 Volcanic Alert Systems: An Overview of their Form and Function 

Bradley Scott, Institute of Geological and Nuclear Sciences, Wairakei, New 

Zealand................................................................................................................................................ Page 15 

2.5 Explosive Eruptions of Etna Volcano Seriously Threaten Aviation Safety in the 

Central Mediterranean Region 

Mauro Coltelli, INGV, Catania, Italy.................................................................................................. Page 17 

2.6 Recent Eruptive Activity in Ecuadorian Volcanoes and its Threat to Aviation Safety

Hugo Yepes A., Instituto Geofisico, Escuela Politecnica Nacional, QuitoECUADOR ........................................................................................................................................ Page 21 
C-4 

2.7 The Alaska Volcano Observatory – Fifteen Years of Working to Mitigate the Risk to 

Aviation from Volcanic Ash in the North Pacific 

Thomas L. Murray, USGS, AVO, Anchorage, AK, USA................................................................... Page 23

2.8 Ground-Based Real Time Monitoring of Eruption Clouds in the Western Pacific 

Kisei Kinoshita, Kagoshima University, Kagoshima, Japan; and Satoshi 

Tsuchida, Chikara Kanagaki, Andrew C. Tupper, Ernesto G. Corpuz, Eduardo P. 

Laguerta .............................................................................................................................................. Page 25 

P2.1 Acoustic Surveillance for Hazardous Eruptions (ASHE): A Proposal for a Proof of 

Concept Experiment 

Henry Bass, University of Mississippi; and Milton Garces, David McCormack, 

Peter Chen, Michel Jean...................................................................................................................... Page 31 

P2.2 Recurrence of Explosive Eruptions at Etna Volcano that Produce Hazard for 

Aviation 

Paola Del Carlo, INGV, Catania, Italy................................................................................................ Page 35

P2.3 A Proposed Alert-level Notification Scheme for Aviation and Ground-based 

Hazards at U.S. Volcanoes 

C.A. Gardner, USGS, Cascades Volcano Observatory, Vancouver, WA, USA; 

and M.C. Guffanti, C.C. Heliker, D.P. Hill, J.B. Lowenstern, T.L. Murray ....................................... Page 37

P2.4 Monitoring and Reporting of Kamchatkan Volcanic Eruptions 

Evgenii Gordeev, Institute of Volcanology and Seismology, PetropavlovskKamchatsky, Russia; and Sergei Senjukov, Olga Girina .................................................................... Page 43 

P2.5 Volcano-Related Information Available on the Internet: From Current Activity to 

the Past 10,000 Years 

Gari Mayberry, USGS, Washington, DC, USA; and Edward Venzke, James 

Luhr, Richard Wunderman, Lee Siebert, Marianne Guffanti.............................................................. Page 45

P2.6 Volcanic Tremor and its Use in Estimating Eruption Parameters 

Stephen R. McNutt, AVO, Fairbanks, AK, USA................................................................................ Page 49 

P2.7 Surprise/Sudden Onset Eruptions: The Case of Reventador Volcano – Ecuador, 03-

November, 2002 

Patricia Mothes, Instituto Geofisico, Quito-Ecuador; and Minard L. Hall, 

Patricia Ramon, Hugo Yepes .............................................................................................................. Page 51

P2.8 Ashfall Scenarios and Aviation Impacts of Future Eruptions of Cotopaxi Volcano – 

Ecuador 

Patricia Mothes, Instituto Geofisico, Quito-Ecuador; and Minard L. Hall, Pablo 

Samaniego, Hugo Yepes ..................................................................................................................... Page 53

P2.9 Airborne Ash Hazard Mitigation in the North Pacific: A Multi-Agency, 

International Collaboration 

Christina Neal, USGS, Anchorage, AG, USA; and AVO Staff, Olga Girina, Gail 

Ferguson, Jeffrey Osiensky................................................................................................................. Page 55

P2.10 Ground-Based Detection of Volcanic Ash and Suphur Dioxide 

Fred Prata, CSIRO Atmospheric Research, Aspendale, Australia; and Cirilo 

Bernardo.............................................................................................................................................. Page 57 

P2.11 The New Zealand Volcano Alert Level System – Its Performance in Recent 

Eruptive Activity 

Bradley Scott, Institute of Geological and Nuclear Sciences, Wairakei, New 

Zealand................................................................................................................................................ Page 59 

P2.12 Status of Monitoring Active Volcanoes of the Kurile Islands: Present and Future 

A.V. Rybin, Institute of Marine Geology and Geophysics, Yuzhno-Sakhalinsk, 

Russia; and Y.V. Karagusov, P.E. Izbekov, N.S. Terentyev, V.B. Guryanov .................................... Page 61 
C-5 

P2.13 Total Water Contents in Volcanic Eruption Clouds and Implications for 

Electrification and Lightning 

Earle R. Williams, Parsons Laboratory, MIT, Cambridge, MA, USA; and 

Stephen R. McNutt.............................................................................................................................. Page 67 

Session 3: Ash Cloud Observations, Modeling, and Forecasting Session 3

3.1 Modeling Volcanic Ash Transport and Dispersion: Expectations and Reality 

Rene Servranckx, CMC, MSC, Quebec, Canada; and Peter Chen........................................................ Page 1

3.2 Discrepancies Between Satellite Detection and Forecast Model Results of Ash Cloud 

Transport: Case Study of the 2001 Eruption of Mt. Cleveland Volcano, Alaska 

David J. Schneider, USGS, AVO, Anchorage, AK, USA; Rene Servranckx, Jeff 

Osiensky................................................................................................................................................ Page 7

3.3 Assessing Volcanic Ash Hazard by Using the CALPUFF System 

Sara Barsotti, Istituto Nazionale di Geofisica e Volcanologia, Pisa, Italy; and 

Augusto Neri, Joe Scire......................................................................................................................... Page 9

3.4 Potential of the ATHAM Model for Use in Air Traffic Safety 

Christiane Textor, Lab. Sciences du Climate et de L’Environnement, Paris, 

France; and Gerald Ernst..................................................................................................................... Page 15

3.5 Volcanic Ash and Aerosol Detection Versus Dust Detection Using GOES and 

MODIS Imagery 

Bernadette Connell, CIRA/CSU, Fort Collins, CO, USA................................................................... Page 21

3.6 Ice in Volcanic Clouds: Where and When? 

William I. Rose, Michigan Technological University, Houghton, MI, USA...................................... Page 27

3.7 First Measurements of Volcanic Sulphur Dioxide from the GOES Sounder: 

Implications for Improved Aviation Safety 

Fred Prata, CSIRO Atmospheric Research, Aspendale, Australia; and Anthony 

J. Schreiner, Gary P. Ellrod, Timothy J. Schmit ................................................................................. Page 35

3.8 Ground-Based Detection of Volcanic Ash and Sulphur Dioxide 

Fred Prata, CSIRO Atmospheric Research, Aspendale, Australia; and Cirilo 

Bernardo, Bill Young, Matthew Simmons.......................................................................................... Page 39 

P3.1 UW-Madison Advanced Satellite Aviation-weather Products MODIS/AVHRR/GLI 

Satellite Volcanic Ash Detection 

Steven Ackerman, Wayne F. Feltz, CIMSS/SSEC University of Wisconsin, 

Madison, WI, USA; and Tim Schmit, John Murray, David Johnson.................................................. Page 45

P3.2 Removal Processes of Volcanic Ash Particles from the Atmosphere 

Gregg Bluth, Michigan Technological University, Houghton, MI, USA; and Bill 

Rose, Matt Watson.............................................................................................................................. Page 51

P3.3 Sounding of Volcanic Clouds with Balloon-Borne Instruments: Improving 

Algorithms for Ash and SO2 in Remote Sensing Imagery 

John Chadwick, Idaho State University, Pocatello, ID, USA; and Zach Lifton, 

Ken Dean, Jim Chadwick.................................................................................................................... Page 55

P3.4 FALL3D: A Numerical Model for Volcanic Ash Dispersion in the Atmosphere 

A. Costa, Istituto Nazionale de Geofisica e Vulcanologia, Napoli, Italy; and G. 

Macedonio........................................................................................................................................... Page 57 

P3.5 Use of Dispersion Models to Track Eruption Clouds 

Ken G. Dean, Geophysical Institute, University of Alaska, Fairbanks, AK, USA; 

and Rorik A. Peterson, Ken Papp, Jonathan Dehn.............................................................................. Page 59 
C-6 

P3.6 Laboratory Measurements of Heterogeneous Ice Nucleation by Volcanic Ash:

Importance for Detecting and Modeling Volcanic Clouds 

Adam J. Durant, Michigan Technological University, Houghton, Michigan, 

USA; and Raymond A. Shaw, Youshi Mi, and William I. Rose......................................................... Page 61 

P3.7 Volcanic Ash Detection and Cloud Top Height Estimation from the GOES-12 

Imager: Coping Without a 12μm Infrared Band 

Gary P. Ellrod, NOAA/NESDIS, Camp Springs, MD, USA; and Anthony J. 

Schreiner, Alonzo M. Brown .............................................................................................................. Page 63

P3.8 Resuspension of Relic Volcanic Ash and Dust from Katmai: Still an Aviation 

Hazard 

David Hadley, NWS Alaska Aviation Weather Unit, Anchorage, AK, USA; and 

Gary L. Hufford, James J. Simpson .................................................................................................... Page 69

P3.9 Observing Popocatepetl’s Volcanic Ash Clouds Using MODIS Infrared Data 

M. Alexandra Matiella, Michigan Technological University, Houghton, MI, 

USA; and Hugo Delgado-Granados, William I. Rose, I. Matthew Watson ........................................ Page 71

P3.10 Comparison of Ash Detection Techniques Using TOMS, MODIS, AVHRR, and 

GMS: A Case Study of the August 18 and 28, 2000 Eruption Clouds of 

Miyakejima, Japan 

Emily McCarthy, Michigan Technological University, Houghton, MI, USA; and 

Gregg Bluth, Matthew Watson, Andrew Tupper, Yasuhiro Kamada.................................................. Page 73 

P3.11 Predicting Regions Susceptible to High Concentrations of Airborne Volcanic Ash 

in the North Pacific Region 

Kenneth Papp, Geophysical Institute, University of Alaska, Fairbanks, AK, 

USA; and Ken Dean, Jonathan Dehn .................................................................................................. Page 79

P3.12 Reanalysis of Eruption Clouds from the North Pacific and Their Impact on 

Aircraft Routes 

Rorik A. Peterson, Geophysical Institute, University of Alaska, Fairbanks, AK, 

USA; and Ken G. Dean, Ken Papp, Joanne Groves, Jonathan Dehn .................................................. Page 81

P3.13 Quantitative Sulphur Dioxide Retrievals from AIRS, MODIS and HIRS 

Fred Prata, CSIRO Atmospheric Research, Aspendale, Australia; and Cirilo 

Bernardo.............................................................................................................................................. Page 89

P3.14 Sakura – An Airborne Infrared Imaging Camera for the Detection Of Volcanic 

Ash and Sulphur Dioxide Gas 

Fred Prata, CSIRO Atmospheric Research, Aspendale, Australia ...................................................... Page 91

P3.15 Testing Real-Time Remote Sensing for Monitoring Volcanic Activity in Central 

America 

Armando Saballos, INETER, Managua, Nicaragua; and Peter Webley, Martin 

Wooster............................................................................................................................................... Page 93 

P3.16 Advances in Ultraviolet Detection of Volcanic Eruption Clouds 

Stephen J. Schaefer, Joint Center for Earth Systems Technology UMBC, 

Baltimore, MD, USA; and Arlin J. Krueger, Simon A. Carn.............................................................. Page 95

P3.17 Real-Time Monitoring of the Volcanic Ash Fallout Will Improve Airport Safety 

Simona Scollo, INGV, Catania, Italy; and Mauro Coltelli, Marco Folegani, 

Stefano Natali, Franco Prodi............................................................................................................... Page 97

P3.18 Development of Volcanic Ash Image Products Using MODIS Multi-spectral Data

George Stephens, OSDPD, NOAA/NESDIS, Camp Springs, MD, USA; and 

Gary P. Ellrod, Jun-Sun Im................................................................................................................. Page 99

P3.19 Volcanic Ash Dispersion Modeling Research at NOAA Air Resources Laboratory 

Barbara Stunder, NOAA/ARL, Silver Spring, MD, USA................................................................. Page 105
C-7 

P3.20 Operational Volcanic Ash Plume Prediction Model PUFF at the Japan Airlines 

H.L. Tanaka, Institute of Geoscience, University of Tsukuba and FRSGC, 

Japan; and Saburo Onodera, Daisuke Nohara ................................................................................... Page 111

P3.21 Detecting Ash Clouds in Tropical Atmospheres 

I.M. Watson, Michigan Technological University, Houghton, MI, USA; and 

W.I. Rose, G.J.S. Bluth ..................................................................................................................... Page 115

P3.22 Eruption Cloud Echo Measured with C-band Weather Radar 

Yoshihiro Sawada, Hokkaido University, Sapporo, Japan................................................................ Page 119

Session 4: VAAC Operations and Capabilities Session 4

4.1 The International Airways Volcano Watch (IAVW) 

Raul Romero, ICAO, Montreal, Canada ............................................................................................... Page 1

4.2 WMO Activities Related to Volcanic Ash

Saad Benarafa, World Meteorological Organization, Geneva, Switzerland ....................................... Page 11 

4.3 NOAA’s NWS Volcanic Ash Program: Current Status and Plans for the Future 

Christopher S. Strager, NWS Alaska Region Headquarters, Anchorage, AK, 

USA; and Jeffrey M. Osiensky, Gary L. Hufford ............................................................................... Page 13

4.4 Volcanic Ash Impact on International Airport of Mexico City (AICM), Due to 

Emissions of Popocatepetl Volcano 

Humberto Rodriguez, DMTA of SENEAM, Mexico, D.F. Mexico ................................................... Page 15

4.5 The Darwin VAAC Volcanic Ash Workstation 

Rodney Potts, Bureau of Meteorology Research Centre, Melbourne, Australia; 

and Mey Manickam, Andrew Tupper, Jason Davey ........................................................................... Page 19

4.6 Shared Situational Awareness and Collaboration Through the Use of the Volcanic 

Ash Collaboration Tool (VACT)

Jeffrey M. Osiensky, NWS Alaska Aviation Weather Unit, Anchorage, AK, 

USA; and Greg Pratt, David J. Schneider, Lynn Sherretz................................................................... Page 23 

4.7 Perspectives on Operational Volcanic Ash Warnings 

Hordur Thordarson, Meteorological Service of New Zealand, Wellington, New 

Zealand................................................................................................................................................ Page 25

4.8 Volcanic Cloud Conceptual Models for Volcanic Ash Advisory Centre Operations 

Andrew Tupper, Bureau of Meteorology, Darwin, Australia; and Gerald Ernst, 

Christiane Textor, Kisei Kinoshita, J. Scott Oswalt, Daniel Rosenfeld .............................................. Page 27

4.9 Volcanic Ash Advisory Support for the U.S. Department of Defense 

Charles Holliday, U.S. AFWA, Offutt AFB, Nebraska, USA ............................................................ Page 33

4.10 Web Access to the Volcanic Ash Advisory Database

Paula Dunbar, NOAA/NESDIS/NGDC, Boulder, CO, USA; and Grace Swanson ............................ Page 37 

P4.1 Washington Volcanic Ash Advisory Center (VAAC) Operations 

Gregory M. Gallina, NOAA SSD, Camp Springs, MD, USA; and Davida Streett............................. Page 43

P4.2 Improvement of Ash Cloud Information by Tokyo VAAC 

Takeshi Koizumi, Japan Meteorological Agency, Tokyo, Japan; and Yoshihiko 

Hasegawa, Yasuhiro Kamada, Masamichi Nakamura ........................................................................ Page 49

P4.3 The Montreal VAAC Toolbox: When Every Second Counts 

Mark McCrady, CMC, MSC, Quebec, Canada; and Serge Trudel, Jean-Philippe 

Gauthier, Rene Servranckx ................................................................................................................. Page 53
C-8 

P4.4 Eruption of Anatahan Volcano: Operations and Observations 

Michael G. Middlebrooke, NOAA/NWS, Barrigada, Guam .............................................................. Page 55

P4.5 The Volcanic Ash Collaboration Tool (VACT) 

Jeffrey M. Osiensky, NWS Alaska Aviation Weather Unit, Anchorage, AK, 

USA; and Greg Pratt, David J. Schneider, Lynn Sherretz................................................................... Page 63

P4.6 Volcanic Ash Monitoring and Forecasting at the London VAAC 

Sarah Watkin, Met Office, Exeter, Devon, U.K.; and Derrick Ryall, Helen 

Watkin, Helen Champion, Stewart Wortley, Nigel Gait ..................................................................... Page 65

P4.7 Web Access to the Digital Archive of VAA Messages and VAFTAD Model Output

Paula Dunbar, NOAA/NESDIS/NGDC, Boulder, CO, USA; and Grace Swanson ............................ Page 71 

Session 5: Aviation Industry Perspectives Session 5

5.1 Technology Transfer: Moving R&D to Operations

Steven R. Albersheim, Federal Aviation Administration, Washington, D.C., 

USA ...................................................................................................................................................... Page 1 

5.2 Effects of Volcanic Activity on Airports 

Marianne Guffanti, USGS, Reston, VA, USA; and Gari Mayberry, Rick 

Wunderman, Thomas J. Casadevall ...................................................................................................... Page 7

5.3 An Air Traffic Controller Perspective on Volcanic Ash: How to Deal with It 

Richard Hernandez, FAA San Juan Automated International Flight Service 

Station, San Juan, Puerto Rico, USA .................................................................................................. Page 11

5.4 The New Zealand Volcanic Ash Advisory System

Peter Lechner, Civil Aviation Authority of New Zealand, Wellington, NZ ....................................... Page 15 

5.5 Prevention of Volcanic Ash Encounters in the Proximity Area Between Active 

Volcanoes and Heavy Air Traffic Routes 

Saburo Onodera, Flight Crew Training Department, Japan Airlines, Tokyo, 

Japan ................................................................................................................................................... Page 21

5.6 A Program for Research and Systems Integration to Help Mitigate the Volcanic Ash 

Hazard to Aviation

Tenny A. Lindholm, National Center for Atmospheric Research (NCAR), 

Boulder, CO, USA .............................................................................................................................. Page 27 

5.7 Explosive Volcanic Eruptions Across the Heavily Traveled North Pacific Air 

Routes:Frequency, Duration, and Impact on Aviation 

Thomas P. Miller, USGS, AVO, Anchorage, AK, USA..................................................................... Page 31

P5.1 First 8 Hours of Volcanic Eruptions: A Northwest Airlines Example &

Recommendation of Revised Flow of Ash Information for Aviation

Tom Fahey, Northwest Airlines, Minneapolis/St. Paul, MN, USA .................................................... Page 33 
C-9 

INDEX OF AUTHORS 

 Paper# Page 

A 

Ackerman ..................P3.1 ........... Session 3 – Page 1 

Albersheim .................. 5.1 ........... Session 5 – Page 1 

B 

Barsotti ........................ 3.3 ........... Session 3 – Page 9 

Beerley ...................... 1.1* ........... Session 1 – Page 1 

Benarafa ...................... 4.2 ......... Session 4 – Page 11 

Bluth..........................P3.2 ......... Session 3 – Page 51 

C 

Chadwick................. P3.3* ......... Session 3 – Page 55 

Coltelli......................... 2.5 ......... Session 2 – Page 17 

Connell ........................ 3.5 ......... Session 3 – Page 21 

Costa........................ P3.4* ......... Session 3 – Page 57 

D 

Del Carlo ................. P2.2* ......... Session 2 – Page 35 

Dean ........................ P3.5* ......... Session 3 – Page 59 

Durant...................... P3.6* ......... Session 3 – Page 61 

Dunbar....................... 4.10 ......... Session 4 – Page 37 

................................. P4.7* ......... Session 4 – Page 71 

E 

Ellrod.........................P3.7 ......... Session 3 – Page 63 

Ewert ........................... 2.3 ........... Session 2 – Page 9 

F 

Fahey ....................... P5.1* ......... Session 5 – Page 33 

G 

Gallina .......................P4.1 ......... Session 4 – Page 43 

Gardner......................P2.3 ......... Session 2 – Page 37 

Gordeev ................... P2.4* ......... Session 2 – Page 43 

Grindle....................... 1.2* ........... Session 1 – Page 3 

Guffanti ....................... 1.6 ......... Session 1 – Page 17 

.................................... 5.2 ........... Session 5 – Page 7 

H 

Hadley ..................... P3.8* ......... Session 3 – Page 69 

Hernandez.................... 5.3 ......... Session 5 – Page 11 

Holliday....................... 4.9 ......... Session 4 – Page 33 

I 

Innes ............................ 1.5 ......... Session 1 – Page 15 

K 

Kinoshita ..................... 2.8 ......... Session 2 – Page 25 

Koizumi.....................P4.2 ......... Session 4 – Page 49 

_________________________ 

* Abstract only 

 Paper# Page 

L 

Lechner........................ 5.4 ......... Session 5 – Page 15 

Lindholm..................... 5.6 ......... Session 5 – Page 27 

M 

Matiella ................... P3.9* ......... Session 3 – Page 71 

Mayberry................... P2.5 ......... Session 2 – Page 45 

McCarthy ................ P3.10 ......... Session 3 – Page 73 

McCormack............... P2.1 ......... Session 2 – Page 31 

McCrady.................. P4.3* ......... Session 4 – Page 53 

McNutt ...................... P2.6 ......... Session 2 – Page 49 

Middlebrooke ............ P4.4 ......... Session 4 – Page 55 

Miller......................... 5.7* ......... Session 5 – Page 31 

Mothes..................... P2.7* ......... Session 2 – Page 51 

................................. P2.8* ......... Session 2 – Page 53 

Murray....................... 2.7* ......... Session 2 – Page 23 

N 

Newhall ....................... 2.2 ........... Session 2 – Page 3 

Neal ......................... P2.9* ......... Session 2 – Page 55 

O 

Onodera....................... 5.5 ......... Session 5 – Page 21 

Osiensky.................... 4.6* ......... Session 4 – Page 23 

................................ P4.5* ......... Session 4 – Page 63 

P 

Papp....................... P3.11* ......... Session 3 – Page 79 

Peterson................... P3.12 ......... Session 3 – Page 81 

Potts............................. 4.5 ......... Session 4 – Page 19 

Prata ...................... P2.10* ......... Session 2 – Page 57 

.................................... 3.7 ......... Session 3 – Page 35 

..................................... 3.8 ......... Session 3 – Page 39 

.............................. P3.13* ......... Session 3 – Page 89 

............................... P3.14* ......... Session 3 – Page 91 

R 

Rodriguez .................... 4.4 ......... Session 4 – Page 15 

Romero........................ 4.1 ........... Session 4 – Page 1 

Rose............................. 3.6 ......... Session 3 – Page 27 

Rybin....................... P2.12 ......... Session 2 – Page 61 

S 

Saballos ................. P3.15* ......... Session 3 – Page 93 

Salinas ......................... 1.4 ......... Session 1 – Page 11 

Sawada .................... P3.22 ....... Session 3 – Page 119 

Schaefer................. P3.16* ......... Session 3 – Page 95 

Schneider................... 3.2* ........... Session 3 – Page 7 
C-10 

 Paper# Page 

Scollo..................... P3.17* ......... Session 3 – Page 97 

Scott........................... 2.4* ......... Session 2 – Page 15 

.............................. P2.11* ......... Session 2 – Page 59 

Servranckx................... 3.1 ........... Session 3 – Page 1 

Stephens ..................P3.18 ......... Session 3 – Page 99 

Strager ....................... 4.3* ......... Session 4 – Page 13 

Stunder ....................P3.19 ....... Session 3 – Page 105 

T 

Tanaka .....................P3.20 ....... Session 3 – Page 111 

Textor .......................... 3.4 ......... Session 3 – Page 15 

Thordarson .................. 4.7 ......... Session 4 – Page 25 

Tupper ......................... 1.3 ........... Session 1 – Page 5 

...................................P1.1 ......... Session 1 – Page 23 

.................................... 4.8 ......... Session 4 – Page 27 

W 

Watkin .......................P4.6 ......... Session 4 – Page 65 

Watson.....................P3.21 ....... Session 3 – Page 115 

Williams ..................P2.13 ......... Session 2 – Page 67 

Wunderman ............. P1.2* ......... Session 1 – Page 29 

.................................. 2.1* ........... Session 2 – Page 1 

Y 

Yepes......................... 2.6* ......... Session 2 – Page 21 
1.1 

Session 1 – Page 1

2003 CARIBBEAN VOLCANIC ASH ENCOUNTERS 

Captain Albert M. Beerley, US Airways ALPA Training Committee, Philadelphia, PA USA 

On March 17, 2003, Flight Operations received information from the National Weather Service that the 

Montserrat volcano had erupted, spewing ash and particulate into the atmosphere. East to west upper and 

lower atmospheric wind patterns shifted north by northwest and volcanic ash was transported into 

populated areas. Dispatch immediately all contacted all aircraft enroute to San Juan, Puerto Rico, St. 

Thomas, St. Croix, St. Maarten, Antigua and Santo Domingo in an attempt to divert aircraft away from 

the adverse effects of this meteorological condition. Flight operations were terminated for almost six 

hours in San Juan and its surrounding area until a volcanic ash pilot report and Notice to Airmen was 

rescinded. On July 12, 2003 significant volcanic activity occurred once again at Montserrat. The dome of 

the volcano collapsed sending ash and particulate into the atmosphere. An Airbus aircraft inbound to San 

Juan, Puerto Rico encountered an unforeseen cloud of ash at approximately 6000 feet. The encounter 

subsequently caused damage to the aircraft’s engine fan blades and the forward flight deck windows. 

 
1.2 

Session 1 – Page 3 

ENGINE DAMAGE TO A NASA DC-8-72 AIRPLANE FROM A HIGH-ALTITUDE 

ENCOUNTER WITH A DIFFUSE VOLCANIC ASH CLOUD 

Thomas J. Grindle, NASA, Edwards, CA, USA 

Frank W. Burcham, Jr. NASA, Edwards, CA, USA 

The National Aeronautics and Space Administration (NASA) DC-8 airborne sciences research airplane 

inadvertently flew through a diffuse volcanic ash cloud of the Mt. Hekla volcano in February 2000 during 

a flight from Edwards Air Force Base (Edwards, California) to Kiruna, Sweden. Although the ash plume 

was not visible to the flight crew, sensitive research experiments and instruments detected it. In-flight 

performance checks and postflight visual inspections revealed no damage to the airplane or engine firststage fan blades; subsequent detailed examination of the engines revealed clogged turbine cooling air 

passages. The engines were removed and overhauled. This paper presents volcanic ash plume analysis, 

trajectory from satellites, analysis of ash particles collected in cabin air heat exchanger filters and 

removed from the engines, and data from onboard instruments and engine conditions. 
1.3 

Session 1 – Page 5 

AIRCRAFT ENCOUNTERS FROM THE 18 AUGUST 2000 ERUPTION AT MIYAKEJIMA, JAPAN 

Andrew Tupper1

, Yasuhiro Kamada2, Noriyuki Todo3, Ed Miller4

1 Bureau of Meteorology, Darwin, Northern Territory, 

Australia, and School of Mathematical Sciences, Monash 

University, Victoria, Australia

2 Japan Meteorological Agency, Tokyo Volcanic Ash 

Advisory Center, Tokyo, Japan

3 Japan Airlines International, Tokyo, Japan

4 Air Line Pilots Association, Herndon, Virginia, USA 

Corresponding author address: A.C. Tupper, Bureau of 

Meteorology Northern Territory Regional Office, PO Box 

40050, Casuarina NT 0811, Australia. E-mail: 

A.Tupper@bom.gov.au

Abstract

Four large commercial aircraft are known to have 

encountered clouds produced by the 16-17 km high 

phreato-magmatic eruption of 18 August 2000 at 

Miyakejima, Japan, which lies close to Japan’s two busiest 

airports at Haneda and Narita. Many other aircraft flew 

close by the eruption clouds. A near-new Boeing 737-800 

and a Boeing 747 both suffered extensive damage and 

required engine replacement. Another 747 encountered ash 

and sulphur dioxide, was inspected for three days without 

any damage found, and a third 747 encountered the cloud 

approximately 800 km (430 nautical miles) to the southeast, 

smelt sulphur dioxide but suffered no damage. Costs to the 

aviation industry are known to exceed US $12,000,000, but 

this figure is probably a gross under-estimate. The eruption 

was very well observed from the air and from the ground, 

and initial warnings were issued quickly, however 

SIGMETs did not give sufficient detail of the ash cloud 

dispersion, air-traffic management decisions appear to have 

been made on the basis of superseded VAAC forecasts for 

the prior, low-level eruption, and the known encounters all 

happened to foreign airlines, while Japanese airlines had 

access to more information about the activity at 

Miyakejima and made appropriate flight plans. The 

Miyakejima incidents teach us about the importance of preeruption information and planning, of having worldwide 

rather than country-specific ash-avoidance procedures, of 

universal and consistent information distribution, and of 

rigorous post-event investigations. On the positive side, the 

rapid eruption observation and reporting and the pre-flight 

planning of local airlines probably contributed to the lack 

of fatalities from this extremely dangerous eruption. 

Introduction

The phreato-magmatic eruption of Mount Oyama, 

Mikayejima, Japan, on 18 August 2000 was one of 

the most dangerous volcanic eruptions from the 

viewpoint of aviation safety in recent years. The 

eruption began on 8 July 2000 with a crater collapse. 

Several larger eruptions then occurred, on 10, 18t

 and 

29 August (Kinoshita et al., 2002). An evacuation 

order for Miyakejima residents was announced on 1 

September 2000, and high SO2 fluxes continue to 

affect the region. 

The eruption of 18 August was sudden, but not 

completely unexpected in the context of the 

preceding activity. Researchers from the Earthquake 

Research Institute of Tokyo University had already 

set up a camera to record the eruptions (Kinoshita et 

al., 2002), and since the volcano lies only 160 km 

south of Tokyo, public awareness was already very 

high. The event was well reported by pilots and 

ground observers, and seen remotely with hourly 

satellite imagery and radar (Iino et al., 2001: Tupper

et al., 2004). Despite this, two aircraft suffered 

severe damage from the eruption cloud 90 minutes 

after the beginning of the eruption, and two other 

aircraft are known to have flown through the cloud. 

Remote sensing issues associated with the eruption, 

and a brief chronology of events, are given in Tupper 

et al. (2004). The purpose of this paper is to focus on 

factors pertinent to the aircraft encounters. We are 

not seeking to apportion blame to individuals or 

agencies, but to examine issues associated with what 

is a complex and still developing warning 

International Airways Volcano Watch. 

Location of Encounters

The 18 August 2000 eruption occurred at 0802 UTC 

(17:02 JST) Fig. 1 shows the location of Miyakejima, 

and of the four verified encounters, the first two of 

which occurred at about sunset: 

i) A Boeing 747 had requested a diversion 

that was only partially allowed because of military 

airspace (“Octagon” on Fig. 1). The aircraft 

encountered ash cloud at 34,000 ft (10.3 km) at about 

0930 UTC, and exited the cloud at 30,000 ft (9.1 km) 

2 minutes later. The aircraft made an emergency 

landing at Narita. Three engines, the flight deck 

windshield, and some forward passenger windows 

were replaced. The fourth engine was to be replaced 

after 100 hours flying time. The airline made an 

initial cost estimate of at least US $5 million. 

ii) A near-new Boeing 737-800 also 

encountered the cloud at about 0930 UTC, at 36,000 

feet (10.9 km), having received no verbal warnings 

from Air Traffic Control or nearby aircraft. Just 

before penetration into the ash cloud, Air Traffic 

Control had given the flight a radar vector directing 

the aircraft 40NM (74 km) northeast of Airway B586, 

an action that was ineffective for avoidance. The 

flight management computer and electronic engine 
Session 1 – Page 6 

controls failed, but the engines still functioned. The 

cockpit filled with ‘haze and dust’. The aircraft made 

an emergency landing. Both engines were damaged 

and had to be replaced, forward visibility was lost on 

the windscreen except for a small area under the 

windshield wiper. The leading edges and tail were 

abraded, and the radome, air data probes damaged. 

The cost was at least US $ 5 million. 

iii) At 1235 UTC, a Boeing 747 

encountered strong sulphuric smells and ‘sparking’ 

on the windshield, strongly indicative of an ash 

encounter. The aircraft had diverted from Airway 

B586 to Airway 337 in an attempt to avoid the ash, 

and was partially successful since satellite imagery 

suggests less ash in that area. The aircraft was 

removed from service and inspected for three days, 

but no ash or damage was found. Nevertheless, the 

cost to this airline of diversions and inspections 

exceeded US $2 million. 

iv) At 2010 UTC, another 747 reported 

sulphuric smells. There was no evidence of ash in 

this encounter, although the aircraft was apparently 

not removed from service for a detailed inspection. 

This aircraft had diverted a considerable distance 

eastward from Airway 337, after receiving the report 

of the 1235 UTC encounter. 

Other aircraft movements

The movement of other aircraft around the eruption 

cloud are incompletely known. A DC-10 transited 

the same airspace at almost the same time as the first 

two confirmed encounters, but made no report. 

Given the extent of the eruption clouds and their 

proximity to Narita and Haneda airports, it seems 

likely that other aircraft encountered ash. 

Four Japan Airlines flights observed the eruption 

during the evening (from 0830 UTC to 0924 UTC), 

and successfully avoided the ash clouds, as did later 

night flights. It appears that the action taken was 

generally to fly to the northwest of the eruption, the 

only area unpolluted at cruising levels. This 

avoidance action appears quite contrary to the Air 

Traffic Control advice to the aircraft in encounter ii), 

and reflects the fact that the Japan Airlines flights 

were operating with superior information and were 

not reliant on the official warnings. 

Performance of International Airways Volcano 

Watch

Fig. 2 summarises the time and stated cloud height of 

advisories and warnings. The eruption was 

exceptionally well observed by the Japan 

Meteorological Agency and by pilots, reports were 

made extremely quickly, and the speed of issue of 

warnings was probably the fastest of any major event 

in the history of the International Airways Volcano 

Watch. The time from eruption, to the issue of a 

volcanic ash advisory, then to the domestic ‘Area 

Meteorological Advisory’ (ARMAD) and then the 

international SIGMET, the official meteorological 

warning for the eruption, was still twenty-three 

minutes in total, reflecting a long chain of 

communication. However, the first SIGMET was 

still issued over an hour before the two most serious 

aircraft encounters. 

Figure 1 - Detail of air routes around Miyakejima. 

Hexagons labelled i-iv denote positions of reported 

aircraft encounters. The areas of restricted 

airspace are labelled 'Octagon A' and 'Octagon B' 

A number of major problems can be identified. 

Firstly, the observation received by Tokyo VAAC at 

0812 UTC of an eruption with tops greater than

FL190 (5.8 km) was translated into tops to FL190 in 

the official NOTAM and SIGMETs (Fig 2, ‘a’). The 

entire avoidance procedure during the critical first 

phase of the eruption was based on the incorrect 

assumption of a low-level eruption. 
Session 1 – Page 7 

Figure 2 - Height of eruption reflected in observations, advisory and warning products. Lettered triangles 

show the time of key events described in the text, and hexagons show the time and height of confirmed 

aircraft encounters. 

Even though these warnings were superseded 

around 0835 UTC, the misinformation continued to 

propagate through the warning system, as the initial 

information was passed on. This kind of height 

confusion is actually quite common: a useful 

guideline may be to assume that eruption clouds 

above 5 km extend to the tropopause until evidence 

is given to the contrary (Tupper and Kinoshita, 

2003). 

Secondly, the cloud dispersion at cruising levels 

was not well understood. The Tokyo VAAC was 

unable to prepare and issue a full dispersion 

forecast for the eruption until 0925 UTC (‘b’ in 

Fig.2), i.e. about the time of the encounters. The 

SIGMETs, the official warning product, never 

included a dispersion forecast and stated only that 

the ash was going to the southeast or eastsoutheast. The wind field in the area and likely 

dispersion of the plume was well known, with an 

upper air observation station just to the south, and 

an observation of eruption height over 45,000 ft 

(13.7 km) and spot wind observation of northwest 

winds at 50 knots (92 km/h) reported to Air Traffic 

Control by JAL at 0830 UTC. Despite this 

controllers apparently failed to grasp the extent of 

the cloud and were directing aircraft into the ash an 

hour after the JAL report and high-level SIGMET. 

During the event, staff at Tokyo VAAC became 

concerned these issues, and took the initiative of 

distributing extra graphics showing a ‘close-up’ 

view of the eruption cloud. 

Figure 3 - Supplementary nephanalysis issued 

during the event by Tokyo VAAC. 
Session 1 – Page 8 

Thirdly, as in many other volcanic ash events, the 

procedures for warning cessation at the stage where 

ash becomes difficult to detect were not defined. 

Encounter iv) occurred after the high level ash had 

become impossible to detect on satellite imagery 

and as Tokyo VAAC staff were beginning to 

concentrate on the lower level eruption clouds (Fig. 

2, ‘c’). 

Fourthly, it appears that, where local operators such 

as Japan Airlines were in direct receipt of graphical 

warnings, followed their own contingency plans, 

and were well aware of the situation at 

Miyakejima, foreign operators were not as well 

informed. All operators should receive the official 

warnings, and an arrangement exists where Japan 

Airlines redistributes graphical advices to other 

airlines. However it is evident from the written 

reports of airlines that suffered damage that 

justifiably or otherwise, they felt badly informed. 

As a consequence, the Tokyo VAAC was pressured 

with phone calls from several airlines, as well as 

the media, frustrating the VAAC’s efforts to get 

information into the official warning system, and 

also frustrating the foreign operators who struggled 

with language issues. 

Finally, despite the seriousness of the encounters 

and some direct complaints by airline operators, we 

have been unable to find any evidence of an 

investigation by the government agencies 

concerned. We assume that, because no postanalysis is explicitly mandated in the arrangements 

of the International Airways Volcano Watch, and 

no agreement was in existence between the 

responsible agencies in Japan that required an 

investigation in a situation where aircraft have been 

damaged but no fatalities have occurred, no process 

existed to trigger such an investigation. 

Discussion

None of the issues identified above are uniquely 

Japanese. For example, in the Australian region, 

Qantas functions as a conduit for volcanic 

information to other international airlines in the 

same way that Japan Airlines does in Japan, and it 

is likely that any sudden eruption in Australian 

airspace would show that some airlines are far 

better informed than others. 

Formally, Volcanic Ash Advisory Centres exist to 

advise Meteorological Watch Offices about the 

dispersion of volcanic ash cloud. However, airline 

dispatchers, who make critical decisions about their 

aircraft, are often desperate for information during 

crises and will use whatever resources are available 

to make their decisions. Personal relationships are 

also highly emphasised in meteorological / aviation 

relationships the world over; information flows 

much more freely where offices perceive a good 

working relationship. 

A major challenge for the International Airways 

Volcano Watch is to ensure that enough 

information is distributed over official warning 

channels to allow all operators to avoid the ash 

cloud. Current initiatives, such as globally 

consistent volcanic ash graphics, universal 

SIGMET and NOTAM implementation, and better 

training, could substantially improve the 

information distribution. In turn, this will reduce 

the pressure on VAACs to provide telephone 

service to aviation operators. 

There are substantial issues of workload. For 

example, the SIGMET 2 for this event was: 

RJTG SIGMET 2 VALID 180845/181445 RJAA – 

TOLYO FIR VA MIYAKEJIMA (34.1N 139.5E) OBS 

at 0829 OVER MIYAKEJIMA VA TOPS MORE THAN 

FL400 DRIFTING TO E-SE BY B747 INTSF 

This SIGMET, while informative, contains no 

explicit dispersion forecast. In today’s coding, an 

appropriate SIGMET for that time may have been: 

RJTG SIGMET 2 VALID 180845/181445 RJAATOKYO FIR VA ERUPTION MIYAKEJIMA LOC N31 

E139 VA CLD OBS AT 0830Z SE OF MIYAKEJIMA 

SFC/FL460 N3415 E13925 - N3410 E13950 - N3345 

E13955 - N3350 E13930 - N3415 E13925 MOV SE 

40KT INTSF FCST 1445Z VA CLD APRX N3430 

E13915 - N3420 E14105 - N3035 E14330 - N3155 

E13850 - N3430 E13915 OTLK 012045Z VA CLD 

APRX N3435 E13905 - N3035 E13830 - N2855 E14505 

- N3415 E14220 - N3435 E13905 020130Z VA CLD 

APRX N3440 E13905 - N2955 E13830 - N2730 E14700 

- N3410 E14305 - N3440 E13905 

Even this SIGMET is a simplification, as it treats 

all the ash as one layer in a situation where the 

wind changed markedly with height. Text 

SIGMETs will be necessary for some time yet, 

until graphical products are universal. When 

composing and then decoding SIGMETs such as 

those above, which are derived from even more 

complex Volcanic Ash Advisories, some delay is 

inevitable unless the whole process can be 

simplified and/or automated. 

The deamnds of the media are unlikely to be 

reduced by informative warnings. It is difficult to 

keep operational contact numbers confidential, and 
Session 1 – Page 9 

every centre should have a firm policy for handling 

media enquiries during an event. Since there is 

virtually no public benefit in feeding extra 

information to the media during an event, 

responding these calls should be given a low 

priority at most. 

Large volcanic eruptions in any particular area are 

relatively infrequent. The mistakes made in the 

VAAC, Meteorological Watch Office, airline 

offices and Air Traffic Control centres are likely to 

recur for future eruptions in other regions unless 

regular training is performed. Similarly, the 

sensitivities associated with any damage from a 

volcanic event are such that, unless a clear protocol 

is already in place for post-analysis, it is possible 

that no effective investigation would be performed. 

A final point of interest is that no damage was 

found to the aircraft involved with encounter (iii), 

despite three days of inspections. When compared 

to the Hekla 2000 incident (Grindle and Burcham, 

2003), this suggests that further research is 

necessary to determine the danger threshold of ash 

clouds. 

Following the Miyakejima eruptions, the Tokyo 

VAAC has had substantial experience with other 

eruptions. Volcanic SIGMETs, previously 

restricted to heights around 5 km, are now issued 

for all altitudes. Numerous case studies have been 

conducted for training purposes, a VAAC web site 

has been created, and the Japan Meteorological 

Agency provides a representative to the ICAO 

International Airways Volcano Watch Operations 

Group, which is shaping the future warning system. 

Conclusions

The eruption of Miyakejima provides us with a 

remarkable example of a major eruption of a 

monitored volcano, in airspace serviced by highly 

sophisticated aviation and meteorological services. 

The eruption therefore gives us an insight into the 

issues that are likely to be prominent over the rest 

of the world once the basic technological 

challenges of monitoring are sorted out. 

In this case, despite rapid observation of the 

eruption and a relatively rapid issue of warnings, 

two aircraft were seriously damaged, and at least 

two others encountered the cloud. To address these 

challenges, we suggest: 

1) Further development of the International 

Airways Volcano Watch to ensure that 

information before and during an eruption 

is adequate for international aviation 

operators. 

2) Regular training and drills to ensure 

operational readiness. 

3) The development of internationally agreed 

post-analysis procedures for improvement 

of the International Airways Volcano 

Watch. 

Acknowledgements

We gratefully acknowledge the help of the airlines 

who anonymously provided information about their 

encounters with the Miyakejima eruption clouds, 

Dr. A. Terada of Hokkaido University for 

providing a video of the eruption, and Prof. K. 

Kinoshita of Kagoshima University for much 

related discussion and materials. We also 

acknowledge the operational efforts of the staff on 

duty during the eruption, which was the first major 

eruption in Japanese airspace since the creation of 

the Tokyo VAAC. 

References

Grindle, T. J. and F. W. Burcham, 2003, Engine damage 

to a NASA DC-8-72 airplane from a high-altitude 

encounter with a diffuse volcanic ash cloud. Technical 

Memorandum NASA/TM-2003-212030, 22 pp. 

Iino, N., K. Kinoshita, M. Koyamada, S. Saitoh, K. 

Maeno, and C. Kanagaki, 2001, Satellite imagery of ash 

clouds of the 2000 eruption of Miyake-jima volcano. 

CEReS International Symp. on Remote Sensing of the 

Atmosphere and Validation of Satellite Data, Chiba, 

Japan, 13-8. 

Kinoshita, K., C.Kanagaki, N.Iino, M.Koyamada, 

A.Terada, and A.Tupper, 2002, Volcanic plumes at 

Miyakejima observed from satellites and from the 

ground. Optical Remote Sensing of the Atmosphere and 

Clouds III, H.-L. Huang, D. Lu, and Y. Sasano, Eds., 

SPIE, 227-36. 

Tupper, A. and K. Kinoshita, 2003. Satellite, air and 

ground observations of volcanic clouds over islands of 

the Southwest Pacific. South Pacific Study, 23, 21-46. 

Tupper, A., S. Carn, J. Davey, Y. Kamada, R. Potts, F. 

Prata, and M. Tokuno, 2004. An evaluation of volcanic 

cloud detection techniques during recent significant 

eruptions in the western 'Ring of Fire'. Remote Sens. 

Environ., 91, 27-46, doi:10.1016/j.rse.2004.02.004. 
1.4 

Session 1 – Page 11 

VOLCANIC ASH CLOUDS 

POSE A REAL THREAT TO AIRCRAFT SAFETY

Leonard J. Salinas * 

United Airlines, Chicago, Illinois 

1. ABSTRACT 

 Volcanic ash clouds pose a real threat to aircraft 

safety. More than 100 jet aircraft have encountered volcanic 

ash clouds in the past 25 years often resulting in damage to the 

aircraft. The ash is abrasive and capable of causing serious 

damage to aircraft engines, control surfaces, windshields, and 

landing lights. The ash can clog the pitot-static systems, which 

determine airspeed and altitude, and can damage sensors that 

deliver electronic data to automated systems used to fly the 

aircraft. Seven of these encounters caused in-flight loss of jet 

engine power. 

 The ash cloud, transported by atmospheric winds, 

can drift over great distances causing disruption to air traffic 

and is a potential hazard to aircraft hundreds of miles from its 

source. 

 The hazard is compounded by the fact that volcanic 

ash clouds are not detectable by the present generation of 

radar instrumentation carried aboard aircraft. Complete 

avoidance of volcanic ash clouds is the only procedure that 

guarantees flight safety. 

 Addressing the threat of volcanic ash to aircraft 

safety has brought together Governments, University 

Scientists, Pilots, Dispatchers, Meteorologists, Air Traffic 

Controllers, and many representatives of the aviation industry 

to work collaboratively to reduce the hazards caused by 

volcanic ash. The First International Symposium and recently 

the Second International Conference on Volcanic Ash, 

Aviation Safety, The International Civil Aviation Organization, 

(I.C.A.O.), The World Meteorological Organization (W.M.O.), 

The Airline Pilots Association (A.L.P.A.), The Airline 

Dispatchers Federation (A.D.F.), and many others identified 

the need for specialized air carrier operations, procedures, 

communications, routings, and training are essential in 

maintaining a high level of flight safety. 

________________________________________ 

* Corresponding author address: 

Leonard J. Salinas, United Airlines, Program Manager 

Dispatch, Flight Safety and Operations-WHQFS 

P.O. Box 66100, Chicago, IL 60666; 

E-mail: leonard.salinas@united.com 

2. INTRODUCTION 

 The first notable encounter was the British Airways 

747 near Galunggung, Indonesia, in 1982. It showed that, in 

such encounters, we might expect a loss of engine power, 

problems with airspeed indications, and extensive abrasion 

damage, including a loss of windshield transparency. The 

encounter placed the flight in great danger, and it required 

heroic and persistent efforts by the crew to restart the engines 

and bring the flight to a safe conclusion (Tootell, 1985). 

 During the eruption of Redoubt Volcano in Alaska 

on 15 December 1989, a new B747-400 on a flight from 

Amsterdam to Anchorage flew into the plume and lost power 

from all four engines. The crew was able to restart the engines 

and land the aircraft safely. The initial estimate of damage to 

the aircraft was $80 million, including the replacement of all 

four engines (Brantley, 1990). 

3. WARNING-SYSTEM 

To ensure aviation safety, it is necessary that reports 

of eruptions be processed without delay into warnings to 

Pilots, Air Traffic Control Centers, and Air Carrier Operations 

Centers. Volcanoes are a threat to air safety from the moment 

that they erupt. A warning system should be capable of a 5-

minute response time once an eruption has been detected. The 

Mount St. Helens ash took approximately 5 minutes to reach 

aircraft-cruising altitudes (Rosenbaum and Waitt, 1981) at a 

rate of climb of approximately 5,000 ft per minute. A modern 

jet aircraft is traveling over 500 mph and advancing 6-8 miles 

per minute. 

 Winds play the dominant role in the distribution of 

volcanic ash. The agency for subsequent ash-location 

advisories should be the meteorological office. The 

computerized model of winds over the eruption site can be 

used, in conjunction with the dispersion models, to predict ash 

trajectories, as an aid to flight path planning for avoiding 

airborne volcanic ash, such as, the NOAA Air Resources 

Laboratory Volcanic Ash Forecast Transport And Dispersion 

(V.A.F.T.A.D.) model (Heffter and Stunder, 1998). 

4. VOLCANIC ASH ADVISORY CENTERS

 The Volcanic Ash Advisory Centers (V.A.A.C.s) 

were established in September 1995 in Darwin at a meeting of 

the I.C.A.O. At this meeting it was decided that in an effort 

to ensure that volcanic cloud hazards were addressed there 

must be an interface between Volcano Observatories, 

Meteorological agencies, Air Traffic Control Centers, and Air 

Carrier Operations. In order to meet their goal they decided 

the world should be divided into different regions 

differentiated by their volcanic activity and volcano 

observatories. The designated V.A.A.C. would be in charge 
Session 1 – Page 12 

of keeping track of the activity by analyzing satellite imagery 

in their designated region. 

 The V.A.A.C.s operate advanced science-based tools 

for detecting, identifying, tracking and projecting the 

movement of airborne volcanic ash. Because many of the 

world’s active volcanoes are located in uninhabited regions, 

the rapid detection and location of volcanic eruptions are often 

problematic (Chen, 1998). 

 The Volcanic Ash Advisory Statement (V.A.A.S.) is 

issued by the V.A.A.C.s. The V.A.A.C.s must provide the 

required advisory information to the various M.W.O.s for a 

timely issuance of the SIGMETS. 

 The nine V.A.A.C.s are the contacts meteorologists 

can utilize for many of the details regarding a volcanic 

eruption. They are Anchorage, Buenos Aires, Darwin, 

London, Montreal, Tokyo, Toulouse, Washington, and 

Wellington. 

 The I.C.A.O. International Airways Volcano Watch 

publication of Operational Procedures and List of Operational 

Contact Points Between Vulcanological Agencies, 

Meteorological Watch Offices and Area Control Centers 

provides areas of responsibilities on a global scale, the phone 

numbers, fax numbers, e-mail addresses, and electronic 

addresses. 

5. STATUS OF ACTIVITY OF VOLCANO 

 A color code for the “Level of Alert” indicates the 

status of activity of the volcano. A group representing many 

agencies, meeting in Anchorage, Alaska shortly after the 

Redoubt Eruption in 1989 developed this. It was determined 

this would be a simple method by which all could immediately 

understand the current condition of the volcano. 

RED Volcanic eruption in progress. 

 Ash plume/cloud reported above 

 FL250. 

ORANGE Volcanic eruption in progress but 

 ash plume/cloud not reaching 

 FL250. 

YELLOW Volcano known to be active from 

 time to time and volcanic activity 

 has recently increased 

 significantly, volcano not currently 

 considered dangerous but caution 

 should be exercised. 

GREEN Volcanic activity considered to 

 have ceased and volcano reverted 

 to its normal state. 

6. SIGMETS, NOTAMS, AND ASHTAMS 

 The operational requirements for the issuance of 

SIGMETS and NOTAMS have been part of the relevant 

Annexes for a number of years. The requirements for 

ASTAMS were included in Annex 15 - Aeronautical 

Information Services in November 1997. The SIGMET and 

NOTAM are excellent sources of information for the Pilot, 

Dispatcher, Air Traffic Control Facility, and Meteorologist. 

7. AIR CARRIER OPERATIONS 

Pilots are the last link in the chain of safety actions to 

avoid or mitigate encounters with volcanic ash. In order for 

pilots to be effective, it is necessary that the rest of the system 

meet the needs of the pilots. Pilots view the sky in terms of 

routes, fixes, and (or) coordinates. The Air Traffic Controller 

and Dispatcher are best equipped to provide this information to 

the Pilots in aviation language. 

 Approximately 600 of the 1,500 potentially active 

volcanoes are classified as active (Foreman, 1991). Volcanoes 

are not generally marked on aeronautical route charts. The 

Dispatcher or Air Traffic Controller will provide a statement of 

where an eruption is occurring expressed in aeronautical 

terminology, a bearing and distance from a navigational fix, or 

a latitude and longitude. Statements of distance will be 

expressed in nautical miles, rate of movement in knots, and 

plume heights in flight levels. References to time should 

always be in Universal Coordinated Time. 

 

8. PLUME AVOIDANCE 

 Before operating in a region of known potential 

volcanic activity Pilots and Dispatchers (Jointly Responsible 

for Flight Safety by Federal Air Regulations under 121) 

should check Significant Meteorological Information Reports 

(SIGMETs), Notices to Airmen (NOTAMs), ATC directives, 

and Pilot Reports (PIREPs) for that region. To aid in 

identifying regions that are potentially active at a particular 

time United Airlines has developed procedures that provide 

flight safety (Hinds and Salinas, 1998). Since volcanic 

eruptions can seriously impact operational routes and 

destinations the United Airlines Weather Center has been 

designated as the initial point of contact in the Operational 

Control Center (O.C.C.) to gather pertinent data and 

information and issue a United Airlines Volcano Advisory 

(UVA). The Meteorologists will research sources such as, but 

not limited to, VAAC’s, SIGMETS, NOTAMS, PIREPS, 

Volcano Observatories, ATC, VAFTAD’s, Local Station 

Managers, and Civil Emergency Agencies. The Air Carrier 

issues a text and graphic Alert noting the volcanic eruption. 

This advisory will appear on documents that are sent to the 

Pilots and Dispatchers. The United Volcano Advisory UVA 

will be updated continuously during the event and will only 

expire after no activity is evident and VAAC concurs. 

The advisory will contain the following: 

• Advisory Number 

• Valid Time (UTC) 

• Volcano Name and Location 

• Summit Height 

• Winds at Summit 

• Height of Eruption in Flight Levels 

• Winds at Flight Levels 

• Estimate Ash Coverage lat./long. 

• Comments (Plain Language) 
Session 1 – Page 13 

 This information will be provided in both text and 

graphical form that is much easier to use and are more 

compelling in terms of amending flight plans for the purpose 

of avoidance. The standard graphic product will utilize the 

internationally recognized symbol to represent a volcanic 

eruption in progress on the graphical display. 

9. MITIGATION FOLLOWING AN 

 INADVERTENT ENCOUNTER 

Emphasis must be placed on the avoidance of 

volcanic ash. Avoid flight at night in areas of known volcanic 

activity or in instrument meteorological conditions (IMC), 

when volcanic ash may not be visible. Plan the flight to remain 

well clear of reported activity. If possible, stay upwind of 

volcanic ash. But, if ash penetration occurs, crews should know 

what to do. Criteria for recognizing that one’s airplane is in a 

volcanic ash plume and suggested procedures for escaping 

from a plume, are covered in the paper Recommended FlightCrew Procedures if Volcanic Ash is Encountered (Campbell, 

1991). 

 

10. RECOGNITION 

 Volcanic ash may be difficult to detect at night or 

during flight through clouds; however, flight crews have 

observed the following conditions: 

• At night, heavy static discharges (St. Elmo’s fire) around 

the windshield, accompanied by a bright white glow in the 

engine inlets. 

• At night, landing lights cast sharp, distinct shadows 

in volcanic clouds (unlike the fuzzy, indistinct shadows 

that are cast against weather clouds). 

• Volcanic ash and dust appearing in the cockpit and 

cabin. 

• An acrid odor or the smell of sulfur. 

• Multiple engine malfunctions, such as surge, increasing 

exhaust-gas temperature, torching from tailpipe, and 

flameouts. 

• Decrease in indicated airspeed. 

11. ENCOUNTER PROCEDURES 

 If volcanic ash is encountered, accomplish the 

following (Campbell, 1991): 

• Immediately reduce thrust to idle. 

• Auto throttles off (if engaged). 

• Exit volcanic cloud as quickly as possible. Volcanic ash 

may extend for several hundred miles. The shortest 

distance/time out of the ash may require an immediate, 

descending 180-degree turn. 

• Engine and wing anti-ice on. All air conditioning packs 

on. Turn on engine and wing anti-ice. 

• Start the auxiliary power unit (APU), if available. 

• Oxygen mask on and 100 percent, if required. 

• Ignition on. 

• Monitor EGT. 

• Close outflow valves. 

• Do not pull fire switches. 

• Leave fuel boost pump switches “on” and open cross 

feed valves. 

• Do not use fuel heat. 

• Engine restart may be required. Successful engine start 

may not be possible until airspeed and altitude are within 

the air start envelope. 

• Monitor airspeed and pitch attitude. 

• Land at the nearest suitable airport. 

12. SPECIAL AIR REPORT OF 

 VOLCANIC ACTIVITY 

Pilot observations of volcanic activity are of use to others. The 

Volcanic Ash Working group has produced a special air report 

of Volcanic Activity Form (VAR), which is carried by United 

Airlines pilots and most other Air Carrier pilots. The form is a 

guide. The form should be delivered to the local 

meteorological office on arrival. This form provides a detailed 

and useful tool for others in accurate reporting. The ICAO 

standard for the contents include: 

• Aircraft identification 

• Position 

• Time 

• Flight level or altitude 

• Volcanic activity observed 

• Air temperature 

• Winds 

• Supplementary information 

13. CONCLUSIONS 

 There are 1,500 known volcanoes worldwide, and 

about 600 of these volcanoes are considered active. An 

average of 55-60 volcanoes erupt each year, and about 8-10 

of these eruptions produce ash clouds that reach flight 

altitudes. Volcanic Ash can reach aircraft cruise altitudes in 5 

minutes and considering jet aircraft are traveling at 5-8 miles 

per minutes a 5-minute communications warning system is 

imperative. 

 Pilot and Dispatcher training is a priority. Both 

must understand that volcanic ash is not like sand or dust, and 

they must know how to recognize inadvertent entry into an 

ash cloud. The Boeing Company in cooperation with the Air 

Line Pilots Association and the U.S. Geological Survey has 

developed a Volcanic Ash Training Video. In addition Pilots, 

Dispatchers, and Air Traffic Controllers must be aware of any 

potential volcanic activity affecting their area of operation. 

Should an inadvertent penetration of a volcanic ash cloud be 

made, flight crews must be aware of potential problems and 

be prepared to deal with the arising flight conditions. 

 Prompt communication among Volcano Observers, 

Meteorologists, Air Traffic Controllers, Flight Dispatchers, 

and Pilots regarding location of drifting ash clouds will 

maintain a high level of flight safety. 

 The detection and tracking of ash-cloud movement 

using remote-sensing techniques and atmospheric transport 

models continue to provide the graphical data required in 

long-range flight planning. Enhanced monitoring of the 
Session 1 – Page 14 

Earth’s active volcanoes, especially in the remote regions of 

the world, such as the new communication links with the 

Russians for warning and information about Kamchatkan 

volcanoes (Miller and Kirianov, 1993), now provides prompt 

notification of an eruption. 

 Location of a volcano has been simplified by using 

the Global Planning Chart showing the position of known 

active volcanoes relative to air routes and air navigation aids. 

(U.S.G.S. Casadevall and Thompson, 1994). 

 Avoidance requires the coordinated efforts of a 

broad group of technical specialists. The goal of these efforts 

is to avoid an area or airspace that has been contaminated by 

volcanic ash. Avoidance of Volcanic Ash Clouds is the only 

procedure that guarantees flight safety 

14. Acknowledgments 

The author would like to thank Ed Miller, ALPA 

Retired, Steven Albersheim, FAA, Marianne Guffanti, USGS, 

Samuel Williamson Office of Federal Coordinator of 

Meteorologists, Raul Romero, I.C.A.O, Nouhou Tata Diallo, 

World Meteorological Office, Barbara Stunder, NOAA-ARL, 

Christopher Strager, DOC/NOAA Alaska Region, Grace 

Swanson, NOAA-NESDIS, Tom Miller, Scientist Emeritus, 

USGS AVO, Christina Neal, USGS/AVO, Gary Hinds and 

Dan Watt, UAL Meteorologists, and Captain Hank 

Krakowski VP Flight Safety, Security and Quality Assurance, 

United Airlines, for their continued support, 

recommendations, and technical expertise, in the interest of 

Aviation Flight Safety in regard to the Hazards of Volcanic 

Ash. 

15. REFERENCES 

Brantley, S.R., ed., 1990, The Eruption of Redoubt Volcano, 

Alaska: U.S.G.S. C-1061, 33 p. 

Campbell, E.E., 1991, Recommended Flight-Crew Procedures 

If Volcanic Ash Is Encountered: 1st International 

Symposium, Bull.-2047, 151 p. 

Casadevall, T.J. & Thompson, T.B., 1994, Volcanoes and Air 

Navigation Aides-A Global Planning Chart: U.S.G.S.-Map 

GP-1011. 

Chen, P., 1998, Issues Facing The Volcanic Ash Advisory 

Centres: Workshop on Volcanic Ash, Toulouse, France. 

Foreman, P.M., 1991, Warning Systems And Pilot Actions: 

1st International Symposium, Bull.-2047, 163 p. 

Heffter, J.L. & Stunder, B.J., 1998, Modeling Volcanic Ash 

Transport and Dispersion: Workshop on Volcanic Ash, 

Toulouse, France. 

Miller, T.P., & Kirianov, V.Y., 1993, Notification Procedures 

For Kamchatkan Volcanic Eruption: U.S.G.S. Open -File 

Report 93-569, 9 p. 

Rosenbaum, J.G., & Waitt, R.B., Jrl, 1981, Summary O 

Eyewitness Accounts of The May 18 Eruption of Mount St. 

Helens, Washington: U.S.G.S. Professional Paper 1250, p. 

53-67. 

Tootell, E., 1985, All 4 Engines Have Failed; The True and 

Triumphant Story of Flight BA 009 and the Jakarta Incident: 

Auckland, Hutchinson Group Ltd., 178 p. 

 

 
1.5 

Session 1 – Page 15 

AIR NIUGINI AND THE VOLCANIC ASH THREAT 

Captain David Innes, Flight Safety Office 

Air Niugini, Papua New Guinea 

ABSTRACT 

Air Niugini is the national airline of Papua New Guinea, 

operating international services to Asia, Australia and the 

South West Pacific as well as domestic ports in the New 

Guinea Islands region. The airline operates a small fleet of 

turboprop and jet aircraft in an area notable for its high 

number of active volcanoes, some situated near major 

centre’s and airport's, many situated directly beneath major 

international air route's. Air Niugini's experience with 

volcanic activity and airborne ash has resulted in a heightened 

state of awareness of the phenomena and we have developed 

in house methods for maintaining crew awareness of the 

threat as well as standard operating procedures designed to 

better enable crews to manage ash encounters. Papua New 

Guinea's unusual reliance on air transport for commerce and 

communication mean's that the airline is continually seeking 

out those solutions best suited for our operating environment 

in order to maintain services in an area prone to volcanic 

activity. 

INTRODUCTION 

Papua New Guinea is an island chain stretching from 

Indonesia in the west to the Solomon Island's in the east, a 

distance of approximately nine hundred nautical miles. Most 

of the population lives on the main island but significant 

population centres exist on the outlying islands of New 

Britain, New Ireland, Manus and Bougainville. Air Niugini as 

the national carrier is tasked with servicing these 

communities as well as providing international connection's 

to neighbouring states. Many of the major population centres 

happen to be situated near active or dormant volcanoes, 

which are concentrated in a line reaching from the north coast 

of the main island across to New Britain and the island of 

Bougainville. 

 ENCOUNTERS 

Air Niugini crews fly in the vicinity of active volcanoes on a 

daily basis, but as yet we have been fortunate when it comes 

to actual ash encounters. The most significant encounters 

have involved Fokker F28 aircraft operating close to erupting 

volcanoes at Rabaul (Tavurvur) in 1994 and Manus Island in 

1996. In the first case, an F28 on the ground at Rabaul 

Airport was effectively scrambled in the midst of a volcanic 

eruption only a few kilometre’s from the airfield. In the 

second example, an aircraft enroute between the towns of 

Wewak and Madang reported passing close by Manus Island 

as it erupted. Other airborne encounters have been limited to 

observations only from a safe distance. Operational 

procedures from ash contaminated runways exist but given 

the lack of suitable ground equipment at many outport's for 

clearing ash and towing aircraft to clear areas for engine 

operations, company policy is to simply cease operation's to 

affected ports until the ash contamination has been cleared. 

Apart from Rabaul Airport, such ash deposits have been light 

coverings only. 

DAMAGE 

 Air Niugini has had no significant report of damage to its 

aircraft resulting from in flight ash encounters. Aircraft 

suspected to have flown in the vicinity of ash are removed 

from service while they are inspected and cleaned, and 

because of our restrictive operating procedure's, we find our 

aircraft serviceability and engine overhaul cycles are 

comparable to industry standards for our fleet type and type 

of operations. While our aircraft have fared well, the same 

cannot be said of some of the airstrips we operate into. 

Rabaul Airport was effectively destroyed by the 1994 

eruption, along with much of the town, and while Air Niugini 

was fortunate enough to manage to extract its aircraft during 

the eruption, several companies lost both fixed and rotary 

wing aircraft to heavy ash falls. 

 SOCIO-ECONOMIC CONSEQUENCES 

In regard to passenger services, the islands of New Guinea, 

New Britain, New Ireland and Bougainville are serviced 

almost exclusively by air. Sea transportation is relatively slow 

and infrequent and the country has no railway network. The 

mountainous terrain, up to 14000 feet or more in places, has 

limited road access to the coastal areas and one rough road 

into the Highlands region of the main island. Any major 

disruption to the countries regular air services has an 

immediate and severe impact on the communities involved, 

and it should be noted that apart from small numbers of 

commuter size aircraft, Air Niugini holds a virtual monopoly 

on regular public transport. Tourism is a major source of 

foreign income, as is small scale high value seafood and 

agricultural produce. The presence of volcanic ash near major 

centres invariably causes major disruptions to these industries 

with flow on effect's that run into weeks if not month's. When 

airstrips are closed due to volcanic activity, communities are 

reduced to travelling long distances to alternate airfields 

where the only service available is usually a small commuter 

aircraft of nine to nineteen seats capacity. 
Session 1 – Page 16 

Air Niugini's guidelines for operating in regions prone to 

volcanic activity are simple and effective, but result in 

frequent schedule delay's and cancelled flights. One example 

is the Rabaul area, where night operations are banned even 

though facilities exist for full night time operations. Aircraft 

do not overnight at this port due to the possibility of ash 

damage from the nearby volcano and flight in Instrument 

Meteorological Conditions (IMC) is not permitted. In the wet 

season, between November and April, flight's operating into 

Rabaul/Tokua frequently divert to Kavieng if there is cloud 

cover over Simpson harbour. If the flight is an early evening 

one, the designated alternate is Port Moresby, a seventy 

minute flight. Air Niugini and the communities it serve's are 

adversely affected by even the risk of volcanic ash due to the 

difficulty of establishing whether or not ash is actually 

present in area's of high risk. 

CONCLUSIONS 

Air Niugini has to date successfully managed to minimise the 

risk of exposure to volcanic ash through the use of a 

restrictive set of standard operating procedures. The negative 

consequence of this has been the disruption of services to 

communities almost wholly reliant on our scheduled services 

for commerce and communication's. We believe the best way 

of improving our schedule maintenance while maintaining 

our record for ash avoidance would be the adoption of 

volcanic ash detection technology suited to our particular 

needs. Ground based ash detection at certain airfields coupled 

with appropriate procedures would allow crews to make more 

informed decisions, thereby enabling the airline to better 

service the community while ensuring aircraft are protected 

from exposure to airborne ash. 
1.6 

Session 1 – Page 17 

REDUCING ENCOUNTERS OF AIRCRAFT WITH 

VOLCANIC-ASH CLOUDS

Marianne Guffanti, U.S. Geological Survey, Reston VA 20192, USA (guffanti@usgs.gov) 

Thomas J. Casadevall, U.S. Geological Survey, Denver CO 80225, USA 

Gari C. Mayberry, U.S. Geological Survey, Washington DC 20560, USA 

Introduction

 The volcanic-ash hazard to aviation is not a 

rare possibility on a worldwide scale, given that 

many major air routes traverse the world’s most 

volcanically active regions (Casadevall et al., 

1999; Ewert and Newhall, this volume). Miller 

and Casadevall (2000) estimate that volcanic ash 

can be expected to be in air routes at altitudes 

greater than 9 km (30,000 ft) for roughly 20 days 

per year worldwide. Numerous instances of 

aircraft flying into volcanic ash clouds have 

demonstrated the life-threatening and costly 

damages that can be sustained. Upon impact with 

aircraft traveling at speeds of several kilometers 

per minute, airborne ash particles abrade forwardfacing surfaces, including windscreens, fuselage 

surfaces, and compressor fan blades in turbine 

engines. Moreover, the melting temperature of the 

glassy silicate rock material that comprises ash is 

lower than the operating temperatures of modern 

jet turbine engines; consequently, ash particles 

ingested into such engines can melt in hot sections 

and then accumulate as re-solidified deposits in 

cooler parts of the engine. The overall result of an 

encounter of an aircraft with an ash cloud can be 

immediately degraded engine performance 

(including flame out and loss of thrust power), loss 

of visibility, and failure of critical navigational and 

operational instruments (Dunn and Wade, 1994). 

 Systematic collection of information about 

ash/aircraft encounters is important to substantiate 

the nature and extent of the risk to aviation and to 

improve the multi-faceted mitigation strategy of 

ash avoidance. To that end, the U. S. Geological 

Survey (USGS) and Smithsonian Institution, in 

collaboration with the Darwin Volcanic Ash 

Advisory Center, are compiling a summary of 

reported encounters in the form of a database that 

includes information about the source volcanoes 

that produced the ash clouds and conditions during 

the encounters. This paper presents a preliminary 

analysis of information about encounters from 

1973 through 2003. The bulk of the encounter 

data is published in the Manual on Volcanic Ash, 

Radioactive Material and Toxic Chemical Clouds 

by the International Civil Aviation Organization 

(ICAO, 2001). An updated summary of 

encounters will be provided to ICAO for 

publication in a future update of the 2001 Manual. 

Overview of Known Encounters

 Appendix I of the Manual on Volcanic Ash, 

Radioactive Material and Toxic Chemical Clouds 

(ICAO, 2001) identifies 83 ash/aircraft encounters 

from 1935 to 1993 and provides information about 

the source volcanoes, eruption dates, aircraft 

types, and severity of the encounters; preliminary 

mention of another ~17 encounters from 1994 to 

2000 is given in an accompanying table. An 

additional 9 encounters are known through 2003 

that are not included in the Manual. The most 

recent reported incident occurred in July 2003 in 

the Caribbean region (see Beerley, this volume). 

 From 1973 through 2003, 105 encounters of 

aircraft with airborne volcanic ash have been 

documented (Figure 1); this is a minimum value 

because encounter incidents are not consistently 

reported. The highest annual encounter rate (25 

incidents) occurred in 1991, mostly due to the 

eruption of Mt. Pinatubo in the Philippines. Since 

1991, 26 encounters are documented through 

2003, an average of two per year, again a 

minimum value. 

 The encounter database does not include 

information about aircraft caught on the ground at 

airports affected by ash; a separate database is 

being compiled for airport disruptions resulting 

from volcanic activity (see Guffanti et al., this 

volume). 

 Aircraft have been damaged by ash clouds 

from eruptions ranging from small, recurring 

episodes (e.g., at Soufriere Hills Volcano, 

Montserrat, 1996) to very large, singular events 

(e.g., at Pinatubo, 1991). Thirty source volcanoes 
Session 1 – Page 18 

have produced ash clouds encountered by aircraft 

(Table 1). (For a few encounters, the source 

volcanoes are not known.) Six volcanoes are 

associated with highest number of encounters 

(>5): Pinatubo in the Philippines, Sakura-jima in 

Japan, Galunggung in Indonesia, and St. Helens, 

Augustine, and Redoubt in the United States. 

 To quantify the effects of reported encounters 

on aircraft, a severity index for ash encounters 

(Table 2) has been formulated (ICAO, 2001). The 

criteria for each class in the severity index are 

based on the actual types of damage or conditions 

reported. Severity of encounters ranges from 

minor Class 0 incidents (acrid odor in cabin, 

electrostatic discharge on windshield) to very 

grave Class 4 and 5 incidents (engine failure). 

Fortunately, no Class 5 encounters (those resulting 

in crashes) have occurred. 

 In the database, most encounters (roughly 

75%) are Class 0-2. Accurately documenting the 

extent of Class 0 encounters is problematical. 

Some likely occur that not publicly reported 

because no significant damage is involved. 

Smelling sulfur does not necessarily indicate the 

presence of damaging ash, given that separation of 

the gas and ash components of volcanic clouds is 

known to occur (Bluth et al., 1994; Guffanti et al., 

in press). Moreover, the human nose very 

sensitive to sulfur dioxide (R. Wunderman, written 

communication, 2004) and may sense it at levels 

that are undetectable by remote-sensing methods. 

 A significant percentage (~25%) of encounters 

comprises serious Class 3-4 incidents. Eight Class 

4 encounters involving temporary engine failure 

occurred from 1980-1991 (Table 3). These 

encounters occurred 240 to 960 km (150 to 600 

miles) from the source volcanoes (St. Helens, 

Galunggung, Redoubt, Pinatubo, Unzen). The 

encounters lasted from 2 to 13 minutes at altitudes 

ranging between 4.6-11.3 km (15,000-37,000 ft) 

above sea level. 

 Some recent documented encounters in 

August 2000 did not involve engine failure, but 

were nevertheless very dangerous. A Boeing 737-

800 nearing Japan’s Narita Airport flew into an 

ash cloud produced during an eruption about an 

hour earlier at Mijake-jima volcano, located about 

100 miles from the airport. The engines continued 

to function, but the flight management computer 

and electronic engine controls failed. 

Handicapped further by severe loss of visibility 

due to abrasion of all but a small part of the 

windscreen, the crew managed a safe landing. 

Shortly thereafter, a 747 had a similar experience. 

Three additional aircraft also are thought to have 

encountered the Miyake-jima cloud. Costs to the 

aviation industry, including replacement of 

engines, exceeded US $12 million (see Tupper et 

al., this volume). 

 ICAO recommends that information on ash 

clouds and encounters be documented by having 

pilots complete the Volcanic Activity Report 

(VAR) when appropriate. The VAR can be found 

in Annex 3 and ICAO Doc 4444. Pilots and Air 

Traffic Services should complete these reports and 

forward them to appropriate services and agencies 

for operational use and historical record-keeping 

by the USGS and Smithsonian. In addition, 

encounter information can be sent to any of the 

authors of this paper or by email to 

gvn@volcano.si.edu. Such information does not

need to be received by the USGS and Smithsonian 

in an operational, real-time mode. Furthermore, 

information identifying the airlines or aircraft 

operators involved in encounters will not be 

included in the USGS/Smithsonian database. 

Discussion

 Under the auspices of ICAO’s International 

Airways Volcano Watch, operational procedures 

for ash avoidance have been formulated. 

Avoidance requires that dispatchers, pilots, and 

air-traffic controllers quickly learn of explosive 

eruptions and the locations of ash clouds. 

Accordingly, mitigation involves elements of: (a) 

real-time volcano monitoring and rapid eruption 

reporting, (b) detecting ash clouds in a timely 

manner, (c) forecasting expected cloud dispersion, 

(d) ensuring communication among the diverse 

parties responding to the hazard, and (e) not least, 

educating key operational personnel such as 

volcanologists, meteorologists, pilots, dispatchers, 

and air-traffic controllers about the hazard and 

how to respond to it (Guffanti and Miller, 2002). 

Arguably, implementation of these mitigation 

elements has reduced the likelihood of aircraft 

encounters with ash clouds. Fewer encounters 

have been reported since 1991 (Figure 1), while at 

the same time the amount of air traffic in volcanic 

regions grew (and the level of eruptive activity 

remained more-or-less constant). 
Session 1 – Page 19 

 But encounters do continue to occur for a 

variety of reasons. Unexpected eruptions occur at 

unmonitored volcanoes, and timely eruption 

reporting by volcanological agencies to the 

aviation sector sometimes is overlooked. Inherent 

limitations exist in remote-sensing methods of 

detecting ash clouds, including the time it takes to 

receive and analyze processed satellite data at 

ground facilities. Models for forecasting cloud 

dispersion also have significant limitations, such 

as incomplete input parameters describing the 

initial eruption plume and sparse wind-field data. 

Breakdowns occur in the multi-step process of 

information dissemination. Training and hazard 

awareness may be inadequate, especially as new 

personnel enter into critical positions. 

 Only as the above problems are identified and 

rectified can encounters be minimized or, ideally, 

eliminated altogether. Perversely, effective 

mitigation can give the erroneous perception that 

the hazard has been eliminated, leading to 

dangerous complacency. As our ability to prevent 

encounters improves to the point that even fewer 

incidents occur, we must not mistakenly conclude 

that no threat exists, but rather call for continued 

vigilance and support of proven, broad-based 

mitigation efforts. 

References Cited 

Beerley, A., this volume, 2003 Caribbean volcanic 

ash encounters. 

Bluth, G.J.S., Casadevall, T.J., Schnetzler, C.C., 

Doiron, S.D., Walter, L.S., Krueger, A.J., and 

Badruddin, M., 1994, Evaluation of sulfur 

dioxide emissions from explosive volcanism – 

the 1982-1983 eruptions of Galunggung, Java, 

Indonesia: Journal of Volcanology and 

Geothermal Research, v. 63, p. 243-256. 

Casadevall, Thomas J., Thompson, Theodore B., 

and Fox, Tom, 1999, World Map of 

Volcanoes and Principal Aeronautical 

Features: U.S. Geological Survey Map I-2700, 

scale 1:34,268,000, reprinted 2001. 

Dunn, Michael G., and Wade, Douglas P., 1994, 

Influence of volcanic ash clouds on gas 

turbine engines: U.S. Geological Survey 

Bulletin 2047, p. 107-118. 

Ewert, John W., and Newhall, Christopher, G., 

Status of volcano monitoring worldwide, this 

volume. 

Guffanti, Marianne, Casadevall, T.J., and 

Mayberry, G.C., this volume, Effects of 

volcanic activity on airports. 

Guffanti, Marianne, Ewert, J. W., Swanson, G., 

Gallina, G., and Bluth, G., in press, The 

volcanic-ash hazard to aviation during the 

eruptive activity in 2003-2004 of Anatahan 

Volcano, Commonwealth of the Northern 

Mariana Islands: Journal of Volcanology and 

Geothermal Research. 

Guffanti, Marianne, and Miller, E. K., 2002, 

Reducing the threat to aviation from airborne 

volcanic ash: Proceedings of the 55th Annual 

International Air Safety Seminar, Dublin, 

Nov. 4-7, 2002. Flight Safety Foundation, 

Alexandria, Virginia, p. 283-293. 

International Civil Aviation Organization, 2001, 

Manual on Volcanic Ash, Radioactive 

Material, and Toxic Chemical Clouds: ICAO 

Doc 9691-AN/954, Montreal, Canada. 

Miller, Thomas P., and Casadevall, Thomas J., 

2000, Volcanic Ash Hazards to Aviation: 

Encyclopedia of Volcanoes, Sigurdsson, H., 

editor, Academic Press, San Diego, California, 

USA, p. 915-930. 

Tupper, A., Kamada, Y., Todo, N., Miller, E., this 

volume, Aircraft encounters from the 18th

August 2000 eruption of Miyakejima, Japan. 
Session 1 – Page 20 

0

5

10

15

20

25

30

Year

Number of Encounters

Table 1. List of volcanoes that produced ash clouds encountered by aircraft, 1973-2003. Volcanoes 

are organized by country, eruption year in parentheses. 

____________________________________________________________________________________

Chile: Hudson (1991) 

Colombia: Nevado del Ruiz (1985) 

Dem. Rep. of Congo: Nyamuragira (1991) 

Ecuador: Guagua Pinchincha (1999), Tungurahua (1999) 

Guatemala: Fuego (1998), Pacaya (1987, 1993, 1998) 

Iceland: Hekla (2000) 

Indonesia: Colo (1983), Galunggung (1982), Langila (1997), Soputan (1985) 

Italy: Etna (1989, 2000) 

Japan: Asama (1973), Izu-Oshima (1986), Miyakejima (2000), Sakurajima (1975, 1977, 1978, 1979, 

1982, 1986, 1991, 1994), Unzen (1991), Usu (1997) 

Mexico: El Chichon (1982), Popocatepetl (1998) 

Philippines: Pinatubo (1991, 1993) 

Papua New Guinea: Manam (1993), Rabaul (1995) 

Russia: Kliuchevskoi (1994) 

United Kingdom: Soufriere Hills (1996, 2003) 

United States: Anatahan (2003), Augustine (1976, 1986), Redoubt (1989, 1990), St. Helens (1980) 

Figure 1. Frequency of reported encounters of aircraft with volcanic ash, 1973-2003. 

 75 80 85 90 95 00
Session 1 – Page 21 

 Table 2. Severity Index for Ash Encounters, from ICAO (2001, Appendix I, p. I-6). 

______________________________________________________________________________________ 

 Class Criteria

0 Acrid odor (e. g. sulfur gas) noted in cabin 

 Electrostatic discharge (St. Elmo's fire) on windshield, nose, engine cowls 

 No notable damage to exterior or interior 

______________________________________________________________________________________ 

1 Light dust in cabin; no oxygen used 

 Exhaust gas temperature (EGT) fluctuations with return to normal values 

______________________________________________________________________________________ 

2 Heavy cabin dust; "dark as night" in cabin 

 Contamination of air handling and air conditioning systems requiring use of oxygen 

 Some abrasion damage to exterior surface of aircraft, engine inlet, & compressor fan blades 

 Frosting or breaking of windows due to impact of ash 

 Minor plugging of pitot-static system; insufficient to affect instrument readings 

 Deposition of ash in engine 

______________________________________________________________________________________ 

3 Vibration of engines owing to mismatch; surging 

 Plugging of pitot-static system to give erroneous instrument readings 

 Contamination of engine oil hydraulic system fluids 

 Damage to electrical system 

 Engine damage 

______________________________________________________________________________________ 

4 Temporary engine failure requiring in-flight restart of engine 

______________________________________________________________________________________ 

5 Engine failure or other damage leading to crash 

Table 3. Summary of Class 4 encounters, modified from ICAO (2001) 

Encounter Date Source Volcano Encounter 

Altitude 

Encounter 

Duration 

25 May 1980 Mt. St.Helens, USA 15,000-16,000 ft ~4 minutes 

24 June 1982 Galunggung, Indonesia 37,000 ft 13 minutes 

24 June 1982 Galunggung, Indonesia 33,000-35,000 ft unknown 

13 July 1982 Galunggung, Indonesia 33,000 ft unknown 

15 December 1989 Redoubt, USA 25,000 ft ~8 minutes 

17 June 1991 Pinatubo, Philippines 37,000 ft 2 minutes 

17 June 1991 Pinatubo, Philippines unknown unknown 

27 June 1991 Unzen, Japan 37,000 ft unknown 
P1.1 

Session 1 – Page 23 

AIRCRAFT ENCOUNTERS WITH VOLCANIC CLOUDS OVER 

MICRONESIA, OCEANIA, 2002/03 

Andrew Tupper1, Jason Davey1, Paul Stewart2, Barbara Stunder3, Rene Servranckx4.

1 Northern Territory Regional Office, Bureau of 

Meteorology, Darwin, Northern Territory, Australia, and 

School of Mathematical Sciences, Monash University, 

Victoria, Australia

2 National Meteorological and Oceanographic Centre, 

Bureau of Meteorology, Melbourne, Victoria, Australia

3 NOAA Air Resources Laboratory, Silver Spring, 

Maryland, U.S.A.

4 Canadian Meteorological Centre, Meteorological Service 

of Canada, Montreal, Quebec, Canada 

Corresponding author address: A.C. Tupper, Bureau of 

Meteorology Northern Territory Regional Office, PO Box 

40050, Casuarina NT 0811, Australia. E-mail: 

A.Tupper@bom.gov.au

Abstract

Three aircraft encounters with volcanic clouds were 

reported over the Micronesia area, northeast of Papua New 

Guinea; two in November 2002 and one in March 2003. 

Satellite analysis was performed using standard techniques, 

but no detectable ash was found in the area. Back and 

forward trajectories were then performed, to attempt to 

identify the source of the volcanic clouds. For the March 

2003 encounter, the volcanic cloud most likely derived 

from Rabaul, Papua New Guinea, and was probably lofted 

from low altitudes to aircraft cruising levels during 

extensive convection in the area. The two aircraft in 

November 2002 appear to have encountered parts of a 

cloud approximately 350 km (190 nautical miles) across, 

and about 12 hours apart. One aircraft, an Airbus 340, 

reported intense St Elmo’s Fire, and light white ‘smoke’ 

with ‘burn smells’. Three pitot probes were replaced 

because of ash inside, some light abrasion was found on the 

engine air inlets but no damage on the windscreen or the 

nose, and no internal engine damage was reported. The 

second aircraft observed the ash cloud and smelt a slight 

odour but found no damage. In this case, the volcanic cloud 

almost certainly did not come from a local source, but was 

advected over a great distance. The most likely source of 

the cloud is the eruption of Reventador (Ecuador) twenty 

days earlier, but trajectory analysis is inconclusive. 

Introduction

It is important that every aircraft encounter with 

volcanic clouds be investigated, even when the 

damage is relatively minor, and the available 

information is incomplete. Here, we discuss three 

such encounters over or near Micronesia, north and 

northeast of Papua New Guinea. 

For these events, we produced forward and backward 

trajectories for the events described using the Hybrid 

Single-Particle Lagrangian Integrated Trajectory 

(HYSPLIT) model (Draxler and Hess, 1998), 

implemented at the Australian Bureau of 

Meteorology and at NOAA (Draxler and Rolph, 

2003), and the Canadian Meteorological Centre 

trajectory model (CMC, 2004), hereafter ‘CMC 

trajectory model’. We also conducted reverse 

absorption and visible analysis using GMS, GOES 

and MODIS data. 

Aircraft encounter on 8 March, 2003

On 8 March, 2003, at 1745 UTC an aircraft reported 

volcanic ash at FL330 (approximately 10 km altitude) 

to the Oakland, U.S.A., air traffic control centre. The 

position was given as within 60 nautical miles (111 

km) of the equator at 156E, at the border of the Port 

Moresby (Papua New Guinea) and Oakland Oceanic 

Flight Information Regions. The information was 

passed on by telephone to the Guam Weather 

Forecast Office, which then issued a SIGMET for 

volcanic ash cloud. 

The report was passed to Washington Volcanic Ash 

Advisory Centre (VAAC), who immediately 

contacted the Darwin VAAC, as the report originated 

within Darwin’s area of responsibility (ICAO, 2004). 

Washington and Darwin meteorologists discussed the 

satellite analyses (no ash detected, no known major 

eruption, no obscuring factors such as cloud in the 

area), and both VAACs issued advisories to alert 

Meteorological Watch Offices in the area to the 

situation. The SIGMET issued from Guam was not 

found in Darwin VAAC communications traffic, 

indicating either an addressing problem or a problem 

in the message handling within the Australian Bureau 

of Meteorology. 

No hard copy of the report was received in Guam, nor 

was any further information logged at Oakland 

(Frank Wells (NOAA), Steven Albersheim (US 

FAA), personal communications). Enquiries to 

various airlines have also proved fruitless; 

accordingly, we have no knowledge of damage 

caused or of any characteristics of the ash encounter, 

which is somewhat frustrating. Our analysis here is 

based on the assumption that the information received 

was correct, if sketchy. 
Session 1 – Page 24 

Under this assumption, we surmise that the encounter 

did not cause severe on-board systems failure (from 

the lack of media reports), and that, as the encounter 

occurred on a moonless night, that visible or other 

sensible indications of volcanic ash were close to the 

aircraft in order to be observed by the crew. 

Figure 1-CMC backward trajectories for 8 March 

2003 encounter, for endpoints at 9, 10 & 11 km at 

18 UTC on 8 March 2003, beginning 4 March 00 

UTC. Volcanoes with known or assumed activity 

during the period are indicated, and the star 

indicates the encounter location. 

Figure 2 - 27-member ensemble HYSPLIT backtrajectories for 8 March 2003 encounter using 

(left) Bureau of Meteorology TLAPS analyses, and 

(right) NOAA FNL data. End-point separation 1 

grid-point (horizontally), 0.01 grid point 

(vertically). 

Figs. 1 & 2 show CMC trajectory model and 

HYSPLIT back-trajectories from the location of the 

encounter. Of the active volcanoes indicated in Fig. 1, 

explosive eruptions were most likely from Rabaul, 

Ulawun, Langila, Ambrym, and Lopevi. However, 

the only explosive activity actually observed (most of 

these volcanoes are not constantly monitored) was 

from Tavurvur cone at Rabaul, which fluctuated 

between ‘white vapour’ and ‘convoluted pale grey 

ash clouds’ rising a few hundred metres above the 

223 m summit (Rabaul Volcano Observatory, 2003). 

This height is well below aircraft cruising levels, but 

the vertical motion shown in both figures suggests of 

the possibility of ash rising in convection or synoptic 

scale ascent. 

The differences in the ensemble trajectories, and the 

differences between these trajectories and the CMC 

trajectory model, reflect the input analyses. In this 

case, TLAPS has probably captured the low-mid 

level monsoon trough slightly better because of the 

higher resolution. These ensemble trajectories 

suggest a more westward source than the CMC 

output, with many of the TLAPS ensemble members 

showing a source south of Papua New Guinea. This 

area is, however, not volcanically active: the most 

likely candidate volcanoes are in the New Britain 

region of Papua New Guinea, where the three models 

have all indicated a possible source region. 

Satellite imagery at 1745 UTC on 6 March (not 

shown), indicates a deep layer cloud mass with 

embedded convection near Rabaul, associated with 

the convergence north of a strong monsoon trough 

and Coral Sea low near 15oS (Darwin Regional 

Specialised Meteorological Centre, 2003). The cloud 

mass moved over a wide area, with cumulonimbus 

tops advecting slowly towards the northeast (and 

toward the position of the aircraft encounter) and 

dissipating. The situation two days later, at the time 

of the aircraft encounter, had another period of deep 

cloudiness beginning near New Britain, while skies 

near the encounter were relatively clear of cloud. This 

satellite analysis supports the strong vertical motion 

indicated by the model analyses. 

The location of the suspected encounter is consistent 

with ash from eruptions at Rabaul, New Britain, 

several days earlier, transported in the vertical by 

enhanced ascent associated with an active monsoonal 

cloud mass. We presume that the concentration of 

ash at this time would have been quite low, given the 

effects of over 3 days of dispersion, enhanced for a 

period of at least 12-24 hours by moisture deposition 

and fallout within the precipitating cloud mass. 
Session 1 – Page 25 

Aircraft encounters, 23/24 November, 2002

Fig.3 shows the locations of the two encounters 

discussed here. Three pilot reports were received, 

shown here with our comments in italics. 

Encounter 1: 

1. IDENTIFIER - (removed for confidentiality)

2. POSITION - 80NM NORTH W/P DOHRT-AWY B452 

(DOHRT is at 0N, 156.83E)

3. TIME - 23.1728Z 

4. FLT LEVEL - FL330 (about 10 km)

5. VOLC ACTIVITY OBSERVED AT - NOT 

REPORTED 

6. AIR TEMP - M35C 

7. SPOT WIND - 150/10 

SUPP INFO - VOLCANIC ASH REPORTED AS 

FLYING IN CB (cumulonimbus) CLOUD 

ACI RQST ANY REPORTS THAT U MAY HAVE 

RCVD. 

In post-flight briefing, the aircraft crew reported 

intense St Elmo’s Fire, and light white ‘smoke’ with 

‘burn smells’. These symptoms are characteristic of 

moderate severity ash encounters. The report was not 

transmitted during the flight because the crew were 

unable to establish contact with either Port Moresby 

or Oakland; radio interference is another 

characteristic of volcanic ash encounters. The 

aircraft, an Airbus 340, had three Pitot probes 

replaced because of ash inside, some light abrasion 

on the engine air inlets but no damage on the 

windscreen or the nose. The encounter lasted about 

one minute at cruising speed (≈900 km/h), suggesting 

an area of distinct ash cloud of the order of 15 km 

wide. 

Eight hours later, a report was received from an 

aircraft on the ground at Rabaul: 

LOCAL DATE - 24NOV2002 

TIME (UTC) - 240330Z 

A/C POSITION - ON THE GROUND TOKUA (AYTK) 

(Tokua airport)

A/C - P2-ANI 

FLT NO. - PX204 

VOLCANO NAME – TAVURVUR (note: a cone at 

Rabaul)

DIRECTION OF ASH DRIFT - VERY HEAVY ASH 

FRM VOLCANO GOING STRAIGHT INTO CLOUD 

(BASE 3000FT) (about 900 metres)

WIND - LIGHT NORTH WESTERLY

Four hours after this, a second encounter report was 

made: 

Encounter 2: 

1. IDENTIFIER - (removed for confidentiality)

2. POSITION - 0320N 15210E 

3. TIME - 24.0717Z 

4. FLT LEVEL - FL360 (about 11 km)

5. VOLC ACTIVITY OBSERVED AT - NOT 

REPORTED 

6. AIR TEMP - NOT REPORTED 

7. SPOT WIND - NOT REPORTED 

8. SUPP INFO - PLAIN LANGUAGE QUOTE NOT 

CONCLUSIVE BUT POSS SLIGHT HAZE AND A 

LITTLE SMELL AT FL360 UNQUOTE 

Additional information was also obtained from this 

airline: ‘The pilot in charge of that flight 

acknowledges that the signs were inconclusive and 

not agreed by all flight crew. The time and location 

were his recollection of actual event. He added that 

looking down-sun the haze was evident, and looking 

up-sun there was a “corona” around the sun. They 

flew into clearer air without these signs a bit later.’ 

Further inquiries elaborated on the phrase ‘a bit 

later’: ‘they could discern a different “haze” below 

them for about 20 minutes before the sulphurous 

smell was noticed. That lasted for “2-3 minutes, less 

than 5 anyway”’. These additional data emphasise 

the importance of obtaining complete information at 

the time of a report. At cruising speed, a cloud 

observed for 20-25 minutes corresponds to an 

approximate cloud width of 300 – 375 km, with the 

area where the smell of sulphur was noticed about 30-

45 km across. 

Figure 3 - 20-day back trajectories for Encounter 

1 in November 2002, using HYSPLIT/GASP, 

ending 00 UTC 24 November 2002 (top), and for 

Encounter 2, ending 12 UTC (bottom). The 

positions of encounters 1 & 2 on 23/24 November 

are marked with stars. 
Session 1 – Page 26 

Analysis of GMS-5/VISSR, EOS/MODIS and 

NOAA/AVHRR data (not shown) did not indicate 

any ash in the area. Back trajectories (Fig.3) show 

that the cloud at the position of Encounter 2 was near 

approximately 2N 157E at the time of Encounter 1 

(that is, within 50 km of Encounter 1), and at altitude 

of 10 km. It is therefore highly likely that the aircraft 

encountered parts of the same cloud. Because 

Encounter 1 occurred during the night, any haze or 

corona (suggesting ash or sulphate aerosols) would 

probably not be observed, and the cloud was probably 

only noticed when a less diffuse area affected the 

aircraft for a short period. At the time of Encounter 

2, the sun was low in the sky (4 degrees elevation), 

which would make the haze more visible. Had the 

flight been slightly later, it is possible that no report 

would have been made at all, since the smell of 

sulphur was not a mandatory reporting element for 

aircraft (this is expected to change in the near future). 

One possible source of this ash cloud was, the 

entrainment of volcanic ash into deep convection. 

The report from Tokua airport gives a strong 

indication of this phenomenon. However, this event 

occurred after the first encounter, and some distance 

away. Moreover, satellite, manual and model 

analysis prior to the encounters (not shown) all had 

light and variable winds at the surface and strong 

easterlies in the upper levels, suggesting that 

advection of ash from Rabaul to the encounter 

location was virtually impossible. The active 

volcanoes in the vicinity of the encounters were the 

same as those shown in Figure 1, but short-term 

back-trajectories (not shown) indicate little chance of 

ash from these volcanoes being responsible for the 

encounters. 

If the ash did not derive from a local source, then it 

must have originated in a major eruption some 

distance away. This would be consistent with the 

sizeable width of the diffuse cloud. Encounters with 

ash at a great distance from the source have occurred 

before (Casadevall, 1994). Fig. 3 shows an extended 

20-day backward trajectory from the position of 

Encounter 1, using HYSPLIT-4 with GASP analysis 

data. This and other back-trajectories performed (not 

shown) initially came from the east, giving a high 

degree of confidence to the diagnosis of a remote 

eruption source. At a greater distance from the 

encounters, there is significant divergence in both 

position and altitude. Many trajectories meander 

along the equator, while others go near Hawaii, North 

America, and Japan. One CMC back-trajectory (not 

shown) reached as far as Italy, where Mt Etna was in 

eruption with ash being emitted at low levels. 

However, by far the biggest eruption globally in 

November 2002 was the eruption of El Reventador, 

in Ecuador, South America, on 3-5 November. The 

eruption column was at least 17 km high, with 

approximately 53 kilo-tonnes of sulphur dioxide 

released, and an unknown quantity of ash 

(Smithsonian Institution, 2004). El Reventador is 

almost exactly east of the encounters (albeit 13950 

km east!). Since the tropospheric portion of the 

eruption cloud was observed to drift westwards in 

equatorial easterlies, and the clouds associated with 

the encounters twenty days later came from the east, 

El Reventator is a potential source of the ash clouds. 

Twenty-day forward trajectories from the last 

observed position of the Reventador ash were 

performed to further investigate the possibility of 

Reventador being the source of ash for the 

Micronesia encounters. Fig. 4 shows the CMC 

trajectory result for this case; the ash initially heads 

westwards for several to many days, reaching as far 

eastwards as 160W, then tracks southwards in the 

Southern Hemisphere. HYSPLIT trajectories also 

show a number of possible tracks, including into the 

Northern Hemisphere. In general the speed of 

movement of the ash is a little too slow to reach 

Papua New Guinea in twenty days, although of 

course this is very sensitive to altitude in the models. 

Therefore, although the circumstances remain 

suggestive, we are not able to definitively verify 

Reventador as the source using either satellite 

techniques or trajectory forecasts. On the other hand, 

we are unable to suggest any other likely sources. 

Figure 4 - 20-day CMC forward trajectories from 

the last known position of the Reventador 

eruption cloud, 5 November 2002. 

Discussion

These cases show some of the more frustrating 

aspects of operational monitoring, detection and 

forecasting of volcanic ash for aviation: 
Session 1 – Page 27 

- Pilot reporting is intermittent, sometimes not in realtime, and is often haphazard. The information 

obtained for November 2002 was remarkably good 

and reflects on the efficient operation of the airlines 

involved; on the other hand, the pilot report from 

March 2003 was vague and impossible to clarify. 

- Volcanic eruption information in areas like the 

South Pacific is often difficult to obtain, due to 

resource and communication difficulties (Tupper and 

Kinoshita, 2003). Our analysis assumptions here 

have rested partly on the lack of major eruption 

reports from Bougainville, the Solomon Islands, and 

Vanuatu, all of which have inadequate volcanic 

monitoring. 

- Satellite analysis was unable to identify volcanic 

clouds at the time of the encounters. This is not a new 

issue; satellite-based monitoring in the tropics is 

frequently problematic (Tupper et al., 2004), 

increasing our reliance on ground-based reporting. 

- For the March 2003 encounter, comparisons 

between trajectories based on different 

meteorological datasets show some significant 

divergence after 1-2 days. The trajectories suggest 

differences in the analyses of the three-dimensional 

wind field (e.g. strengths and/or positions of the 

monsoon trough, Coral Sea low, etc) and are an 

example of the increased uncertainty of trajectories in 

complex meteorological situations. 

Conclusions

The volcanic ash from a reported aircraft encounter in 

March 2003, if reported correctly, most likely came 

from low level eruptions at Tavurvur, Rabaul, Papua 

New Guinea, after being advected to high levels 

during an active monsoon. In November 2002, an 

aircraft was significantly damaged by ash from an 

unknown source, and another aircraft flew through a 

part of the same cloud twelve hours later. The source 

of this cloud almost certainly was not local, and 

therefore originated from a major eruption elsewhere 

in the world. The most likely candidate source of the 

ash was El Reventador in Ecuador, but we are unable 

to prove this hypothesis to our satisfaction using 

either satellite or trajectory analysis. The volcanic 

clouds at the time of these encounters were not 

detectable by current satellite techniques. 

 

Acknowledgements

We gratefully acknowledge the comments of 

Geoffrey Garden (Bureau of Meteorology) and two 

anonymous NOAA reviewers, and the participation 

of colleagues from the Toulouse, Darwin and 

Washington VAACs in analysis of these events. We 

thank Steve Albersheim (FAA, USA), Frank H. 

Wells (Guam Weather Forecast Office), Marianne 

Guffanti (US Geological Survey), the airlines who 

anonymously provided details of the November 2002 

encounters, and the Rabaul Volcano Observatory and 

Air New Guinea for their provision of volcanic 

activity reports. 

References 

Casadevall, T. J., 1994. The 1989-1990 eruption of 

Redoubt Volcano, Alaska: impacts on aircraft operations. J. 

Volc. Geoth. Res., 62, 301-16. 

CMC, cited 2004, Atmospheric Transport Models for 

Environmental Emergencies. [Available online from 

http://www.mscsmc.ec.gc.ca/cmc_library/protected/PREVISIONS/e_8.pdf

(user: librarian; password: Books8 ).] 

Darwin Regional Specialised Meteorological Centre, 2003, 

Archived manual analyses. 

Draxler, R. R. and G. D. Hess, 1998. An Overview of the 

Hysplit_4 Modeling System for trajectories, dispersion, and 

deposition. Aust. Met. Mag., 47, 295-308. 

Draxler, R. R. and G. D. Rolph, cited 2003, HYSPLIT 

(HYbrid Single-Particle Lagrangian Integrated Trajectory) 

Model access via NOAA ARL READY Website 

(http://www.arl.noaa.gov/ready/hysplit4.html). NOAA Air 

Resources Laboratory, Silver Spring, MD. 

ICAO, cited 2004, International Civil Aviation 

Organization Handbook on the International Airways 

Volcano Watch (IAVW), 2nd edition. [Available online 

from http://www.icao.int/icao/en/anb/met/index.html.] 

Rabaul Volcano Observatory, 2003, Volcano Information 

Bulletins. 

Smithsonian Institution, cited 2004, Volcanic Activity 

Reports of the Global Volcanism Program, 

http://www.volcano.si.edu/gvp

Tupper, A., S. Carn, J. Davey, Y. Kamada, R. Potts, F. 

Prata, and M. Tokuno, 2004. An evaluation of volcanic 

cloud detection techniques during recent significant 

eruptions in the western 'Ring of Fire'. Remote Sens. 

Environ., 91, 27-46, doi:10.1016/j.rse.2004.02.004. 

Tupper, A. C. and K. Kinoshita, 2003. Satellite, air and 

ground observations of volcanic clouds over islands of the 

Southwest Pacific. South Pacific Study, 23, 21-46. 
P1.2 

Session 1 – Page 29 

SULFUROUS ODORS: A SIGNAL OF ENTRY INTO AN ASH PLUME—BUT PERHAPS LESS 

RELIABLE FOR ESCAPE 

Richard Wunderman, Global Volcanism Program, Smithsonian Institution, Washington, D.C. 

Although our understanding of odorous gases associated with volcanic ash plumes is incomplete, 

available reports indicate that during aircraft-ash encounters the pilots smelled sulfurous odors. Many 

people can smell the volcanic gases hydrogen sulfide (H2S, “rotten egg”) and sulfur dioxide (SO2, 

“struck-match”) at low concentrations––just a few parts per million (ppm). When subjects are exposed to 

sulfurous gases at slightly higher concentrations their smell receptors become saturated (undergoing 

‘olefactory fatigue’). Unless trained otherwise, pilots could arrive at the false sense that the gas is gone. 

Thus, pilots’ sense of smell should reliably signal entry into (or proximity to) an ash plume; in contrast, 

once in a plume with significant regions above the saturation threshold, pilots’ sense of smell could also 

mislead, providing a false sense of having emerged from the plume. Can such high concentrations occur? 

The few public records of aircraft-ash encounters suggest are inconclusive. Scientists have long known 

that large quantities of sulfurous gases escape during an eruption, but it is difficult to assess the gas 

concentrations of most ash plumes. Small droplets containing condensed sulfurous acids might also play a 

role. Thus, olefactory fatigue could plausibly present a very dangerous situation in the absence of other 

signs of entry into a plume (electrical discharges, clogged pitot tubes, etc.). Moreover, one could imagine 

the confusion induced by the perceived disappearance of the odor, as the aircraft penetrated into zones of 

higher or fluctuating H2S concentrations. Pilots training might include brief exposure to low 

concentrations of sulfurous gases, with discussion of the strengths and limitations of the sense of smell, 

the range of observations that might confirm the presence of an ash cloud, and procedures leading to 

reliably escaping a plume. Scientists need to establish whether critical concentration thresholds are likely 

to be exceeded in eruptive plumes. 
2.1 

Session 2 – Page 1 

A GLOBAL PERSPECTIVE ON VOLCANOES AND ERUPTIONS 

Richard Wunderman, Lee Siebert, James Luhr, Tom Simkin, Ed Venzke, 

Smithsonian Institution, Washington, D.C. 20560 USA 

Geologists have identified ~1500 volcanoes worldwide as probably active in the past 10,000 

years. Many form conspicuous, lofty cones; others include depressions, fissures, and areas 

peppered with vents. Most of these volcanoes reside on land or protrude above water. An 

additional, much larger number remain unwatched at depth beneath the sea, but their eruptions 

seldom break the surface. Towards the poles in places like Iceland, eruptions under thick glacial 

ice can melt an opening, allowing energetic discharges directly into the atmosphere. Volcanoes 

often occur in linear belts or chains; those along the Pacific Rim tend to erupt explosively. Many 

Asian air routes pass portions of Indonesia, the Philippines, and Japan, countries collectively 

home to over one-third of the known active volcanoes. Earth’s active volcanoes include ~10-15 

erupting (discharging solid material) nearly continually. At any one time, these are joined by 

several others, often those that have erupted in the recent past. During each year of the 1990s, 

~50-60 volcanoes erupted. Across the spectrum of explosive eruptions, smaller eruptions 

predominate. Many noteworthy eruptions started suddenly (over one-third reached climax 

within the first day; one-fifth in the first hour); however, in noteworthy cases years of milder 

eruptions preceded a climactic one. Such factors as the erupted material’s volume, discharge 

rate, viscosity, and volatile content influence the eruption’s size, character, and ash column 

height. No one phenomenon spawns large ash clouds. It is often difficult to gauge the ultimate 

size of an eruption at the onset. Although a growing ash column would hopefully trigger an 

immediate report to a VAAC, factors may thwart this effort (e.g., bad weather, darkness, limited 

infrastructure, damage, lack of diagnostic satellite coverage), thus halting clear, timely 

assessments. Half the world’s 1500 active volcanoes reside in developing nations; many of the 

world’s volcanoes lack dedicated monitoring instruments. 
2.2 

Session 2 – Page 3 

PROMISE AND PITFALLS IN ERUPTION FORECASTING 

Chris Newhall, US Geological Survey 

Box 351310, Univ. of Washington, Seattle, WA 98195 cnewhall@usgs.gov

“The problem with weather forecasting is that it’s 

right too often for us to ignore it and wrong too often 

for us to rely on it.” (Patrick Young) The same holds 

true for eruption forecasting. 

Weather forecasting, though not perfect, has 

improved greatly in recent decades. Volumes of data 

from ground, air, and space based sensors and 

sophisticated numerical models complement older 

methods. Daily trials in every forecast area help to 

refine the models. Hurricane (typhoon) and tornado 

forecasting carry greater uncertainties, limited by 

fewer data and opportunities for testing forecasts. 

Volcanic eruption forecasting has also improved in 

recent decades. Though uncertainties remain high, 

probably even higher than uncertainties in hurricane 

and tornado forecasts, dozens of successful eruption 

forecasts have been made since 1980 that saved tens 

of thousands of lives. True, volcanologists are 

handicapped by being limited to proxy or indirect 

measurements at the earth's surface rather than 

having direct measurements of the rising magma. 

True, only a few trials per year allow us to refine 

forecast methods. True, numerical forecast models 

are a dream of the future. However, today's and 

certainly tomorrow's eruption forecasts are important 

wake-up calls for plume detection and the variety of 

other ash-hazard mitigation measures described 

elsewhere in this volume. 

In this paper I'll say a few words about why 

volcanoes erupt, the basis for eruption forecasts, the 

relative reliability of various types of eruption 

forecasts, and some potential pitfalls of which you 

should be aware. 

First, what are eruptions? Eruptions are ejections of 

molten or solid rock, as flows or fragments, into the 

air or onto the earth's surface. In most cases the 

starting material of eruptions is molten rock (magma) 

that has risen from many miles depth, through the 

crust of the earth. If magma and its hot gases heat 

groundwater in the surrounding crust to sufficiently 

high temperatures and pressures, natural steam 

explosions will pulverize the older crust around the 

magma and cause that already solid rock to erupt as 

well. Many eruptions begin with such steam 

("phreatic") explosions and then become "magmatic" 

if magma itself reaches the surface. 

Phreatic explosions generate ash by pulverizing the 

rock through which they explode. Magmatic 

explosions generate ash by fragmenting the magma 

itself. Gases that are dissolved comfortably in magma 

at depth exsolve (i.e., un-dissolve) near the earth's 

surface, pressurize, and blow the magma into tiny 

sand- and silt-size fragments that we know as 

volcanic ash (fig. 1). Aside from minor differences 

in composition and shape, phreatic ash and magmatic 

ash are the same, i.e., tiny rock fragments, lofted into 

the air in thermals generated by the heat of exploding 

steam and magma. Small explosions may loft ash a 

few hundred or a few thousand feet above a vent; 

giant eruptions like that of Mount St. Helens in 1980 

or Pinatubo in 1991 loft ash 60,000-100,000 feet. A 

curtain of ash then rains out of an eruption plume, 

back down through all elevations. 

Ideally, forecasts of eruptions would specify their 

location, onset date, explosive magnitude, and 

duration or ending date. The most important for 

aviation safety are location, onset, and explosive 

magnitude (eruption column height, ash 

concentrations), joined soon after by ash trajectories. 

Current forecasts of duration or ending date are too 

imprecise to be helpful to the aviation community.

To forecast the location of volcanic eruptions is 

relatively simple if there is an adequate network of 

monitoring instruments. Nearly all eruptions are 

from preexisting volcanoes, and most though not all 

volcanoes that have erupted in recent history are 

monitored well enough to detect signs that might lead 

to an eruption (see Ewert and Newhall, this volume). 

As magma pushes its way toward the surface, it 

breaks the crust to make way. This process is 

recorded as tiny earthquakes by nearby seismometers. 

It also causes the earth's surface to bow slightly 

upward, detectable by sensitive surveying 

instruments including high-precision GPS stations. 

As gases that are dissolved in the magma at depth 

begin to exsolve, some leak out and can be detected 

by a variety of "gas sniffers" 
Session 2 – Page 4 

• IF magma has high viscosity

• --> gas not very mobile and

cannot escape easily

•IF magma ascends rapidly,

• --> high gas content persists

to near surface

• --> large potential expansion

silicate melt

+ dissolved gases (H2O, CO2, S)

(± crystals)

magma input from depth

Explosive

eruptions

After H Mader

 

 

Fig. 1. From Magma to Ash. Molten rock that contains 

dissolved gases (mostly, CO2 and H2O) rises buoyantly 

through a volcanic conduit. As it rises, confining pressure 

decreases (as when the cap of a carbonated drink is 

opened), bubbles form, expand, and eventually turn the top 

of the magma column into a magma foam. Rapid 

depressurization causes the foam to explode and pulverize 

tiny minerals and quenched (glass) bubble walls into 

volcanic ash. Heat from the hot ash causes the cloud to 

rise like a strong thermal. 

at the surface. Nearly always, we know which 

monitored volcanoes are restless and COULD erupt. 

 

To forecast the onset of an eruption is more difficult 

but sometimes possible. Some volcanoes exhibit 

exponentially escalating unrest and the onset of an 

eruption can be forecast to within a few hours or days 

(small eruptions of Mount St. Helens after the famous 

May 18 1980 events, a moderate-size initial eruption 

of Redoubt in December 1989, and progressively 

larger and eventually giant Pinatubo eruptions of 

June 1991). Sometimes, volcanoes also show a 

sudden, distinctive cessation of seismicity or gas 

emission, or a sudden tilting of ground very near a 

vent, that are extra signs that an eruption is imminent. 

Fortunately, volcanoes that have been quiet for many 

years and that are the most dangerous are usually the 

easiest at which to forecast eruption onset. 

Unfortunately, volcanoes that erupt frequently can 

erupt again with little notice, and volcanoes that have 

already been restless for an extended period can also 

erupt with little further notice (e.g., Mount St. 

Helens, May 18 1980). 

Forecasts of the explosive magnitude of an eruption 

are fraught with uncertainty. Two approaches are 

usually combined. The first is to review prior 

eruptions of that volcano and to assume that future 

eruptions will be of similar magnitude(s). Because 

many volcanoes erupt with a wide range of explosive 

magnitudes, we may have only statistical odds of one 

explosive magnitude vs. another. These odds can be 

refined slightly by factoring in the number of years 

the volcano has been quiet and the degree to which 

long quiescence at that volcano makes subsequent 

eruptions more explosive. Not all volcanoes behave 

alike, though, and some volcanoes even change their 

general eruptive style from decade to decade or 

century to century. 

A second way to forecast explosive magnitude looks 

for telltale indications in precursory unrest. Some 

indicators include the speed with which magma is 

rising (faster speed correlates with higher eventual 

explosivity), recent gas emissions (to judge whether 

the new magma remains gas-charged or has already 

lost its fizz and explosive potential), and, perhaps, the 

apparent volume of rising magma as indicated by 

bowing up of the ground surface. Truth be told, 

though, we have had very few opportunities to test 

the consistency and thus reliability of these 

indicators. 

 

At best, explosive magnitude can be forecast to the 

nearest order of magnitude of how much magma will 

be fragmented into ash (e.g., 0.01, 0.1, 1, 10, or 100 

cubic miles of magma) and the nearest 20,000 or 

30,000 feet of eruption column height. Many 

volcanologists use a shorthand index of explosive 

magnitude, called the Volcanic Explosivity Index or 

VEI (Newhall and Self, 1982). Successively higher 

VEI values refer to roughly one order of magnitude 

greater ash volume and successively higher 

maximum column heights. Of the 60 or so nonsubmarine volcanoes around the world that are active 

each year (Wunderman and others, this volume), 

most are producing VEI 2 eruptions from which ash 

rises between 3,000 and about 20,000 feet. VEI 2 

eruptions generally don't threaten commercial jet 

traffic at cruise altitude but can certainly cause 

problems for low-flying aircraft, planes on ascent or 

descent, and for airports themselves. VEI 3 and 

higher eruptions, of which there are typically several 

per year worldwide, generally do send ash to cruise 

altitudes and are serious aviation hazards. If a 

volcano is expected to erupt and is known to produce 

VEI 3 and larger eruptions, it would be prudent to 

assume that the impending eruption could be that 

large until proven otherwise. Satellite imagery 

combined with a measure of seismic tremor 

associated with an eruption (McNutt, 1994) can often 

give an estimate of column height within an hour 

after eruption onset, supplanting whatever was 

forecast, but be aware that eruptions often increase or 

decrease in VEI from hour to hour and day to day. In 

more than 90 % of eruptions, the climax (maximum 
Session 2 – Page 5 

explosive magnitude) is reached in the first 24 hours 

(Simkin and Siebert, 1984), but tall eruption columns 

can also pop up later in eruptions! 

What determines the ultimate explosive magnitude of 

an eruption? In a word, gas! More precisely, 

explosivity is controlled by how much gas was 

originally contained in the magma and how much of 

that has bled off before the magma reached near the 

earth's surface. The analogy between magmas and 

soda pop is actually quite good. Gas-charged soda 

pop will explode if opened suddenly, but if opened 

slowly its gas will just bleed off. Without trying here 

to quantify these parameters, we can generalize that if 

magma is relatively fluid and/or is rising slowly, 

most of its gas may be able to bleed off before that 

magma nears the surface. Its resulting explosive 

potential will be low. This is true of fluid Hawaiian 

magmas and of very viscous magmas beneath some 

lava domes. In contrast, if gas-rich magma is too 

viscous to let gases escape easily and if it rises fast 

enough that the gases can't bleed off before nearing 

the surface, the explosive potential will be high. This 

is characteristic of most volcanoes of the CircumPacific "Ring of Fire" and most volcanoes in Italy, 

Greece, and Iceland. Some volcanoes like Soufrière 

Hills on Montserrat exhibit both behaviors -- nonexplosive dome growth when the supply and ascent 

rate of magma is slow and explosive eruptions when 

it is high. At a few volcanoes like Stromboli in Italy, 

the ascent rate is just right to maintain constant small 

explosions -- high enough to not lose all of its gas 

enroute to the surface yet low enough to lose enough 

gas to keep explosions small. 

I should add words of caution about “non-explosive” 

dome building eruptions and secondary explosions. 

Even though lava domes may grow without 

explosions, those that are actively growing, 

especially if on steep slopes, tend to collapse and 

produce what we call dome-collapse pyroclastic 

flows. These are hot avalanches and have significant 

dust (ash) clouds. Because the lava is hot, these 

winnowed ash clouds can rise in thermals to 

thousands, even several tens of thousands of feet, i.e., 

up into cruise altitudes. Dome collapse and 

associated ash clouds are very difficult to forecast 

and, at this point, the best that can be done for 

warning of these is near-real time detection and 

tracking, alerted by the seismicity of the collapse. 

“Secondary explosions” occur where pyroclastic flow 

deposits are thick and remain hot for months or even 

years and groundwater seeps into the deposit, is 

heated, and flashes into steam. Most such events are 

too small for aviators to worry about, e.g., lofting ash 

only a few hundred feet at Redoubt Volcano in 1990, 

but the largest secondary explosions from thick 

deposits on the slopes of Mount Pinatubo occurred 

months after the main eruption, with only rainfall as 

warning, and sent ash 80,000 feet into the air and 

damaged at least one commercial jet. 

 

Conventional wisdom is that after an eruption, 

magma that remains in the volcano's conduit cools 

and solidifies ("freezes"), forming a plug that will 

have to be cracked or blasted out before the volcano 

can erupt again. Such "closed-vent" behavior is 

characterized by infrequent, often explosive 

eruptions. However, many volcanoes exhibit "openvent" behavior in which magma in the conduit does 

not solidify between eruptions but, instead, churns in 

a kind of lava-lamp-like convection. Rising, gas-rich 

magma grows less and less dense as gas bubbles 

grow in it, eventually turning into a magma foam not 

far below the surface. Foams are permeable and 

most of the gas escapes, feeding persistent gas 

plumes from such volcanoes. The degassed foam 

collapses, becomes dense, and sinks back down 

through the fresh rising magma, driving the 

convection process. If the reservoir of gas-rich 

magma is large enough, this activity can persist and 

feed small eruptions for years or even decades, e.g., 

Stromboli, Italy and Yasour, Vanuatu. Some 

volcanologists think the same is occurring beneath 

other volcanoes that in recent years have produced a 

lot of gas and not much else, e.g., Popocatépetl in 

Mexico. 

 

Closed-vent behavior makes eruptions relatively easy 

to forecast. Fresh magma working its way to the 

surface must break through the plug or surrounding 

rock, generating earthquakes and swelling of the 

ground. Gas leaks may or may not be detected at the 

surface. The most easily measured gas, sulfur 

dioxide, may be absorbed into and hidden in 

groundwater and thus not reach gas instruments on 

the surface. Fortunately, most VEI 3 and larger 

eruptions are going to follow closed-vent behavior 

and thus will give at least some warning of 

reawakening. 

Open-vent behavior tends to bleed off the gas and 

thus reduce explosive potential. Thus, most eruptions 

during this behavior will be VEI 2 and smaller. 

However, be careful, because there are some cases in 

which either the convection speeds up (increasing 

explosive potential) or is temporarily stopped 

(trapping gas and thus also increasing explosive 

potential). Eruptions from volcanoes in open-vent 

behavior are generally difficult to forecast because 

there is virtually no plug to break through. Seismic 

and ground deformation precursors will be minimal. 
Session 2 – Page 6 

Emission of CO2, SO2, and other volcanic gases may 

increase notably, but these don't indicate likely onset 

time very precisely. Ground deformation (e.g., tilt) 

measurements right on crater rims can warn of fresharriving slugs of magma and thus of explosions or 

dome collapse to follow within hours to a few days, 

but very few volcanoes have instruments close 

enough to their vents to detect such changes. So, in 

general, eruptions during open-vent behavior will be 

difficult to forecast. As an example, after the vent of 

Mount Spurr, Alaska, was opened in June 1992, a 

second eruption in August began without clear 

seismic precursors. 

Throughout this paper I have been referring to 

eruption forecasts as if they are issued in a standard 

format. In reality, they are not. Three related 

formats illustrate. 

One format of eruption forecasts explicitly states one 

or several progressively narrower time windows, e.g., 

2 weeks, 1 day, etc., within which an eruption is 

expected to begin (e.g., Swanson and others, 1983; 

Punongbayan and others, 1996). Very few forecasts 

are this explicit, although one successful one from 

Pinatubo (1991) was instrumental in saving many 

lives. Equally few specify the exact magnitude of an 

impending eruption; more often, forecasts give a 

range of likely magnitudes. 

A second format estimates relative and absolute 

probabilities of all likely outcomes, usually in the 

form of a probability tree that applies to a specified 

timeframe (Aspinall and others, 2002; Newhall and 

Hoblitt, 2002; Marzocchi and others, in press). 

The third, most common format (with many variants) 

is a color or numerical code that is shorthand for the 

intensity of seismic and other unrest, level of 

volcanologists' concern, OR proximity of the onset of 

an eruption. Most such codes have 3-6 levels of 

which the lowest is background activity and the 

highest is a dangerous explosive eruption in progress. 

Steps between these two extremes represent 

increasing hazard but may not specifically "forecast" 

an eruption. Rather, they represent DECREASING 

ASSURANCE that an eruption will NOT occur. 

Although this might seem like a fine distinction I 

think it is an important one, as there are still many 

instances in which we know that present unrest 

COULD presage an eruption but could equally well 

stop without eruption. Volcanologists try very hard 

to avoid false alarms, i.e., to not "cry wolf," and color 

codes that can be raised or lowered are more flexible 

than forecasts of when a volcano WILL erupt. The 

International Civil Aviation Organization (ICAO, 

2004) describes its color-code scheme, and task 

groups within the US Geological Survey (Gardner, 

this volume) and the International Association of 

Volcanology and Chemistry of the Earth's Interior 

(IAVCEI) are exploring whether wider 

standardization is possible. 

The three formats of forecasts are broadly related. 

Yellow or similar codes indicate elevated but not 

intense unrest, and generally do not imply that an 

eruption will occur. Indeed, more often than not, 

yellow unrest will stop without an eruption. Many 

instances of orange or similar unrest typically are 

followed by an eruption within days to weeks, so 

there is an implication, tacit or explicit, that an 

eruption could and in some cases probably will begin 

within that timeframe. The highest level of alert, red 

or similar, may indicate that an eruption is likely 

within hours or has already begun. Please note use of 

the terms "could" and "likely," rather than "will 

occur." Observatories may use different formats for 

different audiences or to emphasize time of onset, 

type of eruption, or simplicity and possible relation to 

response plans, respectively. 

Weather forecasters track how often their forecasts 

are correct or incorrect. Can we do the same for 

eruption forecasts? Of 224 moderate-size 

explosions during a 1987-1991 test period at 

Sakurajima Volcano, 162 were successfully forecast 

and 62 were missed (Kamo and others, 1994). An 

automated algorithm produced only a few false 

alarms. Twenty (20) post-climactic, mostly domebuilding eruptions of Mount St. Helens were 

successfully forecast between 1980 and 1986 without 

false alarms or misses (Swanson and others, 1983; 

Swanson, 1990). 

Color-code or numerical alerts do not specifically 

forecast dates of eruptions but, at higher levels, 

usually imply a timeframe of weeks or less. Within 

the past 20 years but not including Sakurajima and 

Mount St. Helens events, 60 orange, red, or similar 

alerts were followed by eruptions within weeks or 

less, 8 orange or red alerts were “false alarms,” i.e., 

NOT followed shortly by eruptions, and 48 eruptions 

were missed. Many in the last group were 

anticipated with a yellow alert but not with a more 

urgent orange or red alert. 

Of roughly 150 VEI ≥3 eruptions that occurred from 

mid-1984 to mid-2004 – eruptions that are always of 

concern to aviation -- about 30 were successfully 

forecast with an orange or red alert and 50-100 were 

loosely anticipated by a yellow or equivalent alert, 

but at least several tens were not anticipated at all. 
Session 2 – Page 7 

The last group occurred where volcanoes were not 

monitored or where the observatory failed to issue an 

alert. These unforetold VEI ≥3 eruptions are 

worrisome and unacceptable, and their source 

volcanoes are slowly being brought under monitoring 

surveillance. 

Eruption forecasting is improving slowly but surely. 

Part of the improvement comes from expanded and 

better monitoring and a growing body of experience 

about what precursors to expect. Another part comes 

from improving conceptual models of how magma 

rise and degas, or, if not, explode. Clearly, not all 

eruptions are being forecast yet, but are the forecasts 

that are issued reliable? Since volcano observatories 

are careful to not issue false alarms, most orange, red, 

or equivalent warnings are likely to be correct and 

can help you to be ready for ash as soon as an 

explosive eruption does begin. 

References: 

Aspinall WP, Loughlin SC, Michael FV, Miller AD, 

Norton GE, Rowley KC, Sparks RSJ, Young SR, 

2002, The Montserrat Volcano Observatory: its 

evolution, organization, role, and activities, in Druitt 

TH, Kokelaar BP, eds., The eruption of Soufrière 

Hills Volcano, Montserrat, from 1995 to 1999. 

London, Geol Soc London, p. 71-91 

Ewert JW, Newhall CG, this volume, Status of 

volcano monitoring worldwide 

Gardner CA, Guffanti MC, Heliker CC, Hill DP, 

Lowenstern JB, Murray TL, this volume, A proposed 

alert-level notification scheme for aviation and 

ground-based hazards at U.S. volcanoes. 

ICAO (International Civil Aviation Organisation), 

2004, Handbook on the International Airways 

Volcano Watch, ICAO Document 9766-AN/968, 

http://www.icao.int/icaonet/dcs/9766_2_en.pdf 

Kamo K, Ishihara K, Tahira M, 1994, Infrasonic and 

seismic detection of explosive eruptions at 

Sakurajima Volcano, Japan, and the PEGASUS-VE 

early-warning system, in Casadevall TC, ed., 

Volcanic Ash and Aviation Safety, Proceedings of 

the First Intl Symposium on Volcanic Ash and 

Aviation Safety, US Geological Survey Bull 2047, p. 

357-365 

 Linde AT, Sacks S, 2000, Real time predictions of 

imminent volcanic activity using borehole 

deformation data (abstr.), EOS, v. 81:48, p. F1253 

Marzocchi W, Sandri L, Gasparini P, Newhall C, 

Boschi E, in press, Quantifying probabilities of 

volcanic events: the example of volcanic hazard at 

Mt. Vesuvius. J Geophys Res 

McNutt SR, 1994, Volcanic tremor amplitude 

correlated with volcano explosivity and its potential 

in determining ash hazards to aviation, in Casadevall 

TC, op. cit., p. 377-385 

Newhall CG, 2000, Volcano Warnings. In 

Sigurdsson H, Houghton, B, McNutt, SR, Rymer H, 

and Stix J, eds., Encyclopedia of Volcanoes, 

Academic Press, San Diego, p. 1185-1197 

Newhall CG, Hoblitt RP, 2002, Constructing event 

trees for volcanic crises. Bull Volcanol, v. 64, p. 3-

20 

Newhall CG, Self S, 1982, The Volcanic Explosivity 

Index (VEI): an estimate of explosive magnitude for 

historical volcanism. Jour Geophysical Research, v. 

87, p. 1231-1238 

Punongbayan RS, Bautista MLP, Harlow DH, 

Newhall CG, Hoblitt RP, 1996, Pre-eruption hazard 

assessments and warnings, in Newhall CG, 

Punongbayan RS, eds., Fire and Mud, PHIVOLCS, 

Quezon City and Univ. of Washington Press, Seattle, 

p. 67-85 

Scott B, this volume, Volcanic alert systems: an 

overview of their form and function. 

Simkin T, Siebert L, 1984, Explosive eruptions in 

space and time, in Explosive Volcanism: Inception, 

Evolution, and Hazards, National Academy Press, p. 

110-121 

Simkin T, Siebert L, 1994, Volcanoes of the World, 

2nd ed., Geoscience Press, Tucson, 349 p. 

Swanson DA, Casadevall TJ, Dzurisin D, Malone 

SD, Newhall CG, and Weaver CS, 1983, Predicting 

eruptions at Mount St. Helens, June 1980 through 

December 1982: Science, v. 221, p. 1369-1376 

Swanson DA, 1990, A decade of dome growth at 

Mount St. Helens, 1980-90: Geoscience Canada, v. 

17, p. 154-157. 

Wunderman R, Siebert L, Luhr J, Simkin T, Venzke 

E, this volume, A global perspective on volcanoes 

and eruptions
2.3 

Session 2 – Page 9 

STATUS AND CHALLENGES OF VOLCANO MONITORING WORLDWIDE 

John W. Ewert, U.S. Geological Survey, Vancouver, WA 98683, USA (jwewert@usgs.gov) 

Christopher G. Newhall, U.S. Geological Survey, Seattle, WA 98195 USA 

Introduction 

Volcanoes exhibit precursory activity that may 

occur hours to years before an eruption and thus 

allow an eruption forecast. Accurate forecasts and 

real-time detection of volcanic eruptions are 

essential to keep pilots, passengers, and planes out 

of ash clouds. Timely eruption reporting by 

volcano observatories, beginning with information 

about the premonitory build-up phase, allows 

more time for flight planning and improves 

response time of satellite-based ash-cloud 

detection. Here we describe in general terms the 

most commonly used volcano-monitoring 

techniques, and report where obvious gaps in 

monitoring exist, particularly with respect to 

aviation safety. 

Most volcano-monitoring networks and 

observatory operations have been designed to 

mitigate hazards to people on the ground rather 

than in the air. Consequently, most volcano 

observatories and hence most monitored volcanoes 

are found where the risks to people on the ground 

are greatest. Notable exceptions are the 

monitoring of Alaskan volcanoes by the Alaska 

Volcano Observatory (AVO) (Murray, this 

volume), Kamchatkan and Kurile volcanoes by 

KVERT (Gordeev and others, this volume), and 

Anatahan volcano by the U.S. Geological Survey 

and the Commonwealth of the Northern Mariana 

Islands. At the present time, volcano-monitoring 

operations are conducted by about 60 institutions 

globally. However, of the more than 1500 active 

volcanoes in the world, less than a quarter have 

any kind of real-time monitoring, and only a few 

(numbering less than 50) would be considered 

adequately monitored for both hazard and research 

purposes. 

Why is ground-based monitoring critical? 

A recent eruption at Anatahan volcano in the 

Commonwealth of the Northern Mariana Islands 

(CNMI) in 2003, gives an example of the time lag 

between eruption onset and ash cloud detection 

that can occur in a remote area if only remote 

sensing is employed. On 10 June 2003, 

approximately five hours elapsed from the 

unexpected onset of eruptive activity at Anatahan 

and subsequent ash plume to 11 km, to the 

issuance of the first Significant Meteorological 

Advisory (SIGMET) and Volcanic Ash Advisory 

by the Guam Meteorological Watch Office 

(MWO) and Washington-Volcanic Ash Advisory 

Center (W-VAAC), respectively (Guffanti and 

others, in press). Arguably, had Anatahan been 

seismically monitored in real time before the start 

of eruptive activity, this delay likely could have 

been much shorter and dissemination of ashhazard information to the aviation sector could 

have been more rapid. Luckily, no damaging 

encounters appear to have occurred. 

Subsequently, real-time seismic monitoring was 

installed on Anatahan by the U.S. Geological 

Survey and the CNMI Emergency Management 

Office, and in March and April of 2004 notices of 

new eruptive activity at Anatahan were passed to 

the W-VAAC and Guam MWO within minutes of 

seismic detection (R.White, written 

communication). 

When ground-based monitoring is in operation at a 

volcano, and communication links are in place 

between the volcano observatory and the regional 

MWO and VAAC, notices of heightened eruption 

potential and notification of eruption onset are 

typically more rapid than if no ground-based 

monitoring is in place. The eruption of remote 

Bezymianny Volcano, Kamchatka in June, 2004, 

illustrates this case. On June 16, 2004, based on 

increasing seismicity, the Kamchatkan Volcanic 

Eruption Response Team (KVERT) raised the 

concern color code for Bezymianny from yellow 

to orange (indicating an eruption is possible within 

a few days and may occur with little or no 

warning). On June 18, 1940 UTC an explosive 

eruption was detected seismically, and an ash 

column to 8-10 km was observed by a remotely 
Session 2 – Page 10 

operated video camera at 2040 UTC. KVERT 

issued an eruption notification at 2055 UTC, a 

little more than one hour after the eruption began. 

In contrast, owing to a lack of satellite coverage, 

the ash column was first spotted in satellite 

imagery approximately 4 hours after the 

seismically-determined eruption onset. (D. 

Schneider, personal communication). 

Although the eruption notification was not made 

within five minutes of the eruption onset as airline 

representatives to the 2nd International Conference 

on Volcanic Ash and Aviation Safety suggested as 

a goal, the notification was much more timely than 

would have been possible with only satellite 

remote sensing owing to the ground-based 

monitoring by the KVERT. No damaging 

encounters were reported from this eruption. 

Real-time volcano monitoring 

An adequately monitored volcano has continuous 

multiparametric (a combination of seismic, 

deformation, geochemical, etc.) data streams that 

are available in real-time to an observatory 

facility. More commonly in the world today, if a 

volcano has any monitoring at all, it is by a single 

seismometer, standalone or within a regional 

network. 

For the purposes of this discussion, we classify 

volcano monitoring techniques into two general 

classes; those useful for eruption forecasting and 

prediction, and those useful for eruption detection. 

We limit our discussion to those techniques and 

instruments that can be used in real time or nearreal time, generally in a telemetered configuration. 

A combination of monitoring techniques and 

sensor types yields the most reliable results. 

Eruption forecasting tools 

Seismic monitoring is the mainstay of volcano 

monitoring operations around the world. The 

typical telemetered seismic station used to monitor 

a volcano is a single (vertical) component , shortperiod type, data from which are sent via analog 

telemetry to a central recording site. This class of 

instrumentation has been employed to monitor 

volcanoes since the early 1970s, is robust even in 

marginal field conditions, and the technology is 

accessible in developing countries. To locate 

seismicity, a minimum of four telemetered 

instruments spread around the volcano is 

necessary. In many cases though, only one or two 

instruments may be deployed close enough to a 

volcano to reliably detect and track the subtle 

changes in seismicity prior to eruption. 

Fortunately, useful information about the status of 

a volcanic system can be gleaned from one or two 

stations if an experienced seismologist is on hand 

with appropriate data processing software 

(McNutt, 1996). 

At well-monitored volcanoes, which number less 

than 50 worldwide, focused, small-aperture 

seismic networks are arrayed within a larger 

aperture regional network and may consist of a 

mix of single and three-component stations. 

Focused seismic monitoring techniques can be 

used to infer the presence of magma as a cause of 

seismicity, to track the ascent of magma and other 

fluids toward the surface, and to determine the 

onset of explosive eruptions. 

Other monitoring techniques used to forecast and 

predict eruptions include methods to measure 

ground movement (deformation), gas emissions, 

and changes in thermal characteristics. 

Telemetered deformation instrumentation includes 

(in order of increasing sensitivity) Global 

Positioning System (GPS) installations, which 

measure surface displacement in three dimensions; 

tiltmeters, which measure changes in near-surface 

ground inclination; and strainmeters, which 

measure minute compressional or tensional 

changes in strain in boreholes that are 10s to 100s 

of meters deep. Monitoring ground movement by 

remote sensing over broad areas is sometimes 

possible with Interferometric Synthetic Aperture 

Radar (InSAR). The InSAR technique lends itself 

to tracking slow, long-term changes that may 

occur months to years ahead of an eruption. 

Together, these deformation-monitoring 

techniques can detect accumulation of magma 

beneath a volcano and the passage of magma 

toward the surface (Dvorak and Dzurisin, 1997). 

Carbon dioxide, sulfur dioxide and hydrogen 

sulfide gas fluxes can be determined by flying 

monitoring instruments beneath and through the 

volcanic gas plume near the volcano. Sulfur 
Session 2 – Page 11 

dioxide flux can be measured from the ground in 

daylight hours and the data telemetered. Changes 

in concentrations of gas species in soil or 

fumaroles can also be measured, and the data 

telemetered to a central receiving site. Though not 

measurements of the total gas flux from the 

magmatic system, these types of data can be useful 

in tracking a volcanic system moving toward 

eruption. These techniques can confirm the 

presence of an active, degassing magma body and 

be used to infer rise of magma to shallow levels 

beneath a volcano and/or boiling and 

disappearance of groundwater in response to 

increased thermal flux (Symonds and others, 

1994).

The extent and intensity of thermal emissions from 

a volcanic source can be measured in a variety of 

ways including satellite, aircraft, and ground based 

measurements. Used in conjunction with other 

monitoring techniques, thermal monitoring can aid 

in diagnosing whether a restless volcano is 

progressing toward eruption. 

Eruption detection tools 

Explosive volcanic eruptions can create a sudden 

ash hazard to aircraft, necessitating the shortest 

possible delay between eruption detection and 

issuance of warnings. While satellite remote 

sensing offers attractive eruption detection 

capabilities owing to broad areal coverage and 

multi-spectral capabilities, uncertainties in cloud 

cover, eruptive column height, orbital timing of 

Polar Operational Environmental Satellites and 

scan timing of Geostationary Operational 

Environmental Satellites make timely detection of 

eruptions from space a hit or miss proposition 

(Mouginis-Mark and Domergue-Schmidt, 2000). 

Ground-based instrumental monitoring, used in 

conjunction with satellite remote sensing offers a 

much higher probability of timely detection of 

eruption onsets. 

As with eruption forecasting, seismic monitoring 

is the mainstay of eruption detection at volcano 

observatories. Other techniques used to detect and 

confirm eruptions include infrasonic and lightning 

detection, direct human observations, weather 

radars and video surveillance. A combination of 

different sensors coupled with effective 

communication between observers and the 

aviation community offer the best chance of 

timely ash cloud avoidance by aircraft. 

Current Status 

The number of monitored volcanoes has increased 

in most regions since the First International 

Symposium on Volcanic Ash and Aviation Safety 

in 1991 (Casadevall, 1994). About 270 of 470 

explosive volcanoes that have erupted in past 2000 

years have some form of continuous monitoring in 

place (fig. 1). The majority have only seismic 

monitoring—in many cases a single sensor. Wellmonitored volcanoes tend to be in wealthy 

countries, exhibit some level of unrest, have 

erupted recently, and/or pose a clear hazard to 

densely populated areas. The corollary is that 

there are about 200 recently active volcanoes with 

explosive potential that remain unmonitored. 

With the exception of the monitoring being carried 

out in the Aleutian Islands by the Alaska Volcano 

Observatory Murray, 2004), Kamchatkan and 

northern Kurile volcanoes by KVERT (Gordeev, 

this volume), and Anatahan volcano by the U.S. 

Geological Survey and the CNMI, aviation risk 

has not been the determining factor in where 

volcano networks are established. Usually the first 

priority of the institution doing the monitoring is 

the safety of people in hazardous areas nearby the 

volcano. Volcano observatories typically issue 

public notifications of conditions at monitored 

volcanoes, but again, the focus is typically on 

warnings about ground hazards. 

Although more volcanoes are monitored now than 

ever before, there are still large portions of 

volcanic arcs that remain un-monitored, including 

volcanoes that seriously threaten airways (fig. 1). 

The most under-monitored volcanic areas include 

the Northern Mariana Islands, the Kurile Islands 

and parts of Kamchatka, the central and southern 

Andes of South America, and Africa. Not 

surprisingly, these are areas with the smallest 

ground populations at risk. 
Session 2 – Page 12 

Challenges 

More volcanoes along busy air routes are 

continuously monitored now than at the time of 

the first Volcanic Ash and Aviation Safety 

Conference 13 years ago. Encounters are fewer 

today than 13 years ago (Guffanti and others, this 

volume). Yet, encounters with ash still occur. We 

in the volcanological community are proud of our 

improvements in monitoring, but we’re still not 

satisfied and the aviation community shouldn’t be 

either. Here are several targets toward which 

volcanologists, meteorologists, air traffic control, 

pilots, and airlines together should strive: 

1) Add monitoring as quickly as possible to the 

~200 volcanoes that are potentially active and may 

pose a threat to aviation, but are still unmonitored. 

Can we halve that number of unmonitored within 

the next 10 years? 

2) Strengthen monitoring at minimally-monitored 

volcanoes, so that no eruption will be missed. 

3) Ensure that communications between volcano 

observatories and VAACs are fast, clear, and 

robust. One way to improve this communication 

and awareness of each others’ work would be to 

increase near-real-time data sharing. Through the 

internet, volcano observatories could share graphic 

seismic data with their VAAC(s) and VAACs 

could share selected satellite imagery (e.g., GOES 

or GMS images) with their cooperating volcano 

observatories. 

4) A clear and worthy target is to notify pilots of 

an ash-producing eruption within 5 minutes of its 

onset. Work together to ensure adequate funding 

for these efforts. Specifically, pilots, airline 

companies, and those in air traffic control need to 

help volcanologists and meteorologists tally (a) 

encounters and details of their consequences, (b) 

diversions (avoided encounters) and probable 

savings (c) the volume of air traffic in undermonitored volcanic areas. These data are sorely 

needed to justify measures and expenses that each 

of the abovementioned players would make in the 

overall mitigation effort. 

References Cited 

Casadevall, T.J., ed., 1994, Volcanic ash and 

aviation safety: Proceedings of the first 

international symposium on volcanic ash 

and aviation safety: U.S. Geological 

Survey Bulletin 2047, 449 p. 

Casadevall, T.J., Thompson, T.B., and Fox, T., 

1999, World map of volcanoes and 

principal aeronautical features: U.S. 

Geological Survey Geologic 

Investigations Series Map I-2700 

Dvorak, J.J. and Dzurisin, D., 1997, Volcano 

Geodesy: The search for magma 

reservoirs and the formation of eruptive 

vents: Reviews of Geophysics, v. 35, no. 

3, p. 343-384. 

Gordeev, E., Senjukov, S., and Girina, O., 2004, 

Monitoring and reporting of Kamchatkan 

volcanic eruptions: this volume. 

Guffanti, M.C., Casadevall, T.J., and Mayberry, 

G.C., Reducing Encounters of aircraft 

with volcanic-ash clouds: this volume 

Guffanti, M.G., Ewert, J.W., Gallina, M., Bluth, 

G. S. J., and Swanson, G.L., in press, The 

Volcanic-Ash Hazard to Aviation During 

the 2003-2004 Eruption of Anatahan 

Volcano, Commonwealth of the Northern 

Mariana Islands: Journal of Volcanology 

and Geothermal Research. 

McNutt, S.R., 1996, Seismic monitoring and 

eruption forecasting of volcanoes: a 

review of the state-of-the-art and case 

histories, in Scarpa, R. and Tilling, R.I., 

eds., Monitoring and mitigation of 

volcano hazards: New York, SpringerVerlag, p. 99-146. 

Mouginis-Mark, P.J., and Domergue-Schmidt, N., 

2000, Acquisition of satellite data for 

volcano studies, in Mouginis-Mark, P.J., 

Crisp, J.A., and Fink, J.H., eds., Remote 

sensing of active volcanism: American 

Geophysical Union Geophysical 

Monograph 116, p.9-24. 

Murray, T.L., 2004, The Alaska Volcano 

Observatory – Fifteen years of working to 

mitigate the risk to aviation from volcanic 

ash in the North Pacific: this volume. 
Session 2 – Page 13 

Siebert, L., and Simkin, T., 2002-, Volcanoes of 

the World: an Illustrated Catalog of 

Holocene Volcanoes and their Eruptions. 

Smithsonian Institution, Global Volcanism 

Program Digital Information Series, GVP3, (http://www.volcano.si.edu/gvp/world/). 

Symonds, R.B., Rose, W.I., Bluth, G.J.S., and 

Gerlach, T.M., 1994, Volcanic-gas 

studies: Methods, results, and 

applications, in Carroll, M.R. and 

Holloway, J.R. eds., Volatiles in Magmas: 

Mineralogical Society of America 

Reviews in Mineralogy, v. 30, p. 1-66.

Figure 1. Map showing 468 volcanoes that have erupted explosively in the last 2000 years. 

Monitored volcanoes indicated by solid triangles. Un-monitored volcanoes indicated by open 

circles. Volcano data from Siebert and Simkin, 2002-. Flight routes from Casadevall and others, 

1999. Monitoring status compiled by the authors. 
Session 2 – Page 14 
2.4 

Session 2 – Page 15 

VOLCANIC ALERT SYSTEMS: AN OVERVIEW OF THEIR FORM AND FUNCTION 

Bradley Scott, Institute of Geological and Nuclear Sciences, Wairakei, New Zealand 

Volcanic activity world wide is monitored by over 60 Volcano Observatories. Individual 

volcano observatories can be responsible for anywhere from one to over 40 volcanoes. They 

are typically set up to advise national, regional or local governments, emergency responding 

agencies, industry and the population. This advice is usually communicated by ‘volcano alert 

bulletins’ and ‘volcano alert levels’. A wide variety of needs are catered for in these systems. 

Two basic styles of volcano alert/warning systems have developed which relate to the status 

of a volcano, i.e. is it frequently in eruption or is it reawakening? Systems dealing with 

frequently active volcanoes have steps in them that are typically linked to the ‘current’ status 

of the volcanic activity, especially ongoing eruptive activity. They can carry any element of 

prediction, forecasting or warning and some indication of the degree of risk that the public 

are placed in while undertaking normal (non-restricted) activity on or about the volcano. In 

contrast, systems based on expected activity (reawakening) are often based on time-windows 

to the next expected level of unrest or the commencement of eruptive activity. The window 

durations are typically years, months, days or hours. The structure and responses to the alert 

systems vary between countries, resulting in a lack of international uniformity in our alertwarning systems, however this does not undermine the important function they achieve. 
2.5 

Session 2 – Page 17 

EXPLOSIVE ERUPTIONS OF ETNA VOLCANO SERIOUSLY 

THREATEN AVIATION SAFETY IN THE 

CENTRAL MEDITERRANEAN REGION 

Mauro Coltelli and Paola Del Carlo 

Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Catania, Piazza Roma 2, 95123, 

Catania, Italy 

Etna is a basaltic volcano located in eastern 

Sicily (Italy). Although it is worldwide known 

for lava flow eruptions that often threat the 

populated areas on its slopes, in the last decades 

explosive eruptions represent its more frequent 

activity either at summit craters or along 

fissures opened on its flanks, making Etna 

volcano a serious source of risk for aviation in 

central Mediterranean region (Fig. 1). 

The frequency of Etna’s eruptive phenomena in 

the last four centuries has increased, and 

particularly the explosive eruptions since 70’s 

years (Branca and Del Carlo, 2004a). From 

1979, we surveyed a large number of violent 

explosive events (Fig. 2) produced by summit 

craters, including more than 150 lava fountain 

episodes, characterized by: i) eruptive columns 

from 2 to 15 km high above the vent, ii) tephra 

volumes ranging from 104

 to 107 m3 and iii) 

magnitude from violent strombolian to 

subplinian. They often produced tephra fallout 

over eastern Sicily and the city of Catania. 

Fig. 1: 2001 eruption plume of Etna in the 

Mediterranean Sea (NOAA courtesy). 

Fig. 2: Frequency of Etna’s explosive eruptions 

occurred in the last 25 years. 

At summit craters the prolonged explosive 

activity is generally weaker and produces 

limited dispersed tephra fallout, whereas violent 

strombolian and subplinian types episodes from 

summit craters are short-lived eruptions (from 

less than one hour to few hours) that produce 

widely dispersed deposits up to a few hundred 

km from the volcano. Due to the small volume 

of magma erupted they are not able to produce 

serious damages to the infrastructures also close 

to the volcano but they produce or induce 

several collateral damages mainly to the human 

health (lung ingestion of very small particles), 

to agriculture (lost of harvests), to the aviation 

(in-flight encounters with the drifting ash cloud 

and airport’s runway contaminated with ash) 

and to the surface mobility (slippery roads due 

to a continuous ash mantle). These events are 

often repeated in a short time as in September 

1989, when 14 episodes occurred during 16 

days; in 1990 when other five episodes 

occurred; between November 1995 and June 

1996 when ten strong fire fountain episodes 

were produced by North East Crater; during 

1997 with other 14 episodes mainly from South 

East Crater; in 1998-9 when 4 episodes 

occurred, and finally the extraordinary activity 

0

10

20

30

40

50

60

70

1979198119831985198719891991199319951997199920012003
Session 2 – Page 18 

of 2000 when 64 episodes occurred during five 

months causing the first serious problems to the 

population of eastern Sicily for the damages to 

aviation, to agricultures, and to roads and 

villages around Etna covered by an ash-mantle 

and almost daily cleared. 

During this period, the most relevant air 

accident occurred on April 2000 when a 

commercial airplane (Airbus 320) departing 

from Catania airport encountered Etna’s ash 

cloud damaging cockpit windshields. 

During the last flank eruptions, occurred in 

2001 and 2002-03, an exceptional and 

prolonged explosive activity originated from 

vents opened on the upper slopes of Etna was 

observed for the first time in the last century 

(INGV Research Staff, 2001; Andronico et al., 

2004). Lava fountaining activity formed an ash 

plume 1-3 km high above the 2800 m vent (Fig. 

3), causing a continuous tephra fallout for 

almost two months during the 2002-03 eruption. 

Fig. 3: 2002-03 eruption ash plume dispersed 

eastward from the 2800 m vent in the S slope of 

Etna (Photo UFVG-INGV Sezione di Catania). 

Copious lapilli and ash covered the volcano 

slopes and fine particles reached Rome and 

central Italy, western cost of Greece at and the 

northern coast of Libya. Because the effects of 

this unusual flank activity have been very 

serious on both health and economy, 

particularly for the respiratory diseases widely 

reported, and for the frequent disruption of the 

flight operations at Catania and Reggio Calabria 

airports, the explosive activity of Etna has 

started to draw the attention of local 

administrators and national politicians (Fig. 4). 

Fig. 4: 2002-03 eruption plume and ash fall on 

Catania airport (Photo UFVG-INGV Sezione di 

Catania). 

The critical revision of the historical reports 

from the last four centuries (Branca and Del 

Carlo, 2004b) shows that eruptions 

characterised by long-lasting explosive activity, 

such as the 2001 and 2002-03, are not so 

unusual. The report by abbot Recupero (1985) 

describes a copious tephra fallout of 4 kg per 

square meter in Catania in about ten days during 

the La Montagnola eruption in 1763, whereas 

during the 2002-03 eruption, we measured 2.5 

kg per square meter in two days. In the 19th

century, the occurrence of this type of eruption 

is more frequent. Eruptions occurred in 1811, 

1852, 1886 and 1892 caused abundant ash 

fallout in the distal areas of the volcano. 

Therefore, the eruptive behaviour of Etna 

during the 2001 and 2002-03 eruptions is not a 

frequent phenomenon, yet at the same time it 

does not represent any anomaly in the eruptive 

history over the past centuries. 

The thick volcaniclastic successions, that 

blanket the eastern slope of the Etna edifice, 

record a history of important explosive activity 

in Late Pleistocene and Holocene times 

characterised by plinian, phreatoplinian and 

subplinian central eruptions and violent 

strombolian lateral eruptions (Coltelli et al., 

1998; 2000; Del Carlo et al., 2004). 

The discovery of these explosive eruptions 

raises important issues for hazard assessment of 

basaltic volcanoes in almost persistent activity 

such as Etna, indicating that even a volcano, 

commonly considered non-hazardous for 

humans, can become very dangerous for 

aviation safety. 

In summary, Etna’s explosive eruptions 

observed and quantitatively described, 

historically reported and stratigraphically 
Session 2 – Page 19 

studied, represent a severe threat for aviation 

and economy of Sicily. 

INGV staff in Catania, is in charged of the 

monitoring of the eruptive activity of Sicilian 

volcanoes, in response to this source of hazard, 

up to a few years ago completely ignored. It 

worked with Catania International Airport 

Direction, Italian Agency for Civil Aviation 

(ENAC), Meteorological Office of Italian Air 

Force and Italian National Civil Protection for 

warnings continuously the aviation authorities 

about the incidence of ash clouds on Sicilian 

airspace and the ash fallout on Catania airport 

depending on the intensity of the eruptive plume 

and the wind direction. With this aim, INGV is 

organizing an articulate strategy for studying in 

depth these eruptions, for setting an 

instrumental network to observe ash-cloud 

formation and developing, and finally for 

forecasting by mean of simulating computer 

models the ash dispersion in atmosphere and its 

fallout on the ground. 

The lesson learned during the 2001 and 2002-03 

crises was used to improve our volcanic ash 

cloud monitoring system, and transferred to 

ENAC for editing an official procedure for airtraffic and airport operations management in 

case of future crises at Etna, and in any case, to 

have a broad applicability worldwide. 

References 

Andronico D, Branca S, Calvari S, Burton MR, 

Caltabiano T, Corsaro RA, Del Carlo P, Garfì 

G, Lodato L, Miraglia L, Muré F, Neri M, 

Pecora E, Pompilio M, Salerno G, Spampinato 

L (2004) A multi-disciplinary study of the 

2002-03 Etna eruption: insights for a complex 

plumbing system. Bull Volcanol, DOI: 

10.1007/s00445-004-0372-8 

Branca S, Del Carlo P (2004a) Eruptions of Mt 

Etna during the past 3,200 Years: a revised 

compilation integrating the historical and 

stratigraphic records. In: Bonaccorso A, Calvari 

S, Coltelli M, Del Negro C, Falsaperla S (eds) 

Mt Etna Volcano Laboratory. AGU 

Geophysical monograph series 143, 1-27 

Branca S, Del Carlo P (2004b) Types of 

eruptions of Etna Volcano AD 1670-2003: 

Implications for short-term eruptive behavior. 

Bull. Volcanol., in press 

Coltelli M, Del Carlo P, Vezzoli L (1998) The 

discovery of a Plinian basaltic eruption of 

Roman age at Etna volcano (Italy). Geology, 

26:1095-1098 

Coltelli M, Del Carlo P, Vezzoli L (2000) 

Stratigraphic constrains for explosive activity 

for the past 100 ka at Etna volcano, Italy. Int. J. 

Earth Sciences, 89:665-677 

Del Carlo P, Vezzoli L, Coltelli M (2004) Last 

100 ka tephrostratigraphic record of Mount 

Etna. In: Bonaccorso A, Calvari S, Coltelli M, 

Del Negro C, Falsaperla S (eds) Mt Etna: 

Volcano Laboratory. AGU Geophysical 

monograph series 143, 77-89 

INGV Research Staff Sezione di Catania (2001) 

Multidisciplinary Approach Yields Insight into 

Mt Etna 2001 Eruption. EOS Transactions, 

American Geophysical Union 82:653-656 

Recupero G (1815) Storia naturale e generale 

dell’Etna. Ed. Dafni, Tringali Editore, Catania, 

1970 
2.6 

Session 2 – Page 21 

RECENT ERUPTIVE ACTIVITY IN ECUADORIAN VOLCANOES AND ITS THREAT TO 

AVIATION SAFETY 

Hugo Yepes A., Instituto Geofísico, Escuela Politécnica Nacional, Quito-ECUADOR 

hyepes@igepn.edu.ec 

Recently, Ecuadorian volcanoes have been unusually active. They are huge, tall volcanoes whose 

edifices rise more than 15.000 ft asl, therefore their eruptions start close to the flight corridors 

used by local commercial airlines. Guagua Pichincha (GGP) and Reventador (REV) have 

produced short lived but powerful eruptions (VEI ≥ 3), which generated superbuoyant eruptive 

columns and stratospheric injections of volcanic material. A distinctive characteristic is that 

these eruptive columns split at about the tropopause due to a 180o change in wind direction at the 

equatorial regions. This creates a virtual E-W ash shade for commercial routes flying N-S along 

the pacific coast of South America. Tungurahua (TUNG) is generating thermals since 1999 

within two altitude ranges: 1) quiescent plumes related to weak strombolian activity and/or 

permanent gas emissions that are being propagated by prevailing westerly winds between 

15.000-20.000 ft; and 2) stronger strombolian or vulcanian explosions which have been tracked 

by satellites to altitude levels higher than 25.000 ft. Sangay (SANG) sent its most recent ash 

cloud, 50 km long and traveling East at 18.000 ft, at the beginning of 2004. Thanks to the 

geophysical monitoring of the volcanic activity, the onset of the eruption period at GGP and 

TUNG was anticipated by the IG and transmitted to the responsible authorities, including 

commercial aviation (DAC). Once that eruption activity was correlated with seismic signals, it 

was possible to inform DAC about expected ash clouds or thermals beforehand. In some cases, 

especially during TUNG’s open system venting, no seismic signals are generated and 

information flows in opposite direction: from ground observers and pilots to the IG through 

DAC. REV’s eruption was sudden but the working relationship already established between IG 

and Washington VAAC greatly helped to establish the size and potential threat during early 

stages of the eruption. SANG is not monitored by the IG due to its remote location, but it poses a 

major threat to Guayaquil Airport and commercial routes. 
2.7 

Session 2 – Page 23 

THE ALASKA VOLCANO OBSERVATORY - FIFTEEN YEARS OF WORKING TO 

MITIGATE THE RISK TO AVIATION FROM VOLCANIC ASH IN THE NORTH PACIFIC 

Thomas L. Murray, Alaska Volcano Observatory, U.S. Geological Survey, 

Anchorage AK, USA 

On December 15, 1989, a passenger wide-body jet encountered an ash cloud erupted from 

Alaska's Redoubt Volcano. All four engines of the aircraft ceased operation and it descended 

almost 15,000 feet before the engines were restarted, enabling the aircraft to land safely in 

Anchorage. This near disaster was a defining moment for the then year-old Alaska Volcano 

Observatory (AVO). Almost all of Alaska’s volcanoes lie along the 1500-mile-long Aleutian 

volcanic arc which parallels the busy North Pacific air routes between North America and Asia. 

Generally, the main threat to life and property posed by explosive eruptions of Aleutian arc 

volcanoes is to aircraft. Thus, most of AVO's efforts have focused on limiting the risk to aviation 

in the North Pacific from volcanic ash, including (1)installing new seismic monitoring networks 

on remote volcanoes along the Aleutian arc to provide advanced notification of volcanic activity, 

(2)expanding the satellite remote sensing capability of AVO and developing this into an integral 

part of volcano monitoring and research, (3) undertaking geologic studies of Alaskan volcanoes 

to determine their eruptive histories and hazards, (4) working with other Federal and State 

agencies in Alaska to establish protocols and procedures that enable AVO to quickly notify the 

aviation industry of volcanic activity and volcanic ash clouds,(5) coupling the monitoring efforts 

with a strong research program to better understand volcanic processes in order to provide better 

forecasts of volcanic activity, and (6) working with Russian scientists to establish the 

Kamchatkan Volcanic Eruptions Response Team (KVERT)in order to insure reports of volcanic 

activity in Kamchatka are broadly distributed. 
2.8 

Session 2 – Page 25 

 GROUND-BASED REAL TIME MONITORING OF ERUPTION CLOUDS IN THE 

WESTERN PACIFIC 

Kisei Kinoshita1, Satoshi Tsuchida1, Chikara Kanagaki1, Andrew C. Tupper2, Ernesto G. Corpuz3 and Eduardo P. Laguerta3

1

 Faculty of Education, Kagoshima University, Kagoshima, Japan 

2

 Darwin Volcanic Ash Advisory Centre, Bureau of Meteorology, Northern Territory, Australia 

3

 Philippine Institute of Volcanology & Seismology, Quezon City, Philippines 

Abstract: Ground-based observation of eruption clouds, 

combined with satellite imagery, is very important for 

understanding their properties under various volcanic and 

meteorological conditions. Real time monitoring 

contributes greatly to aviation safety, since height 

information is essential for dispersion model prediction. 

The near-infrared camera serves to improve the 

observation because it is less sensitive to atmospheric haze 

and able to detect hot anomalies. We report here the 

monitoring of eruption clouds at Mayon volcano in the 

Philippines, and Suwanosejima, Satsuma-Iojima and 

Sakurajima volcanoes in southwest Japan. We also discuss 

volcanic clouds and gas at Miyakejima near Tokyo. 

 

1. Introduction 

 Volcanic clouds are often obscured on satellite 

imagery by meteorological cloud, or are too small-scale to 

detect. For aviation safety, a ground-based observation 

network is very useful for detecting ash ejections, and 

obtaining the vertical structure of the clouds. The flow and 

dispersion of volcanic clouds can be clarified by combined 

studies of ground observation and satellite images. Here 

we report our works in this direction concerning volcanoes 

in Japan and the Philippines. More details are described in 

the papers in a booklet of Kagoshima group [1]. 

2. Methods of ground-based observation 

2-1. Near-infrared and visible observations

 The near-infrared (NIR) band is widely used in 

satellite imagery, as it has quite different properties of 

surface reflection and atmospheric transportation 

compared with visible bands. The use of visible-cut filter 

in the cameras with CCD or CMOS sensor enables us to 

get NIR images in ground-based observation [2]. We are 

using a film type filter IR-84, which shields the light with 

wavelength < 840 nm. There are the following advantages 

for NIR over conventional visible observations, though the 

colour information is lacking: (i) The images are not so 

obscured by haze and mist. (ii) They may distinguish 

aerosols more clearly than visible images. (iii) They may 

detect very hot anomalies. (iv) They may detect vegetation 

damage by ash, gas and lava. 

Fig. 1 shows a comparison of NIR and visible 

images of Takachiho peak at Kirishima volcanoes 48 km 

away. We may see topographic features owing to the 

shading in NIR image, while we only see the outline of the 

mountain in visible image. 

Fig. 1. Takachiho peak in Kirishima volcanoes observed from 48 

km away in Kagoshima City on 14 Jan. 2004. (a) NIR image with 

IR-84 and ND400 filters in night-shot mode of SONY 

DCR-TRV30. (b) Conventional visible image. 

2-2. Methods of automatic recording and monitoring

 Since the features of volcanic clouds change 

with day and time, long period recording is necessary. 

Time-lapse recordings may be appropriate for the 

phenomena, except for very quick ones such as lightning. 

For this purpose, there are basically two alternatives [2] as 

follows. 
Session 2 – Page 26 

(A) Long-time automatic camera recordings: Video 

camera recording for 100 days is possible in a two hour 

videocassette by recording 0.5 sec. with 10 min. interval. 

Memories with large capacity are able to store quite large 

number of digital camera photos for a few to several 

months with an hourly interval. 

(B) Camera-computer system for monitoring and 

archiving: A web-camera with a personal computer or a 

network-camera alone is able to serve as a real time 

monitor accessible remotely via an Internet connection. 

For time-lapse recording and archiving, a server with 

enough storage capacity is necessary in the system. 

For both (A) and (B), a stable electric power 

supply is essential, and an uninterrupted power supply 

(UPS) must be used. 

3. Mayon volcano 

 After the gigantic Pinatubo eruption in 1991, 

Mt. Mayon (2462 m) near Legaspi in southeast Luzon has 

been the most active volcano in the Philippines (Fig. 2). It 

erupted in 1993 and 1999-2001 with pyroclastic and lava 

flows, as seen by the lack of vegetation in Fig. 3. In the 

latter eruptions, the appearance of hot lava in nighttime 

was detected by a video camera by using night-shot mode. 

Fig. 2. Location of Mayon volcano. 

Fig. 3. NIR image of Mayon volcano observed from 

Legaspi airport 11.5 km south from the summit. 

3-1. Interval recordings with visible-spectrum cameras

 Automatic interval recording at Mt. Mayon 

began on 22 June 2003 as joint work of the Philippine 

Institute of Volcanology and Seismology(PHIVOLCS) and 

the Kagoshima group. Digital and video cameras were set in 

an observatory on Lignon Hill situated at 11 km SSE of the 

summit crater. Fig. 4 exhibits a few video scenes of the 

plume flow, which depends on the wind around the summit 

height. From the records for eight months, it was found that 

cloud-free scenes are generally limited to morning and 

evening, as clouds develop to cover the summit during 

sunny days, following the tropical diurnal mesoscale 

convection cycle. This indicates the difficulty of satellite 

monitoring of volcanic eruptions in the moist tropical areas. 

Fig. 4. Typical scenes of the plumes at Mayon volcano. 

(a) Horizontal flow for fresh wind, 

(b) Rise and flow under mild wind. 

3-2. Network camera system to take NIR and visible images

 On 24 February 2004, we installed a network 

camera system that has NIR and visible cameras in 

parallel, as shown in Fig. 5, except for the Internet 

connection. 

Fig. 5. Network camera system. 
Session 2 – Page 27 

 The system started to operate as a local 

network, to store visible images every ten minutes during 

5:30 and 18:30, and near-infrared images every one-hour 

continuously in a network-attached storage (NAS). 

Since April 2004, the network camera system 

is connected with the Internet, and real time access is 

possible from Quezon and Kagoshima. It should be noted, 

however, that the Internet is often disconnected by the 

shutdown of a server in the route whenever there are 

thunderstorms to avoid power surges and spikes. We are 

planning to construct a semi-real time homepage for 

worldwide access. A preliminary report of volcanic cloud 

observation at Mt. Mayon is given in [3]. 

4. Island volcanoes in southwest Japan 

 There is a chain of island volcanoes in the 

Nansei Islands in southwest Japan (Fig. 6). Among them, 

Suwanosejima volcano is the most eruptive in Japan in 

these years, while Satsuma-Iojima volcano is continuously 

ejecting plumes for many years. 

Fig. 6. Location of Suwanosejima and Satsuma-Iojima. 

Three small islands in between them are also volcanic islands. 

4-1. Suwanosejima 

 There were many eruptions of Strombolian 

and Vulcanian types from the summit crater (799 m) at 

Suwanosejima in the last century. The volcano was 

rather dormant for five years since 1995, and resumed 

eruptions since the end of 2000. Eruption clouds at 

Suwanosejima are hazardous for low level (4-5 km) 

aviation, and the emitted ash frequently affects other 

populated islands in the vicinity. As it was difficult to have 

a good observation station on the island, we set a network 

camera at Nakanoshima, 25 km to the northeast, and 

connected it with the Internet on 6 August 2002.

 Suwanosejima was especially active in 2002, 

erupting many times almost every day in August, and with 

72 eruptions on 5 December. Some of them were detected 

by NOAA/AVHRR, EOS/MODIS and GMS/VISSR 

images, and reported by pilots to Tokyo-VAAC. Most of 

them since August were seen in the monitoring records 

such as shown in Fig. 7, though many of them were 

somewhat obscured by sea-haze. A summary of ground 

and satellite observations in 2002 is described in [4]. 

Fig. 7. Suwanosejima eruption on 14 Aug. 2002 

Fig. 8. NIR monitoring camera image of Suwanosejima plume 

 on 29 April, 2004 at 12:00 JST. 

 On 18 February 2004, the monitoring camera 

at Nakanoshima was changed from a conventional visible 

type to NIR type in order to minimize the sea-haze 

obscuration and to detect hot anomalies. Improved results 

have been obtained in spite of the long distance over the 

sea, such as shown in Fig. 8. 
Session 2 – Page 28 

 At the points where AC power supply is not 

available in Suwanosejima, we tested the interval 

recording by using digital camera package with 

rechargeable battery pack in a sealed transparent box. 

Such a package may be useful in long-time field 

observation, as it is small, lightweight and relatively 

expendable. 

4-2. Satsuma-Iojima 

 Satsuma-Iojima (or Kikaijima) is a volcanic 

island at the NW rim of the Kikai caldera, most of which 

lies below the sea level formed about 7000 years ago. It 

has continued active ejection of gas mainly from the 

summit crater at Io-dake (703 m) for more than several 

hundred years. 

Long-time automatic recording of the volcanic 

cloud started in July 1998 at a station about 3 km WSW of 

the crater, under the support of Nittetsu Mining Co. Ltd. A 

digital camera for hourly interval such as shown in Fig. 9, 

and a video camera with 0.2 sec. recording with 3 min. 

interval were installed. The video recording has been 

changed into 0.5 sec. with 10 min. interval since September 

1999. In these modes, the automatic recordings are possible 

without changing media for about three months. 

Fig. 9. Digital camera records at Satsuma-Iojima on 22 Aug. 2002. 

Explosive eruptions affecting aviation have 

been rare at Io-dake in recent years. The ejection of 

volcanic plume was rather constant most of the time, with 

the height about 100-800 m above the summit depending 

on the winds. The highest heights in 2000-2002 were 

about1300-1500 m. Further discussions are given in [5]. 

 For real time monitoring and archiving, a web 

camera system was installed in February 2003, and the 

camera head has been turned into NIR type since 

December 2003. The video camera has been turned into 

NIR mode since July 2003. It was found that analog 

connection of the telephone line was troublesome for the 

web-camera system. The Japan Meteorological Agency 

(JMA), which is responsible for volcanic disaster 

prevention, installed a high sensitivity camera with 

satellite communication line in November 2002. JMA also 

installed similar system at Nakanoshima for 

Suwanosejima monitoring in March 2003. It is desirable 

that different systems and modes are running in remote 

island volcanoes to observe various aspects of volcanic 

clouds and backup each other. 

5. Sakurajima 

 Since 1972, Sakurajima volcano has been 

continuously active, ejecting ash plumes almost daily from 

the summit crater Minamidake (1040 m), mixed with 

Vulcanian and Strombolian eruptions occasionally. 

There had been many ash encounters of commercial 

aircrafts until 1991. The encounters have been quite 

reduced since then, by routing aircraft away from ash. 

 The Kagoshima group started interval 

recording of Sakurajima clouds in September 1987 at B in 

Fig. 10, 9.8 km WSW from the crater, and has published 

highlighted results on the Internet since 1997. Previous 

works of ground observations and satellite imagery of 

volcanic clouds are summarized in [6]. All of the 

archived records are now being converted into digital 

movies. Real time monitoring and archiving of the cloud 

images, accessible via the Internet, commenced at A in Fig. 

10 in December 2000, and also at Ta and C in February 

and March 2003. 

Fig. 10. The topography of Sakurajima and the surrounding 

Kagoshima Bay observed from southern sky (SiPSE 3D 

graphics). The gas monitoring stations (+), and camera 

monitoring points (A, B, C, Ta) are indicated. 
Session 2 – Page 29 

At the foot of the volcano around the crater, 

there are four stations monitoring surface concentration of 

SO2 and suspended particulate matter (SPM), as shown in 

Fig. 10, providing continuous measurement data with 

one-hour resolution since the 1980s. By comparing these 

data with the record of volcanic clouds and upper wind 

data, it was found that SO2 concentrations at the foot of the 

volcano are high only when the winds around the summit 

are strong enough to create a lee wave and blow the 

volcanic plumes and gases down to a measuring station [7]. 

6. Miyakejima 

 Since July 8, 2000, Miyakejima volcano, about 

160 km south of Tokyo (Fig. 11), has been very active, 

with a few big eruptions to disturb aviation in August 2000, 

and continuous ejection of enormous amount of poisonous 

gases since mid-August 2000, which compelled all of the 

inhabitants to evacuate from September 2000. The SO2

flux in the ejected gas monitored by airborne Correlation 

Spectrometer was a few 10000s of ton/day in late-2000, 

and decreased gradually: it is still 4000-10000 ton/day in 

2004. SO2 was detected 100-400 km leeward in the 

mainland of Japan. 

Fig. 11. Miyakejima and other Izu islands (NOAA/AVHRR 

image on 11 Dec. 2000, 13:25 JST). 

 The number of SO2 monitoring stations at the 

foot of the volcano increased from three in December 

2000 to fourteen in April 2004. The Kagoshima group 

analyzed the data, comparing with upper winds at 

Hachijojima, NOAA/AVHRR images and ground 

observation data from Mikurajima [8]. It was confirmed 

that, as in Sakurajima, fresh winds around the summit are 

responsible for the high concentration events at 

downstream stations [9]. The ground monitoring of the 

clouds is now performed by JMA at various points inside 

and outside the island. 

7. Concluding remarks 

 Long-time automatic observation by the 

cameras from the ground, combined with satellite images, 

is useful for the studies of volcanic clouds and gas. 

 The use of NIR band has opened a new era of 

the ground observation. 

 Real time monitoring from the ground is 

important for aviation safety, disaster prevention of 

inhabitants and avoidance of ash and gas damages far 

away. It is especially important in order to speculate the 

flow of poisonous gas from the crater. 

References 

[1] Kagoshima Univ. Group, Volcanic Eruption Clouds in 

the Western Pacific - Ground and satellite based 

observations and analyses -, 2004. 

[2] K. Kinoshita et al., Ground and Satellite Monitoring of 

Volcanic Aerosols in Visible and Infrared Bands, The 

CEReS Int. Symp. Remote Sensing, Chiba, Japan, Dec. 

2003, 187-196 (Paper I in [1]). 

[3] K. Kinoshita et al., Ground and satellite-based 

monitoring of Mayon Volcano, Philippines, paper III in [1]. 

http://arist.edu.kagoshima-u.ac.jp/volc/mayon/ 

[4] C. Kanagaki et al., Ground and Satellite Observation of 

Eruptions and Plumes at Suwanosejima, IUGG 2003 

Scientific Program, and Paper XI in [1]. 

[5] T. Matsui et al., Automatic long-time observation of 

the volcanic clouds at Satsuma-Iojima, paper X in [1]. 

[6] K. Kinoshita, Observation of Flow and Dispersion of 

Volcanic Clouds from Mt. Sakurajima, Atmos. Env. 30, 

2831-2837; 1996, K. Kinoshita (ed.), Flow and Dispersion 

of Volcanic Clouds, Kagoshima Univ., 2001. 

http://arist.edu.kagoshima-u.ac.jp/volc/index-e.html 

[7] K. Kinoshita et al., Ground observation of volcanic 

plumes and high SO2 concentrations at Sakurajima 

volcano, paper IX in [1]. 

[8] A. Terada, Y. Ida and T. Ohminato, Automatic Image Recording 

System Using the Windows PCs:Application to the Eruption 

Columns of Miyakejima Volcano, Japan, Kazan, 48, 445-459, 2003. 

[9] Papers V-VIII in [1]. 
P2.1 

Session 2 – Page 31 

ACOUSTIC SURVEILLANCE FOR HAZARDOUS ERUPTIONS (ASHE): 

A PROPOSAL FOR A PROOF-OF-CONCEPT EXPERIMENT 

McCormack1

, D, P. Chen2, M. Jean2, H. Bass3, M. Garces4

1

Geological Survey of Canada, 1 Observatory Crescent, Ottawa K1A 0Y3 Ontario, Canada. 

cormack@seismo.nrcan.gc.ca 

2

Canadian Meteorological Centre, 2121 North Service Road, Trans Canada Highway, Dorval, Quebec, H9P 1J3, 

Canada, Peter.Chen@ec.gc.ca, Michel.Jean@ec.gc.ca 

3

National Center for Physical Acoustics, University of Mississippi, University, MS 38677, pabass@olemiss.edu 

4

Infrasound Laboratory, University of Hawaii, Manoa, 73-4460 Queen Kaahumanu Hwy., #119, Kailua-Kona, HI 

96740-2638, milton@isla.hawaii.edu 

SUMMARY 

Ash injected into the atmosphere from volcanic 

eruptions poses a significant hazard to aircraft 

operations. In principle, infrasound monitoring 

will complement both seismic observation and 

satellite remote sensing to improve continuous 

monitoring of wide regions of potential eruption 

hazard at modest cost. This paper proposes an 

experiment to test both the practical utility of 

infrasound as a regional-scale volcanic eruption 

detection tool, and the feasibility of using such 

an infrasound system to contribute to the 

aviation industry timely operational alerts 

through Volcanic Ash Advisory Centres 

(VAACs). We propose a field deployment of 

several small prototype infrasound arrays in a 

suitably selected region, sending data in real 

time to a central data centre where algorithms 

for eruption detection may be prototyped. The 

results will be sent on a test basis to participating 

VAACs for comparison with the performance of 

existing warning systems. 

Introduction 

More than 80 separate incidents of interaction 

between aircraft and ash have been reported over 

the last twenty years. Incidents on international 

flight paths over remote areas have resulted in 

engine failures and significant damage and 

expense to commercial airlines. In order to 

protect aviation from volcanic ash, pilots need 

rapid and reliable notification of ash-generating 

events. Systems need to produce a minimum of 

false alarms to reduce additional fuel costs and 

delays from re-routings. 

Whilst many volcanoes, particularly near population 

centres or in developed countries, are instrumented 

directly with cameras, microphones, strain and 

deformation meters, seismometers, etc.1

, there 

remain large portions of the earth’s surface, 

particularly in remote areas or less-developed 

countries, where local ground-based surveillance 

systems are sparse or non-existent. Despite their 

remoteness, some of these areas lie under major 

intercontinental air routes. To instrument all known 

volcanoes with on-site sensors would be extremely 

expensive, both in terms of hardware and ongoing 

operational costs, and consequently attention is 

focused on using remote-sensing systems of various 

types to monitor broad areas in a cost-effective 

fashion. 

Existing Broad-Area Monitoring Systems 

Much research has gone into use of Earth 

observation satellites both for eruption detection and 

tracking of ash once injected into the atmosphere. 

Although multispectral techniques have had some 

impressive successes, timeliness is limited by the 

sampling interval of appropriate satellite images, and 

weaknesses remain in the ability to robustly identify 

ash in the presence of intervening cloud or when 

there is ice entrained in the ash.2

Since many volcanoes are in tectonically active 

regions where earthquakes are frequent, there are 

often regional seismic networks already in place. 

However, volcano-associated seismic signals are 

often of low magnitude and are difficult to detect 

reliably at distances of hundreds of kilometres, 

requiring a high density of seismometers near the 

volcanoes. Additionally, there is no exact 

correspondence between seismic and eruptive 
Session 2 – Page 32 

activity, resulting in possible high false alarm 

rates from regional seismic monitoring. 

Acoustic surveillance can reduce the ambiguity 

between eruptive and purely seismic activity in 

an active volcano and provide additional (and 

possibly more precise) estimates for the onset 

time of an eruption. 

Use of Infrasound 

The potential of using low frequency sound, or 

infrasound, to rapidly identify explosive 

volcanic eruptions has been discussed in the 

environmental acoustics and aviation safety 

communities for some time3,4. A direct link 

between the excitation of acoustic signals and 

the pressurized injection of ash into the 

atmosphere during an eruption has been 

demonstrated by over a century of observation5

. 

The ability of sounds in the frequency range 

from 0.01-10 Hz to propagate for long distances 

in the atmosphere with little attenuation would 

suggest broad-area regional monitoring with a 

modest number of observing sites should be 

possible. However, progress on a demonstration 

of the concept has been slow, hampered by 

uncertainty as to the operational feasibility of the 

technique, lack of experience running infrasound 

systems for prolonged periods in remote areas, 

difficulties with data access, and a general lack 

of support for infrasound science. 

Largely driven by the infrasound requirements 

of the Comprehensive Nuclear Test Ban Treaty 

(CTBT) International Monitoring System (IMS), 

significant practical experience has now been 

gained in the operation of autonomous 

infrasound systems in a wide range of 

environments from tropical jungles to polar ice 

sheets. In addition, low powered satellite 

communications systems are now available 

which make it feasible to install real-time 

communications links between data centres and 

remote operating locations far from civil 

infrastructure. Consequently, it seems an 

appropriate time to revisit the idea of using 

infrasound for remote volcano monitoring. 

Although there is progress in resolving existing 

policies that restrict access to IMS data for civil 

applications6

, in practical terms the IMS network 

is not optimized for a volcanic monitoring role. The 

requirement that a 60 station infrasound network 

cover the globe yields stations thousands of 

kilometres apart with few close to areas of concern 

to the aviation community. Consequently, and for 

operational reasons, we propose deploying new 

infrasound arrays for the experiment, tailored for the 

task and free of any restrictions on data distribution. 

Experimental Design 

The first objective of the experiment is to test that 

infrasound is a practical tool for detection of ashgenerating eruptions. We propose to identify a 

region with a number of active, well-monitored 

volcanoes, and deploy at least two infrasound arrays. 

The arrays would telemeter data in real-time to an 

appropriate central location where we could test 

various detection and identification schemes. We 

would seek to record and identify acoustic signals 

from an azimuth corresponding to a known 

candidate source, and ideally determine signal 

characteristics that would suggest a volcanic origin. 

Initial calculations suggest that arrays with four 

sensors and an aperture of 200-300 metres provide 

adequate azimuthal resolution over distances of 

several hundred kilometres. Comparison of results 

with on-site volcano monitoring technologies would 

provide ground-truth validation of results. 

Although demonstrating reliable infrasound 

detection of an eruption is critical, an operational 

alert system also requires that the information be 

relayed rapidly to aircraft in the vicinity. Clearly, the 

closer one can install instruments to a source, the 

larger the signal7

, and the sooner it arrives. 

However, this must be balanced against the need to 

cover large areas from a reasonable number of 

discrete observing locations. Initial discussions with 

the FAA noted that while users have stated a 

requirement to receive notification of an eruption 

within 5 minutes of an eruption for an alert of 

airborne ash, it was felt that an alert issued within 

approximately 15 minutes of the time of eruption 

would be of significant benefit, particularly in 

remote and unmonitored regions of the world.8

 The 

International Civil Aviation Organization (ICAO) 

has designated a number of meteorological centres 

as regional Volcanic Ash Advisory Centres 

(VAACs) which are charged with the responsibility 

of issuing so-called Volcanic Ash Advisories to the 
Session 2 – Page 33 

aviation community, based on a synthesis of 

available information from pilots’ reports, 

satellite observations, local observatories, etc. 

We propose to use one or more VAACs as 

recipients of the output of the prototype 

infrasound system. Feedback on comparisons of 

the system performance versus existing 

surveillance systems will provide additional 

feedback on system feasibility. 

Conclusion and Next Steps 

Recent developments in infrasound technology 

and expertise, automatic data processing, and 

satellite communications technology suggest 

that this is an opportune moment to revisit the 

concept of acoustic surveillance for detections 

and alerting of hazardous eruptions. A projected 

increase in the confidence and timeliness of an 

alert would help protect aircraft from the effects 

of ash. The next step is to identify a suitable 

partner organization in a country with active 

volcanoes that can provide technical and 

logistical assistance for a deployment of 

sufficient duration to evaluate the concepts 

presented in this paper. 

 

1

 See http://www.cenapred.unam.mx/mvolcan.html 

for an interesting example. 

2

 Tupper, A., S. Carn, J. Davey, Y. Kamada, R. Potts, 

F. Prata, and M. Tokuno, 2004: An evaluation of 

volcanic cloud detection techniques during recent 

significant eruptions in the western 'Ring of Fire'. 

Remote Sensing of Environment, in press. 

3

 Chen, P. and D.R. Christie, 1995: Infrasound 

Detection of Volcanic Explosions by the CTBT 

International Monitoring System: Implications for 

Aviation Safety. Information paper, 2nd Meeting of 

the ICAO Volcanic Ash Warning Study Group, 2 

November 1995, Montreal Canada, 5pp. 

4

 Kamo, Kosuke, K. Ishihara, and M. Tahira, 1994, 

Infrasonic and Seismic detection of explosive 

eruptions at Sakurajima Volcano, Japan, and the 

PEGASAS-VE early-warning system. Proceedings of 

the First International Symposium on Volcanic Ash 

and Aviation Safety, USGS Bulletin 2047, 357-365. 

5

 Strachey, R., 1888. On the air waves and sounds 

caused by the eruption of Krakotoa in August, 1883, 

in The Eruption of Krakatoa and Subsequent 

Phenomenoa, pp. 57-88, Trubner, London. 

 

6

 See http://www.wmo.ch/web/www/DPS/DPFS-ERAUS/ ERA-COG-Doc8(2)-F.pdf for additional information. 7

 We are neglecting here complexities introduced by 

atmospheric structure. Precise locations for the 

experiment will be chosen after detailed modelling of 

signal propagation. 

8

 This timeframe defines a scale for the distances of the 

infrasound arrays from the source, considering the 

acoustic propagation velocity. 
P2.2 

Session 2 – Page 35 

RECURRENCE OF EXPLOSIVE ERUPTIONS AT ETNA VOLCANO THAT 

PRODUCE HAZARD FOR AVIATION 

Paola Del Carlo, INGV, Catania, Italy 

Mauro Coltelli, INGV, Catania, Italy 

The recent activity of Etna is characterised by the occurrence of a large number of 

explosive eruptions, many of which have produced eruptive plume and copious ash 

fallout on its flanks. Since 1989 Etna summit craters have produced more than 150 fire 

fountain episodes, characterized by: i) eruptive columns from 2 to 12 km high above the 

vent, ii) tephra volumes ranging from 104

 to 107 m3 and iii) magnitude from violent 

strombolian to subplinian. Furthermore, in 2001 and 2002 flank eruptions, a prolonged 

explosive activity, forming a 1-4 km high ash column, caused continuous tephra fallout 

for several weeks. Lapilli and ash blanketed the volcano slopes and fine particles 

reached hundreds of km of distance. The effects have been very serious on both 

economy and health, particularly for the disruption of the operations of Catania and 

Reggio Calabria airports. Widening the temporal interval to the last 3 centuries, the 

historical record documents other five flank eruptions, comparable to the 2001 and 2002, 

that produced copious tephra fallout up to Malta Island and Calabria region. 

Furthermore, from the 18th century onwards, summit activity was characterised by 

several episodes of fire fountain and some short-lived sub-plinian episodes (on average 

two per century) that caused ash fallout on the eastern Sicily. Therefore, the eruptive 

behaviour of Etna observed in the last fifteen years does not represent any anomaly in 

the activity over the past three centuries. Nonetheless, the historical record analysis 

indicates an increase of the frequency of ash-plume forming eruptions from 1880 and 

again from 1961, highlighting Etna as certain source of risk for aviation in central 

Mediterranean region. 
P2.3 

Session 2 – Page 37 

A PROPOSED ALERT-LEVEL NOTIFICATION SCHEME FOR AVIATION AND 

GROUND-BASED HAZARDS AT U.S. VOLCANOES 

C.A. Gardner, USGS Cascades Volcano Observatory, Vancouver, WA 98683 USA, cgardner@usgs.gov

Marianne Guffanti, USGS National Center, Reston, VA 20192 USA 

C.C. Helicker, USGS Hawaiian Volcano Observatory, Hawai’i Volcanoes National Park, HI 96718 USA 

D.P. Hill, USGS Long Valley Observatory, Menlo Park CA 94025 USA 

J.B. Lowenstern, USGS Yellowstone Volcano Observatories, Menlo Park CA 94025 USA

T.L. Murray, USGS Alaska Volcano Observatory, Anchorage, AK 99508 USA 

Introduction

The function of hazard notification schemes 

is to give public officials and the public warning 

about the proximity of a hazardous event (Scott, 

this volume). How precise these warnings can be 

depends upon the nature of the hazardous event. 

Prior to eruptions, volcanoes exhibit precursory 

behavior over a period of days to years, such 

that notices of impending eruptions can usually 

be made far enough in advance for affected 

groups to take mitigative action. But, volcanoes 

do not erupt with consistent precursors or in a 

uniform style; nor do all episodes of unrest end 

in eruption. Thus there is considerable 

uncertainty in assessing future volcanic behavior 

at restless volcanoes. These uncertainties affect 

the precision of volcano notification schemes 

and provide a challenge in developing them. 

In this paper, we discuss a proposed alertlevel notification scheme for activity at U.S. 

volcanoes monitored by the U.S. Geological 

Survey’s Volcano Hazards Program (USGSVHP). We discuss the motivation and goals of 

the scheme, the rationale for the different levels, 

and how it is incorporated into the USGS-VHP’s 

overall mitigation strategy to inform the public 

about potential volcanic eruptions. 

Proposed Notification Scheme

The U.S. and its territories have 

approximately 170 volcanoes that have erupted 

over the past 10,000 years, 80 of which have had 

one or more eruptions in historical time (past 

250 years). Of the 80 historically active 

volcanoes, about 50 are monitored at varying 

levels of thoroughness. Some of these 

volcanoes are near major cities, whereas others 

are in remote areas hundreds to thousands of 

kilometers away from ground-based populations. 

Under Federal law, the USGS has the 

responsibility to monitor U.S. volcanoes and provide 

timely warnings to public officials and affected 

communities. The USGS-VHP currently has five 

volcano observatories and provides assistance to the 

Commonwealth of the Northern Mariana Islands. 

Three of the five observatories have developed alertlevel notification schemes in order to meet the needs 

of nearby populations and the aviation community. 

Although there are similarities among the three 

schemes, they are not identical. To minimize 

confusion from multiple schemes in the future, 

especially if there are simultaneous eruptions being 

handled by different observatories, and to avoid reinventing schemes by observatories currently 

without one, a single system is explored. 

The goal is to design a single system that (1) can 

accommodate a range of styles, sizes, and durations 

of volcanic activity (both precursory and eruptive); 

(2) will work during escalating and de-escalating 

activity; (3) is useful to both ground-based 

communities and the aviation sector; (4) does not 

disrupt currently effective communication between 

the observatories and their partners; and (5) is 

scientifically defensible. 

These are not trivial requirements. Typical 

volcanic eruptions can vary in style from relatively 

passive events to extremely explosive ones and in 

size (volume of erupted material) from 0.001 km3

 to, 

rarely, >100 km3

. Generally, an eruption involves 

episodes of eruptive activity separated by noneruptive intervals of hours to months. The duration 

of a single eruptive episode usually ranges from a 

few minutes to tens of hours, whereas the entire 

eruption can last for a day to many decades 

(Simpkin and Siebert, 1994; Wunderman et al., this 

volume). As a result, an observatory may need to 

change alert levels numerous times over the course 

of a volcanic eruption. Similarly, during unrest, 

volcanoes exhibit a wide range in precursory styles 
Session 2 – Page 38 

and durations. There may be several cycles of 

increasing and decreasing unrest, before or after 

an eruptive episode, or before it is clear no 

eruption will occur. Again, it is important that 

notification systems can accommodate the upand-down pattern of many volcanic crises. 

Some eruptions affect only ground-based 

communities and others only the aviation sector, 

but explosive eruptions at volcanoes that are 

near major communities, or that are large 

enough that the ash falls on populated areas, will 

affect both. Lastly, although there are many 

challenges in eruption forecasting (see Newhall, 

this volume), an alert system must be 

scientifically defensible to be consistently 

applied. 

The scheme proposed here (Fig. 1) has four 

levels, each assigned a color (Green, Yellow, 

Orange, Red), based on a modified stop-light 

configuration and the aviation color-code system 

developed by the Alaska Volcano Observatory 

(AVO) and recommended by the International 

Civil Aviation Organization (ICAO). The 

scheme also includes hazard terms that are used 

by the National Weather Service (NWS) and 

familiar to most ground-based emergency 

management personnel. The dual system of 

colors and terms allows the aviation and 

emergency management communities to use the 

terminology that best suits them, but only a 

single alert-level would be issued (e.g., 

Yellow/Advisory) at any time. The descriptions 

reflect activity at the volcano and can be used 

during escalation and de-escalation. The 

descriptions are general to allow for the variety 

of volcanic unrest and eruption and to give 

observatories the flexibility to expand the 

definitions or, if necessary, to subdivide alert 

levels in order to meet the needs of user groups. 

Any modifications, however, should reflect the 

overall intention of the levels as discussed in the 

following paragraphs. 

GREEN/NORMAL is the typical noneruptive state of a volcano. This level allows for 

periods of increased steaming, seismic events, 

deformation, thermal anomalies, or degassing, as 

long as the activity is within the range seen at 

the volcano during its monitoring history, or at 

similar types of volcanoes. One difficulty is 

how to interpret data from new monitoring 

techniques, such as InSAR, because there may 

be no comparable data to use as a baseline. Another 

nuance of this level is that unrest initially seen as 

“anomalous” -- such as the increased steam and 

thermal output at Mount Baker volcano in 1975, or 

some of the periods of elevated unrest at Long 

Valley caldera through the 1980s and 1990s -- may, 

after some time, become considered normal 

background or regional activity. 

Figure 1. Proposed unified alert-level notification 

scheme for volcanic activity 

Color Term Description 

GREEN NORMAL 

Normal non-eruptive state; typical 

background activity 

YELLOW ADVISORY

Elevated unrest above known 

background activity 

ORANGE WATCH 

Escalating or sustained unrest 

indicates eruption likely, 

timeframe variable. OR, eruption 

underway that poses a localized 

hazard 

RED WARNING 

Hazardous eruption is underway 

OR expected within hours 

YELLOW/ADVISORY signifies that one or more 

monitoring parameters are outside the “normal” 

range of activity. This level implies that what drives 

the unrest may be magmatic in origin and could be 

precursory to an eruption, but that we expect to see 

much higher levels of unrest before an eruption 

begins. At this level, there is a strong possibility 

that no eruption will occur. Stating precisely when 

unrest is above “normal” is often difficult, especially 

when unrest begins gradually. During de-escalation, 

the definition is the same as during escalation and 

implies that monitoring parameters have not yet 

returned to baseline levels. 

ORANGE/WATCH means either that (1) 

sustained high levels of unrest of one or more 

monitoring parameters are well outside the “normal” 

range or, (2) an eruption is in progress but poses 

only a localized hazard (i.e., no communities, major 

airports, or overflight paths). The rationale for this 

dual nature primarily is the need to distinguish 

between hazardous eruptions and those that do not 

pose a significant hazard to life or property. For 

example, lava flows from Kilauea Volcano, Hawai’i 

are currently flowing through Hawai’i Volcanoes 
Session 2 – Page 39 

National Park, but they are not a threat to homes 

or important Park structures. Using our proposed 

scheme, we would consider the alert level as 

Orange/Watch. If the lava were to start flowing 

through communities and threatening homes and 

businesses (as it has done in the past), then the 

alert level would be raised to Red/Warning. 

Another example of a non-threatening 

eruption is dome growth at a remote volcano 

(e.g., Bezymianny, Kamchatka). In this 

situation, however, dome collapse could quickly 

change the situation from being non-threatening 

to potentially hazardous for air traffic. In 

situations like dome growth/collapse and when 

escalating to or de-escalating (sustained unrest) 

from hazardous eruptions, Orange/Watch is a 

warning that the situation is dynamic and could 

(not will) change quickly. There is no specific 

time frame associated with this level, but during 

escalation it usually implies that an eruption is 

more likely and more imminent (but still not 

guaranteed) than when in Yellow/Advisory. 

We decided against using a fifth color to 

handle non-threatening eruptions because (1) 

there is no equivalent in the NWS terminology 

so there would be no familiar term for the 

ground-based communities, (2) it would be nonlinear as one wouldn’t necessarily escalate or deescalate through this color, (3) it would be nonintuitive (is color A more or less of a concern 

than color B?), and (4) we wanted to avoid 

confusion with the U.S. Department of 

Homeland Security’s five-tiered color code 

system. 

The proposed Orange/Watch definition is 

similar in intent to the AVO and ICAO color 

code ORANGE. Like those schemes, the 

proposed level has a dual nature of either high 

unrest or a largely non-hazardous eruption. It 

differs primarily in that it does not define an ash 

plume threshold. The ash plume altitude of 

25,000’ was conceived as a useful threshold of 

concern for the North Pacific Region where 

many volcanoes are remote but where ash 

plumes above 25,000’ can affect a large volume 

of air traffic at cruise altitudes. A concern with 

the 25,000’ threshold for all observatories is that 

in places where airports are close to volcanoes, 

ash plumes of less than 25,000’ can be very 

hazardous to the aviation industry. Thus we 

have tried to adhere to the intent and duality of 

the original ORANGE definition, but have deleted 

the specific altitude threshold so that it could be 

more widely applied. In some instances, 

observatories may want to assign an altitude or some 

other threshold to an alert level in order to highlight 

specific aviation or ground-based concerns. For 

example, at remote locations where there are no 

nearby populations or airports, an observatory may 

want to use an altitude, similar to that currently in 

use at AVO to define Orange/Watch. Even if no 

ash plume threshold is assigned, any available 

information regarding ash plume height should 

be part of all alert-level notices when in 

Orange/Watch or Red/Warning. 

RED/WARNING means that monitoring data are 

at levels that suggest a potentially hazardous 

eruption is underway or is expected in the near 

future (hours). This level does not indicate whether 

the eruption is small, moderate, or large, or who is at 

risk—aviation, ground -based communities, or 

both. Rather it indicates that the eruption either is, 

or potentially is, life threatening to one or both 

groups, and that action to mitigate the threat is 

needed or should have been completed already by 

those groups. An observatory may choose to have 

sublevels within Red/Warning for explosive 

volcanoes that have a large range in eruption size. 

Because volcanologists cannot reliably forecast 

eruption size, most observatories would likely raise 

the alert level to Red/Warning as soon as an eruption 

began for those volcanoes that have a history of at 

least some moderate explosive events (VEI ≥ 3; 

Newhall and Self 1992; Newhall this volume). 

Although some eruptions raised to Red/Warning 

may be better classified as Orange/Watch in 

hindsight, it may be better to be cautious than to 

mistake a hazardous event for a non-hazardous one. 

Volcanic events are unique enough that it is 

impossible to predetermine a detailed set of criteria 

for each level that would be applicable in all 

situations. The above definitions are guidelines for 

scientists to use to categorize the level of unrest, and 

for public officials and the public to consider when 

deciding what actions they need to take. Our 

scheme as portrayed in Figure 1 is a way to 

communicate quickly our scientific judgment about 

the level of unrest. For more detailed information, 

the USGS-VHP usually issues daily, or more often if 

needed, updates on the status of the volcano. These 

communications typically give the volcano’s 

location in latitude and longitude, height of the 
Session 2 – Page 40 

volcano’s summit, the alert level, a short 

synopsis of the monitoring data, interpretation of 

that data, and both a short- and long-term 

forecast of likely activity. These daily updates 

are essentially the scientific rationale for the 

alert level assigned. If the volcano erupts, 

information about when the eruption began, the 

presence or absence of a plume, plume height 

and volcanic phenomena that affect groundbased activities would be conveyed along with 

the change in alert level. 

In order for alert-notification systems to 

succeed, users must be aware the system exists, 

understand its strengths and weaknesses, and 

provide feedback when it works and when it 

fails. Communication is a critical element to 

mitigating any crisis. Effective communication 

includes two-way exchanges of information as 

events unfold and clear protocols for 

disseminating warnings when needed. 

Because volcanologists do not directly 

measure the rise of magma during volcanic 

unrest, and because not all volcanoes are 

monitored, visual observations are an important 

monitoring tool. Volcanologists are located in 

only a few places compared to the geographical 

distribution of volcanoes, so observations from 

pilots and individuals on the ground can be vital 

in detecting unrest and eruptive activity. For 

example, a pilot was the first to note the second 

eruption of Crater Peak, Alaska, on 18 August 

1992 and immediately informed the AVO of the 

event. At that time there was only a weak signal 

on the seismic records which would not have 

been interpreted as the beginning of an eruption 

(Eichelberger et al. 1995). It is critical that 

outside observers know how to contact 

observatories and that those observatories are 

receptive to outside observations in order for 

two-way exchanges of information to occur. 

Although two-way exchanges of information 

are important for monitoring unrest and activity, 

protocols are needed to ensure that essential 

information is communicated efficiently and that 

the source of the information can be quickly 

verified. Every year there are many false reports 

of eruptions and one can only imagine the 

disruptions they would cause if they were all 

acted upon. Protocols work best if they are 

already in place before a crisis begins and if they 

are practiced regularly. The USGS-VHP is 

working with emergency managers and aviation 

personnel to set up protocols in the event of volcanic 

unrest and eruption. Face-to-face interactions are 

one of the biggest benefits of such discussions, as it 

is often easier to communicate openly with someone 

you know than with a stranger. It is not always 

possible to develop protocols in advance, but when 

they are already in place they often help diffuse 

many of the problems that arise during a crisis. 

We digress here briefly to discuss our 

justification for combining the aviation and groundbased communities into one system. Perhaps the best 

reason for combining them is to ensure that there is a 

consistent message regarding the status of the 

volcano. One can imagine the possible confusion 

that could arise in populated areas if a volcano is at 

Red/Warning for aviation hazards but at 

Orange/Watch for ground hazards. All it would take 

would be one media or observatory report to confuse 

the two for a potential disaster to happen. Moreover, 

as restless volcanoes near populations escalate 

towards or de-escalate from an eruption, the 

information conveyed by alert levels and in daily 

updates is of equal importance to both communities. 

Many explosive eruptions may not affect both 

communities equally, but the differences may be 

slight. As long as regional airport operations are 

affected by ash fall, lava flows or lahars, airportsupported response and recovery efforts will be 

difficult or impossible to deploy. The only cases in 

which one community will be effected in the other 

not, are when volcanoes are very remote or when 

eruptive activity is non-explosive and far from 

airports. Overall we feel that there is more to be 

gained by combining these two groups within one 

system than by having two separate ones. The 

challenge for observatory scientists is to write 

eruption communications well enough so that each 

group can quickly identify and locate the volcanic 

phenomena of concern. 

Closing

There are many ways to develop a volcano alertlevel notification system and ours is but one of many 

(Scott, this volume). As stated in the title, this is a 

proposed system and we are in the process of testing 

it and evaluating it internally. Even now, we are 

trying to determine whether Red/Warning should 

only mean “hazardous eruption in progress” or stay 

with the current dual definition of “hazardous 

eruption in progress or hazardous eruption 
Session 2 – Page 41 

imminent.” Another area of discussion is 

whether we should set protocols as to how long 

we stay in Red/Warning—only for the duration 

of the eruption (which may be minutes to many 

hours) or for a set time period, perhaps 12 hours 

after the eruption has ended? The latter would 

cover the time period when ground-based 

catastrophic events would have occurred and 

most of the tephra would have moved 

substantially downwind of the volcano. As we 

move forward with this process, we would 

greatly appreciate comments as to potential 

problems and benefits of this proposed scheme 

from the aviation, ground-based, and 

volcanological communities. 

References Cited

ICAO (International Civil Aviation 

Organization), 2004, Handbook on the 

International Airways Volcano Watch, 

ICAO Document 9766-AN/968, 

http://www.icao.int/icaonet/dcs/9766_2_en.

pdf

Eichelberger, JC, Keith, TEC, Miller, TP, Nye, 

CJ, 1995, The 1992 eruptions of Crater Peak 

vent, Mount Spurr Volcano, Alaska: 

Chronology and Summary, in Keith, TEC, 

editor, The 1992 eruptions of Crater Peak vent, 

Mount Spurr Volcano, Alaska: U.S. Geological 

Survey Bulletin 2139, p. 1-18. 

Newhall CG, this volume, Promise and pitfalls in 

eruption forecasting. 

Newhall CG, Self S, 1982, The Volcanic Explosivity 

Index (VEI): an estimate of explosive magnitude 

for historical volcanism. J Geophys Res, v. 87, 

p. 1231-1238. 

Scott B, this volume, Volcanic alert systems: an 

overview of their form and function. 

Simkin T, Siebert L, 1994, Volcanoes of the World, 

2nd ed., Geoscience Press, Tucson, 349 p. 

Wunderman R, Siebert L, Luhr J, Simkin T, Venzke 

E, this volume, A global perspective on 

volcanoes and eruptions. 
P2.4 

Session 2 – Page 43 

MONITORING AND REPORTING OF KAMCHATKAN VOLCANIC ERUPTIONS 

Evgenii Gordeev1 (+7-415-22-59531; gord@emsd.iks.ru) 

Sergei Senjukov2 (+7-415-22-59523; ssl@emsd.iks.ru) 

Olga Girina1

 (+7-415-22-58627; girina@kcs.iks.ru) 

Institute of Volcanology and Seismology, Russian Academy of Sciences, PetropavlovskKamchatsky, Russia 

Kamchatkian Department, Geophysical Service, Russian Academy of Sciences, 

Petropavlovsk-Kamchatsky, Russia 

Kamchatka is a part of Pacific volcanic ring with 29 active volcanoes. Every year 2- 3 of these 

volcanoes produce explosive ash clouds that spread across heavily traveled international air 

routes between Asia and North America. The Kamchatka Volcanic Eruption Response Team 

(KVERT) has since 1993 provided reports and notices of volcanic activity. In collaboration with 

the Institute of Volcanology and Seismology (IVS) and Kamchatkan Experimental and 

Methodical Seismological Department (KEMSD) of the Russian Academy of Sciences, the 

KVERT staff monitors active volcanoes of Kamchatka seismically, by video and visual 

observations, and using satellite images for ash cloud tracking and detection of thermal 

anomalies. As of 2003, 28 remote seismic stations are operating at 11 of the most active 

volcanoes in Kamchatka and North Kurile Islands. Three volcanoes, Kyuchevskoy, Sheveluch 

and Bezymyanny are under control by video-camera system, which makes real-time images of 

volcanoes available on the Internet (http://emsd.iks.ru). Seismic observations are a universal tool 

used to reveal the beginning of volcano unrest and to recognize volcanic blasts of frequently 

weather obscured volcanoes. KVERT scientists have developed methods of estimating eruption 

plume height from the intensity of the seismic signals. In cooperation with the Alaska Volcano 

Observatory, KVERT examines data from Japanese and U.S. meteorological satellites. Several 

times a day, images from GMS (Geostationary Meteorological Satellite), GOES (Geostationary 

Operational Enviromental Satellites) and polar-orbiting satellites carrying AVHRR (Advanced 

Very High Resolution Radiometer) are examined for volcanic activity. Since 2002, KVERT has

used daily images from NOAA16 and NOAA17 satellites received by the Kamchatkan Center 

Communication and Monitoring (KCCM). In the future, KVERT will expand its monitoring and 

warning capacity by adding more seismic networks and video systems and by enhancing satellite 

analysis of Kamchatka and the adjacent Kurile Islands. 

 
P2.5 

Session 2 – Page 45 

VOLCANO-RELATED INFORMATION AVAILABLE ON THE 

INTERNET: FROM CURRENT ACTIVITY TO THE PAST 10,000 YEARS 

Gari Mayberry, US Geological Survey, Washington DC, USA 

Edward Venzke, Smithsonian Institution, Washington DC, USA 

James Luhr, Smithsonian Institution, Washington DC, USA 

Richard Wunderman, Smithsonian Institution, Washington DC, USA 

Lee Siebert, Smithsonian Institution, Washington DC, USA 

Marianne Guffanti, US Geological Survey, Reston, VA, USA 

Introduction

 A wealth of information is available on the 

Internet about volcanoes and the ash clouds they 

emit, but it can be a daunting task for pilots and 

aviation officials to find the most pertinent 

information. Scientists with the US Geological 

Survey’s (USGS) Volcano Hazards Program and 

the Smithsonian Institution’s Global Volcanism 

Program (GVP) recognize that information 

concerning volcanic activity should be readily 

available to the aviation community. To that end, 

they provide two pages of particular relevance on 

their websites: the GVP/USGS Weekly Volcanic 

Activity Report, and the USGS Current Updates 

for US and Russian Volcanoes. 

Worldwide Volcanic Information

 Up-to-date information about significant 

worldwide volcanic activity is available on a 

weekly basis via the online GVP/USGS Weekly 

Volcanic Activity Report at 

http://www.volcano.si.edu/reports/usgs/. The 

report is a joint project between the Volcano 

Hazards Program and GVP that became available 

to the public on November 1, 2000. 

 The most significant section of the website is 

the brief description of the activity that occurred at 

the volcano during the report week. These 

accounts include information about (1) volcanorelated activity that either did not result in an 

eruption or preceded and accompanied an eruption 

– i.e., increased seismicity, gas emissions, 

deformation, surficial changes, (2) eruptions, with 

emissions including lava flows, ash, and other 

fragmental volcanic material, (3) secondary 

activity such as mudflows/lahars and re-suspended 

ash, and (4) eruption impacts, including health 

impacts, airport closures, flights affected, and 

property damage. In each volcano report, 

volcanological terms that the general public may 

not be familiar with are linked to a photo glossary 

on the USGS Volcano Hazards Program website. 

In addition, acronyms and abbreviations are 

commonly used in the reports, so there is a link to 

a list with their meanings. 

 Background information from the GVP website 

is included with each volcano report that briefly 

summarizes the geological history of the volcano 

and noteworthy past eruptions. Each report also 

has links to maps showing the location of the 

report volcano in relation to nearby volcanoes and 

large cities, the source of the reported information 

when available on the Internet, and a link to more 

information, images, and data on the GVP website. 

 All volcano reports are archived on the Internet 

by volcano and report date, so that they are easily 

accessible. In the 4 years that the GVP/USGS 

Weekly Volcanic Activity Report has been 

available to the public (November 1, 2000 to 

November 2, 2004), there have been reports 

written about 146 volcanoes in 33 different 

countries and island nations (note that all reports 

document the minimum amount of activity in any 

given week due to under-reporting). A majority of 

reports (53) discuss small eruptions at volcanoes 

that had not erupted for at least 3 months (Table 

1). Small eruptions include ash emissions that did 

not rise higher than approximately 5 km above the 

volcano. Most of the remaining reports cover noneruptive volcanic activity (48) and ongoing 

activity (25) not considered anomalous. 
Session 2 – Page 46 

Table 1. Types of activity reported in the 

GVP/USGS Weekly Volcanic Activity Report 

during November 1, 2000 to November 2, 2004. 

Type of Activity Number of Volcanoes 

Non-eruptive, 

Precursory Activity 

48 

Ongoing Activity 25 

Small New Eruptions 53 

Large Eruptions 13 

Evacuations 20 

Deaths 2 

Injuries 2 

Aviation Impacted 12 

 Reports were written about 13 large eruptions – 

i.e., produced ash clouds that rose higher than 5 

km above the volcano and had significant impacts 

on populations or aviation (Table 2). Eight of 

these eruptions led to evacuations of residents near 

the volcanoes; eruptions at 12 other volcanoes led 

to evacuations when large eruptions did not occur 

(20 evacuations total since November 1, 2000.) 

Eruption-related deaths were reportedly caused by 

two eruptions. Injuries were reported from two 

eruptions, and numerous incidents occurred where 

people’s health was adversely affected by ash and 

gas 

Table 2: List of the 13 large eruptions reported in 

the GVP/USGS Weekly Volcanic Activity Report 

during November 1, 2000 to November 2, 2004. 

Volcano, Country Eruption Date 

Popocatépetl, México Dec. 2000 

Cleveland, USA Feb. 2001 

Merapi, Indonesia Feb. 2001 

Etna, Italy May-Aug. 2001 

Oct. 2002 

Mayon, Philippines June, July 2001

Nyiragongo, D. R. Congo Jan. 2002 

Pago, Papua New Guinea Aug. 2002 

Tungurahua, Ecuador Oct. 2002 

Reventador, Ecuador Nov. 2002 

Bezymianny, Russia July 2003 

Jan. 2004 

Anatahan, Mariana Islands May 2003 

Manam, Papua New Guinea Oct. 2004 

Grímsvötn, Iceland Nov. 2004 

 Ash from eruptions at 12 different volcanoes 

disrupted activities at airports and/or affected 

aircraft in flight (See Guffanti et al., this volume). 

The GVP/USGS Weekly Volcanic Activity Report 

provides valuable information about ash and 

aircraft/airport incidents by consistently 

documenting them in a timely manner 

 Timely reporting of volcanic activity does not 

always allow time for in-depth verification of 

information by scientists in the field or by 

GVP/USGS Weekly Volcanic Activity Report 

editors. Therefore, false reports can sometimes be 

included. Six false reports of eruptions have been 

included in the GVP/USGS Weekly Volcanic 

Activity Report, and were corrected once new 

information was received. 

 The GVP/USGS Weekly Volcanic Activity 

Report utilizes the wealth of volcano-related 

information available on the GVP website at 

http://www.volcano.si.edu/ by providing links to 

data about the report volcano on the website. 

While the GVP/USGS Weekly Volcanic Activity 

Report has provided brief updates on significant 

volcanism around the world for the past four 

years, the Smithsonian GVP has provided 

information since 1968 about Earth’s current 

eruptions and those that occurred in the past 

10,000 years. Monthly newsletters discussing 

current activity have been produced since 1975, 

and have been posted on the Internet since 1994. 

 For more than three decades, GVP has 

compiled descriptions, data, maps, and images of 

volcanoes and their eruptions in order to better 

understand the full range of Earth's eruptive 

activity and to make these resources available to 

the ever-broadening community interested in 

volcanism (Siebert and Simkin, 2002). Two 

previous hardcopy versions of the GVP volcano 

and eruption data (Simkin et al., 1981 and Simkin 

and Siebert, 1994) have been published, but in 

2002 the data became accessible on the GVP 

website (Venzke, et al., 2002). The development 

of the world wide web has made possible much 

wider and faster dissemination of these data, 

which are frequently updated. 

U.S. Volcanic Information

 For users specifically interested in current 

activity at volcanoes in the United States and 

Russia, the USGS Volcano Hazards Program 

website compiles daily-to-monthly volcano 
Session 2 – Page 47 

updates from all five volcano observatories in the 

United States and an observatory in Kamchatka. 

The USGS Current Updates for US and Russian 

Volcanoes page is available at 

http://volcanoes.usgs.gov/update.html. 

The page also has links to each individual 

observatory website where detailed information 

about the volcanoes within the observatory’s 

region of responsibility can be found. 

Summary

 The GVP/USGS Weekly Volcanic 

Activity Report, with links to the GVP website, 

and the USGS Current Updates for US and 

Russian Volcanoes page place air traffic 

controllers, pilots, and airport authorities abundant 

information regarding volcanic activity around the 

world literally at their fingertips to help them 

quickly make informed decisions when planning 

flight routes. 

References Cited

Guffanti, M., Casadevall, T.J., and Mayberry, 

G.C., this volume, Effects of volcanic activity 

on airports. 

Siebert, L., and Simkin, T., (2002-). Volcanoes of 

the World: an Illustrated Catalog of Holocene 

Volcanoes and their Eruptions. Smithsonian 

Institution, Global Volcanism Program, 

Digital Information Series,GVP-3, 

(http://www.volcano.si.edu/world/). 

Simkin, T., Siebert, L., McClelland, L., Bridge, 

D., Newhall, C., and Latter, J.H., (1981). 

Volcanoes of the World. Hutchinson-Ross, 

Stroudsburg, Pennsylvania, 232 p. 

Simkin, T., and Siebert, L., (1994). Volcanoes of 

the World, 2nd edition. Geoscience Press, 

Tucson, 349 p. 

Venzke, E., Wunderman, R.W., McClelland, L., 

Simkin, T., Luhr, J.F., Siebert, L., and 

Mayberry, G., (eds.) (2002-). Global 

Volcanism, 1968 to the Present. Smithsonian 

Institution, Global Volcanism Program Digital 

Information Series, GVP-4 

(http://www.volcano.si.edu/reports/). 
P2.6 

Session 2 – Page 49 

 VOLCANIC TREMOR AND ITS USE IN ESTIMATING ERUPTION PARAMETERS 

Stephen R. McNutt 

 Alaska Volcano Observatory, Geophysical Institute UAF, Fairbanks, AK 99775 USA 

Volcanic tremor, a continuous seismic signal, 

accompanies virtually all eruptions. Several 

published studies have examined relations between 

tremor reduced displacement (DR, a normalized 

amplitude measure; Aki and Koyanagi, 1981; Fehler, 

1983) and the Volcanic Explosivity Index (VEI; 

Newhall and Self, 1982) or ash plume height. The 

goals of these studies are to determine the physical 

relationships between tremor and eruptions and to use 

DR values to provide real-time estimates of eruption 

parameters. 

This study examines tremor for 50 eruptions from 31 

volcanoes. This is a significant expansion of the data 

set from an earlier study of 21 eruptions from 14 

volcanoes (McNutt, 1994). Several new trends are 

observed when DR is plotted versus VEI (Figure 1): 

1) large eruptions produce stronger tremor than small 

ones; 2) fissure eruptions produce stronger tremor 

than circular vents for the same fountain height (F in 

Figure 1); 3) eruptions with higher gas content (H in 

Figure 1) produce stronger tremor than those with 

low gas content (L in Figure 1); and 4) phreatic 

eruptions produce stronger tremor than magmatic 

eruptions for the same VEI (P in Figure 1). 

The three volcanoes with varying gas content are 

Redoubt 1989-1990, based on eruption type 

(vertically oriented pumice eruption versus dome 

collapse; Miller, 1994); Mount Spurr in 1992 based 

on SO2 measurements (Bluth et al., 1995); and 

Shishaldin volcano in 1999 based on presence or 

absence of large explosions on a pressure sensor 

(Caplan-Auerbach and McNutt, 2003). 

Using tremor DR to estimate eruption parameters is a 

statistical problem with several factors contributing 

to uncertainties. First, tremor occurs when volcanoes 

do not erupt as well as when they do. Based on a 

worldwide sample, 60-80 percent of tremor episodes 

accompany eruptions, while 20-40 percent of 

episodes do not. Thus, there is a significant chance 

that no eruption is occurring. Second, for each VEI, 

there is a range of DR, so it is possible to 

overestimate or underestimate the VEI. Hence there 

will always be a false alarm rate (~10 percent). 

Improvements can be made in the estimates if the 

types of eruptions, shapes of vents, and gas contents 

are known in advance. These can be estimated from 

previous eruptions or measured near-real-time from 

independent data. However, adding additional 

information takes time, delaying forecasts. A primary 

benefit of seismic data is that they are real-time, are 

not affected by darkness, and are usable during poor 

weather, although the signal-to-noise ratio can be 

worsened. Monitoring tremor DR is therefore an 

effective way to characterize eruptions in progress. 

References: 

Aki, K., and Koyanagi, R.Y. (1981). Deep volcanic 

tremor and magma ascent mechanism under Kilauea, 

Hawaii. Jour. Geophys. Res. 86, 7095-7110. 

Bluth, G.J.S., C.J. Scott, I.E. Sprod, C.C. Schnetzler, 

A.J. Krueger, and L.S. Walter (1995). Explosive 

emissions of sulfur dioxide from the 1992 Crater 

Peak eruptions, Mount Spurr Volcano, Alaska. In: 

T.E.C. Keith (Ed.) The 1992 Eruptions of Crater 

Peak Vent, Mount Spurr Volcano, Alaska. . U.S. 

Geol. Survey Bull. 2139, 37-45. 

Caplan-Auerbach J., McNutt S.R. (2003). New 

Insights into the 1999 Eruptions of Shishaldin 

Volcano Based on Acoustic Data. Bull. Volcanol. 65: 

405-17, 10.1007/s00445-002-0267-5 

Fehler, M. (1983). Observations of volcanic tremor at 

Mount St. Helens volcano. Jour. Geophys. Res. 88, 

3476-3484. 

McNutt, S.R. (1994). Volcanic tremor amplitude 

correlated with volcano explosivity and its potential 

use in determining ash hazards to aviation. U.S. Geol. 

Survey Bull. 2047, 377-385. 

Miller, T.P. (1994). Dome growth and destruction 

during the 1989-1990 eruption of Redoubt Volcano, 

Alaska. In: T.P. Miller and B.A. Chouet (Eds.), The 

1989-1990 Eruptions of Redoubt Volcano, Alaska. J. 

Volcanol. Geotherm. Res., 62, 197-212. 

Newhall, C.G., and S. Self (1982). The Volcanic 

Explosivity Index (VEI): An estimate of explosive 

magnitude for historical volcanism. J. Geophys. Res. 

87, 1231-1238. 

 
Session 2 – Page 50 

Figure 1. Reduced displacement, a normalized measure of amplitude, versus the Volcanic Explosivity Index for 50 

eruptions at 31 volcanoes. The regression line is from McNutt (1994) based on a smaller data set and is shown for 

comparison. Fissure eruptions are labeled F; a phreatic eruption is labeled P; deep (40 km) tremor from Kilauea is 

labeled D (no eruption for this one); and three pairs of values from VEI=3 eruptions with high and low gas content 

are labeled H and L, respectively. 
P2.7 

Session 2 – Page 51 

SURPRISE/SUDDEN ONSET ERUPTIONS: THE CASE OF REVENTADOR VOLCANOECUADOR, 03-NOVEMBER, 2002 

Patricia Mothes, Minard L. Hall, Patricia Ramón and Hugo Yepes 

Instituto Geofísico, Escuela Politécnica Nacional, Quito-Ecuador 

Not all volcanoes show a progressive build up over weeks and months of precursory activity 

prior to a major eruption. Several of these include Redoubt (1989) and most recently Reventador 

in eastern Ecuador. Prior to Reventador’s VEI 4 subplinian eruption on 03 November, 2002, 10 

seismic events were registered on 06 October, 2002 by the two telemetered seismic stations 

closest to the active cone. Superficial manifestations observed from a nearby construction camp 

were minor. On the day of the eruption only seven hours of tremor and >100 local earthquakes 

preceded the paroxysmal eruption at 09H12 (LT) that resulted in a 17 km high ash-rich column 

and 5 andesitic pyroclastic flows which descended 9 km down valley. Ash clouds entered the 

populated InterAndean Valley and ash began falling between 12H00 and 16H00 depositing a 5- 

15 mm thick layer. Quito’s International Airport, 100 km west of the volcano, was closed 

officially at 12H45, hence most aircraft remained at the airport and were completely covered by 

the ash. Reventador has had at least 7 eruptive periods since 1900. In this most recent episode, 

the rapid ascent of volatile-rich magma was mainly aseismic. Only telemetered seismic stations 

operating directly on the cone may have provided a clearer warning of the impending eruption. 

Reventador is similar to several other active volcanoes in Ecuador which have minimal or no 

monitoring because of the “low” direct risk they present to important population centers. 

Airlines and local Civil Aviation could opt to contribute to establish more intense monitoring of 

these volcanoes to maximize eruption predictive capacity and at the same time have plans in 

place to deal with unexpected-surprise eruptions. 

 
P2.8 

Session 2 – Page 53 

ASHFALL SCENARIOS AND AVIATION IMPACTS OF FUTURE ERUPTIONS OF 

COTOPAXI VOLCANO-ECUADOR 

Patricia Mothes, Minard L. Hall, Pablo Samaniego and Hugo Yepes 

Instituto Geofísico, Escuela Politécnica Nacional, Quito-Ecuador 

Cotopaxi is a 5900 meter high stratocone on the eastern edge of the densely populated 

InterAndean Valley. In November, 2001 Cotopaxi’s monitoring network began to display 

frequent and intense anomalous seismic events. Although this activity has mostly subsided, it 

may be a long-term warning that a slow awakening is occurring. The volcano’s last important 

eruption was in June, 1877. Covered by ~14 km2 of ice and snow, Cotopaxi is well known for its 

destructive lahars that have traveled down all 3 main drainages. Ashfalls also had important 

consequences for the agriculturally-based communities during the 13 notable VEI 3-4 magnitude 

eruptions of the 18th and 19th centuries. Extensive field mapping of 10 main ash fall units of the 

Holocene shows that the bulk of the coarser tephra has been deposited to the W-NW of the cone 

and that in only two cases have important ash/pumice layers been deposited to the east. As seen 

during recent eruptions of other Ecuadorian volcanoes, windshearing is common after the 

column enters the stratosphere, directing the fines-component of ash clouds eastward. Historic 

accounts following Cotopaxi eruptions report fine ash falls as far north as Pasto- Colombia, to 

Piura- Perú, to the south, and westward upon coastal Ecuador where ash falls often persisted 4 to 

5 days. Future eruptions are likely to be of similar VEI 3-4.5 magnitude, producing plinian 

columns and pyroclastic flows, which have the effect of injecting ash-rich clouds high into the 

stratosphere, potentially affecting national and international airline traffic for many days in all of 

Ecuador, and perhaps on a regional scale. In all probability, the three main international airportsQuito, Latacunga and Guayaquil will suffer some consequences of ashfalls. 

 
P2.9 

Session 2 – Page 55 

AIRBORNE ASH HAZARD MITIGATION IN THE NORTH PACIFIC: A MULTI-AGENCY, 

INTERNATIONAL COLLABORATION 

Christina Neal and Alaska Volcano Observatory staff, U.S. Geological Survey, Anchorage, AK, 

USA 

Olga Girina, Kamchatkan Volcanic Eruption Response Team, Petropavlovsk, Russia 

Gail Ferguson, Federal Aviation Administration, Anchorage, AK, USA 

Jeffrey Osiensky, NOAA, National Weather Service, Anchorage, AK, USA 

More than 100 active volcanoes bordering the Pacific Ocean from southern Alaska, along the 

Aleutians, Kamchatka and through the Kuriles, pose a significant risk to aviation. To address 

this problem, scientific institutes, federal and state/regional governmental agencies, international 

organizations, and private industry work together to ensure effective volcanic hazard warnings. 

The principal earth science agencies responsible for detecting and issuing warnings of volcanic 

unrest in Alaska and Russia are the Alaska Volcano Observatory (AVO) and the Kamchatka 

Volcanic Eruption Response Team (KVERT). AVO and KVERT utilize real-time seismic 

networks, satellite remote sensing of ash and thermal anomalies, and visual observations to 

detect and characterize volcanic activity. Warnings are issued as quickly as possible by phone, 

fax, and the Internet to an established recipient list. Information is also rapidly posted on the 

Internet. AVO works closely with the National Weather Service, the Federal Aviation 

Administration, and others to ensure that formal operational guidance to the aviation community 

contains all critical volcanic hazard information. KVERT has a similar relationship with the 

regional aviation and meteorological authorities in Kamchatka. AVO and KVERT also issue 

weekly status reports on all seismically monitored volcanoes and conduct scientific studies in 

support of hazard assessments. Both groups utilize a 4-level, color-coded alert scheme to 

summarize the severity of volcanic unrest and hazard. Agency responsibilities, relationships, 

and operational protocols for eruptions in Alaska are formalized in the “Alaska Interagency 

Operating Plan for Volcanic Ash Episodes”. Frequent review of response protocols is necessary 

to maintain proficiency and to meet demands for increasingly rapid communication of volcanic 

hazards. 
P2.10 

Session 2 – Page 57 

GROUND-BASED DETECTION OF VOLCANIC ASH AND SULPHUR DIOXIDE 

Fred Prata, CSIRO Atmospheric Research, Aspendale, Australia 

Cirilo Bernardo, CSIRO Atmospheric Research, Aspendale, Australia 

We present the first thermal infrared image data showing detection and discrimination of 

volcanic ash and sulphur dioxide gas emitted from erupting volcanoes. The images are acquired 

from a new multichannel uncooled thermal imaging camera suitable for deployment within ~10 

km of an active volcano. Algorithms for ash and SO2 detection are described. Images from the 

system, named G-bIRD (Ground-based InfraRed Detector) are acquired rapidly (within a few 

seconds), analysed and transmitted via satellite or landline to a computer with access to the 

Internet and utilising a standard web browser. Tests of the system have been undertaken at Etna 

and Stromboli, Italy, at Anatahan, NMI and at Tavurvur, Rabaul and results will be presented. 

G-bIRD offers a new means for monitoring hazardous volcanic substances from the ground and 

could provide complementary information for providing volcanic ash and SO2 warnings to the 

aviation industry. 
P2.11 

Session 2 – Page 59 

THE NEW ZEALAND VOLCANO ALERT LEVEL SYSTEM – 

ITS PERFORMANCE IN RECENT ERUPTIVE ACTIVITY 

Bradley Scott, Institute of Geological and Nuclear Sciences, 

Wairakei, New Zealand 

In November 1994, the New Zealand Ministry of Civil Defence introduced a new annex 

entitled ‘Volcanic Impacts’ into the National Civil Defence Plan. This was based on a five 

level volcanic alert system that encompassed all volcanoes in New Zealand. The newly 

introduced volcano alert system received its first significant test with eruptions at Ruapehu 

volcano from December 1994-April 1995; we learnt some important lessons that highlighted 

several operational problems with the system. A revised system was introduced in August 

1995 by the Ministry. On 18 September 1995, a major episode of eruptive activity 

commenced from Crater Lake, Mt Ruapehu with large explosions expelling the crater lake, 

producing lahars through ski fields and an eruption plume over 10 km high; activity 

continued for weeks, testing the revised system. The revised volcano alert system is based on 

six levels and has two separate schemes that clearly differentiate between frequently active 

volcanoes and reawakening activity at a dormant volcanic centre. The system provides an 

indication of eruptive status and is not intended to be predictive. This revised system has been 

effectively used during the 1995 and 1996 eruption episodes at Ruapehu and during recent 

eruptions at White Island (1998-2001). The introduction of a volcano alert level system has 

produced a uniform platform for responding agencies like central and local government, 

critical industries/services, aviation and the public to focus their response on. Based on 

experiences with the Ruapehu eruptions, volcano contingency planning now uses the alert 

levels as the basic building block for that process. This presentation will outline aspects of the 

recent eruptions, the interaction with the alert levels and comment on our experiences. 
P2.12 

Session 2 – Page 61 

STATUS OF MONITORING ACTIVE VOLCANOES OF THE KURILE ISLANDS: 

PRESENT AND FUTURE 

Alexander V. Rybin1

, Y.V. Karagusov2, Pavel Izbekov3, Nikolay S. Terentyev2, Vyacheslav B. 

Guryanov1

, Christina Neal4, and Ken Dean3

1

 Institute of Marine Geology and Geophysics, Yuzhno-Sakhalinsk, Russia 

2

 DalInformGeoCenter, Yuzhno-Sakhalinsk, Russia 

3

 Alaska Volcano Observatory, Fairbanks, Alaska, USA 

4

 Alaska Volcano Observatory, USGS, Anchorage, Alaska, USA 

Abstract 

 Important international air routes from 

Asia to North America are located immediately 

above and to east of the Kurile Islands. There are 

thirty six volcanoes within the Kurile Island chain 

which are considered to be active, explosive, and 

capable of sending volcanic ash to altitudes used 

by commercial airliners. The remoteness and the 

lack of communication links hinder the 

development of the ground-based monitoring of 

the active volcanoes of the Kuriles. Therefore, the 

efficient use of satellite imagery and coordinated 

multi agency efforts in response to volcanic events 

are required to reduce the risk for aviation. 

 Part of the “Pacific Rim of Fire”, the 

1250-km-long chain of Kurile Islands extends 

from Kamchatka Peninsula, Russia to Hokkaido 

Island, Japan. It consists of 68 volcanic centers, 

among which 36 are considered to be active, i.e. 

have records of historic eruptive activities (Figure 

1). On average, large eruptions (VEI 4) have 

occurred in the Kuriles every 33 years; moderatelarge (VEI 3) eruptions every 22 years; moderate 

eruptions (VEI 2) every 11 years; and small 

eruptions (VEI 1) every 1-5 years. Sixty eruptions 

were recorded in the Kuriles during the 20th

century, among which the most significant were 

the eruptions of Tiatia, Grozny, Sarychev, 

Severgin, Raikoke, Ebeko, and Alaid (Gorshkov, 

1967; Simkin & Siebert, 1994). The most recent 

examples include the eruption of Chikurachki 

volcano in April-June 2003 and the eruption of 

Chirinkotan volcano in July 2004. Eruptions are 

typically explosive and capable of sending 

volcanic ash to an altitude of 11 km (36,000 ft) 

and higher, thus posing a potential danger to 

aviation. 

 Although the population of the Kuriles is 

quite sparse, there are several permanent 

settlements on the southern islands of Kunashir, 

Iturup and Shikotan, as well as on the northern 

islands of Paramushir and Shumshu. With the 

exception of the settlement on the Shikotan Island, 

all others are located in the vicinity of active 

volcanoes, and eruptions may also cause a 

significant impact on a population and 

infrastructure of the settlements. 

 The most reliable method of volcano 

monitoring includes the use of ground-based 

seismic networks providing real-time data on the 

seismicity beneath active volcanoes. An increase 

in seismicity may be used as an early warning of 

an eruption. Unfortunately, there are no permanent 

seismic networks in the Kuriles. At present, there 

are only four single component seismic stations in 

the entire Kurile arc (on the flank of the Alaid 

volcano, in Kurilsk, Yuzhno-Kurilsk, and SeveroKurilsk settlements). These stations provide 

rudimentary seismic data for a few volcanoes, 

whereas the majority of the active volcanoes are 

tens to hundreds of kilometers from the nearest 

station. Installation of the permanent local seismic 

networks is expensive and feasible only for a few 

volcanoes which pose a threat to local 

communities (i.e. Tiatia, Mendeleev, Grozny, 

Baransky, Chirip, Ebeko, Chikurachki, and Alaid). 

Remoteness and the lack of communication links 

will likely preclude the establishment of the 

regular seismic monitoring (and/or ground 

observations) for most of the Kuriles for the next 

few decades. 

It appears that remote sensing is the most 

convenient and cost-effective approach to regular 

volcano monitoring of the Kuriles. At present, two 

major sources of the satellite data are used by our 
Session 2 – Page 62 

group in daily observations: (1) AVHRR data 

from the NOAA series of polar orbiters and (2) 

MODIS data from Terra and Aqua satellites. 

 From 1995 to 2000, AVHRR data from 

NOAA-12 and NOAA-14 satellites have been 

acquired locally by the Institute of Marine 

Geology and Geophysics (IMGG) using the 

“ScanEx” receiving station made by the Research 

& Development Center ScanEx, Moscow 

(http://www.scanex.ru). Although there were a few 

confirmed small eruptive events during this period 

of observation the low spatial resolution of 

AVHRR imagery did not allow their detection. For 

instance, according to visual observations by on 

site observers a phreatic eruption of Kudriavy 

volcano on October 7, 1999 produced a small 

volcanic ash cloud, which reached an elevation of 

1000 meters above sea level. The temperature of a 

small, hydrothermally heated area at the volcano 

reached 30°C with the temperatures of emissions 

from individual fumaroles exceeding 900°C. This 

activity was not detectable in either the visual, or 

infrared bands of AVHRR imagery. Meanwhile, 

the larger scale ash producing eruptive events in 

the neighboring Kamchatka have been reliably 

detected and reported to our Kamchatkan 

colleagues, e.g. 1995 eruption of Bezymianny 

(Abdurakhmanov et al. (2001). 

Since 2001 MODIS data have been 

acquired by the DalInformGeoCenter of the 

Ministry of Natural Resources of Russia in 

Yuzhno-Sakhalinsk using the “UniScan” ground 

receiving station made by the aforementioned 

R&DC ScanEx. Compared to AVHRR, MODIS 

data has significantly improved spectral and 

spatial resolutions, i.e. 36 channels in visual, NIR 

and IR spectrums with 250, 500 and 1000 meter 

resolutions, respectively. Since the launch of Aqua 

satellite in 2002, we have been able to acquire two 

swaths daily for the Kuriles. The entire station 

mask covers the area from the Arctic regions to 

Taiwan Island and from the Anadyr Bay to the 

Western Siberia (Figure 2). In 2003, the 

DalInformGeoCenter resumed the acquisition of 

NOAA AVHRR data. At present, more than 

twenty two swaths are received daily for the 

Kuriles from NOAA-12, 14, 15, 16, and 17 

satellites. Our monitoring capabilities will improve 

following the anticipated upgrade of the receiving 

station by summer 2004, which will allow 

acquisition of MSU-E and MSU-SK data from the 

Meteor-3M satellite with 35-m and 250-m ground 

resolutions respectively. 

Beginning in January 2003, our Sakhalinbased group of scientists from IMGG and 

DalInformGeoCenter has performed satellite 

observations of the Kurile Islands on a regular 

basis. The high spatial resolution of MODIS 

imagery complemented by the high temporal 

resolution of AVHRR data allowed us to observe 

the 2003 Chikurachki eruption (Figure 3) as well 

as the manifestations of moderate volcanic 

activity, i.e. steam plumes at Sinarka and Severgin 

volcanoes, mud flows from Tiatia volcano (Figure 

4), and most recently the gas and ash plume at 

Chirinkotan volcano. Because of a high volume of 

the original data, it is first processed at the 

receiving stations of DalInformGeoCenter, which 

includes (1) acquisition of the raw data from 

satellites, pre-processing and calibrating, (2) 

georeferencing the data, (3) extracting the sub 

sectors covering the Kuriles (Figure 2), and (4) 

converting data to BMP and JPEG formats. This 

allows us to reduce the MODIS data to three files 

totaling 5 Mb in size (Table 1). As soon as 

processing is completed, these images are sent via 

email to the Volcanological Laboratory of the 

IMGG, where they can be interpreted by 

volcanologists. 

Over the course of the next year, we hope 

to streamline this process to improve the 

timeliness of observation and reporting. We also 

intend to incorporate any information from Kurile 

seismic stations and ground observers and 

eventually distribute Kurile Volcano Information 

Statements to aviation and meteorological 

authorities for wider distribution in support of 

aviation safety. At present, we are still gathering 

financial and organizational support and working 

with colleagues at the Alaska Volcano 

Observatory and KVERT to develop reliable 

communication protocols. 
Session 2 – Page 63 

References 

Abdurakhmanov A.I., Bulgakov R.F. & Guryanov 

V.B (2001) An analysis of a thermal 

anomaly due to eruption products of 

Bezymianny volcano discharged October 

6-8 1996 based on NOAA satellite 

spectrozonal information. Volcanology 

and Seismology, v.5, pp. 63-72 (in 

Russian). 

Gorshkov, G.S. (1967) Volcanism of the Kurile 

island arc, Academy Nauk USSR, 

Moscow, 286 pages (in Russian). 

Dean, K. G., Dehn, Jon, Engle, Kevin, Izbekov, 

Pavel, Papp, Ken, and Patrick, Mathew 

 (2002) Operational satellite monitoring of 

volcanoes at the Alaska Volcano 

Observatory. in Harris, A. J. H., Wooster, 

M. J., and Rothery, D. A., eds., 

Monitoring Volcanic Hotspots Using 

Thermal Remote Sensing: Advances in 

Environmental Monitoring and Modelling, 

v. 1, n. 3, p. 70-97, available at 

http://www.kcl.ac.uk/advances 

Simkin, T.S. & Siebert, Lee (1994) Volcanoes of 

the world: a regional directory, gazetteer, 

and chronology of volcanism during the 

last 10,000 years. 2 ed. 1994: Geoscience 

Press, Tucson, AZ, 349 pages.

Table 1. MODIS bands used to produce the color-composite images used in our daily monitoring 

MODIS file name (example) 

Spatial 

resolution 

(meters) 

Bands Wavelength range Image 

size 

(Mb) 

Application 

MOD02QKM.A0403040013r 250 1 

2 

620-670 nm R,B 

811-876 nm G 3 Volcanic clouds 

MOD02HKM.A0403040013r 500 

3 

5 

7 

469-479 nm B 

1230-1250 nm G 

2105-2155 nm R 1,5 Volcanic clouds and 

thermal anomalies 

MOD021KM.A0403040013r 1000 

20 

22 

23 

3,66-3,84 um B 

3,929-3,989 um G 

4,020-4,080 um R 

0,6 Thermal anomalies 
Session 2 – Page 64 

Figure 1 Map of Kurile Islands. The locations of active volcanoes are indicated by solid dots, main 

settlements are indicated by solid boxes with their names underlined. 
Session 2 – Page 65 

Figure 2 The DalInformGeoCenter's station mask for NOAA series polar orbiters (red circle) and for 

Terra, Aqua, and Meteor-3m satellites (black dotted circle). The Kuriles sub sector is shown by a 

black open rectangle. 
Session 2 – Page 66 

Figure 3 Color-composit MODIS image of the erupting Chikurachki volcano acquired on April 22, 

2003. 

Figure 4 Color-composit MODIS image acquired on April 11, 2003 showing the mud flow from the 

Otvazhny crater of Tyatya volcano. 
TOTAL WATER CONTENTS IN VOLCANIC ERUPTION CLOUDS AND IMPLICATIONS FOR 

ELECTRIFICATION AND LIGHTNING*

Earle R. Williams1

, Stephen R. McNutt2

1

MIT Lincoln Laboratory, Lexington, Massachusetts 2

UAF Geophysical Institute, Fairbanks, Alaska 

1. INTRODUCTION

 The fundamental role of ice particle collisions in the 

separation of electric charge and generation of lightning 

in thunderclouds is now reasonably well established 

(Latham, 1981; Williams, 1985; Saunders, 1995). 

Charge separation and lightning are also prevalent in 

volcanic eruptions. A recent literature survey by 

McNutt and Davis (2000), and its recent extension, has 

shown more than 150 incidents of volcanic lightning. 

The efficacy of the ice-based process in thunderclouds 

has raised the interest in the possible applicability of the 

same process to a class of explosive volcanic eruptions. 

This study is concerned with an evaluation of volcanic 

eruptions as atmospheric ice factories. 

 The behavior of water in magma within the Earth is 

reasonably well understood in volcanology, and the 

behavior of water in the atmosphere is adequately 

understood in meteorology. The perceived gap in 

understanding lies in the transition from Earth to 

atmosphere. This study is aimed at bridging this gap. 

 

2. WATER CONTENT IN EXPLOSIVE MAGMA

 Volatiles in magma have been well studied (Johnson 

et al, 1993; Wallace and Anderson, 2000; Wallace, 

2004). The volatiles of greatest scientific interest have 

been H2O, CO2, and SO2, but water is dominant in total 

mass by more than an order of magnitude. The solubility of water in magma is known to increase with pressure, and this physics is basic to explosive volcanism 

________________________________________ 

* This work was sponsored by the National Aeronautics and 

Space Administration (NASA) Contract No. F19628-00-C0002. Opinions, interpretations, conclusions, and recommendations are those of the authors and are not necessarily 

endorsed by the U.S. Government. 

Corresponding author address: Dr. Earle R. Williams, 

Massachusetts Institute of Technology Lincoln Laboratory, 244 Wood St., Lexington, MA 02421-0000, 

earlew@ll.mit.edu 

Corresponding author address: Dr. Stephen R. McNutt, 

Alaska Volcano Observatory, UAFGI, P.O. Box 757320, 

Fairbanks, AK 99775-7320, 

steve@giseis.alaska.edu

(Wilson et al, 1980). The water contents of magmas are 

traditionally estimated as a percent by weight of the 

magma. Numbers in the literature in a wide variety of 

studies, sampled in Table 1, are remarkably consistent.

Volcano Water Content

(Wt %) Investigator

Bezymianni 

(1955) 4 Markinen (1962) 

Cerro Negro 3 – 6 Roggensack et al 

(1997) 

Fuego 1 – 6 Sisson and Layne 

(1993) 

Mt. St. Helens 4.6 – 6.1 Carey et al (1995) 

Gardner et al (1995) 

Pinatubo (1991) 5 Wallace and 

Gerlach (2004) 

Vesuvius (79 AD) 3.5 – 4.7 Cornell (1987) 

Table 1: Water Content of Explosive Magma

 The water contents in Table 1 are large from a 

meteorological perspective. For example, a cubic meter 

of magma at depth with mean magma density 2.5 

gm/m3

 and with 4% water by weight contains 100 

kilograms of water. In condensed form, this is 100 

liters of liquid. Following the Clausius-Clapeyron 

relation, this amount in vapor form is sufficient to 

saturate 4000 m3

 of tropical atmosphere at a temperature T=30o

C. At a temperature T= -50oC typical of 

conditions at the tops of Plinian eruption clouds, the 

same mass of water vapor is sufficient to ice-saturate 

more than 107

 m3 of atmosphere. 

3. EXPLOSIVE ERUPTIONS AND THE 

RELAXATION VOLUME 

 Water is widely recognized as the working substance 

of explosive volcanic eruptions. Water dissolved in 

magma at depth, and with typical weight % values 

given in Table 1, is exsolved to vapor in bubbles as the 

magma ascends and the pressure declines (Wilson et al, 

1980). If the vapor phase remains disconnected in the 

magma, typical of isolated bubble inclusions in the 

magma matrix and typical of explosive eruptions over 

subduction zones, large confined gas pressures can 

develop. When the highly viscous magma fractures at a 
critical porosity (Gardner et al, 1996), the stored energy

is released explosively, with an ultimate relaxation of

the elevated pressure to ambient atmospheric pressure

Po. 

Conservation of energy for a simple spherical

explosion equates the available energy E and the

pressure-volume work performed against the ambient 

atmospheric pressure Po: 

 E = Po (4πR3

/3) (1) 

A rough estimate for the explosion radius R, the socalled ‘relaxation radius’ (Few, 1980), is then given by:

 R = (3E/4πPo)

1/3 (2) 

 This process is illustrated in Figure 1. Though 

ignored in this simple calculation, the relaxation volume will invariably be highly turbulent and involve a 

homogenization of the exploding material with the 

ambient atmosphere. Figure 1 also provides numerical 

estimates for different kinds of explosions. Detonations

of small Chinese firecrackers have relaxation radii of

centimeters, whereas energetic Fourth of July ‘bombs’ 

show relaxation smoke clouds of order meters. For a 

Krakatoa-level explosive eruption with estimated total

energy 1017 joules, the relaxation radius is more than 

4000 m. These scales are commensurate with the 

updraft widths of thunderstorm supercells (Williams,

2001), the largest and most violent form of convection

known to terrestrial meteorology. 

 

Figure 1: The eruption bomb based on water substance:

illustration of the physical process of the relaxation radius, 

and some calculated values. 

 The relaxation radius concept was developed

initially to treat the cylindrical explosions around 

lightning channels (Few, 1980), with the aim of estimating the dominant acoustic frequency of thunder.

The dominant acoustic wavelength is of the order of the 

relaxation radius. For this reason, Chinese firecrackers

emit in the acoustic range for human hearing and

exhibit a sharp ‘crack’, whereas much longer wavelengths are dominant for explosions in the category of 

volcanic eruptions, inaudible at distance. Hence there

is current interest in detecting volcanic eruptions 

worldwide with infrasonic methods (Bass et al, 2004). 

4. THE WATER CONTENT AND 

TEMPERATURE IN ERUPTION CLOUDS 

 

The relaxation volume together with estimates of

magma water content and temperature enable estimates

of both the average water content and temperature of 

eruption clouds. In both cases, it is assumed that the 

magma property is distributed homogeneously within

the ultimate relaxation volume. 

The water content is considered first. A lower

bound on cloud water content is considered by assuming the ambient atmosphere to be completely dry. The

favorable assumption is also made that all of the water 

dissolved at depth is released to the atmosphere in the

explosion. This assumption is supported by the observations that the porous (water vapor) phase is connected

(Gardner et al, 1996) in post-explosive tephra. Under 

this assumption, the mean cloud water content (MWC) 

is simply: 

 MWC = total water in magma

 relaxation volume (3) 

Energy E of explosion invested in expansion

against ambient pressure PO

Relaxation

Radius

 

 

R = 3

4π

E

PO

⎛ 

⎝ ⎜ 

⎞ 

⎠ ⎟ 

1

3

Chinese 

Firecracker

Source E (joules) R (m)

30 joules 2 × 10-2 m

Stick of

Dynamite

2 × 106 joules 0.6 m

1 kT

Explosive

4.2 × 1012 joules 220 m

Krakatoa

Eruption

1017 joules 4300 m

PO

4

3 πR3 ⎛ 

⎝ ⎜ ⎞ 

⎠ ⎟ = E

Energy E of explosion invested in expansion

against ambient pressure PO

Relaxation

Radius

 

 

R = 3

4π

E

PO

⎛ 

⎝ ⎜ 

⎞ 

⎠ ⎟ 

1

3

Chinese 

Firecracker

Source E (joules) R (m)

30 joules 2 × 10-2 m

Stick of

Dynamite

2 × 106 joules 0.6 m

1 kT

Explosive

4.2 × 1012 joules 220 m

Krakatoa

Eruption

1017 joules 4300 m

Chinese 

Firecracker

Source E (joules) R (m)

30 joules 2 × 10-2 m

Stick of

Dynamite

2 × 106 joules 0.6 m

1 kT

Explosive

4.2 × 1012 joules 220 m

Krakatoa

Eruption

1017 joules 4300 m

PO

4

3 πR3 ⎛ 

⎝ ⎜ ⎞ 

⎠ ⎟ = E

 

 = (wt%)(total tephra mass)

 (E/Po) (4) 

 = (wt%)M Po

 E (5) 

A useful reference point for total energy E is the 

design threshold for the Comprehensive Test Ban 

Treaty (CTBT) network (Sullivan, 1998): a bomb yield

of 1 kiloton (1 kT = 4.2 x 1012 joules). The total energy

on the scale of Volcanic Explosivity Index (VEI) 

(Simkin and Siebert, 1994) is not specified, but if the 

gravitational potential energy of the lofted tephra is 1%

of the total energy, then a 1 kT event is at the low end 

of the VEI scale (VEI~0) where the tephra volume M 

~104

 m3. Following Figure 1, the relaxation radius for a 

1 kT total energy is ~220 meters. 

If M is proportional to energy, the general assumption in considerations of VEI (Simkin and Siebert,

1994), and wt% is independent of eruption magnitude 

 
(broadly supported by the results in Table 1), then it 

follows that: 

 MWC = (wt%) (620) gm/m3 (6)

And for a representative value of wt% = 5 (based on

Table 1):

 MWC ~ 30 gm/m3 (7)

From a meteorological perspective, this number is

again large. It exceeds by 50% the value needed to 

saturate air at 30oC. It exceeds by more than two orders

of magnitude the value needed to saturate the upper 

troposphere at typical ambient temperatures. These

comparisons suggest that the assumption of a dry

entrained atmosphere is not a bad one, because the

entrainment of a realistic moist atmosphere would not

change the estimates appreciably. The magma water 

dominates the water budget. 

 Here it has been assumed that the eruption cloud will

have the same temperature as the atmospheric environment in which it is mixed. Such is not strictly the case, 

but the cloud temperature can be estimated from similar 

considerations of the relaxation volume. 

 If the pre-explosive hot porous magma causing a

volcanic explosion has temperature TM and volume VM, 

then the average temperature of the eruption cloud can 

be estimated from the volume mixing law:

 VMTM + VATA = (VM + VA) TC (8) 

 

 TC = VMTM + VATA (9) 

 (VM + VA) 

 VM is directly related to the VEI (Simkin and 

Siebert, 1994) and VA is essentially the relaxation 

volume. Taking values for the nominal 1 kiloton 

explosion, VEI = 0 case, we have VM = 104

 m3, VA = 

4.2 x 107

 m3, TM = 1000oC, TA = 30oC, we obtain a

mean cloud temperature from equation (1):

 TC ~ 30.2oC (10)

which is only 0.2 o

C warmer than the atmospheric

environment. This modest temperature perturbation is

expected in general because VM <<VA, despite the large 

temperature contrast between magma and atmosphere. 

This result suggests that the rapidly rising cumuliform towers in explosive eruptions are caused primarily 

by the kinetic energy of the explosions (on the way to

the relaxation radius), rather than by cloud buoyancy

forces set up by cloud-atmosphere temperature contrasts. This conclusion must be considered tentative 

however, as it is based on a thorough mixing of the

explosion emission over the entire relaxation volume. 

In the case of the 1980 Mt St Helens eruption, the 

lateral blast that initiated the eruption was clearly NOT 

well mixed with environmental air (Kieffer, 1981), and 

substantial enhancements of temperature (>100 oC)

were documented. Modelling studies of eruptions (e.g.,

Woods and Self, 1992) show 20-30 o

 C temperature

contrasts between plume and environment. Furthermore, Pack et al (2000) have documented thermal 

anomalies from space indicative of strong temperature 

perturbations in Plinean eruptions, but more interpretation of these anomalies is needed. For the calculations

here, we are not concerned with the short time scales of

the initial blast, however, but rather the disposition of

temperature and water substance at the time of ‘relaxation’. 

5. SUPPORTING OBSERVATIONS OF WATER

SUBSTANCE IN VOLCANIC ERUPTION

CLOUDS

 The foregoing calculations suggest that condensation 

of water vapor to the liquid and solid phase should be a

common occurrence in explosive volcanic eruptions. 

How do these simple predictions square with available 

observations?

 Regarding the evidence for liquid water in volcanic

eruptions, Clarke (1821) describes observations of the

May 31, 1806 eruption of Vesuvius in Italy: “two

places were deluged with a thick black rain, consisting 

of a species of mud filled with sulphureous particles”. 

In the case of the more recent Mt St Helens eruption in 

1980, Waitt (1981) reports, “...dark gray pisolitic mud

fell from the second high-level cloud”, and Thompson

(2000) notes “...mud balls the size of a half-dollar fell

like rain for several minutes”. In tropical eruptions, wet

conditions have also been documented, though in these 

cases the interpretation is less clear-cut, owing to the 

abundance of moisture and the prevalence of natural

precipitating convection that may be processing atmospheric water vapor rather than magma water. Nevertheless, the reports form the tropics are worth noting in

light of the predictions. In the case of the Rabaul

volcano, Rose et al (1995) reported, “some of the ash 

fallout was very wet, and a ‘rain of mud’ occurred in

some areas around Rabaul”. For the Pinatubo (Philippines) eruptions in 1991, Oswalt et al (1996) reported:

“Tephra fall continued throughout the day...varying 

from completely dry ash through a cement-like mud, to

muddy water”. Paladio-Melosantos et al (1996) document Pinatubo conditions as follows: “An area of about

2000 square kilometers was blanketed by 10 to 25

centimeters of rain-soaked tephra.” Note that a typhoon

 
accompanied the Pinatubo eruption so some of the 

water came from the typhoon. 

In addition to this evidence for liquid water, ice has 

been reported in volcanic eruptions in a few instances. 

Owing to the lower saturation thresholds and the 

prevalence of subfreezing conditions in the upper 

troposphere, ice is expected to be the most prevalent 

fate of magmatic water. In the case of the Surtsey 

volcano in Iceland, Thorarinsson (1966) reported, 

“...fallout of icy pyroclasts onto local ships was described as hail showers with a grain of ash within each

hailstone”. Using remote sensing methods on the

Rabaul volcano, Rose et al (1995) “...report the detection, using a satellite-borne infrared sensor, of >million

tons of ice in the cloud”. For the 1980 eruption of

Mount St. Helens, Hoblitt (2000) states, “upon the 

arrival of the yellow cloud, ice and ice-cold mudballs 

began to fall...”. Of the same eruption, Thompson

(2000) notes: “ice-cube sized chunks of glacier ice 

began pelting the ground...”. In the latter case, the 

interpretation is again fuzzy, as the ice particles could 

have originated from glacial ice on the volcano slope,

rather than from magmatic water. Note the small

number of cases cited here. Ironically, these observations, which are key for lightning studies, are not made 

systematically for volcanoes. 

6. IMPLICATIONS FOR MICROPHYSICS IN

VOLCANIC CLOUDS 

 The evidence for an abundance of water in all three 

phases in eruption clouds has important implications for

the cloud microphysics occurring therein. Textor et al 

(2003) have already treated some of these processes in

numerical simulations of volcanic clouds. 

 Firstly, the fine volcanic ash particles will serve as 

nuclei for condensation—cloud condensation nuclei for 

the liquid phase of water and ice nuclei for the solid

phase (Mason, 1971; Hobbs, 1975). The high concentrations of such nuclei in volcanic clouds in comparison 

to the concentration of natural aerosol in thunderclouds 

will likely serve to keep the nucleated cloud droplets 

and ice crystals small, thereby suppressing the precipitation process (by either coalescence or by riming). 

Secondly, the classical Bergeron process involving

the liquid and solid phases of water is expected to be

active in the mixed phase region of volcanic eruptions

where the in situ temperature lies between 0o

C and –

40o

C. This process will stimulate the growth of ice 

crystals at the expense of the liquid droplets. 

Thirdly, given the presence of supercooled water

droplets and ice particles, the riming process should

occur for the larger, faster-falling tephra particles, with 

consequent accretion of ice on the surfaces of these

particles, so long as the supercooled droplets are not too

small. In eruptions clouds with extreme updrafts, 

substantially larger than those in thunderclouds, the 

available time for riming is expected to be shorter. 

Nevertheless, the collection action of nucleation and

riming are expected to coat the volcanic particles with 

water substance in ether liquid or solid form, with 

considerable efficiency. This widespread coating of the

volcanic debris would seem to preclude mechanisms for 

charge separation based on tribo-electrification of

silicate mineral surfaces. At least within the mixed 

phase region, often half the depth of the troposphere,

ice particle collisions need to be considered in the 

electrification process.

7. GROSS ELECTRICAL DIPOLE STRUCTURE

OF VOLCANIC ERUPTIONS

A characteristic feature of ordinary thunderstorms is

their gross positive dipolar structure—positive charge

in upper levels and negative charge at lower levels of

the ice region. A weak test of whether ice is responsible for the charge separation in volcanic eruptions is the

inquiry into the gross charge structure of eruptions. 

The available observations summarized in Table 2, 

show gross positive dipole structure and so pass this 

weak test. The test is ‘weak’ because one has a 50-50 

chance of being correct. 

Anderson et al (1965), Surtsey volcano 

“...downwind, there is a region of negative charge beneath 

the region of positive charge.” 

Cobb (1980) Mt. St. Helens volcano 

“the measurements always indicated a positively charged 

plume” 

Hobbs and Lyons (1983), Mt. St. Helens volcano

“negatively charged particles at lower altitudes, and 

positively charged particles higher up” 

Hoblitt (1994), Redoubt volcano

“the flash polarity tended to change through time from 

negative to positive” 

Lane and Gilbert (1992), Sakurajima volcano

“positive charges develop in the gas-rich top and negative 

charges in the ash-rich part of plume” 

Gilbert and Lane (1994), Sakurajima volcano 

“positive charges dominate at the top of the plume and 

negative charges dominate at the base” 

McNutt and Davis (2000), Mt Spurr volcano

“thunderstorms...and eruptions...both show the same 

sequence of first negative, then positive...”

Table 2: Gross Dipole Polarity of Eruption Clouds 

 
Eruptions such as Mt St. Helens in May 1980 (Cobb, 

1980) grow to heights greater than the tallest thunderclouds, and given the foregoing calculations, are

expected to be rich in ice in upper levels. Some of the 

eruption clouds documented in Table 2, however, have

insufficient depth to penetrate the cold part of the 

troposphere, and in this case, their inclusion in the table 

may not be appropriate. It is however useful to consider in this context a meteorological entity composed

of dry silicate minerals—the small vigorous vortices

developing in desert environments called ‘dust devils’. 

The desert conditions typically involve dry air (20%

relative humidity or less), and deep boundary layers in

which condensation and cloud do not occur. There can 

be little doubt that dust devils involve collisions between dry silicate minerals only—no liquid water and

no ice is available. Electrical measurements show that

the gross dipole polarity of dust devils is negative—i.e., 

negative charge in upper levels and positive charge at 

lower levels (Freier, 1960; Crozier, 1964; Ette et al,

1971). Freier (1960) refers to the dust devil dipole as

an ‘inverted thunderstorm’. This dust devil polarity is 

not consistent with any of the results in Table 2, even

for the smaller eruptions (i.e., Sakurajima volcano) that

are most likely NOT to contain ice. 

 The polarity behavior noted for cloud-to-ground

lightning discharges from volcanic eruptions also bears

a similarity with thunderstorms, as noted also in Table 

2. Both Hoblitt (1994) and McNutt and Davis (2000) 

have noted a sequence of activity involving ground 

flashes of negative polarity followed by ground flashes

with positive polarity. This behavior is characteristic of

thunderclouds as they transition from their mature 

phase to their dissipating stage (Moore and Vonnegut,

1977; Williams and Boccippio, 1993). 

8. IMPLICATIONS OF PREDICTIONS FOR THE

SATELLITE-DETECTION OF ERUPTION 

CLOUDS

Satellite remote sensing of volcanic ash clouds has 

focused on the split window technique (Prata, 1989), 

based on the differential infrared response of dry

volcanic ash. Ice is well known to show the opposite 

response (Prata, 1989). Ice-coated ash particles are

expected to respond as ice. Given the calculations in 

the present study, one can expect difficulties with the 

split window technique in distinguishing thunderclouds

from explosive volcanic eruptions. This expectation is

borne out by the observations (Simpson et al, 2000;

Tupper et al, 2004), and in many instances the dry ash 

signature will not appear strongly until the ice near the 

tops of eruptions clouds has sublimated to expose the

dry ash. 

 ‘Dry’ eruptions are referred to in the literature 

(Ellrod et al, 2002), but this is a relative term only. 

Given the water-based physics believed responsible for

explosive eruptions, it is difficult to see how any 

eruption can be dry. Further observations of volcanic 

eruptions with fine time resolution from the earliest

stages are needed to throw more light on this issue. 

9. CONCLUSIONS 

 Calculations have been presented which treat the

transferal of magma water in the Earth to eruptions

clouds in the atmosphere. Volcanic lightning appears

to be widespread, and the high water contents of magmas may be key to electrification processes. Under

favorable assumptions, water in both its condensed

phases is expected to be abundant in large Plinean 

eruptions. Further evidence involving gross electrical

structure and lightning behavior is identified for a

fundamental role for ice and lightning production in 

large eruptions. However, basic information on water

and ice contents in volcanic plumes is poorly known. 

Instrumental electrical data and direct sampling of the 

water contents of ash columns and adjacent atmosphere 

are needed for at least a few case studies. 

REFERENCES 

 The page limitation for this submission did not allow 

inclusion of references. These will be supplied on

request from earlew@ll.mit.edu or 

steve@giseis.alaska.edu. 

ACKNOWLEDGEMENTS 

We appreciate discussions and correspondence on 

these issues with Marcia Baker, Gary Ellrod, Gerald

Ernst, John Ewert, Fred Frey, Jennie Gilbert, Tim 

Grove, Marianne Guffanti, Paul Herzegh, Peter Hobbs,

Rick Hoblitt, Patricia Mothes, Chris Newhall, Scott

Oswalt, Dee Pack, Alex Proussevitch, Carl Rice, Bill

Rose, Danny Rosenfeld, Tom Shaw, Lee Siebert, Tom 

Simkin, Inna Sofonova, Edna Sugihara, Christiane

Textor, Andrew Tupper, Paul Wallace, Richard Waitt, 

Mark Weber and Rick Wunderman. 

This research was supported by FAA’s Oceanic

Weather Program and by the NASA program on Advanced Satellite Aviation Products. We acknowledge 

Gloria Kulesa, Pete Kirchoffer, and John Murray for 

their support. 

 We thank Cynthia Woods and Nancy Bonanno for 

their kind assistance in the processing of the manuscript. 

 
3.1 

Session 3 – Page 1 

MODELING VOLCANIC ASH TRANSPORT AND DISPERSION: 

EXPECTATIONS AND REALITY

René Servranckx and Peter Chen 

Montréal Volcanic Ash Advisory Centre, Canadian Meteorological Centre, 

Meteorological Service of Canada 

FINAGLE’s LAWS OF INFORMATION: 

The information you have is not what you want 

The information you want is not what you need 

The information you need is not what you can obtain 

The information you can obtain costs more than you want to 

pay 

1. INTRODUCTION 

1.1 Finagle’s aphorisms capture the essence of the volcanic 

ash transport and dispersion modeling problem. Forecasting 

accurately the transport of airborne volcanic ash is a complex 

challenge. Yet, improvements in model formulation, a rapid 

increase in computing power combined with 24-hr real time 

monitoring meteorological operations have lead to significant 

improvements in the prediction of airborne volcanic ash. It 

would be unthinkable to operate today without the use of 

volcanic ash transport and dispersion models (VATDM). 

1.2 The aviation community operates in a very precise and 

high accuracy environment. Aircraft flying at high speed are 

separated vertically by only a thousand feet. The time of 

landing thousand of kilometers away can be predicted to 

within a few minutes. This naturally leads users to have high 

expectations for VATDM, given their usefulness and recent 

successes. 

1.3 Users expect VATDM to produce accurate information on 

where ash is or isn’t present both in time and space. As 

importantly, they expect this information to be delivered in a 

timely matter. 

1.4 What do these expectations mean from a modeling 

perspective and, more importantly, can VATDM meet them? 

The objective of this paper is to discuss these points (‘’reality 

check’’), to present some of the limiting factors and to 

suggest some areas for improvement. 

2. BASIC COMPONENTS OF THE PROBLEM 

2.1 In its simplest form, the problem of accurately forecasting 

ash with VATDM can be expressed as having 3 distinct 

components: 

- VOLCANIC ASH SOURCE 

- METEOROLOGY 

- TRANSPORT AND DISPERSION 

2.2 The VOLCANIC ASH SOURCE component comprises 

all non-meteorological parameters that characterize a specific 

eruption or a volcanic ash cloud. For example, the volume / 

mass of ash released in the atmosphere, the duration of the 

eruption, the vertical and horizontal distributions of the ash 

around the volcano or in a detached volcanic ash cloud, the 

base and top of the ash cloud, particle size distribution, etc. 

2.3 The METEOROLOGY component includes all 

meteorological parameters (wind fields, moisture, stability, 

etc.) that are predicted by NWP (numerical weather 

prediction) models. 

2.4 The TRANSPORT AND DISPERSION component 

essentially combines inputs from the previous 2 components, 

though the use of VATDM, to displace and disperse the 

volcanic ash in the atmosphere as well as depositing it at the 

surface using various removal and deposition mechanisms. 

3. TIMELINESS AND ACCURACY 

3.1 Timeliness is the ability to quickly deliver the 

information. Its exact definition varies from one user to 

another according to specific needs. Accuracy is also a 

relative term for the same reasons. Its definition also depends 

on whether the approach is qualitative or quantitative. 

3.2 In the context of aircraft operating at 700 knots, timeliness 

translates to having VATDM guidance delivered in a matter 

of minutes after notification of the eruption. At the same time, 

accuracy means that VATDM are expected to give precise 

and exact information on where ash is or isn’t present in time 

and space. 

3.3 In the context of the operational, real time application of 

VATDM, timeliness and accuracy are equally important for 

aircraft operations. Unfortunately, they are also somewhat 

counter posing. Timeliness implies that the guidance is made 

available quickly. A prerequisite for accuracy is that accurate 

data and information must first be collected and checked 

before being fed to the VATDM. This however takes time. 

3.4 Attaining a balance between timeliness and accuracy is 

not easy. It can however be helped by quickly issuing a first 

run based on whatever information is available initially and 

default source term parameters for the rest. Subsequent runs 

and updates are then done as new information becomes 

available. 

3.5 Putting aside the timeliness issue, it is clear that the 

accuracy of the guidance produced by the transport and 

dispersion component, through the use of VATDM, is highly 

dependent on the quantitative accuracy of the volcanic ash 

source and meteorology components that feed it. In short, an 

accurate quantitative time / space forecast of airborne 

volcanic ash can not be achieved without accurate quantitative 
Session 3 – Page 2 

information from the volcanic ash source and meteorology

components. 

3.6 The expectations for VATDM to produce accurate 

information on where ash is located in time and space can be 

expressed quantitatively in the modeling context in the form 

‘’the volcanic ash concentration at latitude / longitude X in Y 

hours after the start of the eruption will be Z micrograms of 

ash per cubic meters at an altitude of W feet’’. 

3.7 What are the factors that limit or restrict attaining accurate 

quantitative forecasts of airborne volcanic ash? They are 

discussed in the next section. 

4. LIMITING FACTORS

4.1 Some of the limiting factors for the VOLCANIC ASH 

SOURCE component include: 

4.1.1 Eruption parameters are largely unknown and / or 

poorly quantified. This is especially true for the real time 

response but also, in many cases, long after the eruption has 

ended. Large uncertainties exist in the estimate of the total 

amount of ash released, the time and duration of the eruption, 

the vertical and horizontal distribution of the ash. Even the 

height to which the plume rises is at times hard to determine, 

for example when ice or water clouds are present. 

4.1.2 Because many of the world’s active volcanoes are 

located in uninhabited regions, the rapid detection and 

location of volcanic eruptions are often problematic. In this 

regard, and aside from limited monitoring instruments such as 

seismological and infrasound, satellite remote sensing 

techniques (hot spot identification, ash signature, etc.) are 

used. However there are practical problems limiting their 

reliability and coverage (e.g. cloud cover, satellite coverage, 

signal contamination, detection schemes, day versus night 

application, etc). Simply put, the remote sensing instruments 

and tools currently available are not capable of producing an 

accurate quantitative measurement of the 3D space and time 

structure of airborne volcanic ash. Even when data are 

available (for example, estimates of the total volcanic ash 

mass loading estimated from satellite imagery), there is little 

or no information on the vertical distribution. 

4.1.3 Objective measurements (wind tunnel experiments) of 

the threshold concentration at which volcanic ash becomes a 

‘’significant” threat to engines or other components of aircraft 

have not been done. It is likely that the threshold value would 

vary with type of engine and aircraft. From a scientific point 

of view, it would be important to conduct such studies but is 

not clear, from an operational perspective, how this 

information might be used to improve the VATDM, given the 

numerous other remaining uncertainties. 

4.1.4 A report on the brief and inadvertent encounter of a 

NASA DC-8 research airplane with a diffuse volcanic cloud 

35 hours Mt. Hekla, Iceland erupted in February 2000 

provides a fascinating insight on how very low concentrations 

of volcanic ash can apparently still be damaging (Grindle and 

Burcham, 2003). The flight crew noted no change in cockpit 

readings, but the sensitive research instruments onboard the 

plane detected the diffuse cloud of ash and sulfur dioxide. 

During the next 3 days, seven other research flights were done 

in the same region of the Arctic. The sensitive research 

instruments again recorded traces of the volcanic ash / SO2 

cloud but much more diffuse than in the first encounter. 

Subsequent inspections to the plane lead to the removal and 

overhaul of the engines at a cost of $3.2 million. Apparently, 

damage can occur with very little ash. 

4.1.5 Because of uncertainties of the source term, the 

VAACs’ guidance charts err on the side of safety and depict 

hazardous zones relative to low threshold values. This may at 

times overestimate the actual extent of the volcanic ash cloud. 

While this approach is prudent from a VAAC perspective, it 

may be problematic for the Meteorological Watch Offices 

issuing SIGMETs, and equally for the primary users: air 

traffic controllers and the airline companies. Decisions based 

on SIGMETs, while primarily for safety arguments, can also 

have major economic and other operational implications. 

4.1.6 The criterion for displaying volcanic ash on the 

guidance charts is based on a ''visual ash cloud'' (ICAO, 

1998). Yet, there is no quantitative or scientifically-based 

definition of what constitutes a visual ash cloud. This problem 

has been raised on a number of occasions, including 

international meetings, but there is no simple way of defining 

it. A visual ash cloud as sighted by a pilot may be different 

from that detected by a satellite or predicted by a model. 

Even with an objective definition of ‘’visual ash cloud’’, it is 

very likely that a single value for all situations would not 

exist. For a specific situation, the value is likely to change 

also in time and space. This is especially true for a long lived 

event where the atmospheric transport would disperse the ash 

over a large domain. Forecasters can play with contouring of 

the predicted ash plume or use "ash reduction" schemes for 

the model source term eruption parameters. The VAAC 

meteorologist can also adjust the threshold value defining the 

model output ash plume and the corresponding contouring on 

the charts based on real time data. Unfortunately, these 

modifications may at times introduce additional uncertainties 

and complications for non-specialist users trying to interpret 

the ash charts. 

4.1.7 Eruption heights are often reported in flight levels given 

its general use by the aviation community. Flight levels are 

based on what is know as the ‘’standard atmosphere’’ and rely 

on a number of assumptions. Because of this, there can be 

significant differences between the flight level reported by an 

aircraft and the true height with respect to the ground or sea 

level. 

4.2 For the METEOROLOGY component, some of the 

limiting factors are: 

4.2.1 The horizontal resolution of Numerical Weather 

Prediction (NWP) models typically range from a few 

kilometers for a limited domain / high resolution model to 100 

kilometers for global models. 

4.2.2 NWP models use a certain number of discrete levels 

(typically in the range 25 to 60) to represent the vertical 

component of the atmosphere. This means that meteorological 
Session 3 – Page 3 

parameters at a level other than the model levels have to be 

deduced in one way or another (interpolation, averaging of 2 

model levels, etc). Also, there are more levels in the lower 

portion of the atmosphere. Typically, half of the levels or so 

are found below 600 hPa. 

4.2.3 The fundamental vertical coordinate of most NWP 

models is pressure (SIGMA and ETA coordinates). The 

conversion of the wind and temperature fields to flight levels 

or heights is based on a number of assumptions that have 

limitations. 

4.2.4 The earth's surface features (topography) in NWP 

models are adjusted to a scale that is consistent with the 

horizontal and vertical resolution of the models. A very high, 

steep mountain will therefore be represented as a smoothed, 

rounder and flatter surface in the NWP model topography. 

This of course depends on the specific resolution of a model 

but, as a general rule, there are always differences between 

reality and what the model sees. A concrete, but somewhat 

extreme example of this: the topography of the Regional 

GEM model of the Meteorological Service of Canada for one 

of its recent operational configurations (24 kilometers 

horizontal resolution; 28 vertical levels) had its highest 

surface point in Alaska at 2640 meters. Yet in reality the 

highest peak, Mount McKinley, reaches 6194 meters! 

4.2.5 Accuracy of the predicted fields: Our knowledge of the 

initial conditions in the atmosphere is incomplete due to a 

number of factors (limited observational data, errors in 

measurements, data cut-off deadlines, etc). We are faced with 

the problem of creating a sufficiently accurate picture of the 

state of the atmosphere at the outset of the forecast process. 

Errors introduced at the beginning of the forecast will 

propagate and amplify at each forecast interval, gradually 

eroding its accuracy and usefulness. In some situations, a 

small difference in the initial atmospheric conditions can 

produced significant differences in the forecasts. While NWP 

models are generally quite good in their predictions for the 

initial 24 to 48 hours, some atmospheric flows and patterns 

are much harder to predict accurately than others. 

4.2.6 Another area of errors in NWP models results from a 

type of approximation called ‘’parameterization’’. It can be 

defined as the representation, in a dynamic model, of physical 

effects in terms of admittedly oversimplified parameters, 

rather than realistically requiring such effects to be 

consequences of the dynamics of the system. It is done to take 

into account the large-scale effects of phenomena that are too 

small to be picked-up at the model's resolution or too complex 

to be represented exactly. For instance, individual 

thunderstorms are too small to be forecasted by the model; yet 

in order to be useful the model must still produce a good 

approximation of the effects of thunderstorms on large-scale 

precipitation and temperature patterns. To be successful, the 

model must integrate an understanding of many different 

phenomena and their interactions: wind fields; how energy 

received from the sun is absorbed and transformed by oceans, 

the ground, the air, and the clouds; how water vapor 

condensates into clouds and how droplets of water turn to 

rain, ice and snow; etc. Thus, errors in handling one type of 

phenomenon can propagate to other parts of the model, or 

amplify errors in other model sub-systems. 

4.3 Limiting factors for the TRANSPORT AND 

DISPERSION component: 

4.3.1 The limiting factors presented in sections 4.1 and 4.2 

have a clear, direct and important influence on the accuracy of 

the transport and dispersion component. Many of the factors 

previously covered also apply to the transport and dispersion 

component. They will not be repeated here. 

4.3.2 At the same time, VATDM also have limiting factors 

that can be considered as quasi-independent from the source 

term and meteorology components. For one, VATDM must 

formulate the source term in one way or another. Even if the 

source term parameters were perfectly known, the VATDM 

formulation of the source term would have to be 

parameterized. 

4.3.3 Another limiting factor is that the VATDM, for a 

number of reasons, often operate on space / time grids that are 

different from the ones used by the NWP models. This 

involves a number of interpolations. 

4.3.4 Wind fields contribute largely to the horizontal transport 

airborne volcanic ash but parameterization must be used to 

account for the dispersal, removal and deposition of ash in 

time and space. 

4.3.5 Real time assimilation of airborne ash plume data is not 

done by models. This would improve the tracking of ash 

movement and spreading over longer time spans. The data 

assimilation techniques are routinely used for other 

meteorological variables such as wind, temperature and 

pressure. However, the problem of volcanic ash is more 

complex and quite similar to total ozone data assimilation. 

The problem is also compounded by the absence of 

quantitative data on the vertical and horizontal space and time 

structure of the ash cloud. Given the important differences in 

wind speed as a function of altitude, this vertical distribution 

is, in fact, critical to operational decisions. 

4.3.6 The ability of VATDM to predict accurately is also 

dependent on actual atmospheric circulation and flow into 

which the volcanic ash is injected. Some flows will be 

conducive to maintaining an integral ash cloud for many days 

and hence at great distances from the eruption. These are 

likely to be easier to forecast. 

4.3.7 Another factor to consider is how information is 

presented to the users. Many operational constraints restrict 

the type and amount of information that can realistically be 

provided, especially in real time. This is important because 

how one interprets information is highly dependant on a 

number of factors, including the tools and technology 

available to display the information, how the information is 

presented and how one looks at the information. 
Session 3 – Page 4 

 

4.3.8 To 

illustrate this, we 

present two 

examples. First 

look at the image 

on the right and 

note how your 

perception of 

what it shows is 

changed once 

you start looking 

for faces 

(www.banane.be/images.php). As another example, we look 

at some Canadian Emergency Response Model images 

showing the ‘’visual ash cloud’’ 45 hours after the start of the 

Mt Cleveland Alaska eruption in February 2001. The 3 

images are based on identical conditions for the volcanic ash 

source, the meteorology and the dispersion / transport 

(Simpson et al, 2001). The only difference is the threshold 

value to display the ‘’visual’’ ash cloud boundary. The units 

are indicated on each image, in micrograms per cubic meter 

average volcanic ash concentration for the layer 20 to 35 

thousand feet. Note how the perception of where ash is or is 

not present changes wit the display threshold. 

 

5. DISCUSSION / AREAS FOR IMPROVEMENT

5.1 The large number of uncertainties and limitations 

described in Section 4 may lead one to have doubts about the 

usefulness of the VATDM guidance. These are not founded. 

The qualitative verification of VATDM guidance based on 

satellite data and other tools has shown it to be of great value. 

5.2 It would be unthinkable to operate today without 

VATDM. This is particularly true in an operational, real-time 

response context where timeliness in the delivery of the 

guidance is of key importance. Also, at times, the only 

guidance available is the one provided by VATDM. For 

example, we may not be able to detect volcanic ash with 

satellites when meteorological clouds are present. Also, 

satellite data may not be available in the area in interest. 

5.3 The limitations also point out the importance of not using 

the guidance blindly. A careful interpretation of the guidance 

must be done by the user and this can not be done without a 

good knowledge of the limitations. 

5.4 VATDM guidance and remote sensing techniques must be 

used together. Each can benefit from information provided by 

the other. But in addition, their simultaneous use is synergetic 

and sometimes even synergistic. For example, satellite data 

can help to better define what concentrations should be 

displayed on VATDM guidance while VATDM can help 

remote sensing detection by pointing out where ash is likely 

to be found. This synergy has been demonstrated on a number 

of occasions. 

5.5 Clearly, any improvement that might reduce the 

uncertainties and limitations listed in section 4 would be 

beneficial. Listed below are some of the key elements that 

should be considered in order to maximize the improvements 

in VAFTD guidance: 

5.5.1 Source term – eruption parameters: The reports of the 

Second and Third International Workshop on Volcanic Ash 

(Toulouse, May 1998 and September 2003) indicated that 

substantial improvements could be made in VATDM 

guidance if the source term estimates were improved. The 

basic question remains: is it possible to produce quantitative 

estimates of the source parameters for a specific eruption 

based on historical events, types of volcanoes, etc? What 

about the amount of ash released, the vertical and horizontal 

distributions, the particle size distribution, etc.? We seek the 

expertise of volcanologists to help answer these questions. If 

quantitative estimates can not realistically be produced, 

VATDM will simply continue to use some default 

parameters. A clear answer to these questions would help 

bring some closure to the subject. 

5.5.2 Source term and Transport / Dispersion: The NASA 

DC-8 plane encounter with a diffuse volcanic cloud points to 

the fact that very small ash concentrations can produce 

damage and highlights he importance of a better definition of 

the source term. The encounter provides another example of a 

long-lived volcanic cloud. From a modeling perspective, it 

raises the question of how far out into the future can VATDM 

predictions be still considered reliable - even if the 

meteorological inputs have been updated along the way. For 

the purpose of immediate alerting, perhaps this is irrelevant. 

But if unconditional ash-avoidance is the rule, predictions 

beyond 72-hours would still be relevant - i.e. as long as there 

is ash, there should be an interest. Obviously, the predictions 

could be made over longer time periods and with more 

reliably / credibly if we could assimilate airborne ash 

information. 

5.5.3 Source term - Remote sensing and detection of ash: Any 

technological advancement that might lead to a better 

quantitative estimate of airborne volcanic in the horizontal 

and vertical would have great benefits for VAFTD. 

5.5.4 Source term – Assimilation of volcanic ash data: Some 

exploratory work on volcanic ash assimilation has already 

been done. For example, Siebert et al. 2002 used the basic 

idea that the vertical wind shear in the atmosphere (e.g. 

change of wind speed and / or direction with height) leads to 

different transport paths of the cloud (or parts of it) at 

different initial heights. The movement of the ash cloud 

diagnosed from satellite data and images could then 

1 10 100
Session 3 – Page 5 

possibility be used to infer its vertical displacement and 

hopefully even a vertical distribution. Exploratory work is 

also being done elsewhere, for example at the NOAA Air 

Resources Laboratory. How much can be achieved in this area 

is highly dependant on improvements in the area of remote 

sensing (section 5.5.3). The reality is that real-time 

assimilation of volcanic ash data in a meteorological analysis 

using an objective numerical procedure remains a complex 

problem that will not be solved quickly. 

5.5.5 Meteorology – NWP models: The improvement of NWP 

models is an ongoing process. Major NWP Centers regularly 

implement operational modifications to their analyses and 

forecast systems as a result of advancements in the areas of 

remote sensing, data assimilation, parameterization, 

computing power, etc. The vertical, horizontal and temporal 

resolutions of NWP models are also increased on a regular 

basis. 

5.5.6 Meteorology and Transport / Dispersion – Ensemble 

forecasting: We already discussed the fact that the guidance 

skill diminishes with forecast time because of the growth of 

inevitable uncertainties in the initial conditions, and because 

numerical models describe in only an approximate way the 

exact laws of physics. Ensemble Forecasting provides a 

practical tool for estimating how these errors could affect the 

guidance. The basic principle is to produce many runs with 

NWP models and / or VATDM, using slightly different initial 

conditions to simulate errors in measurements, different 

parameterization schemes, etc. The results of the ensemble 

members are then averaged. It has been shown that this way 

of proceeding produces better guidance than what is obtained 

by looking at the results of a single model run. Furthermore, a 

measure of confidence in the average can be obtained from 

what is called the ‘’spread’’ of the ensemble. It is a measure 

of how similar or different the various members (i.e. runs) 

are. A small spread indicates that the runs are similar while a 

large spread signals large differences. This is important 

because we know that the accuracy of the guidance is greater 

when the ensemble spread is small. Ensemble forecasting is 

already done operationally by major National Weather 

Centers in the area of NWP models but has not been yet 

attempted for VATDM. This might be an interesting avenue 

to explore. At the same time, the timeliness question would 

also need to be evaluated if ensemble forecasts were done, 

given that many runs need to be executed. 

6. CONCLUSION 

This paper presented the main factors that influence and 

sometimes limit VATDM. Despite the limitations and 

uncertainties, VATDM have proven to be of great value, to 

the point where it would be unthinkable today to operate 

today without them. At the same time, users must be aware of 

the limitations when using VATDM outputs. Another 

important point is that VATDM can not be used blindly. In 

fact, there is a synergistic benefit in using VATDM in 

conjunction with other sources of information. 

REFERENCES 

ICAO, 1998: International Civil Aviation Organization 

International Standards and Recommended Practices - 

Meteorological Service for International Air Navigation - 

Annex 3 to the Convention on International Civil Aviation 

(July 1998), 92 pp. 

Grindle, T.J. and F. W. Burcham, 2003: Engine Damage to a 

NASA DC8-72 Airplane from a High-Altitude Encounter 

with a Diffuse Volcanic Ash Cloud. NASA/TM-2003-

212030, August 2003, 27 pages. 

(www.dfrc.nasa.gov/DTRS/2003/PDF/H-2511.pdf) 

Siebert, P., A. Frank and R. Servranckx, 2002: Satellite 

Data Assimilation for Volcanic Ash Forecasts. Poster 

presented at the European Geophysical Society 

General Assembly, Nice, France, April 2002. (A PDF 

version is available on request). 

Simpson, James J., Hufford, Gary L., Pieri, David, 

Servranckx, René, Berg, Jared S., Bauer, Craig: The 

February 2001 Eruption of Mount Cleveland, Alaska: 

Case Study of an Aviation Hazard, Weather and 

Forecasting 2002 17: 691-704. 
3.2 

Session 3 – Page 7 

DISCREPANCIES BETWEEN SATELLITE DETECTION AND FORECAST MODEL 

RESULTS OF ASH CLOUD TRANSPORT: CASE STUDY OF THE 2001 ERUPTION OF MT. 

CLEVELAND VOLCANO, ALASKA 

David J. Schneider, USGS-Alaska Volcano Observatory, Anchorage, AK, USA 

Rene Servranckx, Environment Canada, Montreal VAAC, Montreal, Canada 

Jeff Osiensky, National Weather Service, Anchorage VAAC, Anchorage, AK, USA 

Volcanic ash transport and dispersion models are used in conjunction with satellite image data to forecast 

the movement of potentially hazardous volcanic ash clouds. Although these sources of information 

typically agree, discrepancies do occur. These discrepancies cause difficulty in accurately forecasting ash 

movement, especially in cases wherein model results indicate the presence of ash but none is detected in 

satellite data. A case study of the February 19, 2001 eruption of Mt. Cleveland volcano, Alaska is 

presented utilizing results from the CANERM dispersion model and GOES satellite images. For this 

eruption, the extent of volcanic ash predicted from ash transport and dispersion models was much larger 

than the extent detected in satellite image data. A discussion of the operational forecast decisions and 

information releases that were made during this eruption will illustrate the challenge faced in these 

instances: Whether to issue warnings based solely on model results or solely on satellite data. 
3.3 

Session 3 – Page 9 

ASSESSING VOLCANIC ASH HAZARD BY USING THE CALPUFF SYSTEM 

Sara Barsotti(1), Augusto Neri(1), and Joe Scire(2)

(1) Centro di Modellistica Fisica e Pericolosità dei Processi Vulcanici, 

Istituto Nazionale di Geofisica e Vulcanologia, via Della Faggiola 32, 56126 Pisa, Italy 

(2) Earth Tech Inc., Concorde, MA USA 

1. Introduction 

Nowadays the presence of volcanic ash in the 

atmosphere represents a serious risk for the aviation. 

A large number of volcanoes is indeed situated near 

main commercial and civil air routes; for examples 

the regions of North-West America, Alaska, and the 

Kamchatka Peninsula. In Europe, the problem is 

probably less relevant than in other parts of the 

world. However, just in the last few years, the 

explosive activity of Mt.Etna, Sicily (Italy), has 

focused the attention of volcanologists and air traffic 

operators to the problem of an active volcano located 

very close to two international airports (Catania and 

Sigonella) as well as to the city of Catania and many 

other towns. 

Although this problem has drawn the attention of the 

scientific community for many years, a reliable 

instrument for forecasting ash cloud movements and, 

therefore, for avoiding plane encounters does not 

exist yet (Williamson, this issue). To this aim a 

number of computer codes able to describe the 

temporal and spatial evolution of the ash plume have 

been developed worldwide in the last 15 years. Some 

of them are actually in use at the Volcanic Ash 

Advisory Centers (VAACs), such as CANERM 

(which is operative at the Canadian Meteorological 

Centre), MEDIA (operative at Toulouse Meteo 

France), NAME (operative at London Met Office) 

and VAFTAD (developed by NOAA ARL and in use 

at the Washington and Anchorage VAACs). 

CANERM (Simpson et al., 2002) is a 3D Eulerian 

model used for medium- and long-range transport 

which assumes a virtual source described by a 

distribution of mass in the vertical direction. 

Similarly, MEDIA (Piedelievre et al., 1990) is an 

Eulerian atmospheric transport/diffusion model 

focused on the long-range dispersal of particles 

ejected from a source at a given altitude. Vice versa, 

NAME (Watkin et al., this issue) is a Lagrangian 

particle model that can work on either regional or 

global scales and is able to consider areal as well as 

point-like sources. Finally, VAFTAD (Heffter and 

Stunder, 1993) is a 3D time-dependent Eulerian 

model which needs the maximum height reached by 

the volcanic column to model the source, as input. In 

addition to those used at the VAACs a few more 

models have been developed for or applied to the 

problem of volcanic ash. For instance, the wellknown model PUFF, (Searcy et al., 1998), currently 

used at the University of Tsukuba (Japan) in 

collaboration with the Japan Meteorological Agency 

and at the U.S. National Weather Service, Alaska, 

describes the movements of a collection of discrete 

ash particles representing a sample of the eruption 

cloud by using a Lagrangian scheme and treating the 

source as a virtual pre-assigned vertical distribution 

of mass. Similarly, HYSPLIT (Draxler and Taylor, 

1982, Draxler and Hess, 1998), developed at the 

NOAA Air Resources Laboratory describes, by a 

Lagrangian approach, the evolution of puffs 

(containing material particles with diameters up to 

30μm) without taking account of buoyancy effects. 

Finally, FALL3D (Costa and Macedonio, this issue), 

is an Eulerian advection/diffusion code, developed at 

Osservatorio Vesuviano-INGV, that uses a virtual 

point-like or vertical source of mass on air, and that 

was specifically designed for the estimation of in-air 

ash concentration and ground deposition at medium 

and long distances from the source. 

From such a brief summary it is clear how most of 

the dispersal models in use are relevant only to 

medium- and long-distance dispersal areas and do not 

account for the influence of volcano orography on the 

wind flow field. In addition, none of the above 

models describes the dynamics of the buoyant 

volcanic plume thus making the definition of the 

virtual source quite subjective. 

The aim of this work is to present a new modelling 

system, called CALPUFF, able to describe the 

movements of the ash cloud, as well as the in-air ash 

concentration and ground deposition, generated by a 

given source (Scire et al., 2000). As several other 

codes used in volcanological applications, CALPUFF 

has been originally developed as an air quality 

modelling code for transport of pollutants and then 

applied to several other environmental problems. The 

CALPUFF System is composed of three main parts; 

the geophysical pre-processor, the meteorological 

processor (named CALMET) and the Lagrangian 

dispersal model (named CALPUFF). The dispersal 

model treats the ash cloud as a discrete series of 

packets of particles, or puffs, which are advected by 

the prevailing winds and, at the same time, diffuse in 
Session 3 – Page 10 

the atmosphere. In addition, CALPUFF is able to 

describe the dynamics of the rising buoyant plume, 

and therefore the altitude of the virtual source, 

through the solution of a full non-Boussinesq form of 

the transport equations. Finally, CALPUFF can 

describe the ash dispersal dynamics using very 

refined computational grids (with a final resolution 

up to 1 km or less), while keeping the execution time 

very short (of the order of minutes). In the following 

sections the main features of the system and a first 

application to a real eruption will be presented. 

2. The CALPUFF System 

With the terms “CALPUFF System” here we mean 

the whole numerical procedure that from 

meteorological and geophysical input data computes 

the concentration of the ejected material in the 

atmosphere and at the ground. The CALPUFF system 

was developed by the Earth Tech Inc. in the ‘90 and 

it is available on line at the website 

http://www.src.com/calpuff/calpuff1.htm. CALPUFF 

is a quite complex model composed of a great 

number of sub-processors. Figure 1 shows the basic 

configuration of the modelling system as we have 

used it in our study. The procedure starts with the 

elaboration of the geophysical information, as terrain 

elevation and land-use data. This procedure is run 

only once after the choice of the computational 

domain is made. The geophysical data are then 

processed by two different programs in order to make 

them readable to another pre-processor (named 

MAKEGEO) that merges all the data and produces a 

single geophysical file for the meteorological 

processor CALMET. 

In parallel with the elaboration of the geophysical 

data, the processing of the meteorological data occurs 

in order to provide CALMET of the necessary input 

data every three hours. The meteorological processor 

CALMET is a diagnostic code; this means that it 

computes the values of the meteorological variables 

on a finer grid without solving the time-dependent 

equation of motion. CALMET, in particular, works 

on two steps that refine and correct an initial guess 

field typically provided by a prognostic code. In the 

first step the initial data are interpolated on a grid 

usually much finer than the one used in the mesoscale 

models and the effects of the local orography are 

accounted for. In the second step, data collected at the 

ground or at upper air stations, when available, are 

considered in order to correct the computed wind 

field through an objective analysis that assigns 

appropriate weight to each data. The output provided 

by CALMET contains the wind field and the other 

micro-meteorological variables hourly and on a grid 

in a terrain-following coordinate system with a 

vertical and horizontal user-defined resolution. This 

file, together with the one containing the data related 

to the source, is fed as input to the core of the system: 

the CALPUFF dispersal model. 

This is a Lagrangian dispersion code that treats the 

emitted material as a sequence of puffs each 

containing a discrete quantity of particles. Each hour 

a finite number of puffs are emitted and subjected to 

wind advection, vertical and horizontal diffusion and 

removal of material due to gravity as well as wet 

deposition. The user is then free to define a grid of 

receptors or choose discrete receptors at which 

concentration and ground deposition will be 

calculated. Before illustrating the way in which the 

code computes the ash concentration at a given 

receptor the treatment of the buoyant plume leaving 

the crater is briefly described. 

CALPUFF is indeed able to handle an areal source 

which emits in the atmosphere hot material under the 

action of inertia and buoyancy. To this aim the code 

solves, each hour of simulation, the three equations of 

conservation of mass (eq.(a)), momentum (eq.(b)) 

and energy (eq.(c)) here expressed as (refer to the 

original work of Hoult and Weil (1972) for a detailed 

description of them): 

) 2 | cos | 2 | sin | 2 (ρ αρ φ βρ φ a Ua r a Usc Ua r r Usc ds

d = − +

 (a) 

( ) ( )

( ( ))

2 2

2 2

ρ ρ ρ

ρ ρ

= −

− = −

sc a

a

sc a

U r w gr ds

d

dz

dU U r u U r w dsd

 (b) 

2 2 ( )) 2 ( r

pc

Q wr dz

a d a r T T Usc ds

d − = + η ρ ρ

 (c) 

Figure 1. The flowchart of the CALPUFF System as 

used in our simulations. 
Session 3 – Page 11 

At this stage, only the hot gas of the plume has been 

considered in the above equations; this assumption 

will be removed in the future when the presence of 

particles will be explicitly considered. The code can 

also treat the case of non-steady emission of ash from 

the crater once an input file containing all the 

temporal variations of the source variables is 

provided. 

Once the plume has reached its maximum height the 

puff description begins. At the emission point, 

localized at a given downwind distance from the vent 

and at an effective height above the ground as 

computed by the above described source model, the 

pyroclastic material is released as a series of puffs 

whose dynamics are described in a Lagrangian way. 

During one sampling time step (the time interval at 

which the ash concentration is computed) the puff 

diffuses and its contribution to the concentration at 

each receptor defined is calculated. The mathematical 

expression of this contribution is the following 

Gaussian function corrected to account for vertical 

and horizontal diffusion as well as for gravitational 

settling (Scire et al., 2000): 

exp[ /(2 )]exp[ /(2 )] 2

2 2 2 2

a x c y

x y

g d d Q C σ σ

πσ σ = − −

 (d) 

The quantity of mass in the puff is represented by the 

variable Q and it varies with time because of the 

removal of material due to gravity. CALPUFF 

permits to describe the behaviour of different 

granulometric classes characterized by different 

diameters, densities, and, of course, settling 

velocities. However, the present version of 

CALPUFF is limited to the consideration of particles 

up to a few tens of microns. In eq. (d), da and dc are 

the downwind and crosswind distances between the 

puff centre and the receptor, g is the so-called vertical 

term that takes into account the vertical diffusion due 

to the mixing lid, and the two sigmas represent the 

horizontal diffusion due to turbulent atmospheric 

motions, buoyancy and lateral dimension of the areal 

source. 

Finally, it is worth noting that the CALPUFF System 

has been validated through extensive comparison of 

model predictions to experimental data such as the 

Cross-Appalachian Tracer Experiment (CAPTEX). 

Due to the very good performance of the model, the 

U.S. Environmental Protection Agency (Scire et al., 

2000) has proposed the CALPUFF modelling system 

as a guideline model for regulatory application 

involving long-range transport and in-near field 

applications where non–steady-state effects may be 

important. 

3. A first CALPUFF application to Mt.Etna, 

Sicily, Italy 

A first application of the CALPUFF System, as it 

stands at this time, to a recent eruption of Mt. Etna 

has been carried out in order to a preliminary 

assessment of the capabilities and limits of the code. 

As a consequence this application has to be 

interpreted just as a first step of the research work we 

have planned in order to develop an appropriate 

version of CALPUFF System to be used for volcanic 

purposes. 

The eruption of Mt. Etna we refer to started on 18th

July 2001 and produced a quite intense explosive 

activity for about one week. This activity was 

characterized by an almost continuous injection of 

ash and lapilli in the atmosphere with the formation 

of ash columns up to about 5 km (Coltelli et al., 2001; 

Coltelli, this issue). As mentioned above, the ash and 

lapilli blanketed the city of Catania, producing major 

problems to the city airport, whereas the finer 

particles reached the coasts of Africa. The evolution 

of the ash cloud was closely observed and many 

satellite images are available for a first comparison 

with the model predictions. 

3.1. Input data and computational parameters 

Geophysical, meteorological, and source data were 

defined in order to carry out the dispersal predictions. 

Geophysical data were adopted from USGS. In detail, 

GTOPO global data and global land-use data with a 

resolution of about 900 m were implemented. SRTM 

data for terrain elevation were also implemented 

producing very similar results. As far as the 

meteorological data, two different datasets were used: 

one provided by NOAA and the other one by 

ECMWF. Both datasets had a spatial resolution of 

2.5*2.5 degrees and a temporal resolution of 6 hours 

(both of them were produced by reanalysis studies). 

This double choice was actually due to our interest in 

investigating the sensitivity of CALPUFF results on 

meteorological data. Finally, in Table 1 are reported 

the vent data used as input data and boundary 

conditions for the solution of eqs. (a)-(c) as well as 

the main puff parameters. 

The computational domain is composed by 100*100 

cells with a grid spacing of 2km and twelve vertical 

levels not uniformly spaced. It should also be noted 

that, so far, we have used CALMET in a noobservational mode, i.e. skipping the objective 

analysis described above. 
Session 3 – Page 12 

Table1. Vent input data and puff parameters as 

used in the simulations (Coltelli et al., 2001, 

IAVCEI 2004). 

Vent velocity 25-75 m/s 

Vent temperature 100-300 °C 

Vent radius 25-75 m 

Ground elevation 2550 m 

Vent height a.g. 100 m 

Emission rate 10^5 kg/s 

Particle diameter 3-64 μm 

Particle density 2500 kg/m^3 

3.2. Main results 

The following aspects of the dispersal process have 

been investigated by simulating the eruption over five 

days (starting at 00UTC 20th till 24UTC 24th of 

July): 1) the main large-scale features of the 

dispersal, 2) the sensitivity of results on the 

meteorological datasets used and 3) the model 

capability of describing the rising phase of the plume. 

Model results, shown in form of animations, clearly 

describe the temporal evolution of the ash cloud that 

results to be mostly affected by the wind direction at 

the level of puff emission. The predicted dispersal 

direction is for long period consistent with 

observations. With full particular, observations 

indicate that, for all the 20th of July, the plume is 

directed in the N-E direction whereas it moves in the 

S-E direction for the remaining days interesting 

repeatedly the city of Catania and the Fontanarossa 

Airport. In addition, in the early morning of July 22 a 

plume bifurcation, which disappeared within few 

hours, was observed in satellite images. 

Figure 2 shows an example of comparison between 

model predictions and observations with satellite 

images. Plots (a) and (b) refer to 11UTC of July 20, 

whereas plots (c) and (d) refer to 1130UTC of July 

22. All plots show the cumulative concentration 

(kg/m3

), integrated over the vertical levels, as 

calculated by CALPUFF. In particular, plots (a) and 

(c) were generated using NOAA data, whereas plots 

(b) and (d) were generated using the ECMWF data. 

From the figure it is evident that the comparison is 

quite good for both datasets even though, for July 20, 

the data provided by ECMWF seem to produce 

results which agree more with the observations. In 

this case, a deeper analysis of the meteorological 

conditions showed that, even though at that time the 

heights of puff emission were very similar, some 

hours before, the difference in wind direction in 

correspondence with the emission heights was about 

30 degrees. 

The dynamics of the rising plume was also analysed 

due to its importance in the determination of the puff 

emission point. In particular, the temporal evolution 

of the effective height and the downwind distance of 

the emission point from the vent was investigated. 

Results showed that these two variables are strictly 

related - when one increases the other decreases - and 

strongly depend on meteorological conditions such as 

the mixing layer depth (that in turn depends on the 

hour of the day). 

Finally, by using an appropriate set of receptors it 

was possible to investigate the spatial and temporal 

distributions of ash concentration in the atmosphere. 

In particular, the horizontal and vertical distribution 

along the dispersal axis was analysed. It was found 

that, even at constant emission rate, the observed 

variability, in time and distance from the vent, of the 

maximum ash concentration is strongly affected by 

Figure 2. Comparison between CALPUFF modelling results and satellite images on 

 July 20 (top) and July 22 (bottom).The first column refers to the NOAA meteo data, the second 

column to the ECMWF meteo data. 

The minimum value chosen for the graphic is equal to 10^-7 kg/m^3
Session 3 – Page 13 

the temporal movements of the emission point as well 

as by the meteorological conditions and the turbulent 

processes that control the ash diffusion. 

4. Conclusive remarks 

In the light of the above described modelling 

capabilities and results obtained from its first 

volcanological application, the CALPUFF modelling 

system appears to be a very promising tool for the 

real-time monitoring and forecasting of ash dispersal 

dynamics produced by a weak plume. The possibility 

to describe the dynamics of the rising plume, to 

account for the volcano topography and direct 

measurements of meteorological conditions, to work 

with a user-defined spatial resolution, to obtain 

results in near real-time, are some of its more 

attractive features. In addition, the ability of 

reproducing correctly the large-scale evolution of the 

ash cloud movements underlies the efficiency of the 

meteorological processor CALMET in generating a 

reliable wind field even using a low resolution 

meteorological input data. However, the sensitivity 

analysis on the meteorological dataset highlights the 

importance of using high-resolution meteo data, as 

well as an accurate description of plume rise, in order 

to get a correct prediction of ash dispersal. Future 

works should also focus on the extension of the code 

to the modelling of coarse ash and lapilli in order to 

describe the more proximal fallout. 

Finally, it is worth mentioning that an effective 

progress in the modelling and forecasting of ash 

dispersal appears strictly tied to the definition of 

accurate volcanological datasets to be used in model 

validation studies as well as to the carrying out of 

real-time measurements of the plume. 

Acknowledgements 

This work has been partially supported by 

Dipartimento di Protezione Civile, Gruppo Nazionale 

per la Vulcanologia, Italy, Framework Programme 

2000-2003, project no. 9, and by Ministero 

dell’Istruzione dell’Università e della Ricerca, Italy, 

FIRB project no. RBAU01M72W. 

References 

Coltelli M., 2004: Recent Etna’s explosive eruptions 

threaten seriously aviation in central Mediterranean 

region, Proc. 2nd International Conference on 

Volcanic Ash and Aviation Safety. 

Coltelli M., Del Carlo P. and Macedonio G., 2001: 

The plume of the 2001 eruption of Etna: observation, 

modelling and impact on Catania airport operations, 

Proc. Assemblea Generale del Gruppo Nazionale per 

la Vulcanologia. 

Costa A. and Macedonio G., 2004: FALL3D: A 

numerical model for volcanic ash dispersion in the 

atmosphere. Proc. 2nd International Conference on 

Volcanic Ash and Aviation Safety. 

Draxler R.R. and Taylor A.D., 1982: Horizontal 

dispersion parameters for long-range transport 

modelling, J. Appl. Met., 21, 367-372. 

Draxler R.R and Hess G.D., 1998: An overview of 

the HYSPLIT_4 modelling system for trajectories, 

dispersion and deposition, Austral. Meteorol. Mag., 

47, 295-308. 

Heffter J.L and Stunder B.J.B., 1993: Volcanic ash 

forecast transport and dispersion (VAFTAD) model, 

Weath. Forecast., 8, 533-541. 

Hoult D.P. and Weil J.C., 1972: A turbulent plume in 

a laminar crossflow, Atmos.Environ., 6, 513-531. 

IAVCEI Tephra Group webpage 2004: 

www.soest.edu/IAVCEI-tephra-group/. 

Piedelievre J.P., Musson-Genon L. and Bompay F., 

1990: MEDIA- An Eulerian model of atmospheric 

dispersion: a first validation on the Chernobyl 

release, J. Appl. Meteor., 29, 12, 1205-1220. 

Scire J., Strimaitis D.G. and Yamartino R.J., 2000: 

CALPUFF user's guide. 

Searcy C., Dean K. and Stringer W., 1998: PUFF: a 

Lagrangian trajectory volcanic ash tracking model, J. 

Volcanol. Geotherm. Res., 80, 1-16. 

Simpson J.J., Hufford G.L., Servranckx R., Berg J.S. 

and Bauer C., 2002: The February 2001 eruption of 

Mt. Cleveland, Alaska: Case study of an aviation 

hazard, American Meteorol. Soc., 17, 691-704. 

Watkin S., Ryall D., Watkin H., Champion H., 

Wortley S. and Gait N., Volcanic ash monitoring and 

forecasting at the London VAAC, Proc. 2nd

International Conference on Volcanic Ash and 

Aviation Safety. 
3.4 

Session 3 – Page 15 

POTENTIAL OF THE ATHAM MODEL FOR USE IN AIR TRAFFIC SAFETY 

1

Christiane Textor, 2Gerald GJ Ernst, 3Michael Herzog, 4Andrew Tupper 

1 Lab. Sciences du Climat et de l’Environnement, CEA-CNRS, Paris, France 2 Geological Institute, University of Ghent, Krijgslaan 281/S8, B-9000 Gent, Belgium 3 Dept. of Atmospheric, Oceanic, and Space Sciences, University of Michigan, Ann Arbor, USA 4 Bureau of Meteorology, Darwin, Northern Territory, Australia, and School of Mathematical Sciences, 

Monash University, Victoria, Australia

Abstract

Numerical models used by the VAAC centers often 

fail to accurately predict volcanic ash dispersal, because they do not include sufficient information on 

the initial ash distribution in the proximity of the 

volcano. In addition, ash dispersal is assumed to be 

determined by the atmospheric background conditions only, and effects of the eruption on the ambient 

motions are neglected. 

In this paper we present the eruption column model 

ATHAM (Active Tracer High resolution Atmospheric Model). This model simulates the processes 

within the eruption column, and the dispersal of the 

ash cloud on spatial scales of some hundreds of kilometers during some hours. We show the development 

of the ash cloud and of hydrometeors during a plinian 

eruption simulated with the ATHAM model. 

ATHAM can be used to improve understanding of 

in-column processes, and of the initial ash distribution. Better initialization of the usual VAAC models 

will lead to more accurate forecasts of ash dispersal. 

1. Introduction

Various numerical models are used by VAAC centers to forecast volcanic ash dispersal for air traffic 

safety (e.g., VAFTAD, NAME, CANERM, 

HYSPLIT, PUFF, etc.). These emphasize the role of 

background atmospheric motions and ignore the role 

of the eruption dynamics itself upon dispersal. The 

initial ash distribution close to the volcano is often 

not well known and has thus to be prescribed in a 

simplified, sometimes unrealistic way. These models 

tend to have a physically unsound source term description. Their forecasts often fail to accurately predict the extent of the volcanic ash cloud, even for 

small explosive eruptions (e.g., Hekla 2000 eruption, 

Iceland [Grindle and Burcham, 2002; Grindle and 

Burcham, 2003]), especially in the first six hours of 

spreading, with source errors propagated for the 12h+ 

forecasts. For full-blown plinian eruptions or any 

moderately explosive eruptions in weak winds, the 

models often fail to predict ash dispersal with satisfactory accuracy, because of imprecise observations 

of the initial plume height. On the other hand, the 

ATHAM model is a numerical eruption column 

model that predicts the rise of volcanic gases, ash and 

hydrometeors from the lithosphere to the height neutral buoyancy column, and the atmospheric dispersal 

of the plume during the eruption and some hours 

afterwards. The model is based on first physical principles and includes eruption dynamics, cloud meteorology and chemical aspects. ATHAM can be run 

quickly on a fast PC, has a flexible modular structure 

ideal for 1) testing against observations and 2) comparisons with simple numerical simulations and laboratory experiments. In the following, we will introduce the ATHAM model, and then show some results 

form numerical simulations. 

2. Dynamics

ATHAM has been designed to simulate the dispersal of a volcanic eruption [Graf et al., 1999; Herzog 

et al., 1998; Herzog et al., 2003; Oberhuber et al., 

1998]. The simulation time is some hours covering 

spatial scales of some hundreds of kilometers. 

ATHAM is a non-steady state, non-hydrostatic 

model. It solves the full set of Navier-Stokes equations for the multiphase system. Sound waves are 

included, because the flow can be supersonic in the 

high-density lower parts of the eruption column. 

Tracers (liquid and solid particles and gases) can 

occur in very high concentrations in the erupted gasparticle mixture. They act on the dynamics of the 

system by altering the mixture's density and heat 

capacity. The description of this system requires a 

large set of dynamic and thermodynamic equations 

for each component and the interactions between 

them. However, the gas-particle mixture can be assumed to be in thermal and dynamical equilibrium1

, 

on the condition that all particles are smaller than 

about a millimeter. Based on these assumptions, the 

 

1

 Thermal equilibrium: All tracers have the same insitu temperature. Dynamical equilibrium: The 

model does not resolve accelerations between tracers and gas. Tracers move with their terminal fall 

velocity, however, the mixture can be accelerated 

as a whole. 
Session 3 – Page 16 

equations have only to be solved for volume mean 

quantities. For each active tracer one additional 

transport equation is needed that takes into account 

the tracer’s fall velocity. Active tracers and dynamical variables are coupled through the bulk density and 

the heat capacity of the mixture. 

To avoid conflicts with the model assumptions 

processes in the high pressure, hot temperature regime within and close to the crater cannot be resolved, and the topography of the volcanic vent has to 

be neglected. The simulations start just after pressure 

adjustment to atmospheric values, hence we do not 

prescribe any overpressure. Typically, decompression 

takes place within a vertical distance of some jet radii 

above the vent. Hence, we can neglect the topography 

of the volcanic crater and simply use a flat surface. 

Due to the low gas content of the erupting gas-particle-mixture, the temperature does not change significantly during decompression [Woods and Bower, 

1995]. In an explosive eruption, the vertical velocity 

after decompression at the base of the eruption column is about twice the speed of sound for a freely 

decompressing jet. If the apex angle of the crater is 

small, the flow behaves like a high-speed supersonic 

flow in a divergent nozzle and the velocity can be 

even higher. 

3. Turbulence

A turbulence closure scheme describes sub-scale 

turbulent processes in the eruption column [Herzog et 

al., 2003]. Turbulent exchange coefficients are predicted for each prognostic quantity. The strong influence of buoyancy forces and vertical transports in the 

eruption column is represented by differentiating 

between horizontal and vertical turbulent exchange. 

Turbulent disequilibria are possible, and anisotropic 

effects are included in the formulation of turbulent 

kinetic energy. High tracer concentrations as well as 

supersonic effects at low Mach numbers are taken 

into account. The turbulent exchange coefficients are 

derived from a set of three coupled differential equations for the horizontal and vertical turbulent energy, 

and the turbulent length scale. 

4. Cloud microphysics

The development of liquid and frozen meteorological clouds and precipitation is simulated. The effect 

of latent heat release on the dynamics is taken into 

account [Graf et al., 1999; Herzog et al., 1998; Textor et al., 2004]. Two types of schemes can be alternatively used in ATHAM. The bulk scheme [Herzog 

et al., 1998] predicts the mass mixing ratio of liquid 

and frozen hydrometeors, and is for suitable for the 

investigation of latent heat effects on the eruption 

column dynamics. The more complex two-mentscheme [Textor et al., 2004] predicts both the mass 

mixing ratio and the number concentration, and offers 

the possibility to simulate interactions between volcanic particles and hydrometeors. This scheme can be 

used to examine the microphysical properties of volcanic eruption clouds under different volcanic and 

environmental conditions. 

5. Ash aggregation

In the current version of ATHAM, volcanic particles are assumed to aggregate as soon as they are 

coated with water or ice, with the hydrometeors acting as adhesive, thus forming larger hydrometeor-ash 

aggregates [Textor et al., 2004]. The aggregation 

coefficients (describing the ratio of successful particle growth resulting from a theoretical particle collision) are approximated with the parameterizations 

commonly used in cloud microphysics. These values 

are modified with a simple function depending on the 

amount of hydrometeor available at the particle. The 

inclusion of this wet or icy aggregation process leads 

to more realistic sedimentation features. 

6. Gas scavenging

The scavenging module calculates the dissolution 

of volcanic gases (SO2, HCl, H2S, and HBr) by liquid 

droplets and their incorporation into ice particles. The 

kinetics of the phase transfer and the subsequent 

dissociation in the liquid phase is considered as a 

function of the drop acidity. In addition, incorporation into ice particles is taken into account. Gaseous 

compounds enter the ice phase via co-condensation of 

water vapor and gases at growing ice. The concentration of volcanic gases in ice is then rather ruled by 

phase transfer kinetics than by the low equilibrium 

solubility. The redistribution of species contained in 

hydrometeors due to microphysical processes is included [Textor et al., 2003a; Textor et al., 2003b]. 

7. Model concept

The solution of the complete Navier-Stokes equation is computed on a Cartesian Arakawa C grid 

[Mesinger and Arakawa, 1976] using a Eulerian 

method. An implicit time stepping scheme is used 

(Cranck-Nicholson, 25% forward, 75% backward). A 

parallel iteration of the dynamic quantities accounts 

for the temporal coupling of the equations with updated density. The conservation of mass and momentum is explicitly guaranteed by applying the flux 
Session 3 – Page 17 

form for the equations of motion and continuity of the 

tracers. The time step is automatically adapted to 

satisfy the Courant-Friedrichs-Lewy criterion (with 

CFL<= 0.8) and typically varies between 0.1 and 10 

sec. A grid stretching allows using a higher spatial 

resolution in the model center than at the boundaries. 

The grid distances increase from some hundreds of 

meters to some kilometers. The Neumann boundary 

condition (fixed derivatives, open for sound waves) is 

applied at the lateral boundaries. We use a fixed bottom, including tracer deposition as lower boundary 

condition. Pressure and temperature anomalies are 

damped in the upper model levels. 

The ATHAM model can be run in fast, two-dimensional versions for sensitivity studies. The first version in Cartesian coordinates represents a vertical 

slice of the three-dimensional model. The use of 

second two-dimensional version in cylindrical coordinates allows for a more realistic dilution of the 

eruption column in an atmosphere at rest, but crosswind effects cannot be studied. The most realistic 

three-dimensional version has been parallelized for 

efficient use on multi-processor computers [Herzog et 

al., 2000]. 

The ATHAM model is written in a modular structure. It is easy to add additional modules of different 

levels of complexity for specific investigations. 

8. Simulations with the ATHAM model

For the simulation we present here, the ATHAM 

model was initialized with horizontally homogeneous 

profiles of temperature, relative humidity and wind 

representative for a tropical atmosphere, as shown in 

Figure 1. 

 Figure 1: Atmospheric background conditions 

taken from [McClatchey et al., 1972]. 

A plinian eruption of 60 min was simulated 

[Herzog et al., 2003]. The model domain was 

250x200x50 km3, with 127x107x127 grid points. 

Typical plinian conditions prescribed at the eruption 

column base are given below. 

• Mountain height: 2500m, 

• Width of eruption column base: 300m, 

• Temperature: 1073 K, 

• Gas fraction: 6 % by mass, 

• Water vapor fraction of tot. gas: 50% by mass, 

• Bulk density of the gas particle mixture: 3.1 kg/m3, 

• Vertical velocity at eruption column base: 250 m/s, 

• Mass eruption rate: ~5.55 107 kg/s, 

• Particle density: 2000 kg/m3, 

• Three particle classes, 1/3 by mass each, 

• Particle diameter: 10, 200, and 4000 μm. 

Figure 2 shows results from a three dimensional 

simulation (see also [Herzog et al., 2003]) at three 

different times for volcanic ash and for hydrometeors. 

The ash plume is observed from 10-km altitude, that 

of the hydrometeors from somewhat lower. The 

background wind blows from the left side along the 

lines shown on the ground. The eruption column 

penetrates the tropopause at about 17 km after about 

5 min of eruption. The average vertical velocity in the 

central rising zone is larger than 100 m/s. An orographic cloud, which is partly entrained into the 

plume, can be seen on the right of the eruption column between 5 and 10 km in figure 2b. An ice cloud 

forms in the umbrella region (figures 2b, 2d, and 2f). 

After 30 min of eruption, the three particle size 

classes occur at different heights, the umbrella region 

consists mainly of fine ash particles (figure 2c). Larger particles leave the umbrella region more quickly 

due to sedimentation, or do not even reach the height 

of neutral buoyancy. At 70 min of simulation, this 

separation of large particles from the fine ash and 

gases is even more evident (figure 2e). A large ice 

cloud has developed in the stratosphere. Most of the 

hydrometeors in the eruption column are in the frozen 

state (figure 2f). 

9. Conclusions

In this paper, we have presented the concept of 

ATHAM model and the modules available for cloud 

microphysics, ash aggregation and scavenging of 

volcanic gases. In addition, codes for gas phase 

chemistry and for radiative transfer calculations exist 

[Trentmann et al., 2003a; Trentmann et al., 2003b]. 

We have shown results from a three-dimensional 

simulation of a plinian eruption in a tropical environment. These three-dimensional simulations remain 

to be carefully tested against volcanological observations. We plan to simulate a well-observed eruption 

and the first hours of ash dispersal under realistic 

ambient conditions. An earlier evaluation of results 

from the simpler two-dimensional, axis-symmetric 
Session 3 – Page 18 

version confirmed that the results are relatively robust, and three-dimensional fire-simulations have 

been successfully tested against data [Trentmann et 

al., 2002]. 

The ATHAM model has been used for the examination of specific processes and of the parameters 

controlling them within the rising eruption column, 

and during plume dispersal in the atmosphere. Applications included investigations on the influence of the 

ambient conditions on the plume development [Graf 

et al., 1999], on cloud microphysics [Herzog et al., 

1998], gas scavenging [Textor et al., 2003a; Textor et 

al., 2003b] and on ash aggregation [Textor et al., 

2004]. 

Results from sensitivity studies using ATHAM 

provide insights into cloud and aggregation processes, and of ash removal within the eruption column 

(see extended abstract of A. Tupper et al. in this volume). These help to improve the source term matrix 

of the VAAC ash forecasting models and thus to 

more accurately forecast ash for air traffic safety. 

10. References

Graf, H.-F., M. Herzog, J.M. Oberhuber, and C. Textor, The effect of environmental conditions 

on volcanic plume rise, JGR, 104, 24309--

24320, 1999. 

Grindle, T., and F.W.J. Burcham, Even Minor Volcanic Ash Encounters Can Cause Major 

Damage to Aircraft, ICAO journal, 57 (2), 

12-14, 2002. 

Grindle, T., and F.W.J. Burcham, Engine Damage to 

a NASA DC8-72 Airplane From a HighAltitude Encounter With a Diffuse Volcanic 

Ash Cloud, NASA/TM, 2003-212030, 27, 

2003. 

Herzog, M., H.-F. Graf, C. Textor, and J.M. Oberhuber, The Effect of Phase Changes of Water on the Development of Volcanic Plumes, 

JVGR, 87, 55--74, 1998. 

Herzog, M., J.M. Oberhuber, and H.F. Graf, A prognostic turbulence scheme for the nonhydrostatic plume model, JAS, 60, 2783--

2796, 2003. 

Herzog, M., C. Textor, and M. Antonelli, Modelling 

Volcanic Eruption Plumes, HPC News, 13, 

2000. 

McClatchey, R.A., R.W. Fenn, J.E.A. Selby, F.E. 

Volz, and J.S. Garing, Optical properties of 

the atmosphere, 3rd ed., 1972. 

Mesinger, F., and A. Arakawa, Numerical methods 

used in atmospheric models, GARP, 17, 

1976. 

Oberhuber, J.M., M. Herzog, H.-F. Graf, and K. 

Schwanke, Volcanic Plume Simulation on 

Large Scales, J. Volcanol. Geotherm. Res., 

87, 29--53, 1998. 

Textor, C., H.-F. Graf, M. Herzog, and J.M. Oberhuber, Injection of Gases into the Stratosphere by Explosive Volcanic Eruptions, 

JGR, 108 (D19), 10.1029/2002JD002987, 

2003a. 

Textor, C., H.-F. Graf, M. Herzog, J.M. Oberhuber, 

W.I. Rose, and G.G.J. Ernst, Volcanic Particle Aggregation in Explosive Eruption Columns Part I: Hydrometeor-Ash Particle 

Growth in Volcanic Eruption Column Part 

II: Numerical Experiments, submitted to 

Journal of Volcanological and Geothermal 

Research, 2004. 

Textor, C., P.M. Sachs, H.-F.Graf, and T.H. Hansteen, The 12,900 yr BP Laacher See eruption: estimation of volatile yields and simulation of their fate in the plume, in Volcanic 

Degassing, edited by C. Oppenheimer, D. 

Pyle, and J. Barclay, Geological Society, 

London, Special Publications, 2003b. 

Trentmann, J., M.O. Andreae, and H.-F. Graf, 

Chemical processes in a young biomassburning plume, JGR, 108 (D22), 

10.1029/2003JD003732, 2003a. 

Trentmann, J., M.O. Andreae, H.-F. Graf, P.V. 

Hobbs, R.D. Ottmar, and T. Trautmann, 

Simulation of a biomass-burning plume: 

Comparison of model results with observations, in JGR, pp. 10.1029/2001JD000410, 

2002. 

Trentmann, J., B. Früh, O. Boucher, T. Trautmann, 

and M.O. Andreae, Three-dimensional solar 

radiation effects on the actinic flux field in a 

biomass burning plume, Journal of Geophysical Research, 108, 4558, 2003b. 

Woods, A.W., and S. Bower, The decompression of 

volcanic jets in craters, EPL, 131, 189--205, 

1995. 
Session 3 – Page 19 

 

 

Figure 2: Simulation of a volcanic eruption with the three dimensional version of ATHAM LIT. The plots 

show the eruption columns of total ash (size classes: light gray: 10, gray: 200, dark gray: 4000, all in [μm] diameter) on the left hand side (figures 2a, 2c, 2e), and of finest ash and hydrometeors (light gray: 10 μm ash, 

gray: ice, dark gray: liquid water) on the right hand side (figures 2b, 2d, 2f). Three time levels are given (top: 5 

min (figures 2a and 2b), middle: 30 min (figures 2b and 2d), and bottom: 70 min (figures 2e and 2f)). Only a 

fraction of the model domain is depicted; the pale lines at the ground and in the background indicate distances of 

50 km in the horizontal and 25 km in the vertical direction. Visualizations by Michael Boettinger, Deutsches 

Klimarechenzentrum, Hamburg, Germany. 

e f 

a b

c d
Session 3 – Page 20 
3.5 

Session 3 – Page 21 

VOLCANIC ASH AND AEROSOL DETECTION VERSUS DUST DETECTION USING 

GOES AND MODIS IMAGERY 

Bernadette Connell 

Cooperative Institute for Research in the Atmosphere, Colorado State University 

Fort Collins, Colorado, USA 

connell@cira.colostate.edu 

Abstract 

Case examples of the various volcanic ash/aerosol 

and dust aerosol detection techniques utilizing 

infrared wavelengths in the 8-12 μm region are 

presented for the moderate resolution imaging 

spectroradiometer (MODIS) imagery and 

compared with available products from the 

geostationary operational environmental satellite 

(GOES) imagery. Information gained by using the 

short wavelength region (3-4 μm) will also be 

presented. A question that is posed, and partially 

answered is: How is ash, sand or aerosol detected 

with the various channel combinations? 

Introduction 

Volcanic eruptions are extremely variable in 

intensity and composition, they are difficult to 

predict, and they are hazardous. Because of this 

they are often difficult to measure directly and it is 

difficult to track their emissions. Examples are 

limited. Dust and ash tend to be comprised of 

silicates and it is expected that remote sensing 

techniques for detection to be similar. Volcanic 

eruptions are often associated with sulfur based 

aerosols while blowing dust is not. 

Within this paper, easy to implement techniques 

are utilized for detecting volcanic ash and aerosol 

and dust using GOES and MODIS imagery. The 

easy to implement techniques use channel 

differencing of brightness temperature or a 

“normalized” radiance difference product. A 

volcanic ash and a dust example highlight a few of 

the many subtle aspects of detecting ash and dust. 

Because of the variability of the eruption event 

and variability of the weather, no one detection 

technique will work 100% of the time. The 

brightness temperature (BT) difference: 11.0 - 

12.0 μm works the best in distinguishing ash from 

meteorological clouds under ideal conditions. 

This technique will be used to compare against 

techniques from the other channels in the 

shortwave and longwave infrared region. 

Techniques 

Prata (1989a, 1989b) used the brightness 

temperature (BT) difference between the bands 

centered near 11.0 and 12.0 μm to detect ash while 

Shenk and Curran (1974) used this difference to 

detect dust storms. The BT11.0 – BT12.0 is 

generally negative for ash and dust and positive 

for ice and water clouds. 

The use of the 3.9 μm channel for detection of ash 

has been demonstrated by Ellrod et al. (2003) and 

has been shown by Ackerman (1989) for the 

detection of dust. The 3.9 μm channel senses solar 

radiation as well as emitted radiation; hence the 

imagery is interpreted differently during the day 

than at night. For the daytime scenes, scattering 

by particles of shortwave radiation enhances the 

reflectance. For water particles, the reflectance is 

inversely proportional to the drop size. Small 

water droplets are strongly reflective, larger ice 

particles are less reflective. Volcanic ash and dust 

samples show higher reflectance in the 3.9 μm 

region than in the 10.7 or 12.0 μm regions 

(Schneider and Rose, 1994; Salisbury and Walter, 

1989). The reflectance is estimated by: R3.9-

R3.9(BT10.7). The emitted radiance component at 

3.9 μm is estimated using the planck function with 

the measured BT10.7. This is then subtracted off 

the measured radiance at 3.9 μm. 

At night, the detection of an optically thick cloud 

with the 3.9 μm channel is difficult, particularly 

for temperatures colder than -40C, where 

instrument noise becomes large and overwhelms 

the signal. For optically thin clouds, transmission 

plays and important role and the BT3.9 – BT10.7 

is positive for ash cloud (Ellrod et al., 2003). The 
Session 3 – Page 22 

BT3.9-BT10.7 at night is generally positive for ice 

cloud and negative for water cloud. In summary 

for the 3.9-10.7 products, during the day ash and 

dust have a signature similar to that observed for 

water cloud. At night, ash and dust have a 

signature similar to that observed for non-opaque 

ice cloud. 

Baran et al. (1993) and Ackerman and Strabala 

(1994) looked into the use of the 8.3 μm channel 

on the high resolution infrared sounder (HIRS) 

system for the detection of H2SO4 aerosol from the 

Pinatubo eruption. Over oceans there is a small 

negative BT8.3 – BT12.0 background signature 

due to moisture. The BT8.3 – BT12.0 becomes 

more negative for H2SO4 aerosol, and also 

becomes more negative for an increase in 

atmospheric water vapor. The BT8.3-12.0 is 

positive for ice. 

For dust, Ackerman (1997) found that increasing 

the optical depth increases BT8-BT11 over clear 

sky conditions. A thick optical depth results in 

positive BT8-BT11. Wald et al. (1998) simulated 

the MODIS capabilities of the detection of mineral 

dust over desert using the 8.0 - 12.0 μm region. 

Using various particle sizes of quartz and varying 

the optical depth, they found that the BT12.0 – BT 

8.0 was the smallest (ie. negative) (positive for 

BT8.0 – BT 12.0) for 2 μm particles and small 

optical depth and was positive for large optical 

depth, taking on the signature of the quartz sand 

background. All authors mentioned in this 

paragraph discuss the difficulties encounter over 

land surfaces where diurnal temperature variations 

and variable surface emissivities affect BT8. 

Examples 

The eruption of the Popocatepetl volcano in 

Mexico on 22-23 January 2001 was chosen 

because the eruption started later in the day on the 

22nd, providing a brief example of the reflectance 

seen in the 3.9 μm channel, with drifting ash 

continuing through the night when the first 

MODIS imagery is available. According to the 

volcanic ash advisory issued by the Washington 

Volcanic Ash Advisory Center, the explosive 

event started at approximately 22:15 UTC on 22 

January 2001. Figure 1 shows the erupting plume 

at 22:45 UTC. The outline of the plume is shown 

on the visible imagery in Figure 1a. The stratus 

cloud to the east is also labeled. In the reflectance 

product (figure 1b), enhanced reflectance is noted 

for the eruption plume and appears brighter than 

Figure 1. GOES imagery showing the erupting 

plume from the Popocatepetl volcano in Mexico 

on 22 January 2001 at 22:45 UTC. a) visible 

imagery, b) reflectance product using the 3.9 and 

10.7 μm imagery, and c) BT10.7-BT12.0 
Session 3 – Page 23 

the stratus cloud. The cloud shape resembles a 

convective cloud and would normally appear 

darker because of the presence of less reflective 

ice particles. The BT10.7-BT12.0 product (figure 

1c) shows negative values for the plume with the 

most negative value (-7.7) along the southeastern 

edge where the plume is thinner. 

A night scene of the eruption plume is displayed in 

figure 2. The GOES imagery (figure 2 a, b) are 

from 04:45 UTC on 23 January 2001, and the 

MODIS Terra imagery (figure 2 c, d) are from 

04:50 UTC. The pattern of the GOES and MODIS 

BT11-BT12 shown in figure 2a and 2c are very 

similar. The GOES product produced more 

negative differences in background regions as well 

as in various parts of the plume. The differences 

were generally relatively small (0.5C) as in the 

circled regions x and y, but got as large as 2.0C in 

circled region Z (-5.5C for GOES and -3.3C for 

MODIS. At this point it is unclear as to whether 

the differences are a result of the sampling 

differences associated with different spectral 

coverage, spatial coverage, or viewing angle. The 

GOES 10.7 channel has a bandwidth of 10.2-11.2 

μm, while the MODIS 11.0 μm channel has a 

bandwidth of 10.78-11.28 μm. The GOES 12.0 

μm channel has a bandwidth of 11.5-12.5 μm, 

while the MODIS 12.0 μm channel has a 

bandwidth of 11.77-12.27 μm. 

The GOES BT10.7-BT3.9 shown in figure 2b 

shows the plume quite well. In this case it is 

because of the contrast of the plume with the 

brighter lower level stratus and ground surface. 

Tracking of the plume with the GOES imagery 

Figure 2. Satellite imagery products showing the erupting plume from the Popocatepetl volcano in 

Mexico on 23 January 2001, GOES at 04:45 UTC and MODIS Terra at 04:50 UTC. a) GOES BT10.7-

BT12.0, b) GOES BT10.7-BT3.9, the dashed line indicates the plume outline c) MODIS BT11.0-BT12.0, 

and d) MODIS BT8.5-BT12.0. 
Session 3 – Page 24 

through time helped significantly in discerning 

various portions of the plume that are outlined in 

figure 2b. The BT8.5-BT12.0 image provides 

another view of the plume and its characteristics. 

It has many regions of negative difference similar 

to BT11.0-12.0 (figure 2c) and one region in 

particular indicated by circle z has much stronger 

negative differences (-14.0C). Regions circled as 

x and y show slightly positive differences. The 

modeling efforts referenced in the previous section 

suggest that the regions of positive differences in 

circles x and y contain smaller particles and small 

optical depth. The more negative differences 

observed in circle z reflect the presence of SO2 and 

sulfates and a larger optical depth. 

An example of blowing dust during the day is 

shown in figure 3 for 18 April 2004 at 19:30 UTC. 

The extent of the plume is highlighted with dashed 

lines in the MODIS BT11.0-BT12.0 (figure 3c) 

image. Both the MODIS and the GOES difference 

product for BT11-BT12 (figure 3c and 3a 

respectively) show similar values (most negative 

value = -2.5, average = -2.0 and -1.5 respectively) 

for the thicker part of the plume, represented by 

the circle labeled y. They also show similar values 

(1.0 and 0.0 = the most positive values 

respectively, average=-0.5) for the thinner portion 

of the plume labeled as circle x. The extent of the 

dust plume for these difference products agrees 

with that shown by the GOES reflectance product 

in figure 3b. In this product, the dust as well as 

low level water clouds appear more reflective. In 

contrast, the MODIS BT8.5-BT12.0 product 

shown in figure 3d represents the plume with 

values -1.0 – 0.0 in what appears to be the densest 

Figure 3. Satellite imagery products showing the dust plume extending from Colorado into 

Kansas and Nebraska on 18 April 2004, GOES and MODIS Aqua at 19:30 UTC. a) GOES 

BT10.7-BT12.0, b) GOES reflectivity product using the 3.9 and 10.7 channels c) MODIS 

BT11.0-BT12.0, the dashed line indicates the plume outline, and d) MODIS BT8.5-BT12.0. 
Session 3 – Page 25 

region labeled as circle y. In the circled region 

labeled as x, the most negative value is -7.0 with 

an average value of -5.0. These observations are 

opposite what is expected from the modeling 

results referenced in the previous section. Further 

information is needed on the effect of surface 

emissivities, particle size, and opacity of the 

plume. 

Summary 

Blowing dust has characteristics similar to 

volcanic ash and techniques used for its detection 

can be extended to volcanic ash detection. The 

BT11-BT12 technique is the most widely used 

technique in the detection of volcanic ash. It has 

also been used with success in detection of 

blowing dust. There are many instances when the 

3.9 μm products enhance the ash plume and 

blowing dust plumes. Even though the signature 

does not uniquely distinguish it from 

meteorological cloud, it can be used in conjunction 

with the other products to better delineate the 

extent of coverage. 

The 8.5 μm channel is currently available on the 

MODIS satellites. It has the capability to detect 

SO2 and sulfates as well as ash and dust. In 

general, the presence of SO2 and sulfates will 

make the BT8.5-BT12.0 signal negative. The 

presence of small (2 μm) quartz dust (or ash) 

particles and a low optical depth will result in a 

positive BT8.5-BT12.0 signal. High optical depth 

results in a negative BT8.5-BT12.0, similar to 

viewing a quartz ground signal. The night 

volcanic ash case viewed here showed features 

that seemed to be consistent with both the 

presence of ash and aerosol. The day dust case 

had negative and positive regions that were not 

consistent with what was expected. 

Since the detection of SO2 and sulfates is desirable 

along with the detection of ash, further research is 

needed to determine regional sensitivities to the 

background surface emissivity and particle size as 

well as optical depth in the 8.5 μm region. This 

will help to develop a more robust and 

comprehensible product to be used in monitoring 

volcanic emissions. 

Acknowledgements 

This work is supported by NOAA Grant 

NA17RJ1228. 

The MODIS data used in this study were acquired 

as part of the NASA's Earth Science Enterprise 

and archived and distributed by the Goddard Earth 

Sciences (GES) Data and Information Services 

Center (DISC) Distributed Active Archive Center 

(DAAC). 

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Geophys. Res., 103 (D24): 32,307-32,313. 
Ice in Volcanic Clouds: When and Where?

William I Rose, Gregg JS Bluth and I Matthew Watson

Michigan Technological University, Houghton, MI 49931 USA

Volcanic clouds are suspensions of particles,

analogous to meteorological clouds. In

volcanic clouds the particles include volcanic

ash, hydrometeors (raindrops, snow, hail,

graupel, sleet, etc), sulfate aerosols and

particles that are mixtures or

conglomerations of all the other particle

types present. Ash fall is analogous to rain,

hail or snow, and consists of large ash

particles in descent. Ash fall occurs most

markedly from the high energy first stage of

volcanic clouds, with or without

precipitation, near the vent and soon (<1hr)

after eruption (Rose et al, 2000). Volcanic

clouds exhibit a second stage of evolution,

lasting a day or so, where rapid physical and

chemical changes occur and when ash fall

This paper explores published data from

remote sensing and other sources concerning

the existence of ice particles in volcanic

clouds, to attempt to reveal patterns in its

variability. We use data from a variety of

satellite sensors and using several different

algorithms for retrieval of information about

ice, ash, sulfate and SO2 (Table 1), applied to

eruptions of the last few decades.

If one type of particle is dominant in the

volcanic cloud, it is challenging to use these

remote sensing algorithms to quantify the

subordinate particles. We discuss in this

paper cases when ice is the dominant particle

type, when ash is dominant and when ash and

ice are similar in mass proportions.

Table 1 Algorithms used for volcanic cloud sensing retrievals, see also Watson et al (2004)

Name Sensor (s) Objective Reference(s)

2 band BTD GOES,

AVHRR,

MODIS

Mass of fine

( > 15 μm radius) ash,

Particle size

Wen & Rose, 1994;

Yu et al, 2002 (atmospheric corrections

Rose et al, 1995 (ice retrievals)

8.6 μm SO2 MODIS,

ASTER

SO2 mass Realmuto et al, 1997

7.3 μm SO2 MODIS,

HIRS/2

SO2 mass Prata et al, 2003 (HIRS/2)

Prata et al, in prep (MODIS)

UV SO2 TOMS SO2 mass Krueger et al, 1995

Multiband

IR

MODIS Fine ash, ice, sulfate

masses

Yu & Rose, 2000

GOES = Geostationary Operational Environmental Satellite; AVHRR= Advanced Very High Resolution

Radiometer; MODIS= Moderate Resolution Imaging Spectroradiometer; ASTER= Advanced Spaceborne Thermal

Emission and Reflection Radiometer; TOMS= Total Ozone Mapping Spectrometer

occur and when ash fall (and precipitation) is

muted and controlled by aggregation of ash

particles too small to fall by themselves. A

third stage of volcanic clouds lasts several

more days and consists of drifting over

hundreds or thousands of km and very slow

fallout (Rose et al, 2003).

Ice Dominant Volcanic Clouds

Rabaul, Papua New Guinea 1994

The Rabaul eruption was the event which

made us realize that ice could be the

dominant particle in volcanic clouds. The

eruption came from dual vents on opposite

sides of a caldera breached by the ocean

and resulted in a 20 km high eruption cloud
which was detected by satellite sensors such as

the polar orbiting AVHRR. Numerous

conventional photographs from the Space

Shuttle (http://www.geo.mtu.edu/volcanoes

/rabaul/shuttle/) show that this cloud had a

bright white color like a meteorological cloud.

Infrared remote sensing showed that the cloud

contained >2 MT of ice. Salty rain falls

occurred in a wide arc N and NW of the

volcano and there were wet ash and mud falls

which contained sea salt, although ash could

not be detected by satellite remote sensors.

The Vulcan vent (the main source of the

Rabaul eruptions) was itself breached, and so

the ocean flowed directly into the active vent

during eruption. Thus the ice in the great cloud

may have largely been the result of evaporation

of the ocean (Rose et al, 1995). Remote sensing

also revealed that the Rabaul volcanic cloud

contained relatively low levels of SO2 (80 + 50

kT), which suggested that ice sequestered much

of the volcanic gas and removed it from the

volcanic cloud by precipitation in the early

stage of the volcanic cloud. Overall this

example showed that ice could reduce the

residence time of both ash and SO2 in the

volcanic cloud, an idea suggested by Pinto et al

(1989).

Hekla, Iceland 2000

The Hekla eruption was a small (ash volume

~ 0.01 km3; total magma volume ~0.17 km3

and mass about 3x105 MT) fissure eruption

of lava preceded by a brief (1-2 hr) explosive

phase that produced an eruption cloud which

suddenly reached 10-12 km. Meteorological

radar was a useful monitoring tool to

document the explosive eruption and the

growth of ice in the volcanic cloud (Lacasse

et al, 2004). The volcanic cloud was mapped

by a variety of satellite sensors as it drifted N

of Hekla toward Svalbard for 2 days (Rose et

al, 2003). It was also traversed by a research

aircraft with in situ atmospheric sensors. In

spite of the small scale of the eruption, the

Hekla volcanic cloud contained >1 MT of

ice and 160-240 kT of SO2. Ash was a minor

component and was detected by remote

sensors only in the first hour of the eruption

(~100 kT or .1 Tg). The ice mass in the

volcanic cloud declined by an order of

magnitude before the aircraft encounter 35

hours after eruption (figure 1).

Total Mass

0

200000

400000

600000

800000

1000000

1200000

0 5 10 15 20 25 30

Time after eruption (hours)

Total mass (metric tons)

ice_AVHRR

ice_MODIS

ash_AVHRR

Figure 1: Time based determinations of particle masses determined using the multispectral IR

retrieval of Yu & Rose (2000) for the Hekla Volcanic Cloud (Rose et al, 2003).
Examples where ice is clearly subordinate

Spurr, Alaska 1992

Crater Peak, Mount Spurr Alaska had 3 similar

VEI=3 eruptions in 1992. Each resulted in a

volcanic cloud which reached the lower

stratosphere (~14 km asl) and had eruptive

volumes of about 0.01-0.02 km3

 (Rose et al,

2001). All three events were studied with

AVHRR sensors which enabled us to estimate

masses of several hundreds of kilotonnes of fine

(<15 μm radius) ash particles. These particle

masses declined markedly during the first 18-24

hours due to aggregate formation and fallout. No

ice could be detected with remote sensing in any

of these clouds. We used atmospheric profile

information and a numerical model called

ATHAM which includes microphysical processes

(Textor et al, 2003) to determine the likely

amounts of ice in the Spurr volcanic clouds and

found that the model results showed that ice

concentrations in the Spurr Clouds were of the

order of a few % of the fine ash concentrations.

One factor that limits the ice is the low

concentrations of H2O in tropospheric air at high

latitudes, which limits the entrained water vapor

in the column. The low proportions of ice in

Spurr volcanic clouds may limit the fallout of icy

aggregates which accelerate ash removal in other

clouds. We also note that the Spurr clouds did

not show separation of ash and SO2 (See

discussion in Rose et al, 2001).

Cleveland, Alaska 2001

Cleveland is a stratovolcano 1730 m high located

1500 km SW of Anchorage in the east central

Aleutians. With 11 eruptions since 1893 and ash

eruptions in 1987 and 1994, it is relatively active.

As it is unmonitored seismically and remote,

satellite observations of thermal anomalies and

eruption clouds play a vital role in monitoring

(Dean et al, 2004). In 2001, Cleveland erupted on

February 19, March 11 and March 19. On

February 19, the largest of the three events

produced ash eruptions that lasted 8-9 hours and

which were observed by satellite sensors (GOES,

AVHRR and MODIS) for 48 hours. The fine

(<15 μm radius) ash masses in this volcanic

cloud was found to be ~30 kT and the SO2 mass

was ~10 kT. There was a sight separation of ash

and SO2, suggesting that the SO2 was emitted

earlier and higher. No ice signal could be

detected. The most important new observation

about the Cleveland eruption was the enhanced

sensitivity of the infrared detection from the

large satellite zenith angles (Gu et al, in prep).

Other ice subordinate examples.

We have observed more examples of ash

dominant volcanic clouds, such as Augustine,

1986 (Holasek & Rose, 1991) and

Kluychevskoi, 1994 (Rose et al, 1995). We

note that these examples are all at latitudes

>40, which suggests that tropospheric water

vapor, which is much higher at tropical

latitudes, influences volcanic cloud ice through

the entrainment process (Glaze et al, 19xx).

Subequal Proportions of ice and ash in

volcanic clouds

Pinatubo, Philippines 1991

The largest eruption of the past 25 years,

Pinatubo produced truly global scale

atmospheric changes from its climactic

eruption on 15 June 1991 (McCormick et al,

199x). About 80 MT of ice, about 50 MT of

fine ash (<15 μm radius), and 18-19 MT of SO2

were found in Pinatubo’s huge volcanic cloud

by Guo et al (2004a, 2004b). The coexistance

of ice and fine ash makes retrieval using the

two band BTD method of Wen & Rose

difficult or impossible (Figure 2). This

observation highlights an important issue for

volcanic cloud detection, and provides a need

for further development of multispectral

infrared retrieval algorithms such as Yu &

Rose (2000). The effects of ice in the Pinatubo

cloud were marked: 1. SO2 was apparently

significant sequestered by ice (Figure 3) during

the first day of atmospheric residence (Guo et

al, 2004a) and 2. The ice and the ash fell out of

the cloud quickly (about 90% removed in 3

days) and at very similar rates, suggesting that

they fell out as ice/ash aggregates (Guo et al,

2004b).

Soufrière Hills, Montserrat, 26 December

1997

On 26 December 1997, the volcanic dome at

Soufrière Hills, Montserrat collapsed

catastrophically, producing a debris avalanche,
Figure 2: Brightness temperature difference (BTD) of band 4 (=11 μm) and Band 5 (=12

μm) data from AVHRR plotted against band 4 brightness temperature for two eruption

clouds: a: Rabaul, 19, Sept, 1994, which was interpreted as ice dominant and b:

Kluchevskoi, 1 October 1994, which was interpreted and ash dominant (Rose et al, 1995).

Figure 3: BTD plot, as in figure 2, but for the volcanic cloud of Pinatubo, 15

June 1991. This volcanic cloud is extremely variable and plots mainly in region

labeled “mixtures”, and only partly in the fields labeled “ash region” and “ice

region”. Compare with figure 2.
a pyroclastic density current and an ash cloud

which rose to 15 km (Sparks et al, 2003).

Because the density current carried hot

andesite directly to the sea, the evaporation

of the ocean led to the formation of a

volcanogenic meteorological cloud, which

also rose to stratospheric levels. The mapping

of two stratospheric clouds and their particle

masses (~45 kT fine ash (<15 μm radius) in

the volcanic cloud; ~150 kT ice in the

volcanogenic meteorological cloud) was

demonstrated by Mayberry et al (2003). The

two clouds overlapped in their two

dimensional extent as they drifted SE for

more than 6 hours.

El Chichón, Mexico 1982

The El Chichón eruption consisted of 3 large

phases (the first and smallest on March 29

and the other two on April 4, 1982). The

April 4 events produced a volcanic cloud

which dramatically separated into a higher

(22-26 km high) westward-drifting SO2 rich

volcanic cloud and a lower (19-21 km high)

which contained most of the fine ash erupted

(Schneider et al, 1999). The April 4 events

produced ~ 7 MT of SO2 and about 7 MT of

fine ash (<15 μm radius) and the mass map

of the cloud is obscured along its eastern

edge (figure 4). By analogy with the

Pinatubo example, we suggest that this is due

to ice, which is present in proportions

subequal to fine ash. The existence of ice

may also explain the very rapid ash fallout

observed by the satellite sensors, where

>90% was lost in 3 days.

Conclusions

Ice is present in all cold volcanic clouds and

this has important implications for hazards.

For detection using infrared remote sensing,

ice presence in the volcanic cloud interferes

with volcanic ash, which means that the

simplest detection schemes (2 band

brightness temperature differencing) may be

less sensitive or even ineffective.

Ice may be dominant, subordinate or

subequal to ash in terms of mass in volcanic

clouds and we have found good examples of

each of these cases in the last 25 years. High

latitude volcanoes are likely to be ice poor,

perhaps because entrainment of tropospheric

H2O by the eruption column is limited by the

drier high latitude troposphere.

Besides entrained tropospheric water vapor,

sources of H2O for volcanic cloud ice

includes, magma, various hydrospheric

reservoirs (ocean, crater lakes, glaciers,

groundwater) and hydrothermal systems.

Ice in volcanic clouds enhances ash fallout

by forming composite aggregates.

Ice forms immediately after eruption, and

then decreases markedly by an order of

magnitude in only a few days, apparently

sublimating as well as precipitating from the

drifting volcanic cloud.

Ice sequesters SO2, and can remove it by

precipitation or release it during sublimation,

so that SO2 masses in volcanic clouds have

been observed to increase for 1-2 days after

eruption.

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3.7 

Session 3 – Page 35 

FIRST MEASUREMENTS OF VOLCANIC SULPHUR DIOXIDE FROM THE GOES 

SOUNDER: IMPLICATIONS FOR IMPROVED AVIATION SAFETY 

Fred Prata1

, 

Tony Schreiner2

, Tim Schmit2, 

Gary Ellrod3

, 1

CSIRO Atmospheric Research, Aspendale, Victoria, Australia 2

NOAA/NESDIS, Office of Research and Applications, Madison, WI, U.S.A.CIMSS, University of WisconsinMadison, Madison, WI 53706, U.S.A. 3

NOAA/NESDIS, Office of Research and Applications, Camp Springs, Maryland, U.S.A. 

Abstract 

 The GOES sounder is a multi channel imaging filter radiometer operating in the infrared to 15 μm, providing 

up to hourly data at 10x10 km2

 spatial resolution and covering large parts of the globe. The principal aim of the 

sounder is to provide vertical profiles of atmospheric temperature and moisture for global weather applications. 

Analysis of data acquired during the July, 2003 eruptions of Soufriere Hills, Montserrat, suggests that some of the 

channels can be used to detect upper tropospheric SO2. We provide qualitative and quantitative assessments of 

GOES’ ability to detect SO2, illustrated with examples and suggest its advantages and limitations compared to other 

satellite measures of SO2. Currently three GOES sounders are operational at longitudes: 134.85o

E, 99.66oW, and 

74.78o

W. The temporal frequency and constant viewing angles of the GOES platform make them an ideal system 

for providing timely aircraft warnings of the presence of upper tropospheric/lower stratospheric SO2, and 

consequently are useful for monitoring hazardous volcanic clouds. 

Introduction 

Satellite measurements of volcanic gases and particles 

(volcanic ash) are increasingly used by the aviation 

community to alert them of the possibility of a 

hazardous encounter. It is well recognized that an 

encounter with a volcanic ash cloud is likely to cause 

severe damage to jet engines with the likelihood of loss 

of power and ultimately loss of the aircraft and lives. A 

tragedy of this kind has not occurred, yet. However, jet 

aircraft continue to intercept ash clouds at alarming 

frequency. Many airline operators are cognisant of the 

dangers and take very conservative measures to avoid 

volcanic clouds, when their presence is known. This 

sensible action comes at the cost of increased mileage 

through re-routing and consequently airlines incur an 

economic penalty. 

An encounter with a volcanic cloud is often first 

noticed by the pilot, cabin crew and passengers through 

the sensing of the presence of sulphur odours. The 

characteristic pungent odour of sulphur dioxide is an 

effective indicator. Occasionally, other signs of an ash 

encounter will be noticed; for example, “St Elmo’s 

Fire”, “smoke” in the cabin or observation of a darker 

than usual cloud. Later inspection of external surfaces 

will confirm whether an encounter has occurred. The 

severity of the encounter may require expensive engine 

checks or repairs to be carried out. In exceptional 

circumstances these checks and repairs may cost many 

millions of dollars. In many cases it is not known how 

severe the encounter has been until the checks have 

been undertaken. If the tell-tail signs of an encounter 

have been reported by the pilot and crew and advisories 

have indicated the possible presence of a volcanic cloud 

within the flight path, then thorough checks on the 

aircraft would seem warranted. However, not all 

encounters with volcanic clouds are necessarily 

encounters with volcanic ash. Recent research suggests 

that volcanic eruptions that produce ash and SO2 may 

deposit these substances at different heights in the 

atmosphere. Vertical wind-shear will then cause 

transport of the ash and SO2 clouds along different 

trajectories. This separation of the ash and gas appears 

to be common (see Bluth et al., 1994 for an example). 

An encounter with an SO2 cloud, as opposed to an ash 

cloud, will not cause engines to stall, will not cause 

abrasion of surfaces, and will not clog up pitot static 

tubes. While still to be avoided, encounters with SO2

clouds are likely to lead to much less airframe damage 

and may call for a quite different overhaul procedure 

and repair. The costs of checks and repairs for an 

encounter with an SO2 cloud are likely to be much less 

than those for an encounter with an ash cloud. These 

factors suggest that airlines need to know whether a 

volcanic cloud is predominantly SO2 or predominantly 

ash. The current state of the science indicates that it is 

possible to detect both SO2 and ash clouds from 

satellite-borne instruments simultaneously and monitor 
Session 3 – Page 36 

their progress through the airways. This paper and a 

complementary paper by Schreiner et al. (2005) report 

a new observation of SO2 clouds detected by the 

operational GOES sounder and suggest that use of the 

GOES sounder data will provide airlines with useful 

additional information on the composition of volcanic 

clouds. 

The GOES Sounder 

The Geostationary Orbiting Environmental Satellites 

(GOES) series provide frequent imagery and soundings 

for large parts of the globe. The current series are 

operationally known as GOES-8 through to GOES-12. 

The platform houses two instruments that view the 

earth – an imager and a sounder. Table 1 lists the band 

numbers and their respective central wavelengths for 

the GOES-12 platform. 

GOES-12 

Imager band 

Central 

wavelength (μm) 

1 0.65 

2 3.9 

3 6.48 

4 10.7 

5 13.3 

GOES-12 

Sounder band 

Central 

wavelength (μm) 

1 14.71 

2 14.37 

3 14.06 

4 13.64 

5 13.37 

6 12.66 

7 12.02 

8 11.03 

9 9.71 

10 7.43 

11 7.02 

12 6.51 

13 4.57 

14 4.52 

15 4.46 

16 4.13 

17 3.98 

18 3.74 

Table 1. Band numbers and central wavelengths for the 

GOES-12 imager and sounder. Note that the GOES 

sounder also has one broadband visible channel, not 

listed above. 

The imager is used widely to provide frequent 

qualitative images for meteorological weather 

forecasting and analyses. The sounder is used for 

quantitative retrieval of atmospheric temperature and 

moisture profiles. This paper reports a new use for 

some of the sounder channels and the following 

discussion is restricted to the sounder. The spatial 

resolution of the sounder is ~10x10 km2

 and the 

temporal frequency is up to once per hour. Although 

the spatial scale is poorer than many of the polar 

orbiting satellites (e.g. AVHRR and MODIS), its 

temporal sampling is better. 

SO2 Retrieval 

Sulphur dioxide has strong absorption bands in the 

infrared near to 4, 7.3 and 8.6 μm. The GOES sounder 

has bands at 3.98 and 7.43 μm (see Table 1). The band 

at 3.98 μm measures both reflected solar radiation and 

thermal emission, in approximately equal amounts 

under standard conditions. The band at 7.43 μm while 

not ideally situated for SO2 detection does not include 

solar reflected radiation and covers the much stronger 

7.3 μm SO2 band. Sounder band 10 is also negligibly 

affected by volcanic ash, which can be detected 

independently by using the 11 and 12 μm bands (7 and 

8) through the ‘reverse’ absorption effect (e.g., Prata, 

1989). 

A difficulty associated with retrieving SO2 from band 

10 arises because this band is responsive to midtropospheric water vapour. Indeed, the band is 

intended for studies of tropospheric water vapour. If 

the SO2 cloud is high and concentrated however, then 

band 10 will respond to absorption due to SO2. 

Typically for optimum detection, the SO2 cloud should 

be situated near 200-300 kPa (5-8 km) and be relatively 

free of in-cloud water vapour. When such conditions 

are met then band 10 should register an anomalously 

low radiance (or brightness temperature). In practice, 

the height of the cloud is unknown and there is always 

likely to be some water vapour (or large amounts) in 

the volcanic cloud. To account for some absorption 

due to water vapour, a temperature difference image 

can be made. The difference removes some of the 

variations in radiance due to the heterogenous radiance 

field impinging onto the lower part of the SO2/H2O 

cloud. The heterogeneity may be due to variations in 

the radiation from the surface or atmospheric layers 

below the cloud, or may be due to horizontal variations 

in lower troposphere water vapour. We used several 

band differences to determine an optimum second band 

that maximised the SO2 response. Ideally, three bands 

should be used:- two centred outside the 7.3 μm 

absorption feature and one band situated on the 

absorption feature. Bands 9, 11 and 10 seem obvious 

choices for the GOES-12 sounder. The approach taken 

for GOES SO2 retrieval follows the method outlined by 

Prata et al. (2004). In this method a synthetic radiance 
Session 3 – Page 37 

(or brightness temperature) is computed by linear 

interpolation of channels either side of band 10. The 

difference between the brightness temperature in band 

10 and the synthetic value calculated for this band is a 

measure of the absorption due to SO2. The reasoning 

behind this follows from the assumption that only SO2

gas is causing the anomalous behaviour of band 10, and 

that water vapour effects have been removed through 

differencing with the synthetic estimate. The reader is 

referred to Prata et a.l (2004) for an in depth discussion 

of the veracity of these assumptions and for further 

information on the retrieval scheme, including the 

effects of water/ice clouds. Figure 1 shows the results 

of applying the retrieval scheme to four image frames 

of GOES-12 data for the July eruption of Soufriere 

Hills volcano on Montserrat.

Figure 1. Sequence of GOES-12 SO2 retrievals for the Soufriere Hills eruption, Montserrat. Each frame is 

separated by 6 hours in time (see the captions for day of year and time in UTC). SO2 units are milli atm-cm. 
Session 3 – Page 38 

The Soufriere Hills eruption is described in detail in the 

BGVN (2003). Analysis of the movement of the ash 

from this eruption suggests that it travelled 

predominantly to the west and west-northwest (Figure 

2). By contrast the (higher) SO2 cloud travelled 

northeast. This separation of the ash and SO2 is a 

common feature of volcanic clouds that reach well into 

the upper troposphere (Bluth et al., 1994) and is a 

consequence of wind shear and the difference in 

densities of gases and particulates. 

Figure 2. Volcanic ash from Soufriere Hills volcano. 

This MODIS image shows that the ash from Soufriere 

Hills moved westwards, whereas the SO2 moved 

towards the northeast. 

Validation 

The Soufriere Hills eruption was monitored by several 

satellite instruments capable of measuring SO2. These 

include, TOMS, MODIS and AIRS. Ground-based SO2

flux measurements were also made during the eruption. 

The TOMS instrument estimated about 80 kT of SO2

and the AIRS instrument retrieved values from 10 kT 

up to 290 kT, compared with the GOES retrievals of 77 

kT up to 186 kT The errors in the SO2 retrievals from 

these instruments are generally of the order 10-30%, 

and differences in timing, spatial coverage and footprint 

size preclude a comprehensive validation. However, 

the GOES retrievals are within the expected range of 

variation and compare quite favourably with AIRS and 

TOMS. We also note that the GOES band 10 is not 

optimum for quantitative SO2 detection–the band centre 

is too far towards the long wavelength side of the SO2

absorption and the band is a little broad. 

For use by the aviation industry, quantitative SO2

estimates may be of much less value than the certainty 

of identification; here the question of GOES sensitivity 

may be more important. Schreiner et al. (2005) show 

that GOES was able to track the SO2 cloud for at least 

two more days at 6 hour time resolution. 

Conclusion and implications for aviation safety 

Work reported by Schreiner et al (2005) and in this 

paper, demonstrate that GOES may be useful in 

detecting volcanic SO2 clouds that persist in the uppertroposphere/lower stratosphere and consequently may 

intersect airways. We have argued that clear 

identification of SO2 from ash in volcanic clouds may 

be of economic benefit to the airline industry. Use of 

the 7.2-7.6 μm region for SO2 detection looks 

promising as the effects of volcanic ash are much less; 

although water vapour absorption limits the detection to 

SO2 residing at altitudes above 10,000 feet or so. It 

seems quite possible that a simple SO2 index could be 

determined from GOES sounder data and transmitted to 

VAACs for dissemination to the airlines. Information 

in such images could be used in conjunction with 

trajectory models and other satellite data that detect 

volcanic ash, to allow airline operators to determine 

safe air routes. Furthermore, information gleaned from 

pilots and crew that believe they have encountered a 

volcanic cloud can be fused with the SO2 and ash 

images to determine appropriate aircraft checks and 

maintenance procedures. An encounter with an SO2

cloud is unlikely to warrant expensive aircraft repair, 

while it is known that an encounter with an ash cloud 

can lead to major engine damage. 

References 

Bluth, G.J.S., Casadevall, T.J., Schnetzler, C.C., 

Doiron, S.D., Walter, L.S., Kruger, A.J., and M. 

Badruddin, Evaluation of sulphur dioxide emissions 

from explosive volcanism: the 1982-1983 eruptions 

of Galunggung, Java, Indonesia, J. Volcanol. 

Geotherm. Res., 63, 243-256, 1994. 

BVGN, Bulletin of the Global Volcanism Network, 

 Vol. 28, No. 7, 5-7, 2003. 

Prata, A. J., Infrared radiative transfer calculations for 

volcanic ash clouds, Geophysical research letters, 

16, 1293-1296, 1989. 

Prata, A. J., Rose, W. I., Self, S., and D. M., O’Brien, 

2003, Global, long-term sulphur dioxide 

measurements from TOVS data: A new tool for 

studying explosive volcanism and climate, 

Volcanism and the Earth’s Atmosphere, Geophys. 

Monograph 139, AGU, 75–92. 

Schreiner, A. J., Schmit, T. J., Ellrod, G., and Prata, A., 

Can upper-level SO2 be monitored using the GOES 

sounder?, Submitted to 85th Annual AMS meeting, 

9-13 January, 2005, San Diego, CA. USA. 
3.8 

Session 3 – Page 39 

GROUND-BASED DETECTION OF VOLCANIC ASH AND SULPHUR DIOXIDE 

Fred Prata and Cirilo Bernardo 

 CSIRO Atmospheric Research, Aspendale, Australia 

Matthew Simmons and Bill Young 

Tenix Investments, Sydney, Australia 

Abstract 

We present the first ground-based thermal infrared image data showing detection and discrimination of volcanic ash 

and sulphur dioxide gas emitted from erupting volcanoes. The images are acquired from a new multichannel 

uncooled thermal imaging camera suitable for deployment within ~10 km of an active volcano. Algorithms for ash 

and SO2 detection are described. Images from the system, named G-bIRD (Ground-based InfraRed Detector) are 

acquired rapidly (within a few seconds), analysed and transmitted via satellite or landline to a computer with access 

to the Internet and utilising a standard web browser. Tests of the system have been undertaken at Etna and 

Stromboli, Italy, at Anatahan, Northern Mariana Islands and at Tavurvur, Rabaul, Papua New Guinea. G-bIRD 

offers a new means for monitoring hazardous volcanic substances from the ground and could provide 

complementary information for providing volcanic ash and SO2 warnings to the aviation industry. 

Introduction 

Volcanic ash is a hazard to jet aircraft, causing engines 

to stall when ingested, scouring windows and the 

leading edges of the wings and causing instrument 

malfunctions (Casadevall, 1994 and references therein). 

Damage to aircraft can be counted in the millions of 

dollars. Most serious aircraft encounters with ash 

clouds have been at cruise altitudes (e.g. Tupper et al., 

2004), but there is also a hazard to aircraft at airports 

affected by volcanic ash (Guffanti et al., 2004 this 

volume). These airports are usually close to an active 

volcano (e.g. Anchorage and Kagoshima) but they can 

also be at some distance from the source of the eruption 

due to atmospheric transport that brings ash into the 

region. This paper addresses the problem of detecting 

volcanic ash in the vicinity of airports and suggests a 

practical design for an infrared device that can monitor 

the sky overhead. The cost of ash hazards to airport 

operations is not known, but must be significant if the 

costs include those due to delays to landings and takeoffs as well as re-routing costs incurred by airline 

operators (Cantor, 1998). Other environmental 

hazards consist of the toxic gases emitted by 

volcanoes. Of particular importance and abundance is 

sulphur dioxide gas. This gas is colourless, but has a 

characteristic pungent odour. Eye irritation and 

inflammation of the respiratory tract occurs at relatively 

low concentrations. Amounts of 6-12 ppm will cause 

immediate irritation of the nose and throat. Long term 

exposure can exacerbate asthma and can be dangerous 

to persons with pre-existing cardiopulminary diseases. 

Thus monitoring near strong sources of SO2 (e.g. from 

industrial sources and at volcanoes) is important, as is 

longer term monitoring at some distance from the 

source. Currently there are no regulatory requirements 

for airport operators to provide warnings of ash 

hazards. Warnings are issued based on information 

from volcano observatories, meteorological advisories 

and, in some cases, radar observations of eruption 

columns. Radar information is generally only reliable 

at the start of an eruption when the ash cloud is thick 

and usually such information is only available at 

airports in close proximity to an erupting volcano. For 

airports distant from the source of ash there are few 

direct observations available. Some observations come 

from satellite systems and other sources of information 

come from trajectory forecasts based on wind data and 

cloud height information. Much of this information is 

sporadic and untimely and there is a need for better 

coordinated information systems and better 

observational systems. A detector placed on the ground 

at an airport affected by volcanic ash would provide a 

useful adjunct to existing information sources. The 

device would be capable of viewing the sky overhead at 

horizontal distances of several kilometers in all 

directions. Given that ash clouds and gases travel at 

the mean speed of the winds the system would provide 

crucial advance warning. For example, a cloud moving 

at 10 ms-1 (36 km hr-1 at an altitude of 3 km (~10,000 

feet) would be observed by the detector ~16 minutes 

before it appeared overhead. At 30 ms-1 (108 km hr-1) 

the warning time shortens to ~5 minutes. The G-bIRD 

system detects ash clouds by their unique signature in 

the infrared window between 8–12 μm (see Prata and 
Session 3 – Page 40 

Barton, 1993 for details). SO2 is detected by exploiting 

the absorption caused by the gas near 8.6 μm. 

Wind-blown dust from desert regions or semiarid lands 

can be a hazard to aircraft, reduces visibility 

significantly and can cause eye and throat irritation to 

humans. Large parts of the habitable earth are prone to 

dust storms, including northern Africa, the 

Mediterranean islands, southern Italy, Spain and 

France, southwestern USA, central and southern 

Australia, western parts of South America, central 

China, Japan and south and north Korea and the central 

deserts of Asia. The wind blown dust can also be 

transported long distances–dust from China has been 

detected in north America. The dust can consist of 

nearly spherical particles of SiO2 in concentrations that 

will limit visibility to a few 10's of metres. Fine (1-10 

μm diameter) particulates of SiO2-bearing minerals 

have characteristic absorption features (Restrahlen 

effects) in the region 8-9 μm and can be detected by GbIRD. 

Principle of operation. 

The Ground-based InfraRed Detector–G-bIRD (Prata 

and Bernardo, 2004; Prata, 2004) is a new passive 

thermal infrared imaging camera based on uncooled 

microbolometer technology and is a natural extension 

of earlier precision radiometers developed by Prata and 

Barton (1993) and Prata et al. (1991). The device 

operates by comparing infrared signals from the sky 

above, at up to 5 pre-defined wavelengths (the central 

wavelengths and wavelength intervals are given in 

Table 1). The infrared radiation measured by the 

detector is linearly proportional to the resistance change 

in the detector, which is recorded and logged by a 

signal processing unit. The instrument concept is made 

possible by the recent commercial availability of 

relatively cheap uncooled focal plane detector arrays 

(FPAs). An uncooled microbolometer staring array 

sensitive to radiation in the 6-14 μm wavelength 

interval is used to detect filtered radiation by use of a 

filter wheel (or similar mechanism). The radiation from 

the sky is focussed onto the array by means of 

focussing optics (a Ge lens or mirror) and the field-ofview is a cone of up to 90 degrees. The use of a filterwheel mounted with circular interference filters is an 

option. 

The G-bIRD camera 

The prototype G-bIRD camera consists of an uncooled 

focal plane infrared array of dimensions 320x240 

pixels, with F0.86 optics and a custom built filter wheel 

holding up to five narrow band (<1 μm width) 

interference filters. The detector has a nominal noise 

temperature of no less than ~50 mK in the broadband 

channel. To achieve sufficient temperature sensitivity 

in the narrow band channels, frame averaging is 

employed. Table 1 shows the theoretical noise 

equivalent temperatures (NE∆T's) expected for various 

frame averaging values in 5 narrow bands or channels 

and one broadband channel. 

Band 

(λ) 

High 

(λ) 

Low 

(λ) 

No of frames 

(NE∆T, mK) 

 4 16 32 64 

7.3 7.05 7.55 1346 476 337 238 

8.6 8.35 8.85 890 315 223 157 

10.1 9.85 10.35 643 227 161 114 

11.0 10.75 11.25 657 232 164 116 

12.0 11.75 12.25 900 318 225 159 

8-14 8 14 65 23 16 11 

Table 1. Noise equivalent temperatures (NE∆T, mK) 

for different amounts of frame averaging. 

Calibration 

The G-bIRD camera provides raw digital counts as 

output from the FPA; the output has some corrections 

applied. These counts can be related to the scene 

temperature through a linear calibration process. A two 

point blackbody calibration procedure was developed 

which uses the output from the FPA corresponding to 

two cooled and heated blackbody cavities placed in 

front of the lens. The combined effect of the filters and 

detector response is considered in the calibration 

procedure. No account has been taken of the effects of 

off-axis viewing through the filters and the filter 

responses are single measurements of the response of 

the central portion of the filter (50 mm diameter). To 

convert from the calibrated radiances to scene 

temperature, the calibration equation must be inverted. 

This is a nonlinear problem that requires a minimisation 

procedure. The approach adopted is to generate a series 

of look-up tables that give radiances equivalent to prespecified temperatures. The procedure is accurate to 10 

mK over the range of observable temperatures 220 K to 

330 K. The calibration procedure is repeated several 

times and average look-up tables are generated. In 

actual use the calibration is performed in the laboratory 

and not done in the field. This is possible because once 

a calibration file has been derived under idealised 

conditions this can be used in all future measurements 

to convert the raw signals into temperatures. However, 

in practice the optics (particularly the lens) may heat up 

or cool down and thus produce a different temperature 

to its value when calibrated in the laboratory. This 

causes an off-set in the measured signals. To overcome 

this problem we have devised an innovative field 

calibration procedure that makes use of a single shutter 
Session 3 – Page 41 

measurement. The shutter fills or slightly overfills the 

field-of-view of the instrument and provides a uniform 

radiation source to the detector. The temperature of the 

side of the shutter facing the lens is continuously 

monitored using a contact temperature probe. The 

shutter side facing the lens is blackened so that its 

infrared emissivity is high (exceeding 0.96) and 

uniform across the region 6-14 μm. In the field, the 

calibration is performed by making a single 

measurement of the shutter, followed by a measurement 

of the scene and then application of the calibration 

equations and shutter measurement that accounts for the 

off-set generated by any change in temperature of the 

lens. Fig. 1 shows a photograph of the camera in use in 

the field. 

Field Testing 

The G-bIRD camera has been field tested at several 

active volcanoes and sites where ash and SO2 emissions 

are observed. The complete field program, testing and 

analyses cannot be reported here and only a summary 

of the main results is given. 

Figure 1. The G-bIRD camera on site at Etna. 

The field program was divided into three parts: (A) 

testing of the camera hardware, processing system, 

communications and real-time image delivery, (B) 

testing the camera in elevated SO2 conditions, and (C) 

testing the camera in elevated volcanic ash conditions. 

To achieve the goals of the field program the following 

sites were visited: 

(1) Kilauea, Hawaii - system testing, 

(2) Anatahan, NMI - system testing and 

measurement site for goals (A, B, C), 

(3) Port Pirie, South Australia–SO2 measurements 

goal (B) 

(4) Etna and Stromboli, Italy–SO2 measurements 

and system test goals (A, B), 

(5) Tavurvur, Rabaul, PNG–ash measurements goal 

(C). 

To give an indication of the results of the trials we 

present data for field tests (4) and (5), which clearly 

show the usefulness of the system for volcanic SO2 and 

ash monitoring. 

Mt Etna and Stromboli, Sicily, Italy. Mt Etna (3300 m 

ASL) has been active since starting an eruptive phase in 

November 2002. The G-bIRD camera was deployed 

about 15 km from the active crater in the town of 

Nicolosi (1015 m ASL) on the south-western flank of 

the volcano. When measurements were made during 

September 2003, the emissions from Etna were 

predominantly SO2 with a few minor ash eruptions, 

never attaining significant height and rarely visible 

beyond a few 100 m's away. The viewing elevation 

angle of the camera was varied from 10 to about 30 

degrees above the horizon. The G-bIRD camera was 

tested for monitoring SO2 and for communications 

trials. At Stromboli, the emissions were also SO2 and 

the activity there provides a more or less continuous 

gaseous plume. Intermittent explosions of ash were 

observed, but these also rarely attained heights of more 

than a few 10's m above the summit and the ash did not 

get transported any significant distance in the air. GbIRD was mounted ~3 km from the active crater on 

Stromboli. Results are provided in Figures 2 and 3. 

Figure 2. SO2 plume observed over Mt Etna. The SO2

index is a qualitative measure of the SO2 concentrations 

in the plume. 

Each of the Figures shows a single frame of data 

identifying the plume as SO2-laden. Consecutive 
Session 3 – Page 42 

frames of data can be looped to form a movie-style 

animation of the plume. 

Figure 3. SO2 plume from Stromboli. 

These movies reveal typical plume dynamical features 

such as: thinning, turbulent eddies, puffs, fumigation 

and vertical and horizontal mixing. On many occasions 

G-bIRD detected large changes in the apparent 

concentrations of SO2; most notable were instances 

where the SO2 concentrations would dip below the 

detection level of G-bIRD and the plume appeared to be 

predominantly water vapour. A whole sequence of data 

was collected where a white-looking water-laden plume 

from Etna was indistinguishable to the naked eye (or a 

web-cam) from an SO2-laden plume. The G-bIRD 

imagery made a distinct discrimination between these 

two plumes. 

Figure 4. G-bIRD camera viewing a plume of SO2 and 

an explosion (coloured grey to black) from Stromboli. 

The results for Stromboli (Fig. 4) were similarly 

striking and unambiguous, although much less water 

vapour was apparent in the Stromboli plume and the 

strength of the SO2 signal was greater due to the closer 

proximity of the camera deployment there. That there 

is water vapour in both plumes is undeniable and 

obvious through observation of the white-coloured 

plumes from both volcanoes. Less obvious is the 

detection of separate regions of SO2 above the craters, 

where no plume is visible at all to the naked eye (or 

web-cam). Measurements were also made during the 

night at both volcanoes. If anything, the data are 

clearer during the night than during the day–the reason, 

perhaps, being due to less evaporation and subsequent 

lower water vapour loadings in the plumes at night 

compared to during the day. The G-bIRD camera was 

also able to capture discrete explosions from Stromboli. 

In the case of the explosion, the pyroclastic material is 

mostly hot rocks, cinders and ash and reveals itself as 

grey to black colours when the SO2 algorithm is used. 

In contrast when the ash algorithm is used, that is, by 

taking temperature differences using only two channels, 

the resulting image appears as shown in Figure 5. 

Figure 5. Ash algorithm used on an image with an 

explosion obtained at Stromboli. 

In this case the algorithm identifies the hot rocks and 

cinders as positive differences (high ash content), and 

resuspended ash as slightly negative (similar to the 

material on the surface of the mountain slopes). The 

sky has markedly negative differences. The 

interference effects of water vapour at these low 

elevation viewing angles has not been accounted for. 

There is a nonlinear relation between the temperature 

differences and the SO2 amount measured in atm-cm or 

other suitable units. This relation is of the form: 

u = ln [α ∆T + β], 

where α and β are parameters that depend on the 

absorption coefficient of SO2 around 8.6 μm and on 

instrumental characteristics. ∆T is a temperature 

difference formed between two channels and u is the 

absorber amount in suitable units. The parameters α

and β are determined from modelling studies and from 

calibration data for the instrument, including the 

response functions of each filter. An SO2 index has 

been derived to account for the minor nonlinearity and 

provide a fast, non-quantitative measure of the SO2

content in a G-bIRD image. Quantitative estimates of 

the SO2 loadings from the G-bIRD camera, while 
Session 3 – Page 43 

possible, were not attempted at Etna or Stromboli, 

principally because no independent validation data 

were acquired and the lack of a meteorological station 

close to the camera precludes accurate modelling of the 

interfering effects of water vapour. 

Tavurvur, PNG. The Tavurvur crater at Rabaul has 

been in near-continuous activity since the catastrophic 

and near simultaneous eruptions from Tavurvur and 

Vulcan on opposite sides of Rabaul harbour in 

September 1996. Tavurvur activity is characterised by 

ash-rich explosions occurring at intervals of between 

10-30 minutes. G-bIRD measurements at Tavurvur 

were conducted during 4 days in November 2003 from 

locations with line-of-sight of the crater and from 

distances of 1-10 km. A good example of ash 

identification is shown in Figure 6; Fig 7. Shows the 

corresponding visible camera image 

Figure 6. (a) Ash discrimination by G-bIRD for the 

Tavurvur plume (upper panel). (b) Visible camera 

image of the ash plume from Tavurvur, taken at almost 

the same time as the G-bIRD image (lower panel). 

Although present, SO2 was not detected by G-bIRD at 

Tavurvur. The reasons for this are thought to be due to 

the excessively high water vapour loadings, the 

interference from ash effects within the SO2 channel 

(~8.6 μm), and possibly the much lower SO2

concentrations (in comparison to H2O). Excellent 

results were acquired at the "hot springs" within 2 km 

of the crater and from Rabaul observatory, some 6 km 

distant. Beyond 10 km or so, identification became 

increasingly difficult due to obscuration by water 

vapour over such long path lengths. 

Variation with elevation 

In clear and cloudy skies when there is no ash or SO2

present, water vapour causes differential absorption of 

radiation in the atmospheric window between 6–14 μm. 

Theoretical calculations and modelling studies indicate 

that this difference will be negative when the camera 

views the sky above the horizon. The exact value of 

the difference depends on the amount of water vapour, 

but also on the path length that the radiation traverses 

through the atmosphere. Figure 7(a) shows the 

variation of the temperature difference (11–12 μm) with 

elevation for a cloudless atmosphere containing about 3 

cm of precipitable water. At low elevation angles the 

temperature difference is slightly negative, but gets 

progressively more negative until at around 60 degrees 

elevation when the difference decreases slowly. A 

consequence of this behaviour is that it is not possible 

to set a constant threshold for deciding whether GbIRD images contain ash-affected pixels 

Figure 7. (a) Variation of elevation angle with 

temperature difference (11-12 μm) for clear skies 

determined from radiative transfer modelling, and (b) 

the difference as determined from measurements made 

at Saipan. 

Figure 7(b) shows results using a series of G-bIRD 

images taken on Saipan island in clear skies. The 

variation with elevation angle mimics the theoretical 

behaviour. The same effect with elevation can be seen 

for 8.6–12 μm temperature differences, except that after 

60 degrees the difference starts to increase rather than 

decrease. This is not seen in the modelling results, and 

more data are required to determine the cause of this 

effect. These data show more variation than the 

theoretical studies because the scene also contains 

clouds and unmodelled water vapour variations. 

Nevertheless, the temperature difference decreases with 
Session 3 – Page 44 

elevation angle in all cases studied and agrees with the 

theoretical behaviour. 

Conclusions

G-bIRD is a new thermal imaging passive infrared 

camera capable of detecting SO2 and volcanic ash. The 

prototype camera has been successfully field tested at 

several active volcanoes and it has been demonstrated 

that SO2 and ash can be discriminated from 

meteorological clouds. Rapid imaging, remote, 

autonomous operation and secure communications have 

also been successfully achieved. The camera works 

well up to distances of ~10 km from the volcano. It 

provides information 24 hours a day in clear conditions, 

but can also work well in slightly cloudy conditions. 

During rain or snowfall or heavily overcast skies, GbIRD suffers the same limitations as other passive 

devices and may not provide reliable detection under 

these adverse circumstances. 

There remains some work to be done in assessing the 

quantitative value of the G-bIRD imagery, particularly 

with respect to SO2 concentrations. To this end, it 

would be most valuable to conduct field validations 

against established SO2 monitors (e.g. COSPEC or 

mini-DOAS devices). Laboratory and field 

investigations aimed at quantifying the minimum ash 

concentrations detectable by G-bIRD would also be of 

great value. Regardless of the ability of G-bIRD to 

quantify SO2 and ash, a rapid-imaging, thermal infrared 

camera for use at volcano observatories, ash-affected 

airports, and at the sites of active volcanoes seems 

warranted if timely hazard warnings of airborne 

volcanic emissions are required. 

References 

Cantor, R., Complete avoidance of volcanic ash is only 

procedure that guarantees flight safety, ICAO 

Journal, 53(7), 18, 1998. 

Casedevall, T. J., Proceedings of the First 

International Symposium on Volcanic Ash and 

Aviation Safety, USGS Bull. 2047, U.S. Geological 

Survey, Washington, DC, 450p, 1994. 

Guffanti, M., Casadevall, T., and Mayberry, G., 

Reducing Encounters of Aircraft with Volcanic Ash 

Clouds, This Volume. 

Prata, A. J. and I. J. Barton, Detection system for use 

in an aircraft, Australian Patent No PJ9518, 

European Patent No. 91907594.5, U.S. Patent No. 

5,602,543, 1993. 

Prata, A. J., Barton, I.J., Johnson, W., Kingwell, J., and 

Kamo, K., Hazard from volcanic ash, Nature, 354, 

25, 1991. 

Prata, A. J., Sulphur dioxide detection method. 

Australian Provisional Patent No. 2004900213, 

2003. 

Prata, A. J. and C. Bernardo, An infrared detection 

apparatus. Australian Provisional Patent No. 

2004900214, 2003. 

Tupper, A, Carn. S., Davey, J., Kamada, Y., Potts, R., 

Prata, A., and Tokuno, M., An evaluation of volcanic 

cloud detection techniques during recent significant 

eruptions in the western ‘Ring of Fire’, Remote 

Sensing Environ, 91, 27–46, 2004. 

Acknowledgements. This work was supported by Tenix 

Investments and Tenix Electronics Systems Division. We 

thank Nigel Basheer and Simon Langsford for their help with 

system design and field testing. Georgina Sawyer and Mike 

Burton provided generous assistance for the Etna field tests. 
P3.1 

Session 3 – Page 45 

UW-MADISON ADVANCED SATELLITE AVIATION-WEATHER PRODUCTS 

MODIS/AVHRR/GLI SATELLITE VOLCANIC ASH DETECTION 

Steven A. Ackerman*, Wayne F. Feltz*, Michael S. Richards*, Timothy J. Schmit@, 

Anthony J. Schriener*, John Murray#, and David Johnson%

* Cooperative Institute for Meteorological Satellite Studies (CIMSS), 

University of Wisconsin-Madison, Madison, WI @ NOAA/NESDIS, Office of Research and Applications, Madison, WI #

 NASA LaRC, Langley, VA % NCAR, Boulder, CO 

1. Introduction 

Geostationary satellite instrumentation offers 

relatively good temporal resolution for the 

monitoring of airborne ash resulting from volcanic 

eruptions. While geostationary platforms provide 

better temporal resolution, their large fields of 

view and limited global coverage over 

volcanically active regions act as disadvantages 

for the tracking of volcanic ash in the atmosphere. 

In contrast, polar orbiting satellites provide high 

spatial resolution and better global coverage but, 

in general, poor temporal sampling. At any given 

time there are several polar orbiting satellites, each 

capable of detecting volcanic ash with fairly 

frequent time intervals at upper latitudes. This 

ongoing study focuses on determining how best to 

optimize satellite platform and infrared channel 

selection from different IR instruments aboard 

satellites in both polar and geostationary orbits in 

an effort to better monitor volcanic ash in the 

atmosphere. 

This paper provides results obtained by Schreiner 

et al. during their investigation of upper-level SO2

monitoring by the current GOES sounder. A 

separate investigation of volcanic ash monitoring 

by the MODIS, NOAA AVHRR and the Japanese 

Global Imager (GLI) instruments is also presented. 

Both investigations focus on volcanic eruptions of 

Soufriere Hills on the island of Montserrat, located 

 

Corresponding author address: 

Steven A. Ackerman, CIMSS/SSEC, 

1225 West Dayton Street Room 251, 

Madison, WI, 53706 

stevea@ssec.wisc.edu 

in the eastern Caribbean, during the period 13-15 

July 2003. 

2. Methodology 

The methodology used in this research to detect 

the presence of volcanic ash plumes consisted of 

utilizing measurements from instruments onboard 

several polar orbiting satellites. These instruments 

include MODIS (Terra), AVHRR (NOAA 15, 16 

and 17) and GLI (ADEOS-II). The ash detection 

method used is based on knowledge of spectral 

signatures resulting from the presence of 

suspended particulates. These particulates 

produce spectral signatures caused by differential 

scattering, absorption and/or emission of infrared 

radiation by the plume constituents. The spectral 

signatures from the ash cloud are driven by the 

microphysical properties and index of refraction of 

the aerosols. Spectral measurements near 11 and 

12 μm have been successful at detecting these 

volcanic ash aerosols. 

Detection of SO2 can also be useful in monitoring 

ash clouds when SO2 is released along with ash 

during a volcanic eruption. While both SO2 and 

ash do not always follow the same post-eruption 

trajectories (Seftor et al. 1997), monitoring SO2

clouds does provide insight for locating possible 

regions of volcanic ash. Considering the 

aforementioned spectral signature methodology, 

spectral measurements at 7.3 and 8.5 μm have 

been successful at detecting volcanic plumes 

containing SO2. Both SO2 and volcanic ash 

detection examples from the Soufriere Hills 

volcanic eruption follows. 
Session 3 – Page 46 

3. Using the GOES Sounder to detect SO2

The first major eruption of Soufriere Hills 

occurred around 0230 UTC on 13 July. This 

eruption was triggered by a major collapse of the 

Soufriere Hills lava dome with the resulting ash 

cloud reaching a level of approximately 16 

kilometers1. A calculation of SO2 concentration 

(Dobson Units) based on AIRS radiance 

information (Figure 1) from 13 July at 1653 UTC 

shows that SO2 concentrations from the volcanic 

plume approached 300 milli atm-cm and extended 

towards the northeast from Monsterrat Island. 

Using a trajectory model (NOAA HYSPLIT 

Model), forward trajectories were calculated 

(Figure 2). Utilizing bands 10 (7.4 μm) and 5 

(13.3 μm) on the GOES sounder, a series of “band 

differenced” images (BT10-BT5) were derived 

(Figures 3-6). The derived images were obtained 

in order to subtract out the background 

temperature difference, since these two bands are 

“sensing” the same layer of the atmosphere. The 

resulting difference band shows the “SO2 plume” 

(dark areas) over an eighteen-hour period 

following the eruption. 

Figure 1: Calculation of SO2 concentration (Dobson Units) 

based on AIRS radiance information from 13 July at 1653 

UTC. Figure provided by Dr. Fred Prata CSIRO. 

 

1

 based on estimates from the Volcanic Ash Advisory 

Center in Washington, D.C. 

Figure 2: NOAA HYSPLIT 24 hour trajectory model 

beginning 00 UTC 13 July 2003. Figure provided by Dr. 

Fred Prata CSIRO. 

4. Using MODIS, AVHRR and GLI to Detect 

Volcanic Ash and SO2

Between the dates of 13-15 July 2003, numerous 

explosive events occurred at the Soufriere Hills 

volcano on Montserrat. During this period, ash 

was observed to have reached altitudes greater 

than 10 kilometers on more than one occasion2

. 

Instruments aboard polar orbiting satellites Terra, 

NOAA 15, NOAA 16, NOAA 17 and ADEOS-II 

were able to scan the Caribbean in the hours 

immediately following Soufriere Hills’s explosive 

volcanic activity. 

Presented here are images derived from the 

MODIS, AVHRR and GLI instruments. All 

instruments have channels near 11 and 12 μm, and 

the MODIS and GLI yield spectral measurements 

sensitive to SO2, near 8.6 and 7.4 μm. The 

following derived images show the polar orbiting 

 

2

 Smithsonian Institute – Global Volcanism Project 
Session 3 – Page 47 

13 July 2003 0720 UTC (figure 3)

13 July 2003 1320 UTC (figure 4)

13 July 2003 1920 UTC (figure 5)

14 July 2003 0120 UTC (figure 6)

Figures 3-6: GOES sounder images from 13-14 July 2003 

Images are sounder band 10 (~7.4 μm) minus sounder band 

5 (~13.3 μm).

satellites’ perspective of the Soufriere Hills’ 

eruptions from several different instruments and 

viewing angles. The series of MODIS (Figures 7-

8), AVHRR (Figures 9-11) and GLI (Figures 12-

13) images are band differenced (11-12μm) 

brightness temperatures. These so-called “splitwindow” channels are used to “observe and 

quantify silicate ash” (Elrod and Im 2003, Watson 

et al. 2004). Corresponding band subtractions for 

MODIS, AVHRR and GLI are 31-32, 4-5 and 35-

36, respectively. Negative differences in the band 

differenced images show likely locations for 

airborne volcanic ash. It should be noted that the 

changing satellite viewing geometries and 

instrument spectral response functions lead to 

instrument differences. 

Figure 7: MODIS (Terra) image from 1435 UTC 14 July 

2003. Images are band 31 (~11 μm) minus band 32 (~12 

μm). 

Figure 8: MODIS(Terra) image from 1515 UTC 15 July 

2003. Images are band 31 (~11 μm) minus band 32 (~12 

μm).
Session 3 – Page 48 

Figure 9: AVHRR(NOAA15) image from 1140 UTC 13 July 

2003. Images are band 4 (~11 μm) minus band 5 (~12 μm).

Figure 10: AVHRR(NOAA17) image from 1450 UTC 13 July 

2003. Images are band 4 (~11 μm) minus band 5 (~12 μm).

Figure 11: AVHRR(NOAA16) image from 1825 UTC 15 July 

2003. Images are band 4 (~11 μm) minus band 5 (~12 μm).

Figure 12: GLI(ADEOS-II) image from 15 July 2003. Images 

are band 35 (~11 μm) minus band 36 (12 μm). 

Figure 13: GLI(ADEOS-II) from 15 July 2003.

The advantage of GLI and MODIS measurements 

is that both instruments have channels at the 7.3 

and 8.5 μm region. This provides the ability to 

distinguish volcanic ash, clear, and cloudy scenes 

from one another as presented in figure 13. 

5. Conclusions and Future Work 

Instruments in both geostationary and polar orbits 

provide unique methods for the detection and 

tracking of volcanic ash in the atmosphere. 

Results by Schreiner et al. presented here reveal 

that the current GOES Sounder is able to detect 

upper-level SO2 over areas of normally low 
Session 3 – Page 49 

probabilities of volcanic eruption. In this case the 

sounder scan sector only provided a six hour 

temporal resolution. Optimally a high spatial and 

temporal resolution with spectral coverage in 

volcanically sensitive IR regions is desired. 

Trajectories illustrated in Figure 2 indicate the 

SO2 detected by the GOES sounder, a plume of 

relatively negative band differences (7.4-13.3μm) 

to the northeast of the island (Figures 3-6), might 

have existed at a height of approximately 15 

kilometers a.s.l. While AVHRR imagery (Figure 

9) does indicate the likely presence of a volcanic 

ash plume (relatively negative 11-12μm band 

difference) to the northeast of the island, the 

highest concentrations of airborne ash exist to the 

immediate south and west of the island (Figures 

9-10). As illustrated here, the polar orbiting 

platform provides a necessary compliment to 

geostationary instruments such as the GOES 

sounder when monitoring volcanic ash in the 

atmosphere. 

Future work includes optimizing the operational 

Geostationary and Polar infrared instrument 

(GOES and AVHRR) volcanic eruption detection 

algorithms to sense SO2, volcanic ash, and plume 

height. In fact, good estimates of volcanic ash 

altitude are not routinely available via satellite 

remote sensing systems and is a major concern to 

the aviation community. 

In addition, polar research satellites (MODIS, 

GLI, and AIRS) will be used to provide insight for 

improvement of volcanic ash tracking and 

dissipation rates for high latitude volcanic 

eruptions with emphasis places on determining the 

altitude of the volcanic ash cloud. 

The next generation geostationary infrared 

weather instruments (ABI, GIFTS and HES) will 

have spectral coverage similar to existing 

instruments on polar orbiting satellites. This 

investigation, therefore, provides an opportunity to 

lay the ground work for future “volcanic ash 

detection” algorithms. 

6. References 

Elrod, G. P. and J. Im, 2003: Development of 

Volcanic Ash Image Products Using MODIS 

Multi-spectral Data. Preprints, 12th Conference of 

Satellite Meteorology and Oceanography, 9-13 

February 2003. Boston, MA, American 

Meteorological Society, 

Schreiner A. J., T. J. Schmit, J. Li, G. P. Ellrod, 

M. Gunshor, and K. Karnauskas, 2004: Using 

GOES-R to Help Monitor SO2. Presented at the 

GOES-R Users Conference. 10-13 May, 2004. 

Broomfield, CO. 

Seftor, C. J., N. C. Hsu, J. R. Herman, P. K. 

Bhartia, O. Torres, W. I. Rose, D. J. Schneider and 

N. Krotkov, 1997: Detection of volcanic ash 

clouds from Nimbus-7/TOMS, J. Geophys. Res., 

102: 16749-16760. 

Watson, I. M., V. J. Realmuto, W. I. Rose, A. J. 

Prata, G. J. S. Bluth, Y. Gu, C. E. Bader and T. 

Yu, 2004: Thermal infrared remote sensing of 

volcanic emissions using the moderate resolution 

imaging spectroradiometer, J. Volcanol Geoth Res 

135: 75-89
P3.2 

Session 3 – Page 51 

REMOVAL PROCESSES OF VOLCANIC ASH PARTICLES 

FROM THE ATMOSPHERE 

Gregg J.S. Bluth and William I. Rose, Michigan Technological University 

INTRODUCTION 

 The use of satellite techniques provides 

valuable information for mapping ash hazards, as 

well as the means to study and predict the fates of 

volcanic clouds. We have used ultraviolet (TOMS 

– Total Ozone Mapping Spectrometer) and 

infrared (e.g., AVHRR – Advanced Very High 

Resolution Radiometer; HIRS2 – High Resolution 

Infrared Radiation Sounder/2; GOES – 

Geostationary Operational Environmental 

Satellite; MODIS – Moderate Resolution Imaging 

Spectroradiometer) satellite sensors to examine 

the solid, liquid and gas species in numerous 

volcanic clouds over the past 25 years. Each 

sensor provides a somewhat different perspective 

of volcanic clouds, depending on their spatial, 

spectral and temporal resolutions. Thus, when 

combined these techniques provide important 

constraints on the interactions and fates of species 

within the clouds. Quantitative infrared 

techniques can provide information on how the 

size, size distribution, and total mass of fine ash 

particles evolve as a cloud mixes with the 

atmosphere. Here we present a review of past 

relevant observations and research, and the results 

of ongoing satellite studies. 

VOLCANIC CLOUD PARTICULATES 

 Volcanic clouds are typically composed of a 

variety of particulates, derived from: 

 -volcanogenic sources (silicate particles, 

erupted gases and liquids) 

 -the atmosphere (water/ice, dust, sea salt, 

gases) 

 -products from volcano-atmosphere reactions 

(aerosols, coatings, adsorbed species on existing 

particles) 

(1) Particle compositions 

 -silicates: glassy pyroclasts and minerals, 

which represent the crystalline fraction of the 

magma. Their shapes are highly angular, and in 

fact can be composed of shards, bubble fragments, 

as well as microcrystals. The silicate particles 

reflect the magmatic origins, ranging from 

rhyolitic (high silica) to basaltic (low silica). 

 -non-silicates: the most common type is 

sulfate aerosols. Many other minor and rare 

phases have been observed (Rose et al., 1982). 

(2) Shapes and Sizes: 

A thorough examination of particle size, 

geometry, and composition by Riley et al. (2003) 

revealed: 

 -extremely high surface areas relative to 

volume, due to roughness and vesicularity (up to 2 

orders of magnitude greater areas than calculated 

using shape alone). 

 -aspect ratios of 1.5 – 2.6 (long-to-short 2D 

dimensions, compared to 1 for a perfect sphere). 

See Figure 1. 

Erupted materials are composed of a full 

spectrum of particle sizes, which quickly becomes 

differentiated through gravitational settling and 

physical interactions in the clouds. Based on 

satellite studies, about 1-2% of the total ash mass 

erupted is 1-12 microns (μm) in radius (Rose et al., 

2001), which is the fraction which can be most 

easily tracked by satellite. 

Figure 1. SEM photos of (l-r) Fuego, Guatemala basaltic ash; 

Mt. Spurr, Alaska andesitic ash; bubble wall shards from the 

rhyolitic ash of the Ash Hollow Member, Nebraska (Riley et 

al., 2003). Scale bars are 1000μm for Fuego, 100μm for Mt. 

Spurr and Ash Hollow Member.

THREE STAGES OF VOLCANIC CLOUD 

EVOLUTION 

 Rose et al. (2001) developed three general 

stages based on satellite observation of evolving 

clouds from the Mt. Spurr (Alaska) eruptions in 

1992: 
Session 3 – Page 52 

(1) High energy and growth 

During the eruption and for the first few hours 

afterward, the clouds resemble thunderstorms, and 

are often opaque to IR sensors. Most of the coarse 

(>50 microns diameter) material falls out near the 

vent source (Figure 2). 

Figure 2. This simple calculation (after Bonadonna et al., 

1998) shows that most large (>50 micron diameter) particles 

will fall out of a volcanic plume within the first day at rates of 

around 0.8 km/hr; on the other hand, very small particles (<1 

micron) could persist in the atmosphere for years. “Particles” 

may be composed of a single fragment; aggregates of various 

sizes; particles with coating of water or ice; particle with 

adsorbed gas or liquid. Clearly, the shape and density of a 

particle or group of particles will affect how it falls (laminar 

or turbulent), and how fast it will fall, but this calculation 

gives a rough estimate, assuming laminar flow and high 

latitude atmospheric conditions.

 

(2) Rapid physical and chemical changes 

Lasting approximately one day, the cloud 

expands in areal extent, but the optical depth and 

fine-particle size concentrations decrease rapidly 

(by 1 or more orders of magnitude). Fine ash is 

rapidly removed from the cloud, most likely by 

aggregation or as icy ash balls (see next section). 

(3) Drifting aircraft hazard 

This stage lasts 3-5 days, during which the 

cloud can move thousands of kilometers. Ash 

concentrations and optical depths decrease very 

slowly, and ash masses slowly decrease to below 

sensor detection limits. 

PARTICLE REMOVAL RATES 

 Table 1 compares the removal rates of ice and 

ash for several different eruptions. The 

measurement periods vary owing to instrument 

Table 1. Ash and ice removal rates measured 

by satellite 

Volcano Meas. 

Period 

(hrs after 

eruption)

Particle 

type 

Mean 

Removal 

Rate 

(kt/hr) 

Efolding 

(hrs) 

Sensor Ref

El 

Chichón, 

Mexico 

(1982a) 

5 – 68 ash 34 13 AVHRR a 

El 

Chichón, 

Mexico 

(1982b) 

7 – 70 ash 99 15 AVHRR a 

Pinatubo, 

Philippines 

(1991) 

5 - 111 ash 482 24 HIRS/2 b 

Pinatubo, 

Philippines 

(1991) 

5 - 111 ice 819 30 HIRS/2 b 

Pinatubo, 

Phillipines 

(1991) 

6 - 104 ash 363 27 AVHRR b 

Pinatubo, 

Philippines 

(1991) 

6 - 104 ice 648 27 AVHRR b 

Hudson, 

Chile 

(1991) 

2 – 132 ash 21.8 30 AVHRR c 

Spurr, 

USA (Jun 

1992) 

13 – 152 ash 2.3 143 AVHRR d 

Spurr, 

USA (Aug 

1992) 

14 – 84 ash 3.7 43 AVHRR d 

Spurr, 

USA (Sept 

1992) 

8 – 70 ash 4.9 52 AVHRR d 

Hekla, 

Iceland 

(2000) 

6 – 24 ice 48 8 AVHRR d 

Cleveland, 

USA 

(2001) 

6 – 20 ash 1.6 10 GOES + 

MODIS

e 

a) Schneider et al., 1999; b) Guo et al., 2004b; c) Constantine 

et al., 2000; d) Rose et al., 2001; e) Gu, 2004. 

1 micron 

10 microns 50 microns 

10 km

~ 0.8 km/hr

~ 0.01 km/hr 

~ 0.0003 km/hr

EFFECT OF SIZE ON FALLOUT 

RATES 

290 hours ground 3.3 years 11.5 hours

Time for a particle to reach the ground
Session 3 – Page 53 

temporal resolution, and the period reflects the 

time between when ash decrease is measured to 

the end of sensor detection. While this represents 

only a small portion of volcanic eruptions, it 

appears that the large events (El Chichón, 

Pinatubo, Hudson) exhibit fast removal rates of ice 

or ash and consequently much shorter residence 

times than the smaller events (Spurr, Hekla). 

However, note the exception from the Cleveland 

event, which was small, yet underwent rapid 

removal. In contrast to ash cloud decrease (efolding, which is the time for the cloud to reduce 

to 1/e of its original mass), sulfur dioxide gas efolding rates are on the order of 2 – 25 days, rather 

than hours (e.g., Figure 3). 

Figure 3. Mass removal patterns of ash, ice and sulfur 

dioxide in the 1991 Pinatubo volcanic cloud (Guo et al., 

2004a; 2004b). 

REMOVAL PROCESSES 

(1) Ash/ice hydrometeors 

Satellite studies find that the radii of 

suspended particles can increase over the first 36 

hours after eruption, which we interpret as 

indicative of ice formation on ash particles (Rose 

et al., 2000). Modeling studies suggest that these 

aggregates may be over 80% ash by weight (e.g., 

Herzog et al., 1998; Textor, 1999).

(2) Particle aggregation (sticking) 

 The rate of fine ash removal during the first 1-

2 days shows a rapid decrease (Figure 3), which 

cannot be explained through discrete particle 

settling rates (Figure 2). These fine particles must 

be removed by either adsorption onto larger 

particles or aggregation as a result of particle 

collisions.

REMOVAL RATES OF DIFFERENT CLOUD 

SPECIES 

 Note that in Figure 3 the ice and ash have 

similar removal rates, which are much faster than 

gas removal. Sulfur dioxide removal is largely a 

function of its chemical conversion rates to sulfate 

aerosol, rather than any kind of gravitational 

process. The resulting formation of sulfate aerosol 

is essentially the inverse of the gas decay. Other 

eruption clouds have shown similar patterns where 

fine ash removal is much faster than the sulfur 

dioxide gas (Table 1). The similarity of ice and 

ash removal rates, together with slow fallout 

calculated for discrete particles of this size, 

strongly suggest that both of these species undergo 

aggregation which drives their relatively rapid 

removal from the atmosphere. 

DOES ASH IN LARGE ERUPTIONS FALL 

OUT FASTER? 

 For Pinatubo, about 90% of the 1-15 micron 

sized ash fell out within the first 4 days of eruption 

(Figure 3). Approximately 99% of the fine ash 

was removed within 6 days. We have observed 

that several large eruptions have a significantly 

faster removal rate than smaller eruptions. How 

might this occur? 

(1) The more intense eruption columns typically 

involve greater upward velocities. These stronger 

events are therefore more efficient at re-entraining 

particles in the rising ash and gas plumes than 

low-intensity eruption columns (Ernst et al., 

1996). 

(2) More intense eruptions have higher eruption 

rates (volume emitted per time), so that the 

emitted volume of fragmented ash is higher. 

(3) More fragmentation, and a higher ash volume, 

results in more electric charge generated in the 

volcanic plume, producing more electrostatic 

“sticking” of particles. 

0

20

40

60

80

100

0 100 200 300 400

Time after eruption (hours)

Mass (Mt)

ICE

ASH

SO2 – HIRS/2

SO2 - TOMS
Session 3 – Page 54 

(4) Higher columns entrain more moist air and 

experience higher temperature gradients leading to 

the formation of hydrometeors, resulting in further 

charge generation by processes similar to electric 

charge formation in thunderstorms. 

(5) The combination of processes magnified by 

the more intense eruption columns produce more 

efficient particle removal by ash aggregation, ice 

coating and rapid removal as icy pyroclasts. 

CONCLUSIONS 

 Satellite sensors have the ability to detect and 

quantify the 1-12 micron radius size fraction of 

drifting volcanic ash clouds. Studies of removal 

rates and processes for a range of volcanic 

eruptions reveal that ash and ice particles fall out 

at much faster rates than do the co-emitted sulfur 

dioxide gas. The rapid fallout of fine particulates 

is best explained by aggregation processes, and in 

some cases, the formation of ice on ash particles. 

 

ACKNOWLEDGEMENTS 

Our satellite-based studies over the past 

several years have been supported by NASA’s 

Solid Earth and Natural Hazards program, NASA 

Headquarters, and the TOMS Science Team; and 

the National Science Foundation’s Petrology and 

Geochemistry program. 

REFERENCES 

Bonadonna, C., G.G.J. Ernst, and R.S.J. Sparks 

(1998) Thickness variations and volume 

estimates of tephra fall deposits: the 

importance of particle Reynolds number. J. 

Volc. Geotherm. Res., 81, 173-187. 

Constantine, E.K., G.J.S. Bluth, and W.I. Rose 

(2000) TOMS and AVHRR observations of 

drifting volcanic clouds from the August 1991 

eruptions of Cerro Hudson. AGU Geophys. 

Mon. 116, 45-64. 

Ernst, G.G.J., M.I. Bursik, S.N. Carey and R.S.J. 

Sparks (1996) Sedimentation from turbulent 

jets and plumes. J. Geophys. Res., 101, 5575-

5589. 

Gu, Y. (2004) Particle Retrieval Using Satellite 

Remote Sensing. Ph.D. thesis, Michigan 

Technological University. 

Guo, S., G.J.S. Bluth, W.I. Rose, I.M. Watson, and 

A.J. Prata (2004a) Re-evaluation of SO2 

release of the 15 June 1991 Pinatubo eruption 

using ultraviolet and infrared satellite sensors. 

Geochem. Geophys. Geosys., 5, Q04001, 

doi:10.1029/2003GC000654. 

Guo, S., W.I. Rose, G.J.S. Bluth, and I.M Watson 

(2004b) Particles in the great Pinatubo cloud 

of June 1991: The role of ice. Geochem. 

Geophys. Geosys., 5, Q05003, 

doi:10.1029/2003GC000655. 

Herzog, M.,H.-F. Graf, C. Textor, and J.M. 

Oberhuber (1998) The effect of phase changes 

of water on the development of volcanic 

plumes. J. Volc. Geotherm. Res., 87, 55-84. 

Riley, C.M., W.I. Rose and G.J.S. Bluth (2003) 

Quantitative shape measurements of distal 

volcanic ash. J. Geophys. Res., 108, n. B10, 

2504. 

Rose, W.I., R. Chuan, and D.C. Woods (1982) 

Small particles in plumes of Mount St. Helens. 

J. Geophys. Res., 87, 4956-4962. 

Rose, W.I., G.J.S. Bluth and G.G.J. Ernst (2000) 

Integrating retrievals of volcanic cloud 

characteristics from satellite remote sensors: a 

summary. Phil. Trans. Roy. Soc. London A, 

358, 1585-1606. 

Rose, W.I., G.J.S. Bluth, D.J. Schneider, G.G.J. 

Ernst, C.M. Riley, L.J. Henderson, and R.G. 

McGimsey (2001) Observations of volcanic 

clouds in their first few days of atmospheric 

residence: The 1992 eruptions of Crater Peak, 

Mount Spurr Volcano, Alaska. J. Geology, 

109, 677-694. 

Schneider, D.J. et al. (1999) Early evolution of a 

stratospheric volcanic eruption cloud as 

observed with TOMS and AVHRR. J. 

Geophys. Res., 104, 4037-4050. 

Textor, C. (1999) Numerical simulation of 

scavenging processes in explosive eruption 

clouds. Ph.D. thesis, Max Planck Institute for 

Meteorology, Hamburg, Germany. 
P3.3 

Session 3 – Page 55 

SOUNDING OF VOLCANIC CLOUDS WITH BALLOON-BORNE INSTRUMENTS: 

IMPROVING 

ALGORITHMS FOR ASH AND SO2 IN REMOTE SENSING IMAGERY 

John Chadwick, Idaho State University, Pocatello, ID, USA 

Zach Lifton, Idaho State University, Pocatello, ID, USA 

Ken Dean, University of Alaska, Fairbanks, AK, USA 

Jim Chadwick, Mitre Corporation, Mclean, VA, USA 

The Volcanic Ash Sulfur Dioxide Balloon Experiment (VASDBE) is a set of sampling 

instruments designed for rapid balloon-borne deployment into a volcanic cloud 24 – 96 hours 

after a large volcanic eruption. High precision instruments for measuring ash and sulfur dioxide 

concentrations, as well as meteorological parameters, will be used to characterize the 

atmospheric column from the surface to 32,000 m. The 4-6 balloon sensor platforms to be built 

will be tracked using GPS, and recovered after a parachute descent for data collection. For 

launch planning, volcanic clouds will be tracked using near real-time GOES imagery and 

meteorological prediction models such as Puff. The results of this study will be used to refine 

the calibration of algorithms for the measurement of ash and SO2 from remote sensing imagery, 

and will thus improve remote sensing based ash warnings for aircraft. GOES imagery is 

acquired every half-hour, and balloon launches can be synchronized with image collection with 

little temporal offset to allow for direct comparisons between imagery and sounding data. 

However, repeat cycles for polar-orbiting MODIS, TOMS, and ASTER platforms will render it 

more difficult to time balloon data collection to coincide with image acquisition. It is anticipated 

that this study will help to better constrain the viewing depths into volcanic clouds by various 

types of satellite imagery, and soundings near the periphery of the cloud will allow for the 

assessment of the minimum ash and SO2 concentrations that are detectable using remote sensing. 
P3.4

Session 3 – Page 57 

FALL3D: A NUMERICAL MODEL FOR VOLCANIC ASH DISPERSION 

IN THE ATMOSPHERE 

A. Costa, and G. Macedonio, Osservatorio Vesuviano - Istituto Nazionale di Geofisica e 

Vulcanologia, Napoli, Italy 

Aircrafts may unexpectedly encounter volcanic ash clouds during their flight that often cause 

engines failure. In order to mitigate the risk related to this accident it is of vital importance for 

public safety, the knowledge of the temporal evolution of the ash cloud dispersal. For these 

reasons reliable computational model are needed. Here, we propose a new Eulerian model, 

called FALL3D, for the simulation of dispersion and deposition of volcanic ashes. The model is 

based on the solution of an advection-diffusion-settling equation, coupled with a Limited Area 

Model (LAM) for the wind field, and a parameterization of the turbulent diffusivity tensor based 

on the K-theory. The equations are solved using a fully explicit third-order upwind scheme in a 

terrain-following coordinate system. The wind and temperature fields given by the LAM are 

assimilated to the finer scales using the meteorological processor CALMET. The procedure can 

be used for forecasting ash concentration from volcanic plumes in the atmosphere and ash 

loading on the ground. The input to the model are the topography, the meteorological field data 

as given by the LAM, the mass eruption rate and the settling velocity distribution of volcanic 

ashes in the source. A test application to the Etna 2001 volcanic eruption is presented. 
P3.5 

Session 3 – Page 59 

USE OF DISPERSION MODELS TO TRACK ERUPTION CLOUDS 

Ken G. Dean, Rorik A. Peterson, Ken Papp and Jonathan Dehn 

Geophysical Institute, University of Alaska Fairbanks, Koyukuk Dr., P.O.Box 757320, 

Fairbanks, Alaska 99775-7320, USA 

An overview of ash-tracking (dispersion) models will be presented, highlighting their strengths, 

weaknesses, and usefulness. The models are a tool for rapid response to predict the location, 

structure and movement of eruption clouds. Three models used in North America are Canerm 

(Montreal VAAC), Hysplit (Washington VAAC), and Puff (NWS Anchorage, AVO, U.S. Air 

Force Weather Agency, and universities). All three are similar in that they require gridded wind 

fields and specification of the initial eruption column size and shape. Wind fields are available 

with various spatial resolutions, time steps and geographical coverage. For operational eruption 

response, current wind fields are required. Dispersion models are initiated by releasing 

hypothetical particles above a volcano that are subsequently transported by advection, diffusion, 

and gravitational settling. The models diverge in their implementations of these transport 

mechanisms. Models must be fast, efficient, and easily configurable for diverse conditions, and 

they must approximate transport physics without becoming cumbersome. Model predictions are 

validated using satellite images, and are often "tuned" to match clouds observed on images. 

However, recent observations from the Mt. Cleveland eruption suggest that model predictions 

may be accurate when satellite images do not detect airborne volcanic material. In general, 

tracking models have been accurate for moderate altitude plumes (5 km to 16 km), and have had 

limited success with low and high altitude plumes (<5 km, and > 16km) and in situations with 

complex ground-relief. Some causes of these limitations are difficulties in accurately modeling 

diffusion in the near-surface boundary layer and lack of wind data in stratospheric regions. The 

accuracy of the models depends upon the accuracy of the wind fields, which can be variable 

between climate models. Furthermore, their course space and time resolution of many wind 

fields creates difficulties for short-term and nearby hazard forecasts for local communities in the 

immediate vicinity of a volcano. 
P3.6 

Session 3 – Page 61 

LABORATORY MEASUREMENTS OF HETEROGENEOUS ICE NUCLEATION BY 

VOLCANIC ASH: IMPORTANCE FOR DETECTING AND MODELING VOLCANIC CLOUDS

Adam J. Durant, Department of Geological Engineering and Sciences, Michigan Technological 

University, Houghton, Michigan, USA, [ajdurant@mtu.edu] 

Raymond A. Shaw, Department of Physics, Michigan Technological University, 

Houghton, Michigan, USA 

Youshi Mi, Department of Physics, Michigan Technological University, 

Houghton, Michigan, USA 

William I. Rose, Department of Geological Engineering and Sciences, 

Michigan Technological University, Houghton, Michigan, USA 

Analysis of brightness temperature difference images from thermal infrared measurements on 

meteorological satellites is a primary method that VAACs around the globe use for detecting 

volcanic ash clouds and mitigating hazards to aviation. A significant proportion of volcanic 

cloud particles are ice, and ice may conceal the characteristic spectral absorbance features of ash, 

making detection challenging. Cloud processes (e.g., lifetime, radiative properties) are sensitive 

to the competing effects of heterogeneous and homogeneous ice nucleation. We have designed a 

laboratory experiment that investigates heterogeneous ice nucleation, concentrating on ice 

formation on volcanogenic particles. The statistical nature of heterogeneous ice nucleation can 

provide insight into the physical mechanisms responsible for ice formation. In our experiments, 

we measure the freezing temperature for a single ice nucleus (IN) in a water drop hundreds of 

times to obtain detailed estimates of the probability density functions (PDFs) for freezing time 

(or temperature). The PDFs can be compared to the idealized inhomogeneous Poisson process 

based on the classical model of heterogeneous ice nucleation. We frequently observed a 

variation in freezing temperature of an IN between two ‘modes’, representing surface versus 

immersion freezing: the freezing temperature for the surface mode is ~5 K higher than the 

immersion mode. The distribution of freezing temperatures is nearly identical in both instances, 

suggesting the physical mechanisms for ice nucleation are not fundamentally different. Our data 

support the hypothesis that distinct interfacial and bulk nucleation rates exist for water. We 

speculate that the total nucleation rate is the sum of a nucleation rate corresponding to the 

interaction of bulk water with the IN, and a nucleation rate corresponding to the interaction of 

water at the surface of the drop (i.e., interfacial water) with the IN. Our measurements may have 

application in the representation of ice formation in models of volcanic plume dynamics. 
P3.7 

Session 3 – Page 63 

VOLCANIC ASH DETECTION AND CLOUD TOP HEIGHT ESTIMATION 

FROM THE GOES-12 IMAGER: COPING WITHOUT A 12μm INFRARED BAND

Gary P. Ellrod1, Anthony J. Schreiner2, and Alonzo M. Brown3

1

 Office of Research and Applications (NOAA/NESDIS), Camp Springs, MD 2

 Cooperative Institute for Meteorological Satellite Studies (CIMSS), University of Wisconsin, Madison, 3 Washington Volcanic Ash Advisory Center (NOAA/NESDIS), Camp Springs, MD

1. INTRODUCTION 

On 1 April 2003, Geostationary Operational 

Environmental Satellite (GOES)-12 replaced GOES-8 

as the primary spacecraft to monitor weather and 

environmental hazards over North and South America. 

Hillger et al 2003 describe the GOES-12 data and 

products and assess their quality. A major change to the 

GOES-12 Imager was the replacement of a 4 km 

resolution 12μm Infrared (IR) band with a lower 

resolution (8 km) IR band centered near 13.3μm (see 

Table 1). The 12μm band will not be restored until 

about 2013 when the GOES-R spacecraft becomes 

operational. There has been a concern that the loss of 

the 12μm band will negatively affect volcanic ash 

detection and aviation safety for the next ten years, 

since that channel has been effectively used in a twoband “split window” technique (Prata 1989) for over a 

decade. An impact study (Ellrod 2004) has indicated 

that there will likely be some degradation of volcanic 

ash detection, leading to both under-detection of thin 

ash, and an increase in the area of “false” ash, resulting 

in possible over-warning for aviation advisories. 

 

GOES 8-11 GOES M-P 

Band 

Wavelength 

( m) 

Res. 

(km) 

Wavelength 

( m) 

Res. 

(km) 

1 0.6 1 0.6 1 

2 3.9 4 3.9 4 

3 6.7 8 6.5 4

4 10.7 4 10.7 4 

5 12.0 4 - -

6 - - 13.3 8 

Table 1. Summary of GOES Imager spectral bands 

showing changes in the new series (M-P) in bold, 

compared with previous spacecraft (GOES 8-11). 

 The first significant opportunity to evaluate 

GOES-12 volcanic ash detection capabilities occurred 

with several moderate eruptions of Soufriere Hills 

Volcano on the island of Montserrat in the Eastern 

Caribbean from 12-15 July 2003. The eruptions were 

triggered by a major lava dome collapse, followed by 

pyroclastic flows (Montserrat Volcano Observatory 

2003). Ash was dispersed throughout the troposphere 

across the region, with maximum ash top heights 

estimated to range from 8-16 km (Washington Volcanic 

Ash Advisory Center (W-VAAC)). The VAACs were 

established during the mid 1990’s as part of the 

International Airways Volcano Watch (IAVW) to 

provide current advisories on existing volcanic ash 

clouds. Regional Meteorological Watch Offices then 

issue warnings (known as SIGMETs) to en route 

aircraft that are based on the VAAC advisories. The WVAAC has responsibility for the Caribbean region, as 

well as large portions of North and South America, and 

the Central and Western Pacific (International Civil 

Aviation Organization, 2000). 

2. VOLCANIC ASH DETECTION METHODS 

Traditional methods for detection of volcanic 

ash often employ a bi-spectral technique based on the 

brightness temperature difference (BTD) of two 

Infrared (IR) bands centered near 11.0 and 12.0 μm 

(Prata 1989; Holasek and Rose 1991). These two IR 

bands have been available at 1 km resolution from the 

Advanced Very High Resolution Radiometer (AVHRR) 

on the polar orbiting National Oceanic and Atmospheric 

Administration (NOAA) satellite series since the early 

1980's. By the mid 1990s, similar spectral bands also 

became available on the GOES. Although the spatial 

resolution of GOES IR sensors is only 4 to 8 km, their 

advantage is frequent coverage (nominally 30 min) over 

most volcanically active regions of North and South 

America, as opposed to four times daily from the 

AVHRR. 
Session 3 – Page 64 

 The two-band difference method (hereafter 

referred to as the Two-Band Split Window (TBSW)) 

sometimes fares poorly however, due to: (1) the 

excessive thickness of the eruption cloud, which often 

contains copious amounts of water and large ejected 

particles within a few hours after the eruption, (2) a lack 

of temperature contrast between the airborne ash and 

underlying surface, and (3) ambient atmospheric 

moisture that can mask low level ash clouds (e.g. 

Simpson et al 2000). Despite these shortcomings, the 

TBSW technique has become an international 

benchmark for volcanic ash detection. The loss of this 

channel on GOES-12 created the urgent need for a 

different approach. 

The altitude of the ash cloud is also important 

to aviation, and estimates of the top of the ash layer are 

provided in the VAAC messages. At the W-VAAC, the 

ash cloud heights are determined by matching the 

trajectory of different portions of the ash cloud with 

upper level wind profiles obtained from adjacent 

radiosondes or numerical prediction models. In this 

paper, we will describe new techniques for detecting 

volcanic ash clouds and estimating their maximum 

heights using the new spectral band combination 

available from the GOES-12 Imager. 

3. GOES-12 IMAGER ASH DETECTION 

ALGORITHM 

A new technique has been developed to detect 

ash from GOES-12 Imager Infrared (IR) brightness 

temperature (BT) data, using an arithmetic combination 

of Bands 2 (3.9μm), 4 (11μm) and 6 (13.3μm). Bands 

6 and 4 can help discriminate volcanic ash from iceladen cirrus cloud layers due to emissivity differences at 

those wavelengths (Ellrod 2004). Thermal differences 

between Bands 2 and 4 have been used in a three-band 

method (Ellrod et al 2003) which exploits reflectivity 

and absorption effects near 3.9 μm. The GOES-12 

algorithm was empirically determined using NASA 

MODerate resolution Imaging Spectroradiometer 

(MODIS) data (Ellrod and Im 2003) and GOES 

Sounder data. The new algorithm is: 

B = 5 (T2 – 1.5T4 + 1.5T6) – 230 (1) 

Where B is output brightness count, T2 is the BT 

observed in Band 2 (3.9μm), T4 is BT in Band 4 

(10.7μm) and T6 in BT in Band 6 (13.3μm). Volcanic 

ash is relatively bright (large values of B) compared to 

surrounding clouds and terrain volcanic ash. Thresholds 

for volcanic ash detection using this new approach have 

not yet been established due to the diurnal variation of 

T2. Even in bright daytime scenes, the ash clouds stand 

out against the background if they are sufficiently dense 

(see Figure 2). The plot in Figure 1 shows brightness 

count (B) from Equation (1) obtained on 14 July 2003 

at 0915 UTC (0515 Caribbean Standard Time (CST)) 

for several different types of features. The volcanic ash 

(solid circles) is clearly distinguishable from the cirrus 

(open triangles), mid-level clouds (stars), and ocean 

(diamonds) at this time. Note that if only thermal IR 

data are used, the ash would be virtually 

indistinguishable from other cloud types in the region 

due to similar brightness temperatures. 

Figure 1. Scatter plot of brightness count from 

Equation 1 versus IR band 4 from GOES-12 on 14 July 

2003 at 0915 UTC for volcanic ash, ocean surface, 

cirrus clouds, and mid-level clouds. 

The three-band technique was evaluated for 

three of the four Soufriere Hills eruptions. For 

validation and comparison, graphical ash analyses from 

W-VAAC were available, as well as imagery and 

derived products from the GOES Sounder. The 

Sounder is an independent instrument that employs a 

different scanning strategy, with the goal of producing 

temperature and humidity profiles (retrievals), as well 

as image products such as cloud top pressures (CTP), 

total precipitable water (TPW), and Lifted Index 

(Menzel et al 1998). The GOES Sounder has nineteen 

spectral bands, with a resolution of 10 km at nadir 

compared with 4-8 km for the Imager. For the Eastern 

Caribbean, Sounder data were only available at 0120 

UTC, 0720 UTC, 1320 UTC and 1920 UTC. The 

GOES-12 Sounder includes the same spectral bands as 

the Imager (except for the water vapor channel), but 

they are slightly narrower spectrally. 
Session 3 – Page 65 

4. CASE I: 12-13 JULY 2003 EVENT 

Triggered by a major collapse of the Soufriere 

Hills lava dome, first eruption occurred late on the 

evening of 12 July 2003 (around 0230 UTC, 13 July 

2003). The resulting ash cloud reached 15.7 km based 

on an IR estimate by the Washington VAAC. The 

development, expansion, and northeastward drift of 

cold cloud tops associated with the eruption column 

could easily be seen in GOES-12 Band 4 thermal IR 

images. However, the three-band IR product described 

in Section 2 was not effective, probably due to 

extensive water in the eruption cloud, and because high 

level non-volcanic clouds in the area obscured most of 

the dissipating ash. This is a common weakness of IR 

detection techniques (see Section 2). Minimum cloud 

top temperatures were around 200K for several hours 

following the eruption. Later confirmation of a volcanic 

ash cloud came from the Total Ozone Mapping 

Spectrometer (TOMS) at around 1530 UTC that day 

(not shown), which indicated that there were large 

concentrations of high altitude SO2 gas to the northeast 

of the Leeward Islands (image available from the 

NASA TOMS archive: 

http://skye.gfsc.nasa.gov/archives.html ). 

5. CASE II: 14 JULY 2003 EVENT 

Shortly after Midnight on 14 July 2003,

another release of ash occurred, with maximum cloud 

top heights estimated by the VAAC to be 11.3 km. 

Minimum T4 cloud top temperatures for this event were 

about 238K at 0615 UTC, but quickly became warmer 

as the cloud thinned out. For this case, there was less 

cloud cover in the region, allowing an evaluation of 

multi-spectral ash detection techniques. An hourly 

sequence of the three-band IR images depicted the midupper level ash cloud as it drifted toward the west and 

northwest. Lower level ash was more difficult to 

distinguish against the ocean background. 

6. CASE III: 15 JULY 2003 EVENT 

On 15 July 2003 at approximately 0530 UTC, 

the fourth eruption in this series sent ash to as high as 

47,000 ft (14.7 km) as reported by the Washington 

VAAC. The minimum cloud top temperature (T4) was 

224K at 0645 UTC. Figure 2 provides a two-hour 

interval sequence of three-band IR images showing the 

spread of the eruption clouds from 0745 UTC to 1345 

UTC. The ash cloud, the background ocean, and 

Figure 2. Two- hourly interval GOES-12 three-band IR volcanic ash product images showing evolution of ash on 

15 July 2003 from 0745 UTC to 1345 UTC. 
Session 3 – Page 66 

Figure 3. Volcanic ash product (based on the 3.9, 10.7 and 13.3 μm bands) from the GOES-12 Imager (left) at 

1245 UTC compared with the same product from the Sounder at 1320 UTC (center), versus a two-band difference 

based on the 12.0 and 11.0 μm channels from the Sounder, also at 1320 UTC (right). 

meteorological clouds all brighten around 1145 UTC 

due to solar reflectance in the 3.9 μm IR band. 

7. CLOUD TOP HEIGHT ESTIMATION 

The availability of the 13.3 μm IR band from 

the Imager on GOES-12 and its successors provides 

the capability of estimating volcanic ash cloud top 

heights with a CO2 Absorption Technique (COAT) 

(Schreiner and Schmit 2001; Schreiner et al 2002). 

Cloud Top Pressure (CTP), Effective Cloud Amount 

(ECA), and other derived products have been available 

hourly from the GOES Sounder for a number of regions 

since the mid-1990's (Menzel et al 1998). The COAT is 

a physical relationship based on a special version of the 

Radiative Transfer Equation. The main assumptions are 

(1) cloud is opaque but infinitesimally thin (thus 

allowing application for semi-transparent clouds), and 

(2) emissivity is the same in both spectral ranges. The 

latter assumption, when applied to the 13.3 μm and 10.7 

μm bands, is only valid when a volcanic cloud is at least 

partially composed of ice. 

 A comparison of a GOES cloud height analysis 

from 14 July 2003 at 0545 UTC with the VAAC 

graphical height analysis is shown in Figure 4. Based 

on subjective, textural evaluation of IR data, the high 

level ash was nearly opaque, while the low-mid level 

ash was semi-transparent. Cloud top heights from the 

GOES-12 product ranged from 7.6 km (24 kft) for the 

mid-level ash, to about 11.1 km (35 kft) for the high 

level ash, in good agreement with the VAAC analysis 

(based on an independent technique described in section 

2). 

Figure 4. Cloud top height product based on the 

GOES-12 Imager CO2 Analysis Technique (COAT) 

(top) compared with the VAAC analysis both valid 0545 

UTC, 14 July 2003. 
Session 3 – Page 67 

8. SUMMARY AND CONCLUSIONS

The first significant volcanic eruptions 

observed by the new GOES-12 satellite occurred from 

12-15 July 2003 following a lava dome collapse at the 

Soufriere Hills Volcano, Montserrat. A new IR 

technique that used the 3.9, 10.7 and 13.3 μm channels 

(Bands 2, 4, and 6) was able to observe the ash clouds 

effectively for two of the events during the period, 

while the strongest event could be monitored by a 

sequence of Band 4 IR images. Ash cloud heights 

based on the CO2 Absorption Technique for the 14 July 

2003 case were consistent with those from the VAAC 

analysis, which employs an independent wind trajectory 

matching technique. The uniformly warm ocean 

background, which provided excellent thermal contrast 

with the airborne ash clouds, was an advantage for 

observing these events which will not be present for 

some Continental volcanoes. The presumption that there 

would be under-detection and increased false alarms for 

ash detection using GOES-12 was not observed for this 

particular event. While the loss of the 12 μm IR band is 

likely to degrade the overall volcanic ash detection 

capability somewhat, this episode shows that imagery 

from GOES-12 and its successors will still be an 

effective means of warning pilots of hazardous ash 

clouds in many situations. 

9. REFERENCES 

Ellrod, G. P., (2004): Loss of the 12μm “Split Window” 

Band on GOES-M: Impacts on volcanic ash detection. 

J. Volc. Geothermal Res., Elsevier, Inc., Vol. 135/1-2, 

pp 91-103. 

__________, B. H. Connell, and D. W. Hillger, (2003): 

Improved detection of airborne volcanic ash using 

multispectral infrared satellite data. J. Geophys. Res., 

108(D12), 4356. 

__________, and J-S. Im, (2003): Development of 

volcanic ash image products using MODIS multispectral data. 12th AMS Conference on Satellite 

Meteorology and Oceanography, 9-13 Feb 2003, Long 

Beach, California 

Hillger, D. W., T. S. Schmit and J. Daniels, (2003): 

Imager and Sounder Radiance and Product Validations 

for the GOES-12 Science Test, NOAA Technical 

Report 115, U.S. Department of Commerce, 

Washington, DC, URL: 

http://www.cira.colostate.edu/ramm/goesm/GOES12_Science_Test_Report.htm 

Holasek, R. E., and W. I. Rose, (1991): Anatomy of 

1986 Augustine eruptions as revealed by digital 

AVHRR satellite imagery. Bull. Volcanol., 53, 420-

435. 

International Civil Aviation Organization (ICAO), 

(2000): Handbook on the International Airways 

Volcano Watch (IAVW): Operational Procedures and 

Contacts List, First Edition ICAO Doc. 9766-AN/968. 

Menzel, W. P., F. Holt, T. Schmit, R. Aune, A. 

Schreiner, G. Wade, and D. Gray, (1998): Application 

of GOES-8/9 soundings to weather forecasting and 

nowcasting. Bull. Amer. Meteor. Soc., 79(10), 2059-

2077. 

Montserrat Volcano Observatory, (2003): Summary of 

the 12-15 July 2003 dome collapse and explosive 

activity at the SoufriPre Hills Volcano, Montserrat. 

URL: http://www.mvo.ms/

Prata, A. J., (1989): Observations of volcanic ash 

clouds in the 10-12 micrometer window using 

AVHRR/2 data. Int. J. Remote Sens., 10, 751-761. 

Schreiner, A.J., T.J. Schmit, and R.M. Aune, (2002): 

Maritime inversions and the GOES Sounder cloud 

product, National Weather Digest, 26, 27-38. 

____________ and T.J. Schmit, (2001): Derived Cloud 

Products from the GOES-M Imager, Preprints, 11th 

Conference on Satellite Meteorology and 

Oceanography, Madison, Wisconsin, Amer. 

Meteor.Soc., 420-423. 

Simpson, J. J., G. Hufford, D. Pieri, and J. Berg, 

(2000): Failures in detecting volcanic ash from a 

satellite-based technique. Remote Sens. Environ., 72, 

191-217. 

Washington Volcanic Ash Advisory Center, (2003) 

Operational Volcanic Ash Advisories (VAA) 

for 2003 are available from: 

http://www.ssd.noaa.gov/VAAC/ARCH03/archive.html 
P3.8 

Session 3 – Page 69 

RESUSPENSION OF RELIC VOLCANIC ASH AND DUST FROM KATMAI: 

STILL AN AVIATION HAZARD 

David Hadley, NWS Alaska Aviation Weather Unit, Anchorage AK, USA 

Gary L. Hufford, NWS Alaska Region Headquarters, Anchorage AK, USA 

James J. Simpson, Scripps Institution of Oceanography, University of California, San Diego 

La Jolla, CA, USA 

Northwest winds were strong enough to continuously resuspend relic volcanic ash from the 

Katmai Volcano Cluster and the Valley of Ten Thousand Smokes on 20-21 September 2003. 

The ash cloud reached over 1600 m and extended over 230 km into the Gulf of Alaska. Several 

factors influenced the resuspension of the ash: (1) the atmosphere and land surface were very dry 

prior to the event, further enabling the resuspension and subsequent atmospheric transport of the 

relic volcanic ash; (2) production of winds strong enough to entrain and lift the ash over 1600 m 

into the atmosphere; (3) complex terrain with numerous mountains interspersed with valleys, 

channels and gaps; (4) super adiabatic lapse rate for the troposphere below 850 mb; and (5) the 

presence of a strong subsidence inversion around 1400-1600 m. We propose that the strong 

winds are due to accelerations in a super adiabatic atmosphere below 850 mb that is buoyant to 

both upward and downward perturbations resulting in a hydraulic flow that exposes the lee side 

of the mountains to sweeping, high speed turbulent winds near the base of the lee slope. Some 

unique features of the ash cloud are also examined, including its hazardous nature to aviation. 

Finally, this presentation provides the forecaster with the ability to: (1) recognize the conditions 

needed for relic volcanic ash resuspension; and (2) respond immediately to such an event. 

 
P3.9 

Session 3 – Page 71 

OBSERVING POPOCATEPETL’S VOLCANIC ASH CLOUDS USING 

MODIS INFRARED DATA 

M. Alexandra Matiella, Department of Geological Engineering and Sciences, Michigan 

Technological University, Houghton, MI, USA [mamatiel@mtu.edu] 

Hugo Delgado-Granados, Instituto de Geofisica, Universidad Nacional Autonoma de Mexico 

(UNAM), Mexico 

William I. Rose, Department of Geological Engineering and Sciences, Michigan Technological 

University, Houghton, MI, USA 

I. Matthew Watson, Department of Geological Engineering and Sciences, Michigan 

Technological University, Houghton, MI, USA 

Popocatepetl Volcano, Mexico, is a tropical volcano with significant and persistent emissions of 

SO2 and ash that pose significant hazards to the large population in close proximity to the 

volcano. The country’s main international airport, located approximately 55 km northwest of 

Popocatepetl in Mexico City, services about 800 flights a day and 20 million passengers a year. 

A large eruption of volcanic ash from Popocatepetl could devastate the city of 8 million 

inhabitants and shut down Mexico City’s international airport. Moderate Resolution Imaging 

Spectroradiometer (MODIS) satellite imagery provides us with a synoptic perspective of 

volcanic emissions and atmospheric interactions, information unavailable from ground-based or 

aircraft studies, which can be useful for hazard mitigation. Ash masses are retrieved using 

silicate absorption features at 11 μm and 12 μm. A suite of MODIS images was collected for a 

period of increased activity during December 2000 – January 2001. One particular image 

collected January 23rd, 2001, at 0450 UT, shows four large eruptions that have dispersed 

volcanic clouds over an extensive area of Mexico. Using upper air data and monitoring records, 

the movements of the 4 ash clouds are fit with eruption times and winds, and using retrieval data 

for ash we can derive a time based fine ash emission record. The results of these retrievals 

complement ground-based measurements which cannot measure large scale ash eruptions into 

the atmosphere and provide a possible scenario for the amount of time it would take a large ash 

cloud to reach Mexico City. 
P3.10 

Session 3 – Page 73 

COMPARISON OF ASH DETECTION TECHNIQUES USING TOMS, 

MODIS, AVHRR, AND GMS: A CASE STUDY OF THE AUGUST 18 AND 28 ERUPTION 

CLOUDS OF MIYAKEJIMA VOLCANO, JAPAN 

Emily McCarthy, Gregg Bluth, I. Matthew Watson, Michigan Technological University 

Andrew Tupper, Darwin Volcanic Ash Advisory Center 

Yasuhiro Kamada, Tokyo Volcanic Ash Advisory Center 

Introduction 

 Volcanic eruptions can eject ash, sulfur 

dioxide, and other gases into the atmosphere. 

Ash eruptions have been recognized as a 

serious aviation hazard, including engine failure, 

electronic failures, and poor visibility. Remote 

sensing techniques allow long-term tracking of 

volcanic clouds, analysis of eruptions in isolated 

areas, and measurements of an entire eruption 

cloud. Both ultraviolet (TOMS) and infrared 

(MODIS, AVHRR, and GMS) satellite sensors 

are capable of detecting volcanic ash. However, 

IR sensors are susceptible to interference of 

water vapor. Since each sensor uses different 

wavelengths their ability to detect volcanic 

clouds varies. For example, ash clouds may be 

seen using one IR sensor for several days and 

only one day using another. Therefore, this 

project also aims to understand and explain the 

limitations of each satellite sensor in detecting 

volcanic ash. The moist atmosphere of 

Miyakejima presents an opportunity to examine 

their sensitivity to atmospheric water vapor. Ash 

mass retrievals without a water vapor correction 

are compared to those run after the effects of 

water vapor are removed from the system. The 

mass, extent, and height of the cloud are 

important factors when considering the 

mitigation of aviation hazards. In this case study 

of Miyakejima Volcano, Japan, data from four 

different satellite sensors are compared and 

used to produce constraints on the masses and 

distributions of ash released by the August 18 

and 28, 2000 eruptions. 

Miyakejima Background 

 Miyakejima, a basaltic andesite stratovolcano, 

rises to an elevation of 813 m. Part of the IzuBonin volcanic island chain, Miyakejima is 

located about 200 km south of Tokyo (Figure 1). 

The summit consists of two calderas, 

Kuwakidaria and Hatchodaria, and a central 

cone. Mount Oyama (Geshi et al., 2002). 

Recent activity began in June of 2000 with small 

submarine eruptions and continues today with 

high emissions (average of 11,000 tons/day) of 

sulfur dioxide (Kinoshita et al., 2002). Several large 

eruptions occurred on August 18 and 28, 2000. In 

September 2000, the island was completely 

evacuated and remains uninhabited. Monitoring 

responsibilities are shared between the Japan 

Meteorological Agency (JMA) and the Tokyo 

Volcanic Ash Advisory Center (VAAC). All 

observations are made remotely through the use of 

satellites and video monitoring. SO2 measurements 

are taken monthly with the COSPEC. 

 The 18 August eruption at 08:02 UTC emitted an 

ash and SO2 cloud with a height of approximately 15 

km, moving south. The 28 August eruption (19:35 

UTC) was smaller with the ash and SO2 cloud 

reaching 9 km and moving northeast. 

Figure 1. A map of the major volcanoes of Japan. 

Miyakejima is located about 200 km south of Tokyo 

in the Izu-Bonin volcanic island chain. 
Session 3 – Page 74 

Methods 

The Volcanic Ash Retrieval. The infrared 

channels 4 (11μm) and 5 (12μm) of AVHRR and 

channels 31 (11μm) and 32 (12μm) of MODIS 

are used to discriminate volcanic clouds from 

meteorological clouds. Volcanic clouds 

generally have a negative brightness 

temperature difference (BTD) when the 12 μm 

channel is subtracted from the 11 μm channel, 

while meteorological clouds generally have a 

positive BTD (Wen and Rose, 1994). The ash 

retrieval is based upon a radiative transfer 

model that allows the estimation of the mass 

and size of particles in the volcanic cloud. This 

model assumes that the particles are spherical, 

the particle size distribution within a pixel is 

consistent, and the cloud is continuous (Wen 

and Rose, 1994). User inputs include the 

temperature of the underlying surface and the 

top of the cloud, which can be gathered from the 

satellite image or radiosonde data. 

Atmospheric Corrections. A forward model, 

developed by Watson et al. (2003), was used to 

correct for atmospheric water vapor. In this 

model, an atmospheric profile is run through 

MODTRAN to determine the brightness 

temperature values of the system. The model 

was run with different relative humidities, 

ranging from 0%-100%. Due to the noisiness of 

the data, the values from 8-12 μm and the 

sensor response functions for the respective 

channels were convolved to generate a 

weighted average and, hence a more accurate 

brightness temperature. Using the pressure, dry 

bulb, and wet bulb temperatures of the 

atmospheric profile, the relative humidity (RH). 

This new RH was input into the atmospheric 

profile and run through the forward model again 

to calculate true values for the brightness 

temperatures at 11 and 12 μm. A brightness 

temperature difference (11-12 μm) was 

calculated and subtracted from the 12 μm 

channel of the original data used in the ash 

retrieval. 

Results 

 Volcanic ash retrievals were conducted using 

original BTDs and corrected BTDs for one 

MODIS and three AVHRR images. GMS 

images show ash clouds for both eruptions, 

however, we are unable to quantify the mass at 

this time and the images are hence used for 

locating purposes only. A comparison of the two 

eruptions, indicates that the 18 August eruption 

is much more ash-rich than the 28 August eruption. 

 On 18 August an ash cloud was detected by 

AVHRR, containing 511,301 metric tons of ash, at 

19:48 UTC (Figure 2). Unfortunately, the 

TERRA/MODIS instrument was not operational, so 

no cloud comparisons could be made. The TOMS 

image available for that day, at least 6 hours prior to 

the eruption, shows no evidence of ash. GMS was 

able to track the eruption cloud for the entire day 

following the eruption. Figure 3 shows the infrared 

image taken approximately 10 minutes prior to the 

AVHRR image. 

Figure 2. 18 August image (19:48), 12 hours after 

the eruption, contains 511300 metric tons of ash 

Figure 3. 18 August GMS infrared image (19:38) 

taken approximately 10 minutes prior to the AVHRR 

image. 

 The ash cloud is also detected on 19 August by 

both MODIS (Figure 4) and AVHRR (Figures 5). 

Both images, though only 6 hours apart, show 

drastically different results: MODIS (01:05 UTC) = 
Session 3 – Page 75 

20,015 metric tons and AVHRR 07:12 UTC) = 

148,939 metric tons. A TOMS Aerosol Index 

(AI) dataset (00:40 UTC) shows a substantial 

ash cloud, collocated with the other two sensor 

clouds (Figure 6). GMS images at near 

coincident times with the MODIS, AVHRR, and 

TOMS images are presented in figures 7-9 

respectively. 

Figure 4. 19 August MODIS ash retrieval 

(01:05), 17 hours after the eruption. At this time 

the cloud contained about 150,000 metric tons 

of ash. 

Figure 5. 19 August AVHRR image (07:12), 23 

hours after eruption, contains approximately 

20000 metric tons of ash. 

Figure 6. 19 August TOMS AI (00:40). Positive 

values indicate the presence of volcanic ash. 

Figure 7. 19 August GMS IR image at 01:38 UTC. 

Figure 8. 19 August GMS IR image at 07:38 UTC. 
Session 3 – Page 76 

Figure 9. 19 August GMS IR image at 00:40 

UTC. 

 The 28 August ash cloud is significantly 

smaller than the 18 August cloud. An AVHRR 

image taken approximately one hour after the 

eruption shows only 211 metric tons of ash 

(Figures 10). Four minutes after the AVHRR 

image, GMS was also able to detect the ash 

cloud (Figure 11). TOMS was unable to detect 

this small injection of ash into the atmosphere 

when the image was taken several hours later. 

Figure 10. 28 August image (20:34), 1 hour 

following eruption, contains 211 metric tons of 

ash. 

Figure 11. 28 August GMS IR image (20:38), within 

four minutes of the AVHRR image. 

Discussion 

 Since Miyakejima is located in a moist, marine 

environment, atmospheric water vapor is a concern 

when attempting to quantify ash. Table 1 compares 

the difference seen in the mass, mean effective 

radius (MER) of the particles, and optical depth of 

the cloud. In all cases, the three variables increased 

as water vapor was removed from the system. Mass 

was the most changed in all four cases, with 

corrected values ranging from 2.5 to almost 29 times 

larger than the original result. In an attempt to better 

understand how the correction works, a plot of 

corrected mass divided by the original mass versus 

the change in brightness temperature (which was 

calculated from the removal of water vapor) was 

created (Figure 12). While the graph indicates a 

high R2

 value (0.9137), it is important to note a few 

points: 1) the highest point represents the large 

difference between the two retrieved masses and 

appears anomalously large, 2) only four images 

detected ash, while typically any sort of convincing 

correlation should contain a larger dataset, and 3) 

two of the brightness temperature differences are 

the same because the images are on the same day. 

Generally, the trend shown is what one would 

expect, the ash cloud mass decreases with time and 

the smaller the brightness temperature difference, 

the smaller the difference between the two masses. 

In order to insure the accuracy of such a correction 

technique, an eruption with a persistent, detectable 

ash cloud should be used. 
Session 3 – Page 77 

Date, Time Mass 

(tons) 

MER (μm) Optical 

Depth 

8/18, 19:48 17954 8.41 0.97 

511301 9.27 1.31 

 

8/19, 01:05 22680 7.27 0.39 

148939 8.84 0.75 

 

8/19, 07:12 8152 6.35 0.43 

20015 6.36 0.49 

 

8/28, 20:34 74 6.65 0.31 

211 6.91 0.34 

Table 1. Comparison of original and 

atmospherically corrected ash retrievals. 

Corrected retrieval results are in italics. 

y = -43.617x - 18.296

R2 = 0.9137

0

5

10

15

20

25

30

-1.2 -1 -0.8 -0.6 -0.4 -0.2 0

Figure 12. Plot of brightness temperature 

difference versus the mass from the corrected 

and original data. 

Conclusions 

 Ash was best detected by and can be 

quantified using infrared sensors. Geostationary 

satellites seem to be the best option for tracking 

ash clouds and therefore for use by VAACs. 

AVHRR and MODIS are both aboard polar 

orbiting satellites, which cover the same area 

earth approximately twice per day. At this time, 

these are the only satellites available in the 

Japan area to use for quantification of mass and 

particle size. GMS will be of use for 

quantification in the future, however, creating a 

retrieval method was out of the scope of this 

study. 

Acknowledgments 

Financial support for this project was received 

from the Michigan Space Grant Consortium 

Graduate Fellowship Program, Sigma Xi Grantsin-aid of Research, and a NASA grant: 

Validation of TOMS Volcanic Aerosol and SO2

Products Using MODIS and AVHRR. GMS data is 

courtesy the Japan Meteorological Satellite Center. 

We would also like to thank the Japan 

Meteorological Agency and the Volcanic Clouds 

Group at Kagoshima for sharing Miyakejima 

information. 

References 

Geshi, N., T. Shimano, T. Chiba, S. Nakada, 

 Caldera collapse during the 2000 eruption of 

 Miyakejima Volcano, Japan, Bull. Volcanol, 

 64, 55-68, 2002. 

Kinoshita, K, C. Kanagaki, N. Iino, M. 

 Koyamada, A. Terada, A. Tupper, Volcanic 

 plumes at Miyakejima observed from satellites 

 and from the ground, Remote Sensing of the 

 Atmosphere, Ocean, Environment, and 

 Space, Hangzhou, China, October, 2002. 

Wen, S. and W. I. Rose. Retrieval of sizes and 

 total masses of particles in volcanic clouds 

 using AVHRR band 4 and 5, J. Geophys. 

 Res., 99, 5421-5431, 1994. 

Watson, I.M., Realmuto, V.J., Rose, W.I., Bluth 

 G.J.S., Forward modeling of volcanic aerosols 

 transmissions at different latitudes; 

 quantifying the effects of varying water vapor 

 on ash detection, Abstract, AGU Meeting, Fall 

 2003. 
P3.11 

Session 3 – Page 79 

PREDICTING REGIONS SUSCEPTIBLE TO HIGH CONCENTRATIONS OF AIRBORNE 

VOLCANIC ASH IN THE NORTH PACIFIC REGION 

Kenneth Papp, Ken Dean, and Jonathan Dehn, Geophysical Institute, University of Alaska, 

Fairbanks, AK, USA 

Airborne ash probability distribution (AAPD) maps have been generated to show the distribution 

of airborne volcanic ash in the North Pacific (NOPAC) region by simulating volcanic eruption 

clouds from 22 of the 100 most historically active volcanoes in the region. The PUFF ashdispersion model was run daily using archived wind field data between 1994–1995 and 1997–

2001 for low and high aircraft flight levels. Subsequent statistics are generated representing the 

distribution of simulated airborne ash at 6 and 24 hr intervals, defining the regions most likely to 

contain airborne ash and the direction and distance a volcanic ash cloud may propagate from a 

given volcano. The AAPD maps suggest eruptions originating from the Kamchatkan Peninsula 

would travel due east into the NOPAC air-traffic routes during summer. During the winter, wind 

directions over the Kamchatkan Peninsula are more variable, often resulting in a bimodal 

airborne ash distribution. In contrast, AAPD maps show that eruptions originating from the 

Aleutians and Alaskan Peninsula are more likely to travel in southeast directions during the 

summer and E-NE during winter. The results indicate that the paths of many NOPAC air traffic 

routes coincide with airborne ash distribution probability maxima. The upper atmospheric region 

most likely to contain airborne ash is located off the eastern coast of the Kamchatkan Peninsula, 

and is generally centered over the heavy air traffic flight corridor of the NOPAC. 
P3.12 

Session 3 – Page 81 

REANALYSIS OF ERUPTION CLOUDS FROM THE NORTH PACIFIC AND 

THEIR IMPACT ON AIRCRAFT ROUTES 

Rorik Peterson, Ken Dean, Jonathan Dehn, Laura Bickmeier, 

and Joanne Groves 

Geophysical Institute, Univ. of Alaska, Fairbanks 

Introduction 

 The Alaska Volcano Observatory has been 

monitoring volcanoes in the North Pacific 

(NOPAC) Region for approximately 15 years 

using satellite data and dispersion models. Over 

this period nearly a hundred plumes and eruption 

clouds have been detected. During this time, 

detection and monitoring capabilities have evolved 

and improved significantly, and the growing data 

archives have been organized and consolidated. 

 The relatively recent 2001 eruption of Mt. 

Cleveland, Alaska, was reanalyzed by AVO's 

University of Alaska, Fairbanks (UAF) site with 

regard to potential aircraft exposure to airborne 

volcanic ash. The combination of satellite data, 

dispersion model forecasts, and flight route data 

provides an insightful perspective on the impact 

the ash cloud had on air traffic in the region. 

Background 

 Analysis of aircraft flight-paths during and 

after the eruption of Mt. Cleveland suggests that 

some aircraft may have flown through the drifting 

ash cloud 18-24 hours after the start of the 

eruption. However, no mechanical problems were 

reported. To assess these potential encounters, we 

have compared the flight paths of the aircraft to 

satellite observations of the ash cloud and to Puff 

dispersion model predictions. Also, we have 

developed a relative ash exposure rating for 

aircraft that may have flown through the ash 

cloud. 

The 19 February eruption of Mt. 

Cleveland produced a volcanic cloud that formed 

an arc over 1,000 km long, and drifted to the NE 

across Alaska (Dean et al., 2004, Dean et al. 

2002). The cloud was detected and its movement 

tracked using data from multiple satellite sensors, 

including GOES, AVHRR and MODIS for 

approximately 50 hours. The translucent cloud 

was detected on the GOES data at half-hour 

intervals after the start of the eruption, 

approximately 1430 UTC. These data were 

processed using the brightness temperature 

difference (BTD) technique (Prata, 1989). The 

altitude of the cloud increased over time from 7.5 

km a few hours after the start of the eruption to 12 

km eight hour later (Dean et al., 2002). 

The Anchorage Volcanic Ash Advisory 

Center (VAAC), working with the Alaska Volcano 

Observatory (AVO), issued alerts (SIGMET) 

warning aircraft of the presence of the cloud and 

its position. The first SIGMET was issued Feb. 19 

at 1847 UTC warning of a “possible eruption at 

Cleveland Volcano”, a short time later an18-hour 

forecast was issued based on dispersion model 

simulations. A portion of the cloud was reported 

at “FL200-FL400” (approximately 20-40 thousand 

feet). Several pilots reported observing the cloud 

and gave height estimates, and others reported ash 

and a sulfur odor in the cockpit (Simpson, et. al, 

2002). 

Method 

 Real-time and archived air traffic control 

data are publicly available from several vendors. 

These data include the latitude, longitude, altitude 

and speed of aircraft with a one-minute time 

resolution. Using archived data obtained from 

Flight Explorer®, we compared air traffic flight 

paths in the North Pacific (NOPAC) Region to 

satellite data and dispersion model simulations for 

the 48 hour period after the start of the eruption. 

For the most part, aircraft avoided the 

general area of the ash cloud during the first 16 

hours (1430 to 0630 the following day), although 

there is a four-hour gap in the air-traffic data from 

0100-0400 on Feb. 20. For the subsequent 18 

hour period, some aircraft flew through a vertical 

plane that included the ash cloud. Figure 1 shows 

the BTD-processed satellite image at 1345 UTC 

superimposed with air-traffic routes from 1315 – 

1415 UTC. Circles indicate the last recorded 

location of each flight during this time period. 

The altitude of aircraft is known and the altitude of 

the ash cloud-top is estimated using cloudatmosphere temperature correlations, pilot reports 
Session 3 – Page 82 

and dispersion models at various times. However, 

the lower extent of the cloud is nearly impossible 

to ascertain. Thus, we are able to predict/estimate 

if a plane flew above the cloud (missing) or near 

the height of the cloud (possibly an encounter) but 

it is impossible to determine if the aircraft 

encountered ash at altitudes lower than the top of 

the cloud. 

 To determine the three-dimensional extent 

of the ash cloud, the Puff volcanic ash dispersion 

model was used to simulate this event using NCEP 

reanalysis windfield data. Puff is a Lagrangian 

model that uses tracer particles, and calculates 

advection, diffusion, and sedimentation rates for 

individual tracer particles using a first-order Euler 

method (http://puff.images.alaska.edu).. Relative 

concentration information is possible and absolute 

concentration may be calculated if the eruptive 

mass rate can be approximated. Simulation results 

of the two-dimensional lateral extent agree with 

the BTD data (compare Figures 1 and 2). 

 A Puff simulation using a 10-minute time 

resolution was performed in order to analyze the 

flight paths of some selected flights nearby the ash 

cloud. A one-hour sequence of forecasts 

superimposed with flight trajectories are shown in 

Figure 3. Comparing flight paths to the 4-

dimensional (space and time) Puff simulations 

indicate that some aircraft flew through regions 

with predictions of elevated ash concentration. 

Estimating the total tephra volume at 1х108

 m3, the 

absolute concentration was calculated for the 

regions through which the planes flew. A total 

potential exposure was then calculated as E = c·t, 

where c is the ash concentration in mg/m3

, and t is 

time in minutes. The potential exposure for all 

flights in the vicinity was calculated during the 48-

hour period following the event, and the ten 

highest exposure values are shown in Figure 4. 

Letters correspond to the flights labeled in Figure 

3. Three flights (A, B, and K) traveled through the 

northern tip of the simulated cloud between 0800-

1000 UTC on Feb. 20. Six other flights traveled 

though the center of the predicted cloud between 

1330-1530 UTC of the same day, and one flight 

(C) through the southern tip. 

 Dispersion model forecasts also contain 

particle size and distribution information in 

addition to concentration. More complicated 

exposure calculations involving particle size are 

possible. Although there is limited data 

concerning the effect of different particle sizes on 

jet engines, it is reasonable to assume that the 

smallest fraction, that less than 1 micron, would 

have negligible effect on jet engines. Since 

particle fall velocity is proportional to the cube of 

the particle size (in laminar flow), only the 

smallest fraction remains airborne at longer times. 

However, until more precise information about the 

actual particle-size cutoff for damage is available, 

a conservative estimate that does not depend on 

size is presented. 

Discussion 

 The meaning of these results deserves 

careful scrutiny for three major reasons: (1) model 

simulations are extremely difficult to validate; (2) 

absolute ash concentration is based on some 

potentially tenuous assumptions about effusive 

rate and initial ash column dynamics; and (3) the 

concentration of volcanic ash that damages jet 

engines is unknown. However, further 

investigation of calculating potential exposure has 

several merits. First, low-level exposure to 

volcanic ash may be difficult to detect during 

routine aircraft maintenance. If aircraft that 

potentially encountered ash are identified, a more 

thorough inspection can be performed, possibly 

mitigating a future dangerous situation. Second, 

potential exposure can be calculated ahead of time 

for an existing air route during an on-going 

volcanic event as a tool to determine the degree of 

avoidance and caution necessary. This may be 

particularly beneficial in later stages when ash 

concentrations have dropped to levels that are 

difficult or impossible to detect with remote 

sensing techniques. 

The exposure rating project is in its early 

stage of development and our initial analysis of 

these data is presented here. AVO and UAF will 

be refining the modeling techniques, and will 

attempt to validate the exposure rating system 

based on reports of aircraft-ash encounters in order 

to further assess possible uses of this information. 

References 

Dean, K. G., J. Dehn, K. R. Papp, S. Smith, P. 

Izbekov, R. Peterson, C. Kearney, and A. 

Steffke, 2004. Integrated satellite observations 

of the 2001 eruption of Mt. Cleveland, Alaska, 

Jour. Volc. Geophy. Res., 135, 

doi10.1016/j.jvolgeores.2003.12.013 
Session 3 – Page 83 

Dean, K.G., Dehn, J., McNutt, S., Neal, C., 

Moore, R. Schneider, D. 2002. Satellite 

Imagery Proves Essential for Monitoring 

Erupting Aleutian Volcano. EOS Trans. 

Am. Geophys. Union, 83, 241, 246-247. 

Prata, A. J., 1989. Infrared radiative transfer 

calculations for volcanic ash clouds. Geophys. 

Res. Lett., 16, 1293-1296. 

Simpson, J. J., Hufford, G. L., Pieri, D., 

Servranckx, R., Berg, J. S., Bauer, C., 

2002. The February 2001 Eruption of 

Mount Cleveland, Alaska: Case Study of 

an Aviation Hazard. Am. Met. Soc.V. 17, 

691–704. 
Session 3 – Page 84 

Figure 1 – Composite GOES brightness temperature difference (BTD) image at 1345 

UTC on February 20, 2001 overlaid with all flight routes at 1345 ±30 minutes. The last 

recorded position of each flight is shown with a filled circle. Most all flights are entering 

or leaving Anchorage Int'l Airport. The ash cloud as detected using BTD is shown just 

slightly off of the west coast. 
Session 3 – Page 85 

Figure 2 – Puff dispersion model forecast for 1345 UTC on February 20, 2001 overlaid 

with all flight routes at 1345 ±30 minutes. The last recorded position of each flight is 

shown with a filled circle. Ash forecasts are color-coded by height and correspond with 

the color-coding of the flight routes.
Session 3 – Page 86 

Figure 3 – One hour time-series of Puff dispersion model forecasts superimposed with 

selected flight routes. Ash forecasts are color-coded by height and correspond with the 

color-coding of the flight routes. Potential ash exposure calculations recorded the highest 

values for the flights shown.
Session 3 – Page 87 

Figure 4 – Potential ash exposure [mg·min/m3] for the 10 flights with highest values 

calculated during the 48 hours following the eruption. Letters correspond to flight 

trajectories shown on Figure 3. 
P3.13 

Session 3 – Page 89 

QUANTITATIVE SULPHUR DIOXIDE RETRIEVALS FROM AIRS, MODIS AND HIRS 

Fred Prata, CSIRO Atmospheric Research, Aspendale, Australia 

Cirilo Bernardo, CSIRO Atmospheric Research, Aspendale, Australia 

A new suite of algorithms is proposed for retrieving upper troposphere/lower stratosphere 

sulphur dioxide from the infrared channels of the AIRS, MODIS and HIRS satellite instruments. 

The retrieval schemes are tailored to the strengths of each instrument, but all utilise the same 

principle of detecting the strength of absorption by the anti-symmetric stretch of the SO2

molecule centred around 1360 cm-1 (7.34 μm). The AIRS instrument covers this region of the 

infrared spectrum with more than 130 channels and is capable of accurate total column amount 

retrievals with a spatial scale of ~15x15 km2. We also explore the possibility of using microwindows and the 8.6 μm and 4.0 μm regions to infer SO2 height information. The MODIS 

instrument provides a broadband measure of the 7.34 μm SO2 absorption feature, but offers 

unprecedented ~1x1 km2

 spatial resolution and up to 4 measurements per day from two satellites. 

The retrievals are less accurate than those from AIRS. The HIRS family of instruments also 

provide broadband measurements and are of lower spatial resolution (~18 x18 km2

 at nadir) than 

MODIS, but these data span nearly 25 years and are complemented by simultaneous 

measurements of atmospheric temperature, moisture, clouds, radiative parameters and ozone. 

Consequently these data are of great value for studies of the effects of volcanic emissions on 

climate and on the chemical balance of the atmosphere. These new infrared measurements of 

SO2 are compared and contrasted to established measurements from TOMS and GOME. 
P3.14 

Session 3 – Page 91 

Sakura – AN AIRBORNE INFRARED IMAGING CAMERA FOR THE DETECTION OF 

VOLCANIC ASH AND SULPHUR DIOXIDE GAS 

Fred Prata, CSIRO Atmospheric Research, Aspendale, Australia 

Since the early 1990’s CSIRO Atmospheric Research have been investigating the use of infrared 

radiometers for the detection and discrimination of volcanic ash from airborne platforms. The 

intention has been to develop a forward looking infrared camera system that could be deployed 

on commercial jet aircraft. Simulations studies and airborne trials at Sakurajima volcano in 

Japan suggest that infrared radiometry can be used to detect volcanic ash. More recent groundbased trials of an uncooled imaging infrared camera have indicated that sulphur dioxide gas can 

also be detected and the system is now being improved to provide an indication of other 

atmospheric hazards, such as clear-air turbulence, low level wind shear, severe weather and 

desert dust outbreaks. We describe the basic operation of the proposed infrared airborne camera 

(“Sakura”) and demonstrate the overall system performance, “look and feel” and suggest likely 

operating modes. Results from the airborne trials in Japan will be presented and the operation of 

the technology from the ground, from an airborne platform and from a satellite platform will be 

compared and contrasted. Testing of an uncooled infrared imaging camera on board a 

commercial jet aircraft remains a major goal of this project. 
P3.15 

Session 3 – Page 93 

TESTING REAL-TIME REMOTE SENSING FOR MONITORING VOLCANIC ACTIVITY 

IN CENTRAL AMERICA 

Armando Saballos, INETER, Managua, Nicaragua 

Peter Webley and Martin Wooster, Department of Geography, King’s College, London, UK 

We describe the implementation and results of a project to design, install and operate a 

remote sensing-based monitoring system for Central American volcanoes, locally based in 

Managua, Nicaragua but capable of monitoring all of Central America. The system is based 

on AVHRR data capture, and up to eight satellite passes a day are received and processed 

automatically to provide information on volcanic hotspots, and in future ash clouds, with 

minimal human intervention. The project aims to assess whether this type of technology is 

able to significantly improve the capability to locally monitor volcanoes in regions such as 

Central America. Validation is being conduced against other remote sensing and geophysical 

datasets, and a social science component is assessing the onward dissemination of the data 

and its use in hazard assessment. 
P3.16 

Session 3 – Page 95 

ADVANCES IN ULTRAVIOLET DETECTION OF VOLCANIC ERUPTION CLOUDS

Stephen J. Schaefer, Joint Center for Earth Systems Technology UMBC, Baltimore MD, USA 

Arlin J. Krueger, Joint Center for Earth Systems Technology UMBC, Baltimore MD, USA 

Simon A. Carn, Joint Center for Earth Systems Technology UMBC, Baltimore MD, USA 

Sulfur dioxide is the most readily quantified material in volcanic eruption clouds due to low 

background amounts in the atmosphere and strong absorption bands in near ultraviolet 

wavelengths, which are sampled by polar orbiting Total Ozone Mapping Spectrometers (TOMS). 

The new hyperspectral Ozone Monitoring Instrument (OMI) has an increased sensitivity and a 

smaller pixel size (13 x 25 km) than the Nimbus 7 TOMS (50 x 50 km) or the current Earth 

Probe TOMS (39 x 39 km). The OMI will have a greater than 102 improvement in detection 

limit of SO2 in eruption clouds relative to the Nimbus 7 TOMS. Pre-eruptive, passive degassing 

of SO2 on the order of 102 – 103 tons/day should be detectable by OMI and will aid in eruption 

forecasting. Characterization of aerosol particles by type (e.g. ash, sulfate or ice) and size is 

expected utilizing the OMI data and will further refine the risk posed to aircraft by different 

clouds. Current IR instruments have high spatial resolution but may fail to detect volcanic 

clouds at low altitudes or above high clouds due to water vapor interference or poor thermal 

contrast. The UV instruments allow for an unambiguous detection of all volcanic clouds, which 

produces a very low false alarm rate. OMI is on the Aura platform to be launched in June 2004. 

The data are expected to be processed orbit-by-orbit in near real-time for use in volcanic hazard 

detection. 
P3.17 

Session 3 – Page 97 

REAL-TIME MONITORING OF THE VOLCANIC ASH FALLOUT WILL IMPROVE 

AIRPORT SAFETY 

Simona Scollo, INGV, Catania, Italy 

Mauro Coltelli, INGV, Catania, Italy 

Marco Folegani, Nubila, Bologna, Italy 

Stefano Natali, Nubila, Bologna, Italy 

Franco Prodi, ISAC, Bologna, Italy 

PLUDIX instrument was tested to measure terminal settling velocity of volcanic particles 

during the pyroclastic fallout of 2002 Etna’s eruption. The instrument is a new generation 

radar rain-gauge disdrometer, based on the Doppler shift induced by falling particles on the 

transmitted electromagnetic signal, usually used to investigate the space and the time 

variability of rainfall, together the total mass of rain accumulated in the ground. The 

measuring campaign was performed on 18 and 19 December, when explosive activity of Mt. 

Etna produced a long-lived volcanic plumes high 4000 m a.s.l. During the experiment 

PLUDIX instrument detected coherently volcanic ash fallout. Data processing permitted to 

estimated their fall-velocities, using a simple Doppler shift formula. Measured fall velocities 

have been compared with that obtained from Wilson and Huang experiment for particles with 

density, dimension and shape similar to Etna’s ashes. Both data sets are fully comparable 

demonstrating that PLUDIX is not only able to detect volcanic ashes but also to characterize 

in real-time their falling velocities and then the sedimentation rate during the ash fallout. In 

the next step PLUDIX detection method will be modified reducing the maximum detectable 

Doppler shift to improve spectral resolution. Moreover a conversion algorithm to estimate in 

real time the grain size distribution of ash will be implemented. This category of instruments 

could be very useful for real-time monitoring of the volcanic ash fall rate in the airports close 

to the active volcanoes in which operations are often disrupted by explosive eruptions like at 

Catania International Airport during the 2001 and 2002 Etna’s eruptions. 
P3.18 

Session 3 – Page 99 

DEVELOPMENT OF VOLCANIC ASH IMAGE PRODUCTS 

USING MODIS MULTI-SPECTRAL DATA 

George Stephens, NOAA/NESDIS Office of Satellite Data Processing and Distribution, Camp Springs MD 

Gary P. Ellrod, NOAA/NESDIS Office of Research and Applications, Camp Springs, MD 

Jung-Sun Im, IM Systems Group, Inc, Camp Springs, MD

1. INTRODUCTION

 The Moderate Resolution Imaging Spectroradiometer 

(MODIS) on National Aeronautics and Space 

Administration’s (NASA) Aqua and Terra polar-orbiting 

spacecraft provides a total of thirty-six spectral bands: 

twenty 1 km resolution Infrared (IR) bands, and sixteen 

higher resolution (250-500m) visible and near-IR bands 

available for daytime applications. Based on studies with 

data from aircraft or other satellite sensors, several of the 

spectral bands available from MODIS have been shown to 

be useful for the detection of airborne volcanic ash clouds 

that pose hazards to aircraft (Miller and Casadevall 2000). 

For example, the brightness temperature difference (BTD) 

of MODIS Band 31 (11 m) and Band 32 (12 m) is able 

to distinguish silicate volcanic ash from meteorological 

clouds (Prata 1989) due to differential absorption. Another 

longwave IR channel (Band 29 - 8.6 m) exhibits strong 

absorption in the presence of volcanic ash as well as sulfur 

dioxide (SO2) gas emitted by volcanoes (Realmuto et al 

1997). 

 Due to some degradation in the volcanic ash detection 

capability of the Geostationary Operational Environmental 

Satellite (GOES) Imager series beginning with GOES-12 

(2002) through GOES-Q (late 2008 launch), there is a need 

for polar orbiting satellite image products to augment 

GOES in support of the operational aviation volcanic ash 

warning system. The reduced capability of GOES is due to 

the temporary removal of a 12 m IR band that has a 

proven capability for volcanic ash detection (Prata 1989; 

Schneider and Rose 1994). The global aviation warning 

system consists of Volcanic Ash Advisory Centers 

(VAACs) established in 1997 by the World Meteorological 

Organization to provide timely alerts of active volcanic 

hazards and predictions of ash cloud locations to 

Meteorological Watch Offices (MWOs) (Miller and 

Casadevall 2000). Each VAAC has multi-spectral satellite 

data and derived products at its disposal to help detect and 

monitor airborne ash clouds. 

 Work has begun within NOAA/NESDIS to develop 

prototype volcanic ash image products from MODIS to 

support the VAACs, as well as to prepare for advanced 

satellite systems such as the National Polar Orbiting 

Environmental Satellite System (NPOESS) scheduled for a 

prototype launch in 2006, and the GOES Advanced 

Baseline Imager (2012) that will have multi-spectral 

capabilities and resolutions similar to the MODIS. 

2. DATA ANALYSIS 

 Initial analysis of MODIS data has been completed for 

two volcanic eruptions: (1) Cleveland volcano in the 

Aleutian Islands on 19-20 February 2001, and (2) 

Popocatepetl volcano near Mexico City on 19-20 

December 2000. Two data sets were analyzed for each of 

the first two cases (one daytime, one nighttime) using Mancomputer Interactive Data Access System (McIDAS) image 

processing software on PC workstations. The emphasis in 

this work was to develop an optimum IR volcanic ash 

product that could be used twenty-four hours a day, 

regardless of location. However, visible and near-IR bands 

were also evaluated for daytime applications. 

 Various combinations of MODIS IR bands have been 

evaluated. Some initial tests involved producing multispectral ash products used operationally at VAACs such as 

the Two-Band Split Window (TBSW) based on the BTD of 

Bands 32 (12.0 m) and 31 (11 m) described earlier in 

this paper, the Three-band Volcanic Ash Product (TVAP) 

that is based on the TBSW plus Band 22 (3.9 m) (Ellrod 

et al 2002) and a four-channel algorithm (Mosher 2000) 

that also incorporates visible channel information. Other 

combinations were evaluated that utilized Band 30 (9.7 

m), Band 29 (8.6 m), Band 28 (7.3 m), and Band 25 

(4.5 m). 

 The best results for ash cloud discrimination were 

obtained from a three-channel combination of Band 32 

(12.0 m), Band 31 (11.0 m) and Band 29 (8.6 m) 

(hereafter referred to as the Longwave Volcanic Ash 

Product (LVAP)). The most useful shortwave IR channel 

was determined to be Band 25 (4.5 m), which supports 

the results of Hillger and Clark (2002). An advantage of 

Band 25 is that it exhibits considerably less solar 

reflectance than the other shortwave bands, which provides 

more consistent results for both day and night. By 

examining scatter plots of the BTD’s for each of the 

channels, appropriate BTD ranges were empirically 

selected to highlight the likely ash cloud, and minimize the 

meteorological clouds and surface features. 

3. CASES ANALYZED 

3.1 Popocatepetl, 18-20 December 2000 

 On the evening of 18 December 2000, Popocatepetl 

Volcano near Mexico City began an eruption of ash that 

was not explosive, but persisted until the afternoon of the 

20th. It was considered to be the largest eruption of the 
Session 3 – Page 100 

volcano in 75 years. Ash spewed southward from the 

volcano across southern Mexico, reaching the Pacific coast 

on the south, and the Gulf of Mexico on the east after 

Midnight, 20 December 2000. Maximum height of the ash 

was estimated to be about 10.6 km (35,000 ft) (Washington 

VAAC advisory). 

 MODIS observed the ash clouds over southern Mexico 

at 0505 UTC on 20 December 2000. The three-band 

LVAP (Figure 1) provided depiction of the ash cloud 

extent that was in good agreement with concurrent GOES 

imagery, shown in an analysis by the Washington VAAC 

(Figure 2). Comparison with the TBSW image in Figure 1 

indicates that the addition of Band 29 has resulted in a 

slightly larger area of ash compared with the TBSW alone. 

The LVAP detects more of the thin ash over southern 

Mexico, but may also be observing some surface features, 

possibly due to the presence of underlying silicate soils.

 Scatter plots of Band 32 - 31 and Bands 32 - 29 versus 

Band 31 IR temperature (Figure 3) reveal that the TBSW 

alone provides the best discrimination, but Band 32 - 29 

contains some additional information on the presence of 

ash. 

3.2 Cleveland, 19 February 2001 

 On the afternoon of 19 February 2001, Cleveland 

Volcano in the Aleutian Islands of Alaska erupted, sending 

ash as high as 9.1 km (30,000 ft) (Alaska Volcano 

Observatory (AVO) Web site). The ash cloud bifurcated as 

it drifted eastward, with the highest portion of the cloud 

stretching northward across the Bering Sea, and the portion 

below about 6.1 km moving southeast into the Gulf of 

Alaska. 

 A MODIS LVAP image was produced at 2310 UTC, 19 

February 2001 (A - Figure 4). The majority of the ash 

cloud is shown being elongated north and northwest of the 

Aleutian chain, with a thinner component to the southeast. 

Comparison with a simple TBSW product (B) indicates 

that the addition of Band 29 data adds significant value to 

the analysis by detecting the thinner ash to the east and 

southeast of the main ash cloud. The ash cloud coverage 

from MODIS compares favorably with the 2315 UTC 

analysis based on 30-minute interval GOES TBSW images 

from the Alaska Volcano Observatory (Figure 5). 

 A scatter plot of the BTD’s for Bands 32 – 31 and 

Bands 32 – 29 versus Band 31 IR temperature (Figure 6) 

shows that both allow good discrimination of ash from 

meteorological water and ice clouds, but the latter provides 

the best result in this case.

4. ADDITIONAL EXPERIMENTS 

 Tests were conducted of techniques for detection of 

sulfur dioxide (SO2). The SO2 test involved the use of a 

multi-channel, stepwise threshold test developed by Crisp 

(1995). The Crisp technique employs Bands 27, 28, 31, 

and 36. The tests were negative for all cases, presumably 

because the technique is only able to detect SO2 at altitudes 

between 6 km and 25 km. The eruption cases studied in 

this paper were relatively weak eruptions that did not emit 

ash and SO2 into the Stratosphere. 

 Experiments with Red-Green-Blue (RGB) color 

composite techniques were also conducted to produce 

images that provide optimum colorized depiction of the ash 

cloud, meteorological cloud types, and surface conditions 

to aid in interpretation of the event. One result of the tests 

is a daytime image product that combines information from 

the three-band IR volcanic ash image with visible Band 1 

(0.6 m) and near-Infrared Band 6 (1.6 m) data. The 

latter two channels help distinguish ice versus water clouds 

due to the lower solar reflectance of ice cloud particles and 

snow cover in Band 6 than in Band 1. An example of this 

RGB image for the Cleveland eruption derived using the 

McIDAS software is shown in Figure 7. Volcanic ash 

appears red, water droplet clouds as a greenish hue, and ice 

clouds and snow as blue. 

5. ANALYSIS OF REAL-TIME MODIS DATA 

 Procedures were developed to analyze near real-time 

“Level 1b” MODIS data downloaded from the NASA 

DAAC via a file transfer protocol (ftp) site at Federal 

Building 4 in Suitland, Maryland. Once the data were 

downloaded, a program written in McIDAS was run to 

generate LVAP images in an effort to evaluate the MODIS 

data for “null” events in which no known volcanic activity 

was occurring. In these images it was discovered that there 

are some regions over land areas where “false alarms” for 

ash clouds were observed. These are believed to be due to 

the radiation characteristics of sandy soils consisting of 

silicate minerals. In order to avoid this, a sequential test 

can be used, requiring that a Band 32 – Band 31 threshold 

be satisfied before information from the Band 32 – Band 29 

can be incorporated into the final image product. 

6. DATA PROCESSING AND DISTRIBUTION 

NESDIS’ Satellite Services Division is implementing the 

product operationally for use in issuance of Volcanic Ash 

Advisories by the Washington Volcanic Ash Advisory 

Center (W-VAAC). Level 1b MODIS data are pulled from 

NOAA computers located at the NASA Goddard Space 

Flight Center for use in various products, including the Ash 

Product. LVAP and RGB composites are processed over 

geographic areas of responsibility of the W-VAAC and the 

Alaska VAAC in Anchorage AK, and will be made 

available on a Geospatial Information System compatible 

web site. (Figure 8.) 

7. RECENT EXAMPLES FROM THE W-VAAC 

A continuing series of eruptions at Tungurahua Volcano in 

Ecuador in August, 2003 provided several opportunities to 

validate the MODIS Volcanic Ash Product, as 

implemented in the W-VAAC. A comparison, below, of 

MODIS (Figure 9.), Advanced Very High Resolution 

Radiometer (AVHRR) (Figure 10.) and Geostationary 
Session 3 – Page 101 

Environmental Operational Satellite (GOES) Imager 

derived graphical analysis (Figure 11.) demonstrates 

excellent agreement, with the MODIS product providing 

enhanced detection of thin ash to the west of the volcano. 

8. SUMMARY AND CONCLUSIONS 

 Experimental volcanic ash products have been derived 

and evaluated using MODIS data from the Terra spacecraft 

for two volcanic eruptions: Popocatepetl, Mexico (20 

December 2000) and Cleveland, Alaska (19 February 

2001). The best results, based on subjective comparisons 

with frequent interval GOES imagery, were obtained from 

a tri-spectral combination of Bands 29 (8.6 m), 31 (11.0 

m) and 32 (12.0 m). Volcanic ash detection using a 

simple two-band split window (TBSW) derived from Band 

32 - Band 31 was only slightly less effective. Optimum 

color composite images have been developed to provide 

information on ash cloud location, as well as cloud phase 

and surface characteristics, to aid in interpretation both day 

and night. Additional work will attempt to reduce false 

alarms from silicate soils in Band 29, and develop 

procedures for real-time production of operational products 

for use in VAACs. 

9. ACKNOWLEDGMENTS 

 The authors would like to thank Dr. Donald Hillger of 

the NESDIS Regional and Mesoscale Meteorology Team, 

Ft. Collins, Colorado, and Drs. Matthew Watson and 

William Rose, Michigan Technological University, 

Houghton, Michigan, for providing the MODIS data 

described in this paper. 

10. REFERENCES 

Crisp, J., 1995: Volcanic SO2 Alert. EOS IDS 

Volcanology Team Data Product Document #3288, Jet 

Propulsion Laboratory, California Inst. of Technology, 13 

pp. 

Ellrod, G. P., B. Connell and D. W. Hillger, 2002: 

Improved detection of airborne volcanic ash using multispectral infrared satellite data. J. Geophys. Res., In review. 

Hillger, D. W., and J. D. Clark, 2002: Principal component 

image analysis of MODIS for volcanic ash, Part-1: Most 

important bands and implications for future GOES Imagers. 

J. Appl. Meteor., In press. 

Miller, T. P., and T. J. Casadevall, 2000: Volcanic ash 

hazards to aviation. In: Encyclopedia of Volcanoes, H. 

Sigurdsson, Ed., Academic Press, San Diego, California, 

pp 915-930. 

Mosher, F. R., 2000: Four channel volcanic ash detection 

algorithm. Preprint Volume, 10th Conf. on Satellite 

Meteor. and Oceanography, 9-14 January 2000, Long 

Beach, California, 457-460. 

Prata, A. J., Observations of volcanic ash clouds in the 10-

12 micrometer window using AVHRR/2 data. Int. J. 

Remote Sens., 10, 751-761, 1989.

Realmuto, V. J., A. J. Sutton, and T. Elias, 1997: 

Multispectral imaging of sulfur dioxide plumes from the 

East Rift Zone of Kilauea volcano, Hawaii. J. Geophys. 

Res., 102, 15057-15072.

Schneider, D. J., and Rose, W. I., Observations of the 

1989-1990 Redoubt volcano eruption clouds using 

AVHRR satellite imagery. In: Volcanic ash and aviation 

safety: Proceedings of the First International Symposium 

on Volcanic Ash and Aviation Safety. U. S. Geological 

Survey Bulletin 2047, 405-418, 1994.

Wright, R., L. Flynn, H. Garbeil, A. Harris, and E. Pilger: 

2002: Automated volcanic eruption detection using 

MODIS. Remote Sensing of Environment, 82, 135-155. 

Figure 1. Comparison of MODIS LVAP (A), and 

TBSW (B) images at 0505 UTC, 20 December 2000. 

Figure 2. VAAC analysis near the time of MODIS 

image in Figure 1, based on GOES imagery.
Session 3 – Page 102 

Figure 3. Scatter plots showing BTDs for Bands 

32-31 (top) and Bands 32 – 29 (bottom) at 0505 

UTC, 20 December 2000. 

Figure 4. Comparison of MODIS LVAP (A) 

With TBSW (B) at 2310 UTC, 19 February

2001. 

Figure 5. Spreading of ash cloud from Cleveland 

Eruption on 19 February 2001 based on GOES 

TBSW animation. Time closest to MODIS data is 

outlined. (Alaska Volcano Observatory) 

Figure 6. Scatter plots of Bands 32 – 31 (top) and Bands 

32 – 29 (lower) versus Band 31 temperature for Cleveland 

case at 2310 UTC, 19 February 2001. 
Session 3 – Page 103 

Figure 7. Red-Green-Blue composite showing ash 

coverage from MODIS LVAP as red, Band 6 (1.6 m) as 

green, and Band 1 (0.6 m visible) as blue. 

Figure 8. Geospatial web site display of LVAP RGB 

composite imagery covering Central American region, 

delineated above. 

Figure 9. MODIS AQUA LVAP RGB composite Aug. 31, 

2003 1910 UTC. 

Figure 10. AVHRR “split window”, ch.4 – ch.5 Aug. 31, 

2003 

1926 UTC 

Figure 11. W-VAAC graphical analysis from GOES 

imagery Aug. 31, 2003 1445 UTC 

Figure 12. LVAP detected an eruption of Sheveluch 

Volcano on Siberia’s Kamchatka Pen-insula, May 10, 

2004 
P3.19 

Session 3 – Page 105 

VOLCANIC ASH DISPERSION MODELING RESEARCH 

AT NOAA AIR RESOURCES LABORATORY

Barbara J.B. Stunder1

 and Jerome L. Heffter 

NOAA Air Resources Laboratory, Silver Spring, MD, USA 

 

1

Corresponding author: Barbara.Stunder@noaa.gov, NOAA Air Resources Laboratory (R/ARL), 1315 East-West 

Highway, Silver Spring, MD, 20910, USA 

ABSTRACT 

The National Oceanic and Atmospheric 

Administration (NOAA) Air Resources 

Laboratory (ARL) is conducting research, using 

the HYSPLIT model, to improve volcanic ash 

forecast guidance. In one project, preliminary 

results suggest an archive of trajectory forecasts 

and dispersion forecast patterns from hypothetical 

eruptions and corresponding (hypothetical) 

analysis dispersion patterns can be used to predict 

the reliability of subsequent forecasts. In another 

project, ensemble meteorology is used to create a 

prototype probabilistic forecast product. More 

research is needed to determine the applicability of 

ensemble dispersion products.

INTRODUCTION 

The Hybrid-Single Particle Lagrangian 

Integrated Trajectories (HYSPLIT) model was 

developed at the NOAA Air Resources Laboratory 

beginning in the early 1980s (Draxler and Taylor, 

1982). Draxler and Hess (1998) describe the last 

major upgrade and compare HYSPLIT-calculated 

concentrations to measurements from field 

experiments, calculated Cs-137 deposition to that 

from the 1986 Chernobyl accident, and calculated 

volcanic ash to satellite imagery for the Rabaul, 

September, 1994 eruption. Results from recent 

model upgrades (see 

http://www.arl.noaa.gov/ready/hynew.html) are 

compared against a database of tracer 

measurements from field experiments, the "Data 

Archive of Tracer Experiments and Meteorology" 

(DATEM - see http://www.arl.noaa.gov/datem/). 

HYSPLIT was implemented at NCEP in 1998 (see 

http://www.nws.noaa.gov/om/tpb/458.htm) for 

radiological applications. The planned NOAA 

National Centers for Environmental Prediction 

(NCEP) installation of ARL’s current version of 

HYSPLIT will include the ability to run HYSPLIT 

for volcanic ash transport and dispersion 

forecasting and produce output in the same format 

as VAFTAD. 

Evaluation of volcanic ash dispersion 

forecasts includes two main components: the 

dispersion model and the meteorological forecast. 

To evaluate the dispersion model, model 

calculations using analysis meteorology are 

compared to volcanic ash observations, typically 

satellite analyses. To evaluate the meteorological 

forecast, the model calculations using forecast and 

analysis meteorology are compared. Current 

research at ARL is focused on the meteorological 

component, to provide more useful volcanic ash 

dispersion guidance products. Two ongoing 

projects will be described: one to assess the 

reliability of a forecast, the other to assess the 

possible use of ensemble dispersion forecasts. 

FORECAST PATTERN RELIABILITY 

The reliability of a forecast pattern is 

based on past patterns with similar meteorological 

situations. We hypothesize that forecasts are more 

reliable in some situations and less reliable in 

other situations. Forecasters aware of this 

differentiation may be able to better interpret 

forecast model output and thereby assign a degree 

of reliability to the forecast. Seven volcanoes 

were chosen for this study, in or near areas of 

responsibility of the Volcanic Ash Advisory 

Centers (VAACs) located at Washington and 

Anchorage. 

 Area Volcano

1. Alaska Augustine 

2. N. Atlantic Hekla 

3. Mexico Popocatepetl 

4. NW United States Rainier 

5. Kamchatka Sheveluch 
Session 3 – Page 106 

6. Caribbean Soufrierre Hills 

7. South America Tungurahua 

A daily archived database is being created 

for hypothetical eruptions of each volcano listed 

above. The data include: a forecast trajectory, a 

forecast pattern, and an "offset" forecast pattern. 

The offset forecast pattern is the mean of the 8 

forecast patterns using meteorology offset by one 

degree of latitude and longitude surrounding the 

volcano (Draxler, 2003), and the forecast pattern 

from the volcano without offset meteorology. All 

forecasts are run out to +18 hours. For reference, 

an analysis pattern is run using analysis 

meteorology for the days corresponding to the 

forecasts. In summary, the archived database 

contains, for each volcano, on each day, a 

trajectory, a forecast pattern, an offset forecast 

pattern, and an analysis pattern. 

When corresponding forecast and analysis patterns 

are compared (Fig. 1), a forecast region that 

overlaps an analysis region is called a "hit", a 

forecast region that extends beyond an analysis 

region is called "excess", and the region of the 

analysis that was not forecast is called a "miss". 

For the aviation community, some degree of an 

excess region (false alarms) may be acceptable, 

but even a small degree of a miss region may be 

dangerous to aircraft safety 

.

 excess 

 

 

Figure. 1. Illustration of terminology with a 

forecast and analysis pattern: hit, miss, and 

excess. 

The meteorological conditions for each 

forecast are categorized by the trajectory quadrant, 

trajectory distance, and the ratio of the offset 

forecast pattern area to the forecast pattern area, 

the "offset excess ratio" (Fig.2). 

Figure 2: Offset excess ratio is the ratio of the 

forecast pattern area (solid oval) to offset 

forecast pattern area (irregular shape). 

When an operational forecast is run, the 

database is searched for cases with meteorological 

conditions (trajectory quadrant and distance, and 

offset excess ratio) closely matching those for the 

forecast. A FOPARE (FOrecast PAattern 

REliability) chart that displays the percent of 

excess, hits, and misses for the matching cases, 

and their mean, can be created (Fig. 3). 

Preliminary results suggest that FOPARE charts 

with a small proportion of misses (<30%, 100% - 

70%) and a small proportion of excesses (<30%) 

indicate the forecast is "reliable". When the misses 

are greater than 30% the forecast should be used 

with caution, since a significant percent of the ash 

pattern may extend beyond the forecast pattern. 

The above thresholds for misses and excesses have 

yet to be verified for operational use. 

Excess

Miss

Hit

Forecast

Analysis
Session 3 – Page 107 

Figure 3. Example FOPARE chart. 

ENSEMBLE DISPERSION FORECASTS 

Uncertainties with volcanic ash dispersion 

forecasts have not been quantified. Servranckx 

and Chen (2004) describe some of the uncertainty 

as arising from uncertainties in the source term, 

meteorology, and transport and dispersion 

parameterizations. Current models, such as 

VAFTAD, and the planned NCEP implementation 

of HYSPLIT, use pre-determined ash particle 

specifications and vertical distributions, a given 3-

dimensional meteorology dataset, certain transport 

and dispersion algorithms, and for real-time 

forecasting, an estimate of the eruption column 

height and eruption duration. A collection of 

dispersion forecasts using a range of realistic 

inputs and/or model algorithms/parameterizations, 

can be called an "ensemble" to show the range of 

forecast possibilities and the corresponding 

probabilistic forecast. 

As an example, if the eruption column 

height is determined to be in a range between 

20,000 ft and 25,000 ft, the model can be run for 

both heights, i.e. a 2-member ensemble. If the 

results are similar, then knowing the exact height 

is not important. If the results are different, 

perhaps because wind speeds vary significantly 

from 20,000 ft and 25,000 ft, the forecaster would 

need to use both model outputs to produce a 

forecast. The combined forecast product would 

then account for the uncertainty in the eruption 

column height. 

Another dispersion ensemble can be 

created from the NCEP ensemble global 

meteorology forecast, which is based on an 

estimate of the uncertainty in the meteorological 

analyses (Szunyogh and Toth, 2002). For each of 

the 10 NCEP ensemble members, the model is run 

with a different analysis, which leads to different 

meteorological forecasts. 

To illustrate an ensemble dispersion 

forecast, based on the NCEP ensemble 

meteorology, we chose a hypothetical 40,000 ft 

(about 12,200 m) eruption of Pavlof, Alaska, at 00 

UTC 21 May 2004. Figure 4 shows the forecast 

pattern 18 hours after the eruption, for the layer 

from the surface to about FL550. The 

concentrations shown (units per cubic meter), 

spanning four orders of magnitude, are with 

respect to the mass (one unit) in the initial eruption 

column. In an operational setting, the mass of an 

eruption is not known so one unit is typically 

assumed. 

Figure 4. HYSPLIT 18-h forecast using operational 

NCEP GFS meteorology for a hypothetical 40,000 ft 

eruption of Pavlof at 00 UTC 21 May 2004. 

To illustrate the differences in the 

meteorology, trajectories were computed using the 

ensemble members’ meteorology beginning at the 
Session 3 – Page 108 

time of the hypothetical eruption (Fig. 5). At 18 

hours downwind from Pavlof, the trajectory 

endpoints span about 400 km in the crosswind and 

alongwind directions. 

The individual dispersion forecast patterns 

based on the ensemble members (not shown) are 

generally similar to that of the operational forecast 

(Fig. 4), but show differences as suggested by the 

ensemble trajectories (Fig. 5). Calculating the 

mean dispersion forecast (Fig. 6) from the 

ensemble member forecasts shows a larger area of 

ash than the operational forecast. 

Figure 5. The ensemble of 18-hour duration 

HYSPLIT trajectories from Pavlof, beginning 

at 00 UTC 21 May 2004. 

Figure 6. Mean dispersion forecast from the 

ensemble member dispersion forecasts. 

Statistics other than the mean may also be 

computed from the ensemble member dispersion 

forecasts (Draxler, 2003). For example, the 

probability that the ash concentration exceeds 1.0 

x 10-17 (arbitrarily chosen) is shown in Figure 7. 

The area with probability greater than 0%, as 

expected, is similar to the area with ensemble 

mean concentrations greater than 1.0 x 10-17 (Fig. 

6). The area with probability greater than 25% is a 

small region. We do not have enough data yet to 

determine the usefulness of a product similar to 

this, or how a forecaster would use it. To 

speculate, a forecaster receiving a product such as 

Figure 7 might then develop a forecast that ash is 

likely in the area around the 25% probability area, 

but is possible in the area with non-zero 

probabilities. Forecasts such as this are somewhat 

analogous to current weather forecasts with 

probability of precipitation. 
Session 3 – Page 109 

Figure 7. Forecast probability that ash 

concentrations are greater then 1.0E-17. 

Figure 8 shows the actual, but 

hypothetical, dispersion pattern based on analysis 

meteorology. Comparison to the operational 

forecast (Fig. 4) shows a generally similar pattern, 

but the analysis pattern is slightly farther north, 

within the ensemble mean pattern (Fig. 6). This 

suggests that, for this case, though the forecast was 

good (similar to that with analysis meteorology), 

use of the ensemble dispersion information may 

have provided additional useful information. 

Figure 8. HYSPLIT analysis using analysis GFS 

meteorology corresponding to the forecast in Fig. 4. 

Further research is needed beyond this 

case study in the dispersion application of the 

NCEP ensemble meteorology. More traditional 

use of the NCEP ensembles, such as 500 hPa 

height contours and quantitative precipitation 

forecasts, has focused on the mid- to long-range 

forecasts, i.e. greater than about 3 days. Use for 

short-term forecasts, as done here, needs to be 

assessed. 

SUMMARY 

Dispersion modeling research projects 

using the HYSPLIT model are being conducted at 

NOAA to provide more useful volcanic ash 

forecast guidance. In one project, the goal is to 

provide a qualitative assessment of the reliability 

of a forecast. In another project, the applicability 

of the NCEP ensemble meteorology forecast to 

improve dispersion forecasts is being studied. 

Results of both projects may lead to additional 

information of use to the forecaster. 

REFERENCES 

Draxler, R.R., 2003: Evaluation of an ensemble 

dispersion calculation, J. Applied Meteorology, 

42, 308-317. 

Draxler, R.R. and G.D. Hess, 1998: An Overview 

of the Hysplit_4 Modeling System for 

Trajectories, Dispersion, and Deposition, Aust. 

Met. Mag., 47, 295-308. 

Draxler, R.R. and A.D. Taylor, 1982: Horizontal 

dispersion parameters for long-range transport 

modeling, J. of Applied Meteorology, 21, 367-

372. 

Heffter, J.L., 1996: Volcanic ash model 

verification using a Klyuchevskoi eruption. 

Geophy. Res. Letters, 23-12, 1489-1492. 

Heffter, J.L. and B.J.B. Stunder, 1993: Volcanic 

ash forecast transport and dispersion (VAFTAD) 

model, Weather and Forecasting, 8, 533-541. 
Session 3 – Page 110 

Servranckx, R. and P. Chen, 2004: Modeling 

volcanic ash transport and dispersion: 

Expectations and reality, 2nd International 

Conference on Volcanic Ash and Aviation Safety, 

Alexandria, VA, this volume. 

Szunyogh, I., and Z. Toth, 2002: The effect of 

increased horizontal resolution on the NCEP 

global ensemble mean forecasts. Mon. Wea. Rev., 

130, 1125-1143 
P3.20 

Session 3 – Page 111 

OPERATIONAL VOLCANIC ASH PLUME PREDICTION MODEL PUFF 

AT THE JAPAN AIRLINES 

H. L. Tanaka (Geoenvironmental Sciences, University of Tsukuba, Tsukuba 305-8572 Japan), 

Saburo Onodera (Japan Airlines, Tokyo Japan), and DAISUKE NOHARA (Meteorological 

Research Institute, Tsukuba Japan) 

1. Introduction 

 Volcanic ash cloud floating and traveling 

in the air is a great concern to airline pilots. If a 

commercial jet aircraft encounters ash cloud, the 

damage could be serious enough to cause an 

engine failure (Hobbs et al., 1991; Casadevall, 

1994; Onodera, 1997). In order to avoid serious 

accidents of commercial aircrafts, real-time 

volcanic plume prediction models have been 

developed by some agencies. 

 A 3-D turbulent diffusion model was 

developed by Armienti and Macedonio (1988) 

using an observed upper air wind data and applied 

to stronboli eruption of Mt. St. Helens in 1980. 

Glaze and Self (1991) constructed a turbulent 

diffusion model considering the vertical wind 

shear and applied to Usu volcano in 1977 to see 

distributions of ash fall. Hurst and Turner (1999) 

developed a 3-D turbulent diffusion model called 

ASHFALL to predict volcanic ash fall for 

operational use. In this model, the regional 

distribution of upper air wind is prepared by 

RAMS (Regional Atmospheric Modeling System). 

Turner and Hurst (2001) further combined 

HYPACT (Hybrid Particle and Concentration 

Transport Model) with RAMS to improve the 

model. Heffter and Stunder (1993) developed a 

transport dispersion model called VAFTAD 

(Volcanic Ash Forecast Transport and Dispersion) 

to predict ash plume floating in the air. 

 A group of worldwide volcanic ash 

advisory services was organized to form volcanic 

ash advisory centers (VAACs) by nine 

organizations under the auspice of the 

International Civil Aviation Treaty (ICAO). The 

Tokyo VAAC is one of the nine VAACs, which 

was established in April 1997 at the Tokyo 

Aviation Weather Service Center. The Tokyo 

VAAC operates the Lagrangian and Eulerian 

models to forecast the position of the volcanic ash 

clouds (Tokyo Aviation Weather Service Center, 

2001). 

 In parallel with those activities, a 

real-time volcanic ash plume tracking model 

called PUFF was developed for the purpose of 

real-time aviation safety in northeastern Pacific 

rim including Alaska volcanoes (Tanaka, 1991; 

Kienle et al., 1991; Dean et al., 1993; Tanaka, 

1994; Searcy et al. 1998). It is noted that the 

PUFF model is the earliest ash tracking model 

applied for the aviation safety purpose in a 

real-time operation (Tanaka et al., 1993; Akasofu 

and Tanaka, 1993). The model is operational 

under the Alaska Volcano Observatory (AVO) at 

the Geophysical Institute of the University of 

Alaska Fairbanks (GI/UAF) since the eruption of 

Redoubt volcano in 1990. The PUFF model at 

the University of Tsukuba was applied to the 

actual eruption of Usu volcano on 31 March 2000 

in Hokkaido (Endoh et al., 2001; Tanaka and 

Yamamoto, 2002) and Miyake-jima Volcano on 

August 18 2000. 

 The research product of the PUFF 

prediction system, including the model simulation 

and animation graphics of the simulation results, 

was transplanted to Japan Airlines with the 

assistance by the Japan Weather Association 

(JWA). This report describes the latest 

improvements installed in the PUFF model 

operational at the Japan Airlines. 

2. Description of the model 

 The volcanic plume prediction model 

PUFF was constructed in 1991 and reported in 

detail by Tanaka (1994) and Searcy et al. (1998) as 

an application of pollutant dispersion models. 

The model is based on the three-dimensional (3-D) 

Lagrangian form of the transport-diffusion 

equation. In the Lagrangian framework, a 

realization of the stochastic process of plume 

particles may be described by a random walk 

process (e.g., Chatfield, 1975). Here, the 

diffusion is simulated by a sufficiently large 

number of random variables ri(t), i=1 ~ M, 

representing position vectors of M particles from 

the source S of the volcanic crater. The diffusion 

is superimposed on convective transport and 

gravitational fallout. 
Session 3 – Page 112 

 With a discrete time increment, (t=5 

minutes), the Lagrangian form of the governing 

equation may be written as 

( )

( ) () 





+ ∆ = + ∆ + ∆ + ∆

=

,

0 ,

r t t r t V t D t G t

r S

i i

i 

1 ,

1 ,

i M

i M

~

~

=

=

for

for

0,

0,

>

=

t

t (1)

where ri(t) is a position vector of an i-th 

particle at time t, V is the local wind velocity 

to transport the particle, D is a vector 

containing three Gaussian random numbers 

for diffusion, and G is the gravitational 

fallout speed approximated by Stokes Law. 

 For the computation of convective 

transport, the wind velocity V= (u,v,w) is obtained 

from the global Grid Point Values (GPV) provided 

by Japan Meteorological Agency (JMA). The 

gridded data are first interpolated in time onto the 

model's time steps of every 5 minute. A cubic 

spline method (see Burden et al., 1981) is used to 

interpolate the wind data from 6 hour interval to 

the model's time step. Then, the wind velocity at 

an arbitrary spatial point is evaluated using the 

3-D cubic-splines from the nearby gridded data. 

 The diffusion of the ash particles D=(ch, 

ch, cv) is parameterized by the random walk 

process, where the horizontal and vertical 

diffusion speeds ch, cv may be related to the 

horizontal and vertical diffusion coefficients Kh, Kv. 

We have repeated diffusion tests with various 

values of diffusion coefficients, and the resulting 

dispersals are compared with satellite images of 

actual dispersals for several volcanic eruptions in 

the past (Yamagata, 1993; Yamamoto 2000; 2002). 

With these diffusion tests, we find that the 

appropriate horizontal and vertical diffusion 

coefficients are Kh=150 and Kv=1.5 (m2

 s-1), 

respectively. Note that the values may be 

different for different volcanoes and for different 

weather conditions. 

 The gravitational settling is based on 

Stokes Law as a function of the particle size r. 

The fallout velocity G=(0,0,-vt) is approximated 

by the terminal speed vt of plume particles below: 

 (2)

2

3

2

1

2

2

1

4

1





















−















 + 













 =

o

o

o

t

r

r

r

r

v

v

where v0 (=1.0 m/s) is a reference velocity, and r0

(=150 μm) is the particle size that separates the 

inertial range and viscosity range. In the 

viscosity range, the frictional force of the particle 

is proportional to vt, so the terminal velocity 

becomes a function of r

2

. Whereas, in the inertial 

range, the frictional force is proportional to 2

t v , 

so the terminal velocity becomes a function of r

1/2. 

In the present formulation, the terminal velocity vt

shifts smoothly from the former to the latter 

separated by r0. 

 The actual eruption contains large 

fragments up to few meters in size as well as fine 

ash over a continuous particle size to less than 1 

μm. Large particles settle out within a short 

time, so the particle size spectrum shifts toward 

the smaller particles as time proceeds. Because 

we are interested in the particles which can travel 

for several hours, we have assumed that the initial 

particle size distribution obeys a logarithmic 

Gaussian distribution centered at 100 μm with its 

standard deviation 1.0. Thus, about 95% of 

particles are supposed to have their size between 1 

μm and 1 cm. In practice, the particles larger 

than 1 cm drop quickly within a few time steps of 

the simulation. The particles less than 100 μm 

can travel far from the source providing important 

information of the plume dispersion. 

 Sufficiently large numbers of particles 

are contained within the initial vertical column 

above the crater of the erupting volcano. During 

the 5 min of a time step, the particles are released 

constantly in time from the crater in the model. 

A simple buoyancy model is considered with 

initial upward motion w0 and a constant damping 

rate λ(=1/60s). When the equilibrium plume 

height z2 is given, the initial speed w0 may be 

evaluated from z2, and the vertical plume 

distribution z may be calculated from the 

following form: 

 (3) o t Z Z e λ

λ

ω − = 2 −

Random numbers are generated uniformly in time 

t for the time step of 5 min, which produces dense 

plume particles near the 

top of the plume. The gravitational fallout and 

convective transport during the 5 min are 

calculated for a given time t superimposed on the 

vertical distribution to generate the plume source 

S=(x,y,z). 

 In a case of a short-time explosive 

eruption puff, the ash particles are generated only 

for the initial time of the time integration. When 

the eruption continues for certain period of time, 

the model generates new particles over the same 

vertical column for every time step during the 

specified eruption period. For a steady eruption, 

the particle number tends to increase in the model 

atmosphere before the plume particles have 

dropped or crossed the vertical wall of the model 

domain. Therefore, the number of particles 
Session 3 – Page 113 

released at every time step is adjusted in order to 

draw optimal statistical information from the 

model products. For this reason, we set the 

number of the particles released for a time step as 

100 in this study. Although it is possible to 

increase the number toward the limit of the 

computer capability, the time integration will then 

be considerably slower, which is a disadvantage 

for the urgent case. An excessive complication 

and sophistication are not recommended in the 

application to the real-time operational prediction. 

3. Results 

Figure 1 illustrates an example of the ash 

plume distribution simulated for a hypothetical 

eruption of Etna Volcano. The simulation started 

from 21:00 UTC, 28 July 2004, and the ash 

distribution is for 9 hours after the beginning of 

the eruption. Plume height in feet is designated 

by different colors. The model simulation takes 

about 2 min and the graphics takes about 3 min 

using the SUN Workstation Ultra 60. After the 5 

min of the computation time, we can observe the 

3-D animation of the ash plume dispersal during 

the first 10 hours of the volcanic eruption. 

Figure 1. An example of the ash plume distribution 

simulated for a hypothetical eruption of Etna 

Volcano. The simulation started from 21:00 UTC, 

28 July 2004, and the plot is for 9 hours after the 

eruption. 

The 5 min is the critical time for the 

aviation safety purpose. The model simulation 

can be repeated many times whenever a new 

information, such as the accurate plume height, is 

reported. The model is applicable to any volcano 

in the world, and is routinely running for 

hypothetical eruptions of Sakura-jima, Usu 

Volcano, Miyake-jima, Mt. Asama, Mt. Fuji in 

Japan, Redoubt volcano, Augustine volcano in 

Alaska, and Etna volcano in Italy. Those PUFF 

model simulations may be seen at the following 

web site. 

(http://air.geo.tsukuba.ac.jp/puff/index.html) 

4. Concluding Summary 

 Volcanic ash cloud floating and traveling 

in the air is a dangerous object for commercial and 

non-commercial aircrafts. In order to avoid 

encounters with ash cloud, a real-time volcanic 

plume prediction model, called PUFF, has been 

developed in 1991 and reported by Tanaka (1994) 

and Searcy et al. (1998) for Alaska volcanoes. 

The performance of the ash tracking accuracy has 

been checked whenever actual eruptions occur in 

the world. The demonstration to real eruptions of 

Usu volcano and Miyake-jima are reported to 

assess the performance of the model for tracking 

the airborne ash clouds for the aviation safety 

purpose (Tanaka and Yamamoto, 2002). The 

PUFF model has been updated, and the latest 

version as described in this report is installed at the 

flight operation system in the Japan Airlines. 

 Since the establishment of ICAO's 

VAACs, volcanic plume tracking becomes 

operational in the world, providing useful 

information to aviation industry. Along with the 

VAACs, we need further to improve the accuracy 

of the PUFF model by accumulating experience in 

the flight operations and by establishing timely 

notification system to pilots with much 

user-friendly graphic interface. 

Acknowledgments 

 

 The authors are grateful to the support 

rendered by Drs. S. Akasofu, K. Dean, J. Dehn of 

the University of Alaska. Thanks are extended to 

Mr. S. Shimoda and Ms. S. Yamagata of JWA for 

their technical support. The authors appreciate 

Ms. K. Honda for her technical assistance. This 

research was supported by the IARC/NASDA 

research project: Modeling the dynamics of 

volcanic eruption cloud, and by Asahi Breweries 

Foundation. 

References 

Akasofu, S.-I. and H. L. Tanaka, Urgent issue 

of developing volcanic ash tracking model, 

Kagaku Asahi, 5, 121-124 (in Japanese), 

1993. 
Session 3 – Page 114 

Armienti, P. and G. Macedonio, A numerical 

model for simulation of tephra transport 

and deposition: Application to May 18, 

1980, Mount St. Helens eruption, J. 

Geophys. Res., 93, 6463-6476, 1988. 

Burden, R. L., J. D. Faires, and A. C. 

Reynolds, Numerical analysis, Prindle, 

Weber and Schmidt, 598 pp, 1981. 

Casadevall, T. L., The 1989-1990 eruption of 

Redoubt volcano, Alaska: Impacts on 

aircraft operations, J. Volcanol. Geotherm. 

Res., 62, 301-316, 1994. 

Chatfield, C., The analysis of time series: An 

introduction, Chapman and Hall, 286 pp, 

1975. 

Dean, K. G., S. I. Akasofu, and H. L. Tanaka, 

Volcanic hazards and aviation safety: 

Developing techniques in Alaska, FAA 

Aviation Safety Journal, Vol. 3, No. 1, 

11-15, 1993. 

Endoh, K., M. Ohno, M. Kunikita, M. 

Morohoshi, M. Suzuki, Y. Nishimura, D. 

Nagai, T. Chiba, and I. Tohno, 

Pheatomagmatic explosions of the 2000 

eruption of Usu volcano, Natural Science 

Reports, Nihon University, 36, 65-73 (in 

Japanese), 2001. 

Glaze, L. S. and S. Self, Ashfall dispersal for 

the 16 September 1986, eruption of Lascar, 

Chile, calculated by a turbulent diffusion 

model, Geophys. Res. Let., 18, 1237-1240, 

1991. 

Heffter, J. L. and B. J. B. Stunder, Volcanic ash 

forecast transport and dispersion 

(VAFTAD) model, Computer Techniques, 

8, 533-541, 1993. 

Hobbs, P. V., L. F. Radke, J. H. Lyons, R. J. 

Ferek, D. J. Coffman, and T. J. Casadevall, 

Airborne measurements of particle and gas 

emissions from the 1990 volcanic eruption 

of Mount Redoubt, J. Geophys. Res., 96, 

18735-18752, 1991. 

Hurst, A. W. and R. Turner, Performance of 

the program ASHFALL for forecasting 

ashfall during the 1995 and 1996 eruptions 

of Ruapehu volcano, New Zealand, J. Geol. 

and Geophys., 42, 615-622, 1999. 

Kienle, J., A. W. Woods, S. A. Estes, K. 

Ahlnaes, K. G. Dean, and H. L. Tanaka, 

Satellite and slow-scan television 

observations of the rise and dispersion of 

ash-rich eruption clouds from Redoubt 

volcano, Alaska, EOS, Vol. 72, 2, 748-750, 

1991. 

Onodera, S., Volcanic activity and flight 

operations, Aviation Meteorological Notes, 

45, 13-30, 1997. 

Searcy, C., K. Dean, and B. Stringer, PUFF: A 

volcanic ash tracking and prediction model, 

J. Volc. and Geophys. Res., 80, 1-16, 1998. 

Suck, S. H., E. C. Upchurch, and J. R. Brock, 

Dust transport in Maricopa county, Arizona, 

Atmos. Environ., 12, 2265-2271, 1978. 

Tanaka, H. L., Development of a prediction 

scheme for the volcanic ash fall from 

Redoubt volcano, First Int'l. Symp. on 

Volcanic Ash and Aviation Safety, Seattle, 

Washington., U.S. Geological Survey 

Circular 1065: 58, 1991. 

Tanaka, H. L., K. G. Dean, and S. I. Akasofu, 

Predicting the movement of volcanic ash 

clouds, EOS, Vol. 74, No .20, 231-231, 

1993. 

Tanaka, H. L., Development of a prediction 

scheme for volcanic ash fall from Redoubt 

volcano, Alaska, Proc. First International 

Symposium on Volcanic Ash and Aviation 

Safety. U.S. Geological Survey, Bulletin 

2047, 283-291, 1994. 

Tanaka, H.L., and K. Yamamoto, Numerical 

Simulations of volcanic plume dispersal 

from Usu volcano in Japan on 31 March 

2000. Earth, Planets and Space, 54, 

743-752, 2002. 

Tokyo Aviation Weather Service Center, 

Volcanic ash advisory service, Japan 

Meteorological Agency, Geophys. Maga. 

Ser. 2, Vol. 4, No. 1-4, 2001. 

Turner, R. and T. Hurst, Factors influencing 

volcanic ash dispersal from the 1995 and 

1996 eruptions of Mount Ruapehu, New 

Zealand, J. Appl. Meteor., 40, 56-69, 2001. 

Yamagata, S., Development of volcanic plume 

prediction scheme for aviation safety, 

Graduation Thesis, Natural Science, 

University of Tsukuba, 136 pp, 1993. 

Yamamoto. K., Numerical experiment of the 

volcanic ash cloud dispersion and the 

justification by satellite image, Graduation 

Thesis, Natural Science, University of 

Tsukuba, 87 pp, 2000. 

Yamamoto, K., Numerical experiments and the 

assessment for the probability of the 

volcanic ash dispersal, Master thesis, 

Graduate School of Life and 

Environmental Sciences, University of 

Tsukuba, 70 pp, 2002.
P3.21 

Session 3 – Page 115 

DETECTING ASH CLOUDS IN TROPICAL ATMOSPHERES 

I.M. Watson, W.I. Rose, G.J.S. Bluth. 

Dept. of Geological Mining Engineering and Sciences, Michigan 

Technological University, Houghton, MI, 49931, USA 

Abstract 

Current mapping and retrieval 

algorithms applied to volcanic ash are 

susceptible to interference from atmospheric 

water vapor. Whilst this interference is well 

documented and understood in an 

operational context, quantification of the 

effect has remained elusive. A forward 

model has been developed that calculates the 

effects water vapor has on the ‘splitwindow’ ash signal using a combination of a 

Mie-scattering code embedded in a 

MODTRAN-based atmosphere (Watson et 

al., in prep). Initial results from the model 

suggest a brightness temperature difference 

‘cost’ of 1-3 degrees K when considering an 

ash cloud from a Northern latitude in a 

tropical atmosphere. 

There is a strong dependence of the 

effect of water vapor on the optical depth of 

the cloud: thicker, higher clouds, 

transmitting less of the contribution of 

radiance from the underlying surface are less 

strongly affected than thinner, lower clouds 

where the surface contribution is more 

significant. This discovery has important 

ramifications in terms of ash cloud detection 

and tracking. (1) Initial stages of eruptive 

activity are relatively independent of 

atmospheric conditions, and (2) ash clouds 

in tropical atmospheres will become less 

detectable much more quickly as the water 

vapor signal swamps the negative brightness 

temperature difference signal. 

Theory 

A forward model has been 

developed (Watson et al., in prep.) that 

embeds a Mie-scattering aerosol model 

within a MODTRAN atmosphere. The 

model facilitates investigation of the 

sensitivity to key parameters that are 

typically either assumed or acquired from 

data external to the satellite image. These 

parameters can include (1) the volcanic 

ash’s chemical composition and particle size 

distribution (defined by its effective radius, 

variance and total number of particles) (2) 

the atmosphere’s temperature, pressure and 

relative humidity profile as a function of 

height (3) the ash clouds height and depth 

and (4) the underlying surface’s temperature 

and emissivity (figure 1). 

Figure 1. 

 

Radiative transfer is treated by the model in 

three stages; (1) the ground-leaving radiance 

(defined by the ground temperature and 

emissivity) is passed through the atmosphere 

to the base of the plume. The atmospheric 

contribution to the upwelling radiance is 

added to yield the radiance at the cloud base; 

(2) this radiance is transmitted through the 

cloud, using both the transmission of the 

atmosphere (MODTRAN-derived) and the 

plume (Mie model derived) and again 

atmospheric upwelling radiance is added to 

yield the cloud-top radiance; (3) finally, the 

cloud top radiance is the then transmitted 
Session 3 – Page 116 

through the portion of the vertical path 

above the plume and again path-added 

upwelling radiance from the atmosphere 

added to yield the at-satellite radiance. This 

model was tested against a single layer 

MODTRAN model (without the presence of 

volcanic aerosol in the ‘in’ layer) in order to 

validate the three-layer assumption. 

Methodology 

The model can be used to determine 

the effects of water vapor on current 

detection (Prata 1989 a and b) and retrieval 

algorithms (Wen and Rose, 1994; Rose et 

al., 1995, 2000, 2001 and 2003; Yu and 

Rose 2003) and validate previous 

atmospheric correction attempts (Yu et al., 

2002).

 

Figure 2. 

Figure 2. (after Watson et al., 2004) 

(A) the spectral response functions of the 

MODIS instrument (B signature of andesitic 

ash and (C) an example atmospheric 

transmission spectrum

The forward model is operated 

through a graphical user interface, allowing 

the user to input the ash, cloud and 

atmospheric data into the model. The model 

then calculates the at-satellite radiance for 

the given parameters. Separate transmission 

spectra for just andesitic ash and a clear 

atmosphere can be seen in figure 2. 

The split window algorithm 

calculates the brightness temperature 

difference channels 31 and 32 of the 

Moderate Resolution Imaging 

Spectroradiometer (MODIS), which are 

analogous to channels 4 and 5 of the 

Advanced Very High Resolution 

Radiometer (AVHRR) and the 

Geostationary Operational Environmental 

Satellite (GOES). It can be seen from figure 

2 that between 11 and 12 μm the slopes of 

the two transmission spectra are in 

opposition. Therein lies the answer to how 

the split window algorithm is affected by 

water vapor; if the two spectra are 

convolved (multiplied together) the ash’s 

spectral signature, what we are using to 

detect the presence of ash, is washed out by 

water vapor. The more water vapor is added 

the more the ash signal is hidden.

Example results were derived using 

a Northern latitude and tropical atmosphere 

for comparison. At-satellite radiances were 

derived for both cold, dry and warm, wet 

atmospheres. In both cases 2.0 μm andesite 

ash particles in a lognormal distribution 

(with a variance of 0.74) were used to 

represent loading of the atmosphere at a 

height of 10 km and a cloud thickness of 1 

km. Preliminary results are shown below. 

Results

All other things being equal 

(including ground temperature and 

emissivity) the presence of water vapor 

reduces the positive slope of the at-satellite 

radiance spectrum. This effect can be more 

strongly seen if the radiance value is 

converted to brightness temperature using 

the Planck function (figure 3.). Here, the 

wavelength range is reduced to highlight the 

area between 10 and 13 μm that the split 

window retrieval uses to locate ash – the 

brightness temperature difference (BTD) 

algorithm (Prata et al., 1989 a and b; Wen 

and Rose, 1994). In this example the change 

in BTD is about 1.8 K. This has a significant 

effect on the detectability of volcanic ash as 

much of the fringes of typical volcanic ash 
Session 3 – Page 117 

clouds have BTD values of this order or 

less. 

Figure 3. 

260

262

264

266

268

270

10 11 12 13

wavelength in μm

BT in K

Figure 3. Brightness temperature (BT) 

spectra for 2.0 μm andesitic ash in a wet 

(grey line) and dry (black line) atmosphere. 

Note again the change in gradient between 

11 and 12 μm for the two examples, as 

indicated by the straight lines. 

It is possible to show how significant a ~ 2K 

effect on the detection of volcanic ash by 

taking a known northern latitude eruption 

and ‘moving it’ to the tropics (figure 4). 

Such an example has been calculated for the 

September 1992 Mt. Spurr eruption (Watson 

et al., in prep). Figure 4 shows the Spurr 

eruption cloud captured by AVHRR at 1700 

UT on 17th September 1992 (see Schneider 

et al., 1995 for more details) in (a) an 

atmosphere that represents, as accurately as 

possible, the Aleutian atmosphere into 

which the cloud was injected and (b) a 

tropical atmosphere above Guadeloupe that 

causes a 2K suppression of the brightness 

temperature difference signal. What is 

immediately apparent is that the are of the 

detectable part of the cloud is dramatically 

reduced (by the order of 50 %). A 2 K cost 

is by no means extreme (3.5 K has been 

observed in some model runs) and, can 

clearly be seen to remove significant fringes 

from the cloud when using zero as a BTD 

cut off. 

Figure 4. 

a 

b 

Figure 4. Example ash map indicating the 

change in area for the September 1992 Mt. 

Spurr eruption cloud (above the Caribbean 

volcanic arc) with enough water vapor in the 

atmosphere to change the BTD by (a) 0 and 

(b) -2 K respectively.

Preliminary conclusions 

Forward modeling can be used to 

quantitatively determine the effects of 

different water vapor concentrations on the 

‘split-window’ signal. Water vapor more 

strongly affects clouds that are optically 

thinner as relative proportions of signal from 

the underlying ground (and water vapor) 

increase. Lower (optically thick) clouds with 

larger particles (per constant volume) will be 

more strongly affected than higher clouds 

with smaller particles. Clouds with larger 

particles (of equivalent mass/volume) will 

be more strongly affected than clouds with 

smaller particles. Thus, water vapor effects 

are a complex function of water vapor 

content, cloud height, cloud opacity and 
Session 3 – Page 118 

particle size and must be treated as such.

The ‘cost’ in BTD varies from -0.8 

(atypical) to 3.5 K and usually ranges from 

+1 to +3 K in clouds of optical depth 0.2 to 

0.9. Cloud areas and tonnages can be 

reduced to 10% or less of their high latitude 

analogues (Watson et al., in prep). 

References 

Prata, A.J., Infrared radiative transfer 

calculations for volcanic ash clouds, 1989a

Geophysical Research Letters, Vol. 16, pp. 

1293-1296 

Prata, A.J., Observations of volcanic ash 

clouds in the 10-12 m window using 

AVHRR/2 data, 1989b, International 

Journal of Remote Sensing, Vol. 10, pp. 751-

761 

Rose, W I, D. J. Delene, D. J. Schneider, G. 

J. S. Bluth, A. J. Krueger, I. Sprod, C. 

McKee, H. L. Davies and G. G. J. Ernst, 

1995, Ice in the 1994 Rabaul eruption cloud: 

implications for volcano hazard and 

atmospheric effects, Nature, 375: 477-479. 

Rose, W I, G J S Bluth and G G J Ernst, 

2000, Integrating retrievals of volcanic 

cloud characteristics from satellite remote 

sensors--a summary, Philosophical 

Transactions of Royal Society, Series A, vol. 

358 no 1770, pp. 1585-1606. 

Rose, W I, G J S Bluth, D J Schneider, G G 

J Ernst, C M Riley and R G McGimsey 

2001, Observations of 1992 Crater 

Peak/Spurr Volcanic Clouds in their first 

few days of atmospheric residence, Journal 

of Geology, 109: 677-694.

Rose, W I, Y Gu, I M Watson, T Yu, GJS 

Bluth, A J Prata, A J Krueger, N Krotkov, S 

Carn, M D Fromm, D E Hunton, G G J 

Ernst, A A Viggiano, T M Miller, J O 

Ballentin, J M Reeves, J C Wilson, B E 

Anderson D Flittner, 2003, The FebruaryMarch 2000 eruption of Hekla, Iceland from 

a satellite perspective, AGU Geophysical 

Monograph 139: Volcanism and the Earth's 

Atmosphere, ed by A Robock and C 

Oppenheimer, pp. 107-132. ISBN 0-87590-

998-1 

Schneider, D. J., W. I. Rose and L. 

Kelley, 1995, Tracking of 1992 eruption 

clouds from Crater Peak/Spurr Volcano 

using AVHRR, U. S. Geol. Surv. Bull. 

2139 (Spurr Eruption, edited by T. 

Keith), 27-36. 

Watson, I.M., Realmuto, V.J., Rose.,W.I., 

Bluth G.J.S., Forward modeling of volcanic 

cloud transmissions through different 

atmospheres, in preparation for Journal of 

Geophysical Research – Atmospheres 

Watson, I.M., Realmuto, V.J., Rose, W.I., 

Prata, A.J., Bluth, G.J.S., Gu, Y., C. E. 

Bader, Yu, T., 2004 Thermal infrared 

remote sensing of volcanic emissions using 

the Moderate Resolution Imaging 

Spectroradiometer (MODIS), Journal of 

Volcanology and Geothermal Research, Vol. 

135, pp. 75-89

Wen, S and W I Rose, 1994, Retrieval of 

Particle sizes and masses in volcanic clouds 

using AVHRR bands 4 and 5, Journal of 

Geophysical Research, 99:5421- 5431.

Yu, T W I Rose and A J Prata, 2002, 

Atmospheric correction for satellite-based 

volcanic ash mapping and retrievals using 

"split window" IR data from GOES and 

AVHRR, Journal of Geophysical Research, 

106: No D16, 10.1029.

Yu, T and W I Rose, 2000, Retrieval of 

sulfate and silicate ash masses in young (1-4 

days old) eruption clouds using multiband 

infrared HIRS/2 data, AGU Monograph 116 

--Remote Sensing of Active Volcanism, ed by 

P Mouginis-Mark, J Crisp and J Fink, pp. 

87-100.

 
P3.22 

Session 3 – Page 119 

ERUPTION CLOUD ECHO MEASURED WITH C-BAND WEATHER RADAR

Yoshihiro Sawada 

Faculty of Science, Hokkaido University, Sapporo, Japan 

Abstract 

Careful inspections of radar echo-data in Japan 

showed that eruption clouds by fairly smaller sized 

eruptions can be registered with C-band weather 

radars. Aggregation of fine ash particles and 

water-coated ash particles inside eruption clouds are 

considered as the reason of detection. 

Introduction 

C-band weather radars are commonly operated for 

weather observation in many countries having active 

volcanoes, and eruption clouds by strong volcanic 

eruptions have been registered as radar echoes. 

However, almost no observation is reported for 

smaller eruption cloud. Radar data of C-band 

weather radars in Japan were inspected and several 

echoes were obtained (Sawada, 2003b). The reason 

of detection is considered. 

Report of Eruption Cloud with Weather Radar 

According to the database of Smithsonian Institution 

during a period since 1970 through 2003, 

observations of eruption clouds as echoes with 

weather radars are reported. In addition to the data, 

the author inspected and gathered radar data in Japan 

obtained with weather radars of Japan 

Meteorological Agency (JMA). Results in papers are 

inspected, too. The volcanoes of which eruption 

clouds were detected as radar echoes counted 13 

with 23 eruptions as shown in Table 1. 

Wavelength of C-band radar (wavelength of 5 cm) is 

basically too long to detect fine ash particle (mm-μm 

in size) of eruption cloud. In general, it is considered 

that major portion of eruption cloud composed with 

accumulated large sized particles, high 

distribution-density of particles and high content of 

water/ ice particles can be detected as echoes. 

Actually, the big eruption columns such as 1980 

Mount St. Helens, 1991 Pinatubo and 1992 Spurr 

were well detected, and major extents & top altitudes 

were well monitored with time (Smithsonian 

Institution Web site, Harris et al.,1981 and Oswald et 

al.,1996). Doppler radar system can measure 

movements of ash/ water particles, and is very 

effective to monitor small eruption clouds. Small & 

not so dense ash plumes lower than 5 km in heights 

from Popocatepetl, Mexico were well detected 

(Table 1). 

Observation Result in Japan 

ECE (Eruption Cloud Echo) by Large-Sized 

Eruption 

JMA operates 29 C-band weather radars in Japan; 20 

stations with wavelength of 5.7cm, power of 250 - 

300 kW & detection range of 300 km, and 9 airport 

stations with power of 200 kW & detection range of 

100 km. 

Eruption clouds higher than 9 km by four strong 

eruptions of 1973 Tyatya, 1977 Usu, 1986 

Izu-Oshima and 2000 Miyake-jima were obtained as 

clear ECEs by the radars (Table 1). 

1973 July 14 Tyatya Eruption

ECEs were observed with Kushiro radar (ca. 220 km 

SW of the volcano). Eruptions simultaneously 

occurred from two craters (Abdurakmanov et al., 

1999) and the double ECEs were clearly monitored 

( Photo 1, Japan Meteorological Agency, 1974)). 

1977 August 7, 8 & 9 Usu Eruption 

ECEs were observed with radars of Sapporo (ca. 70 

km NE of the volcano) and Hakodate (ca. 80 km 

SSW). Analysis of PPI (Plan-Position Indicator) and 

RHI

Photo 1 Double eruption cloud echoes (white arrows) of 

July 14, 1973 Tyatya Eruption tracked with Kushiro 

weather radar (Japan Meteorological Agency, 1974) 

Kushiro Radar 200km

11:41JST

12:21JST
Session 3 – Page 120 

Table 1. List of volcanoes of which eruption clouds were detected with radars during 1970 - 2003 

 *: Visual Measurement; ** : Doppler Radar; *** : X-band Radar 

 Observation Date Volcano Max. Height of 

 Eruption Cloud 

 1970 May 5 Hekla, Iceland 15 (1) km 

 1973 July 14, 17, 18 Tyatya (Kunashir) 9 (2) 

 1976 Jan. 23 Augustine, Alaska 14 (1) 

 1977 Aug. 7, 8, 9 Usu, Hokkaido 9.7 (3) 

 1980 May 8, June, July Mt St. Helens (Washington) >25 (4) 

 1981 Apr. 9 Hekla (Iceland) 6.6 (1)

 1981 May 15 Pagan (Mariana Islands) 18 - 20 (1)

 1984 July 7 Sakura-jima (Kyushu) 2.1* (5)

 1986 Nov. 21 Izu-Oshima (Izu Islands) 10 - 12 (6)

 1991 Jan. 17 Hekla (Iceland) 11.5 (1)

 1991 June 12, July 27, Aug. 5 - 11 Pinatubo (Philippines) 16.5 (1) (7) 

 1991 June 3, 8, 12 Unzen (Kyushu) 6.5 (8) (9)

 1992 June 27, Aug. 18 - 21, Sep. 17 Spurr (Alaska) 18 (1)

 1992 Aug. 20, 21, Sep. Pinatubo (Philippines) 9 (1) 

 1992 Feb. 5 Unzen (Kyushu) Not obs.* (8) 

 1993 May 21 Unzen*** (Kyushu) 4* (10) 

 1996 July 16 Sakura-jima** (Kyushu) 0.6* (11) 

 1996 Dec. 14 Sakura-jima (Kyushu) Not obs.* (12) 

 1998 Feb. 11, Sep. 8, 22, Oct. 17 Popocatepetl** (Mexico) 4* (1) 

 1999 Mar. 11, 18, Apr. 4, 11 Popocatepetl** (Mexico) Not obs.* (1) 

 2000 Feb. 26 – 27 Hekla (Iceland) 12* (13)

 2000 Mar. 31 Usu (Hokkaido) 3.5* (14) 

 2000 Aug. 10, 18, 29 Miyake-jima (Izu Isls.) 16 - 17* (15) 

(1) Smithsonian Institution, (2) JMA (1974), (3) JMA (1980), (4) Harris et al. (1981), (5) Uehara 

et al. (1985), (6) Seis. & Volc. Dep. (1987), Takano (1987), (7) Oswalt et al. (1996), (8) Niina 

(1992), Fukuoka DMO (1996), (9) Tanegashima WS (1992), (10) Arao et al. (1996), (11) 

Fukui et al. (1997), (12) Tanegashima WS (1998), (13) Lacasse et al. (2004), (14) by the 

courtesy of Sapporo DMO, Sawada (2003b), (15) by the courtesy of Tokyo DMO, Sawada 

(2003b) Where, JMA: Japan Meteorological Agency, Seis. & Volc. Dep.: Seismological and 

Volcanological Department, DMO: District Meteorological Observatory and WS: Weather 

Station. 

(Range Height Indicator) data showed horizontal 

moving velocities and approximate vertical profiles 

of eruption columns, respectively (Japan 

Meteorological Agency, 1980). 

1986 November 21 Izu-Oshima Eruption 

ECEs were observed with 4 radars; Fuji (wavelength 

of 10.4 cm & detection range of 500 km, ca. 100 km 

NW of the volcano, operated by 1999), Tokyo (ca. 

110 km NNE), Haneda airport (ca. 100 km NNE) 

(Seismological and Volcanological Department, 

1987) and Nagoya (ca. 220 km WNW) (Takano, 

1987). Extent of the ECE v.s. that with satellite 

image was under the ratio of one : several tens 

(Sawada, 2003a). 

2000 August 18 Miyake-jima Eruption 

ECEs were tracked with Shizuoka radar (ca. 145 km 

NW of this volcano) (by the courtesy of Tokyo 

District Meteorological Observatory, Sawada 、

2003b). 

ECE by Small-Sized Eruption 

7 ECEs by small eruptions with cloud-top lower 

than 4 km were detected in Japan (Table 1), while 2 

ECEs of 1993 Unzen & 1996 July Sakura-jima are 

with X-band and Doppler radars, respectively. 
Session 3 – Page 121 

Sakura-jima (South of Kyushu)

Kagoshima airport radar (ca. 25km NNE of the 

volcano) detected ECE on July 7, 1984 as shown in 

Fig. 1 (Uehara et al., 1985). Its cloud top was 2.1km 

and extent of ECE was about 3 km x 3km over the 

crater. 

Weak & small ECEs were obtained on December 14, 

1996 with Tanegashima radar (ca. 102 km SSE of 

the 

Fig. 1 Eruption cloud echo (solid arrow) of Sakura-jima 

eruption on July 7, 1984 obtained with Kagoshima airport 

weather radar (Uehara et al., 1985 (modified)) 

Fig. 2. Eruption cloud echo (solid arrow) of Sakura-jima 

eruption on December 14, 1996 with Tanegashima radar 

(Tanegashima Weather Station, 1998 (modified)) 

volcano) ( Fig. 2). The eruption occurred before 

dawn, and its cloud-top was not observed due to 

darkness. However, the size of eruption was at 

ordinary level (Tanegashima Weather Station, 1998). 

Unzen (SW of Kyushu)

ECEs accompanied by pyroclastic flows on June 3 

& 8, 1991 and by eruptions with lapilli-ejections on 

June 12 were obtained with Fukuoka radar (about 80 

km N of the volcano). ECEs in February, 1992 were 

very weak ones. (Niina, 1992, Fukuoka District 

Meteorological Observatory, 1996). The ECEs on 

June 8 were also registered with Tanegashima 

weather radar (ca. 235 km SSE) of the volcano 

(Tanegashima Weather Station, 1992). The ECEs on 

June 3 drifted eastward and could be tracked across 

the Ariake Inland Sea reaching over Kumamoto City, 

ca. 36km ENE of the volcano (Fig. 3). 

Fig. 3. Eruption cloud echoes of pyroclastic flows (white 

arrows) at Unzen on June 3, 1991 tracked with Fukuoka 

weather radar (Niina, 1992, Fukuoka District 

Meteorological Observatory, 1996 (modified)) 

Usu (SW of Hokkaido)

Phreatomagmatic eruptions occurred with 3.5 km 

high eruption clouds on March 31, 2000. Only 

possible small echoes (one-two pixels) moving 

eastward were detected twice on the day with 

Hakodate weather radar (ca. 70 km S of the volcano) 

(by the courtesy of Sapporo District Meteorological 

Observatory, Sawada, 2003b). 

SAKURA-JIM

Kago shima Airport 

 Weather Radar 

SAKURA-JIMA

18:25JST 

 10 km 

Tanegashima 

 Weather Radar

05:30JST 

SAKURA-JIMA

 100 km 

UNZEN

 16:15JST 

16:30JST 16:37JST 

Ariake Sea

Kumamoto

30 km
Session 3 – Page 122 

Discussion 

Why can C-band weather radar observe ECEs of 

small volcanic eruptions ? 

Cloud top of June 8, 1991 Unzen ECE with RHI 

was 6.5 km and radar reflection from the upper ECE 

was weaker than that from the lower (Niina, 1992). 

He considered that weaker reflection was due to fall 

out of ash particles from the upper cloud, while those 

fallen particles accumulated at the lower ECE causes 

stronger radar reflections. 

Arao et al. (1996) observed about 4 km tall ash 

clouds accompanied by pyroclastic flows with 

X-band radar (wavelength of 3.2 cm) at Unzen on 

May 21 1993. The radar reflection from the upper 

ECE was stronger than that from the lower. They 

discussed that ash particles in the upper cloud were 

aggregated and were coated with water due to 

cooling of water-vapor under high humidity in 

eruption cloud & upper surrounding air. At the lower 

cloud, fallen ash particles dispersed due to low 

humidity conditions in and outside the ECE. They 

showed that radar reflections from water-coated 

particles increase compared with those from dry 

particles. 

ECEs of February, 2000 Hekla Eruption were very 

well and for long time tracked with C-band radar, 

and the effects with high contents of water or ice 

particles are discussed for the reason (Lacasse et al., 

2004). 

Fig. 4. Overlay of the detection range at 2000m of JMA’s 

weather radar network and active volcanoes in Japan. 

(after instruction data of Japan Meteorological Agency) 

Small and possibly thin ECEs of ash clouds by 

pyroclastic flows at Unzen on June 3, 1991 could be 

tracked at east-side around Kumamoto city , about 

34 km from the volcano (Fig. 3). There were rain 

clouds in the area, and high humidity may cause 

water-coatings & aggregation of fine ash particles in 

the small ECEs. 

In addition to water vapor content in eruption clouds, 

high water contents due to phreatomagmatic 

eruptions, existence of underground water, and high 

humidity conditions of surrounding air may 

accelerate to generate water-coated ash particles and 

to aggregate ash particles in eruption clouds. These 

eruption clouds will be detected and tracked with 

C-band weather radars. 

Conclusion 

Not only ECEs by large-sized eruptions, but also by 

small volcanic eruptions could be detected by 

C-band weather radars. It is considered that water 

coatings and aggregations of ash particles enabled to 

be detected as ECEs. However, it is hard to 

discriminate ECEs from rain clouds. 

The detection range of JMA’s radar network can 

cover most of active volcanoes in Japan (Fig. 4). 

Recently, airport weather radars are being reinstalled 

as doppler type systems. By the network, it is 

expected to observe ECEs by not only radars near 

volcanoes but also those far from eruption sites. 

Detection capability of ECEs by the network is up to 

the strength of eruption, weather condition and 

topographical condition between radar sites and 

volcanoes, but further high detection rate is expected 

with the combinations of weather radars. It will be 

possible to detect ECEs of eruption clouds higher 

than 5 km except insular volcanoes in the ocean with 

JMA’s C-band weather radar network under good 

conditions. 

Acknowledgement 

The author gratefully acknowledges to the personnel 

at radar observatories of Japan Meteorological 

Agency for providing of the radar data for this 

research work. 
Session 3 – Page 123 

References 

Abdurakmanov, A. I. and Steinberg, G. S. (1999): 

Tyatya volcano – Morphology and geological 

structure of the volcano. Institute of Volcanology and 

Geodynamics Russian Academy of Natural Science, 

1-20 

Arao, K., Iwasaki, H., Fukui, K., Hayakawa, Y. and 

Takeda, T. (1996): A case study of structure and 

evolution of the ash cloud derived from Unzen 

pyroclastic flow using radar data. Bulletin of 

Volcanological Society of Japan, v. 41, 149-158 (in 

Japanese with English abstract and captions) 

Fukuoka District Meteorological Observatory (1996): 

Pyroclastic flow on June 8, 1991 of Unzen observed 

with weather radar. Memoirs of Fukuoka 

Meteorological Observatory, v. 51, 71-75 (in 

Japanese) 

Fukui, K., Mori, T. and Churei, M. (1997): Observation 

of volcanic plume from Sakura-jima with doppler 

radar. Abstract of Session of Meteorological Society 

of Japan, v. 71, 226 (in Japanese) 

Harris, D. M., Rose W. I. Jr., Roe R. and Thompson M. 

R. (1981): Radar observations of ash eruptions at 

Mount St. Helens volcano, Washington. The 1980 

Eruptions of Mount St. Helens, Washington: U. S. 

Geological Survey Professional Paper, v. 1250, 

323-333 

Japan Meteorological Agency (1974): Volcanic 

activities after the 1973 June 17 Earthquake off 

Nemuro Peninsula. Technical Report of Japan 

Meteorological Agency, v. 87, 3, 17-18 & 101-102 

(in Japanese) 

Japan Meteorological Agency (1980): The 1977 

August – 1978 December Eruption of Usu. 

Technical Report of Japan Meteorological Agency, v. 

99, 7-14 & 193 (in Japanese) 

Lacasse, C., Karlsdottir, S., Larsen, G., Soosalu, H., 

Rose, W. I., and Ernst, G. G. J. (2004): Weather radar 

observations of the Hekla 2000 eruption cloud, 

Iceland. Bulletin of Volcanology, v. 66, 457 – 473 

Niina, Y. (1992): Radar echoes obtained by Fukuoka 

weather radar, of eruption clouds with pyroclastic 

flows at Fugen-dake, Unzen. Radar-KansokuGijutsu-Shiryou of Japan Meteorological Agency, v. 

41, 41-52 (in Japanese) 

Oswalt, J. S., Nichols W. and O’hara J. F. (1996): 

Meteorological observations of the 1991 Mount 

Pinatubo Eruption. Fire and Mud: Newhall, C. G. 

and Punongbayang R. S. edt., Philippine Institute of 

Volcanology and Seismology and University of 

Washington Press, 625-636 

Sawada, Y. (2003a): Study on observation and analysis 

of eruption cloud with imagery of Geostationary 

Meteorological Satellite (HIMAWARI). Journal of 

Meteorological Research of Japan Meteorological 

Agency, v. 55, 57-152 (in Japanese with English 

abstract and captions) 

Sawada, Y. (2003b): Eruption cloud echo observed 

with JMA’s C-band weather radar. Sokko-jihou of 

Japan Meteorological Agency, v. 70, 119-169 (in 

Japanese) 

Seismological and Volcanological Department (1987): 

The 1986 Eruption of Izu-Oshima. Special Report 

Series of Natural Disasters of Japan Meteorological 

Agency, v. 1 in 1987, 90-91 & 148-152 (in Japanese) 

Smithsonian Institution Website: http://www. volcano.

si.edu (accessed 2004-07-17) 

Takano, S. (1987): Recent Radar Observations (84)-

Echoes by the Izu-Oshima Eruption Clouds. 

Geophysical Notes of Tokyo District Meteorological 

Observatory, v. 88, 1 (in Japanese) 

Tanegashima Weather Station (1992): Echoes by the 

large pyroclastic flows of Fugen-dake, Unzen (1991 

June 8). Radar-Gijutu-Uchiawasekai- Shiryou of 

Japan Meteorological Agency in 1991, 74 & 77 (in 

Japanese) 

Tanegashima Weather Station (1998): Radar echoes 

possibly by eruptions of Sakura-jima. RadarGijutsu-Uchiawasekai-Shiryou of Japan 

Meteorological Agency in 1997, 27-28 (in Japanese) 

Uehara, M., Taira, T. and Fukunaga, S. (1985): Weather 

radar system at Kagoshima airport station. 

Radar-Kansoku-Gijutsu-Shiryou of Japan 

Meteorological Agency, v. 34, 28-32 (in Japanese) 
4.1 

Session 4 – Page 1 

THE INTERNATIONAL AIRWAYS VOLCANO WATCH (IAVW) 

Raul Romero 

International Civil Aviation Organization, Montreal, Canada 

1. INTRODUCTION 

 The definition of the IAVW is included in ICAO 

Annex 3 — Meteorological Service for International Air 

Navigation to the Convention on International Civil Aviation 

and reads as follows: 

International airways volcano watch (IAVW). International 

arrangements for monitoring and providing warnings to 

aircraft of volcanic ash in the atmosphere. 

[Note: The IAVW is based on the cooperation of aviation and 

non-aviation operational units using information derived from 

observing sources and networks that are provided by States. 

The watch is coordinated by ICAO with the cooperation of 

other concerned international organizations.]

2. HISTORICAL BACKGROUND 

 The IAVW was first established in 1987 with an 

amendment to Annex 3, which introduced a requirement for 

the international dissemination of information on volcanic ash 

to aircraft. This information was included in SIGMETs and 

NOTAMs. This amendment was developed with the 

assistance of the former Volcanic Ash Warnings Study Group 

(VAWSG), which had been created in 1982. For the initial 

detection and notification of a volcanic eruption and/or 

volcanic ash cloud, ICAO sought and received the 

cooperation of a number of other international organizations 

that administer vulcanological observatories, aircraft reports 

and satellite data. The responsibility for the issuance of 

SIGMETs and NOTAMs lay with the meteorological watch 

offices (MWOs) and aeronautical control centres (ACCs) 

through their NOTAM Offices (NOFs), respectively, both of 

which are designated by States to provide service for a flight 

information region (FIR). 

 It was clear from the outset that many MWOs, not 

having necessary tools, would have difficulty in providing 

accurate forecasts of volcanic ash extent and trajectory for the 

SIGMET and particularly for the required twelve hours, i.e. 

six to eight hours beyond the usual period of validity of 

SIGMETs. Steps were taken by ICAO, therefore, to designate, 

on advice from WMO, centres having the capability to 

provide advisory information on volcanic ash to the MOWs. 

At the conjoint ICAO/WMO 

Communications/Meteorology/Operations (COM/MET/OPS) 

Divisional Meeting (1990), it was agreed that information on 

forecast trajectory covering 12 hours beyond the validity 

period of a SIGMET should be included in an “outlook”. 

Information to assist MWOs in preparing SIGMETs for 

volcanic ash, and especially the “outlook”, was to be provided 

by designated meteorological centres, which henceforth were 

known as volcanic ash advisory centres (VAACs). The 

designation of VAACs was accomplished one by one, as 

Provider States concerned agreed to accept the responsibility. 

The designations are reflected in the relevant ICAO regional 

air navigation plans. Due to the fact that the development of 

the IAVW involved coordination with other international 

organizations not hitherto linked to civil aviation, the 

operational procedures were largely based upon experience, 

and were tested as guidance material first before being 

included as formal ICAO Annex provisions. 

 Recent developments of the IAVW include the 

introduction of a new format for volcanic ash advisories and 

templates for SIGMETs for volcanic ash for data link 

purposes in 2001 (Appendix A). During the ICAO MET 

Divisional Meeting (2002), in order to face the problem of the 

lack of implementation (e.g. SIGMETs are not issued by 

certain States), a set of measures were recommended, 

including the review of the ICAO regional SIGMET guides. A 

requirement was also introduced for maintenance of a 24-hour 

watch by the VAACs. In view of flight safety considerations, 

the requirement for information from selected State volcano 

observatories was introduced in ICAO provisions in order for 

the ACCs MWOs and the VAACs to receive from these 

selected observatories messages on volcanic activity. All the 

provisions endorsed by the MET Divisional Meeting (2002) 

will become applicable in November 2004 as part of 

Amendment 73 to Annex 3. 

 In order to assist States exposed to volcanic 

eruptions, specific special implementation projects on the 

issuance of SIGMETs with emphasis on volcanic ash have 

been undertaken by ICAO in a number of ICAO Regions 

during recent years. Special implementation projects involved 

visits to States; in each State visited the ICAO expert met with 

officials from three areas involved in the implementation of 

the IAVW; ATS authorities/providers; 

MET authorities/providers and vulcanological agencies. In 

some of the States, representatives from the airlines were also 

available during the meetings. These projects were considered 

very successful by the States concerned and ICAO, and 

resulted in noticeable improvements in the local procedures. 

 The MET Divisional Meeting (2002), recognizing 

the need for a reliable operation of the IAVW and its impact 

in flight safety, recommended the establishment of an 

operations group in order to coordinate and oversee the 

development of the IAVW. In 2003, the International Airways 

Volcano Watch Operations Group (IAVWOPSG) was 

established; it held its first meeting in Bangkok, Thailand, in 

March 2004. It formulated twenty-eight conclusions and five 

decisions related to the operation and development of the 

IAVW. 

3. OPERATION OF THE IAVW 

 The IAVW comprises an observing part to detect 

volcanic eruptions and volcanic ash and a warning part 

concerned with the issuance of volcanic ash advisory 

information in both alphanumerical and graphical format, 

SIGMETs, NOTAMs (and the special series NOTAM called 

ASHTAM designed specifically for volcanic eruptions/ash). 

This section deals with the recent developments of the IAVW. 

3.1 Observing component of the IAVW 
Session 4 – Page 2 

 The observing part depends upon initial notification 

of volcanic eruptions/ash cloud to MWOs, ACCs and/or 

VAACs by vulcanological agencies, meteorological observing 

networks, United Nations Disaster Relief Organization field 

officers, national networks such as police, military, border 

guards, forestry personnel etc; pilot reports and satellite data. 

Substantial efforts have been made to ensure that personnel 

from the foregoing organized networks understand that if they 

see or learn of a volcanic eruption in their area they are to 

inform the nearest civil aviation or meteorological contact 

point. These contact points and channels of communication 

are organized nationally in those States having active 

volcanoes in the FIRs for which they are responsible. 

Ultimately, the notification of a volcanic eruption/ash cloud 

has to reach the ACCs, MWOs and VAACs to permit the 

issuance of the necessary advisory information, SIGMETs and 

NOTAMs. 

3.2 Ground-based observations 

 The ground-based observing part of the IAVW, 

which used to be dependent on voluntary cooperation, is by 

no means 100 per cent effective. In this regard, the MET 

Divisional Meeting (2002) was informed that difficulties were 

being experienced by some vulcanological agencies in 

obtaining the necessary funding for sending messages on 

volcanic activity to ACCs, MWOs and the VAACs in their 

region. These additional funds most often involved staffing 

and communications costs. In order to face this issue, the 

requirement for information from selected State volcano 

observatories is being introduced in ICAO provisions. This 

requirement means that the role of the volcano observatories, 

which are the front line of alert of the IAVW, will be 

formalized. 

3.3 Observations from air-reports 

 The provision of special air reports on volcanic 

eruptions/ash cloud by pilots is in general operating well, and 

on many occasions such reports have provided the initial 

notification of an eruption. However, at the IAVWOPSG/1 

Meeting it was recognized that there are still certain areas 

where further work is necessary. With regard to the 

implementation of the existing provisions concerning the 

reporting, recording and post-flight reporting of aircraft 

observations related to volcanic activity, there is a reluctance 

by some airlines in providing the special air report of volcanic 

activity form. According to the Procedures for Air Navigation 

Services — Air Traffic Management (PANSATM, Doc 4444), special air-reports containing volcanic 

activity shall be recorded on the special air-report on volcanic 

activity form. Information contained in this form is considered 

of particular importance to the successful operation of the 

VAACs due to the fact that the details related to the eruption 

can be deducted from the report. Therefore, the 

IAVWOPSG/1 concluded that airlines should be encouraged 

by ICAO to adhere to the existing provisions regarding the 

reporting, recording and post-flight reporting of aircraft 

observations of volcanic activity. 

3.4 Space-based observations 

 The space-based component using satellite data is 

critical for the VAACs in assessing the existence and extent of 

volcanic ash cloud, and in detecting the initial eruption. The 

space-based observations have the potential for the largest 

scope for improvement in the future. The MET Divisional 

Meeting (2002) had noted with satisfaction the work being 

done in some States in order to improve satellite-based 

techniques for the detection of volcanic eruptions and 

volcanic ash clouds. The additional capabilities that would 

assist future research offered by the second-generation of 

METEOSAT satellites launched by EUMETSAT was also 

noted. The MET Divisional Meeting (2002) called for WMO 

to encourage VAAC Provider States to continue and, if 

possible, to accelerate research on the detection of volcanic 

ash. During the Third International Workshop on Volcanic 

Ash (organized by Meteo-France in 2003, in cooperation with 

WMO and ICAO) the latest developments on the detection of 

volcanic eruptions and volcanic ash by remote sensing 

techniques were discussed. In this regard the METEOSAT 

second generation satellites and the potential use of the 

moderate resolution imaging spectroradiometer (MODIS) and 

the ground-based infrared detection (G-bIRD) were 

highlighted. During the same workshop all parties involved in 

the IAVW were encouraged to continue to develop modelling 

technologies with the enhancement of various models. 

3.2 Warning component of the IAVW 

3.2.1 Areas of responsibilities of the VAACs 

 Each Provider State of the VAACs undertook 

responsibility for an area for which they generally had access 

to high-resolution satellite information. There are some 

exceptions to this, but on the whole, this was the basic 

principle to which most Provider States adhered. For obvious 

reasons, the main international air routes were covered first 

which still left some areas of the world uncovered. In the 

evolving air navigation systems, the emphasis will be on 

“major traffic flows” from one “homogenous area” to another, 

and so-called “free flight”, which in theory, at least, will 

permit aircraft to flight plan off air routes for any flight level 

and routing which is considered economically attractive. It 

will be necessary, therefore, to ensure that the “major traffic 

flows” are adequately covered and eventually, most areas of 

the globe, in order to protect future “free flight” operations off 

air routes. In the actual concept of “organized tracks” the 

VAACs are providing adequate coverage, however, this may 

not be the case for the evolving ATM systems. In this regard, 

in response to a conclusion by the IAVWOPSG/1 Meeting, 

VAACs Toulouse and Washington agreed to extend their 

areas of responsibility in order for the IAVW to reach a quasiglobal coverage. The current VAAC areas of responsibility 

are given in Figure 1. 

3.2.2 Advisory information in graphical format 

 The alphanumerical and graphical formats for 

volcanic ash advisory information have existed for a few 

years. All VAACs issue volcanic ash advisory messages, but 

not all VAACs have implemented graphical advisories. The 

IAVWOPSG is currently developing a future format for 

graphical volcanic ash advisories to be issued by VAACs. The 

issuance of advisory messages in alphanumeric format 

continues to be essential for all VAACs because it provides a 

reliable means of addressing individual “offices or units” via 

the ICAO Aeronautical Fixed Telecommunication Network 
Session 4 – Page 3 

(AFTN); graphical advisories cannot be disseminated over the 

AFTN. Graphical advisories are disseminated on the 

International Satellite Communication System (ISCS) 1 and 2 

and the Satellite Distribution System for Information Relating 

to Air Navigation (SADIS) satellite broadcasts; however, their 

reception cannot be guaranteed. 

3.2.3 Distribution of NOTAMS for volcanic ash 

 The distribution of NOTAMs for volcanic ash and 

ASHTAMs on the SADIS and ISCS broadcasts, was tested in 

July 2001. The test was successful and proved that it is, in 

principle, possible to route these types of messages to SADIS 

provided that a WMO abbreviated header is added thereto. 

However, in an operational environment, adding such dummy 

headers is not feasible and the NOTAMs will have to be 

processed as they are. The IAVWOPSG had agreed that 

ASHTAMs and NOTAMs for volcanic ash be required for 

uplink on the ISCS and SADIS; and that a draft amendment to 

Annex 15 — Aeronautical Information Services be developed. 

3.2.4 Advisory information for airlines 

 Advisory information is also disseminated to 

airlines through an AFTN address provided specifically for 

this purpose. The introduction of this requirement was based 

on the fact that, in many cases, the first warning of the 

existence of an ash cloud came from the volcanic ash advisory 

message. 

4. EFFECTS OF RECENT VOLCANIC ERUPTIONS 

 There has been no respite in the recent past from the 

occurrence of violent volcanic eruptions producing ash cloud 

that warranted the issuance of advisories, SIGMETs and/or 

NOTAMs. Since the Pinatubo eruption in 1991, the 

volcanoes that have caused the most difficulty for civil 

aviation were probably Soufriere Hills in Montserrat, 

Popocatepetl and Colima in Mexico, Sakurajima and 

Suwanosejima in Japan, Etna in Italy, Tungurahua and El 

Reventador in Ecuador, Sheveluch, Karimsky, Klyuchevskoi, 

Cleveland and Anatahan in the North Pacific Ocean and 

Semeru, Ruang, Dukono and Ulawun in Indonesia, some of 

them continue to be active. There have, however, been 

numerous other eruptions that have caused temporary 

problems, especially over the North Pacific; and there have 

been few weeks when the IAVW has not been activated at 

least somewhere in the world. 

 In addition to its potential to cause a major aircraft 

accident, the consideration of the economic cost of volcanic 

ash to international civil aviation is staggering. This involves 

numerous complete engines changes, engine overhauls, 

different aircraft repairs, loss of revenue due to the aircraft 

down-time, cost of rerouting and delays, clearance from 

airports and damages to equipment and buildings on the 

ground. On average, various estimates made calculated the 

costs to aviation to be well in excess of US$ 250 million 

between 1982 and 2000. 

5. SPECIFIC PROBLEMS TO BE ADDRESSED 

 The following are the main issues, to be addressed 

within the IAVW: 

• lack of sufficiently reliable and timely notification 

of volcanic eruptions to ACCs, MWOs and 

VAACS; 

• communication difficulties between observing 

sources and ACCs, MWOs and VAACs and also 

between the ACCs/MWOs/VAACs themselves; and 

• extension of VAAC coverage over all future “major 

international air traffic flows” and, eventually, all 

areas to support “free flight” or “dynamic aircraft 

routing”. 

6. GUIDANCE MATERIAL 

 Extensive guidance has been prepared by ICAO to 

assist States and Users. Two documents were published by 

ICAO, in close cooperation with the IAVW, during the last 

few years. One is the Handbook on the International Airways 

Volcano Watch (IAVW) (Doc 9766) in 2000, updated in 2004, 

and the other is the Manual on Volcanic Ash, Radioactive 

Material and Toxic Chemical Clouds (Doc 9691) published in 

2001. 

 The handbook on the IAVW is an operational 

publication for the daily use by operational staff in the ACCs, 

NOFs, MWOs, VAACs and contains information regarding 

active volcanoes, VAACs and their responsibilities, useful 

websites, IAVW procedures and finally it provides the IAVW 

contact list. The handbook is available and kept up-to-date at 

the ICAO website: http://www.icao.int/anb/iavwopsg . 

 The main purpose of the manual is to assist States 

and international organizations involved in the IAVW by 

gathering together in one document information on the 

problem of volcanic ash, and to provide guidance regarding 

what each of the parties in the IAVW is expected to do and 

why. Currently ICAO, with the assistance of the 

IAVWOPSG, is in the process of updating the manual. It is 

expected that the new edition will be available in early 2005. 

 Additionally, ICAO produced training aids designed 

to support the implementation of the Standards and 

Recommended Practices (SARPs) related to volcanic ash. 

They consist of a video entitled Volcanic Ash Avoidance, and 

a poster entitled Warning — if you inadvertently enter a 

volcanic ash cloud. 

 Finally, as an example of excellent international 

cooperation, the World map of volcanoes and principal 

aeronautical features was issued in 1995. This world map was 

published by the USGS in a conjoint effort with Jeppesen 

Sanderson, Inc., ICAO, various US federal agencies, 

international organizations and individual experts involved in 

volcanic ash issues. 

7. FUTURE DEVELOPMENTS 

 The most urgent issue for the IAVW in the interest 

of air safety is how to ensure the reliable and timely 

notification of volcanic eruptions. In this regard, ICAO is 

working closely with WMO regarding the infrasonics and 

seismic network established by the Comprehensive Nuclear 

Test Ban Treaty Organization (CTBTO) to support the 

verification procedures. The idea is to study the feasibility by 
Session 4 – Page 4 

IAVW of gaining real-time access to the CTBTO infrasonic 

and seismic networks to detect volcanic eruption “signatures”. 

ICAO has been exchanging letters with the CTBTO 

Secretariat in this regard for the last year in support of the 

IAVW and in the interests of air safety. Currently the CTBTO 

is undertaking an assessment on the usefulness of seismic and 

infrasonic data from the CTBTO observing networks to the 

IAVW; it is expected that the final report will be sent to ICAO 

during the next few months. 

 Recently during a meeting of a working group of 

the WMO Commission of Basic Systems, it was indicated by 

the CTBTO that a potential existed as far as the use of the 

CTBTO network for IAVW was concerned; however, the 

results were preliminary with a number of unknowns. 

8. CLOSING REMARKS 

 It can be said that, given the safety and economic 

implications of volcanic ash to aircraft operations, it is 

necessary to maintain the IAVW in much the same way that 

the aerodrome fire services are maintained; in constant 

readiness but with the fervent hope that it rarely has to be 

used.
Session 4 – Page 5 

APPENDIX 5. TECHNICAL SPECIFICATIONS FOR SIGMET AND

AIRMET MESSAGES AND SPECIAL AIR-REPORTS

(See Chapter 7 of this Annex)

Table A5-1. Template for SIGMET and AIRMET messages and special air-reports

 Key: M = inclusion mandatory, part of every message

 C = inclusion conditional, included whenever applicable

 = = a double line indicates that the text following it should be placed on the subsequent line

Note.— The ranges and resolutions for the numerical elements included in SIGMET/AIRMET messages and 

in special air-reports are shown in Table A5-2 of this appendix.

Element as Template(s)

specified in 

Chapters 5 

and 7

Detailed 

content SIGMET SIGMET SST1 AIRMET SPECIAL AIRREPORT2

Examples

Location 

indicator of 

FIR/CTA 

(M)3

ICAO location 

indicator of the 

ATS unit 

serving the FIR 

or CTA to which 

the SIGMET/

AIRMET refers 

(M)

nnnn — YUCC4

YUDD4

Identification 

(M)

Message 

identification 

and sequence 

number5 (M)

SIGMET 

[nn]n

SIGMET SST 

[nn]n

AIRMET [nn]n ARS SIGMET 5

SIGMET A3

SIGMET SST 1

AIRMET 2

ARS

Validity 

period 

(M)

Date-time 

groups 

indicating the 

period of 

validity in UTC 

(M)

VALID nnnnnn/nnnnnn 6 VALID 

221215/221600

VALID 

101520/101800

VALID 

251600/252200

Location 

indicator of 

MWO (M)

Location 

indicator of 

MWO 

originating the 

message with a 

separating 

hyphen (M)

nnnn YUDO4

YUSO4

Name of the 

FIR/ CTA or

aircraft 

identification 

(M)

Name of the 

FIR/ CTA7 for 

which the 

SIGMET/AIRM

ET is issued or

aircraft 

radiotelephony 

call sign (M)

nnnnnnnnnn FIR[/UIR] or

nnnnnnnnnn CTA

nnnnnnnnnn 

FIR[/n]

nnnnnn AMSWELL FIR4

SHANLON FIR/UIR4

AMSWELL FIR/24

SHANLON FIR4

VA812

IF THE SIGMET IS TO BE CANCELLED SEE FOR DETAILS AT THE END OF THE TEMPLATE 

Phenomenon 

(M)8

Description of 

phenomenon 

causing the 

issuance of 

SIGMET/AIRM

ET (C)

OBSC9 TS 

[GR10]

EMBD12 

TS [GR]

FRQ13 TS 

[GR]

SQL14 TS 

[GR]

MOD TURB11 

SEV TURB

ISOL15 CB16

OCNL18 CB

FRQ13 CB

GR

SFC WSPD nn[n]KMH 

(SFC WSPD nn[n]KT)

SFC VIS nnnnM (nn)17

ISOL15 TS[GR]10

OCNL18 TS[GR]

MT OBSC

TS

TSGR

SEV 

TURB

SEV ICE

SEV 

MTW

SEV TURB

FRQ TS

OBSC TS GR

EMD TS GR

TC GLORIA

VA ERUPTION MT 

ASHVAL LOC S15

E073 VA CLD
Session 4 – Page 6 

TC 

nnnnnnnnn

n

SEV 

TURB11

SEV ICE19

SEV ICE 

(FZRA)20

SEV 

MTW21

HVY DS

HVY SS

VA[ERUPTI

ON] [MT 

nnnnnnnnn

n] [LOC

Nnn[nn] or 

Snn[nn]

Ennn[nn] or 

Wnnn[nn]] 

VA CLD

VA[ERUPTION] 

[MT 

nnnnnnnnnn] 

[LOC

Nnn[nn] or 

Snn[nn]

Ennn[nn] or 

Wnnn[nn]] VA 

CLD

BKN CLD

nnn/[ABV]nnnnM

(BKN CLD

nnn/[ABV]nnnnFT)

OVC CLD

nnn/[ABV]nnnnM

(OVC CLD

nnn/[ABV]nnnnFT)

ISOL15 CB16

OCNL18 CB

FRQ13 CB

ISOL15 TCU16

OCNL18 TCU16

FRQ13 TCU

MOD TURB11

MOD ICE19

MOD MTW21

HVY SS

VA CLD 

[FL 

nnn/nnn]

VA [MT 

nnnnnnn

nnn]

MOD 

TURB11

GR10

CB16

MOD TURB

MOD MTW

ISOL CB

BKN CLD 120/900M

(BKN CLD

400/3000FT)

OVC CLD

270/ABV3000M

(OVC CLD

900/ABV10000FT)

SEV ICE

OBS AT 

nnnnZ

Observed or 

forecast 

phenomenon 

(M)

Indication 

whether the 

information is 

observed and 

expected to 

continue, or

forecast (M)

OBS [AT nnnnZ]

FCST

OBS [AT nnnnZ] AND FCST 

—

OBS AT 1210Z

OBS

OBS AND FCST

OBS AT 2245Z

Location (C) Location 

(referring to 

latitude and 

longitude (in 

degrees and 

minutes) or

locations or 

geographic 

features well 

known 

internationally) 

[N OF, NE OF, E OF, SE OF, S OF, SW OF, W OF, 

NW OF] 

[Nnn[nn]][Wnnn[nn]] or

[N OF, NE OF, E OF, SE OF, S OF, SW OF, W OF, 

NW OF] 

[Nnn[nn]][Ennn[nn]] or

[N OF, NE OF, E OF, SE OF, S OF, SW OF, W OF, 

NW OF] 

[Snn[nn]][Wnnn[nn]] or

[N OF, NE OF, E OF, SE OF, S OF, SW OF, W OF, 

NW OF] 

[Snn[nn]][Ennn[nn]] or

[N OF, NE OF, E OF, SE OF, S OF, SW OF, W OF, 

NW OF] 

nnnnnnnnnnnn

NnnnnW

nnnnn or

NnnnnW

nnnnn or

SnnnnW

nnnnn or

SnnnnEn

nnnn

S OF N54

N OF N50

N2020 W07005

YUSB4

N2706 W07306

N48 E010

Level (C) Flight level 

and

extent22(C)

FLnnn or FLnnn/nnn or TOP FLnnn or [TOP] ABV 

FLnnn or[TOP] BLW FLnnn 

or23

CB TOP [ABV] FLnnn WI nnnKM OF CENTRE 

(CB TOP [ABV] FLnnn WI nnnNM OF CENTRE) or

CB TOP [BLW] FLnnn WI nnnKM OF CENTRE 

(CB TOP [BLW] FLnnn WI nnnNM OF CENTRE) 

or24

FLnnn/nnn [APRX nnnKM BY nnnKM]

[Nnn[nn] or Snn[nn]Wnnn[nn] or Ennn[nn] 

TO Nnn[nn] or Snn[nn]Wnnn[nn] or Ennn[nn]

[TO Nnn[nn] or Snn[nn]Wnnn[nn] or Ennn[nn]]

[TO Nnn[nn] or Snn[nn]Wnnn[nn] or Ennn[nn]]

(FLnnn/nnn [APRX nnnNM BY nnnNM]

[Nnn[nn] or Snn[nn]Wnnn[nn] or Ennn[nn] 

TO Nnn[nn] or Snn[nn]Wnnn[nn] or Ennn[nn]

[TO Nnn[nn] or Snn[nn]Wnnn[nn] or Ennn[nn]]

[TO Nnn[nn] or Snn[nn]Wnnn[nn] or Ennn[nn]]) 

FLnnn FL180

FL050/080

TOP FL390

BLW FL200

TOP ABV FL100

FL310/450

CB TOP FL500 WI 

270KM OF CENTRE

(CB TOP FL500 WI 

150NM OF 

CENTRE)

FL310/350 APRX 

220KM BY 35KM

FL390
Session 4 – Page 7 

Movement or 

expected 

movement 

(C)

Movement or 

expected 

movement with 

reference to 

one of the eight 

points of 

compass, or 

stationary (C)

MOV N [nnKMH] or MOV NE [nnKMH] or MOV E 

[nnKMH] or 

MOV SE [nnKMH] or MOV S [nnKMH] or MOV SW 

[nnKMH] or 

MOV W [nnKMH] or MOVNW[nnKMH] or

(MOV N [nnKT] or MOV NE [nnKT] or MOV E [nnKT] or 

MOV SE [nnKT] or MOVS[nnKT] or MOV SW [nnKT] or

MOV W [nnKT] or MOV NW [nnKT]) or

STNR 

 — MOV E 40KMH

(MOV E 20KT)

MOV SE

STNR

Changes in 

intensity (C)

Expected 

changes in 

intensity (C)

INTSF or WKN or NC — WKN

Forecast 

position 

(C)22

Forecast 

position of 

volcanic ash 

cloud or the 

centre of the 

TC at the end 

of the validity 

period of the 

SIGMET

message (C)

FCST nnnnZ TC CENTRE

Nnn[nn] or Snn[nn]Wnnn[nn] or Ennn[nn] 

or

FCST nnnnZ VA CLD 

Nnn[nn] or Snn[nn]Wnnn[nn] or Ennn[nn]

TO Nnn[nn] or Snn[nn]Wnnn[nn] or Ennn[nn] 

[TO Nnn[nn] or Snn[nn]Wnnn[nn] or Ennn[nn]]

[TO Nnn[nn] or Snn[nn]Wnnn[nn] or Ennn[nn]] 

— — FCST 2200Z TC 

CENTRE N2740 

W07345

FCST 1700Z VA 

CLD S15 E075 TO 

S15 E081 TO S17 

E083 TO S18 E079 

TO S15 E75

Outlook22 

(C)

Outlook 

providing 

information 

beyond the 

period of 

validity of the 

trajectory of the 

volcanic ash 

cloud and 

positions of the 

tropical cyclone 

centre (C)

OTLK nnnnnn TC CENTRE

Nnnnn or SnnnnWnnnnn or Ennnnn

nnnnnn TC CENTRE 

Nnnnn or SnnnnWnnnnn or Ennnnn

or

OTLK nnnnn VA CLD APRX

[Flnnn/nnn]25 Nnn[nn] or Snn[nn] Wnnn[nn] or

Ennn[nn] 

TO Nnn[nn] or Snn[nn]Wnnn[nn] or Ennn[nn] 

TO Nnn[nn] or Snn[nn]Wnnn[nn] or Ennn[nn] 

[TO Nnn[nn] or Snn[nn]Wnnn[nn] or Ennn[nn]]

[TO Nnn[nn] or Snn[nn]Wnnn[nn] or Ennn[nn]]

nnnnnn VA CLD APRX

Nnn[nn] or Snn[nn]Wnnn[nn] or Ennn[nn] 

TO Nnn[nn] or Snn[nn]Wnnn[nn] or Ennn[nn] 

TO Nnn[nn] or Snn[nn]Wnnn[nn] or Ennn[nn] 

[TO Nnn[nn] or Snn[nn]Wnnn[nn] or Ennn[nn]]

[TO Nnn[nn] or Snn[nn]Wnnn[nn] or Ennn[nn]]

OTLK 260400 TC 

CENTRE N28030 

W07430 261000 TC 

CENTRE N3100 

W07600

OTLK 212300 VA 

CLD APRX S16 

E078 TO S17 E084 

TO S18 E089 TO 

S19 E081 TO S16 

E078 220300 VA 

CLD APRX S17 E81 

TO S18 E86 TO S20 

E92 TO S21 E84 TO 

S17 E81

OR 

Cancellation 

of SIGMET/

AIRMET26 

(C)

Cancellation of 

SIGMET/AIRM

ET referring to 

its identification

CNL SIGMET 

[nn]n 

nnnnnn/nnnnnn

CNL SIGMET 

SST [nn]n 

nnnnnn/nnnnn

n

CNL AIRMET [nn]n 

nnnnnn/nnnnnn

— CNL SIGMET 2 

101200/10160026

CNL SIGMET SST 1 

212330/22013026

CNL AIRMET 

151520/ 15180026

Notes.–

1. Only for transonic and supersonic flights.

2. Automated special air-reports also include information on wind and temperature which does not need to be uplinked to 

other aircraft in flight.

3. In cases where the airspace is divided into a flight information region (FIR) and an upper flight information region 

(UIR), the SIGMET is identified by the location indicator of the air traffic services unit serving the FIR; nevertheless, the 

SIGMET message applies to the whole airspace within the lateral limits of the FIR, i.e. to the FIR and to the UIR. The 

particular areas and/or flight levels affected by the meteorological phenomena causing the issuance of the SIGMET are 

given in the text of the message.

4. Fictitious location.

5. Corresponding with the number of SIGMET/AIRMET messages issued for the FIR/CTA since 0001 UTC on the day 

concerned.

6. Special air-reports are to be uplinked for 60 minutes after their issuance.

7. Or a sub-area thereof in the case of AIRMET messages.

8. Only one of the weather phenomena listed should be selected and included in each SIGMET.
Session 4 – Page 8 

9. Obscured (OBSC) indicates that the thunderstorm (including, if necessary, cumulonimbus cloud which is not 

accompanied by a thunderstorm) is obscured by haze or smoke or cannot be readily seen due to darkness.

10. Hail (GR) may be used as a further description of the thunderstorm as necessary.

11. Severe and moderate turbulence (TURB) refers only to: low-level turbulence associated with strong surface winds; 

rotor streaming; or turbulence whether in cloud or not in cloud (CAT) near to jet streams. Turbulence is not required to be 

used in connection with convective clouds. Turbulence is considered:

 a) severe whenever the turbulence index is between 15 and 27 (i.e. the peak value of the eddy dissipation rate (EDR) 

exceeds 0.5); and

 b) moderate whenever the turbulence index is between 6 and 14 (i.e. the peak value of the eddy dissipation rate 

(EDR) exceeds 0.3 while not exceeding 0.5).

12. Embedded (EMBD) indicates that the thunderstorm (including cumulonimbus cloud which is not accompanied by a 

thunderstorm) is embedded within cloud layers and cannot be readily recognized.

13. Frequent (FRQ) indicates an area of thunderstorms within which there is little or no separation between adjacent 

thunderstorms with a maximum spatial coverage greater than 75 per cent of the area affected, or forecast to be affected, 

by the phenomenon (at a fixed time or during the period of validity).

14. Squall line (SQL) indicates thunderstorm along a line with little or no space between individual clouds.

15. Isolated (ISOL) indicates an area of individual cumulonimbus and/or thunderstorms with a maximum spatial coverage 

less than 50 per cent of the area affected, or forecast to be affected, by the phenomenon (at a fixed time or during the 

period of validity).

16. The use of cumulonimbus, CB, is restricted to AIRMETs and SIGMETs related to SST flight during transonic and 

supersonic cruise; the use of towering cumulus, TCU, is restricted to AIRMETs.

17. The weather phenomenon causing the reduction in visibility in brackets; choose one from the following list: DZ, RA, 

SN, SG, PL, IC, GR, GS, FG, BR, SA, DU, HZ, FU, VA, PO, SQ, FC, DS or SS.

18. Occasional (OCNL) indicates an area of well-separated cumulonimbus and/or thunderstorms with a maximum spatial 

coverage between 50 and 75 per cent of the area affected, or forecast to be affected, by the phenomenon (at a fixed time 

or during the period of validity).

19. Severe and moderate icing (ICE) refers to severe icing in other than convective clouds.

20. Freezing rain (FZRA) refers to severe icing conditions caused by freezing rain.

21. A mountain wave (MTW) is considered:

 a) severe whenever an accompanying downdraft of 3.0 m/s (600 ft/min) or more and/or severe turbulence is observed 

or forecast;

 b) moderate whenever an accompanying downdraft of 1.75–3.0 m/s (350–600 ft/min) and/or moderate turbulence is

observed or forecast.

22 Only for SIGMET messages for volcanic ash cloud and tropical cyclones.

23. Only for SIGMET messages for tropical cyclones.

24. Only for SIGMET messages for volcanic ash.

25. Up to four layers (or levels) to be included in the SIGMET outlook for volcanic ash.

26. End of the message (as the SIGMET/AIRMET message is being cancelled).

General Note.— Severe or moderate icing and severe or moderate turbulence (SEV ICE, MOD ICE, SEV TURB, MOD 

TURB) associated with thunderstorms, cumulonimbus clouds or tropical cyclones should not be included.
Session 4 – Page 9 

ADVISORY MESSAGE FOR VA

VOLCANIC ASH ADVISORY

ISSUED: 20000402/0700Z

VAAC: TOKYO

VOLCANO: USUZAN 805-03

LOCATION: N4230E14048

AREA: JAPAN

SUMMIT ELEVATION: 732M

ADVISORY NUMBER: 2000/432

INFORMATION SOURCE: GMS JMA

AVIATION COLOUR CODE: RED

ERUPTION DETAILS: ERUPTED 20000402/0614Z ERUPTION OBS ASH TO ABV FL300

OBS ASH DATE/TIME: 02/0645Z

OBS ASH CLD: FL150/350 N4230E14048-N4300E14130-N4246E14230-N4232E14150-N4230E14048 

SFC/FL150 MOV NE 25KT FL150/350 MOV E 30KT 

FCST ASH CLD + 6 HR: 02/1245Z SFC/FL200 N4230E14048-N4232E14150-N4238E14300-N4246 E14230 

FL200/350 N4230E14048-N4232E14150N4238E14300-N4246E14230 

FL350/600 NO ASH EXP

FCST ASH CLD + 12 HR: 02/1845Z SFC/FL300 N4230E14048-N4232E14150-N4238E14300-

N4246E14230 FL300/600 NO ASH EXP

FCST ASH CLD + 18 HR: 03/0045Z SFC/FL600 NO ASH EXP

NEXT ADVISORY: 20000402/1300Z

REMARKS: ASH CLD CAN NO LONGER BE DETECTED ON SATELLITE IMAGE

SIGMET FOR VA

YUDD SIGMET 2 VALID 211100/211700 YUSOSHANLON FIR/UIR VA ERUPTION MT ASHVAL LOC E S1500 E07348 VA CLD OBS AT 1100Z 

FL310/450 APRX 220KM BY 35KM S1500 E07348E TO S1530 E07642 MOV ESE 65KMH FCST 1700Z VA 

CLD APRX S1506 E07500 TO S1518 E08112 TO S1712 E08330 TO S1824 E07836 

OTLK 212300Z VA CLD APRX S1600 E07806 TO S1642 E08412 TO S1824 E08900 TO S1906 E08100 

220500Z VA CLD APRX S1700 E08100 TO S1812 E08636 TO S2000 E09224 TO S2130 E08418
Session 4 – Page 10 

FIGURE 1
4.2 

Session 4 – Page 11 

THE WORLD METEOROLOGICAL ORGANIZATION (WMO) ACTIVITIES 

RELATED TO VOLCANIC ASH 

 

Mr. Saad Benarafa, World Meteorological Organization, 

Geneva, Switzerland 

ABSTRACT 

This paper provides the main thrusts of the World Meteorological Organization (WMO) activities 

related to volcanic ash. The WMO Emergency Response Activities (ERA) Programme objectives are 

presented and the involvement of the WMO designated Regional Specialized Meteorological Centers 

(RSMCs) is highlighted. The excellent cooperation with the International Civil Aviation Organization 

(ICAO) regarding the international airways volcano watch is also highlighted 

The World Meteorological Organization (WMO) 

is one of the various stakeholders involved in 

volcanic ash and aviation safety. The WMO 

Emergency Response Activities (ERA) 

Programme is being implemented to assist 

National Meteorological and Hydrological 

Services (NMHSs), other relevant agencies of 

WMO Member countries and international 

organizations to respond effectively to 

environmental emergencies related to large-scale 

transboundary air pollution, caused in particular 

by major nuclear accidents, volcanic eruptions, 

and land fires. This programme is implemented 

through the provision of specialized Global Data 

Processing and Forecasting System products by 

29 designated WMO Regional Specialized 

Meteorological Centers (RSMCs). This 

programme also includes the development and 

implementation of procedures for the provision 

and exchange of specific observational data, and 

related training support for users. The WMO 

Fourteenth Congress (Cg-XIV) held in May 

2003, decided to expand the ERA Programme to 

include, in particular, chemical accidents.

Through the ERA Programme under the 

auspices of the World Weather Watch and the 

Global Atmospheric Watch Programme (GAW) 

being implemented under the Atmospheric 

Research and Environment Programme (AREP), 

WMO will continue to support its Members to 

develop the appropriate environmental 

prediction tools to prepare and strengthen their 

capability to advise Member countries relevant 

national authorities when required. In this regard 

, the “ensemble” approach for predicting the 

atmospheric transport and dispersion of tracers is 

being explored for emergency response 

applications and WMO constituent bodies are 

encouraging RSMCs to further develop and test 

new technologies such as ensemble methods, 

new products to satisfy growing requirements 

and the use of the Internet for the information 

exchange.

In line with its excellent cooperation 

with ICAO regarding aviation safety, WMO has 

been actively participating in activities 

undertaken by the ICAO International Airways 

Volcano Watch Operations Group 

(IAVWOPSG). In this context, ICAO has been 

benefiting from results of the specialized 

atmospheric transport modeling of airborne 

volcanic ash conducted under WMO auspices. 

Products generated from transport models are 

essential for supporting the operations of the 

International Airways Volcano Watch 

Programme 

In response to Recommendation 1/18 of 

the Conjoint WMO CAeM 

Session/ICAO/Meteorology Divisional Meeting 

(2002), related to the completion of the 

assessment of the usefulness of seismic and 

infrasonic data from the Comprehensive Test 

Ban Treaty Organization (CTBTO) monitoring 

networks detecting explosive volcanic eruptions, 

a report on this assessment, that will not include 
Session 4 – Page 12 

a definitive conclusion, is expected to be sent by 

CTBTO to ICAO and WMO in the near future. 

If the assessment concludes that the provision of 

CTBT data is of use to the IAVW and thus 

worth implementing operationally, it would be 

necessary to prepare a “road map”, which would 

lead to the implementation of operational 

arrangements between CTBTO, ICAO and 

WMO. 
4.3 

Session 4 – Page 13 

NOAA’S NWS VOLCANIC ASH PROGRAM: CURRENT STATUS AND PLANS FOR THE 

FUTURE 

Christopher S. Strager, NWS Alaska Region Headquarters, Anchorage, AK, USA 

Jeffrey M. Osiensky, NWS Alaska Aviation Weather Unit, Anchorage AK, USA 

Gary L. Hufford, NWS Alaska Region Headquarters, Anchorage, AK, USA 

Operationally, the National Oceanic and Atmospheric Administration (NOAA) plays an important role in 

the worldwide volcanic ash network through the operation of two of the world’s nine Volcanic Ash 

Advisory Centers (VAACs) and four Meteorological Watch Offices (MWO). The operational 

responsibilities of these two VAACs are defined in the International Civil Aviation Organization (ICAO) 

Annex 3. The Washington VAAC is jointly managed by the National Environmental Satellite, Data and 

Information Service (NESDIS) Satellite Analysis Branch and the National Weather Service’s (NWS) 

National Centers for Environmental Prediction (NCEP). The Anchorage VAAC is managed by the NWS’ 

Alaska Aviation Weather Unit. Together, these centers are responsible for providing volcanic ash 

advisories and ash dispersion forecasts for a wide area ranging from the Pacific Ocean eastward over the 

U.S and much of the Atlantic Ocean. Research and development efforts in support of those operations 

include (but are not limited to) assets from NOAA’s NCEP, NESDIS, Forecast Systems Laboratory, Air 

Research Laboratory and U.S. Geological Survey. With regards to policy, NOAA’s Volcanic Ash 

Program has a responsibility to meet both U.S. and international customers’ needs by ensuring product 

content, dissemination and coordination procedures remain consistent and compatible with ICAO 

standards. This presentation will examine NOAA’s NWS Volcanic Ash Program, discussing the current 

status and future plans in the areas of operations, research/development, and policy development. 
4.4 

Session 4 – Page 15 

VOLCANIC ASH IMPACT ON INTERNATIONAL AIRPORT 

OF MEXICO CITY (AICM), DUE TO EMISSIONS 

OF POPOCATEPETL VOLCANO 

Humberto Rodríguez, DMTA of SENEAM, México, D. F. México. 

ABSTRACT 

Since 1995, the CAPMA of SENEAM, which is the main office of the Aviation Weather Service in 

Mexico, has been issued SIGMETS of volcanic ash. At present, most of the SIGMETS were issued 

due to emissions of Popocatepetl volcano. Since that time Popocatepetl volcano has had several 

erupted events some of them have threatened the safety of the aviation . In this work we are going to 

comment two important eruptions: (1) The event occurred on June 30, 1997, where the AICM was 

closed for about 10 hours and (2) The July 19, 2003 event. The collaboration from VAAC of 

Washington, CENAPRED in Mexico City and The Air Traffic Service (ATS) of SENEAM has been 

essential to alert the pilots and flight dispatchers about volcanic ash plumes. However, we still have 

lack of tools and techniques to track more efficiently the volcanic ash plumes. 

INTRODUCTION 

Since December 21, 1994, Popocatepetl volcano 

started another eruptive stage. This obligated 

authorities of Civil Aviation, AICM (Aeropuerto 

Internacional de la Ciudad de Mexico - International 

Airport of Mexico City), and SENEAM (Servicios a 

la Navegación en el Espacio Aéreo Mexicano), 

among others entities, to restrict flight operations 

around 10 NM from volcano crater. Also, a 

contingency plan was issued to prevent and minimize 

the threat of volcanic ash plumes. The CAPMA 

(Centro de Análisis y Pronósticos Meteorológicos 

Aeronáuticos - Analysis and Forecasting 

Meteorological Center for Aviation) of SENEAM, 

which is the main meteorological office of the 

Aviation Weather Service in Mexico was designated 

the responsible to gather information of volcanic 

activity an also responsible to issue the volcanic ash 

SIGMETS. The CAPMA receives information and 

reports from CENAPRED (Centro Nacional de 

Prevención de Desastres - National Center for 

Disaster Prevention), Weather Observers, Controllers, 

Pilots, Civil Protection and VAAC of Washington. 

The coordination between the VAAC of Washington 

and CAPMA is so important and it has been improved 

since we had the June 30, 1997 event. CAPMA of 

SENEAM has a procedure, which is followed 

carefully when a volcanic ash plume is reported. This 

is important because we can alert with more 

opportunity to airlines and pilots. In this work we try 

to discuss two cases related with volcanic ash that 

have impacted the AICM and emphasize the roll of 

aeronautic meteorology in the prevention of these 

phenomena. Also, to show the economic impact they 

caused to aeronautical operations in Mexico. 

POPOCATEPETL VOLCANO FEATURES 

• It is located about 35NM (64.8km) southeast 

of International Airport of Mexico City. See 

Fig. 1. 

• It has an age of 700,000 years (CENAPRED, 

1995) 

• Its geographical position is: 19.0°N and 

98.6oW 

• Popocatepetl means “Smoking Mountain” 

• Elevation: 5,465 m (17,930 ft ). 

 

 

Fig. 1: Location of Popocatepetl volcano (source: 

CENAPRED). 
Session 4 – Page 16 

AICM FEATURES 

• About 830 operations take place daily. 

• In 2003 about 21 million passengers used the 

AICM. 

• It is located in the Northeast Mexico City 

area, at 35NM northwest of Popocatepetl 

volcano. 

• Elevation: 2,229m (7,316 ft ). 

• Geographical location: 19°25’N and 

99°05’W. 

THE JUNE 30, 1997 CASE 

Popocatepetl volcano is so close to Mexico City and 

consequently close to the “Benito Juarez” 

International Airport of Mexico City (AICM). This 

means the constant threat of volcanic ash plumes 

due to summer circulation which has a 

East/Southeast (E/SE) wind component in the low 

and middle levels of the atmosphere, between May 

to October months of each year. 

There are no records in the history of AICM that 

indicate the volcanic ash has impacted the Airport of 

Mexico City like the case we are going to discuss. As 

we pointed before, Popocatepetl volcano started with 

some important activity at the end of 1994. During 

the years of 1995 to 1996 occurred some considerable 

eruptions. However, in the evening of June 30, 1997 

a big one was present. At 19:26 hrs. LT (0026 UTC), 

the crew of AVIACSA airline reported that a large 

volcanic ash plume from Popocatepetl was moving to 

Mexico City. This was the first report received in the 

CAPMA of SENEAM. Few minutes later, at 19:30 

hrs. LT (0030 UTC), a report from CENAPRED, 

confirmed the eruption indicating the ash column 

reached, in few minutes, a high of 8km from volcano 

crater (De la Cruz-Reyna and Quaas, 1997). That 

means the ash column reached an altitude of more 

than 40,000 ft. 

According to sounding of Mexico City of July 01, 

1997 at 0000 UTC, at middle levels we had winds 

with a component of the east with 20knots (kt), 

meanwhile in upper levels (25,000 to 40,000 ft), the 

winds had a direction from southeast with an 

intensity of 15 kt. This sounding showed a deep layer 

of 7km of moisture (around 4.7km thickness). The 

weather reports (METAR) from AICM indicated a 

ceiling conditions of broken of low clouds, overcast 

of middle clouds and light rain. These weather 

conditions presented to observers a difficulty to 

evaluate what was going on that evening. On the 

other hand, the convective clouds covering 

Popocatepetl volcano did not allow us to observe the 

ash plume in the GOES-8 satellite infrared imagery. 

The ash started to fall around 0110 UTC over the 

AICM and ending at 0645 UTC. We recognize that 

this surprised event caused some confusing among 

the personal who work at the AICM because it was 

the first time we had an event like this. The Local 

Security committee of AICM determined to close 

the airport at 21:20 hrs. LT (0220 UTC). 

The Air Traffic Services of SENEAM prepared 10 

airports as alternative airports to receive the deflected 

flights. The AICM was closed for about 10 hours. 

At 07:13 hrs. LT (1213 UTC) of July 1, 1997 the 

International Airport of Mexico City started 

operations using the 05R runway. To clean up the 

runways was a difficult mater, we had to use brooms 

to sweep the dust and particles of volcanic ash from 

the runways surface. The aeronautical operations of 

AICM were recovering gradually. At 16:13 hrs LT 

(2113 UTC), the runway 05L was opened to air traffic 

(DGAC, 1997). 

This event caused a lot of damage and losses to 

aeronautical industry in Mexico. Table 1, shows us 

the economic impact that emissions of Popocatepetl 

volcano caused on June 30, 1997. The experience left 

by this eruption was taking into account and it has 

allowed us to improve our contingency plans in order 

to face with more efficiency episodes like these, that 

can happen again at any time. 

Table 1: Economic Impact at AICM, June 30, 1997. 

CONCEPT AMOUNT LOSSES 

($USD) 

WINDSHIELD 

DAMAGED 

22 132,000.00 

ENGINE 

DAMAGED 

3 2,588,417.00 

PASSENGERS 

AFFECTED 

19, 000 

DELAYS 15,957 

minutes 

515,781.00 

LOSSES DUE TO 

AFFECTED 

PASSENGERS 

 588,643.00 

AIRLINE LOSSES 1,351,994.00 

CANCELED 

FLIGHTS 

205 

DELAY FLIGHTS 284 

DEFLECTED 

FLIGHTS 

19 

AIRPORT CLOSED 10 HRS. 

Source: DGAC, SCT, 1997. 

THE JULY 19, 2003 CASE 

In this case, as the previous one, the trade winds were 

the cause of volcanic ash plume moves to Mexico 

City. That day of July 19, 2003, CENAPRED 

reported the event started at 09:20 hrs LT (1420 UTC) 

with a dense volcanic ash column which reached an 

altitude of more than 28,000 ft (CENAPRED, 2003). 
Session 4 – Page 17 

The sounding of Mexico City (MEX) of July 19, 2003 

at 1200 UTC, showed a wind profile with an east 

component almost in all levels with 10 to 15 kt speed. 

Because of this circulation the ash plume was forced 

to move to central and south areas of Mexico City. 

Fortunately, with this situation the AICM was less 

affected than the event of June 30, 1997. This pattern 

of wind was determinant to carry out the volcanic ash, 

mainly to Mexico City. The volcanic ash arrived 

AICM at 13:25hrs. LT (1825UTC). In other scenery, 

with a wind pattern like shown by the sounding of 

MEX at 1200Z of July 20, 2003, the impact on 

AICM had been devastate due to the wind direction, 

it was from the southeast, in the middle and upper 

levels of the atmosphere, with an intensity of 15kt. 

Fortunately this circulation occurred the next day of 

the event, so that, no ash emission occurred 

The weather observations (METAR) of MEX 

reported, almost for five hours, from 191825Z to 

192203Z, light volcanic ash fallen on AICM. Even 

with this condition, the visibility was ranging 

between 5 to 6 statute miles. Also, these weather 

reports indicated the ash plume was moving 

westward . In comparison with the June 1997 case, 

in this event the AICM was working nearly in normal 

conditions. The International Airport of Mexico City 

was closed only for 6 minutes, between 191832Z to 

191838Z (ATS of SENEAM records, 2003). The 

airline with more delays was AEROMAR (Lydia 

Robles, 2004, personal communication). Table 2 

shows the economic impact caused by the eruption 

of Popocatepetl volcano. No damage to windshield 

and engine of aircrafts were reported. 

Table 2: Economic impact at AICM, July 19, 2003. 

CONCEPT AMOUNT LOSSES 

($USD) 

PASSENGERS 

AFFECTED 

380 

DELAYS 70 minutes 

AIRLINE LOSSES 19,250.00 

CANCELED 

FLIGHTS 

1 

DELAY FLIGHTS 2 

AIRPORT CLOSED 6 minutes 

Source: Airlines and ATS of SENEAM, 2004 

CONCLUSIONS 

We have learned a lot from the experiences left by 

these two cases. After this events we have to improve 

and verify our procedures and contingency plans to 

prevent as possible, the threat and effects of volcanic 

ash plumes. Some of the most important conclusions 

are pointed below: 

• The aviation safety must be our first priority. 

• Alert Pilots and Airlines, as soon as possible, 

about volcanic ash plumes to mitigate negative 

impacts like those discussed here. 

• The communication and coordination between 

CAPMA and VAAC of Washington, 

CENAPRED, ATS, and DGAC have been 

improved significantly, since the June 30, 1997 

event. 

• Maintain a permanent volcano watch. 

• Improve our contingency plans. 

• Continuos training for operational 

meteorologists. 

• The need of appropriate equipment such as: 

Wind profiler, Doppler Weather Radar, Software 

to analyze satellite data, etc. 

ACKNOWLEDGMENTS 

I would like to thank the USGS, NOAA, OFCM 

among others entities for their support to participate 

in the 2nd. International Conference on Volcanic Ash 

and Aviation Safety. Also, to thanks Authorities of 

SENEAM who gave me the permission to attend this 

important meeting. And finally, thanks to Grace 

Swanson, from VAAC of Washington, who is the 

person we have received a great collaboration in this 

matter. 

REFERENCES 

CENAPRED, 1995, 2003, SG. 

De la Cruz-Reyna, Servando y Roberto Quaas, 1997: 

Resumen de la Erupción del Volcán 

Popocatepetl del día 30 de Junio de 1997. 

CENAPRED, Agosto de 1997. 

DGAC, SCT Informe, 1997: Volcán Popocatepetl. 

Robles, Lydia. 2004, Personal communication, 

Aeromar. 

SENEAM, ATS records, Julio 19, 2003, ACC MEX.. 
4.5 

Session 4 – Page 19 

THE DARWIN VAAC VOLCANIC ASH WORKSTATION 

Rodney Potts1

, Mey Manickam1, Andrew Tupper2 and Jason Davey2

1

 Bureau of Meteorology Research Centre, Melbourne, Australia 

2

 Bureau of Meteorology, Darwin Regional Office, Australia 

Introduction 

The Darwin VAAC has been operating since March 

1993 providing advice on volcanic ash for the aviation 

industry in accordance with arrangements established as 

part of the ICAO IAVW (ICAO, 2001). The Volcanic 

Ash Advisories (VAA’s) are based on an initial report 

of an eruption, an analysis of satellite data to identify 

and track the ash cloud, and a forecast of the movement 

of the ash derived from upper level winds and an 

atmospheric dispersion model. The VAA message is 

prepared in the agreed format and disseminated to the 

aviation industry. This process must be completed in a 

timely manner so that aircraft likely to be affected by 

the ash cloud can take appropriate avoidance measures. 

There are a number of complex issues in the preparation 

of warnings relating to volcanic ash. There are 

numerous volcanoes in the Darwin area of responsibility 

and most are remote and not routinely monitored. As a 

result, advice of volcanic eruptions or ash clouds may 

be delayed. Current satellite data has proved of 

considerable value for detection of volcanic eruptions 

and the detection and tracking of ash clouds and there 

have been improvements in the utilisation of these data 

to support the volcanic ash warning service. However, 

the discrimination of volcanic ash from water/ ice 

clouds and delineation of the observed ash boundary 

remains problematic with current data and processing 

techniques. This necessitates intensive manual analyses 

of satellite data with resultant time and resource 

implications. Ash dispersion models provide useful 

guidance on the expected movement of an ash cloud but 

there are uncertainties in the wind field in the 

underlying atmospheric model and the source term for 

initialising the dispersion model. Moreover, the 

concentration of ash that presents a risk to aircraft, 

either for safety reasons or maintenance impacts, is not 

well known. Hence delineation of the forecast ‘threat 

area’ is also problematic. Finally the preparation of the 

VAA can be manually intensive and during busy 

operational periods this can cause undue pressure for 

operational staff. All these factors cause delays and 

increase the potential for errors in the provision of 

advice that is of critical importance to aircraft operating 

in regions where there are active volcanoes. 

With these issues in mind there is ongoing effort in the 

Bureau that is designed to improve the efficacy of the 

advisory service that is provided. This includes 

improvements in the use of satellite data for detecting 

volcanic eruptions and ash clouds, improvements in the 

utilization of the volcanic ash dispersion model and 

streamlining the warning preparation process. In this 

paper we briefly examine the operational uncertainties, 

using the Indonesian Ruang eruption of 25 September 

2002 as a case study, and then describe efforts directed 

at using available guidance in a more integrated and 

streamlined way for preparation of the volcanic ash 

advisory and a corresponding graphical product. 

Ruang Volcano Eruption of 25 September 2002 

The Ruang volcano is located in the Sangihe Islands of 

Indonesia at 2.28°N 125.425°E and around 0345 UTC, 

25 September 2002, the volcano erupted to a height of 

approximately 20 km in clear conditions. The evolution 

of the ash plume was observed in hourly GMS5 satellite 

data and other satellite data (Tupper etal, 2004). Winds 

over the volcano at the time of the eruption were from 

the east in the layer up to 18 km and most of the ash 

plume moved to the west. A thin layer of ash and SO2

in the layer 18-20 km did move to the east but for the 

purposes of this discussion is not considered further. 

Fig.1a shows the IR1 (BT11) image from GMS5 at 

1230UTC and Fig. 1b shows the corresponding IR1-

IR2 (BT11-BT12) channel difference image, with 

negative differences in orange and red indicating the 

possible presence of ash. It was possible to track the 

boundary of the ash cloud up to this time from a loop of 

the hourly visible, IR1 and IR1-IR2 images and Fig 1a 

also shows a manually analysed boundary for the ash 

plume. Discriminating ash from water/ice clouds and 

defining its boundary as it disperses can be difficult in 

visible and IR imagery, and although the IR1-IR2 image 

may show a well-defined ash signature it does not 

identify the full extent of the ash as shown in Fig 1. For 

this event the IR1-IR2 data showed the presence of ash 

for around 40 hours following the eruption but 

delineation of the ash boundary, or threat area, became 

problematic after just 9 hours. When there is active 

convection in the area and extensive water/ice cloud 

present, uncertainties in delineating the analysed threat 

area increase greatly. 
Session 4 – Page 20 

Guidance on the dispersion of volcanic ash clouds is 

provided by the Hysplit dispersion model (Draxler and 

Hess, 1998) and Fig.2 shows model output for the 

Ruang eruption for the same time as that shown in Fig 

1. This figure shows the integrated concentration from 

the surface to 18 km. Comparison of the boundary 

shown in Fig. 1a with that in Fig. 2 shows general 

agreement but the extent of the analysed ash is 

significantly greater. Such differences can arise 

because the forecast wind field from the underlying 

NWP model is not representative. There are also 

uncertainties in the source term for initialising the 

dispersion model, including 

the height of the eruption plume and the mass 

distribution. Many dispersion models assume a line 

source but in reality there is horizontal spreading of the 

plume in the early stages due to internal dynamics of the 

eruption. This will contribute to greater spreading of 

the plume than models predict. Finally the nominal ash 

concentration that presents a risk to aircraft is not well 

known. These issues lead to uncertainties in delineating 

the forecast threat area. 

These uncertainties mean that the forecaster must use 

satellite data and dispersion model output in an 

integrated way to provide the best assessment of the 

analysed and forecast ash boundary or threat area. 

The Darwin Volcanic Ash Warning Preparation 

System (VAWS) 

The Volcanic Ash Warning Preparation System 

(VAWS) has been developed to enable more integrated 

use of available satellite data and dispersion model 

output and to streamline the generation of the text and 

corresponding graphical volcanic ash products. The 

system also provides a stable framework that should 

simplify the operational implementation of improved 

analysis and prediction components that are underway. 

The VAWS interface includes a map window that 

shows coastlines and all volcanoes in the region, a table 

for the display of relevant volcano details, a layer 

manager and a toolbar, as illustrated in Fig 3. Full roam 

and zoom capabilities are available in the map window 

and the user can select the volcano of interest, using the 

mouse or a text based search, and add the volcano to the 

volcano table. The operator defines the analysed and 

forecast threat areas for 0 hr, +6 hr, +12 hr and +18 hr 

using the mouse and the VAA products are then 

generated in a two-step process. The operator selects 

the ‘Advisory’ icon on the toolbar and this generates a 

text dialogue that shows all the required fields for the 

VAA. Most fields are filled automatically using details 

derived from the graphical interface and the few 

remaining fields, such as the information source, are 

completed manually. The output products are then 

previewed and submitted for dissemination. The 

products include the VAA in text format and a 

corresponding graphical product (Fig 4) that was 

Figure 1. GMS-5 satellite imagery for 1230 UTC, 

25 Sep 2002, showing Ruang eruption cloud. (a) 

IR1 image with manually analysed boundary of ash 

plume, and (b) image of brightness temperature 

difference (IR1-IR2) with blue indicating positive 

differences and orange/red indicating negative 

differences. 

Figure 2. Hysplit dispersion model forecast for 

1300 UTC, 25 September 2002 based on eruption 

at 0345 UTC. 
Session 4 – Page 21 

developed in liaison with regional aviation industry 

representatives. The output products are archived 

together with system files that store relevant 

information for each advisory and for the system status. 

In the development of the user interface several design 

criteria have been adhered to. These include platform 

independence; a responsive graphical interface; the 

need to integrate the system within the Bureau’s 

operational infrastructure (Kelly, etal, 2004); the ability 

to display satellite data, NWP data and output from the 

ash dispersion model using a concept of layers; and, the 

need to archive relevant information for training 

purposes and for ongoing research and development. 

In the first stage of development the focus has been to 

streamline the preparation of the VAA message and to 

generate a corresponding graphical product. Future 

operational implementations of the VAWS system will 

allow for the display of satellite data and dispersion 

model output within the graphical interface and work on 

this is well advanced. 

Operational Experiences 

Operational use of the stage-one system started in 

December 2003 and over 200 VAA’s have been 

generated and disseminated in the period up to 1 June 

2004 with a text and graphical product for each. 

Following feedback from operational forecasters a 

number of upgrades have been provided to improve 

system operation and functionality. The system has 

streamlined the preparation of the VAA message, 

reduced the potential for errors, and feedback from 

forecasters has been positive. Feedback from the 

aviation industry on the format of the graphical product 

has also been positive. It is consistent with the text 

product and satisfies the need, expressed by flight 

planning personnel and pilots, for a concise and simple 

product that shows the variation of the ash boundary 

with time. The simple format also means the product 

remains legible when faxed to pilots at briefing stations 

that may have limited facilities. 

Conclusions 

The Volcanic Ash Advisories (VAA’s) issued by the 

Darwin VAAC are based on an initial report or 

detection of a volcanic eruption or ash cloud, an 

analysis of satellite data to identify and track the ash 

cloud, and a forecast of the movement of the ash 

derived from upper level winds and an atmospheric 

dispersion model. Uncertainties in delineating the 

analyzed and forecast ash boundary or threat area, 

requires intensive manual analysis and integrated use of 

available guidance by the forecaster when generating 

output products for the aviation industry. This process, 

together with preparation of the VAA, can be time 

consuming with resultant delays and potential for errors. 

The Volcanic Ash Warning Preparation System 

(VAWS) is a person-machine user interface that has 

been developed to streamline preparation of the VAA 

text product and automatically generate a corresponding 

graphical product. It enables satellite data and 

dispersion model outputs to be used in a more 

integrated way to delineate the analysed and forecast 

threat areas. The system should also provide a stable 

framework that simplifies the operational 

implementation of improved analysis and prediction 

components that will be developed in the future. The 

system has been in operational use since December 

2003 and feedback from forecasters and the aviation 

industry has been positive. 

Figure 3. Graphical interface for Volcanic Ash 

Warning Preparation System. 

Figure 4. Volcanic Ash Advisory graphical product.
Session 4 – Page 22 

References 

Draxler, R.R. and G.D. Hess, 1998: An Overview of the 

Hysplit_4 Modeling System for Trajectories, 

Dispersion, and Deposition, Aust. Met. Mag., 47, 295-

308. 

ICAO, 2001: Manual on Volcanic Ash, Radioactive 

Material and Toxic Chemical Clouds. ICAO Doc 9691-

AN/954, First Edition-2001. 

Kelly J., A.Donaldson, C.Ryan, J.Bally, J. Wilson and 

R. Potts, 2004: The Australian Bureau of Meteorology’s 

next generation forecasting system. 20th IIPS 

Conference, AMS. 

Tupper A., S. Carn, J. Davey, Y. Kamada, R.J. Potts, F. 

Prata and M. Tokuno, 2004: An evaluation of volcanic 

cloud detection techniques during significant eruptions 

in the western ‘Ring of Fire’. Remote Sensing of 

Environment, 91, 27-46. 
4.6 

Session 4 – Page 23 

SHARED SITUATIONAL AWARENESS AND COLLABORATION THROUGH THE USE OF 

THE VOLCANIC ASH COLLABORATION TOOL (VACT) 

Jeffrey M. Osiensky, NWS Alaska Aviation Weather Unit, Anchorage, AK, USA 

Greg Pratt, NOAA Forecast Systems Laboratory, Boulder, CO, USA 

David J. Schneider, USGS Alaska Volcano Observatory, Anchorage, AK, USA 

Lynn Sherretz, NOAA Forecast Systems Laboratory, Boulder, CO, USA 

There are approximately 100 historically active volcanoes located in an area stretching from Alaska to the 

Northern Kurile Islands. Many of these volcanoes are located within close proximity to the major North 

Pacific (NOPAC) jet routes that traverse the Pacific Ocean. Aircraft flying at speeds of 500 mph or 

greater coupled with the close proximity of these historically active volcanoes to the jet routes, creates a 

potentially serious hazard to aviation with potentially rapid ash encounters. This situation requires a 

highly accurate and rapid response in volcanic ash plume forecasting to the aviation community. Several 

groups are responsible for monitoring and forecasting volcanic ash in the North Pacific area. It is 

imperative that all agencies speak with “one voice” with regard to plume height, aerial extent and 

movement. In order to facilitate real-time collaboration during North Pacific eruptions, a pilot project 

was instituted in 2003 to develop the Volcanic Ash Collaboration Tool (VACT). The VACT consists of 

workstations located at the Anchorage VAAC, the Anchorage Center Weather Service Unit, and the 

USGS Alaska Volcano Observatory, with shared access to satellite and meteorological data. The VACT 

allows for shared situational awareness by providing common views of the data sources, and by allowing 

all groups to view, enhance and annotate graphical data. The project team is continuing to define 

requirements for the system with implementation through rapid software updates. This presentation will 

provide an overview of the VACT, demonstrate some of its current and future capabilities, and propose 

how a system such as this could enhance collaboration between international agencies. 
4.7 

Session 4 – Page 25 

PERSPECTIVES ON OPERATIONAL VOLCANIC ASH WARNINGS 

James Travers, Hordur Thordarson 

Meteorological Service of New Zealand (MetService), Wellington, New Zealand 

ABSTRACT 

MetService is directly involved in many aspects of volcanic ash warnings for a large part of the South Pacific Ocean and 

for New Zealand, and has a long history of involvement with the International Airways Volcano Watch (IAVW). 

MetService operates the Wellington VAAC and is the operational co-ordinator of the New Zealand domestic Volcanic 

Ash Advisory System (NZ VAAS). This is a local enhancement of the Wellington Volcanic Ash Advisory Centre 

(VAAC). MetService personnel have actively participated in the work of the ICAO ASIA/PAC Working Group on 

Volcanic Ash and successor groups. MetService undertakes a National Meteorological Service (NMS) role under contract 

to the New Zealand Government. It also provides a wide range of commercial services to the media, the general public, 

industry and to aviation. As a service provider in these roles, combined with a long and active involvement with ICAO 

and WMO, there have been lessons learned over many years and perspectives gained. This paper offers some of these 

perspectives in terms of international aspects of warning services, the structure of warning systems, development of 

customised services, what seems to work for users and what doesn’t. 

___________________ 

1. Introduction 

 The Meteorological Service of New Zealand 

in Wellington provides a Meteorological Watch 

Office (MWO) and a Volcanic Ash Advisory Centre 

(VAAC). As such we provide SIGMETs and 

Volcanic Ash Advisory (VAA) messages. Work is 

ongoing to improve these messages and warnings by 

increasing the quality of the information used to 

generate these messages, understanding the 

limitations associated with such information and 

gaining an understanding of user needs. 

 The Wellington VAAC area covers much of 

the Southwest Pacific Ocean. The area encompasses 

our own FIR along with parts of the FIR areas of 

Honiara, Nauru, Nadi and Tahiti. This, along with 

the fact that parts of our VAAC area are remote and 

some of the volcanoes are not monitored, presents a 

challenge that we work hard to face. High quality 

information about volcanic activity is available 

within New Zealand but it is sometimes difficult to 

obtain such information from the outer reaches of our 

VAAC area. 

 The VAA format, VA SIGMETs, our 

operational experience via a real example and 

lessons we have learned from interaction with the 

aviation industry will be discussed. 

2. The Volcanic Ash Advisory format and VA 

SIGMETs. 

 It is fair to say that there is some ambiguity 

regarding the role of the VAA and it’s content. In 

some cases the VAA seems to be used as a volcanic 

ash warning for aviation, thus extending its role 

beyond what was originally envisaged. Warnings for 

aviation, whether they pertain to severe icing, 

turbulence or volcanic ash have traditionally been 

disseminated as SIGMETs. MWO offices in some 

parts of the world do not always issue SIGMET 

warnings about volcanic ash. This problem has in 

some cases been addressed, by including 

information, which would normally be contained 

within a SIGMET, in the VAA. 

The view of the MetService is that the VAA 

should remain a mechanism for sharing scientific 

information between VAA Centres and MWOs. 

Warnings for aviation should be contained within 

SIGMETs and if volcanic ash SIGMETs are not 

being issued for one reason or another, then steps 

should be taken to rectify that situation. 

Also, it is our opinion that the current format can 

sometimes contribute to unrealistic expectations 

regarding the accuracy of the advisory. In many 

cases the ash envelope can not be specified 6,12 and 

18 hours forward in time with great precision. It is 

easy for end users to gain the impression that if the 

ash envelope is specified by an area bounded by 

points in degrees and minutes of latitude/longitude, 

then this information can be trusted to the extent that 

flights can be planned directly adjacent to the 

forecast ash envelope area. This is a dangerous 

practice because of the uncertainties involved in 

forecasting the dispersion of an ash envelope. 

Information regarding the initial ash plume height 

may be missing or of poor quality and atmospheric 

forecast models do not always forecast winds 

correctly. 

Given these facts the VAA format should be 

simplified and there should not be a demand for such 

precise forecasts of the ash envelope, 6,12 and 18 

hours forward in time. 
Session 4 – Page 26 

We should work to improve our capabilities but 

we should not imply that we are capable of 

something that we are in fact not. 

2. The eruption of Lopevi in June 2003 

 Lopevi is one of many active volcanoes 

located in the Republic of Vanuatu in the Southwest 

Pacific. This region is important for international 

aviation since flight routes between the United States 

and Australia cross it. It lies within the Wellington 

VAAC area. 

 Vanuatu has few resources for monitoring 

volcanoes and timely, accurate and reliable 

observations can not be always be expected. 

 Lopevi is not monitored by seismographs 

and no warning or indication was received in the 

Wellington VAAC before the volcano actually 

erupted on the 8th of June 2003. An airborne observer 

at 5,000 feet made the initial observation and 

reported ash up to above 40,000 feet. “A massive 

rate of growth and a black/brown plume becoming 

white at high altitude”. 

 This report raises the question, how did an 

observer at 5,000 feet estimate that the ash rose to 

above 40,000 feet? The actual height of the ash 

plume is of course a critical piece of information. 

This needs to be known with a fair degree of 

accuracy in order to be able to forecast the dispersion 

of the ash. Of course the height of the ash plume also 

needs to be known to ascertain the impact on 

aviation. Will it be possible to fly above the plume or 

must it be avoided altogether? 

 These can quickly become important 

questions from an operational point of view. Whether 

or not trans Pacific flights will have to be diverted or 

not may hinge upon the answers. One such diversion 

can easily cost more than $US 100,000. The cost 

would of course be much greater should a flight 

actually encounter volcanic ash, exposing passengers 

and crew to danger and making repairs necessary to 

aircraft costing tens of millions of dollars. 

 We were not able to verify the initial 

observation by using satellite imagery and we did not 

receive any other observations at the time. Therefore 

we had to base our assumptions on the initial 

observation being true. 

 During the 7 days this eruption lasted, we 

only received 7 direct observations and only two of 

these mentioned ash above 10,000 feet. 

This example highlights the uncertainties 

and difficulties involved in forecasting ash dispersion 

from volcanoes in remote areas. VA advisories can 

sometimes give little more than rough estimates of 

ash envelopes. Specifying envelopes far into the 

future with high precision can be misleading. 

Computer models have achieved a high level of 

performance. It must however not be forgotten that 

when initial observations are of poor quality, then 

output from the models will reflect this. 

 It is important that end users know as much 

as possible about volcanic ash and its impact on 

aviation. They also need to understand what VA 

advisories are, and the limitations associated with 

them. 

3. What could be improved?

The most important factor that contributes to 

being able to provide timely and accurate 

information about volcanic ash is close collaboration 

by all agencies involved. Civil aviation authorities, 

Geological and Meteorological services need to keep 

in contact in order to assure a smooth fast flow of 

information whenever the need arises. 

If MWOs are unable to issue VA SIGMETs for 

some reason, then they need to be helped to do so. 

Everyone needs education. Typical eruption 

patterns for major volcanoes, effects of volcanic ash, 

uncertainties involved in ash envelope forecasting, 

etc. need to be known by all involved. 

Observations need to be improved. Advances in 

remote sensing need to be utilised. The importance 

of direct observations must not be forgotten. 

Reconnaissance flights by light aircraft are relatively 

inexpensive compared to many other means of 

observing volcanic ash, and should be exploited 

where possible. 

4. The situation within New Zealand 

 A comprehensive system for monitoring and 

observing volcanoes and a system for interaction 

between agencies involved is in place in New 

Zealand. This is provided through interaction 

between aircraft operators, the Civil Aviation 

Authority of New Zealand, Airways Corporation 

New Zealand, the Institute of Geological and Nuclear 

Sciences and the Meteorological Service of New 

Zealand. Issues illustrated in the Lopevi case do not 

present problems within New Zealand. 

5. Summary 

Timely, simple, accurate and realistic 

warnings are what end users need and this is what we 

should strive to provide. Nothing is gained by 

unnecessary complication that can fuel unrealistic 

expectations and cause confusion. 

 Communications between all the agencies 

concerned with VA warnings need to be maintained 

and strengthened. Good working relationships should 

be developed. Advances in remote sensing must be 

monitored and utilised if they are to increase our 

ability to detect ash. A course of action that could 

lead to significant advances in volcanic ash 

forecasting is to improve monitoring, observations 

and contacts with people in areas outside New 

Zealand. 
4.8 

Session 4 – Page 27 

VOLCANIC CLOUD CONCEPTUAL MODELS FOR VOLCANIC 

ASH ADVISORY CENTRE OPERATIONS 

Andrew Tupper1

, Gerald Ernst2, Christiane Textor3, Kisei Kinoshita4, J. Scott Oswalt5, Daniel Rosenfeld6

1 Bureau of Meteorology, Darwin, Northern Territory, 

Australia, and School of Mathematical Sciences, Monash 

University, Victoria, Australia

2 Geological Institute, University of Ghent, Krijgslaan, 

Ghent, Belgium

3 Laboratoire des Sciences du Climat et de 

l'Environnement, Gif-sur-Yvette, France

4 Faculty of Education, Kagoshima University, 

Kagoshima, Japan 

5

US Navy (retired), USA 

6

Institute of Earth Sciences, The Hebrew University of 

Jerusalem, Israel 

Corresponding author address: A.C. Tupper, Bureau of 

Meteorology Northern Territory Regional Office, PO 

Box 40050, Casuarina NT 0811, Australia. E-mail: 

A.Tupper@bom.gov.au

Abstract

Volcanic Ash Advisory Centre operations are hampered 

by limited ground-based monitoring, imperfect remote 

sensing, and few reliable direct observations. These 

issues are fundamental and must be addressed to improve 

the warning service. However, it is also essential to 

maximise our use of the information available. A basic 

approach to factual uncertainty in operational 

meteorology is to develop conceptual models and related 

procedures that allow fast diagnosis of the nature of an 

event, the degree of risk, and the action required. The 

height of rise of a volcanic cloud, concentration of 

maximum ash, detectability of the cloud, cloud evolution 

and rate of ash deposition are all highly dependent on the 

meteorological environment. Therefore, we must 

consider how, given an assumed level of volcanic 

activity, a volcanic cloud will develop in its 

meteorological context. Here, we use ground and aircraft 

based video observations from Japan and the Philippines, 

remote sensing of the Pinatubo ‘Volcanic 

Thunderstorms’ using particle radius measurement 

techniques, and results from the Active Tracer High 

Resolution Atmospheric Model to discuss modes of 

volcanic convection, relative particle concentrations, and 

plume dispersal. In mid-latitude winter and summer, and 

active and inactive periods of the tropical monsoon, 

conceptual models can be developed which allow 

implementation of pre-defined risk management 

strategies, and quick remote sensing and other report 

interpretation during an event. The further development 

of these models relies on continued close co-operation 

between the aviation, meteorological, and geophysical 

communities. 

Introduction

Despite the rapid advances in remote sensing and 

ground-based monitoring of volcanic clouds, there 

are still large deficiencies in our observation 

system. Remote sensing of eruption clouds using 

meteorological satellites is severely hampered by 

the presence of overlying cloud or of water within 

the eruption cloud (Rose et al., 1995: Tupper et al., 

2004a), human ground-based height observations 

are often severely limited, and instrumental 

monitoring for aviation purposes is patchy (Tupper 

and Kinoshita, 2003). 

This is a difficulty primarily because the 

International Airways Volcano Watch is designed 

as a reactive system; warnings are issued (and 

airspace is closed) based on confident observations 

of volcanic ash, rather than on the possibility of 

volcanic ash. This contrasts with, for example, 

tropical cyclone or mid-latitude severe storm 

warning systems, where often patchy observations 

are coupled with increasingly sophisticated 

conceptual models to produce credible warnings. 

Warnings for volcanic clouds are relatively new, 

and so the application of conceptual models has 

been rather limited to the present. 

Since the 1st International Symposium on Volcanic 

Ash and Aviation Safety, a great deal has been 

added to our understanding of volcanic cloud 

characteristics. The main variations on the basic 

eruption column conceptual models (Self and 

Walker, 1994) are the effect of wind and moisture 

on the development of eruption columns and on the 

observability of the eruptions with remote sensing. 

In this paper, we give some examples of how 

particular understandings of volcanic cloud 

behaviour could affect the warning strategy for that 

event. 

Wind Effects

The effect of wind on eruption columns, 

particularly weaker eruption columns, has been 

covered extensively in theory and observation 

(Ernst et al., 1994: Sparks et al., 1997: Woods, 

1998: Graf et al., 1999). For large eruptions, Graf 

et al. (1999) suggest a difference in the mean height 

of ash of as much 7 km between different wind 
Session 4 – Page 28 

regimes, although these results were based on a 

Cartesian formulation of the model and may be 

overestimated. Fig. 1 shows the effect that strong 

winds can have on a smaller volcanic plume in a 

summer situation – explosions that would normally 

be expected to rise to moderate altitudes shear 

immediately and barely rise above the volcano top. 

Ground based gas and ash measurement stations 

will record anomalously high values in the path of 

the plume and the plume will rapidly extend a great 

distance away from the volcano, possibly affecting 

airports and nearby shipping (Kinoshita et al., 

2003) but posing a relatively low risk to overflying 

aircraft. 

Figure 1 - Explosions from Sakurajima, Japan 

are immediately ‘blown down’ over Sakurajima 

town in a lee wave, 3 August 1999, as a typhoon 

passes close to the area. 

Where minor explosions are known to be a 

consistent feature of activity at a volcano but 

cannot be observed due to bad weather and lack of 

instrumentation, a strategy can be developed which 

allows appropriate NOTAMs and SIGMETs to be 

issued well in advance, based on forecast wind 

variations assuming continuation of the same 

volcanic activity level. 

Moisture Effects

The effect of moisture on plume rise has been 

modelled by simple models for a range of plume 

sizes (Woods, 1993), and by the Active Tracer 

High Resolution Atmospheric Model (ATHAM) 

model for Plinean style eruptions (Graf et al., 

1999). The effect is difficult to show in 

observations because of the other variables 

involved; for example, the plumes of SatsumaIojima in sub-tropical Japan show a pronounced 

seasonality in height, but it is difficult to separate 

wind and stability influences (Matsui et al., 2004). 

As a generalisation, however, moist convection can 

be coincident with, or induced by, volcanic activity, 

and can transport volcanic ash to any altitude 

within the troposphere or lower stratosphere. In 

other words, a large eruption is not required for 

transportation of volcanic ash to cruising levels, 

given the appropriate meteorological conditions. 

Fig. 2 shows a typical (moist) summer situation 

over Sakurajima. On this day, the active vent (on 

the right) was emitting gas, steam and ash 

continuously without explosions, with the result 

that ash-bearing cumulus was forming continuously 

over the vent and dissipating to the north (left of 

picture), leaving fine ash at cloud-top levels. 

Discussions with observers in Japan, Indonesia and 

Papua New Guinea suggest that, in this common 

situation, the height of volcanic ash officially 

reported would be the base of the cloud, since the 

cumulus cloud is not regarded as being volcanic. 

Figure 2 - Cumulus over Sakurajima, 12 Aug 

2002, 0750 UTC. After Tupper & Kinoshita 

(2003). 

A complex picture emerges when considering an 

active volcano interacting with the broader 

environment. Fig. 3 shows the mean brightness 

temperature measured over the Philippines, using 

hourly data for three and a half months following 

the climactic 1991 Pinatubo eruptions. During this 

period, smaller eruptions, secondary explosions and 

‘volcanic thunderstorms’ were common over the 

area (Oswalt et al., 1996), yet not one high level 

ash event could be explicitly detected using the 

split-window algorithm (Tupper et al., 2004b). 

The Pinatubo area was, however, the most active 

source of convection in the whole region during 

that period, as shown by the coldest mean 

brightness temperature (i.e. highest average cloud 

tops) in Fig. 3. Analysis of the diurnal variation 

(Fig.4) shows further that the diurnal cycle of 

convection remained dominant over Pinatubo, but 

that the cycle was shifted significantly earlier when 

compared to nearby topography, due to the 

convection initiation from lower level explosions 

and the heating of the denuded area around the 

mountain. Knowledge of these interactions can 

help to set warning policy; in the absence of any 

other information, deep convection near an 

erupting volcano should be assumed to contain at 

least trace levels of ash. 
Session 4 – Page 29 

Figure 3 - Mean GMS-4 brightness temperature, 

17 June - 30 Sept 1991 (excluding typhoon-cloud 

affected days), Philippines area. 

Figure 4 - Diurnal variation of mean GMS-4 

brightness temperature above Mt Pinatubo 

(solid line) and nearby Mt Lanat area (dashed 

line), Luzon, 17 June - 30 Sept 1991. Values are 

for 20x 20 km boxes, using the same source data 

as Fig. 3. 

Putting the volcanic activity within a large-scale 

meteorological framework also helps us with the 

warning strategy. Fig. 5 shows the situation six 

days after the climactic eruption at Pinatubo; at this 

stage, a southwest monsoon surge was affecting the 

Philippines, with maritime convection cloudiness at 

a maximum in the early morning. On this day, 

radar suggested Mt Pinatubo was venting to about 

20,000 ft (6.1 km), but deep convection (16-17 km) 

was unusually strong in the Pinatubo area. 

Normally, in a situation so cloudy, there could be 

no direct evidence of the ash cloud. However, 

recent work has shown that ash contamination of an 

opaque cold cloud top can be detected by 

measuring the effective radius of the cloud top 

particles using NOAA/AVHRR data. The relative 

smallness of the particles is proportional to the 

amount of ash in the cloud, with ice-laden eruption 

clouds from Pinatubo having measured effective 

radii of around 15 μm, ‘clean’ cumulonimbus tops 

30-35 μm or higher, and ash-contaminated 

cumulonimbus (with ash entrained at lower levels) 

in-between (Rosenfeld and Tupper, 2004). In the 

21 June 1991 case of Fig. 5, cloud tops with a 

notably reduced effective radius of 20-25 μm were 

found in the high level ‘return flow’ extending at 

least 100 km southwest from the volcano (Tupper

et al., 2004b). 

Figure 5 - 900 hPa streamline analysis overlaid 

on GMS-4 infrared image, 21 June 1991. The 

location of Mt Pinatubo, Philippines, is indicated 

by an arrow. Isotach values are indicated in m/s. 

Warning seasonality

We now consider the effect on the International 

Airways Volcano Watch if assumptions about ash 

distribution are made on routine basis. Fig. 6 

shows the consequences of the current system. 

There is a pronounced variation between wet 

season and dry season observation of ash, and 

therefore on the issue of volcanic ash advisories, 

for Semeru volcano in eastern Java, Indonesia. The 

increased warning incidence in the dry season is 

caused partially by the lack of cloud, but also by 

fresh dry winds causing low, long highly visible 

ash plumes. The actual activity at the volcano has 

not had any known seasonal variation over that tenyear period. 

The current warning regime at Semeru is therefore 

focussed mainly on conditions that are relatively 

safe for flying. In the wet season, ash will rise 

higher and be hidden by extensive cumulonimbus 

cloud, so volcanic ash advisories are rarely able to 

be issued. 
Session 4 – Page 30 

Figure 6 - Number of Volcanic Ash Advisories 

issued by Darwin Volcanic Ash Advisory Centre 

for Semeru by month (bars), against average 

rainfall from nearby Surabaya (black line), 

1993-2003 (Davey et al., 2003). 

However, if the assumption of passive ash transport 

within cumulonimbus is made, there is a danger of 

substantial over-warning, as deep convection is 

very frequent around Indonesia’s many active 

volcanoes. To reduce the possibility of overwarning, it will be necessary to a) define a warning 

threshold for ash concentrations, and b) examine 

ash dispersion and advection processes in the 

context of deep convection. 

Ash removal processes

Given a warning threshold, how would we start to 

approach the ash dispersion problem? 

Recent work with ATHAM (Textor et al., 2003: 

Textor et al., 2004a: b) has found a number of 

relevant results: 

1) Hydrometeors are dominant in controlling 

many processes within the volcanic 

plume, even when a relatively dry lower 

troposphere leads to water evaporating 

from ash aggregates as they fall, thus 

giving the appearance of a dry ash cloud. 

2) The collection efficiency of icy particles is 

sensitive to the amount of ice in the 

model, which is dependent upon the 

ambient humidity. 

3) The initial size distribution of the erupted 

particles has a major influence on ash 

aggregation and sedimentation patterns. 

Fig. 7 shows the mean height of particles in two 

size classes for a Plinean eruption, for the range of 

atmospheres described in Textor et al. (2003). 

With these ash-dominant, large eruption clouds, ice 

has a crucial role in the removal of particles from 

the atmosphere, but the small-sized particles of 

interest to aviation have a relatively long residence 

time. 

Since the ash distribution over time is dependent on 

both the eruption and atmospheric characteristics, 

simulations would be necessary for a range of 

eruption types as well as atmospheres. More 

development work will be required to effectively 

model complex interactions such as those described 

for Pinatubo above. 

Figure 7 - Mean height (km) of small (top) and 

large (bottom) particle classes in Plinean style 

eruption clouds developing in a range of 

atmospheric conditions. 

Conclusions

We believe that it is possible to integrate theoretical 

and observational knowledge of volcanic cloud 

interactions with the environment to develop useful 

conceptual models of volcanic ash cloud evolution, 

and then apply these models in an appropriate 

warning strategy. Marrying the complexity of 

volcanic clouds with the already challenging field 

of aviation meteorology is a formidable problem, 

but not impossible. 

Basic understandings of wind, moisture, mesoscale 

and synoptic scale interactions can already be 

applied in a simple way to substantially alleviate 

the effect of incomplete observations. Advanced 

satellite techniques such as effective particle radius 

measurement will occasionally provide explicit 

evidence of ash affecting the microphysical 

processes in deep convection, and improve our 

conceptual models and warning confidence. 

Modelling using ATHAM-style models will 

eventually provide much greater insights into the 

processes within the cloud. 
Session 4 – Page 31 

In order to make substantial progress in these areas, 

it is absolutely necessary to define a warning 

threshold of volcanic ash concentrations. The 

alternative will be substantial over-warning in 

situations where trace amounts of ash can be 

assumed to be present. Intensive investigation of 

aircraft encounters such as those described in this 

volume will aid these efforts. 

References 

Davey, J. P., A. C. Tupper, and R. J. Potts, 2003, 

Volcanic Cloud monitoring issues at the Darwin VAAC. 

WMO/ICAO Third International Workshop on Volcanic 

Ash, Toulouse, France, September 29 -October 3, 2003. 

Ernst, G. G. J., J. Davis, and R. S. J. Sparks, 1994. 

Bifurcation of volcanic plumes in a crosswind. Bull. 

Volcanol., 56, 159-69. 

Graf, H., M. Herzog, J. M. Oberhuber, and C. Textor, 

1999. Effect of environmental conditions on volcanic 

plume rise. J. Geophys. Res., 104, 24309 - 20. 

Kinoshita, K., C.Kanagaki, A.Tupper, and N. Iino, 2003, 

Observation and Analysis of Plumes and Gas from 

Volcanic Islands in Japan. International Workshop on 

Physical Modelling of Flow and Dispersion Phenomena, 

3-5 Sept. 2003, Prato, Italy, Firenze University Press, 78-

83. 

Matsui, T., K. Kinoshita, S. Machida, H. Takahara, M. 

Yamamoto, and C. Kanagaki, 2004, Automatic long-time 

observation of the volcanic clouds at Satsuma-Iojima. 

Volcanic eruption clouds in the Western Pacific - ground 

and satellite based observations and analyses, 

K.Kinoshita, Ed., Kagoshima University, 74-82. 

Oswalt, J. S., W. Nichols, and J. F. O'Hara, 1996, 

Meteorological Observations of the 1991 Mount 

Pinatubo Eruption. Fire and Mud: eruptions and lahars 

of Mount Pinatubo, Philippines, C. G. Newhall and R. S. 

Punongbayan, Eds., Philippines Institute of Volcanology 

and Seismology & University of Washington Press, 625-

36. 

Rose, W. I., D. J. Delene, D. J. Schneider, G. J. S. Bluth, 

A. J. Krueger, I. Sprod, C. McKee, H. L. Davies, and G. 

G. J. Ernst, 1995. Ice in the 1994 Rabaul eruption cloud: 

implications for volcano hazard and atmospheric effects. 

Nature, 375, 477-9. 

Rosenfeld, D. and A. Tupper, 2004. Volcanic eruptions 

revealed through ash affecting satellite-inferred cloud 

properties, submitted to J. Applied Meteorology. 

Self, S. and G. P. L. Walker, 1994, Ash clouds: 

characteristics of eruption columns. First International 

Symposium on volcanic ash and aviation safety, Seattle, 

Washington, US Geological Survey, 65-74. 

Sparks, R. S. J., M. I. Bursik, S. N. Carey, J. E. Gilbert, 

L. Glaze, H. Sigurdsson, and A. W. Woods, 1997. 

Volcanic Plumes. Chichester: Wiley, 589 pp. 

Textor, C., H. Graf, M. Herzog, and J. M. Oberhuber, 

2003. Injection of gases into the stratosphere by 

explosive volcanic eruptions. J. Geophys. Res., 108,

4606 doi: 10.1029/2002JD002987. 

Textor, C., H. Graf, M. Herzog, J. M. Oberhuber, W. I. 

Rose, and G. G. J. Ernst, 2004a. Volcanic Particle 

Aggregation in Explosive Eruption Columns Part I: 

Parameterisation of the Microphysics of Hydrometeors 

and Ash. submitted paper. 

——, 2004b. Volcanic Particle Aggregation in Explosive 

Eruption Columns Part II: Numerical Experiments. 

submitted paper. 

Tupper, A. and K. Kinoshita, 2003. Satellite, air and 

ground observations of volcanic clouds over islands of 

the Southwest Pacific. South Pacific Study, 23, 21-46. 

Tupper, A., S. Carn, J. Davey, Y. Kamada, R. Potts, F. 

Prata, and M. Tokuno, 2004a. An evaluation of volcanic 

cloud detection techniques during recent significant 

eruptions in the western 'Ring of Fire'. Remote Sens. 

Environ., 91, 27-46, doi:10.1016/j.rse.2004.02.004. 

Tupper, A. C., J. S. Oswalt, and D. Rosenfeld, 2004b. 

Satellite and radar analysis of the 'volcanic storms' 

following the paroxysmal eruption of Mt Pinatubo, 

Philippines, June-September 1991. for submission to J. 

Geophysical Research, under preparation. 

Woods, A. W., 1993. Moist convection and the injection 

of volcanic ash into the atmosphere. J. Geophys. Res., 

98, 17627-36. 

——, 1998, Observations and models of volcanic 

eruption columns. The Physics of Explosive Volcanic 

Eruptions, J. S. Gilbert and R. S. J. Sparks, Eds., 

Geological Society, London, 91-114.
4.9 

Session 4 – Page 33 

VOLCANIC ASH ADVISORY SUPPORT 

FOR THE U.S. DEPARTMENT OF DEFENSE 

Richard Gonzalez and Charles Holliday 

Air Force Weather Agency, Offutt AFB, Nebraska U.S.A. 

ABSTRACT 

The Air Force Weather Agency (AFWA) 

issues volcanic ash advisory products tailored for 

U.S. Department of Defense (DoD) support. 

AFWA’s Meteorological Satellite Applications 

Branch (XOGM) monitors a variety of sources for 

volcanic ash plume activity, and creates both 

alphanumeric and graphic advisory products 

supporting DoD resource protection. In addition, 

AFWA serves as a hot backup for the Washington 

Volcanic Ash Advisory Center (W-VAAC). 

BACKGROUND 

Volcanic ash is a major concern to the 

DoD. Several U.S military installations stand 

within the shadows of active volcanoes in Asia, 

the Pacific, and the Mediterranean, while DoD 

aircraft regularly traverse regions susceptible to 

ash plumes from active volcanoes. Besides high 

altitude (>30,000 ft) transit of active volcanic 

chains, the DoD has localized operations in 

Southeast Asia, the Marianas Islands, and other 

regions. These areas frequently require sustained 

flight at much lower altitudes (<20,000 ft) near 

volcanoes increasing aircraft vulnerability to 

airborne ash. 

AFWA at Offutt AFB, Nebraska provides 

volcanic ash advisory support for DoD customers. 

AFWA’s XOGM issues a suite of text and 

graphical products tailored to DoD requirements 

for volcanic ash advice and forecasts. With U.S 

Forces operating worldwide, a standardized and 

consistent set of timely advisory and forecast 

products from one source is essential to DoD 

planners for both situational awareness and 

decision-making. 

SATELLITE DATA 

Satellite imagery plays a critical role in 

surveillance of recently active or potentially active 

volcanoes worldwide. In addition, it is used to 

verify and provide quality control for ash 

dispersion model forecast graphics output. 

 AFWA’s operational global satellite 

database consists of five geostationary satellites 

providing frequent imagery refresh coverage of 

suspect areas. In addition, AFWA receives higher 

resolution global polar orbiter data over areas of 

interest via stored readout from two National 

Oceanographic and Atmospheric Administration 

(NOAA) and four DoD Defense Meteorological 

Satellite Program (DMSP) satellites. 

XOGM augments the above imagery with 

data relayed from the Air Force MARK IVB 

network of tactical direct readout sites. This 

permits timely review of data over volcano regions 

at full resolution from both NOAA and DMSP 

satellites. In addition, the direct readout capability 

enables AFWA to leverage data from several older 

polar satellites for which stored readout is no 

longer possible. 

XOGM uses the Satellite Image Display 

and Analysis System (SIDAS) to examine ash 

plume characteristics. This AFWA interactive 

graphics toolkit allows analysts to display, 

interrogate, and manipulate satellite imagery to 

maximize imagery data extraction. 

SIDAS facilitates multi-spectral analysis 

including infrared channel differencing when 

meteorological cloud or darkness inhibits visual 

imagery inspection of ash plumes. In addition, 

data from other sources (conventional surface and 

upper air data, cloud drift winds, numerical 

analysis and prognosis fields) can be overlaid on 

the image to assist in the analysis of plume height 

or other features. 
Session 4 – Page 34 

OTHER DATA SOURCES 

Global monitoring of active volcanoes and 

airborne ash is an extensive task, and cannot be 

effectively accomplished with review of satellite 

imagery alone. Aircraft, surface reports, and alerts 

from volcano observatories often provide the first 

notification of an eruption. 

 A primary method to alert analysts to 

these reports is to use automated text filter 

capabilities to scan existing alphanumeric bulletin 

traffic across the DoD’s Automated Weather 

Network (AWN). This XOGM developed 

software package interrogates Meteorological 

Aerodrome Report (METAR) observations, Pilot 

Reports (PIREPS), Significant Meteorological 

Information (SIGMET) bulletins, and civilian 

Volcanic Ash Advisories (VAAs). When ash is 

detected, the software alerts branch analysts and 

highlights the alphanumeric data for closer review 

and crosscheck with satellite imagery. 

Although limited to a small number of 

volcanoes, AFWA leverages web cams as an 

additional method of monitoring. XOGM 

developed software provides a grid display of 

multiple volcano web cam sites with continuously 

updating animated image loops covering the last 

30 min. This greatly assists the analyst in 

effectively managing limited time by eliminating 

the need to contact each web site for single image 

updates.

PRODUCTS 

 AFWA issues alphanumeric advisory and 

forecast graphic products when ash is detected or 

suspected. Bulletin updates on ash activity occur 

at six-hour intervals until the end of the event. As 

a measure of global activity for 2003, XOGM 

issued advisories for 450 initial eruptions from 38 

volcanoes. Ongoing activity necessitated over 

2,000 updates. Ash plumes below 20,000 ft 

accounted for 75% of the notices. 

AFWA bases its forecast graphic products 

upon the University of Alaska, Fairbanks’ 

volcanic ash dispersion model called PUFF (not an 

acronym) and wind fields from the National 

Weather Services’ (NWS) Global Forecast System 

(GFS). The current PUFF graphical user interface 

version includes customization for AFWA by the 

Johns Hopkins University’s Applied Physics Lab. 

PUFF run length is dependent upon the height of 

the initial ash cloud and the duration of the 

eruption. Low-level eruptions (<20,000 ft) have a 

six hour run period with forecast intervals of three 

hours. Maximum run lengths for higher-level 

eruptions may extend to 48 hours with forecast 

intervals of 12 hours. Forecast graphics include 

both animated and static products. 

The animated forecast is a color graphic 

product with dynamic, optimized geographical 

boundaries to incorporate the entire ash cloud at its 

maximum forecasted extent. Ash is visualized 

using a consistent color scheme, with ash plotted 

in five thousand foot (Kft) bins from the surface 

(Sfc) to 55 Kft. 

The static graphic product is a set of fourpanel charts for forecast intervals extracted from 

the PUFF model run. This is a color graphic 

product with fixed geographic boundaries and ash 

plotted within four flight levels – Sfc-12Kft, 12-

24Kft, 24-36Kft, and 36-55Kft. 

In addition to actual eruption situations, 

AFWA also prepares forecast products in both 

animated and four-panel static format for 

hypothetical eruptions. These automated products 

assist DoD flight planners in route decisions near 

active volcanoes, particularly during exercises and 

contingency operations. 

COMMUNICATIONS 

AFWA disseminates alphanumeric ash

advisories via the AWN. In addition, the bulletins 

are e-mailed to numerous customers who have a 

direct interest in the products. Air Force 

customers include the Tanker Airlift Control 

Center (Scott AFB, IL), Operational Weather 

Squadrons, and selected Base Weather Stations. 

Products are e-mailed to other DoD agencies as 

well, such as the Navy’s Meteorological & 

Oceanographic Centers. For eruptions likely to 

directly impact DoD facilities, product submission 

is preceded by telephonic communication to 

ensure timely notification. 

XOGM posts volcanic ash imagery and 

graphic forecast products on the Joint Air Force 

and Army Weather Information Network 

(JAAWIN) web site for ease of access for 

customers. JAAWIN is a web-based system 

which provides DoD customers access to over 
Session 4 – Page 35 

800,000 products daily. These include all forms of 

meteorological data products – satellite, model 

output, radar, lightning, observations, charts, space 

environment, and a myriad of other products. The 

JAAWIN Environmental Events page features the 

volcanic graphic products divided into four 

regions around the globe – the Americas, 

Europe/Africa, North Pacific, and South Pacific. 

For each active volcano, customers have direct 

access to alphanumeric bulletins, satellite imagery, 

and both the animated and four panel PUFF 

graphics. 

WASHINGTON VAAC BACKUP 

AFWA provides backup for the W-VAAC 

to ensure continuity of operations during power 

failures, communications outages, or other 

contingencies. During backups, AFWA assumes 

the monitoring function for the W-VAAC and 

issues volcanic ash text and forecast graphic 

products on behalf of Washington. To ensure 

readiness, AFWA and the W-VAAC hold 

quarterly exercises to test the effective execution 

of these duties. During 2003, AFWA provided 

immediate “hot” backup five times due to 

communications difficulties. 

SUMMARY 

AFWA is the DoD focal point for volcanic 

ash advisory products including monitoring, 

forecasting, notification and product 

dissemination. This is a mission of global extent 

carried out 24/7 by AFWA’s Meteorological 

Satellite Applications Branch (XOGM). These 

efforts ensure planners and flight crews have the 

information needed to ensure mission 

accomplishment and resource protection. 
4.10 

Session 4 – Page 37 

WEB ACCESS TO THE VOLCANIC ASH ADVISORY DATABASE 

Paula Dunbar, National Geophysical Data Center, Boulder, CO, USA 

Grace Swanson, NOAA Satellite Services Division, Camp Springs, MD, USA 

Volcanic ash is a significant hazard to aviation and 

can also affect global climate patterns. To ensure 

safe navigation and monitor possible climatic 

impact, NOAA’s Volcanic Ash Advisory Centers 

(VAACs) track volcanic ash eruptions and monitor 

surface weather observations, aircraft pilot reports, 

and satellite imagery for ash clouds. The NOAA 

Washington VAAC is part of the National 

Environmental Satellite, Data, and Information 

Service (NESDIS) and the National Weather 

Service (NWS). The Satellite Analysis Branch 

(SAB) of NESDIS and the National Centers for 

Environmental Prediction of the NWS share duties 

as the regional Washington VAAC located in 

Camp Springs, Maryland. The Washington VAAC 

area of responsibility includes the continental 

United States and southward through Central 

America, the Caribbean to 10 degrees South in 

South America, and the United States controlled 

oceanic flight information regions (FIRs). The 

NOAA Anchorage VAAC is part of the Alaska 

Aviation Weather Unit in Anchorage and is 

responsible for Alaska and Anchorage FIRs and a 

small portion of Russia north of the Kamchatka 

peninsula. 

NOAA’s VAACs issue two products after a 

volcanic eruption. The first product, the Volcanic 

Ash Advisory (VAA) statement, includes text 

describing current volcanic activity and ash cloud 

position. The second product (when appropriate), 

the Volcanic Ash Forecast Transport and 

Dispersion (VAFTAD) model, provides a forecast 

of ash location in the atmosphere for the next 48 

hours. All of this information is provided to the 

Federal Aviation Administration, the U.S. 

Geological Survey, Meteorological Watch Offices, 

climate analysts, and scientists in other countries. 

The VAAC system had its roots in the 1980’s 

when the NESDIS SAB began to provide the 

aviation and volcanology community real-time 

analysis of satellite products to support response 

actions to volcanic ash eruptions. In 1997, the 

Washington VAAC joined a global network 

formed by the International Civil Aviation 

Organization to provide worldwide coverage of 

volcanic ash events. Since the beginning of its 

volcanic ash monitoring program, the NESDIS 

SAB has maintained an archive of Volcanic Ash 

Messages, VAFTAD model output, and 

substantiating information. The substantiating 

information includes surface weather observations, 

pilot reports, volcanic observatory reports, news 

media reports, and satellite imagery for each 

event. The National Geophysical Data Center 

(NGDC) has had this analog archive scanned into 

image format and is now making it available on 

the web. 

The digital archive, known as the Volcanic Ash 

Advisory Database (VAADB), currently consists 

of information from over 600 folders representing 

different eruptive episodes. Since the Washington 

VAAC originally had global responsibility for 

volcanic ash monitoring, the VAADB includes 

information on over 40 volcanoes from all over the 

world (Figure 1). The current database includes 

information from 1996 to 2001. It will eventually 

be extended back to the 1980’s and will also 

include advisories issued after 2001 which are 

already in digital format. The VAADB images are 

being delivered over the Web using a geospatiallyenabled relational database management system 

using a text-based search interface (Figure 2). 

Users can search the database using one or more 

of the following search parameters: 

• Volcano name 

• General location by description (region or 

country) or latitude-longitude entry 

• Beginning date of the eruption 

• Type of information (advisory or 

substantiating), 

• Type of image (VAA, VAFTAD, Ash 

analysis graphic, Satellite imagery, Media 

report, Pilot report, Volcano Observatory 

report, Surface Weather Observation, etc.) 
Session 4 – Page 38 

Figure 1. Volcanoes included in the Volcanic Ash Advisory Database. 

Examples of the types of output and images 

currently available online are shown in figures 3-6. 

Figure 3 shows the result of searching the database 

for all images from Popocatepetl in Mexico. 

Figures 4-6 provide examples of advisory 

information for Popocatepetl during the March 

1996 eruptive episode. 

The VAADB will eventually be accessible via an 

interactive map interface and will be integrated 

into the NGDC Natural Hazards interactive map 

that provides Web-based GIS access to volcano, 

earthquake, tsunami, and auxiliary geospatial data. 

In addition, links will be provided to the 

Smithsonian’s Global Volcanism Database, 

associated images in NGDC’s natural hazards 

slide sets, and GOES imagery from the 

Comprehensive Large Array-data Stewardship 

System GOES active archive. 

Volcanic ash modelers, climate analysts, and 

volcanologists will soon have web-access to a vast 

collection of data from past volcanic events. The 

VAADB website is listed below: 

http://www.ngdc.noaa.gov/seg/hazard/vol_ash.html
Session 4 – Page 39 

Figure 2. Search interface for the Volcanic Ash Advisory Database. 

Figure 3. Results of searching the VAADB for Popocatepetl. 
Session 4 – Page 40 

Figure 4. Example of Volcanic Ash Message from the VAADB for Popocatepetl. 

Figure 5. Example of Ash Analysis Graphic from the VAADB for Popocatepetl. 
Session 4 – Page 41 

Figure 6. Example of VAFTAD output from the VAADB for Popocatepetl. 
P4.1 

Session 4 – Page 43 

WASHINGTON VOLCANIC ASH ADVISORY CENTER (VAAC) OPERATIONS 

Gregory M. Gallina and Davida Streett 

Washington VAAC-NOAA/NESDIS/Satellite Services Division 

Introduction 

The Washington Volcanic Ash 

Advisory Center (VAAC) monitors and 

tracks airborne volcanic ash and 

disseminates text and graphical messages 

to the global aviation community. The 

Washington VAAC is part of a global 

network created by the International Civil 

Aviation Organization to provide nearly 

worldwide coverage of volcanic ash 

events. This network of centers includes 

VAACs, Meteorological Watch Offices 

(MWOs), and Area Control Centers 

(ACCs). VAACs provide ash information 

to MWOs (and vice versa) and the MWOs 

issue ash warnings for aviators by 

SIGMETs. VAACs also provide ash 

information to ACCs, and ACCs issue 

notices to in-flight aircraft via NOTAMs 

and ASHTAMs. VAAC information and 

products are also broadly disseminated to 

a variety of other users concerned about 

airborne ash (Fig. 1, not shown). 

Globally, there are nine VAACs 

(Anchorage, Buenos Aires, Darwin, 

London, Montreal, Tokyo, Toulouse, 

Washington and Wellington), each having 

responsibilities for volcanic ash eruptions 

within their ICAO-determined boundaries 

(Fig. 2, not shown). Most of the world’s 

airspace is facilitated by one of the 

VAACs; however, there are some gaps, 

usually over oceans and areas without 

active volcanoes. Notice in Figure 2 that 

the Washington VAAC area of 

responsibility includes the contiguous 

U.S., Mexico, Central America, South 

America north of 10°S, parts of the Pacific 

(including Hawaii and the Southern 

Mariana islands) and Atlantic Oceans 

(including the Caribbean). Under normal 

circumstances, VAACs will only issue ash 

advisories and trajectory models when an 

eruption or ash occurs within their area of 

responsibility. Each VAAC ensures that 

ash products (described more in VAAC 

Products section below) are issued when 

an eruption or airborne ash occurs within 

their geographic area of responsibility and 

the appropriate MWOs are 

contacted/receive the information so 

warnings (SIGMETS) can be produced. 

The Washington VAAC is a joint 

collaboration between the Satellite 

Analysis Branch (SAB) of the National 

Environmental Satellite, Data, and 

Information Service (NESDIS) and the 

NCEP Central Operations (NCO) of the 

National Weather Service. Although the 

Washington VAAC was chartered in 1997 

by ICAO, NESDIS and the NWS have a 

long history of monitoring volcanic ash 

events. The NESDIS component, SAB, 

has had over 20 years of experience 

monitoring volcanic ash via satellite 

imagery. The NWS component, NCO has 

worked with volcanic ash by utilizing ash 

trajectory models for the past 10 years. 

Both organizations are part of the National 

Oceanic and Atmospheric Administration 

(NOAA). 

Products and Services

When ash is reported or detected 

within the Washington VAAC boundaries, 

the person on-duty discontinues other 

operational activities and immediately 

begins gathering information about the 

ash/eruption. The VAAC analyst’s first 

priority is to notify the affected MWO(s) 
Session 4 – Page 44 

to facilitate their issuance of a Volcanic 

Ash SIGMET. Next, the analyst prepares 

a text product known as the Volcanic Ash 

Advisory (VAA) (Fig. 3). A VAA is 

intended to provide the aviation 

community with all of the pertinent 

information that we have about the 

airborne volcanic ash. Ideally a VAA will 

contain information on the eruption, the 

location, height and amount of ash, the 

current movement(s) of the ash (noting 

when different areas of ash move in 

different directions) and other information. 

VAA are updated at least every six hours, 

but sooner if the ash situation changes 

substantially. In addition to the VAA, the 

Washington VAAC also issues two 

graphical products (an ash analysis and an 

automated forecast) and is preparing to 

issue a third product (a forecast created by 

a person). The VAA is distributed through 

many communication networks, such as: 

AFTN, AWIPS/N-AWIPS (NWS 

systems), GTS, WAFs, Family of 

Services, under the identification header 

FVXX## KNES (where ## denotes a 

number in the range of 20 to 27). Also, as 

a service of the Washington VAAC, a 

graphical analysis of the detectable ash 

drawn on a map background (Fig. 4) is 

issued but is currently available only on 

our website. 

For flight planning purposes, an 

ash trajectory and dispersion model is also 

issued. This model, known as the 

VAFTAD (Volcanic Ash Forecast 

Transport and Dispersion), graphically 

depicts predicted ash location at 12, 24, 36 

and 48 hours. It is based on the aviation or 

ETA numerical weather models and 

manual inputs of ash height, summit 

height, eruption duration, and an 

adjustment factor to modify ash amounts. 

At each time period, the forecasted ash is 

depicted at low, middle and high levels of 

the atmosphere, and there is a composite 

showing all atmospheric levels from 

surface to 55,000 ft. The VAFTAD is 

available via the VAAC website and 

satellite broadcast under bulletin headers 

PHBE10KWBC and PHBI10KWBC. In 

the future, a new product (the Volcanic 

Ash Graphic) will be issued that represents 

a VAFTAD with its output adjusted and 

hopefully improved by a forecaster. A 

variety of current GOES satellite imagery 

over selected volcanoes can be viewed on 

our website (Fig. 5, not shown) at 

www.ssd.noaa.gov/VAAC/. We also 

expect to soon have available on our 

website, a Geographic Information System 

(GIS) based display of ash as seen in 

MODIS (Moderate-Resolution Imaging 

Spectroradiometer) satellite imagery using 

a special optimized multi-spectral 

algorithm. Although this should provide 

an excellent snapshot of the ash at a given 

instance, it will not be nearly as current or 

frequent as the GOES imagery. 

Washington VAAC is staffed 24 

by 7; however, its personnel are multitasked, performing a number of 

meteorological tasks unrelated to 

volcanoes. In the event of a Washington 

VAAC outage, the United States Air Force 

Weather Agency serves as the Washington 

VAAC backup and will create and 

disseminate the VAA and VAFTAD. 
Session 4 – Page 45 

FVXX22 KWBC 112209Z 

VOLCANIC ASH ADVISORY 

ISSUED: 2003MAY11/2200Z VAAC: WASHINGTON 

 

VOLCANO: ANATAHAN 0804-20 

LOCATION: N1621E14540 AREA: MARIANA ISLANDS 

 

SUMMIT ELEVATION: 2585 FT (788 M) 

ADVISORY NUMBER: 2003/007 

 

INFORMATION SOURCE: GOES-9 IMAGERY. GFS MODEL WINDS FORECAST. GUAM MWO. 

ERUPTION DETAILS: ERUPTION OCCURRED AROUND 10/0730Z AND EMISSIONS 

CONTINUE TO OCCUR 

 

OBS ASH DATE/TIME: 11/2118Z 

OBS ASH CLOUD: SFC/FL170 N1621E14256 - N1800E14417 - N1900E14200 - N1706E13403 - 

N1559E13340 - N1339E14423 - N1428E14502 - N1621E14256 MOVING W 15 KNOTS. 

SFC/FL080 17 NM WIDE LINE OF ASH BETWEEN N1621E14540 - N1611E14326. 

ASH IS MOVING WEST 20 KNOTS. 

FCST ASH CLOUD+06H: NOT AVBL 

FCST ASH CLOUD+12H: NOT AVBL 

FCST ASH CLOUD+18H: NOT AVBL 

 

REMARKS: A LARGE AREA OF MID-LEVEL ASH IS MOVING WEST WITH THE 

THICKEST OF THIS ASH BETWEEN 140E AND 143.5E. FAINTER ASH 

EXTENDS TO ABOUT 134E. IN ADDITION A NARROW LOW LEVEL ASH PLUME 

CAN STILL BE SEEN EXTENDING FROM THE SUMMIT TOWARD THE WEST. 

NEXT ADVISORY: WILL BE ISSUED BY 12/0400Z. 

Guam 

Figures 3 and 4: Example of VAA Text Product and associated Graphic. 

Example from May 2003 Eruption of Anatahan in Southern Mariana Islands. 
Session 4 – Page 46 

Ash Detection Methods

Viewing ash in satellite imagery 

provides ash location, height and speed 

information that is useful in creating VAA. 

The Washington VAAC relies primarily 

on GOES satellite imagery since it is 

available every 15 or 30 minutes, 

throughout most of the VAAC area. Polar 

orbiting satellites with their high spatial 

resolution provide supplementary 

information, but do not have the temporal 

resolution of GOES imagery. 

Satellite detection algorithms using 

a variety of visible and infrared 

wavelengths and combinations of 

wavelengths (“multispectral” imagery) are 

optimized to enhance ash detection and 

help discriminate ash from weather clouds. 

In Fig. 6 (not shown), each panel is an 

example of GOES satellite imagery used 

in ash detection: Visible, 10.7 mm Infrared 

(IR), 3.9 mm “shortwave” IR, Principal 

Component Imagery (PCI) 3, a multispectral technique created by CIRA, and 

Gary Ellrod’s multi-spectral technique. 

For volcanoes within the GOES-E 

footprint, the Washington VAAC 

primarily uses 2 forms of multispectral 

imagery that rely on fixed weighting and 

one form that varies with image content. 

The CIRA algorithm utilizes channels 2, 4, 

2 and with fixed weighting designed to 

enhance ash versus weather cloud. Gary 

Ellrod’s algorithm uses channels 2 4 and 6 

with fixed weighting of the channels. 

Since late 1999, the Washington VAAC 

has relied heavily on the use of Principal 

component analysis of GOES imagery. 

According to Hillger and Ellrod 2003, the 

PCI technique “determines which part of 

the multi-spectral signal is common to all 

the images (or ... bands) and separates that 

information from other image information 

that is sensed only by image differences or 

multiple image combinations. Whereas the 

original images...[generally] contain 

redundant information, the...component 

images contain independent information 

separated out of the original images. This 

allows the image analyst to see the 

independent components in multi-spectral 

imagery.” The VAAC uses PCI-3 (GOES12 channels 2, 4, 6) and GOES-10 

channels 2, 4, 5) for ash detection and 

discrimination of ash versus steam. The 

VAAC uses a split window technique for 

satellites (GOES 9, GOES 10, NOAA, 

MODIS) that have a 12 micron channel. 

Besides satellite imagery, many 

other data sources provide crucial 

information necessary to an accurate 

VAA. Pilot reports (AIREPS), airline 

phone calls, surface weather observations 

(METAR/SPECI), volcanological 

observatories, SIGMETs, upper air 

observations (radiosondes), numerical 

weather models, and media reports are 

useful. To help find references to volcanic 

ash in the multitude of 

telecommunications traffic, the 

Washington VAAC uses an automatic 

alert notification program based on a 

keyword search engine. The program 

scans for “words” such as ASH, PLUME, 

VA, WV, FV, VOLCANO, VOLC, and 

CENIZA as well as some individual 

volcano names and whenever a message is 

found with these keywords, an e-mail alert 

is sent to the VAAC and an audible alarm 

sounds. 

Six Year Statistics

On November 1st, 2003, the 

Washington VAAC celebrated six full 

years of service to the aviation 

community. Coincidently, a mile-stone 

was surpassed the same day as the 7500th 

VAA was disseminated. Figure 7 shows 

the annual distribution of VAA and 
Session 4 – Page 47 

graphical depiction of ash clouds during 

the six years of service. 

During those six years, VAA were 

written for 26 volcanoes, 17 that are 

located inside the VAAC boundaries, as 

well as, for 9 volcanoes in support of other 

VAACs or ash that moved across into the 

Washington VAAC’s airspace of 

responsibility. The majority of VAA 

have been written for 2 volcanoes: 

Tungurahua with 2677 VAA, followed by 

Soufriere Hills with 2589. Popocatepetl 

(812), Guagua Pichincha (397) and 

Anatahan (289) round out the top five. 

Similarly, the graphical depiction 

of ash seen on satellite imagery has been 

produced for 16 volcanoes (13 within the 

Washington VAAC). Graphics were 

created mostly for Soufriere Hills (1176), 

followed by Tungurahua (492), 

Popocatepetl (275), Anatahan (162), and 

Colima and San Cristobal tied for fifth 

with 34 each. 

Authors note: Due to the unavailability of 

color graphics, Figures 1, 2, 5 and 6 are 

available from the authors. Please contact 

them at Greg.Gallina@noaa.gov, 

Davida.Streett@noaa.gov or 301-763-

8444 in Camp Springs, Maryland, USA. 

 

264 127

925

266

936

225

2082

417

752

220

955

279

1586

742

0

250

500

750

1000

1250

1500

1750

2000

2250

1997 1998 1999 2000 2001 2002 2003

VAAs

Graphics

Nov. 

Totals* : 7500 VAA 

 2276 Graphics

* - VAA sent from Nov. 1, 1997 thru Oct. 31, 2003

Figure 7: Number of Volcanic Ash Advisories (VAA) and Graphics for the six 

years since the VAAC was created in November of 1997 through October 2003. 
P4.2 

Session 4 – Page 49 

IMPROVEMENT OF ASH CLOUD INFORMATION BY TOKYO VAAC 

Takeshi Koizumi, Japan Meteorological Agency, Tokyo, Japan 

Yoshihiko Hasegawa, Yasuhiro Kamada, Masamichi Nakamura 

Introduction 

The Japan Meteorological Agency 

(JMA) is operating Tokyo Volcanic Ash 

Advisory Center (Tokyo VAAC) that is 

responsible for monitoring volcanic ash clouds 

in Asia/Western Pacific area and issuing 

Volcanic Ash Advisories (VAAs), one of 9 

VAACs are being operated in the world in order 

to mitigate or prevent disasters of airplanes 

caused by volcanic ash. 

 Tokyo VAAC monitors satellite 

imagery and gathers domestic and foreign 

reports on volcanic activities. When volcanic ash 

is likely to affect to any routes in the area of 

responsibility (Fig. 1), the Tokyo VAAC issues 

VAAs, which includes the present status and 

forecast information of volcanic ash clouds in 

the text and graphical format used by 

Meteorological Watch Offices, civil aviation 

authorities and other related organizations. 

From March 1997 to May 2004, the 

Tokyo VAAC has issued 411 VAAs regarding 

volcanic eruptions and volcanic ash clouds 

within the area of responsibility.

Automatic Issuance of VAA for Volcanoes in 

Japan 

JMA operates not only the Tokyo 

VAAC but also four Volcano Observations and 

Information Centers (VOICs) that cover all 108 

active volcanoes in Japan.

The four VOICs, namely Sapporo, 

Sendai, Tokyo and Fukuoka are watching 26 

major active volcanoes 24 hours a day, 7 days a 

week using, for example, seismometers, tilt 

meters, GPS networks, and television cameras. 

Quick response teams under the VOICs conduct 

regular observations for the rest of 82 volcanoes 

in ‘moderate’ activities. When eruption 

reports from VOICs arrive at the Tokyo VAAC, 

the computer system translates the messages into 

VAAs and issues them automatically in order to 

immediately inform the occurrence of eruption 

(Fig. 2). 

 The automation is performed taking 

advantage of the fixed format of eruption reports 

from the VOICs. The Tokyo VAAC has 

established several communication routes under 

cooperation with adjacent VAACs, airlines (e.g., 

pilot reports), volcano observatories (e.g., 

KVERT and PHIVOLCS) so that appropriate 

and accurate information about volcanic 

eruptions could be immediately and correctly 

acquired. Based on such information, though, 
Session 4 – Page 50 

VAAs are issued manually because the software 

used in the automatic transaction cannot cope 

with various 'free' format massages. 

 After the issuance of each VAA 

triggered by an eruption report, VAAs, which 

contain ash cloud dispersion, are issued 

manually when ash clouds are detected on 

satellite imagery. 

Improvement of Forecast Precision of 

Volcanic Ash Cloud Dispersion 

Based on the improvement of 

numerical weather prediction model for the area 

in and around Japan, the Tokyo VAAC 

developed a detailed Lagrangian model that 

takes the effect of vertical wind into account. 

The grid and time interval has been improved to 

20 km from 100 km and 1 hour from 6 hours, 

respectively. The model has been available 

since November 2003.

When ash clouds are released from 

volcanoes in Japan and Kuril Is. area, the 

improved model above (New Model) is used to 

calculate ash cloud dispersion for the issuance of 

VAA. Because of the limited application area of 

the New Model, the previous model (grid 

interval: 100 km; time interval: 6 hours) takes 

over the calculation using the final forecasted 

area by the New Model as an initial when the 

forecasted area of ash clouds reaches the 

boundary of the model.

Open to Public using Website 

The web-site of the Tokyo VAAC has 

been open to public since December 2003. The 

contents, though, have not included issued VAAs. 

The Tokyo VAAC is now conducting a revision 

to the web-site so that VAAs will be available by 

the end of next March. The URL of Tokyo 

VAAC web-site is:

http://www.jma.go.jp/JMA_HP/jma/jma-e

ng/jma-center/vaac/index.html 
Session 4 – Page 51 

Tokyo VAAC

Eruption Report 

(fixed format in Japanese) 

 > Volcano name 

 > Eruption time 

 > Plume height 

 > Extending direction of Plume

Volcanic Ash Advisory 

 > Eruption time 

 > Plume height and dir. 

> Wind information 

 above the volcano.

VOIC

Automatic transaction

MWOs, Airlines

VAACs, etc. 

Fig.1 Area of responsibility of Tokyo VAAC (inside of the bold line) 

Fig. 2 Automatic issuance of VAA triggered by eruption report 

from Volcano Observations and Information Center (VOIC) 
P4.3 

Session 4 – Page 53 

THE MONTREAL VAAC TOOLBOX: WHEN EVERY SECOND COUNTS 

Mark McCrady, Serge Trudel, Jean-Philippe Gauthier and Rene Servranckx 

Canadian Meteorological Centre, Meteorological Service of Canada, Dorval, Quebec, Canada 

Following the designation of the Montreal VAAC, the task of volcanic ash detection and forecasting was 

given to the 24/7 operational meteorologists of the Canadian Meteorological Centre (CMC). This was 

done so that, in the case of an actual volcanic eruption on Canadian territory, or in the case of inherited 

volcanic ash from neighbouring VAACs, a fast first response would be possible in order to support the 

Meteorological Watch Offices (MWOs) that issue SIGMETS, air traffic controls centres, flight dispatch 

centres, etc. To consolidate all the necessary monitoring and forecasting tasks into one place, a TCL 

based software known as the “Toolbox” was created which, since its inception, has undergone several 

revisions. It allows the on duty shift supervisor to continuously monitor various bulletins or pilot reports 

that may contain reference to volcanic ash and to track ash clouds with satellite data. The supervisor can 

also launch the CMC Trajectory Model and/or the CMC Canadian Emergency Response Model 

(CANERM) transport and dispersion Model. With the Toolbox, the results can be quickly posted on the 

public Montreal VAAC web-page or transmitted on national and international communications circuits 

as well as the WAFS. The toolbox also allows for the composition, transmission or re-transmission of 

volcanic ash advisory bulletins (FV). The latitude/longitude points of the ash cloud are extracted directly 

from the CANERM outputs with a few clicks of the mouse and automatically inserted in the FV, thus 

saving precious time. 
P4.4 

Session 4 – Page 55 

ERUPTION OF ANATAHAN VOLCANO: 

OPERATIONS AND OBSERVATIONS

Michael G. Middlebrooke 

NOAA/National Weather Service Forecast Office, Barrigada, Guam 

The first historic eruption of a volcano on the island of Anatahan, located in the Northern 

Mariana Islands in the western North Pacific Ocean, occurred on 10 May 2003 (Fig. 1, 

Fig. 2). Cooperation and coordination between the NOAA/National Weather Service 

Forecast Office on Guam, Washington VAAC, Saipan Emergency Management Office 

and the airlines were important for monitoring, processing and releasing information on 

the eruption. Imagery from polar-orbiting satellites proved to be an invaluable 

complement to imagery from the geostationary satellites for monitoring Anatahan’s ash 

plume (Figs 3, 4, 5, 6, and 7). 

Fig. 1 – Anatahan on May 11, 2003, the morning after the eruption began. This view is 

looking toward the southwest. The ash cloud reaches as high as 40,000 feet. 
Session 4 – Page 56 

Fig. 2 – View from NASA’s Terra satellite of Anatahan and its ash plume on May 11, 

2003. The upper-level plume brought volcanic haze aloft to the skies of Guam and Rota. 
Session 4 – Page 57 

Fig. 3 – GOES-9 visible image for May 22 at 2213 UTC (May 23 at 8:13 a.m. Guam 

time). The circulation around Typhoon Chan-hom has brought the plume south-southwest 

over Guam and Rota. On Guam, a light dusting of ash fell, and there was a strong smell 

of sulphur. Because of the ash, Continental Airlines canceled six flights into and out of 

Saipan. 
Session 4 – Page 58 

Fig. 4 – DMSP polar orbiter visible imagery showing the plume at 2034 UTC on May 23, 

2003 (6:34 a.m. on May 24 Guam time). Ash fell on Tinian and Saipan, again prompting 

the cancellation of flights to and from Tinian and Saipan. 
Session 4 – Page 59 

Fig. 5 – DMSP polar orbiter visible imagery from 2142 UTC on June 9, 2003 (7:42 a.m. 

on June 10 Guam time). In addition to the low-level ash/aerosol plume streaming west 

and northwest from Anatahan, volcanic smog or “vog” covers a large area further west. 

This vog is an aerosol that results from the chemical reaction between the volcano’s 

sulphurous gas emissions, oxygen, and atmospheric moisture. Note the shadows cast by 

towering cumulus clouds onto the vog layer below. 
Session 4 – Page 60 

Fig. 6 – DMSP polar orbiter visible imagery from 2226 UTC July 9, 2003 (8:26 a.m. July 

10 Guam time). The plume streams over 300 miles west from Anatahan. By this time, the 

plume is restricted to between the surface and about 8,000 feet, and it consists mostly of 

vog. The contrast in this image has been greatly enhanced to bring out the plume. Indeed, 

throughout July the plume was not visible in GOES-9 visible or IR imagery, and could 

only be seen under low sun-angle conditions by the DMSP satellite. 
Session 4 – Page 61 

Fig. 7 – In this DMSP polar orbiter visible image from 2100 UTC on July 18, 2003 

(7 a.m. Guam time on July 19), the vog plume is barely seen, even after greatly 

enhancing the image’s contrast. At this point, the plume was judged to consist solely of 

vog. As a result, volcanic ash SIGMETs on the plume were discontinued the following 

day. 
P4.5 

Session 4 – Page 63 

THE VOLCANIC ASH COLLABORATION TOOL (VACT) 

Jeffrey M. Osiensky, NWS Alaska Aviation Weather Unit, Anchorage, AK, USA 

Greg Pratt, NOAA Forecast Systems Laboratory, Boulder, CO, USA 

David J. Schneider, USGS Alaska Volcano Observatory, Anchorage, AK, USA 

Lynn Sherretz, NOAA Forecast Systems Laboratory, Boulder, CO, USA 

In order to facilitate real-time collaboration during North Pacific eruptions, a pilot project was instituted 

in 2003 to develop the Volcanic Ash Collaboration Tool (VACT). The VACT consists of workstations 

located at the Anchorage VAAC, the Anchorage Center Weather Service Unit, and the USGS Alaska 

Volcano Observatory, with shared access to satellite and meteorological data. The VACT allows for 

shared situational awareness by providing common views of the data sources, and by allowing all groups 

to view, enhance and annotate graphical data. This poster session will give participants the opportunity to 

gain hands-on experience with the VACT in order to explore its capabilities. 
P4.6 

Session 4 – Page 65 

VOLCANIC ASH MONITORING AND FORECASTING AT THE LONDON VAAC 

Sarah Watkin1

, Sigrún Karlsdóttir2, Nigel Gait1, Derrick Ryall1 & Helen Watkin1

1

Met Office, Exeter, U.K. 

2

Icelandic Meteorological Office, Reykjavik, Iceland 

Introduction to the London VAAC 

The London VAAC (Volcanic Ash Advisory 

Centre) is responsible for monitoring and 

forecasting the movement of volcanic ash over the 

United Kingdom, Iceland and the north-eastern 

part of the North Atlantic Ocean (Figure 1). 

Although this is a relatively small area, it covers 

some of the busiest airways in the world. A 

volcanic eruption on Iceland can quickly affect a 

large area of airspace, as strong winds spread the 

ash downwind from the volcano. Air traffic 

control organizations need to react quickly to the 

forecasts issued by the VAAC so that aircraft can 

be diverted onto alternative safe tracks. 

 Figure 1: The London VAAC area (on left) and the 

IOCA (on right in red). 

During a volcanic eruption on Iceland, the London 

VAAC liaises closely with forecasters at the 

Icelandic Meteorological Office (IMO), where 

monitoring of the Icelandic volcanic zone takes 

place. The London VAAC has access to the latest 

observational data as it emerges. This may be data 

from: seismic surveys, eye witness accounts (often 

from aircraft) of current plume behaviour or 

volcanic activity, or analysis of satellite pictures. 

During an eruption forecasters issue regularly 

updated Volcanic Ash Advisories Statements 

based on observational and forecast data about the 

current and predicted location of volcanic ash. 

Volcano monitoring at the Icelandic Met Office 

A volcanic eruption occurs in Iceland every four to 

five years on average. These eruptions can have a 

large impact on jet aircarft flying through the 

Icelandic Ocean Control Area (IOCA), which is 

one of the largest in the world (Figure 1). 

Approximately 250 jet planes cross the area daily 

and up to 500 utilize the area during favourable 

weather conditions (Sveinbjörnsson, 2001). 

A monitoring system (Stefánsson et al., 1993) 

covers the active volcanic zone in Iceland, and 

data from this system are analysed continuously 

by the IMO. Currently (in July 2004), two 

Icelandic volcanoes show signs of an impending 

eruption. Those are Mt. Katla (63°59’N, 

19°05’W), and Grímsvötn (64°41’N, 17°27’W). 

The last eruption of Mt. Katla was in 1918, hence 

a large eruption can be expected. Grímsvötn, on 

the other hand, erupted in 1998. In readiness for 

these eruptions, IMO receives two sets of images 

every day from the NAME model (see description 

below) run by the London VAAC. These images 

show the dispersal of volcanic plumes from 

hypothetical eruptions at the two locations, 

mentioned above (Figure 4). The height of the 

volcanic plume is an important input parameter 

into the model, and this information is based on 

research on previous eruptions at the same 

locations. This procedure makes it possible to 

issue a SIGMET indicating the forecast area of 

ash, only a few minutes after the onset of an 

eruption. Similar methods will take place when 

other volcanic areas show sign of impending 

eruptions. 

When an eruption occurs in Iceland the following 

working procedure takes place. At the start of the 

eruption IMO informs the Icelandic Civil Aviation 
Session 4 – Page 66 

Authorities and London VAAC about the eruption 

location and its estimated plume height. With this 

information the London VAAC calculates the 

spread of the plume with NAME, and the results 

are sent to IMO together with additional advisory 

information. During the eruption IMO and London 

VAAC forecasters monitor the volcanic plume via 

satellite images and with an Icelandic-based 

weather radar, which has shown to give valuable 

information (Lacasse et al., 2004) (Figure 2). 

Figure 2: C-band weather radar observations of the 

eruption plume from Mt. Hekla on 26 February 2000, 

approx. 11⁄2 hours after the start of the eruption, 

showing the estimated height of the eruption plume.

Eruption detection system 

The Met Office has developed an automatic 

volcanic eruption detection system using Meteosat 

infrared images and forecast meteorological data. 

The system uses a shape-matching technique to 

search for suspected volcanic eruption clouds in 

the London VAAC area each time a new satellite 

image becomes available (every quarter of an hour 

with MSG). 

Clouds are identified as possible ash clouds by 

checking for good correlation between the shape 

of the actual cloud and that which might be 

expected for an eruption cloud in the prevailing 

meteorological conditions. This shape is either 

circular, or a plume shape spreading downwind. 

The left image in Figure 3 shows the expected 

cloud shape that the system would have produced 

for Hekla at 1900Z on 26 February 2000 and used 

to search the image around Hekla for close shapematches. The right image shows the Meteosat 

infrared image at that time. The cloud would have 

been detected in the outlined position 40 minutes 

after the eruption began. 

Figure 3: Eruption of Hekla, Iceland on 26/02/00: the 

expected cloud shape produced by the detection system 

(left), would have detected the eruption in the 1900Z 

Meteosat IR image (right). 

 

The detection algorithm checks that the cloud that 

has been shape-matched exhibits other 

characteristics consistent with them being volcanic 

in origin: 

Location - cloud top should be close to a volcano, 

or downwind of a volcano. 

Contrast - cloud top brightness temperature should 

differ from the immediate surroundings. 

Height - the cloud top height should be at the same 

height as the wind used for establishing the shape 

and location conditions. 

In order to rule out as many false alarms as 

possible, the cloud must also pass the following 

checks to give sufficient confidence that it is not a 

meteorological cloud: 

Temporal check - the cloud was not present 

upwind of the volcano in a previous image. 

Grey level check - there are no other clouds in the 

vicinity at the same height. 

Sudden appearance check - the cloud has suddenly 

appeared in the image. 

Convective cloud check - no convective cloud has 

been forecast at that height. 
Session 4 – Page 67 

The eruption detection system detected 12 of the 

18 eruptions in the Meteosat field of view that 

were used to develop and test the system. The 

detection system was also tested on a month’s data 

in order to investigate how many false alarms 

would be produced. A false alarm is when the 

eruption detection system detects a candidate 

cloud that passes all of the tests, but no eruption 

had actually occurred. These results show that the 

system could monitor the London VAAC's area of 

responsibility with the production of only a few 

false alarms each day. During 2004 the system 

will be upgraded to use MSG images. The 

performance of the system will be re-evaluated 

and a decision made regarding possible 

operational implementation. 

Volcanic ash forecasting using NAME 

NAME is the Met Office's medium-to-long range 

atmospheric dispersion model. It has evolved into 

an all-purpose dispersion model capable of 

predicting the transport, transformation and 

deposition of a wide class of airborne materials, 

e.g. nuclear material, volcanic emissions, biomass 

smoke, chemical spills, Foot and Mouth disease. It 

is a Lagrangian particle dispersion model which 

predicts 3D concentrations and deposition of 

airborne particles and covers horizontal scales 

from ~1km to many 1000s km. It uses detailed 3D 

meteorology from the Met Office's Unified Model 

(horizontal resolution of 60 km globally and 12 

km over northwest Europe and the UK). 

During an eruption, forecasters run NAME to 

predict the dispersion of volcanic ash particles up 

to six days ahead. Where possible the plume 

height and release duration are derived from 

observations (e.g. satellite, radar or pilot reports). 

A release quantity of 1g ash is used (1g per six 

hour period if the eruption continues for more than 

six hours). A look up table based on summit and 

ash cloud height is used to determine the 

concentration corresponding to a 'visual ash cloud'. 

If good observational data is available then the 

release rate can be adjusted to provide a better 

match between observed and modelled visual ash 

clouds. An assumed particle size distribution is 

used, with a continuous distribution between 0.1-

50um. 

Figure 4: NAME forecasted dispersion for a 

hypothetical eruption of Mt. Grímsvötn. 

The output from NAME is a graphic showing the 

extent of the visible ash cloud at three levels: 

surface-FL200, FL200-FL350, FL350-FL550 for 

the next 24 hours at 6 hour intervals. More 

detailed plots are available to forecasters, 

representing concentration maps over 6 layers. 

The NAME forecast forms the basis of the 

volcanic ash advisory issued by forecasters. They 

are validated by comparison in real-time with 

satellite observations (see Figure 5 and the next 

section). In addition to using NAME during 

volcanic events, it is run twice daily, as mentioned 

above, to provide guidance to the IMO about the 
Session 4 – Page 68 

dispersion of ash from two volcanoes, Mt. Katla 

and Grímsvötn (Figure 4). 

There are several key modelling issues that 

remain. A clearer definition of a visual ash cloud 

is needed, along with a better understanding about 

what is hazardous to aircraft. Improved source 

terms are needed, particularly information about 

vertical extents and multiple or intermittent 

sources. Also, improvements in the NWP model 

that drives NAME in terms of the representation of 

orographic features are needed. 

Volcanic ash tracking using satellite data 

Once forecasters are notified about an eruption 

they need to track the transport of the ejected 

volcanic ash particles. Satellite observations offer 

the only possibility of tracking ash over large 

distances. However, discriminating between 

volcanic ash clouds and water or ice clouds can be 

difficult. The Met Office generates “volcanic ash 

images” routinely from Advanced Very High 

Resolution (AVHRR) data for regions covering 

the London VAAC area, Iceland and Mt. Etna 

(Watkin, 2003). These images are used by 

forecasters to discriminate between ash and 

water/ice clouds and enable them to track the ash 

and thus validate the NAME forecasts. The 

volcanic ash images show values of BT10.8 – 

BT12.0. In general: BT10.8 – BT12.0 < 0 for volcanic 

ash, BT10.8 – BT12.0 > 0 for water/ice clouds. 

These images have been used to study eruptions of 

Mt. Etna (there have been no Icelandic eruptions 

since their implementation in 2001). Figure 5 

shows AVHRR BT10.8 – BT12.0 images alongside 

NAME forecasts for two days during the eruption 

of Mt. Etna in 2002. This example demonstrates 

the usefulness of studying the two data sets in 

conjunction; e.g. the NAME forecasts confirm that 

the weak ash-signal (i.e. values are in a negative 

sense compared to surrounding clear-sky values) 

north-west of Sicily in the AVHRR image on 31 

October 2002 is volcanic ash. 

Meteosat-8 (Meteosat Second Generation) is a 

new geostationary satellite located at 0° longitude 

with a 15 minute imagery repeat cycle. The 

Spinning Enhanced Visible and Infrared Imager 

(SEVIRI) on board Meteosat-8 has 12 channels at: 

0.6, 0.8, 1.6, 3.9, 6.2, 7.3, 8.7, 9.7, 10.8, 12.0, 13.4 

μm and high resolution visible. Data from several 

of these channels could provide useful information 

about volcanic emissions (e.g. volcanic ash and 

sulphur dioxide). 

Currently, SEVIRI data are operationally received 

and processed to generate nowcasting products 

and imagery, including “volcanic ash images” 

(BT10.8 – BT12.0) every 15 minutes. The application 

of SEVIRI data offers a unique opportunity to 

advance satellite-based detection and retrieval of 

volcanic emissions. Work is underway to further 

exploit MSG data for volcanic emission 

monitoring. 

Summary 

The London VAAC provides a service to the 

aviation industry which advises about the presence 

of volcanic ash in a region encompassing Iceland, 

U.K. and the north-east Atlantic. To provide this 

service forecasters make use of a range of 

information: from the Icelandic Meteorological 

Office, from Icelandic radar, from NAME 

dispersion model forecasts and from satellite 

imagery. These information sources are supported 

by research into improving and extending the 

quality of the information. Research is currently 

underway in improving the NAME model for 

volcanic ash forecasting, in developing an eruption 

detection system and in the exploitation of 

Meteosat-8 (MSG) satellite data for volcanic ash 

and sulphur dioxide tracking. Close collaboration 

between the Icelandic Meteorological Office and 

the U.K. Met Office ensure that observational data 

about an eruption is transferred efficiently, that 

appropriate developmental work is undertaken and 

that Volcanic Ash Advisory Statements are timely 

and contain all available information. 
Session 4 – Page 69 

References 

Lacasse, C., Karlsdóttir, S., Larsen, G., Soosalu, H., 

Rose, W.I., and Ernst, G.G.J., 2004. Weather radar 

observations of the Hekla 2000 eruption cloud, Iceland. 

Bulletin of Volcanology, vol. 66, no. 5, pp. 457-473. 

Stefánsson R, Bödvarsson R, Slunga R, Einarsson P, 

Jakobsdóttir S, Bungum H, Gregersen S, Havskov J, 

Hjelme J, Korhonen H, Earthquake prediction research 

in the South Iceland Seismic Zone and the SIL project. 

Bull Seismol Soc Am 83: 696-716, 1993. 

Sveinbjörnsson M., Volcanic eruptions in Iceland: 

potential hazards and aviation safety. Unpublished MSc 

thesis, University of Iceland, 71 pp, 2001. 

Watkin, S.C., 2003: The application of AVHRR data 

for the detection of volcanic ash in a Volcanic Ash 

Advisory Centre. Meteorological Applications, 10, 301-

311. 

Figure 5: Eruption of Mt. Etna in October 2002. Top: AVHRR BT10.8 – BT12.0 images showing areas with negative 

values in red to yellow (indicating ash). Bottom: Forecasts from NAME showing show total column concentration (a 

continuous release rate of 0.278 mg/s from surface to FL200 was used). 

1200 UTC 28 October 2002

1316 UTC 28 October 2002 1008 UTC 31 October 2002

1200 UTC 31 October 2002
P4.7 

Session 4 – Page 71 

Web Access to the Digital Archive of VAA Messages and 

VAFTAD Model Output 

Paula Dunbar, National Geophysical Data Center, Boulder, Colorado, USA 

Grace Swanson, NOAA Satellite Services Division, Camp Springs, Maryland, USA 

To ensure safe navigation and monitor possible climatic impact, NOAA tracks volcanic ash 

eruptions throughout the world and monitors all available satellite images for ash clouds. After 

an eruption, NOAA issues a VAA message and a forecast of ash location in the atmosphere from 

the VAFTAD model. The National Geophysical Data Center (NGDC) has digitized and archived 

20 years of VAA messages, VAFTAD model output, and substantiating information for both 

foreign and domestic volcanoes issued by NOAA=s Volcanic Ash Advisory Centers (VAACs) 

and collected by the NESDIS Office of Satellite Data Processing Division (OSDPD). The 

substantiating information includes surface weather observations, pilot reports, volcanic 

observatory reports, news media reports, and satellite imagery for each event. During the next 

year these data will be input into a geospatially-enabled relational database management system 

(RDBMS) and made accessible over the Web. The database will also include links to GOES 

imagery from the CLASS GOES active archive. This database will provide researchers with 

access to all of the information concerning a past volcanic event, facilitating model evaluation. A 

prototype of the new website will be presented and comments and suggestions for improvement 

will be solicited. 

[This was given as an electronic poster.] 
5.1 

Session 5 – Page 1 

TECHNOLOGY TRANSFER: MOVING R&D TO OPERATIONS 

Steven R. Albersheim, Federal Aviation Administration 

Washington, DC, USA

Introduction 

The Federal Aviation Administration (FAA) under 

the new Air Traffic Organization (ATO) has adopted 

performance-based management of air traffic control 

system delivery of new technologies. FAA 

modernization projects are to “focus more on 

accountability and tracking costs related to service 

goals: and not change the technologies themselves.”1

 

To accomplish this, senior management, before 

committing resources to move a product into 

operations, requires a good sound business case to 

demonstrate how new products and services will 

improve efficiency and safety of the National 

Airspace System (NAS). Thus the best idea needs a 

path to implementation on an operational platform 

that can support goals in the Administrator’s Flight 

Plan 2004-2008. 

The Aviation Weather Technology Transfer (AWTT) 

process, established in 1999, supports the concept of 

developing a business case to move weather R&D 

products into operations. The AWTT process falls 

under the auspices of Air Traffic Operations Planning 

and is led by a governing board. Since, its inception 

it has evolved significantly and will continue to 

change to meet the operational needs of the new ATO 

Organization. 

The board is comprised of members that cut across 

FAA services and includes representation from NWS. 

The AWTT board encourages the development of 

new aviation weather products to improve the 

depiction and forecasting of weather events that 

affect not only the safety of the NAS but also the 

efficiency. This paper describes the functions of the 

board and the AWTT process. 

Functions of the AWTT Board

In 1999 FAA’s Air Traffic Requirements Services 

agreed that there was a need to have program to 

provide oversight on the transfer of new aviation 

weather products into operations. Products were 

being developed in the R&D community did not have 

a well-defined path to implementation on an 

operational platform. Having senior FAA and NWS 

managers on the AWTT Board brings together 

 

1

 “Setting up the ATO”, Development and Training News, 

FAA, Dec 5, 2003, www.ato.faa.gov. 

decision makers who can obligate the required 

resources to implement the product development onto 

operational platforms. 

In addition, the senior leaders on the Board provide 

direction to developers of new products on the needs 

for service that do not require major material 

procurement or in other words non-material 

solutions. For example, it has been recognized and 

widely accepted that weather is a major contributor to 

delays and accidents in the National Airspace System 

(NAS). Many of the solutions to mitigate weather 

impacts on operations are geared towards nonmaterial solutions. But for the most part many of the 

proposed changes in providing timely information on 

hazardous weather are software development issues 

using existing technology or platforms to display or 

provide a new or different product so decision 

makers have more timely and factual information on 

the hazardous weather. 

R&D to Operations—the AWTT Process 

Organizationally, the AWTT process is a four part 

series with four key decisions points, each requiring 

different input and supporting documentation. In 

some circumstances the information requested for the 

Board is a refinement or expansion of existing 

documentation to further embrace the development of 

the product. Figure 1 shows the conceptual process 

of the AWTT process. Under the auspices of the 

Board there is AWTT Steering Group (ASG) who 

serves as staff to the board. The ASG advises the 

Board members on the progress of the various 

programs that require the Board’s oversight. One key 

element that needs to be understood is that the 

AWTT oversees programs being supported by FAA’s 

R&D or Facility and Equipment (F&E) funds. The 

Board does not have authority to obligate funds. 

However, members to the Board who have 

operational platforms under their responsibility can 

thus plan accordingly to budget resources based on 

an agreed implementation plan. 

D1 Stage

The AWTT Board only becomes engaged in decision 

making for those actions that require a D3 or D4 

approval. For D1 and D2 actions the ASG has 

oversight and responsibility to ensure that the work 

being performed under R&D is in support of FAA 
Session 5 – Page 2 

mission and requirements to develop operational 

aviation weather products. Decisions approved at the 

D1 and D2 stage are approved jointly by first line 

managers in the respective Air Traffic Operations 

Planning, National Weather Service, and Flight 

Standards offices who serve on the ASG. Note that a 

D1 decision requires developers to have a sponsor to 

support the work they are performing. As part of that 

process a developer should be responding to a user 

needs assessment or analysis that provides direction 

on what is being requested in services but does not 

drive the solution. To further support a D1 decision 

an initial Concept of Use (ConUse) document should 

be prepared to describe conceptually how the product 

would be used in operations or meet a stated goal or 

requirements. By necessity, this initial ConUse will 

be general and flexible enough to accommodate 

changes in direction of the research as opportunities 

arise. 

D2 Stage

A D2 decision by the ASG allows the developer to 

move from a concept to a product that needs to be 

tested in a lab or simulated environment. The 

product may remain in the D2 stage for several years 

until the developer believes that the product is ready 

for advancement. The ASG does not have direct 

input during this process but should be kept informed 

of the work that is under progress and be consulted 

on a periodic basis to help support the continuation of 

this work during situations that may require 

budgetary support. 

D3 Stage

When entering a D3 decision, the Board is requested 

to convene and make a determination that the 

proposed product is ready for experimental testing. 

This is a critical stage in that the FAA is sanctioning 

the potential use of the product. Crucial to obtaining 

Board approval is the preparation of a detailed 

ConUse plan. Table 1 provides an outline of what is 

to be included in a ConUse plan. Even though the 

product is still in an experimental stage the 

developer, in consultation with the users, should have 

a clear consensus and understanding of how the 

product is to be used in operations for the purpose of 

the testing. This understanding then leads to the need 

to develop a detailed test plan that will demonstrate 

how the product can be accessed, used, and verified. 

Included in the test plan is the need to develop a 

metric or standard to measure against the success of 

the product. Quite often the minimum for success is 

that the product does no worse than existing 

capabilities; however, under today’s austere budgets 

developers need to set higher standards of success if 

the Board is to agree that a product is beneficial to 

users of the NAS. Another requirement is an initial 

scientific/technical review. A favorable conclusion 

on the scientific merits of the project helps show that 

the product shows promise, though it may need 

further refinement. The goal in this evaluation 

process is to facilitate the weeding out of any 

proposed products that may not be based on sound 

scientific principles or that appear to have no 

potential for future maturation. 

Also, this D3 stage is critical because it begins the 

process for requesting an Operational and 

Maintenance (O&M) budget with the anticipation 

that the product will be operational on a FAA 

platform for a defined out year. It also further 

defines whether there is need to enter the FAA 

Acquisition Management System (AMS) process that 

requires the development of a mission needs analysis 

and other supporting documents. Most important and 

critical at this stage is obtaining concurrence from 

FAA’s Flight Standards Service before being 

released to a controlled test group where it can be 

displayed on a sanctioned FAA test bed such as the 

NWS Aviation Weather Center Aviation Digital Data 

Server (ADDS). As part of this approval process the 

developers are required to prepare and present a test 

plan that describes the objectives of the project, how 

the testing will be conducted and how the test 

supports the ConUse. In addition, an initial 

Implementation Plan (IP) is written to detail tasks 

each responsible organization must accomplish to 

ensure smooth transition through the experimental 

applications stage into operational implementation. 

The IP includes, among other issues, actions on 

system architecture, product integration, training, and 

labor-management relations. 

D4 Stage

Once a product has completed its experimental 

testing it can be considered ready for a D4 decision. 

In this stage, a final ConUse is written to describe 

how the product will be used in an operational 

environment. Included in this ConUse is direction to 

change other supporting documents on the use of the 

product such as the Airmen Information Manual 

(AIM), and further refinement of risks and benefits. 

In addition, the product has undergone more 

intensive scientific/technical review and has been 

judged as technically valid and scientifically sound. 

The sole basis for the technical review panel 

conclusion is the scientific and technical validity of 

the product. The technical review panel does not 

consider operational utility and human factors 
Session 5 – Page 3 

qualities, which are evaluated separately with the end 

users. 

Also, if all goes as planned there should be an O&M 

budget in place to transition the product into an 

operational environment. To ensure that the product 

can be advanced to operational a D4 decision 

requires an implementation plan. The plan identifies 

the responsibilities of various services to ensure that 

the product can be operational on the agreed too 

implementation date. Critical to the implementation 

plan is the identification of users and platforms that 

product is to be made available to. Funding is more 

forth coming from the FAA to further advance this 

project as in this stage a more refined con use 

emerges and risks have been identified with the 

possibility of success. 

Public involvement

The proceeding sections described the boxes that had 

to be checked to move through each stage to the end 

state. Critical to meeting the requirements for Stages 

3 and 4 is public involvement. The FAA has learned 

that public user input is key to the success to the 

deployment of any new product. Without customer 

acceptance of the new product it will never succeed. 

Not to be forgotten are the FAA’s bargaining units. 

Their input is solicited and critical to any successful 

deployment of a new product. Implementation of any 

new product on an operational platform requires 

procedures and training. 

Obtaining customer input and addressing bargaining 

units concerns can be a formidable challenge at 

times. As a means to gather public input the FAA 

conducts quarterly public meetings to solicit input 

from the public by reviewing the status of various 

programs, discussing a roadmap to implementation 

and allowing users to interact with the developers. 

During the public discussion the FAA describes the 

attributes of the product and describes how it will be 

used in the NAS. It should not be assumed that a 

product will be given carte blanche approval for use 

by all users of the NAS. Experience has shown that 

many of the new products and innovations are not 

ready for stand-alone operation to replace existing 

hazardous messages. On the other hand these new 

products are used to supplement existing capabilities 

or can be used as guidance for input to the official 

hazardous message. The eventual end stage is to 

develop products that have greater capability to 

provide timely and more accurate information than 

existing messages, but the FAA deems it useful to 

phase in products when it believes there is value 

added to the services. Bargaining units issues are 

addressed separately but at the end all significant 

issues have to be addressed and resolved for both the 

public and the bargaining units. 

 

Conclusion 

The FAA has established a process that helps to 

accelerate the transfer of technology into operations. 

At the present time the FAA is further refining its 

management and oversight of this approach. New 

products bring new challenges that must be resolved 

before they can be approved in an experimental and 

operational mode. The FAA needs to ensure that the 

information being provided is not misleading and that 

those users who may be participating in an 

experimental phase or plan on using the product to 

support operational decisions fully understand the 

attributes of the product and information being 

provided. 
Session 5 – Page 4 

Table 1 Guidelines for Con Use Plans to support 

Experimental or Operational Decisions for the 

AWTT Board 

1. Introduction 

1.1. Purpose 

1.2. Drivers 

2. Description of the Need 

3. Description of the Product 

3.1. Technical Description 

3.2. How New Product/Capability Address 

Shortfalls 

3.3. Product Output 

3.4. Regulatory Impact 

3.5. Relationship to Other Domestic or 

International Products 

4. Product Usage 

4.1. Impact of New Product/Capability on 

Operations 

4.2. Accessibility 

4.3. Limitations 

4.4. Training 

5. Evolution of the Product 

5.1. Replacement and Changes 

6. Performance, Benefits and Costs 

6.1. Performance Metrics 

6.1.1. Description of how to measure 

"goodness" of the product 

6.1.2. Criteria for success 

6.1.3. Technical performance standards 

6.2. Description of the Benefits 

6.2.1. Benefits of Using the Product 

6.2.2. Impact of Not Implementing the 

Product 

6.3. Description of the Costs 

6.3.1. Budget Impacts 

6.3.2. Other Costs 

6.3.3. Who pays? 
Session 5 – Page 5 

• These product improvements are not currently under the AWTT process 

Figure 1. Aviation Weather Technology Transfer (AWTT) process, showing major milestones and key tasks associated with each milestone.
5.2 

Session 5 – Page 7 

 EFFECTS OF VOLCANIC ACTIVITY ON AIRPORTS 

Marianne Guffanti, U.S. Geological Survey, Reston VA, USA 

Gari C. Mayberry, U.S. Geological Survey, Washington DC 20560, USA 

Richard Wunderman, Smithsonian Institution, Washington DC 20560, USA 

Thomas J. Casadevall, U.S. Geological Survey, Denver CO 80225, USA 

Introduction

In addition to posing a hazard to in-flight 

aircraft from airborne volcanic ash, volcanic activity 

also can disrupt operations at airports, with both local 

and global consequences for modern life and 

commerce. Worldwide, approximately 500 airports 

lie within 100 km of volcanoes that have erupted 

since 1900 AD. The primary volcanic hazard to 

airports is ashfall, which causes loss of visibility, 

structural damage, contamination of ground systems 

and parked aircraft, and slippery runways. 

Temporary airport closures have resulted from 

accumulation of just a few millimeters of ash. On 

rare occasions, airports also have been damaged by 

pyroclastic flows (e.g., on the island of Montserrat, 

British West Indies, in 1997) and lava flows (notably, 

at Goma, Dem. Rep. of Congo, in 2002). Ash in 

airspace around airports has damaged in-flight 

aircraft (e.g., near Guatemala City, Guatemala, in 

1999), and airport closures may involve loss of 

alternate landing sites required for operation of longdistance twin-engine flights (particularly for flights 

over the North Atlantic). 

Ash-contaminated airports can operate with 

due caution. Practical operational guidelines, based 

on experience at numerous airports, have been 

published by ICAO (International Civil Aviation 

Organization, 2001) and the U.S. Geological Survey 

(Casadevall, 1993). At-risk airports should have such 

information on hand as a basic preparedness measure 

and consider developing operational plans for ashfall 

events. 

Extent of the Volcanic Hazard to Airports

Airport and volcanic data collected by the 

U.S. Geological Survey’s Volcano Hazards Program 

and the Smithsonian Institution’s Global Volcanism 

Program illustrates the extent of the volcanic hazard 

to airports. Information about reported instances of 

airports affected by volcanic activity was gleaned 

from various sources, including news outlets, 

volcanological reports (particularly the Smithsonian 

Bulletin of the Global Volcanism Network), and 

previous publications on the topic (e.g., Casadevall, 

1993). For each instance, information about the 

airport (such as latitude, longitude, country) and a 

brief description of the operational disruption have 

been compiled along with data on the volcanic source 

(such as latitude, longitude, eruption date, volcanic 

explosivity index). 

Analysis of the resulting database reveals that 

from 1944 through 2003, operations at airports in at 

least 75 cities, towns, and military bases in 20 

countries (Table 1) were disrupted on 108 occasions 

by eruptions at 34 volcanoes. This is not a complete 

inventory of airport disruptions because incidents are 

not always reported; nevertheless, it is a good sample 

from diverse parts of the world. About 50% of the 

impacted airports are located within 100 km of the 

source volcano, but operations at airports as far away 

as 500 to 1700 km from the eruptive sources have 

been disrupted. Some airports have been affected 

repeatedly – viz., at Anchorage in the USA, Bramble 

(now destroyed) on Montserrat, Catania in Italy, 

Guatemala City in Guatemala, Kagoshima City in 

Japan, Mexico City in Mexico, Quito in Ecuador, and 

San Juan in Puerto Rico. 

The 34 source volcanoes are in 14 countries 

(Table 2). The volcanoes that most often disrupt 

airports are Mount Etna in Italy, Sakura-jima in 

Japan, Popocatepetl in Mexico, and Soufriere Hills on 

the Island of Montserrat in the British West Indies. 

Soufriere Hills Volcano, although the source of 

relatively small ash clouds since 1995, has affected 

the most airports (11), which is not surprising given 

its proximity to many other islands with airports. 

Indonesia and the United States have the most 

volcanoes (5 each) reported to have caused airport 

disruptions. 

An important factor in determining whether 

an eruption will affect a specific airport is the wind 

field at the time of eruption. For example, the 
Session 5 – Page 8 

prevailing winds in the Pacific over the Mariana 

Islands blow predominantly but not exclusively 

toward the west, and during most of the May-July 

2003 eruption of Anatahan Volcano ash was 

dispersed away from population centers lying south 

of the volcano. But on 23 May 2003, winds from 

Typhoon Chan-Hom pushed the ash plume 

southward, dusting Saipan and causing flight 

cancellations there and at Guam, 320 km south of the 

volcano. 

Reducing Operational Disruptions

With some forewarning of imminent volcanic 

hazards and an operational plan for ash events in 

hand, a vulnerable airport can take measures to 

mitigate the disruptive effects of ashfall. Such 

measures include conducting cleanup quickly and 

efficiently, moving or covering parked aircraft, 

optimizing runway usage, and reducing closure time. 

Recommended clean-up procedures and other 

mitigation actions are summarized online at: 

http://volcanoes.usgs.gov/ash/trans/index.html

Methods of forewarning of volcanic activity 

that have been used by airports include: (1) realtime detection of explosive volcanic activity; (2) 

forecasts of ash-plume paths; and (3) detection of 

approaching ash plumes using ground-based 

Doppler RADAR. 

Real-time detection of explosive volcanic 

activity at Sakura-jima Volcano, Japan, allows use of 

the nearby airport in Kagoshima City despite the 

volcano’s frequent eruptions (>7,300 eruptive events 

since 1955). Eruptive phenomena are monitored 

around the clock and in all weather conditions with 

continuously transmitting seismic and infrasonic 

instruments designed to distinguish explosive, ashproducing eruptions from volcanic earthquakes and 

tremor without ash production. When the monitoring 

system detects an explosive eruption, a warning is 

automatically sent to flight dispatchers at Kagoshima 

International Airport. Dispatchers then check wind 

data and visibility and rapidly issue a 

recommendation to pilots (e.g., divert to another 

airport, maintain holding position, select alternate 

arrival route, or select normal arrival route). The 

monitoring/warning system used at Sakura-jima has 

proven very effective at reducing risks to aviation in 

an unfavorable volcanic environment (Onodera and 

Kamo, 1994). 

Forecasts of ash-plume paths, based on ashtrajectory models for eruptions from proximal 

volcanoes, provided valuable forewarning to airport 

operators and the airline industry during the 1989-

1990 eruption of Redoubt Volcano in Alaska (Murray 

and others, 1994). The Alaska Volcano Observatory 

(AVO) and the Anchorage Weather Service Forecast 

Office adapted a NOAA model that predicted plume 

trajectories for 3-hr intervals based on forecast wind 

fields. Before an eruption, the model was used to 

estimate where and when ash would be blown. Twice 

daily, after the predicted wind fields were updated, 

AVO would plot the trajectories predicted for the 

next 72 hours. These trajectories were on hand when 

an eruptive event occurred and were distributed by 

fax to all interested parties who could then act 

accordingly to mitigate the effects of volcanic ash. 

For example, Anchorage airports could optimize the 

times that runways were kept open. In general for 

airport needs, ash-dispersion and trajectory models 

should have the capability to: indicate where ash 

would go in the first one to two hours after an 

eruption; estimate arrival time of ash at a particular 

location in addition to estimating ashfall thickness; 

and deal with small- to moderate-sized recurring 

eruptions with little ashfall as well as major ashproducing events. 

Detection of approaching ash plumes using 

ground-based Doppler RADAR was applied in 

Mexico City, located about 60 km from 

Popocatepetl’s summit and within the volcano’s ashhazard zone. In 1997, Mexico’s National Center for 

the Prevention of Disasters (CENAPRED) and the 

U.S. Geological Survey used an experimental groundbased Doppler RADAR to track the direction and 

speed of ash plumes, especially when visual 

confirmation was difficult at night and in bad weather 

(Hoblitt and Quaas Weppen, 1999). When the 

combination of seismic and RADAR data confirmed 

an eruption had occurred, alerts were given to airtraffic controllers at Mexico City International 

Airport to prevent encounters of aircraft with ash 

around the airport. The experimental system used in 

Mexico eventually suffered a hardware failure, and 

development of a robust system is needed for further 

volcanic applications. 

Conclusions

Given the demonstrated vulnerability of 

airports to disruption from volcanic activity, 

vulnerable airports should have basic preparedness 

information on hand, evaluate appropriate systems 

that can provide forewarning of imminent volcanic-
Session 5 – Page 9 

ash hazards, and develop operational plans for 

ashfall events. Such a plan describes: methods and 

available equipment for clean-up, procedures for 

incorporating up-to-date information from a 

volcanological agency about eruptive activity from 

the proximal volcano(es) into operational decisions, 

protocols for making the decision to close an airport 

to ensure aircraft and passenger safety, and 

procedures for managing air traffic in ashcontaminated airspace in the vicinity of the airspace. 

References Cited

Casadevall, T. J., 1993, Volcanic Ash and Airports – 

Discussion and Recommendations from the 

Workshop on Impacts of Volcanic Ash on 

Airport Facilities: U.S. Geological Survey OpenFile Report 93-518, 52 pp. 

Hoblitt, R.P., and Quaas Weppen, R., 1999, Doppler 

radar as a volcano monitoring tool [abstract.]: 

International Symposium on Popocatepetl 

volcano, 22-24 March, 1999, Mexico City, p. 

19. 

International Civil Aviation Organization, 2001, 

Manual on Volcanic Ash, Radioactive Material, 

and Toxic Chemical Clouds: Doc 9691-AN/954. 

Murray, T.L., Bauer, C. I., and Paskievitch, J., F., 

1994, Using a personal computer to obtain 

predicted plume trajectories during the 1989-

1990 eruption of Redoubt Volcano Alaska: U.S. 

Geological Survey Bulletin 2047, p. 253-256. 

Onodera, S., and Kamo, K., 1994, Aviation safety 

measures for ash clouds in Japan and the system 

of Japan Air Lines for monitoring eruptions at 

Sakurajima Volcano: U.S. Geological Survey 

Bulletin 2047, p. 213-219. 

Table 1. List of cities, towns, and military bases in 

which airport operations were disrupted by volcanic 

activity, 1944 through 2003, organized by country. 

________________________________________

Antigua

 Saint John’s 

Argentina

Buenos Aires, Comodoro Rivadavia, Cordoba, 

Jujuy, Mar del Plata, Neuquen, Puerto 

Deseado, San Julian, Salta 

Colombia

 Pasto 

Dem. Rep. of Congo

 Goma 

Dominica

 Roseau 

Ecuador

 Ambato, Cuenca, Guayaquil, Quito, Riobamba 

France

 Unnamed airport(s) on Guadeloupe 

Guatemala

 Guatemala City 

Indonesia

Bandung, Gorontola, Manado, Medan, 

Surabaya, Unnamed airport west of Gamalama 

volcano 

Italy

 Catania, Reggio di Calabria, Naples, Sigonella 

Naval Air Station 

Japan

 Kagoshima, Mijake-jima 

Mexico

 Colima, Mexico City, Puebla, Unnamed airports 

in SE Mexico 

Netherland Antilles

 Sint Maarten 

New Zealand

 Auckland, Tauranga 

Paraguay

 Asuncion 

Philippines

Basa Air Base, Clark Field, Cubi Point, Legaspi, 

Manila, Puerto Princesa, Sangley Pt. Air Base 

Papua New Guinea

 Kimbe, Kavieng, Port Moresby, Rabaul 

St. Kitts

 Unnamed airport 

United Kingdom

Unnamed airport on Anguilla, Bramble 

(Montserrat), Stanley (Falkland Islands) 

USA and Territories

Anchorage, Elemendorf Air Force Base, Grant 

County, Guam, Kenai, Merrill Field, Missoula, 

Portland area, Pullman, Roosevelt Roads Naval 

Air Station (Puerto Rico), Saipan (Mariana 

Islands), San Juan (Puerto Rico), St. Croix (US 

Virgin Islands), St. Thomas (US Virgin 

Islands), Spokane, Unnamed airports on south 

Texas coast, Yakima 
Session 5 – Page 10 

Table 2. Volcanoes whose eruptions are known to 

have caused operational disruptions at airports, 

1944 through 2003, organized by country. 

________________________________________

Chile

Hudson, Llaima, Lascar 

Colombi

Galeras 

Democratic Republic of the Congo

Nyiragongo 

Ecuador

Guagua Pinchincha, Reventador, Tungurahua 

Guatemala

Fuego, Pacaya 

Indonesia

Agung, Galunggung, Gamalama, Lokon, 

Soputan 

Italy

Etna, Vesuvius 

Japan

Miyake-jima, Sakura-jima 

Mexico

El Chichon, Colima, Popocatepetl 

New Zealand

Ruapehu, White Island 

Papua New Guinea

Lamington, Pago, Rabaul 

Philippines

Pinatubo 

United Kingdom

Soufriere Hills (Montserrat) 

USA and Territories

Augustine, Redoubt, Spurr, St. Helens, 

Anatahan (Mariana Islands) 
5.3 

Session 5 – Page 11 

AN AIR TRAFFIC CONTROL PERSPECTIVE ON VOLCANIC ASH: 

HOW TO DEAL WITH IT 

Richard Hernandez, FAA San Juan Automated International Flight Service Station 

Puerto Rico, USA 

The majority of the air traffic controllers in the 

National Airspace System have limited or no 

experience in controlling traffic when there is 

volcanic ash. Although controllers who work 

specifically at San Juan have little knowledge of 

the affects of volcanic ash, they have to deal with 

this hazard on a routine basis. 

 This paper will discuss the weather issues 

associated with ash from the Soufreire Hills 

volcano located on the island of Montserrat and 

provide a historical overview of how it affects 

aviation airways in the San Juan airspace. 

 The two most important factors in 

determining volcanic ash are forecasting and 

observations. Within the Federal Aviation 

Administration, three specific organizations 

collect volcanic ash information, the towers, the 

centers, and the flight service stations. Pilot 

reports are the name given to the collected 

weather observations by airborne aircraft. The 

function of the flight service station is to receive 

pilot reports and disseminate the information to its 

users. The goal of the flight service station is to 

keep everyone informed expeditiously. The 

aviation industry and the flight service station are 

the other eyes and ears of the National Weather 

Service. After pilot reports are processed, they 

are issued to the National Weather Service and 

other concerned agencies. Whereas the purpose 

of forecasting is to predict, the purpose of 

observations is to verify. Whenever mid-level 

clouds block satellite imagery, the use of pilot 

report enhances forecasting. There are occasions 

when pilot reports do not conform to the 

forecasted models. Weather information received 

from the flight service station is trustworthy for all 

types of pilot reports. 

 Puerto Rico the smallest of the Greater 

Antilles is located 350 nautical miles northwest of 

the island of Montserrat. This geographical 

position places it in the direct path of volcanic 

ash. In addition, St. Croix, the southern most of 

the U. S. Virgin Islands and the Puerto Rico 

municipal islands of Vieques and Culebra located 

on the east and southeast coast of Puerto Rico are 

also in the direct path of volcanic ash. 

WEATHER ISSUES ASSOCIATED WITH 

VOLCANIC ASH 

 The determining factors for the movement 

of volcanic ash are the atmospheric conditions 

that surround it. 

 Historically, volcanic ash creates an 

aviation hazard at both the lower and upper 

altitudes. Surface high pressure over the Atlantic 

will generate a southeast wind component that can 

lift volcanic ash to about 10,000 feet and move it 

in a northwesterly trajectory. The normal trade 

wind flow will usually keep volcanic ash within 

the airspace of the Lesser Antilles. However, any 

changes to the position of the high pressure will 

change the prevailing direction of the wind. 

When the pressure gradient generates moderate to 

strong southeasterly winds, it can act as the 

medium for pushing volcanic ash into the San 

Juan airspace. Anytime the low-level winds are 

from the southeast, volcanic ash can carry into 

Puerto Rico. 

 As volcanic ash lifts into the upper 

atmosphere, other factors influence its movement. 

Sub tropical jet stream currents, upper level 

westerly winds and upper level troughs with an 

axis over Puerto Rico and a southwest flow aloft; 

can induce volcanic ash into the Atlantic and 

away from aviation airways. The result is that 

weather systems in the Caribbean and their 

movement greatly influence aviation in the San 

Juan and the Lesser Antilles airspace. 

 From Puerto Rico, the principal airways 

into the Caribbean are to the southeast and into 

the path of volcanic ash. Consequently, all facets 

of the air traffic system are equally impacted. 

The affects of volcanic ash on aviation in the San 

Juan airspace – 
Session 5 – Page 12 

FROM THE VIEWPOINT OF THE AIR 

TRAFFIC CONTROL CENTER 

1. Availability of altitudes – because of the 

different types of aircraft characteristics, not all 

aircraft can fly above the tops of volcanic ash. 

2. Availability of airspace – volcanic ash affects 

navigational routes causing aircraft to fly around 

airspace with hazardous weather. 

3. Lack of pilot reports – pilots are not sharing 

information in a timely manner so that other 

aircraft entering the affected airspace can plan 

accordingly. 

4. Wastes of fuel – The routing of aircraft away 

from hazardous weather, will always incur the 

cost of extra fuel consumption. This, in turn, can 

lead to prioritizing aircraft out of sequence for 

arrival due to their fuel being below minimums. 

5. Increase controller workload – aircraft that are 

in volcanic ash increase the workload at the 

adjacent control sectors. Controllers have to 

transition aircraft safely away from adverse 

weather. 

6. Arrivals and departures delays – arrivals and 

departures become late in order to compensate for 

aircraft saturation in the different control sectors. 

FROM THE VIEWPOINT OF THE FLIGHT 

SERVICE STATION 

1. Pilot weather briefings increase – whenever 

there is an aviation weather hazard, all aviation 

interest including the ports authority request the 

latest and most current information. 

2. Keeping the air traffic center updated – 

updates on weather advisories and pilot reports 

need to be timely and current. 

3. Weather advisories – the receipt of significant 

weather advisories from the adjacent 

meteorological providers are either late or nonexistent. 

FROM THE VIEWPOINT OF THE AIR 

TRAFFIC CONTROL TOWER 

1. Lack of knowledge - The lack of training and 

familiarization by general aviation limits their 

capacity to manage effectively the affects of 

volcanic ash on engine intake. The Federal 

Aviation Administration strongly recommends 

aircraft not to depart when there is the presence of 

volcanic ash 

2. Engine intake - The possibility of engine intake 

from volcanic ash can greatly reduce aircraft 

mobility at the airport. 

3. Pilot reports – The system users need to be 

more responsible and comply with request for 

pilot reports. 

4. Aircraft scheduling - Airlines have the 

authority to determine aircraft scheduling. 

However, the lack of timely pilot reports and 

weather advisories makes it difficult to determine 

if the aviation hazard is either haze or volcanic 

ash. 

5. Availability of gates – Scheduling also affects 

the availability of gates and create saturation by 

reducing the number of spaces open to parking. 

6. Increase workload – When aviation hazards are 

lifted traffic on the ground increases. General 

aviation will tend to call the tower for volcanic 

ash information when they should be calling the 

flight service station for a proper weather briefing. 

7. Reporting training disagreement – There have 

been instances where observers and the National 

Weather Service have reported volcanic ash or 

haze or a combination of both. Tower personnel 

have requested training to help them visibly 

identify and distinguish what is haze and what is 

volcanic ash. 
Session 5 – Page 13 

FROM THE VIEWPOINT OF THE PORTS 

AUTHORITY 

1. Breaking action of aircraft – Volcanic ash on 

the runway limits the breaking action of aircraft. 

In addition, the presence of precipitation mixed 

with volcanic ash creates a soapy substance and 

affects the runway drainage system. The outcome 

is that the runway has to be re-grooved. 

2. Temperature variation – Because of the airport 

proximity to water there is a temperature variation 

between the surrounding land area, the runway, 

and the water. Wind direction can create a vortex 

that causes an uneven displacement of volcanic 

ash. Uneven accumulation of volcanic ash caused 

by a microburst can also affect the breaking action 

of aircraft. 

3. Aircraft and airport equipment - Because 

volcanic ash is an abrasive, corrosion acts upon 

the movement of aircraft and airport equipment. 

4. Reduced visibility - volcanic ash affects the 

airport lighting system reducing visibility. 

5. The need for a letter of agreement - No joint 

letter of agreement exists between the National 

Weather Service, the flight service station, and the 

tower to keep the ports authority informed in a 

timely manner of aviation hazards. 

6. Health hazard - in addition to an aviation 

hazard, volcanic ash is also a health hazard. 

Several employees at both the tower and the ports 

authority have complained that the presence of 

volcanic ash has caused bronchial asthma, 

sinusitis and respiratory ailments. 

 
5.4 

Session 5 – Page 15 

THE NEW ZEALAND VOLCANIC ASH ADVISORY SYSTEM 

Peter Lechner 

Civil Aviation Authority of New Zealand, Lower Hutt, New Zealand 

1. INTRODUCTION 

The Civil Aviation Authority of New Zealand (CAA) 

now recognise the New Zealand civil aviation industry’s 

ability to manage it’s operations in proximity to 

volcanic ash with the aid of accepted civil aviation 

procedures and new information flow systems described 

in this paper. The Volcanic Ash Advisory System 

(NZVAAS) is primarily provided through the 

interactions of aircraft operators, Airways Corporation 

of New Zealand (ACNZ) and Meteorological Service of 

New Zealand (MetService). There is also important 

ground based volcanic information input from the 

Institute of Geological and Nuclear Sciences (IGNS). 

The CAA no longer takes any part in the provision of 

operational volcanic ash information; however, it does 

continue to promote awareness of the NZVAAS and an 

understanding of the volcanic ash threat to civil aviation 

in New Zealand. 

This paper is intended to illustrate the relationships 

between the NZVAAS participating agencies and show 

their various obligations in providing enhanced volcanic 

ash information to the civil aviation industry. In doing 

so it sets out supplementary procedures to the accepted 

ICAO practices, in particular the International Airways 

Volcanic Watch (IAVW) and Volcanic Ash Advisory 

Centre (VAAC) obligations and responsibilities. 

2. DEVELOPMENT BACKGROUND 

The volcanic activity of Mt Ruapehu had a significant 

impact on civil aviation in New Zealand during 1995 

and 1996. Many flights were cancelled and many more 

diverted or re-routed. These episodes were the first time 

volcanic ash has impacted on modern aviation in New 

Zealand. New Zealand has a number of active 

volcanoes on or near the mainland and a number of 

volcanoes within its IAVW area of obligation. 

The CAA operated a special Volcanic Ash Watch 

Office throughout the 1995/6 periods of volcanic 

activity at Mt Ruapehu. The Office’s prime task was to 

manage volcanic ash affected airspace, restricted and 

danger areas, through the issue of formal Notices to 

Aviation (NOTAM). 

A CAA and airline industry fact-finding team went to 

North America in July/August 1996 where it sought 

advice on ways of operating aircraft near volcanic ash 

with minimum disruption. It was widely accepted that 

there was an increasing risk to aviation worldwide from 

the ejection of volcanic ash into the atmosphere. As a 

result of the fact-finding team's report, the way that ash 

affected airspace was managed and the type and volume 

of information available on that airspace was reviewed. 

The main issues to safely allow civil aviation to 

continue in proximity to volcanic ash were; ownership 

of the advisory system, improving alerts, improved 

tracking and drift prediction, airline discretion, 

contingent airspace management, operational 

communications and on-going education. 

Work has continued in New Zealand to address these 

issues including: awareness promotion articles and 

posters printed and distributed by the CAA; 

incorporation by airlines of procedures to routinely 

report volcanic and ash activity using the standard 

Volcanic Ash Report (VAR) forms and procedures; 

improved ground based monitoring of volcanoes and 

implementation of alert paging systems linked to 

seismic monitoring equipment by IGNS; MetService 

has reviewed and strengthened its production of 

volcanic ash warnings (SIGMET) and its use of ash 

trajectory and dispersion models and ACNZ has set up a 

system to manage alternative routes affected by 

volcanic ash and implemented a CAA defined set of 

standard, ready to use, Volcanic Hazard Zone NOTAM. 

Success in reducing the disruptive effects of ash on 

aviation is determined by information on the eruptions 

and the communication of relevant information to all 

interested parties. The NZVAAS primarily 

contemplates the three most risky volcanoes; Ruapehu, 

Ngauruhoe and White Island and takes into account 

other volcanoes in New Zealand. 

3. THE MAIN VOLCANOES 

New Zealand has a number of volcanoes, each with its 

own eruptive characteristics. Scientific study indicates 

that the majority must be considered as dormant, rather 

than extinct, and that they will produce eruptions at 

some indeterminate time in the future. New Zealand 

volcanoes can be classed as those that are frequently 

active or reawakening and those that are not. The cone 

volcanoes Ruapehu, White Island and Ngauruhoe are 

classified as frequently active and pose a real threat to 

aviation in New Zealand. Prior to any eruption, physical 
Session 5 – Page 16 

precursors are expected to be identifiable; these may 

develop over time frames of days (and possibly only 

hours) for the basaltic sites, over months for andesitic 

sites, and over years for the rhyolitic sites. Such 

precursors provide the basis for the formulation and 

issue of warning information. 

A volcanic eruption will produce a number of hazards, 

including ash that will have an effect on hundreds of 

kilometres of airspace. A volcanic event may build up 

over weeks to years and be relatively difficult to predict 

in its probable course and timing. However, ash ejected 

into the atmosphere can be tracked and its course 

predicted using conventional and developing 

meteorological methods. There is therefore a need for 

flexibility when undertaking volcanic planning. How 

these issues are managed can depend upon the known 

characteristics of each volcano, the amount of ash 

ejected and the prevailing conditions at the time of, or 

during, the event. 

4. VOLCANO ALERT LEVEL 

Ongoing volcano surveillance enables the background, 

or normal status, of a volcano or volcanic field to be 

determined. Variations of monitored parameters may 

indicate a change of status and the onset of an eruptive 

episode. An assigned ‘Scientific Alert Level’ defines 

the status of a volcano at any given time. Table 1 sets 

out the Scientific Alert Level criteria. 

The New Zealand Volcano Scientific Alert Levels are 

based on a six-level system, with each level defining a 

change of status at the volcano or field. The lowest level 

(dormancy) is signified by ‘0’ and the highest (large 

hazardous eruption) by ‘5’. The scale or size of an event 

will vary from volcano to volcano, ie; a Level ‘3’ event 

at Ruapehu will be larger than a Level ‘3’ at 

Ngauruhoe. Where information from the IGNS volcano 

surveillance programme indicates a change in a 

volcano’s status (either up or down), IGNS will adjust 

the Scientific Alert Level by issuing a ‘Science Alert 

Bulletin’ 

In the case of a volcano in the ‘re-awakening’ category, 

a move from Level ‘0’ to Level ‘1’ does not necessarily 

signal imminent volcanic activity. Historically, seismic 

and deformation episodes have occurred at Taupo, 

Auckland, Rotorua, Okataina, and Raoul Island, which 

would have resulted in an adjustment to a level ‘1’ alert 

with no accompanying eruption threat. Similar episodes 

leading to Level ‘1’ alerts for volcanoes in the ‘reawakening’ category may be expected every 5 - 10 

years. 

Importantly, for the civil aviation community a change 

in the Scientific Alert Level triggers the immediate 

generation, or change of, a NOTAM on a Volcanic 

Hazard Zone (VHZ). 

5. SYSTEM PARTICIPATION ROLES 

Set out in Schematic 1 is a diagram showing the lines of 

communication and responsibility of participants in the 

NZVAAS. 

5.2 Civil Aviation Authority of New Zealand 

The CAA is responsible for ensuring a satisfactory 

means exists whereby civil aviation aircraft operations 

can be safely carried out near volcanic ash. The CAA is 

not responsible for providing any service to airlines to 

directly assist them with such operations. The CAA’s 

role is to: 

(a) Review the effectiveness of the volcanic 

ash information system from time to time. 

(b) Ensure ACNZ, MetService and IGNS have 

any delegations or permissions required 

under the Civil Aviation Act 1990 to carry 

out their roles. 

(c) Publish, in the appropriate medium, a clear 

statement of how the volcanic ash 

information system works in New Zealand. 

(d) Continue to publish any appropriate 

educational or technical information on 

aircraft operation in or near volcanic ash, 

the volcanic situation in New Zealand or 

any other relevant material. 

(e) Establish any new Volcanic Hazard Zone 

(VHZ) that may be needed to cover 

volcanoes other than those currently 

contemplated. 

5.3 Meteorological Service of New Zealand 

MetService’s responsibility is to provide civil aviation 

with enhanced and timely volcanic ash SIGMETs and 

any other volcanic activity or ash information packages 

required pursuant to New Zealand’s ICAO obligations, 

and to maintain volcanic NOTAMs. MetService’s role 

is to: 

(a) Maintain a watch over actual and possible 

volcanic events through the use of satellite 

and land based meteorological information 

systems and the use of atmospheric 

trajectory and dispersion models. 
Session 5 – Page 17 

(b) Notify IGNS of any possible eruption 

detected in New Zealand not already 

notified by IGNS. 

(c) Use suitable atmospheric trajectory and 

dispersion models to identify the probable 

path of ejected ash. 

(d) Use all appropriate internal and external 

procedures to generate timely SIGMETs to 

notify civil aviation of the present and 

likely future position of volcanic ash in 

New Zealand’s area of responsibility. 

(e) Maintain a Volcanic SIGMET watch and 

update the SIGMET bulletin as frequently 

as possible and within the ICAO guidelines. 

(f) Provide any extra information such as 

satellite imagery, ash trajectory information 

or other graphics that may be requested by 

civil aircraft operators. 

(g) Provide information to IGNS such as wind 

profile data or independent observation 

information that may be appropriate. 

(h) When notified by IGNS of a change in the 

official activity level (Scientific Alert 

Levels) immediately request ACNZ to issue 

the appropriate NOTAM. 

(i) Maintain the currency of any related 

NOTAM in liaison with ACNZ. 

(j) Maintain a watch on technological 

developments and apply any advances in 

this area to operations. 

5.4 Airways Corporation of New Zealand 

The responsibility of ACNZ is to provide to civil 

aviation the NOTAM service, access to volcanic 

SIGMET and appropriate VAR information pursuant to 

New Zealand’s ICAO obligations. It also collects, from 

aircraft, VAR information and disseminates this 

information to MetService, IGNS and accessible 

aircraft operators. The ACNZ role is to: 

(a) Ensure that meteorological reports 

(METARs, SPECIs) passed to MetService 

and civil aviation contains appropriate 

information on the presence (or not as the 

case may be during a volcanic episode) of 

volcanic ash or other volcanic phenomena. 

(b) Ensure that all AIREPs containing 

information on volcanic ash and Volcanic 

Activity Reports (VARs) received from 

aircraft are passed with utmost urgency to 

MetService and any other addressees on the 

VAR distribution list. 

(c) Ensure that updated Volcanic SIGMETs 

provided by MetService are expeditiously 

passed to aircraft in flight, especially those 

operating in the vicinity of any ash. 

(d) Upon the receipt of a notification from 

MetService that the Scientific Alert Level 

of a given volcano has been changed, 

immediately issue the appropriate 

NOTAM. (Table 2 defines the vertical and 

horizontal limits of the VHZ for given 

scientific alert levels) 

(e) Notify MetService 24 hours before the 

expiry of any given NOTAM and request 

an update or confirmation of cancellation. 

(f) Set up a system to notify operators which 

routes and procedures will be affected by 

each level of volcanic activity. 

(g) Ensure that VFR or IFR aircraft that require 

an ATC clearance to operate within the 

areas of concern will not be granted a 

clearance without a specific route request 

from the pilot. 

5.5 Institute of Geological and Nuclear Sciences 

The prime responsibility of IGNS is to keep MetService 

informed as to any volcanic activity taking place in New 

Zealand. The role of IGNS is: 

(a) Maintain monitoring of volcanoes in New 

Zealand territory, particularly Ruapehu, 

Ngauruhoe and White Island, on a 24-hour 

basis. This should encompass the ability to 

confirm or deny any reported or suspected 

ash eruption. 

(b) Notify MetService of any change in 

assessed official activity level (ie; Scientific 

Alert Levels) immediately that decision has 

been made. 

(c) Notify MetService should the risk 

assessment of any volcano change 

positively or negatively (ie; Scientific Alert 

Bulletin). 

(d) Advise MetService of any new eruption 

information as it becomes available. This 

includes information on; eruption time and 

expected activity period, eruption type 
Session 5 – Page 18 

(steam, gas, and ash) and any other relevant 

advice. 

5.6 Aircraft Operators 

The responsibility of aircraft operators is to ensure their 

aircraft do not operate in volcanic ash and to provide 

Volcanic Activity Reports (VARs) when appropriate. 

Their role is to: 

(a) Ensure procedures are incorporated in 

operations manuals for the reporting of 

volcanic events and ash, including the 

generation and distribution of these reports 

(VARs) following the prescribed 

international guidelines (ICAO). 

(b) Ensure that aircrew are fully aware of their 

civil aviation regulatory obligations insofar 

as Volcanic Hazard Zones (NOTAM) are 

concerned. 

(c) Ensure that aircrew have adequate 

background knowledge of the atmospheric 

and airframe effects of volcanic events 

especially in the context of the New 

Zealand volcanic situation. 

(d) Ensure procedures are incorporated in 

operations manuals for the safe operation 

of aircraft near areas of volcanic ash. 

(e) Ensure ACNZ is aware of their particular 

ash episode re-route preferences. 

6. EXPERIENCE 

Since the implementation of the NZVAAS in 1999, 

mainland New Zealand has not experienced any 

significant eruption events, although the NZVAAS 

system has been operating on a number of occasions. 

To ensure the system will operate well when the 

inevitable more significant volcanic event does occur, 

MetService conducts annual exercises, internally 

producing simulated agency outputs, interaction and 

responses. These exercises have been very helpful in 

both maintaining the currency of staff involved and in 

streamlining and improving processes. 

Experience with the issue of volcanic ash information in 

New Zealand has highlighted the difficulty on occasion 

of providing detailed information about volcanic ash in 

both textual and graphical formats. This can be a 

significant issue when eruptions from a particular 

volcano are continuous or quasi-continuous over a 

period of time, and when wind direction varies with 

height causing ash to move in different directions with 

height. Depicting this information graphically has 

proven to be difficult, and describing the information in 

textual messages has often resulted in lengthy and very 

complex messages. 

Over the time the NZVAAS has been operating, there 

has been increased interest in Government regarding 

overall geophysical risk mitigation. This has proved 

fortunate for the NZVAAS as it has resulted in better 

monitoring of New Zealand’s mainland volcanoes, and 

to a lesser extent, the offshore volcanoes. 

Foreign airline operators taking up operations to or 

within New Zealand have had difficulty in 

understanding the context of the NZVAAS in relation to 

State IAVW responsibilities. There have also been 

charging issues arising out of the separate contracting 

for the NZVAAS as opposed to the standard service 

contract for ICAO Annex 3 prescribed meteorological 

services to individual airlines. In every case these issues 

have been resolved through careful explanation of the 

two systems. Nevertheless, it would be advantageous to 

move toward a structure that identifies the NZVAAS as 

a State based operational part of the overall IAVW. 

In the absence of volcanic activity there is a natural 

tendency for airline operators to place less emphasis on 

volcanic ash risk mitigation procedures and systems. 

This seems to be inversely related to the size of the 

airline operation – the bigger operations have risk 

management personnel ensuring that their companies do 

maintain systems and carry out recurrency training. This 

is not always so with smaller operations. To increase the 

profile of volcanic activity risk, the CAA, MetService 

and ACNZ continue to highlight the NZVAAS and its 

advantages to the New Zealand aviation community. 

7. CONCLUSION 

The NZVAAS has proven to be a very effective system 

for New Zealand and this can be attributed largely to 

the formal arrangements between the participating 

organisations. It has also highlighted the importance of 

having co-operative and collaborative relationships 

between the regulator, the meteorological service 

provider, the air traffic service provider, the aircraft 

operators and the local volcanological organisation. 
Session 5 – Page 19 

Schematic 1, New Zealand Volcanic Ash Advisory System

Table 1, New Zealand Volcanic Scientific Alert Level System

FREQUENTLY ACTIVE VOLCANOES SCIENTIFIC REAWAKENING VOLCANOES 

White Island, Tongariro -Ngauruhoe, Ruapehu ALERT LEVEL Kermadecs, Northland, Auckland, Mayor Island, Rotorua, 

Okataina, Taupo, Egmont 

Volcano Status Indicative Phenomena Indicative Phenomena Volcano Status 

Usual dormant or 

quiescent state. 

Typical background surface activity; 

seismicity, deformation and heat flow 

at low levels. 0 

Typical background surface activity; 

seismicity, deformation and heat 

flow at low levels. 

Usual dormant or 

quiescent state. 

Signs of volcano 

unrest. 

Departure from typical background 

surface activity. 1 

Apparent seismic, geodetic, thermal 

or other unrest indicators 

Initial signs of possible 

volcano unrest. No 

eruption threat. 

Minor eruptive 

activity. 

Onset of eruptive activity, 

accompanied by changes to monitored 

indicators. 2 

Increase in number or intensity of 

unrest indicators (seismicity, 

deformation, heat flow etc.). 

Confirmation of volcano 

unrest. Eruption threat. 

Significant local 

eruption in progress. 

Increased vigour of ongoing activity 

and monitored indicators. 3 

Minor eruptions. High increasing 

trends of unrest indicators, 

significant effects on volcano and 

possibly beyond. 

Minor eruptions 

commenced. Real 

possibility of hazardous 

eruptions. 

Hazardous local 

eruption in progress. 

Significant change to ongoing activity 

and monitoring indicators. Effects 

beyond volcano. 4 

Eruption of new magma. Sustained 

high levels of unrest indicators, 

significant effects beyond volcano. 

Hazardous local 

eruption in progress. 

Large scale eruption 

now possible. 

Large hazardous 

eruption in progress. 

Destruction with major damage 

beyond volcano. Significant risk over 

wider areas. 5 

Destruction with major damage 

beyond active volcano. Significant 

risk over wider areas. 

Large hazardous 

volcanic eruption in 

progress. 

Table 2, Automatic Volcanic Hazard Zone Limits for NOTAM

Volcano Alert Volcanic Hazard Zone Upper Limit 

Level 

Radius from 

Vent (nm) Ruapehu 

(VHZ 314) 

Ngauruhoe 

(VHZ313) 

White Island 

(VHZ 211) Any other NZ volcano 

1 3 12,200ft AMSL 10,500ft AMSL 4,500ft AMSL 3000 ft above vent 

2 8 FL 150 FL 150 FL 150 FL 150 

3 16 FL 330 FL 330 FL 330 FL 330 

4 27 FL 480 FL 480 FL 480 FL 480 

5 >50 unlimited unlimited unlimited Unlimited 

ACNZ MetService IGNS

Aircraft Operators

Volcano

VAR feedback

SIGMET (RTF etc)

VAR

by

RTF

VAR by fax 

(post flight)

SIGMET (AFTN)

VARs 

Alert level 

& eruption 

information

Satellite or

other eruption 

Information

Electronic &

visual

eruption

 & status

information

Confirn or

deny

Independent information

observations

or liaison

Other 

people

NOTAM Request

(& confirmation)

NOTAM

Normal 

preflight Met.

information

VAR feedback
5.5 

Session 5 – Page 21 

PREVENTION OF VOLCANIC ASH ENCOUNTERS IN THE 

PROXIMITY AREA BETWEEN ACTIVE VOLCANOES AND 

H E AV Y A IR TR A F F IC R O U TES 

Saburo Onodera,Flight Crew Training Department, 

Japan Airlines, Tokyo, Japan 

1. Introduction 

 At the First International Symposium 

on Volcanic Ash and Aviation Safety in 1991, 

countermeasures against volcanic ash 

encounters were discussed and proposed by 

various scientific, aviation and government 

leaders. One of the most significant results 

that came out of this symposium was the 

establishment of the ICAO VAAC 

(International Civil Aviation Organization 

Volcanic Ash Advisory Center). However, 

recent reports indicate that the volcanic ash 

encounter from the Miyakejima volcano 

eruptions in 2000 could not have been 

prevented under the current ICAO system. 

This paper discusses issues on prevention of 

volcanic ash encounter in the proximity area 

between active volcanoes and heavy air traffic 

routes, by reviewing, as a case study, the 

Miyakejima volcano eruption case in Japan on 

Aug.18th, 2000, along with the incident from 

the Izu-Oshima volcano eruption in 1986. 

2. Volcanic ash encountering incidents at 

the Miyakejima Volcano eruption on Aug. 

18th, 2000 

 Miyakejima volcano is located 

approximately 110 nautical miles southwest 

of Narita airport in Japan. The explosive 

eruptions at Miyakejima volcano on Aug.18th, 

2000 caused volcanic ash encounter by large 

transport aircraft in the vicinity of the volcano.

Fig1 shows the location of Miyakejima 

volcano and the estimated points of volcanic 

ash encounters by two aircraft. In this region, 

there are many airways which have heavy air 

traffic volume in the proximity of the active 

volcano. The question that arises from this 

Miyakejima incident in 2000 is why couldn’t the 

volcanic ash encounters be prevented under the 

current ICAO regime, which was supported by 

various types of new technologies. In order to 

prevent further encounter incidents in this region 

it will be necessary to review the facts at the 

time of the volcanic ash encounter. The actions 

by the pilot and ATC (Air Traffic Control) 

controller are to be reviewed as well as 

information available at the time of encounter.
Session 5 – Page 22 

2.1. Actions Taken By the Pilot

 

 On Aug.18th, 2000, shortly after the 

explosive eruption had begun, volcanic ash 

encounters were reported by two Narita 

inbound flights, one was a B747 from Saipan, 

and the other was a B737 from Guam. Serious 

damage was found on both aircraft during a 

maintenance check at Narita. Both aircraft 

encountered volcanic ash while flying at 

FL340 and FL360 respectively on an air route 

to Narita near the Miyakejima volcano. The 

air space south of Narita is complicated by the 

structure of heavily flown air routes that are 

located in close proximity to an active volcano. 

In this air space, options for pilots and ATC 

controllers to alter a planned route during flight 

are very limited due to the threat of a possible 

mid air collision. In this area, arriving/departing 

routes to/from Narita and Haneda are closely 

located and/or crossing each other. In this region, 

it is especially important for pilots to fly strictly 

by following ATC instructions. Pilots, therefore, 

rely very heavily on the ATC controllers’s 

decision making. The two aircraft which 

suffered a volcanic ash encounter were 

following ATC instructions at the time of the 

encounter, believing that ATC were radar 

vectoring them safely away from any volcanic 

ash encounter. But eventually the two aircraft 

inadvertently encountered volcanic ash. The 

pilot’s ensuing actions were in accordance with 

the recommended procedures in the event of a 

volcanic ash encounter, which prevented an 

inflight engine shut down and led them to a 

safe landing at Narita. Even though an inflight 

engine flame out was prevented by the pilots’ 

appropriate actions, the engines were seriously 

damaged, as well as other airplane components 

by the volcanic ash encounter. Questions still 

remain as to why both aircraft volcanic ash 

encounters could not be prevented while the 

pilots were flying in accordance to ATC 

instructions. 

2.2. Actions by ATC Controller 

 After Miyakejima volcano erupted, on 

Aug.18th, 2000, ATC controllers directed all 

Narita inbound flights from south to the 

furthest easterly route, believing that it was 

the safest course of action. However, the 

routes gradually became invaded with 

volcanic ash, and ATC could no longer 

provide effective radar vectoring (Table1). 

The information available at that time, which 

affected decision making in ATC, were 

SIGMET (Significant Meteorological 

information) and PIREP (Pilot Report). The 

volcanic ash transport and dispersion forecast 

were also provided to ATC. The ATC 

controllers were supposed to coordinate traffic 

flow and provide safe avoidance vectoring to 

concerned aircraft based on relevant 

information such as the volcanic ash forecast 

and/or SIGMETs, PIREPs and etc,. 

Aircraft Airport of Estimated Narita Flight

Type Origin ATO(z) Arrival(z) Condition

B747 SPN 0824 0859 Normal

B747 SYD 0831 0906 Normal

B747 GUM 0849 0924 Normal

B747 CNS 0905 0940 Normal

DC10 GUM 0916 0951 Normal

B747 SPN 0930 1003 Encounter

B737 GUM 0932 1005 Encounter

Table 1. Flight conditions of the encountered aircraft

and the preceding aircraft on the same route

Note: Estimated ATO incident point are based on available

data and calculation by the author
Session 5 – Page 23 

2.3. Information on the location and 

movement of volcanic ash, by the volcanic 

ash transport and dispersion forecast 

SIGMET, and PIREP

 A various type of information had been 

issued at explosive eruptions at Miyakejima 

volcano on Aug.18th, 2000. The information 

was disseminated to relevant organizations 

according to the pre-determined destination 

table. Critical information, which would have 

affected the decision making on volcanic ash 

avoidance route by ATC, was thought to be 

included within the distributed information 

such as SIGMETs, VAAs (Volcanic Ash 

Advisory), and PIREPs. 

2.3.1. Volcanic ash transport and dispersion 

forecast 

 Since the eruptions began at 

Miyakejima volcano in June, 2000, the volcanic 

ash transport and dispersion forecast was 

published and distributed to relevant 

organizations. On Aug.18th, 2000, at the time 

of the explosive eruptions of Miyakejima 

volcano, the volcanic ash transport and 

dispersion forecast was issued. However, the 

forecasted direction of the volcanic ash 

movement was southward from the crater, 

while the observed wind direction was 

southeastward. This slight disagreement of 

movement direction, between the forecast and 

the observed one, may have affected, to some 

extent, the decision making process by ATC 

on which route to select as the volcanic ash 

avoidance route for approaching aircraft to the 

area. It was also revealed that the volcanic ash 

transport and dispersion forecast included, 

more or less, a forecast error, which could 

have adversely affected the decision by ATC 

on selecting the correct volcanic ash 

avoidance route. This case shows us that in an 

area where the air route is densely located, we 

cannot depend too much on the forecast in the 

contaminated area. 

2.3.2. SIGMET, VAA 

 An extract of SIGMETs and VAAs is 

shown in Table2. The record of SIGMET and 

VAA indicates that the explosive eruption at 

0802z on Aug.18th, 2000, was notified by 

VAA issued at 0815z, which mentioned that 

the plume height was above FL190. Then 

SIGMET No1 was issued at 0825z, stating 

that volcanic ash top FL190 and intensifying. 

VAA No2 at 0835z reported that the ash top 

above FL400 extending southeast. SIGMET 

No2 at 0840z stated, quoting PIREP at 0829z, 

that the volcanic ash top above FL400 drifting 

to E-SE and intensifying. VAA No3 at 0925z 

delineated area of volcanic ash as of 0832z 

and added the forecast area of volcanic ash 

contamination through the next day. Based on 

the record of SIGMETs and VAAs, the 

VAA No1 0815 Erupted at 0802z, ash climbing to above FL190......

SIGMET No1 0825 Obs at 0802z VA top FL190 Movement unknown, intensifying...

VAA No2 0835 VA above FL400, extended SE, by PIREP at 0829z.......

SIGMET No2 0840 VA above FL400, moving E-SE, intensifying ,by B747 at 0829z....

SIGMET No3 0855 VA above FL400 moving E-SE, intensifying at 0829z by B747...

VAA No3 0925 VA obs by Satellite at 0832z 34.1N 139.4E,.... Outlook at 12z.......

B747 0930 Encounter VA at FL340 at approx 50 nm SE of volcano.

B737 0932 Encounter VA at FL360 at approx 50 nm SE of volcano.

Type of

Information

Time of

Issue (z) Outline of Content

Table 2. Extract from SIGMET and VAA on the Miyakejima explosive eruption

initiated at 0802UTC on Aug.18th, 2000
Session 5 – Page 24 

issuance of the initial warning, VAA, was 13 

minutes after the initiation of the explosive 

eruption. The timing of issuance of SIGMETs 

and VAAs were rather swift and quick under 

the circumstances. Although the SIGMET 

mentioned the height of the volcanic ash and 

the movement direction of volcanic ash from 

an early stage, the moving speed and the 

contaminated area of volcanic ash were not 

included until a later SIGMET. The lack of the 

critical information was another factor 

unfavourable to volcanic ash avoidance. 

3. Comparison to the Izu-Oshima case in 

1986 

3.1. Izu-Oshima volcano eruption on Nov. 

21st, 1986. 

 Izu-Oshima volcano is located 

approximately 80nm southwest of Narita 

airport and 38nm north northwest of 

Miyakejima volcano. On Nov. 21st, 1986, 

Izu-Oshima volcano erupted explosively 

and a volcanic ash cloud top soon reached a 

height of more than 10km above the crater. 

After this eruption, a volcanic ash encounter 

took place as shown in Table3. In this 

eruption, the volcanic ash encounter was 

approximately 40 to 60 nm east of the volcano, 

while at the Miyakejima volcano eruption in 

2000, the encounter took place approximately 

50 nm southeast of volcano. The relative 

distance between the crater and the 

encountering point in Miyakejima case is 

similar to that in the Izu-Oshima case. 

3.2. Countermeasures against volcanic ash 

encounter 

 Table4 shows the countermeasures 

against volcanic ash encounters in 1986 and in 

2000. It is clear that in 2000, we had much 

more data available than what we had in 1986. 

It can be said that, in 2000 we had better 

quantity and quality of data at hand than in 

1986. In spite of much better conditions, the 

fact is that the volcanic ash incidents could not 

be prevented. 

3.3. Lead Time before encounter 

 Table5 shows the time sequence after 

the start of the explosive eruption until the 

actual volcanic ash encounter. The lead time 

Eruption Detection Available Available

SIGMET Available Available

NOTAM Available Available

Satellite Imagery Available Available

Split Window N/A Available

VAAC. VAA N/A Available

Dispersion Forecast N/A Available

Table 4. Improvement of countermeasures

 Year/Volcano

Countermeasures

1986

Izu-Oshima

2000

Miyakejima

Aircraft Type B747 DC8 DC10 B747

Time of Encounter (Z) approx. 0900 approx. 0900 approx. 0920 Unknown

Portion NRT-HKG TPE-NRT NRT-BKK BOM-NRT

Location 60nm S of NRT 40nm E of Vol. 60nm E of Vol. Unknown

Flight Phase Climb Descent Climb Descent

Altitude (feet) 20,000-30,000 30,000-26,000 20,000-23,000 17,000-10,000

Condition (Visibility) Night(good) Night(good) Nighr(good) Unknown

 (1) Erosion was found on windsheild , horizontal and verical stabilizer.

Spark. Smell of

burning wood Observed Phenomena Unusual odour Light to Mod

turbulence

Static discharge

on windshield

Erosion (1). VA

in pitot tube

Fine scratches

on windshield

Small particle

like fog

 Table 3. VA Encounter at Izu-Oshima volcano eruption on Nov.21st 1986

Aircraft Damage None
Session 5 – Page 25 

of the explosive eruptions before the encounter 

is approximately 1 hour 40 minutes in the 

Izu-Oshima case and 1 hour 28 minutes in the 

Miyakejima case. This fact shows that we had 

plenty of lead time before the actual encounter. 

We may have had more desirable results if we 

could have better utilized the lead time by 

continually updating and assessing the situation. 

4. Lessons learned from the incidents and 

the proposals for the area 

 These volcanic ash encounter cases are 

similar in the region of proximity of active 

volcano and heavy air traffic route. The 

Izu-Oshima volcano case in 1986 and 

Miyakejima volcano case in 2000 seems to 

indicate the following facts. 

 a. Volcanic ash encounters took place even 

after 14 years of progress in the international 

volcanic ash prevention program and the 

volcanic ash detection and movement prediction 

technique. 

 b. Even though pilot reports were submitted 

from an early stage after the eruption and 

SIGMETs were also issued consecutively, the 

volcanic ash avoidance route provided to Narita 

inbound flights from the southern airspace were 

not changed until after the encounter had taken 

place. This infers the difficulties of dealing with 

the information derived from SIGMET and 

PIREP, and the difficulty of applying them into 

the ATC decision making process for volcanic 

ash avoidance 

 c. In the area where the air route structure is 

complex with a heavy load of air traffic in the 

proximity area to an active volcano, positive 

ATC decision making is crucially important for 

preventing volcanic ash encounters. 

 d. In those areas like c. above, basic education 

on the knowledge of volcanic ash encounter 

incident and practical education on the 

knowledge of volcanic ash avoidance is critical. 

Annual drills for ATC are essential 

in the area where heavy air traffic 

route are located in the proximity to 

active volcanoes. 

Acknowledgement 

 I would like to thank those persons who 

provided me data pertinent to volcanic ash 

encounter incident in this region. At the same 

time I would like to thank those people who 

contribute to the prevention of volcanic ash 

encounter. I would like to specially thank the 

ex-director of SVO (Sakurajima Volcano 

Observatory, Kyoto University) and professor 

emeritus of Kyoto University, Dr.Kosuke Kamo, 

and the director of SVO, Dr.Kazuhiro Ishihara 

and SVO staff, and Dr. Hiroshi Tanaka, Tsukuba 

University, and Mr.Michael Kelly, Japan 

Airlines, for their continuous advise and help to 

the author since 1980s. 

Reference 

 

Brantley, S. R., (Editor), 1990, The eruption of 

Redoubt Volcano, Alaska, December 14, 1989 

- August 31, 1990, U.S. Geological Survey 

Circular 1061, p 7-24. 

Nov.21 1986 Aug.18 2000 Dec.15 1989

Time Izu-Oshima Miyakejima Redoubt

Eruption time 0720z 0802z 1915z

Encounter time 0900z 0930z 2045z

 Table 5. Lead time before volcanic ash encounter

Lead time before

encounter

1hour 40 min 1 hour 28 min 1 hour 30 min
5.6 

Session 5 – Page 27 

A PROGRAM FOR RESEARCH AND SYSTEMS INTEGRATION TO HELP 

MITIGATE THE VOLCANIC ASH HAZARD TO AVIATION 

Tenny A. Lindholm, The National Center for Atmospheric Research (NCAR) 

Boulder, Colorado, USA 

Introduction 

 The National Center for Atmospheric 

Research (NCAR) Research Applications 

Program (RAP) is currently addressing five 

aviation weather hazard areas through 

emerging weather products: convection and 

convective hazards; in-flight icing; turbulence 

(terrain-induced, convective-induced, jet 

stream, and shear); remote and oceanic 

weather hazard diagnosis and forecasts; 

ceiling and visibility. The National Weather 

Service (NWS) and Federal Aviation 

Administration (FAA) are transitioning these 

products to operations for use by pilots, 

dispatchers, flight service specialists, and air 

traffic controllers and managers. Underlying 

research, verification, dissemination methods, 

and user interface/display development have 

been sponsored primarily by the FAA Aviation 

Weather Research Program (AWRP), with 

joint sponsorship from the NASA Aviation 

Safety Program (AvSP). 

 The Oceanic Weather Product 

Development Team (OWPDT), one of eleven 

PDTs sponsored by the AWRP, is developing 

and introducing remote and oceanic weather 

products. The OWPDT, as one of its taskings 

in response to formal FAA requirements, is 

developing advanced techniques that will 

detect, forecast, and disseminate information 

on volcanic ash plume hazards to aviation 

operators and users. Airborne volcanic ash 

constitutes a recognized threat to aviation that 

can severely damage jet aircraft engines 

through erosion, corrosion and congestion. A 

number of well-documented near-fatal 

accidents have occurred, and even relatively 

minor encounters have resulted in extensive 

aircraft damage. Volcanic ash contamination 

may render large volumes of airspace 

unavailable, necessitating costly rerouting 

contingencies, and problematic ash-related 

aircraft encounters have been reported days 

after an eruption and thousands of miles from 

the source. 

Current Volcanic Ash Products Available to 

Users 

Current volcanic ash products 

available to aviation users include (as 

extracted from the FAA User Needs Analysis 

[UNA] document, dated 5 September 2001): 

Volcanic Ash Significant Meteorological 

Information (SIGMET): The product generally 

describes the horizontal and vertical extent 

and the expected trajectory of the volcanic ash 

cloud. 

Aviation Routine Weather Report/Special 

Aviation Weather Report (METAR/SPECI): An 

aviation weather observation for a specific 

airport. 

Notice to Airmen (NOTAM)/Volcanic Ash 

NOTAM (ASHTAM): A NOTAM is a statement 

concerning the establishment, condition or 

change (e.g., hazard) in any component of the 

NAS. The ASHTAM serves as a status report 

for volcanoes that are active, but not 

necessarily erupting. 

Pilot Report (PIREP): A report of 

meteorological phenomena encountered or 

observed by the flight crew while the aircraft is 

in flight. 

Aerodrome Forecast (TAF): A forecast 

prepared for specific airports of important 

aviation parameters such as ceiling and 

visibility, winds and weather/obstructions to 

vision. 

Volcanic Ash Forecast Transport and 

Dispersion Model (VAFTAD): A graphic 

depiction of the Volcanic Ash Advisory and a 

projection of the expected transport of the ash 

cloud over a specified period of time in space 

and flight level. 

Volcanic Ash Advisory Statement (VAA): A 

report distributed in text form to air traffic 

service units and meteorological watch offices 

concerning the presence of a volcanic ash 

cloud. 
Session 5 – Page 28 

User Needs as Documented in the FAA’s 

User Needs Analysis 

Capability shortfalls and goals are 

stated quantitatively in the UNA for each 

attribute. Qualitative descriptions of stated 

needs can be summarized as follows: 

• In general, integration of the various 

agencies responsible for generating 

information on volcanic eruptions and ash 

clouds, to include a collaborative 

approach that (a) informs all stakeholders 

on the most current information and (b) 

permits all stakeholders to participate in 

updating information. There is no common 

database of text and graphic products that 

all users can access, which adversely 

affects the collaborative decision-making 

process. Stakeholders include airlines 

(dispatch, flight operations, meteorology), 

air traffic management and control, NWS, 

USGS. 

• Improved detection of volcanic eruptions 

globally, to include forecasts of 

volcanic activity and characterization 

of the initial ash cloud. 

• Better characterization of the ash cloud as 

the event progresses: 

o Detection accuracy, location, 

horizontal extent 

o Vertical extent of hazard 

o Ash density and chemistry 

o Differentiate volcanic ash hazard 

from meteorological cloud 

• More frequent product updates. 

• Improved timeliness of updates (from 

observation or product generation to user 

access). 

• Better forecasts: 

o Location, horizontal extent 

o Vertical extent of hazard 

o Ash density and chemistry 

o Longer valid time 

o Dissemination for flight planning 

• Better training for airline operation centers 

(AOCs), flight crews, and air traffic control 

specialists. 

• Ready access to all information for all 

users (AOCs, flight crews, and air traffic 

control specialists) including graphical 

updates to the airborne flight crew. 

• Regarding graphical products, they need 

to be higher resolution and referenced to 

planned flight profile. 

Specific scientific and engineering 

plans and tasks have been defined by the 

OWPDT in response to these formal user 

needs. We emphasize that considerable 

research on defining volcanic ash hazards and 

detection of dangerous eruptions is already 

underway. The OWPDT plans to assume an 

integration role as these new capabilities 

emerge, as well as defining new research 

areas as satellite detection capability 

improves. Although the OWPDT’s initial focus 

is on the Washington and Anchorage Volcanic 

Ash Advisory Centers (VAAC), coordination 

with the Darwin, Tokyo, and Montreal VAACs 

is also planned. The Team also includes 

NASA, the U.S. Geological Survey, the U.S. 

National Weather Service, and other centers 

of expertise in satellite sensing technologies 

and the characterization of volcanic ash 

hazards. 

Plans and Progress 

 In its role as integrator, the OWPDT 

hopes to bring together the research and 

development that targets the volcanic ash 

hazard to optimize the quality of information 

provided to users, recognizing that no one 

piece of data will complete the process. 

Therefore, our focus will be on the use of 

“expert system” or fuzzy engine integration of 

diverse data sources and diagnostics to 

address the detection and dispersion 

problems. The OWPDT is also teaming with 

the NWS and NOAA’s Forecast Systems 

Laboratory to develop a collaborative display 

concept and tool that will host emerging 

automated products and allow the 

stakeholders to view them and collaboratively 

alter them as required. These, of course, are 

long-range goals; however, they represent the 

best path to operations that will begin to 

address the formally documented user needs. 

We plan to introduce new capabilities to 

operations as they complete user evaluations 

and verification. Finally, through applied 

research, we intend to identify new satellite 

sensing capabilities that in the long term might 

be included in future geostationary satellites 

that can better detect and track volcanic ash 

plumes. 

 Some of the specific tasks the 

OWPDT has identified thus far include: 
Session 5 – Page 29 

• Integration and display of VA SIGMET 

graphics and advisories on the OW web site 

(http://www.rap.ucar.edu/projects/owpdt/), 

representing an early capability. This display is 

currently running in test mode, creating global 

graphics from textual SIGMETs with a 97% 

success rate. Figure 1 shows the current OW 

domains and an example display. 

• Ultimately, near-complete automation, with 

minimal mandatory human intervention. 

• Capability to issue short-term pre-eruption 

advisories during episodes of potential 

volcanic unrest. Inclusion of geophysical data 

and input from the geosciences community. 

• Improved detection of remote, 

unmonitored volcanic eruptions, possibly using 

a combination of teleseismic and satellite data. 

• Incorporation of recently developed 

satellite interpretation technologies (e.g., 

multispectral analysis and channel splitting) to 

enhance ash cloud tracking. The OWPDT 

collaborates with several satellite centers of 

excellence with the goals of using current 

sensing technologies better, and identifying 

promising future technologies as well. For 

example (there are others), 

• The Moderate Resolution Imaging 

Spectroradiometer (MODIS) data has 

demonstrated considerable potential for 

mapping several characteristic 

constituents of the ash cloud, including the 

ash particles, on the basis of distinct 

radiative properties in the thermal infrared. 

• The Advanced Spaceborne Thermal 

Emission and Reflection Radiometer 

(ASTER) instrumentation is ideal for 

detecting the thermal anomalies 

associated with volcanic eruptions. It has 

even been suggested that ASTER data 

may be used to identify regions of volcanic 

unrest, potentially allowing the forecast of 

an increased eruption risk. Although 

ASTER data has limitations that are 

inherently associated with the “on 

demand” nature of the instrument, the 

high spatial resolution of the data set may 

be extremely useful when available. 

• The Multi-angle Imaging 

Spectroradiometer (MISR), which heavily 

emphasizes aerosol measurements, may 

provide additional capability to detect and 

monitor ash clouds of sufficient age that 

they are no longer thermally anomalous. 

 • The Advanced Microwave Scanning 

Radiometer for EOS (AMSR-E) may 

prove useful for detection of young 

ash plumes when millimeter-sized 

particles may still be entrained. Data 

from this sensor may alleviate 

problems mentioned above in the 

detection of young ash plumes. 

 • Improvements to plume and ash cloud 

dispersion modeling, including highresolution wind-field modeling and 

realistic particle size distributions. A 

fuzzy integration of several dispersion 

modeling systems, taking advantage of 

the strengths of each, could improve 

dispersion forecasts. 

 • Development of a global, highresolution, satellite-derived wind field 

that can be integrated with the 

dispersion model system. 

 • Incorporation of “intelligent systems” 

capability, allowing the integration of a 

wide variety of input sources. 

 • Output will be graphical and generated 

in response to a user request, 

accessible even to airborne flight crews. 

 • Ash cloud characterizations will consist 

of detailed density contours, as opposed 

to the simple “visible cloud outlines” that 

are currently distributed. 

 • Task-oriented training for both 

meteorological and aviation user 

communities. 

Conclusion 

 The OWPDT has an ambitious plan to 

help improve the current volcanic ash 

information provided to aviation end-users, 

and is continuing work to establish 

collaborations with agencies and institutions 

that have needed expertise. Of particular 

interest is the realization that current sensing 

technologies might not have the capabilities to 

satisfy needs completely, and NASA’s remote 

sensing work supporting the design of future 

satellite sensing suites will definitely be a 

crucial element of the OWPDT’s efforts. 

Meanwhile, as incremental capabilities 

emerge and are verified, they will be 

introduced to the operational community to 

help mitigate both the safety and efficiency 

impacts the volcanic ash hazard has on 

aviation. 
Session 5 – Page 30 

This research is in response to 

requirements and funding by the Federal 

Aviation Administration (FAA). The views 

expressed are those of the author and do not 

necessarily represent the official policy or 

position of the FAA. 

Turbulence

Thunderstorm

Tropical storm

Volcanic ash

Icing

Dust/Sand storm

Figure 1 
5.7 

Session 5 – Page 31 

EXPLOSIVE VOLCANIC ERUPTIONS ACROSS THE HEAVILY TRAVELED NORTH 

PACIFIC AIR ROUTES: FREQUENCY, DURATION, AND IMPACT ON AVIATION 

Thomas P. Miller, U.S. Geological Survey, Alaska Volcano Observatory, Anchorage, AK, USA 

[tmiller@usgs.gov] 

The 100 historically active volcanoes (about 1/6 of the world’s active volcanoes) that rim the North 

Pacific along the Alaska Peninsula, Aleutian Islands, Kamchatka Peninsula, and the Kurile Islands are 

part of the highly explosive “Pacific Rim of Fire”. Analysis of the past 200-year record indicates that 

these volcanoes collectively average 3-5 eruptions/year. Most of these eruptions are relatively short-lived 

events lasting only a few days producing limited ash emission to low altitudes; however, a significant 

minority of eruptions last for months or even a few years. The 1989-90 eruption of Redoubt volcano near 

Anchorage, for example, lasted 4 months and had at least 20 explosive events that resulted in ejection of 

volcanic ash to >30,000 feet. Prevailing winds commonly carry volcanic ash across the North Pacific 

(NOPAC) and Russian Far East air route tracks that carry as many as 240 cargo and passenger flights per 

day. About 5 days/year, volcanic ash from these eruptions is at cruise altitudes of > 30,000 feet ASL and 

perhaps on another 10-15 days, airborne volcanic ash is at sufficient altitude to be of potential concern to 

aircraft routing, payloads, and scheduling. The severity of the hazard is indicated by the past 20 year 

record that shows encounters between airborne volcanic ash and commercial aircraft in the North Pacific 

have caused an estimated $100 million dollars damage to aircraft, frequently disrupted air traffic, and 

occasionally required the closing of airports. This impact on aviation has led to the establishment of a 

color code to rapidly alert the aviation community to hazardous conditions, increased seismic and satellite 

monitoring, and detailed geologic studies to determine eruptive histories of active volcanoes throughout 

the region. 
P5.1 

Session 5 – Page 33 

FIRST 8 HOURS OF VOLCANIC ERUPTIONS: A NORTHWEST AIRLINES EXAMPLE & 

RECOMMENDATION OF REVISED FLOW OF ASH INFORMATION FOR AVIATION 

Tom Fahey, Manager, Meteorology, Northwest Airlines, 

Minneapolis/St. Paul, Minnesota, USA 

Currently, according to ICAO Annex 3, there are five steps in the process of notifying pilots and 

dispatchers of volcanic ash or volcanic eruptions. This process cuts across a spectrum of organizations 

and professionals. It requires close coordination to ensure that all airlines in the affected airspace receive 

the needed information for the safety of flight. Time is of the utmost importance in getting the message 

out. Even though ICAO describes the functional responsibilities for Meteorological Watch Offices, 

Volcanic Ash Advisory Centers, Volcano Observatories, and Area Control Centers, there is a need to reexamine the inter-relationships between these organizations and how information is gathered and 

exchanged. This paper will describe not only the existing protocol but provide a conceptual framework of 

how to streamline or improve the standardization of exchanging information and data based on prior 

Northwest Airlines experience and deficiencies in the system. 
INTERAGENCY 

WORKING GROUP FOR VOLCANIC ASH (WG/VA) 

MS. GRACE SWANSON, Chairperson* 

NOAA/NESDIS 

Department of Commerce 

MR. STEVEN ALBERSHEIM 

Federal Aviation Administration 

Department of Transportation 

MS. MARIANNE GUFFANTI 

U. S. Geological Survey 

Department of the Interior 

MR. JOHN HAYNES 

National Aeronautics and Space Administration 

MR. CHARLES HOLIDAY 

Air Force Weather Agency 

Department of Defense 

MR. RICHARD WUNDERMAN 

Smithsonian Institution 

MS. BARBARA STUNDER 

NOAA/ARL 

Department of Commerce 

MR. CHRISTOPHER STRAGER 

NOAA/NWS 

Department of Commerce 

MR. LEONARD SALINAS (Technical Advisor) 

United Air Lines 

MR. ED MILLER (Technical Advisor) 

Air Line Pilots Association 

Mr. Donald “Doc” Carver, Executive Secretary 

Office of the Federal Coordinator for 

Meteorological Services and Supporting Research 

* Working Group Chair rotates among NOAA, FAA, and USGS 

THE 2ND INTERNATIONAL CONFERENCE ON VOLCANIC ASH AND AVIATION SAFETY 

PLANNING COMMITTEE 

MS. MARY CAIRNS, Chairperson 

Office of the Federal Coordinator for 

Meteorological Services and Supporting Research 

MR. DONALD “DOC” CARVER 

Office of the Federal Coordinator for 

Meteorological Services and Supporting Research 

 

MR. STEVEN ALBERSHEIM 

Federal Aviation Administration 

MS. GRACE SWANSON 

NOAA/NESDIS 

MS. MARIANNE GUFFANTI 

U. S. Geological Survey 

MR. ED MILLER 

Air Line Pilots Association 

MR. THOMAS FRAIM 

Office of the Federal Coordinator for 

Meteorological Services and Supporting Research 

MS. ERIN McNAMARA 

Office of the Federal Coordinator for 

Meteorological Services and Supporting Research 

MR. KENNETH BARNETT 

Office of the Federal Coordinator for 

 Meteorological Services and Supporting Research