Summary Report 1990 

U.S. DEPARTMENT 

OF COMMERCE 

NATIONAL 

OCEANIC AND 

ATMOSPHERIC 

ADMINISTRATION 

ENVIRONMENTAL 

RESEARCH 

LABORATORIES 

• 

1 

• 

• 

• 

Climate Monitoring 

and Diagnostics Laboratory 

No. 19 

Summary Report 1990 

Eldon E. Ferguson, Editor 

Rita M. Rosson, Assistant Editor 

Boulder, Colorado 

December 1991 

U.S. DEPARTMENT OF COMMERCE 

Robert A. Mosbacher, Secretary 

National Oceanic and Atmospheric Administration 

John A. Knauss, Under Secretary for Oceans and Atmosphere/Administrator 

Environmental Research Laboratories 

Joseph 0. Fletcher, Director 
NOTICE 

Mention of a commercial company or product does not constitute an endorsement by 

NOAA Environmental Research Laboratories. Use for publicity or advertising 

purposes of information from this publication concerning proprietary products or the 

tests of such products is not authorized. 

For sale by the National Technical Information Service, 5285 Port Royal Road 

Springfield, VA 22161 

ii 
Contents 

CMDL Staff, 1990 .......................................................................................................................................... vi 

CMDL Station Information ............................................................................................................................. vii 

1. Introduction .. ... ..... .... ........ ................ .... ........ ........ ... . ........... ......... ............ .... .... ........ ........ ........ .... ....... 1 

2. Observatory Reports ............................................................................................................................ 2 

2.1 . Mauna Loa................................................................................................................................ 2 

2.1.1. Operations................................................................................................................... 2 

2.1.2. Programs ..................................................................................................................... 2 

2.2. Barrow ... .. .. .... ..... ....... .. .. ... . ................ .... .... ........ .... .... .... .... ................ ........ .... ........ .... .... ........... 7 

2.2.1. Operations .... .... .... ................ .... .... .... .... .... .... ........ ................ .... .... .... ........ .... .... .... ....... 7 

2.2.2. Programs ...... .... .... ................ .... .... ........ .... .... .... ................ .... .... .... .... .... .... ........ ........... 8 

2.3. Samoa ....................................................................................................................................... 12 

2.3.1. Operations ................................................................................................................... 12 

2.3.2. Programs ..................................................................................................................... 12 

2.4. South Pole ................................................................................................................................ 15 

2.4.1. Operations................................................................................................................... 15 

2.4.2. Programs ..................................................................................................................... 16 

2.5. References ................................................................................................................................ 19 

3. Atmospheric Radiation Monitoring Group ........................................................................................... 20 

3.1. Continuing Programs ................................................................................................................ 20 

3 .1.1. Surface Radiation .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. ... . .. .. .. .. . ... ... . . .. .. ... .... .... . ... . .. . . ... .. .. .. .. . . .. .. . . .. .. .. .. ... 20 

3.2. Special Projects......................................................................................................................... 22 

3.2.1. Spectral Response Characteristics of Robertson-Berger Meters ................................... 22 

3.3. References ................................................................................................................................ 23 

4. Carbon Cycle Group ............................................................................................................................ 24 

4.1. Continuing Programs ................................................................................................................ 24 

4.1.1. In-Situ Carbon Dioxide Measurements ........................................................................ 24 

4.1.2. Flask Sample Carbon Dioxide Measurements .............................................................. 24 

4. 1.3. In-Situ Methane Measurements ................................................................................... 27 

4.1.4. Flask Measurements of Methane ................................................................................. 27 

4.1.5. Flask Measurements of Carbon Monoxide.................................................................... 30 

4.2 Reference Gas Standards ........................................................................................................... 32 

4.2.1. Carbon Dioxide Standards............................................................................................ 32 

4.2.2. Methane Standards ..................... ... .... .... ........ .................... ........ .... .... .... .... ........ .... ....... 32 

4.3. Special Projects ........................................................................................................................ 33 

4.4. References ......... ................................................ .................................................................... ... 33 

5. Aerosols, Ozone, and Water Vapor Group ........................................................................................... 34 

5.1. Continuing Programs ................................................................................................................ 34 

5.1.1. Surface Aerosols.......................................................................................................... 34 

5. 1.2. Total Ozone Observations............................................................................................ 36 

5.1.3. Umkehr Observations................................................................................................... 37 

5.1.4. Calibration of NOAA-CMDL Dobson Spectrophotometers.......................................... 38 

5.1.S. International Calibration of Dobson Instruments in Arosa............................................ 39 

5.1.6. Validation of TOMS and SBUV Satellite Instrument Ozone Data ............................... 39 

5.1.7. Tropospheric Ozone ................................................................................................... 41 

5.1.8. Ozonesonde Observations............................................................................................ 43 

5.1.9. Stratospheric Water Vapor........................................................................................... 44 

5.1.10. Long-Range Transport of Trace Gases......................................................................... 44 

iii 
5.2. Special Projects . .... .... .... .... .... ............ .... .. .. .... ........ .................... .... .... .... ........ ........ .... ........ .... ... 48 

5.2.1. Nephelometer Comparison at MLO ............................................................................. 48 

5.2.2. Front Range Lidar, Aircraft, and Balloon Experiment.................................................. 49 

5.2.3. First Ground-Based Intercomparison of SBUV-2, S/N-2, and Dobson 

Spectrophotometer 83 ... .... .. ....... ... .... ............ ........ .... ........... ..... ........ .... .... .... .. .. .... ... 51 

5.2.4. Stratospheric Water Vapor Measurements in the Polar Regions................................... 52 

5.3. References ................................................................................................................................ 53 

6. Acquisition and Data Management ................................................................................... .... ............... 55 

6.1. Continuing Programs ............................................................................................. ................... 55 

6.1.1. Station Climatology .................................................................................................... 55 

6.1.2. Data Management ..... .... ........ .... .... .... .... .... .. .. ........ ........ ........ ........ .... ..... ... ... . ........ .... ... 58 

6.2. References ..... .... ........ ........ .... ........ .... .... ........ .... .... .... ........ ........ ........ .... ............. ... .... .... .. .. .... ... 62 

7. Nitrous Oxide and Halocarbons Group ................................................................................................ 63 

7 .1. Continuing Programs . ............ ........ ........ ........................ ... . ........ ........ ........ .... .. ...... .... ........ .... ... 63 

7 .1.1. Flask Samples .. .. .. . . .. .. .. . ... .. .. . . . . .. .. .. .. . . .. .. . . .. . . ... . ... . .. . . ... . ... . .. . . ... . . .. . .. .. . . .. . . . . .. .. .. .. . . .. . ... .. . 63 

7.1.2. RITS Continuous Gas Chromatograph Systems at CMDL Baseline Stations ............... 64 

7 .1.3. Low Electron Attachment Potential Species................................................................. 66 

7 .1.4. Ora vi metric Standards.................................................................................................. 67 

7.2. Special Projects......................................................................................................................... 67 

7 .2. 1. Alternative Halocarbon Measurements......................................................................... 67 

7 .2.2. Soviet-American Gas and Aerosol Experiment (SAG A III).......................................... 69 

7.2.3. Airborne Gas Chromatograph For Atmospheric Species (ACATS)............................... 70 

7.3. References ................................................................................................................................ 71 

8. Director's Office ........................................................................................................................... ....... 72 

8.1. Low-Level Temperature Inversions of the Eurasian Arctic and Comparisons With 

Soviet Drifting Station Data ........................................ ........................................ ................... 72 

8.1.1. Introduction.................................................................................................................. 72 

8.1.2. Results: Sea Ice/Land Comparisons.............................................................................. 72 

8.1.3. Summary and Conclusions........................................................................................... 74 

8.2. Boundary Layer Ozone Fluctuations Related to Organobromine Photochemistry 

in the Springtime Arctic ......................................................................................................... 74 

8.2.1. Introduction ................................................................................................................. 74 

8.2.2. Experimental .................................................... ........................................ ................... 75 

8.2.3. Results ..................................................................................................... ................... 76 

8.2.4. Discussion and Summary ......................................................................... ................... 78 

8.3. References ................................................................................................................................ 79 

9. Cooperative Programs . .. .. .. . .. . . ... . . . . . .. . . .. . .. .. .. .. . .. . .. .. .. . . . .. . .. . . .. .. .. .. . .. . .. .. . .. . ... . .. .. .. .. ... . .. .. .. .. . .. . .. .. .. . .. . .. . ... .. . 81 

Continuous Aerosol Monitoring with the Epiphaniometer at MLO 

U. Ba/tensperger, H.W. Gaeggeler, and D.T. Jost ....................................................... 81 

Antarctic Ultraviolet Spectroradiometer Monitoring Program 

C.R. Booth, T. Lucas, J. Morrow, D. Neuschu/er, J. Tusson, and J. Yeh ...................... 83 

A Case Study of the Stable Lower Atmospheric Boundary Layer at Barrow, Alaska ................ . 

T.K. Cheung ................................................................................................................ 85 

Artificial Windshielding of Precipitation Gauges in the Arctic 

G.P. Clagett ................................................................................................................ 87 

UVB Monitoring Data from Mauna Loa 

DL. Correll, C. Clark, R. Goodrich, and D. Hayes ..................................................... 88 

South Pole Lidar 

G. Fiacco, M. Cacciani, P. DiGiro/amo, A. DiSarra, and D. Fua ................................ 89 

Total Nitrate Variations at Mauna Loa 

B.J. Huebert and G.L. lee..................................... ....................................................... 91 

iv 
Temperature Inversions in the Canadian Arctic 

J.D. Kahl, M.C. Serreze, and R.C. Schnell................................................................... 92 

The Historical Arctic Rawinsonde Archive 

J.D. Kahl, M.C. Serreze, and R.C. Schnell ................................................................... 95 

Trajectory Forecasting for Misers Gold 

JD. Kahl,R.C. Schnell, andP.J. Sheridan............................................... ................... 99 

Trace Gases Over Hawaii; Concentrations, Trends, and Vertical Gradients 

MA.K. Khalil and RA. Rasmussen.............................................................................. 102 

Radioactivity in the Surface Air at BRW, MLO, SMO, and SPO 

R.J. Larsen and C.G. Sanderson .................................................................................. 105 

Zonal Representativeness of Cape Grim C02 Measurements 

G.I. Pearman, D.J. Beardsmore, R.J. Francey............................................................. 107 

Aerosol Constituents at American Samoa: May-June 1990 

D.L. Savoie, J.M. Prospero, R. Arimoto, and R.A. Duce .............................................. 109 

Analysis of MSA and nss so; at MLO 

B.B. Shurtleff, X.Y. Cai, and W.H. Zoller .................................................................... 112 

Stable Lead Isotope Ratios at Barrow, Alaska 

W.T. Sturges, R.C. Schnell, J.F. Hopper, and L.A. Barrie ........................................... 114 

Atmospheric Bromine Measurements at Barrow, Alaska, using a Sequential 

Filter Pack and Carbon Tube Sampler 

W.T. Sturges, R.C. Schnell, G.S. Duton, S.R. Garcia, and J.A. Lind ............................ 117 

Radon as a Baseline Selection Criterion at Mauna Loa Observatory 

S. Whittlestone, L.P. Steele, and S. Ryan ..................................................................... 120 

Seasonal Amplitude Variations in C02 in the Northern Hemisphere 

T.P. Whorf and CD. Keeling ....................................................................................... 124 

10. International Activities, 1990 ............................................................................................................... 127 

11. Publications and Presentations by CMDL Staff, 1990 .......................................................................... 129 

12 . Acronyms and Abbreviations . ...... ...... ... .... .... .... .... . ... .. .. .... ................ .... . .. . . . .. .... .... ... . .... ... . ...... ...... .... ... 131 

v 
Director's Office 

Eldon E. Ferguson, Director 

James T. Peterson, Deputy Director 

David Hofmann, Senior Scientist 

Donna Leise, Administrative Officer 

Sandra Howe, Administrative Assistant 

Ellen Hardman, Secretary 

Rita Rosson, Editorial Assistant 

Special Projects 

Russell Schnell, CIRES 

Mark Serreze, CIRES 

Scott Sewell, CU Grad Student 

Patrick Sheridan, NRC Post Doctorate 

Spencer Shiotani, CU Work Study 

Donna Smith, CU Work Study 

Matthew Steiman, CU Work Study 

William Sturges, CIRES 

Brett Taylor, CU Work Study 

Acqulstlon & Data Management 

Group 

Gary Herben, Chief 

Sheri Cox, Secretary 

Pamela Grisham, Secretary 

Mark Bieniulis, CIRES 

Michael Ellis, Physical Science Aid 

Joyce Harris, Computer Specialist 

James McCutcheon, CIRES 

Gregory Orleans, Physical Science Aid 

Kenneth Thaut, Electronic Technician 

Atmospheric Radiation Monitoring 

Group 

John DeLuisi, Chief 

Marilyn Van Asche, Secretary 

Barry Bodhaine, Meteorologist 

Paul Chilson, Physical Science Aid 

Ellswonh Dutton, Meteorologist 

Rudy Haas, Mathematician 

Fred Kreiner, CIRES 

David Longenecker, CIRES 

Donald Nelson, Meteorologist 

Gayland Pounder, Physical Science Aid 

Patrick Reddy, CIRES 

Kevin Schlatter, CIRES 

Michael Shanahan, Physical Science Aid 

Scott Siao, Physical Science Aid 

Roben Stone, CIRES 

Barbara Thomson, Physical Science Aid 

CMDL Staff, 1990 

Carbon Cycle Group 

Pieter Tans, Chief 

Lee Prendergast, Secretary 

Thomas Conway, Research Chemist 

Wyatt Coy, CIRES 

Edward Dlugokencky, CIRES 

Douglas Guenther, CIRES 

Brian Hirsch, CO-OP 

Duane Kitzis, CIRES 

Patricia Lang, Physical Scientist 

Terry Lesoing, CO-OP 

Russell Manin, CIRES 

Kenneth Masarie, CIRES 

Paul Novelli, CIRES 

Christopher Platt, CO-OP 

L. Paul Steele, CIRES 

Gregory Summers, CO-OP 

Kirk Thoning, Physicist 

Anthony Vaughan, Physical Science Aid 

Lee Waterman, Research Chemist 

Ozone Group 

Walter Komhyr, Chief 

Lee Prendergast, Secretary 

Brandon Bird, WAE 

Roben Evans, CIRES 

Roben Grass. Physicist 

Gloria Koenig, Computer Programmer 

Jeffrey Lathrop, CO-OP 

Kent Leonard, CIRES 

Samuel Oltmans, Physicist 

Michael O'Neill, CO-OP 

Daniel Opperman, CO-OP 

Christopher Platt, Physical Science Aid 

Frank Polacek, ill, Meteorological 

Technician 

Brandon Strong, CU Student 

Dorothy Quincy, CIRES 

James Wendell, Electronic Technician 

vi 

Nitrous Oxide and Halocarbons 

Group 

James Elkins, Chief 

Marilyn Van Asche, Secretary 

Christina Brunson, CIRES 

James Butler, Research Chemist 

Thomas Baring, Physical Science Aid 

Scott Cummings, Physical Science Aid 

Timothy Gilpin, NRC Post Doctorate 

Brad Hall, Research Chemist 

Bradley Halter, CIRES 

Garry Holcomb, CIRES 

Thayne Thompson, Physicist 

Jeffrey Sczechowski, CIRES 

Thomas Swanson, CIRES 

Observatory Operations 

Bernard Mendonca, Chief 

Sheri Cox, Secretary 

Pamela Grisham, Secretary 

Denise Theede, Program Clerk 

Barrow • Daniel Endres, Station Chief 

Christopher Churylo, Electronic 

Technician 

Timothy Quakenbush, 

Electronic Engineer 

Maun a Loa - Elmer Robinson, Director 

Judith Pereira, Program Suppon 

Technician 

John Chin, Physicist 

Thomas Defoor, Electronic Engineer 

Barbara Kerecman, Data Clerk 

Darryl Kuniyuki, NOAA Jr. Fellow 

Steven Ryan, Physical Scientist 

Mamoru Shibata, Electronic Technician 

Tracie Yokoi, Physical Science Aid 

Alan Yoshinaga, Chemist 

Samoa • Carl Farmer, Station Chief 

M. Emily Wilson-Godinet, 

Electronic Technician 

South Pole· Carl Groeneveld, 

NOAA Corps 

Fred Schrom, Electronic Technician 

John Lowell, NOAA Corps 

Michael O'Neill, Physicist 
CMDL Station Information 

Name: Barrow (BRW) Mauna Loa (MLO) 

Latitude: 71.323 19.539 

Longitude: 156.609 155.578 

Elevation: Sm 3397 m 

Time Zone: GMT-9 GMT-10 

Office Hours: 8:00 am-5:00 pm 8:00 am-5:00 pm 

Telephone 

Office hours: (907) 852-6500 (808) 961-3788 

Fax: (907) 852-4622 (808) 961-3788 

Postal Address: Officer in Charge U.S. Dept. of Commerce 

NOAA/ERL/CMDL NOAA - Mauna Loa Observatory 

Pouch 8888 P.O. Box 275 

Barrow, AK 99723 Hilo, HI 96720 

Freight Address: Same as above U.S. Dept. of Commerce 

NOAA - Mauna Loa Observatory 

154 Waianuenue Ave. 

Hilo, HI 96720 

Name: Samoa (SMO) South Pole (SPO) 

Latitude: -14.232 -89.997 

Longitude: 170.563 -102.0 

Elevation: 77 m 2841 m 

Time Zone: GMT-11 GMT +12 

Office Hours: 8:00 am-5:00 pm 8:00 am - 5:00 pm 

Telephone: 

Office hours: 011 (684) 622-7455 Relayed through CMDL Boulder 

After hours: 011 (684) 699-9953 

Fax: 011 (684) 699-4440 

Postal Address: U.S. Dept. of Commerce Officer in Charge, 

NOAA - GMCC Samoa Observatory NOAA/CMDL Clean Air Facility 

S-257 

Pago Pago, American Samoa 96799 South Pole, Antarctica 

PSC 468 Box 402 

FPO AP 96598-5402 

Freight Address: Same as above Sarne as above 

vii 

CLIMATE MONITORING AND DIAGNOSTICS LABORATORY 

N0.19 

SUMMARY REPORT 1990 

1. Introduction 

January 1990 marked the transition of the former 

Geophys:cal Monitoring for Climatic Change (GMCC) 

program into the Climate Monitoring and Diagnostics 

Laboratory (CMDL). CMDL was formed as part of an ERL 

reorganization, which combined the GMCC activities with 

those of the Climate Research Division of the Air Resources Laboratory. Dr. Eldon Ferguson was named the 

first Director of CMDL. Another significant personnel 

change was the recruitment of David Hofmann as the 

CMDL Chief Scientist. Dr. Hofmann, formerly with the 

University of Wyoming, brings added expertise to the 

Laboratory's aerosol and stratospheric ozone programs. 

Significant new program activities continue to be 

supported by the developing NOAA Climate and Global 

Change (C&GC) Program. New funding has been 

received for development and preparation of primary gas 

standards for halocarbons, C02 , CH4, and CO. We are 

working with the University of Colorado to begin 

monitoring of the 13C and 12C isotopes of C02 and CH4 . 

Planning began for vertical profile measurements from 

aircraft and very tall television transmitting towers for 

C02, CO, and halocarbons. Finally, C&GC is also 

supporting research on monitoring of the replacement 

halocarbons, those species expected to see increasing use 

in place of the traditional CFC-11, CFC-12, and CFC-113 

species. Regarding the Observatories, we are pleased that 

a new 5-year agreement with the National Science 

Foundation was accepted for continuation of our longterm monitoring program there. 

This Summary Report 1990, Number 19 continues the 

chronological numbering of the past, but includes the new 

Laboratory title. Similar to last year, this document does 

not include the activities of the Climate Research 

Division of the Laboratory. 
2. Observatory Reports 

2.1. MAUNA L OA OBSERVATORY 

E. R OBINSON 

2.1.1. OPERATIONS 

An important addition to the MLO program occurred in 

December when a radon (Rn) concentration monitor was 

placed in operation as part of the permanent suite of 

monitoring instruments at the observatory. This radon 

monitor was constructed for CMDL and installed at MLO by 

personnel of the DOE Health and Safety Laboratory, New 

York. This CMDL Rn monitor joined the ANSTO 

Cooperative Rn monitoring program which has been 

operating at MLO since May 1989. 

Another important instrumentation upgrade was made in 

July when the venerable G.E. CNC unit was finally retired 

and the CN monitoring task was taken over by the TSI CNC 

monitoring system. The TSI has undergone an extensive 

period of intercomparison with the G.E. CNC and the Pollak 

CNC before it was accepted as the MLO CNC for long term 

records. The substitution of the TSI for the G.E. CNC has 

simplified the required maintenance schedule for CN 

measurements. 

Distinguished visitors in 1990 included Dr. John Knauss, 

Under Secretary of the Department of Commerce and 

Administrator of NOAA. He paid a 2-day visit to Hilo and 

MLO in July. November 30, 1990, marked the retirement of 

Mamoru "Al" Shibata after almost 30 years of government 

service. He started government service with ESSA (now 

NOAA) and the National Weather Bureau in 1961. Al had 

assignments in the South Pacific, in the Panama Canal Zone, 

and at ARL-Las Vegas before transferring back to Hawaii to 

work at MLO in 1972. The CMDL program will miss his 

dedication and many technical skills, while his associates at 

MLO will miss his warm disposition, subtle humor, and 

friendship. 

March 1990 will be remembered as the month of the big 

snow at MLO. The storm hit on February 27 and continued 

through March 1. The storm left 0.5-1.0 m drifts across the 

upper portions of the MLO road. This was above about the 

3.0 km level. Several attempts to reach the observatory 

(even by 4-wheel drive vehicles) were unsuccessful until 

Tuesday, March 6, when two MLO staff members hiked in 

and were able to check station conditions. The station 

facilities and instrumenration were in good condition and 

many observations had continued under CAMS control 

throughout the storm isolation period. CAMS tapes had 

switched although chart rolls had run out, operating filters 

had run ex~a time, and moisture traps on the C02 analyzers 

had frozen up. These were not unexpected. On Friday, 

March 9, a 4-wheel drive truck got within 100 m of the lower 

visitor parking area and then the crew walked the rest of the 

way in. At this time most of the remaining instruments were 

reset and restarted in a normal operational routine. On 

Monday, March 12, it was possible to drive to the 

observatory in the MLO station wagon, although it was 

necessary to use tire chains to get up the last hill above the 

lower parking area. Full operation of the MLO program 

was resumed on March 12. This storm was the most severe 

in the 34-year history of MLO. The "old timers" cannot 

remember a situation where snow blocked access to MLO 

for more than 2 consecutive days, compared to this storm's 

1-2 weeks inaccessibility. It is encouraging to note that the 

MLO operations survived this event in good shape and with 

a high percentage of data recovery. 

The east rift zone eruption of Kilauea Volcano continued 

during the year. Shifting areas of flow activity resulted in 

considerable property damage in the Kalapana and Kaimu 

areas. Because of the distance and direction to this eruption 

area, the local wind patterns, and the topography, this 

eruption ac tivity is not believed to have any significant 

impact on the ongoing MLO monitoring program as was 

described previously [Komhyr and Rosson, 1990). 

2 .1 .2. PROGRAMS 

Table 2. 1 summarizes the major CMDL and cooperative 

programs carried out at MLO during 1990. Although most 

of the programs listed in this table are continuations of 

similar listings in previous reports [e.g., see Komhyr and 

Rosson, 1990). there are several changes documented here. 

Perhaps the most important change, as noted in Section 

2. 1.1., was the addition of a continuous radon monitor in 

December 1990. This monitor was designed, constructed, 

and installed by the DOE, Health and Safety Laboratory. 

The sampling technique involves the collection of timeintegrated samples. Samples of 30-minute duration have 

generally seemed to be optimum. The radon record 

provides information useful for the evaluation of longrange transport from distant land areas. A number of 

observations were also removed from the MLO schedule. 

The G.E. CNC was discontinued in July, and now the TSI 

CNC provides the MLO CN record. There was more than a 

year of parallel data for these two instruments prior to the 

discontinuance of the G.E. CNC. The sulfur monitoring 

program for both total sulfur and S02 was discontinued in 

February. This program had been supported with the 

cooperation of the ARL Air Quality Group. The hygrothermograph at Kulani Mauka was also discontinued when 

the NWS lost interest in these data and in assisting in the 

maintenance of this station. Among the cooperative 

programs, the EPA support for programs of S02 bubbler 

2 

sampling and high-volume filter sampling was 

discontinued. A modified total suspended particle 

sampling program was designed and begun using the 

available high-volume filter samplers and the MLO 

chemistry laboratory to continue the basic TSP data record. 

The NADP/ISWS program of 7Be and 10Be precipitation 

analyses was discontinued early in the year. 
Gases 

co2 

Program 

C02, CH4 

CH4 

Surface 0 3 

Total 0 3 

0 3 profiles 

CFC-11, CFC-12, N20 

CFC-1 1, CFC-12, N20, 

CC14, CH3CC13 

N20 

Total sulfur gases 

S02 

Radon 

Aerosols 

Condensation nuclei 

Optical properties 

Stratospheric aerosols 

Black carbon 

Total suspended particles 

Solar Radiation 

Global irradiance 

Direct irradiance 

Diffuse irradiance 

Turbidity 

tJltraviolet radiation 

Me/lorology 

Air temperature 

Temperature gradient 

Dewpoint temperature 

Relative humidity 

Pressure 

Wind (speed and direction) 

Precipitation 

Total precipitable water 

Precipitation Chemistry 

pH 

Conductivity 

Chemical components 

TABLE 2.1. Summary of Measurement Programs at MLO in 1990 

Instrument 

Siemens Ultramat-3 IR analyzer 

3 -L glass flaskst 

O.S-L glass flasks, through analyur 

O.S-L glass flasks, P3 pump unitt 

Carle automated GC 

Dasibi ozone meter 

Dobson spectrophotometer no. 76 

Dobson spectrophotometer no. 76 

(automated Umkehr method) 

Balloonbome ECC sonde 

300-mL stainless steel flasks 

HPS890 automated GC 

Shimadzu automated GC 

CSI flame photometric analyzer• 

TECO pulsed fluorescence analyur• 

2-filter system 

Pollak CNC 

G.E. CNC• 

TSICNC• 

Four-wavelength nephelometer•: 

450, SOO, 700, 850 nm 

Lidar, 694.3 nm 

Aethelometer 

High-volume sampler 

Eppley pyranometers with Q, 

OG 1, and RG8 filters 

Eppley pyrheliometer (2) with Q filter• 

Eppley pyrheliometer with Q, OGI, 

RG2, and RG8 filters 

Eppley/Kendall active cavity 

radiometer 

Eppley pyrgeometer with shading disk 

and Q filter• 

J-202 and J-314 sunphotometers with 

380-, SOO-, 778-, 862-nm narrowband filters 

PMOD three-wavelength sunphotometer•: 

380, SOO, 778 nm; narrowband 

UV radiometer (erythema) 

Aspirated thermistor•, 2- and 40-m heights 

Max.-min. thermometers, 2-m height 

Hygrothermograph 

Aspirated thermistors•, 2- and 40-m heights 

Dewpoint hygrometer•, 2-m height 

Hygrothermograph 

Capacitance transducer• 

Mecurial barometer 

Bendi.x Aerovane•, 8.S- and 40-m heights 

Rain gauge, 8-in 

Rain gauge, 8-int 

Rain gauge, tipping bucket• 

Foskett IR hygrometer• 

pH meter 

Conductivity bridge 

Ion chromatograph 

3 

Sampling Frequency 

Continuous 

I pair wk-t 

I pair wk-1 

I pair wk-1 

I sample (24 min)-1 

Continuous 

3 day·I, weekdays 

2 day· 1 

I wk· 1 

I pair wk·1 

1 sample (h)· 1 

I sample (h)-1 

Discontinued 2/90 

Discontinued 2/90 

Continuous 

I day·1 

Discontinued 7 (31/90 

Continuous 

Continuous 

I profile wk·l 

Continuous 

2 samples (mo)·t 

Continuous 

Continuous 

3 day·1 

I mo·1 

Continuous 

3 day·1 

Continuous 

Continuous 

Continuous 

I day· 1 

Continuous 

Continuous 

Continuous 

Continuous 

Continuous 

S wk-I 

Continuous 

S wk·1 

I wk· 1 

Continuous 

Continuous 

Daily 

Daily 

Daily 
TABLE 2.1. Summary of Measurement Programs at MLO in 1990--Continued 

Program 

Cooperative Programs 

C01 (SIO) 

col. 13C, NlO (SIO) 

Surface S01 (EPA) 

C01, CO, CH4, 13C/12C (CSIRO) 

C01 , CH4, other trace 

gases (NCAR) 

Total suspended particles (DOE) 

Turbidity (AES Canada) 

CH4 ( 13C/12C) (Univ. of Washington) 

Total suspended particles (EPA) 

Ultraviolet radiation (Smithsonian) 

Solar aureole intensity (CSU) 

Precipitation collection (DOE) 

Precipitation collection for 7Be and lOBe 

Precipitation collection for organic acid 

analysis (Univ. of Virginia) 

Wet-dry deposition (ISWS, NADP) 

Aerosol chemistry, upslope-downslope 

discrimination (Univ. of Washington) 

Aerosol chemistry (Univ. of Calif.-Davis) 

Various trace gases (OGC) 

HN03, HCl vapor, aerosols (URD 

Radon (ANSTO) 

Aerosol surface area (PSI) 

Formation of 3He (WHOI) 

All instruments are at MLO unless indicated. 

Instrument 

Applied Physics IR analyzer 

5-L evacuated glass flaskst 

Chemical bubbler system 

Pressurized glass flask sample 

Evacuated stainless steel flaskst 

High-volume sampler (l filter wk·1) 

Sonotek sunphotometer no. 5698 

35-L evacuated flask 

High-volume sampler 

8-wavelength UV radiometer: 290-325 nm; 

narrowband 

Multi-aperture tracking photometer: 

2, 5, 10, 20, 30" fields of view 

Exposed collection pails 

Aerochemetric automatic collector 

Aerochemetric automatic collector 

Aerochemetric automatic collector and 

weighing-bucket rain gauge 

Nuclepore filters 

Programmed filter sampler 

Stainless steel flaskst 

Filter system 

Aerosol scavenging of Rn 

Epiphaniometer 

Closed cylinder 

•Data from this instrument recorded and processed by CAMS. 

tMLO and Kumukahi. 

tKulani Mauka 

Sampling Frequency 

Continuous 

l pair wk·1 

Discontinued 5/90 

l mo·1 

l pair wk·1 

Continuous 

1-3 day·1 

l mo·1 

Discontinued 5/90 

Continuous 

Continuous 

Integrated monthly sample 

Discontinued 1/90 

Collection after each 

rain event 

Integrated 7-day sample 

Continuous 

Integrated 3-day sample 

1 continuous and l downslope sample (3 days)·1 

l set wk·l (3 flasks) 

Daily, 2000-0600 LST 

Continuous; integrated 30-min 

samples 

Continuous; integrated 30-min 

samples 

Continuous 12-mo ambient 

exposure from 1/90 

Carbon Dioxide 

The CMDL Siemens Ultramat-3 IR C01 analyzer and the 

SIO Applied Physics IR C01 analyzer operated in parallel 

without major problems throughout the year. Routine 

maintenance and calibrations were done on both 

instruments on schedule. In May 1990, the air sampling 

pumps for the SIO C01 system were changed to Air Cadet 

pumps that use a plastic pump head and nitrile diaphragms. 

The original pumps used by SIO since 1958 were Dyna 

Pumps with neoprene diaphragms. In September a small 

precision temperature controller was added to the SIO 

Applied Physics analyzer. The preliminary provisional 

yearly average for MLO C01 concentration for 1990 was 

354.3 ppm. The C01 annual growth rate between 1989 and 

1990 was approximately 1.5 ppm. Outgassing from the 

volcanic vents at the Mauna Loa caldera and along the 

northeast rift zone at Mauna Loa continued to cause 

periodic observable disturbances in some of the C01 data 

record. As in prior years, these venting events occurred 

mostly between midnight and 0800 LST of the following 

day during the downslope wind regime. The erratic 

concentration data characterized by extreme variability 

resulting from venting events were easily identified by 

visually scanning the chart records or by setting up a 

computerized data screening procedure, and thus they have 

been separated from the clean-air record without difficulty. 

The frequency of monthly occurrences of observable 

outgassing from volcanic vents on Mauna Loa for 1990 are 

listed in Table 2.2. Such venting episodes were detected 

mainly on the basis of criteria for C02 concentration, C01 

variability, and wind sector. The criterion for the C01 

standard deviation screening was 1.0 ppm, which is the 

value suggested by Thoning et al. (1989). The 1990 total 

venting of 48 hours as shown in Table 2.2 is significantly 

less than the 84 hours noted in 1989 [Komhyr and Rosson, 

1990) and the 200 hours recorded in 1988 [Elkins and 

Rosson, 1989). 

4 

The weekly C01, CH4 and other gas sampling programs 

using flasks at MLO and at Cape Kumukahi were carried out 

according to schedule through the year without problems. 
TABLE 2.2. Estimated Frequency of MLO Venting Effects* 

Jan. Feb. March April May June July Aug. Sept. Oct. Nov. Dec. Year 

Total time (hours) 7 3 5 2 4 6 0 3 3 5 9 48 

•Criteria: C02 SD (!J.0 ppm; wind direction sector 135' -225'; wind speed >!.35 m s·I. 

Methane 

The Carle automated GC system was in continuous 

operation throughout the year and provided CH4 data on the 

basis of a grab-air sample taken every 24 minutes. No major 

problems were encountered in this program. The CH4 data 

continued to show clearly defined cycles of varying 

frequencies. The typical diurnal cycle was correlated with 

the up and downslope winds with the marine boundary layer 

air having the higher CH4 concentratio.ns. There were also 

multi-day or synoptic-scale cycles apparently related to air 

mass source regions. Finally, there is still a gradual upward 

trend in CH• concentrations throughout the year. 

Ozone 

The 1990 MLO 0 3 monitoring program continued to 

consist of three phases: continuous MLO surface monitoring 

using a Dasibi model 1003-AH UV absorption ozone 

monitor; daily total ozone and Umkehr ozone profile 

measurements using a computer-based automated Dobson 

instrument (Dobson no. 76); and ozone profile measurements 

based on regular ascents of balloon-borne ECC ozonesondes 

from the NWS station at the Hilo airport. 

The 1990 ozonesonde operations were programmed into a 

schedule of three flights per month. The program used 

2000g rubber balloons from January 1 to July 5 ·and 1500g 

rubber balloons after July 5. In the first part of the year, 16 

successful flights were made and in the latter period (i.e., 

after July 5), 15 fli ghts were successful. During the year 

there was a total of 35 ozonesonde flights, but 4 failed after 

l aunch before useful data could be obtained resulting in a 

total of 3 1 successful ozonesonde launches. During the 

January through July 5 period when the larger 2000g 

balloons were used, the median altitude reached by the 

ozonesondes was 6.1 mb (34.6 km) and 75% of the flights 

rose to over 34 km. After July 5, when smaller 1500g 

balloons were used, the median flight altitude for the 15 

successful flights was 7 .5 mb (33.2 km). In this part of the 

program 75% of the flights went to an altitude of 32 km or 

higher. The maximum ozone concentration over Hawaii is 

typically found at around 25 km [Bodhaine and Rosson, 

J 988, pg 41]; thus these ozonesonde flights were able to 

provide good information on the ozone layer over Hawaii 

even though the 40 km flight altitudes reached in previous 

years could not be achieved by the smaller rubber balloons. 

As noted above, total 0 3 and Umkehr 0 3 profiles using 

automated Dobson no. 76 were a regular part of the MLO 

observation routine in 1990. There were no major breaks in 

this record due to prolonged instrument problems. Weather 

conditions were favorable for Dobson direct sun 

observations on 75% of the observatory observation days. 

During the 1990 summer, a side-by-side calibration program 

was carried out using the WMO world standard Dobson no. 

83 and the observatory Dobson instrument. 

The third part of the MLO ozone monitoring program is 

the continuous operation of the Dasibi ozone monitor. This 

instrument performed in a very satisfactory manner throughout the year, and it provided a continuous record of 

station-level ozone concentrations for the year. The air inlet 

from the main sampling stack was unchanged from prior 

years. 

Halocarbons and Nitrous Oxide 

There was a major improvement in the RITS GC system 

in October when the newly developed RITS PLOT program 

was installed in the MLO system. With RITS PLOT it is 

possible to obtain a printout of GC results for the past 30 

days and thus to review the performance of the system and to 

correlate RITS gas concentrations with other factors 

monitored at MLO. The RITS system was upgraded during 

the year to provide hourly ambient air concentrations in 

place of the once every 3-hour samples obtained previously. 

The RITS sample gases were expanded to include CFC-113 

as well as N20, CFC-11, CFC-12, cc1 •• and CH3CC13• 

Although this complex gas chromatographic system was not 

trouble free during the year, the problems that did occur 

could usually be corrected with little resulting downtime, 

and no catastrophic failures occurred. The RITS PLOT 

results appear to show both weak diurnal cycles and 

longer-term or multi-day synoptic scale concentration 

variations in the several CFC compounds, but not in N20. 

This is not unexpected. 

s 

Radon 

The MLO radon program began in December with the 

installation of a radon monitor built by the DOE, Environmental Measurements Lab. The monitor operates on the 

two-filter principle using a 330-L delay tank and a 380-L 

minute flow rate. Air is sampled from the top of the 40-m 

tower via 7 .5 cm diameter inlet tubing. In the monitor the 

air stream passes through a filter which removes all the 

ambient "daughters" but allows the inert radon gas to pass. 

The radon then enters the delay tank during which new 

daughters are produced. These are collected on a second 

filter, and the resulting alpha activity on the filter is 

monitored by a scintillation counter. The second filter 

consists of a filter roll that advances frame by frame. 

Successive frames are first exposed to the air stream and 

then monitored. Sampling and monitoring periods of 30 
minutes have proven to be effective in tracking the radon 

concentration patterns at MLO. 

Preliminary analysis of the data illustrated by Figure 2.1, 

shows periods of increased radon typically lasting several 

days, such as after December 25 that coincided with 700 mb 

isobaric back trajectories indicative of fast transport of air 

from Asia. Daytime radon increases were frequently 

coincident with periods of upslope winds. This probably 

indicated radon emanating from lower altitude island soils. 

December 15 is a clear example of this local or islanddominated pattern. The radon scale in Figure 2.1 is given in 

scintillation counts per 30-minute sample period. A 

calibration program is being carried out to convert this basic 

instrument output to more conventional r adon concentration 

units. 

Solar Radiation 

The solar radiation measurement program in 1990 was 

unchanged from previous years. Tracking pyrheliometer no. 

2119 was replaced by no. 16657 in April following a several 

month period of continuing sensitivity loss which reached 

3%. Eight active cavity comparisons were performed in 

early 1990. The instrument was then shipped to Boulder and 

Switzerland for calibrations from August to December. 

Sunphotometer calibrations were made on 15 days, during 

which 85 instrument calibrations were performed. Daily 

observations with the two MLO sunphotometers and the 

filter wheel NIP continued throughout the year. 

Aerosol Monitoring 

The MLO aerosol monitoring programs underwent a long 

anticipated change in July when the G.E. CNC was taken out 

of service, and the continuous MLO CN record was 

transferred to the TSI CNC. The TSI unit is a continuous 

expansion CNC in which condensation occurs in a butyl 

alcohol vapor chamber and single particle counting statistics 

are used as a basis for the CN concentration calculation. The 

Mauna Loa ObeervatOfy Radon Data 

l11 I 

~,I 

J'~ ~ ~ ~WI i .. t.m111 y .,, ., lTf ~ ' " I 

-0 a 11 1a ao 11' • DECEMBER. 1 tilQO (I.ST) 

Fig. 2.1. Initial MLO radon concentration data from the CMDL/ 

DOE two-filter monitor. Concentration scale is in relative units of 

scintillation counts per 30-minute sample. 

TSI output is recorded by the ASR CAMS. The aethalometer unit, initially put into service in 1989 [Komhyr and 

Rosson, 1990] was modified in early 1990 so that both 

control and data recording were carried out by a dedicated 

lap-top computer. This computer setup substituted for 

CAMS control, which had proved to be unsatisfactory for the 

TSI instrument. With this change in the system, the 

aethalometer record began to exhibit very interesting features 

both in terms of short-term and long-term cyclic variations. 

The 4-wave length nephelometer was in continuous service 

during the year with a minimum of downtime. 

6 

The measurements of stratospheric aerosol concentrations 

and profiles using the MLO ruby lidar system continued 

throughout the year. During the year a total of 32 lidar 

aerosol profile observations were made. The lidar program 

was hampered to some extent in the months of September 

throligh December by a relatively high frequency of cloudy 

weather. During 1990 the stratosphere appeared to have 

approached a clean equilibrium background condition and no 

new injections of volcanic aerosol layers were detected. 

Figure 2.2 shows the MLO lidar record from its beginning in 

1974 through 1990. Major volcanic eruptions causing 

probable stratospheric layers are also indicated. Note in 

particular the long decay time associated with the massive 

1982 eruption of the Mexican volcano El Chichon. Figure 

2.3 shows the 4-year lidar record from 1987 through 1990. 

The average stratospheric (16-33 km) non-Rayleigh 

backscatter, i.e., aerosol backscatter, exhibited little change 

during 1989 and 1990. The differences between 1989 and 

1990 are not statistically significant and, as noted above, 

probably represent an equilibrium background aerosol 

concentration value during this 2-year period. 

During a visit to Hilo by the Soviet research ship Korolev 

in February, it was possible to make an intercomparison of 

the Soviet lidar system on the ship and the MLO lidar. 

Although the two instruments were separated by both 

distance and altitude, the results of the intercomparison 

10-i MALINA LOA OBS. 

"' ., 

"' z 

INTEGRATED NRBS 

16KM - 33KM 

OCT'74 THRU DEC'90 

YERR 

Fig. 2.2. MLO stratospheric aerosol lidar observations and major 

volcanic eruptions, 1974-1990. 
. ... 

1985 1956 

MAUNA LOA OBS. 

INTEGRATED NRBS 

16KM - 33KM 

1987 1988 1989 1930 

Fig. 2.3. MLO stratospheric aerosol lidar observations, 1985-1990. 

Note the relatively stable stratospheric background since about 

January 1989. 

experiment were very favorable. Figure 2.4 shows the 

results of this experiment. The divergence below 16 km is 

not considered to be important and probably results from 

data processing variations. 

Meteorology 

The routine program of wind, temperature, dewpoint, and 

atmospheric pressure was carried out during 1990 with few 

problems. There were no major changes in the 

meteorological observation program. One minor change was 

the discontinuance of the hygrothermograph data at Kulani 

Mauka when the NWS dropped their support for temperature 

and humidity from this station. Rainfall data are still 

collected at Kulani Mauka on a weekly basis, however. 

Precipitation Chemistry 

Direction and support for the MLO precipitation chemistry program by ARL was discontinued this year. In June a 

modified program of precipitation chemistry collection and 

35 

30 

t5 

MLO LIOAR DATA 

AK. KOROLEV DATA 

0'"-~~..__~~..___..~_._~~--'-~~_._~..__._ ~-' 

0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 

R 

Fig. 2.4. Results of an intercomparison experiment between the 

MLO lidar system and the U.S.S.R. lidar system installed on the 

Soviet ship Akademik Korolev. The experiment was carried out on 

the evening of February I 0, 1990. 

7 

analyses was continued within the basic MLO operational 

routine. This program consists of a weekly integrated 

precipitation sample from the Hilo NWS station and the 

collection of precipitation event samples at MLO. Analyses 

of these samples are done in the Hilo laboratory for pH, 

conductivity, and several ions using currently available 

equipment. 

Cooperative Programs 

Table 2.1 lists a total of 20 long-term programs which 

were operated at MLO for other investigators and organizations. These are the cooperative programs. Most of the 

listed programs are continuations from 1989 and prior years. 

One new program was started. This was for the Woods Hole 

Oceanographic Institute to determine whether JHe would be 

formed in water vapor contained in a closed cylinder when 

exposed for an extended time period to the cosmic ray 

radiation at MLO. A 1-year exposure is scheduled. The 

EPA programs of high-volume sampling for total suspended 

particles and S02 sampling using 24-hour bubblers, and the 

collection of weekly prec1p1tation samples for the 

determination of 7Be and tOBe by ISWS were discontinued 

during the year. The University of Washington program of 

flask samples was expanded to include the periodic 

collection of 30-L flask samples at high (2000 psi) pressure. 

As in most previous years, the MLO program also 

included several short period studies in which the 

investigators carried out programs of observations at MLO, 

usually with little need for assistance from MLO staff 

members. These programs are not listed in Table 2.1. 

2.2. BARROW 

D. ENDRES 

2.2.1. OPERATIONS 

A year of change best describes 1990 at BRW. A change 

in personnel took place in March with the arrival of a new 

electronics technician. A Fax machine was added to the 

station in January. The clean room was rewired during 

March to more evenly distribute the electrical load. The 

number of circuits in the clean room were doubled after 

several pieces of conduit were found to be warm from 

overloaded circuits. During the fall of 1989, a cutout on the 

power poles that supply power to the station exploded and 

had to be replaced. The local utilities company, BUECI, 

suggested that we upgrade the entire platform. We followed 

this recommendation in June after spring breakup and had 

the other two cutouts replaced along with the wiring between 

the transformers and the lines leading to the station. 

Duct work for the observatory cooling system was 

modified in March to account for the greater heat load 

produced by the addition of several new projects throughout 

the observatory building. 

A new telephone line was delivered and installed in May 

after the old line deteriorated to the point where repairs were 

no longer effective. The old line had been installed by 
rolling a standard 6-pair phone line out on the ground from 

the BRW observatory building to the DEW L; ~ hanger, a 

distance of about 3.2 km. After 18 years of exposure to the 

elements, the old line was showing severe wear from the 

ravages of time. Every spring during breakup, splices in the 

old line would fill up with water and telephone 

communications would degrade. GTE hung the new line on 

the power poles that run to UIC/NARL and it should last for 

a greater number of years since it cannot be run over by 

snowmachines or other tracked vehicles. Special than.ks 

should be given to the USGS in Fairbanks for their help in 

obtaining the new line and working with GTE to write a 

contract to install it. 

As in recent years, BRW was once again called on to 

serve as a training center for the new SPO crew. In the past, 

training time for each person was 2 weeks, this year it was 

increased to 1 month. In July, Boulder personnel from 

MASC and CMDL arrived to inspect the observatory 

building and collect data for a possible upgrade of the 

observatory facilities. At this time the road to the 

observatory was inspected and a local contractor was 

consulted as to the possibility of adding fill dirt to elevate 

the road which would improve road access during winter 

months. The current road is lower than the surrounding 

tundra and becomes impassable after most wind storms 

during the winter. A new contract to maintain the DEW Line 

was awarded to GEGS and on October 1 the new contractor 

arrived to take over operations. The old contractor, ITT, 

maintained a staff of 12 people on site; the new contractor 

uses 6 people, which for CMDL has resulted in less road 

maintenance. During the turnover to GEGS, several 

questions were raised about the actual boundaries of the 

DEW Line, NOAA, and USGS properties. As a result of 

these questions, a clerical error was discovered in the BLM 

files that brought to the attention of all agencies concerned, 

that the final transfer of property to NOAA and the USGS 

was still pending. The USGS in Fairbanks worked to resolve 

the problem and all paperwork effecting the transfer should 

be finalized at this writing. 

A warehouse fire at Prudhoe Bay caused concern in the 

village of Barrow when it was discovered that the warehouse 

contained Xylene, organic polymers, a mixture of HC! and 

HF!, and instruments containing radioactive substances. The 

fire burned overnight but as the winds were from the west, 

the effluent was blown away from Barrow and no 

contamination was detected at BRW. 

The BRW staff were called on to assist personnel from the 

North Slope Borough in technical and scientific matters. 

Technical expertise came in the form of repair and calibration of electronic equipment. BRW staff members appeared 

on locally-produced radio programs and answered questions 

concerning global climate change issues. 

Station vehicles continued to be a major drain on time and 

resources "of BRW personnel. Maintenance with the 1989 

Chevrolet pick-up truck ran the gamut from a tune-up to 

major front-end work. Wrong shock absorbers installed on 

the truck by the factory were discovered and replaced by the 

BRW staff. Continuing problems with the front-end 

8 

suspension indicated that it also may have been built 

incorrectly at the factory. The problem is still under 

investigation and review by GSA, the responsible government agency. Tires for the BRW vehicles were another 

major problem that hindered maintaining dependable 

transportation to and from the observatory. Tires on one 

truck became so weathered, that innertubes would squeeze 

out from cracks in the treads. Because of the cold arctic 

conditions, tires had to be ordered and replaced more 

frequently than in the lower 48 states. The 1979 GMC 

pick-up had a major tune-up and the carburetor was rebuilt 

by the BRW staff this year. After completing this 

maintenance on the 1979 truck, it was decided that it should 

be retired next summer and auctioned off by GSA. This is 

the last of the agency-owned vehicles at BRW; it has been in 

service for the past 11 years. Maintenance and repairs done 

on observatory vehicles are not inconsequential because of 

the lack of suitable working shelter and tools that are 

available to the BRW staff. The 1985 Chevrolet Suburban is 

awaiting shipment back to GSA in Anchorage after its 4-year 

stay in Barrow in accordance with our agreement with GSA. 

With regards to the snowmachines, the suspension was 

rebuilt on the Skandic 503 snowmachine in October in 

preparation for winter. The Skandic 377 snowmachine 

continues to run well requiring only a tune-up and a new 

drive belt. The Honda Big Red 3-wheeler received a tune-up 

and a new battery. A new federal ban on the sale of 

3-wheelers leaves us with doubts as to the number of years 

of service left in which we will be able to obtain parts. 

2.2.2. PROGRAMS 

Table 2.3 summarizes the 1990 measurement programs at 

BRW. Operational highlights were as follows: 

Aerosols 

A major change in the aerosol program was implemented 

in June with the addition of a TSI CNC. The TSI CNC is an 

alcohol-based CNC as opposed to the G.E. CNC which is 

water based. The G.E. CNC uses light attenuation by cloud 

formation due to particle growth from adiabatic expansion of 

CN in supersaturated air to measure CN. The TSI uses a 

single-particle-counting laser-diode optical detector to count 

individual droplets that have been supersaturated with 

n-butyl alcohol onto particles .014 microns and larger. By 

the end of the year, 6 months of a 12-month intercomparison 

had been completed with relatively few problems. The float 

which controls the alcohol level had to be reset to allow the 

TSI to run over a weekend without running out of alcohol. 

The only other occurrence of note was when a piece of 

insulation broke away from the condenser housing and 

entered the focusing nozzle, partiality blocking the flow that 

caused the TSI to give artificially low readings. The nozzle 

was cleaned and the instrument was returned to proper 

operation. The G.E. CNC ran well all year with only routine 

maintenance. The Pollak continues to serve as a field 

calibration standard for CNC measurements at BRW. The 

Pollak has been in operation at BRW since May 1976. 
TABLE 2.3. Summary of Measurement Programs at BRW in 1990 

Gases 

C02 

Program 

C02,CH4, CO 

CH4 

Surface 0 3 

Total 0 3 

CFC-11, CFC-12, CFC-113, N20 

CFC-11, CFC-12, CFC-113, N20, 

CC14, CH3CC13 

N20 

Aerosols 

Condensation nuclei 

Optical properties 

Black carbon 

Solar and Terrestrial Radiation 

Global irradiance 

Direct irradiance 

Terrestrial (IR) radiation 

Turbidity 

Albedo 

Meteorology 

Air temperature 

Dewpoint temperature 

Pressure 

Wind (speed and direction) 

Precipitation 

Precipitation Chemistry 

pH 

Conductivity 

Cooperative Programs 

Total surface particulates (DOE) 

Precipitation gauge (USDA) 

Magnetic fields (USGS) 

Various trace gases (OGC) 

C02, CH4 (NCAR) 

13C, 180, C02 (CSIRO) 

C02, 13C, N20 (SIO) 

CH4 (Univ. of Calif., Irvine) 

Earthquake detection 

(Univ. of Alaska) 

13CH4 (13C/12C) (Univ. of Washington) 

NO, NOY (Univ. of Alaska) 

Ultralow frequency waves (Univ. of Tokyo) 

Air chemistry ions, organic acid, halogens, 

nitrous oxides (CIRES) 

UV monitor (NSF) 

Inversion meteorology (NOAA/WPL) 

Air Chemistry 0 3 destruction (CIRES/NAS) 

Instrument 

URAS-2T IR analyur 

3-L glass flasks 

0.5-L glass flasks, through analyur 

0.5-L glass flasks, P3 pump unit 

Carle automated GC 

Dasibi ozone meter 

Dobson spectrophotometer no. 91 

300-mL stainless steel flasks 

HP5890 automated GC 

Shimadzu automated GC 

Pollak CNC 

G.E. CNC 

T.S.I. CNC 

Four-wavelength nephelometer 

Aethalometer 

Eppley pyranometers with Q and RG8 filters 

Tracking NIP 

Eppley pyrheliometer with Q, OGI, 

RG2, and RG8 filters 

Eppley pyrgeometer 

Sunphotometers with 380-, 500-, 778-, 

and 862-nm narrowband filters 

Eppley pyranometer and pyrgeometer 

Thermistor, 2 levels 

Max.-min. thermometers 

Dewpoint hygrometer 

Capacitance transducer 

Mercurial barometer 

Bendix Aerovane 

Rain gauge, tipping bucket 

pH meter (samples analyud at MLO) 

Conductivity bridge (samples analyzed at MLO) 

High-volume sampler (1 filter wk-1) 

Wyoming shielded precipitation gauge 

Magnetomeler 

Stainless steel flasks 

3-L stainless steel flasks 

5-L glass flasks 

5-L evacuated glass flasks 

Various stainless steel flasks 

Seismograph 

35-L stainless steel flasks 

Chemiluminscence 

Magnetometer 

Sample tubes and filters 

UV spectrometer 

Acoustic sounder 

Filter samples 

9 

Sampling Frequency 

Continuous 

I pair wk·1 

1 pair wk·1 

I pair wk·1 

1 sample (24 min)·l 

Continuous 

3 day-1 

I pair wk·1 

1 sample (3 h)·I 

l sample (3 h)·I 

I day·1 

Continuous 

Continuous 

Continuous 

Continuous 

Continuous 

Continuous 

Discrete 

Continuous 

Discrete 

Continuous 

Continuous 

1 day-1 

Continuous 

Continuous 

Discrete 

Continuous 

Discrete 

Discrete 

Continuous 

2mo·1 

Continuous 

1 set wk· 1 (3 flasks set -1) 

I pair wk'1 

I pair (2 wk)·1 

I pair wk·1 

1 set (3 mo)· 1 

Continuous, check 

site I wk·1, 

change tape l mo·I 

l (2 wk)-1 

Continuous 

Continuous 

1 day·1 

1 scan per 0.5 hour 

Continuous 

l day· 1 
The aethalometer ran well all year except for a burned out 

light bulb that was replaced in September. 

The nephelometer ran without any major problems for the 

entire year. 

Solar Radiation 

Solar radiation has been measured at BRW since 1976. 

The continuous downward global solar flux on a horizontal 

surface is measured in two spectral bands. In 1977 a normal 

incident pyrheliometer was added to measure the direct solar 

beam in four spectral bands. In 1988 an albedo rack was 

installed and measurements were made by a quartz 

pyranometer. The terrestrial IR budget, also started in 1988, 

is measured using an upward and a downward facing 

pyrgeometer. 

A new 2-m high rack for the solar radiation equipment 

was installed on the roof of the observatory during June 

1990. In 1986 and in 1990 it was noted that the albedo rack 

was used as a scratching post by caribou. The cyclic nature 

of the herd population, coupled with excessive snowfall 

throughout the North Slope during these 2 years, drove the 

herd far enough north to come in contact with BRW. There 

was no permanent damage to the rack and measurements 

were impacted minimally. All other equipment operated 

normally during the year. 

C02 

The weekly flask sampling program was accomplished 

throughout the year with no special problems. The 

URAS-2T IR analyzer operated without incident all year. 

The routine calibrations were performed on schedule and 

maintenance was performed as needed. A diaphragm was 

replaced in the pump used to supply ambient air to the C02 

system. A Siemens Ultramat-3 IR analyzer is expected to be 

installed in 1991. 

Meteorology 

Continuous measurements of wind, temperature, 

dewpoint, pressure, and precipitation have been made at 

BRW since 1973. On June 25, 1990, the temperature at 

BRW was measured as 45"F. At the same time the 

temperature at the NWS office in the village of Barrow was 

measured at 71 "F. This was the largest difference ever 

recorded between the two sites since measurements have 

been taken. Measuring equipment was checked at both sites 

to confirm the difference. The most likely cause was a heat 

island effect due to the wind direction and amount of ice still 

on the ocean. Wind was from the east and after passing over 

the relatively cold ice had only 0.8 km to pass over before it 

reached the observatory building and several miles over 

relatively warm land before it reached town. All equipment 

calibrations and maintenance were performed on schedule 

and without any problems of note. 

CAMS 

The Control, Acquisition, and Monitoring System 

(CAMS) was installed in the summer of 1984. It has worked 

with minimal problems since inception. During 1990 the 

only problems noted were during a power outage that caused 

start-up errors when power was restored and a separate 

incident of a bad monitor board. For a time the bad monitor 

board caused the aerosols and solar radiation acquisition box 

to quit several times per day. The board was changed and all 

autorestart problems were fixed. 

Surface Ozone 

Since the source of most of the ozone measured at the 

surface is from the stratosphere, a knowledge of the surface 

distribution can be useful in the study of transport processes 

in the atmosphere. Surface ozone has been measured at 

BRW since 1973 with an ECC. In 1974 a Dasibi 

chemiluminescent ozone analyzer was introduced and run in 

conjunction with the ECC. After a suitable side-by-side 

comparison, the Dasibi became the working station 

instrument and has been in use since then. The BRW 

instrument ran without problems all year. Routine cleaning 

of the optics was performed and weekly calibrations showed 

no problems. 

Dobson 

Dobson observations have been a part of the BRW 

operation since August 1973. With the exception of a break 

from 1983 to 1986, a continuous record of observations 

exists from 1973 to the present. The current instrument is 

Dobson no. 91. Over the years few problems have occurred 

with the Dobson instruments because of the long working 

history and the maintenance expertise that is available from 

personnel in Boulder. During this year, a clock drive motor 

was replaced in Dobson no. 91 in January after the old motor 

quit. Because of winter darkness, routine observations are 

started in February and continue through October. Boulder 

personnel visited the observatory in February to ascertain the 

condition of the instrument. The instrument was found to be 

in good shape. Minor maintenance of the Dobson was done 

during that visit. 

Halocarbons 

The halocarbons flask sampling project was initiated in 

September 1973 and has been carried out successfully since. 

There were no changes in this status during 1990. An 

automated HP-GC system was installed in October 1986 to 

measure N20, CFC-11, CFC-12, CC14, and CH3CC1 3• Since 

start up, the GC program has undergone several upgrades 

and minor modifications; most notable was the addition of a 

Shimadzu GC in 1987, which was optimized to measure 

N20. A column in the HP GC was changed to permit the 

measurement of CFC-113 in addition to the others mentioned 

above. During 1990 the majority of problems were either 

printer related or gas leaks due to the complex nature of the 

plumbing. During 1990 the sampling frequency was 

increased from one sample every hour to once every 0.5 

hour. This has the advantage of greater precision by virtue 

of the larger statistical population used to calculate the 

concentration of the gases and a lower chance of electronic 

drifting between samples. The current sampling regime 

cycles through a calibration, an ambient air sample , a 

10 
calibration, and a second air sample for each species. The 

new system also employs a 2-point calibration for better 

accuracy. 

Methane 

To measure CH4 , an automated GC was installed in 1985. 

The automated GC measurements augmented prior CH4 

measurements obtained from flasks. CH4 flask samples date 

back to 1983. Flasks for both the C02 and CH4 are still 

being collected. Automated CH4 GC samples are taken 

every 12 minutes using the following sampling scheme. 

Calibration gas, ambient air, calibration gas, etc. A 1-point 

calibration is used and very good accuracy is maintained. 

The system operated well all year with the only problem 

coming from the stream selection valve. The valve was 

replaced after it had become worn enough that it would no 

longer align itself with the ports. 

Cooperative Programs 

The cooperative program between CMDL and the USGS 

in Fairbanks has a long history that goes back to 1971-1972. 

For 1.5 years the USGS collected air samples for CMDL for 

a site suitability study. When it was determined that Barrow 

would be a good site, BRW was established and data 

collection began in January 1973. The Barrow Magnetic 

Observatory was started in 1949. In 1957 additional 

buildings were constructed at the present site. In 1975 all 

Barrow Magnetic Observatory functions were consolidated at 

the present site, approximately 0.4 km west the CMDL site 

and CMDL personnel began assisting in the operation. 

Instrumentation in the magnetic observatory includes an 

EDA PPM- 105 proton magnetometer and an EDA FM1 OOBR triaxial fluxgate magnetometer. The site is 

unmanned, and since the establishment of the observatory, 

BRW personnel check the operation once per week and 

report to the USGS as needed. A technician from USGS in 

Fairban.ks performs an on-site inspection and collects data 

every 6 weeks. This cooperation between the two agencies 

has been beneficial over the years and it is expected to 

continue. 

In 1978 the BRW staff assumed responsibility for reading 

and recording data from the University of Wyoming shielded 

rain gage. The gage is part of the Soil Conservation Service 

network of rain gages across the entire state of Alaska. In 

1989 a program was established to study the collection 

efficiency of several types of collectors. BRW was chosen 

as one of the locations for this study because of the rapid 

service ability by CMDL staff members if any problems 

arise. Since then,· the BRW staff have participated in the 

evaluation of five snow collectors. 

A program was started in 1983 in cooperation with 

CSIRO to measure the 13C/12C ratio in ambient air. The 

theory is that the ratio should be decreasing due to the 

increased input of 13C depleted C02 from combustion of 

fossil . fuels. A pair of 5-L glass flasks are collected and 

shipped to Australia each month. Several broken flasks are 

noted throughout the year and steps have been taken to find 

the source of breakage. 

The SIO C02 sampling program was one of the first flask 

sampling programs initiated at BRW in January 1974. 

Weekly samples have been taken since and continue up to 

the present. No problems have been reported and flasks 

were taken on a weekly basis. 

A flask sampling program was initiated in 1983 with the 

University of California, Irvine, to measure CH4• Personnel 

from the university are sent to Alaska each quarter to collect 

whole-air samples. A trip ending in BRW, consists of a 

transect across the state to collect samples. Samples are 

analyzed for CH4 • 

The surface air sampling program started in August 1975. 

It is part of the 80th Meridian Program sponsored by the 

U.S. Naval Research Laboratory. The main objective was to 

study spatial and temporal distribution of radionuclides 

released by nuclear detonations and other nuclear events. 

Personnel also measured 21opb and 7Be. The program at 

BRW consists of a weekly filter sample. The pump is 

checked once per month for proper flow and lubrication 

levels. Personnel from DOE visited the site in July to 

inspect and calibrate the pump and to train the SPO crew. 

The Geophysics Research Laboratory of the University of 

Tokyo began measuring magnetic storm effects in 1985 at 

BRW. An audio-cassette recorder was modified to extend 

the life of a 90-minute audio cassette to 1 week and is used 

as a data Jogger. A series of three sensors were set up 70-m 

from the observatory building and are used to detect 

micro-pulsations of 0.001-5 Hz. In June 1990 the system 

was rewired by University of Tokyo personnel and the 

system was put into a standby mode. 

11 

The isotopic study of wetland and atmospheric CH4 

projects from the University of Washington continued 

through 1990, but there were problems with maintaining 

adequate supplies. BRW staff open 35-L evacuated flasks to 

the air, and samples are collected on a weekly basis. On 

several occasions the flasks were not available and several 

samples were missed. The project measures 13C/12C 

composition in CH4 and was started in 1986. 

The University of Washington also conducted an airplane 

aerosol project during June. In the course of the experiment, 

a TSI CNC was run at the station after it was discovered that 

it could not handle the rapid change in pressure in the 

airplane. There were no problems after it was installed as a 

ground-truth instrument. 

BRW personnel collected whole-air samples for the OGC 

trace gas monitoring program. Using a metal bellows pump, a 

series of three stainless-steel flasks, 800-mL each, are filled with 

air and analyzed for halocarbons, C02, CO, and CH4 at OGC. 

The program ran well all year and samples were collected on a 

weekly basis. This program was initiated in 1980. 

During the winter of 1990, Biospherical Instruments, 

under NSF sponsorship, installed equipment in Barrow at 

UIC/NARL, to measure UV irradiance. The system consists 

of a high-spectral resolution scanning spectroradiometer 

optimized for UV light. BRW is part of the NSF 

spectroradiometer network. BRW personnel calibrate the 

equipment and troubleshoot any problems that arise in the 

hardware. 
The University of Alaska, Fairbanks, maintains a 

chemiluminescent instrument used to measure NO, NOY, 

HN03 , and N03 • The program has been operated in BRW 

in the past on a short-term basis. In February 1990 it was 

installed to run for at least 1 year. The only problem 

connected with the instrument was with the diaphragm 

pump. Several diaphragms showed signs of premature wear 

and subsequent failure. A GC for measuring PAN was also 

set up and was maintained by CMDL personnel for a 

1-month period. 

The Wave Propagation Laboratory in Boulder maintained a 

SODAR system in BRW for collecting inversion layer data. 

The system was augmented in March with a tethered balloon 

thermometer and an upward-looking radar antenna. The 

experiment was conducted, in part, to check out the equipment 

in an arctic environment. The project ended in April. 

As in 1989, ClRES, under funding by the National 

Academy of Sciences, maintained a project to measure 

surface ozone and particulate and gaseous bromine at BRW 

to examine the causes of surface ozone destruction. A 

photochemical experiment was also performed to measure 

particulate bromine formation. 

The University of Rhode Island filter sample was 

discontinued this year. It was started in 1976 and filters 

were collected until 1990. 

The Naval Surface Warfare Center visited BRW to check 

on the viability of using the station as a base for data logging 

equipment used to record fluctuations in the earth's magnetic 

fields. 

2.3. SAMOA OBSERVATORY 

C.J. FARMER 

2.3.1. OPERATIONS 

During 1990 the major event in American Samoa was 

Hurricane Ofa. The hurricane passed near the island 

February 2-4, with the greatest intensity occurring during the 

afternoon of February 3; it was moving relatively slowly at 

5-6 mph during that time. The hurricane had sustained 

winds of 65-75 mph with gusts at the observatory of over 

100 mph. Over 6 inches of rainfall were recorded during this 

period and the minimum pressure at the observatory was 979 

mb (986 mb at sea level). 

Major damage at the observatory consisted of the Joss of 

the walk-up tower at Matatula Point, the two buildings with 

all equipment that was contained in them, and the stair 

railings. There was also some damage to the main 

observatory building shingles and some of the rooftop 

instruments. For the most part, the only sampling program 

that was affected by the damage was the continuous co2 

sampling. To get the program running again, a temporary 

sampling mast was installed at Matatula Point and new lines 

put in place to the bottom of the stairs. This was completed 

by the middle of April and sampling continued with this 

temporary setup until the middle of October. 

The generator failed during the hurricane due to a bad fuel 

transfer pump from the underground tank to the "day" tank. 

It stopped around the peak of the hurricane. The 

photovoltaic system did keep the meteorological and solar 

instruments running throughout the hurricane passage. 

The major work to repair the Hurricane Ofa damage began 

in June. A new Matatula Point building was constructed 

using concrete blocks with a concrete roof. This is expected 

to be a more permanent building if another hurricane passes 

near the area. Repairs were then made to the stairs with 

many of the support posts and planks and all the railings 

being replaced. The carport and main building were then 

reshingled and after a delay to wait for wood to arrive, a new 

roof cap was put in place. Later in the year this new wood 

began to warp badly and it was brought to the attention of 

the contractor. A solution had not been worked out by the 

end of the year. After all the other work was completed, the 

outside of the observatory building and the surrounding 

concrete were repainted. There were also some repairs 

necessary on the houses due to the damage done by the 

hurricane. The roofs both needed to be reshingled and the 

garages needed repair. This work was not completed by the 

end of the year. Other work on the houses included 

remodeling of the kitchen in T-7 and preparation of the 

house T-11 for new personnel. The carpets were steamcleaned, a new stove was purchased for the house, and some 

small repairs were performed. Other repairs were made once 

the new person arrived. Estimates were also obtained for a 

couple of larger jobs that needed to be done. 

The diesel tank for the generator was tested for leaks in 

November. This was part of an island-wide testing program 

to check all underground storage tanks instituted as a result 

of action by the Environmental Protection Agency. The tank 

showed no leaks. Testing of this nature will have to be done 

on a bi-annual basis to conform with the new regulations. 

A new computer was purchased for the observatory. The 

new unit is a Compaq 386S and should provide us with 

enough computing power for several years. 

The observatory was broken into during the year on at 

least one occasion. The major item taken was a camera 

belonging to the Station Chief that was being used to take 

pictures of the repair work at the observatory. 

The government pickup was involved in an accident in 

early October. It went off the road and flipped upside down 

in shallow water. There was no serious injury, but the 

vehicle was a total loss. A replacement vehicle (1986 Dodge 

pickup) arrived by the end of November. 

There was a staff change at the observatory during the 

year. The electronics technician was replaced by an 

electrical engineer. There was temporary help by the 

electronics technician from MLO to fill the gap between the 

technician's departure and the engineer's arrival. 

2.3.2. PROGRAMS 

12 

Table 2.4 summarizes the programs at the observatory for 

1990. Further discussion of some of the programs follows. 
TABLE 2.4. Summary of Measurement Programs at SMO in 1990 

Program 

Surface 0 3 

Total 0 3 

0 3 profiles 

CFC-I I, CFC-12, N20 

CFC-I I, CFC-12, NzO. ca,. 

CH3CC13 

N20 

Aerosols 

Condensation nuclei 

Optical properties 

Solar Radiation 

Global irradiance 

Direct irradiance 

Turbidity 

Meteorology 

Air temperature 

Dewpoint temperature 

Pressure 

Wind (speed and direction) 

Precipitation 

Precipitation Chemistry 

pH 

Conductivity 

Cooperative Programs 

C02, 13C, N20 (SIO) 

GAGE project: CFC-11, CFC-12, 

Np, CH3CC13 , CC14 (SIO) 

Various trace gases (OGC) 

Wet-dry deposition (NADP) 

Bulk deposition (EML) 

Hi-vol sampler (EML) 

Hi-vol sampler (SEASPAN Project) 

C02, CH4, trace gases (NCAR) 

13CJ'2C ratio (Univ. of Wash.) 

Light hydrocarbons (UCI) 

Instrument 

URAS-2T IR analyzer 

3-L glass flasks 

0.5-L glass flasks, through analyzer 

0.5-L glass flasks, P3 pump unit 

Dasibi ozone meter 

Dobson spectrophotometer no. 42 

Balloonborne ECC sonde 

300-mL stainless steel flasks 

HP5890 automated GC 

Shimadzu automated GC 

Pollak CNC 

G.E. CNC 

Four-wavelength nephelometer 

Eppley pyranometers with Q and RG8 filters 

Eppley pyranometers with Q filters on tilted mounts 

Eppley pyrheliometer with Q filter 

Eppley pyrheliometer with Q, OGI, 

RG2, and RG8 filters 

Sunphotometers with 380-, 500-, 778-, 

and 862-nm narrowband filters 

Thermistors (2) 

Max.-min. thermometers 

Polished mirror 

Capacitance transducer 

Mercurial barometer 

Bendix Aerovane 

Rain gauge, weighing bucket 

Rain gauge, tipping bucket 

Rain gauge, plastic bulk 

Aerochem wet/dry collector 

Fisher model 805 meter 

Beckman model RC-16C meter 

5-L evacuated glass flasks 

HP5880 gas chromatograph 

Stainless steel flasks 

HASL Chemetrics wet-dry collector 

Plastic bucket 

High-volume sampler 

High-volume sampler 

Evacuated stainless steel flasks 

30-L pressurized cylinder 

1-L evacuated stainless steel flasks 

13 

Sampling Frequency 

Continuous 

l pair wk·t 

l pair wk· 1 

l pair wk·t 

Continuous 

4 day·t 

2mo·t 

I pair wk·t 

I sample (2 h)·l 

I sample (2 h)· 1 

l day-1 

Continuous 

Continuous 

Continuous 

Continuous 

Continuous 

Discrete 

Discrete 

Continuous 

l day· 1 

Continuous 

Continuous 

l wk· 1 

Continuous 

Continuous 

Continuous 

l day·1 

l day·1 

l day- 1 (CMDL); 

l wk· 1 (NADP) 

l day· 1 (CMDL); 

l wk·1 (NADP) 

3 flasks wk·1 

l h"1 

3 flasks wk·1 

(3 flasks set·1) 

l wk· 1, wet; 

discrete, dry 

Continuous (l bucket mo·1) 

Continuous (l filter wk-I) 

Continuous (l filter wk·!) 

l pair wk·1 

2mo· 1 

3-4 flasks qtr· 1 
Carbon Dioxide 

The continuous measurements were most affected by the 

hurricane. TI1e loss of the tower at Matatula Point and the 

buildings to house the water removal system resulted in these 

measurements being discontinued until the middle of April. 

The installation of new sampling lines to the Point had been 

completed prior to the hurricane and testing the new lines 

against the old lines was underway. A temporary sampling 

mast and a small building were erected at the Point in April 

so that continuous measurements could be restarted. The 

measurements from this temporary mast were in agreement 

with those just before the hurricane. This setup ran until 

October. The problem with the cracked pump heads on the 

C02 air pumps continued. 

In October a new sampling mast was installed and the 

moisture removal system for the co2 sampling line was 

moved into the new building at the Point. The sampling 

mast is now a 13-m tall aluminum mast. New C02 sampling 

lines were installed from the mast to the bottom of the stairs 

at this time as well. The air cadet pumps were moved from 

the main building to the Point building in an attempt to cure 

the problem of the cracked heads. This has taken care of the 

problem. 

During this same time period, a new Siemens continuous 

analyzer was installed in the main building to monitor C02. 

A new flask sampling unit was put into use in October. 

The so-called MAKS unit is used to fill the 0.5 -L flasks and 

is designed to also accept 3-L flasks with two sampling ports 

when they become available. A problem with water vapor 

content of the air caused a significant disagreement between 

the flask pairs at first. This was solved by reducing the 

pressure to which the flasks were filled. 

Surface Ozone 

Observations continued during 1990 with no significant 

problems or downtime. Occasional loss of data occurred 

when the CAMS unit failed to recognize the signal from the 

Dasi bi. 

Total Ozone 

Observations were conducted throughout the year without 

difficulty. The measurements were changed for awhile 

during August through October to a CDADC sequence 

instead of the normal ADADA sequence. 

Ozone Profiles 

In January two launches were made before the ozonesonde 

program was discontinued due in part to the hurricane, but 

also lack of funding. 

Nitrous Oxide and Halocarbons 

The GC operated during the year with only a few 

problems. There was a continuation of the problem with the 

Shimadzu' GC not coming up on line after a power failure. 

The stream select valve failed in November and caused some 

loss of data. The most puzzling problem was the presence of 

a contamination peak on channel B that was affecting the 

methyl chloroform peak on one of the calibration standards. 

In late October a new operating program was installed. 

This program provides the capability of plotting out the data 

from the previous 30 days for any of the gases sampled. 

This has not only increased the interest of the observatory 

personnel in the results, but could also prove to be an 

important diagnostic tool. 

A new printer was also installed during the year. This has 

cured the problems with the paper jams that seemed to be 

occurring quite often. The paper handling system was also 

arranged so that an entire box of paper can be put into 

service at a time. This not only decreases the chance of 

running out of paper, but also saves a great deal also. 

Flask sampling continued on a weekly basis when flasks 

were available. LEAPS flasks were substituted for the 300-

mL flasks once per month when available. 

Aerosols 

The G.E. CNC had problems with a high background after 

it was greased in July. It was taken apart and boiled out and 

the problem was taken care of. The only other problem was 

condensation accumulating in fairly large amounts in the 

inlet line. The line was shortened as much as possible and 

any sags were removed and later insulation was added to 

cure the problem. There were no significant problems with 

the nephelometer during the year. All calibrations were 

performed as necessary. 

Solar Radiation 

14 

The pyrheliometer suffered from tracking problems during 

part of the year. Realignment and leveling in September 

alleviated most of this problem. A bad cable on the tracking 

NIP went undetected for a couple weeks in December 

causing some loss of data for this instrument. The RG8 

pyranometer was swapped out during the year. The filterwheel NIP was compared with the standard NIP during June. 

The sun photometers began having problems during the latter 

part of the year, but apparently the program had been 

discontinued and no replacements were sent to the 

observatory. 

Meteorology 

The meteorology program had no significant changes 

during the year. The cable running from the observatory to 

the Aerovane was replaced in July and August. Wind data 

was lost for about a month as a result of this problem. A 

new Aerovane was installed shortly before this problem had 

occurred. Instrumentation ran well during the hurricane with 

the wind record being pegged (100 mph) on at least two 

occasions. The temperature board on the dewpoint 

hygrometer went bad resulting in bad air temperature 

readings with this instrument, however the dewpoint 

measurements continued in agreement with sling 

psychrometer measurements (within 1 'C). 

Precipitation Chemistry 

Daily precipitation samples continued to be analyzed for 

pH and conductivity during the year. These samples were 

then sent to MLO for further analyses. SMO began 
analyzing some of the samples at the observatory for several 

different ions. No major problems with the wet/dry collector 

occurred during the year. 

Cooperative Programs 

There were no changes in cooperative programs at the 

observatory during the year. The most significant 

involvement during the year was the participation in the 

NASA Globe Program through the SEASPAN project of the 

University of Miami. During the months of May and June 

daily filter changes were made to provide ground 

measurement support for the program. The operation of the 

GAGE gas chromatograph was taken over by SIO. This 

system was down for almost the entire year, due first to the 

loss of a calibration tank and then to the change of principal 

investigators on the project. The observatory also provided 

support for the Combined Release and Radiation Effects 

Satellite Program. The University of Alaska, Fairbanks, 

conducted measurements on two evenings at the observatory 

studying the ionization of gases released from a satellite 

passing overhead using a low-light camera. 

A new measurement program was begun in early May that 

includes sampling for formic, acetic, and nitric acids, and 

sulfur dioxide. It utilizes a condensation sampling technique 

and analysis by ion chromatography. The results are to be 

compared with other measurements performed on the marine 

boundary layer during the past several years and will also be 

used to study direct emission of the organic acids from 

vegetation. The long-term measurements of the nitric acid 

and sulfur dioxide wiil be used to detect local efft:cts from 

the nearby villages well as long-range transport into the 

area. 

2.4. SOUTH POLE OBSERVATORY 

C. GROENEVELD 

2.4 .1. OPERA TIO NS 

The normal schedule of deployment of personnel to SPO 

does not conform to the calendar year, instead it covers the 

period from about November 1, 1989, to November 1, 1990, 

and consequently this report will review this period of 

operations. 

SPO staffing for the winter totaled 20 people, 6 scientists, 

and 14 support personnel hired by the NSF contractor. 

During the summer, the station population varied from 40 to 

100 people. 

The CMDL 1989-1990 SPO staff arrived at the South Pole 

on November 1, 1989. CMDL Boulder personnel spent 

November and December at the SPO to assist in the station 

turnover helping in operations and maintenance tasks, as 

well as to upgrade the NOAH GC's. 

In the spirit of South Pole cooperation, help from other 

winter-over scientific and technical personnel was obtained 

for CMDL operations when needed. CMDL's balloon 

program was expanded to include a cooperative effort with 

the University of Wyoming. 

The SPO operation is located in the Clean Air Facility 

(CAF) upwind of the main Amundsen-Scott South Pole 

Station. The CAF is a wood frame building, 5 m x 10 m, 

with the long axis of the building lined up approximately 

grid north and south (the Greenwich Meridian is grid north at 

the South Pole). CMDL's operations are part of NSF's total 

science complement that uses the CAF. The CMDL 

programs occupy about one third of the building, while the 

remaining two thirds of the CAF are occupied by summer 

science programs that have NSF grants, CMDL cooperative 

projects, several NSF winter-science projects, and a joint 

CMDL and CAF electronics shop. 

The CAF was built and suspended above the snow surface 

on steel "H" beams to prevent it from being drifted over and 

to keep the air sampling stacks above the blowing surface 

snow. Built in 1977, the CAF was raised once in 1987 and 

the base of the building is presently about 2 m above the 

snow surface. 

Two major projects were planned for the CAF during the 

1990 austral summer: removal and replacement of the 

fiberglass insulation in the roof with blue board and a 

complete rewiring of the CAF electric distribution. Both 

projects were put on hold due to delays in other SPO 

projects. These other projects included the raising and 

repairing of the dome over the main station and the 

replacement of the powerplant generators. The dome project 

that included the removal of a large snow drift that had 

formed downwind of it was completed as planned. However, 

only one generator was replaced which caused some minor 

power conservation inconveniences during the year. 

The problem of summer overheating inside the CAF was 

solved by reducing passive solar heating inside of the 

building by covering the windows in the main room with 

silvered opaque plastic. The window coverings and an 

upgrading of the exhaust fan in the main instrument room 

wall helped to reduce the disruptive CAF temperature 

variations that have been experienced in other years. The 

building still experiences cold inside temperatures in the 

winter, but this cooling impacts human habitation more than 

it interferes with operating equipment. In winter the inside 

building temperature varies from about 65.F to 45•p and is a 

function of the wind direction and speed and the outside 

ambient air temperature. The silvered opaque plastic was 

removed at sunrise to allow the new crew to install reflective 

film. 

Data transmission was improved this year due to the 

installation of a Novell Network line from the COMMS 

office to the CAF and the addition of LES-9 satellite 

transmissions from SPO to the continental United States. 

Message traffic is relayed via satellite from SPO to 

Florida and then by telephone line transmission to Boulder. 

An alternate route that is sometimes used goes by HF radio 

to McMurdo and then via satellite to Malabar, Florida. The 

ASA Communications Coordinator is the first contact in this 

process, transmitting all outgoing traffic and receiving and 

sorting all incoming messages. Messages are handled as 

either data or text and all traffic to or from SPO is accessible 

to NSF, ASA, CMDL, and the other PI's. 

15 
Data transmission can be limited in the summer when the 

summer increase in science projects results in an increase of 

data transmission to the continental United States; however, 

no limit was imposed on the science projects during the 

winter. The communications coordinator was able to send 

out as much traffic as satellite time and weather conditions 

would allow during the winter. There were occasional 

delays of a day or two but all data would eventually get sent 

out. Blowing snow can create enough static charge on the 

outdoor ground antennas that there were periods when 

receiving or transmitting messages were not possible at SPO. 

Typical message traffic for CMDL included monthly 

CAMS data, NOAH GC data every 5 days, BSI UV data 

daily, and general text messages to Boulder. The entire suite 

of CMDL projects continued and remained in operation 

throughout the year. They are listed in Table 2.5. A 

summary of the major upgrades for each project follows: 

2.4.1. PROGRAMS 

Aerosols 

The CMDL operator makes two sets of three discrete 

observations each day with the Pollak CNC. The Pollak 

observations are used to calibrate the G.E. CNC and the TSI 

CNC. The microamperes meter was replaced at opening and 

then the lamp power supply was rebuilt in November. After 

that, the Pollak operated normally. 

The TSI CNC makes continuous aerosol measurements 

and was installed during the summer of 1989 to replace the 

G.E. CNC. When the supply of butyl alcohol ran out several 

months before station opening, the TSI was turned off and 

remained on inactive status until station opening when more 

butyl could be brought in. After receiving the butyl alcohol, 

the TSI was back on line by November 22 and ran problem 

free for the rest of the year. 

The G.E. CNC has been the primary instrument used to 

make continuous aerosol measurements at SPO since 1975. 

Both G.E.s on station were rebuilt during the summer and 

continued operation until about March when one G.E. began 

to drift from calibration to calibration. The valve seized on 

one instrument and the spare G.E. would not settle out or 

stabilize from one calibration to another. The intercomparison with the TSI was terminated in August, after 

adequate overlap data with the TSI was obtained. The G.E. 

counters were retrograded back to Boulder on opening in 

November 1990 and continuous CNC measurements will 

now be obtained with the TSI counter. 

The optical properties of submicron aerosols are 

determined with the nephelometer by measuring the 

difference in light scattering between a control air sample 

and the ambient air sample. The nephelometer ran trouble 

free all year. A C02 calibration was performed in April. In 

September the four channels began to stair step on the chart 

recorder, but normal operations were achieved by checking 

and refurbishing all the control boards in the instrument. 

The aethalometer measures the carbon content of 

submicron aerosols by measuring light absorption on 

aerosols collected on a filter substrate. The aethalometer ran 

without problems for most of the year. In July the light 

source became intermittent for about 2 weeks but normal 

operations were achieved by reseating and aligning the light 

source on top of the filter chamber. This problem occurred 

once more before station opening and was solved by the 

same method. 

CAMS 

The CAMS has been collecting data at SPO since 1984. It 

uses 250 Kbyte DEC tapes to record data. No records of 

CAMS BRAM lost or autorestarts were kept. Most 

autorestarts were the result of keypad lock-ups due to 

improper or too rapid entries. The rest were due to 

temporary power losses by either routine maintenance or 

occasional malfunctions in the SPO power plant. The C02 

CAMS lost a BRAM board on August 1, probably due to a 

static discharge. The BRAM board was replaced and normal 

operations resumed by August 8. 

Carbon Dioxide 

The C02 program consists of a continuous infrared 

analyzer that makes in situ measurements and a flask 

sampling program that augments and provides for 

independent checks on the continuous sampling program. 

Both programs began in 1975. New station gas standards 

were installed and instrument calibrations were run in early 

January. In late January the continuous analyzer's relay 

board malfunctioned and the C02 standard gas and air lines 

would not switch through its normal cycle. A spare board 

was located, installed, and normal continuous analyzer 

operations resumed. The air sampling pump diaphragm was 

replaced in May and once again in June. During the May 

diaphragm replacement, the pump lines were inadvertently 

reversed. This reversal of lines occurred on May 19 and was 

not discovered and fixed until May 20. Working gases were 

replaced in May and again in October. 

Meteorology 

The standard meteorology measurements of wind 

direction and speed, 2-m and 20-m temperature, 2-m 

humidity, and station pressure continued as in years past. 

The more complicated hygrothermometer was removed from 

the roof of CAF and installed at 2-m AGL on the 

meteorological tower in December. After the tower 

installation, the instrument was checked out and calibrated. 

During the winter the air intake orifice of the 

hygrothermometer would become packed with snow and 

frost, especially during humid or windy conditions at which 

time such accumulations in the line would occur more often. 

This accumulation of snow and ice increased the 

maintenance required for the hygrothermometer 

significantly. 

16 

The T. and Tb winter calibration was conducted during 

March 10-April 13. The length of comparison was mainly 

due to inexperience and difficulty with communication to 

and from Boulder in trying to resolve procedural problems. 

The calibration was eventually completed and resolved at the 

South Pole but 1 month of T. - Tb data were lost. 
TABLE 2.5. Summary of Measurement Programs at SPO in 1990 

Gases 

C02 

C02,CH4 

Program 

Surface 0 3 

Total 0 3 

Ozone profiles 

CFC-11, CFC-12, NzO, CH3C03. cc~ 

CFC-11, CFC-12, N20 

Aerosols 

Condensation nuclei 

Optical properties 

Carbon aerosols 

Solar and Terrestrial Radiation 

Global irracliance 

Direct irracliance 

Turbidity 

Albedo 

Meteorology 

Air temperature 

Pressure 

Wind (speed and direction) 

Frost-point temperature 

Cooperative Programs 

C02, 13C, N20 (SIO) 

Total surface particulates (DOE) 

Various trace gases (OGC) 14C (NOAA/ARL} 

Snow aciditiy (NOAA/ARL) 

lnterhcmispheric 1Jc/14C (CSIRO) 

Ultraviolet radiation (NSF) 

Polar stratospheric clouds (Univ. of Rome) 

Insuument 

URAS-2T IR analyzer 

0.5-L glass flasks, through analyzer 

0-5L glass flasks, p3 pump unit 

Dasibi ozone meter 

Dobson spectrophotometer no. 80 and no. 82 

Balloonbome ECC sonde 

Shirnadzu automated mini-2 gas chromatographs 

300-mL stainless steel flasks 

300-rnL stainless steel flasks 

PollackCNC 

G.E.CNC 

TSICNC 

Four-wavelength nephelometer 

Aethalometer 

Eppley pyranomters with Q and RG8 filters 

Eppley pyrheliometer with Q, OG 1, RG2, 

and RG8 filters 

Sunphotometers with 380-, 500-, n8-, 

and 862-nm narrowband filters 

Eppley pyranometers with Q and RG8 

filters, downward facing 

Platinum resistor, 2- and 20-m heights 

Capacitance transducer 

Mercurial barometer 

Bendix Acrovane 

Hygrometer 

5-L evacuated glass flasks 

High-volume sampler 

S1ainless-s1cel flasks 

1,500 and 3 ,000 psi spheres 

125-mL Nalgene flasks 

5-L glass flasks 

UV radiome1er, da!a logger 

Optical lidar 

Sampling Frequency 

Continuous 

1 pair twice mo-I 

1 pair twice mo-I 

Continuous 

3 day-I 

1 wk-1, summer, autumn, winter; 

1 (3 day)-1, spring 

l sample (3 h)"l 

I pair wk-1, summer 

3 wk-1, summer 

1 day·1 

Continuous 

Continuous 

Continuous 

Continuous 

Continuous, summer 

Discrete, summer 

Discrete, summer 

Continuous, summer 

Continuous 

Continuous 

2 times wk·1 

Continuous 

Continuous 

2 mo·1 (3 flasks sampJe-1) 

Continuous 

( 4 filters mo· 1) 

Twice mo·1 (3 flasks set·!) 

250 or 500 psi day·1 

1 (2wk)"1 

1 or 2 flasks mo·I 

Periodic 

Instrument inoperative 

A nagging and persistent problem with the take-up reel on 

the wind recorder caus~ the paper to jam in the recorder. The 

problem was traced to the aluminum gears on the take-up reel. 

The problem was solved by shifting the drive gear over about 1 

mm and filing the burrs off the take-up reel. 

Flask sampling measurements for N20, CFC-12, and CFC-11 

began in 1977. 

Both GC's were upgraded and replumbed in January. 

Argon-methane carrier gas was added to GCl at that time. Both 

GCs ran all year without a mole sieve change. Gel experienced 

a steady decrease in peak height throughout the year, possibly 

caused in part by a sensitivity loss because the mole sieve was 

not changed. By September, the F12 peak on GCl was below 

the threshold set for recording the peaks to the PC; this in turn 

caused the data integrator to revert to a default mode and stop 

recording data. The F12 peak, however, was still showing up on 

Halocarbons 

Two Shimadzu automated mini-2 GCs analyze ambient 

samples twice each hour and a summer flask sampling program 

collects ambient air sample pairs once per week. 

The GC in situ sampling of N20, CFC-12, and CFC-11 began 

in 1983, and CH3CC13 and CC14 were added at a later date. 

17 
the GC chart recorder. When this was discovered and rectified 

on September 27, data was once again recorded on the PC by 

lowering the threshold value on Integrator 1. 

Solar Terrestrial Radiation 

This surface-based program measures several components 

of the solar and terrestrial r adiation budget at the snow 

surface using Eppley pyranometers and pyrgeometers that 

measure global and albedo radiation, pyrheliometers for 

direct solar radiation, and I-series sunphotometers for 

turbidity . Solar radiation measurements have been made 

since 1976. 

The solar radiation rack inside the CAF was upgraded and 

rewired in early December. During this period all 

experiments were off line. 

An experiment was conducted to determine the 

effectiveness of snow and frost removal by aspiration on 

Eppley pyranometer RG8 domes in the summer and quartz 

domes in the winter. While the aspiration works, it does not 

always keep the domes free of frost buildup especially when 

temperature, humidity, and cloud cover conditions combine 

to create persistent frost buildup on the domes. 

Ozonesondes 

The balloon sonde program that was started in 1986 to 

investigate the destruction of stratospheric ozone over SPO, 

continued throughout the year with 50 successful flights. 

ECC ozonesondes were used with a VIZ radiosonde and a 

GMD radiotheodolite receiving system to make each 

sounding. The GMD tracking system is used jointly with the 

South Pole Meteorology Office. Flights were occasionally 

postponed due to high winds. 

Surface Ozone 

Surface ozone measurements have been made at SPO 

since 1975 and have provided an uninterrupted data set of 

tropospheric ozone in one of the cleanest places on earth. 

Dasibi 1328 was replaced by a 5000 series instrument (the 

most up-to-date version of Dasibi ozone measurement 

instruments) in January and normal SPO operations 

continued throughout the year. The Dasibi-CAMS interface 

problem continued intermittently throughout the year. 

Total Ozone 

Dobson total ozone measurements at SPO were started in 

November 1961 and have continued to the present. Dobson 

instrument no. 82 was repl aced by no. 80 in December 1989. 

Dobson no. 82 was returned to Boulder for calibration and 

refurbishment. During shipment to SPO, Dobson no. 80 was 

inadvertently handled as regular cargo and left outside at 

subfreezing temperatures. The freezing of the instrument 

contributed to some initial calibration problems. To remedy 

this, two calibrations per month were conducted until 

October 1990 to monitor the situation. At that time it was 

determined that Dobson no. 80 had completely stabilized. 

Frostpoint Sondes 

This year a new frostpoint sounding program was initiated 

at SPO to obtain preliminary measurements of stratospheric 

water vapor. Most of the equipment for the frostpointbackscatter project didn't arrive until the middle of January 

and then due to end of season activities, didn't get 

inventoried until late February. The telemetry didn't become 

operational until April and instrument preparation took much 

longer than anticipated. The biggest setback to this program 

was the final requirement to inflate the balloons outside 

because no sheltered area opening was large enough to exit 

with a fully inflated balloon. Because of this, we could only 

fill and release balloons when wind speeds were less than 10 

kts from the northeast or less than 7 kts when winds were 

from the east. Ten soundings were planned for the year, but 

due to the initial equipment delays and weather problems 

only seven flights were completed. 

Cooperative Programs 

The CMDL program conducted eight cooperative research 

programs with other independent Pls during the year (fable 

2.5). These programs are carried out with NSF approval and 

provide a way for CMDL and NSF to participate in 

additional research projects that are closely related to the 

CMDL and NSF missions with minimum cost and logistical 

support. These research projects have their own funding and 

principal investigators, and the CMDL program usually 

provides manpower for their operation, maintenance, and 

data collection. 

SCRIPPS-C02 Flask Sampling. No problems occurred 

this year. This program continued the long-term monitoring 

of C02 , 13C/12C ratio, and N20. 

OGC Flask Sampling. No problems occurred this year. 

This program continued to determine the seasonal cycles and 

annual trends in CH4• CO, CH3Cl, CH3I, CH3Br, F-113, 

CH3CC13, C2Cl

4, F-22, SF6, F-11, F-12, F-114, N2

0, and 

other trace species. 

ARL 14C Atmospheric Monitoring. No problems. 1500 PSI 

spheres were used through September and then the 3000 PSI 

spheres were used for the rest of the year. This program 

continues to monitor 14C in the atmosphere as part of a 

world-wide network to monitor debris from nuclear explosions. 

CS/RO Flask Sampling. No problems. This program 

obtains values of the ratio of 13C/12C in atmospheric C02 • 

This information is used in the constraints of a 2-D global 

carbon cycle model which will determine the magnitudes of 

the different carbon sources in atmospheric C02 that are 

involved in the fluxes in the global carbon cycle. 

18 

NZARP Remote Atmospheric Sampling. This experiment 

was discontinued and removed from clean air in early 

December. 

CMDL Snow Samples (MW). Two samples per month 

were collected during the summer months and one sample 

per month was collected during the winter months. Several 
samples were removed by station personnel from their usual 

storage place and were subsequently misplaced. These 

samples were never found. 

DOE Atmospheric Aerosol Sampling-Filter Samples. No 

problems. The primary objective of this program was to 

study the spatial and temporal distribution of specific natural 

and man-made radionuclides in the surface air. 

Backscattersondes. This experiment incurred many of the 

same problems encountered with the frostpoint project. Four 

of the instruments were found to be inoperative after the 

initial set up. The purpose of this program is to understand 

the formation of polar stratospheric clouds in the Antarctic 

and their role in ozone destruction. 

2.5. REFERENCES 

Bodhaine, B.A., and R.M. Rosson (Eds.), Geophysical Monitoring 

for Climatic Change, No. 16: Summary Report 1987, 110 pp., 

NOAA Air Resources Laboratory, Boulder, CO , 1988. 

Elkins, J.W., and R.M. Rosson (Eds.), Geophysical Monitoring for 

Climatic Change, No. 17: Summary Report 1988, 142 pp., 

NOAA Air Resources Laboratory, Boulder, CO, 1989. 

Komhyr, W.D., and R.M. Rosson (Eds.), Climate Monitoring and 

Diagnostics Laboratory, No. 18: Summary Report 1989, 141 pp., 

NOAA Environmental Laboratories, Boulder, CO, 1990. 

Thoning, K.W., P.P. Tans, and W.D. Komhyr, Atmospheric 

carbon dioxide at Mauna Loa Observatory, 2, Analysis of the 

NOAA GMCC Data, 1974-1985, J. Geophys. Rts., 94(D6), 

8549-8565, 1989. 

19 
3. Atmospheric Radiation Monitoring Group 

J. J. DELUISI (Editor), E.G. DUTTON, F. KREINER, D.W. NELSON, AND R. STONE 

3 .1 . CONTINUING PROGRAMS 

3.1.1 SURFACE RADIATION 

Surface radiation budget, atmospheric transm1ss1on, and 

aerosol remote sensing measurement projects at the four 

CMDL observatories continued through the year with no 

significant modifications in the measurement systems until 

year's end when sunphotometer measurements were 

discontinued at all sites but MLO. Table 3.1 shows the 

current baseline observatory measurement projects being 

overseen by the ARM Group. Other ongoing projects 

maintained are the surface radiation budget measurements 

made at the top and at the base of the 300 m BAO tower near 

Erie, Colorado, and down-welling broadband solar and 

thermal irradiance measurements at Kwajalein and Bermuda. 

Results of these and other ARM measurement projects 

during past and preceding years have been used in studies of 

surface radiation budget characteristics, light-sensitive 

atmospheric chemical reactions, satellite algorithm verification, climatic impact of volcanic eruptions, climatic trends 

and variability, errors in ozone remote sensing, surface 

optical properties, cloud optical properties, radiative transfer 

calculation verification, instrument development and 

improvement, and solar energy assessment and utilization. A 

summary of significant results from the ARM baseline 

radiation projects follows. 

A dramatic trend in solar irradiance in the late summer at 

SPO was detected in the 14-year CMDL global pyranometer 

record and was shown to be caused by a related trend in 

cloudiness, Dutton et. al. [1 991). The annual forcing of 

diurnal cycles in the near-surface radiation budget as 

measured at BAO are discussed in Dutton [1990]. Surface 

radiation measurements made at the BAO site were used to 

verify satellite determinations of the surface radiation budget 

as discussed by Cess et. al. [1991) . The BRW surface solar 

albedo record was used by Dutton and Endres [1991) to 

better define the data of spring snow melt in the Alaskan 

arctic and improve knowledge of possible related climatic 

trends. 

Kwajalein, Bermuda, and BAO as well as BRW and SPO, 

are candidate sites for participation in the WMO World 

Climate Research Program's Baseline Surface Radiation 

Network (BSRN). The BSRN will consist of approximately 

20 sites globally with participation from several nations. The 

purpose of the BSRN is similar to CMDL's surface radiation 

project, but with emphasis on satellite validation as well as 

better resq.Jution of regional and global variability. 

Beginning in 1989 a different procedure for assuring the 

long-term calibration stability of the solar radiation sensors 

was implemented for the four CMDL sites. The new 

procedure involves swapping instruments once every 2 years 

with an instrument recently calibrated at the Boulder Solar 

TABLE 3.1. Current Radiation Measurements 

at CMDL Observatories 

SWD SWU LWD LWU RG8D DIRQ FWNlP SPIITM MISC 

BRW x x x x x x x x 0 

MLO x 0 0 0 x x x x x 

SMO x 0 0 0 x x x x 0 

SPO x x x x x x x x x 

X, measurements made; 0, measurements not made; SWD, shortwave 

downward solar irradiance; SWU, shortwave upward (reflected) solar; 

LWD, longwave downward (sky emined); LWU, longwave upward 

(eanh emitted); RGSD, downward solar (RGS filter, 0.7 to 3.0 μm) 

irradiance; DIRQ, direct solar; FWNIP, filter wheel normal incidence 

pyrheliometer (discrete observations, four solar bands); SPHTM, 

multiwavelength sunphotometer; MISC, miscellaneous-MLO: global 

diffuse solar, downward solar (OG 1 filter, 0.53 to 3.0 μm), 2-channel 

sunphotometer (water vapor), 3-channel sunphotometer (calibration 

standard); SPO: RGS albedo, direct sun (RGS filter). 

Radiation Facility. This procedure replaces the system 

where the instruments' calibrations were monitored on site 

by a traveling standard. Some on-site visits by traveling 

standards will continue as a secondary check on the 

instruments' calibration. 

Observatory Activities 

An Eppley computer-controlled tracker was sent to BRW 

to replace the aging LiCor tracker. The BRW installation 

is the harshest environment in which these new computercontrolled trackers have been field tested. Also at BRW. 

the pyrgeometers now operate without temperature 

compensating batteries. The battery circuit data were only 

used for real-time monitoring, but tended to interfere with 

other signals. Air ventilating systems are scheduled to be 

added to the upward facing pyrgeometer to reduce solar 

heating errors and prevent ice accumulation on the dome. 

Pyrgeometer no. 27407 went online October 1, 1990, 

replacing the upfacing instrument, no. 23896. 

20 

After nearly two decades of field service, the MLO 

tracking pyrheliome ter no. 2119 began to show serious 

signs of sensitivity loss and was replaced on April 4, 1990, 

by NIP no. 16657. 

SMO continues to be a severe testing site for radiation 

instrumentation where weather-tight instruments absorb 

moisture, spectral filter material provides a culture for 

apparent fungus and bacterial decay, and calibration 

constants drift three to four times faster than normal. 

However, the program is maintained with relatively frequent 

instrument exchanges and calibration corrections. The SMO 

pyrheliometer was swapped in April with instrument no. 

16229 replacing no. 11947. 
The new SPO albedo rack served well during its 2 years 

of operation. The rack was designed to keep the downfacing 

instruments 2.0-2.5 m above the surface, but must be rotated 

onto the upfacing position on occasion for cross comparison 

with other sensors. Instrument icing, particularly on the 

upfacing pyrgeometers, is attended to on a nearly daily basis 

by the observer; but, ice still accumulates on the instrument 

to the extent that some data is lost. Beginning in December 

1990 dome ventilation, similar to that used on the PSPs, was 

added to the upfacing pyrgeometer and helps greatly in 

keeping the ice off the dome. The effect of adding the 

blower to the pyrgeometer was thoroughly tested and no 

resulting additional error was detected. Data that are 

determined to be contaminated by icing are edited from the 

data base during post processing. 

Example Results 

Examination of the year-to-year variation of monthly mean 

global solar irradiance at SPO has revealed large significant 

trends for the months of February and March. The irradiance 

during these months has decreased between 1976 and 1988; 

however, the most recent data indicated that this trend is 

currently subsiding. Figure 3.1 shows the SPO solar irradiance- trends for each month. The decrease in solar 

410 JAN 230 

• • 

irradiance is attributed to increased cloudiness and is discussed 

further by Dutton et al. [1991). 

The long-term atmospheric transmission record from MLO is 

shown in Figure 3.2. The transmission is calculated after the 

technique introduced by Ellis and Pueschel [1971). The earliest 

data in the record suggested that a biennial cycle in the 

transmission may exist. The possibility of the presence of such 

an obvious signal was masked by numerous volcanic eruptions 

after 1963. However, complex demodulation of the record and 

subsequent coherency analysis revealed a high level of 

coherency between a quasi-biennial cycle, the transmission 

record, and the well-known QBO in the equatorial stratospheric 

zonal wind field. Figure 3.3 shows a plot of the coherency 

between the amplitude of the transmission annual cycle and the 

QBO. This result is further discussed by Dutton [1991). 

Surface solar albedo data collected at BRW have been used 

to help establish the long-term date of spring snow melt. Earlier 

work of Foster [1989] suggested that significant trend was 

present in the date of snow melt near BRW. The CMDL albedo 

record provided evidence to the contrary as discussed by Dutton 

and Endres [1991). 

As of press time for this publication, the optical and 

radiation budget effects of the 1991 eruption of Mt. Pinatubo 

are being assessed in the radiation data collected at MLO. 

FEB 60 MAR 

400 • 

fi! 220 

55 

~390 

~ fi! 50 

~· ~ 210 2 a: • • a: ~380 ~ w 45 

~370 • ~200 • 0.. 

~ 40 ~· • • c c • c •• • 31: 360 • 31: 190 31: • • 

350 

74 76 78 80 82 84 

YEAR 

86 88 90 

30 SEP • 

fi! 25 

2 • •• a: • ~ 20 • ~ •• • c 15 • • • • 

31: • 

10 

74 76 78 80 82 84 86 88 90 

YEAR 

180 

74 76 78 80 82 84 

YEAR 

86 88 90 

150 OCT 

~ 140 ••• • • • 2 --=------· a: 

~ 130 • • ~ • • 

; 120 • • 

110 

74 76 78 80 82 84 86 88 90 

YEAR 

460 ~~.~~~-D-EC~~~ 

450 

~440 :II 

a: 430 

~420 

5410 

31: 400 

•• • -~·...:!·~·~ .... -·""ii • .- • • 

• 

390"-'-_._._._ ...................................... ~~~ 

74 76 78 80 82 84 86 88 90 

YEAR 

35 

76 78 80 82 84 

YEAR 

86 88 90 

360 NOV 

fil 350 • : 340 • • ' w • • • • 0.. 

~ 330 

; 320 • • 

• 310 

74 78 78 80 82 84 

YEAR 

86 88 90 

Figure 3.1. The month-by-month year-to-year variation is surface global solar irradiance at SPO. Significant trends are seen for January and 

February with a clear lack of any indication of a trend in most other months. 

21 
z 

§ 

a 

z 

2 

0.9S 

0.92.S 

0.9 

0.87S 

0.8~ -t--::60!""-:6:'!'2_64..,.........,66..,........68--70~7-2-74_7_6 -7~8-80_8.J..2'-8~4__,8_6 -8-8-90--l92 

~ 

Figure 3.2. MLO direct solar transmission with a 7-month lowess 

smoother. The solid line plotted for the smoother reveals a persistent 

annual cycle, the instantaneous amplitude of which can be determined 

by complex demodulation. 

Figure 3.3. The coherency between the equatorial zonal winds and the 

amplitude of the annual cycle in the MLO transmission record. The 

peak near a frequency of 0.037 (period of 27 months) corresponds to the 

dominant quasi-biennial oscillation in the equatorial zonal wind field. 

Although the total amount of material ejected from Pinatubo is 

believed to be greater than that from El Chichon, the impact at 

MLO will be less for Pinatubo primarily because the horizontal 

dispersion of the material is substantially different as seen by 

satellite. 

3.2. SPECIAL PROJECTS 

3.2.1. SPEC1RAL RESPONSE CHARACTERISTICS OF 

ROBERTSON-BERGER METERS 

lnJroduction 

Concern over the possible depletion of atmospheric ozone by 

high-flying supersonic aircraft emissions (Climatic Impact 

Assessment Program, U.S. Department of Transportation), and 

an associated predicted increase in biologically damaging UV 

radiation inspired the construction, installation, and operation of 

a network of R-B meters, to measure UV radiation on a 

continuous basis. The design of these instruments was 

essentially that of Robertson (1972). They were placed at 

different latitudes and longitudes in the United States in the 

early 1970s such that the gross seasonal and regional variations 

in UV exposure could be studied and related to human skin 

cancer. A few were placed outside the mainland United States. 

NOAA presently operates 17 U.S. instruments, 2 of which are 

on the Hawaiian Islands. 

These instruments sense a broad wavelength band that is 

meant to simulate the sunburning action spectrum of caucasian 

skin, similar to that of CoblenJz and Stair (1934]. However, the 

design of the instrument did not accurately meet this 

requirement [Berger, 1976], and for this reason it has been 

criticized [e.g., NAS, 1979). The instrument possesses a spectral 

response function (SRF) that is similar in shape to the human 

22 

skin erythemal action spectrum at wavelengths greater than 300 

nm, but the solar UV band it senses is shifted toward longer 

wavelengths several nanometers beyond the human skin 

erythemal action spectrum. The bandwidth of solar UV 

radiation actually sensed by the instrument is ::13 nm at 

half-power wavelengths, and at a solar zenith angle of 30' , the 

band's maximum power wavelength is ::311 nm; whereas, it 

should be ::307 nm if the instrument were to accurately 

simulate the response to the human skin action spectrum 

[DeLuisi and Harris, 1983]. Nevertheless, the band extends 

sufficiently far into the wavelength region of the Huggins ozone 

absorption band such that the meter is sensitive to atmospheric 

ozone absorption of UV radiation, although, not as sensitive as 

it would be if it accurately simulated that of the human skin 

action spectrum. 

Since the SRFs were not measured for each instrument in the 

network until this investigation, it would not be possible to 

directly determine whether changes in their characteristics 

occurred. Nevertheless, by examining the characteristics of a 

sample of several R-B meters that served in the network (about 

one-half the number in the network) it should comprise a 

sufficient set for determining the degree of their mutual 

consistency, and perhaps yield information that would bear upon 

their stability while operating in the network. 

The R-B meter sensor unit is sensitive to temperature 

changes. Blumthaler and Ambach [1986) reported a sensitivity 

change of 8% per 1 O'C change in sensor temperature. The 

instruments should be temperature stabalized to improve their 

accuracy. Details in the construction and design principles of 

the R-B meter are given by Berger (1976). 

To obtain a representative measure of the SRF of an R-B 

meter optical head, the SRFs of five sections of an R-B meter 

optical head are measured and averaged. A few tests have 

shown that more than one run on a specific area is repeatable to 

better than 2%. The most important region is within the range 

between 300 and 330 nm, wherein lies the meter's greatest 

sensitivity to the specttal distribution of the incident solar UV 

radiation. Below 300 nm UV is cut off by ozone and above 330 

UV is cut off by the instrument SRF. 

Figure 3.4 contains six plots representing the SRFs of six 

R-B meters. Numerical tabulations of these plots and their 

standard deviations will be given in a later report. Some 

interesting differences are noted in the 300-330 nm 

wavelength region, although all shapes in this region are 

quite similar. This wavelength region is essentially the band 

of atmospheric UV radiation that is sensed by the instrument. 

No explanation is given for the differences at this time 

except that variations in instrument construction (e.g., filters 

and substrate thickness) are likely to be a cause, combined 

with experimental error in determining the SRFs. Aging 

from long-term field use may also be responsible; however, 

this cannot be assessed because, as mentioned earlier, no 

previous characterization data exist. Nevertheless, these 

instruments have operated in the field for several years for 

more than a decade, and it is quite remarkable that their 

SRFs have retained shape similarity. The CMDL plot in 

Figure 3.5 is the average of the seven R-B meter SRFs. This 

plot is compared with the SRFs obtained from the literature. 
UJ 

I 

Fig. 3.4. Spectral response functions of six R-B meters plotted as 

response versus wavelength. 

The present SRFs are consistent with those of Berger [1976] 

and CIAP [1976] also plotted in Figure 3.5. The fact that the 

SRFs presently measured are so close to earlier determinations, especially Berger's, strongly suggests a possible 

verification of the Jong-term stability of the R-B meter 

network's sensor SRFs. 

Discussion 

Seven R-B meters were subjected to an examination of 

their spectral response characteristics. The SRFs thus far 

measured were found to be quite similar in shape in the UV 

wavelength region sensed by the instrument, i.e., 300-330 

UJ 

"' z 

2 

~ 

I 

z 

... 0 

CIAP 

... 0.1 

BERGER 

... 

CMDL 

o.oi 

0.000\ -t---,..----..---,,---.,--.,---.--~--~--1 

290 300 310 320 330 340 350 360 370 380 

WA VELENGTII 

Fig. 3.5. Average of seven R-B meter spectral response functions 

(CMDL), the human erythemal action spectrum (ERYTHEMA), 

Berger's [1976] spectral response function (BERGER), and the NAS 

[ 1979] spectral response function (CIAP) [after Rober/son, 1972]. 

believed to be partially responsible. The displ acements have 

only a small impact on the agreement among the instruments 

when they are calibrated to agree with a standard as is done 

for the network meters. The results of this investigation are 

nm. However, the wavelength positions among them varied 

by a few nanometers. Experimental error is partially 

responsible for this variation. Variations in the optical 

components, such as filter and substrate thicknesses, are also 

further described in DeLuisi et al. [1992]. Determination of 

the SRFs of all R-B meters in the NOAA network were 

recently completed. All instruments were subjected to a 

maintenance update including cleaning, repainting, electronic repair, and ·calibration and then returned to their 

respective sites. 

3.3. REFERENCES 

Berger, D., The sunburning ultraviolet meter: Design and 

performance, Photochem. and Pholobiol., 24, 187-192, 1976. 

Blumthaler, M., and W. Ambach, Messungen der temperatur 

koeffizienten des Robertson-Berger sunburn meters und des 

Eppley UV-radiometers, Arch. Met. Geophys. Biol., Ser. B, 36, 

357-373. 1986. 

Cess, R.D., E.G. Dutton, J.J. DeLuisi, and F. Jiang, Determining 

surface solar absorption from broadband satellite measurements 

for clear skies: comparison with surface measurements, J. Clim., 

4, 2367-247, 1991. 

CIAP (Climatic Impact Assessment Program), Monograph 5, Part l, 

U.S. Department of Transportation, Washington, DC, 1976. 

Coblentz, M.W., and R. Stair, Data on the spectral erythemic 

reaction of untanned human skin to ultraviolet radiation, J. Res. 

(Natl. Bur. Stand.), 13, 13-14, 1934. 

DeLuisi, J., and J. Harris, A determination of the absolute energy of 

a Robertson-Berger meter sunburn unit, Atmos. Environ., 17, 4, 

751-758, 1983. 

DeLuisi, J., J. Wendell, and F. Kreiner, Spectral response 

characteristics of seven Robertson-Berger meters after long-term 

field use, Pholochem. and Photobiol., in press, 1992 . 

Dutton, E.G., R.S. Stone, D.W. Nelson, and B. Mendonca, Recent 

interannual variations in solar radiation, cloudiness, and surface 

temperature at the South Pole, J. Clim., 4, 848-858, 1991. 

Dutton, E.G., and DJ. Endres, Date of snowmelt at Barrow, Alaska, 

USA, Arct. Alp.Res.,23, 115-119, 1991. 

Dutton, E.G., A Coherence between the QBO and the amplitude of 

the Mauna Loa atmospheric transmission annual cycle, Int. J. 

C/imatol., in press, 1991. 

Dutton, E.G., Annual forcing of the surface radiation balance 

diurnal cycle measured from a high tower near Boulder, 

Colorado,!. Clima te, 3, 1400-1408, 1990. 

Ellis, H.T., and R.F. Pueschel, Solar radiation: Absence of air 

pollution trends at Mauna Loa, Science, 172, 845-846, 1971. 

Foster, J.L., The significance of the date of snow disappearance on 

the Arctic tundra as a possible indicator or climate change, Arel. 

Alp. Res., 21, 60-70, 1989. 

NAS (National Academy of Science), Protection Against Depletion 

of Stratospheric Ozone by Chlorofluorocarbons, National 

Academy of Sciences, Library of Congress Card Catalog Number 

79-57247, 392 pp., 1979. 

Robertson, D., Solar ultraviolet radiation in relation to human skin 

bum and cancer, Ph.D. Thesis, No. THE4866, University of 

Queensland, Australia, 1972. 

23 
4. Carbon Cycle Group 

P.P. TANS (Editor), T.J. CONWAY, E.J. DLUGOKENCKY, D.R. KlTZIS, 

P.C. NOVELLI, K.W. THONING, AND L.S. WA TERMAN 

4.1. CONTINUING PROGRAMS 

4.1.1. IN SITU CARBON DIOXIDE MEASUREMENTS 

The concentration of atmospheric COl was measured with 

continuously operating NDIR analyzers at the four CMDL 

observatories during 1990 as in previous years. Monthly and 

annual mean COl concentrations are given in Table 4.1. 

These values are provisional, pending final calibrations of 

station standards. Revised values for 1988 and 1989 are also 

included. Preliminary selected daily average COl concentrations for 1990 are plotted versus time for the four observatories in Figure 4.1. 

On February 3, the in situ COl measurements at SMO 

were halted due to damage to the sample air intake system on 

Matatula Point from Hurricane Ofa. The sampling tower 

holding the intake lines was destroyed as was a building in 

which a refrigeration system for removing water vapor from 

the sample air was located. Sampling resumed on May 4, 

with a temporary sampling intake mast. During the period 

when the continuous measurements were not being made, the 

frequency of collecting flask samples was increased to 

approximately twice a week. By October, a new building 

and a new sampling mast were installed. The new mast is a 

fiberglass flagpole, 77 feet high, 10 inches in diameter at the 

base, located approximately 30 feet from the original tower 

further out on the Point on a little knoll. The new intake is 

about 20 feet higher than the old one. On October 14, the 

COl NDIR analyzer was changed from a Hartmann-Braun 

URAS -2T to a Siemens ULTRAMAT-5F. This new analyzer 

shows better stability than the URAS-2T. On December 5, 

the analyzer at SPO was also changed from a URAS-2T to an 

ULTRAMAT-5F. 

4.1.2. 

MENTS 

FLASK SAMPLE CARBON DIOXIDE MEASUREIn 1990 the measurement of the global distribution of 

atmospheric col continued. col mixing ratios were 

measured in samples collected at 29 sites of the CMDL 

cooperative flask sampling network (Table 4.2). Provisional 

annual mean COl mixing ratios for 1990 and revised values 

for 1988 and 1989 are also given in Table 4.2. Sampling at 

the U.S. Virgin Islands site (A YI) was discontinued in 1990 

because the cooperating institution, the West Indies 

Laboratory of Fairleigh Dickinson University, ceased 

operations. In anticipation of this closure, sampling was 

begun in Barbados in 1987, so there is an overlap and 

continuing measurements in the Caribbean. Sam piing on 

voyages of the containershlp Southland Star in the Pacific 

Ocean continued in 1990. To increase the temporal 

resolution of the shipboard data, sampling on a second ship, 

the Wellington Star, was begun in 1990. 

TABLE 4.1. Provisional Monthly Mean COl 

Concentrations from Continuous Analyzer Data 

(ppmv, Relative to Dry-Air X85 Mole Fraction Scale) 

Jan. 

Feb. 

March 

April 

May 

June 

July 

Aug. 

Sept. 

Oct. 

Nov. 

Dec. 

Annual 

Jan. 

Feb. 

March 

April 

May 

June 

July 

Aug. 

Sept. 

Oct. 

Nov. 

Dec. 

Annual 

24 

Jan. 

Feb. 

March 

April 

May 

June 

July 

Aug. 

Sept. 

Oct. 

Nov. 

Dec. 

Annual 

BRW 

354.87 

356.23 

356.56 

357.40 

356.83 

355.27 

348.43 

343.10 

345.87 

350.59 

354.28 

357.86 

353. 11 

360.88 

358.16 

359.15 

359.27 

358.74 

357.04 

349.34 

344.48 

346.18 

351.19 

355.81 

358.29 

354.88 

359.81 

359.85 

361.24 

361.04 

360.48 

356.77 

349.49 

345.74 

346.37 

353.81 

356.63 

359.21 

355.87 

MLO 

1988 

350.19 

351.50 

352.11 

353.51 

354.1 6 

353.60 

352.61 

350.32 

348.81 

348.96 

350.09 

351.32 

351.43 

1989 

352.72 

353.16 

353.71 

355.42 

355.67 

355.14 

353.81 

351.40 

349.80 

350.04 

351.28 

352.63 

352.90 

1990 

353.64 

354.81 

355.56 

356.10 

357.04 

356.06 

354.45 

352.67 

350.97 

351.28 

352.73 

354.16 

354.12 

SMO 

349.24 

349.70 

349.35 

350.27 

349.63 

349.66 

349.94 

349.81 

348.94 

349.26 

349.72 

350.58 

349.67 

351.29 

351.62 

351.38 

351.40 

351.66 

350.73 

351.04 

35 1.07 

350.62 

350.21 

350.63 

350.60 

351.02 

351.68 

353.24 

352.22 

352.92 

352.76 

352.82 

352.88 

352.74 

352.90 

353.43 

352.76 

SPO 

348.06 

347.92 

347.98 

348.18 

348.28 

348.50 

348.89 

349.33 

349.63 

349.70 

349.70 

349.69 

348.82 

349.62 

349.68 

349.60 

349.68 

349.92 

350.22 

350.58 

351.00 

351.08 

351.24 

351.29 

350.87 

350.40 

350.76 

350.57 

350.64 

350.91 

351.25 

351.58 

352.06 

352.40 

352.70 

352.74 

352.74 

352.30 

351.72 
-

E 

a. 

a. 

-

0 

0 

Maune Loo 

360 

350 

Samoa 

360 

350 

370 

South Pole 

360 .... 

350 lo340~~~ ~~~~~~~ ~~~~~--' 

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOi DEC 

1990 

Fig. 4. 1. Preliminary selected 1989 daily average C02 concentrations from the in situ measurements at BRW, MLO, SMO, and SPO. 

As noted in last year's Summary Report we have begun 

the conversion to 2.5-L flasks equipped with Teflon 0-ring 

stopcocks. Laboratory and field tests have shown that C02 , 

CO, and isotopic ratios are more stable in these flasks. In 

1990 flasks with Teflon 0 -rin gs were in use at 15 sites. Also 

during 1990, we began routine deployment of a new portable 

sampler (Martin and Kitzis Sampler, abbreviated MAKS) to 

replace the design in use since 1980 (the P3). The new 

design includes a more powerful pump and battery, and 

several modifications intended to increase the probability 

that a person with little or no technical background can 

collect an uncontaminated sample. Whenever possible, we 

are providing face-to-face training for sample collectors 

when we deploy the new sampler. Training takes place 

preferably in Boulder or at the sampling site if travel to 

Boulder is impractical. 

The new sampling unit weighs 24 pounds, and can be used 

with the old 0.5-L and the new 2.5-L flask pairs. A light 

shield is incorporated into the unit to reduce the possibility 

of any CO photochemistry during the sampling procedure. 

The air intake is now 16 feet above the unit to reduce C02 

contamination from the sample taker and from vegetation in 

the immediate surroundings. Final pressure is held constant 

by a backpressure regulator so that the integrity of the 

TABLE 4.2. Provisional 1988-1990 Annual Mean C02 

Concentrations From the Flask Network Sites 

Code 

ALT 

AMS 

ASC 

AVI 

AZR 

B~E 

BMW 

BRW 

CBA 

CGO 

CHR 

CMO 

GMI 

llBA 

KEY 

KUM 

MBC 

MID 

MLO 

NWR 

PSA 

RPB 

SEY 

SGI 

SHM 

SMO 

SPO 

STM 

SYO 

Station 

Alen, N.W.T., Canada 

Amsterdam Island 

Ascension Island 

St. Croix, Virgin Islands 

Tercei ra Island, Azores 

Bermuda (east coast) 

Bermuda (west coast) 

Barrow, Alaska 

Cold Bay, Alaska 

Cape Grim, Tasmania 

Christmas Island 

Cape Meares, Oregon 

Guam, Mariana Islands 

Ilalley Bay, Antarctica 

Key Biscayne, Florida 

Cape Kumukahi, Hawaii 

Mould Bay, Canada 

Midway Island 

Mauna Loa, Hawaii 

Niwot Ridge, Colorado 

Palmer Station, Antarctica 

Ragged Point, Barbados 

Mahe Island, Seychelles 

South Georgia Island 

Shemya Island, Alaska 

American Samoa 

South Pole, Antarctica 

Ocean Station M 

Syowa Station, Antarctica 

1988 

353.0 

349.5 

350.4 

351.5 

351.6 

353.4 

352.3 

348.9 

351.3 

352.6 

352.I 

349.7 

352.7 

351.4 

353.5 

352.9 

351.3 

351.9 

349.6 

351.5 

350.3 

(] 

353.l 

350.2 

349.0 

352.4 

349.3 

C02 (ppm) 

1989 

355. 1 

350.5 

351.6 

353.5 

351.1 

354.9 

354.4 

350.3 

353.3 

354.4 

353.5 

l I 

354.4 

352.9 

355.5 

354. 1 

352.8 

353.3 

350.9 

352.9 

352.2 

l I 

354.5 

351.7 

350.6 

354.0 

[) 

1990 

355.5 

[ l 

352.9 

[I 

353.9 

355.2 

355.3 

356.0 

355.3 

351.6 

354.3 

355.4 

354.2 

I I 

356.3 

354.3 

356.0 

355.1 

354.1 

354.7 

351.9 

354.7 

353.2 

[I 

355.0 

352.8 

351.8 

354.8 

I l 

Square brackets indicate insufficient data to calculate annual mean. 

connections can be checked. We are starting to employ 

Teflon connectors to the 14/35 tapered glass joints to 

eliminate the use of, and possible contamination by, vacuum 

grease. These connectors were developed and tested 

extensively by the Carbon Cycle Group. Further development of the MAKS is continuing. We are currently testing a 

thermo-electric cooling stage to dry the air stream before it 

enters the flasks. 

The CMDL flask network C02 data are summarized in 

Figure 4.2 where annual means for each site are plotted 

versus latitude for the period 1981-1990. Two important 

features of this figure are the interannual and spatial 

variability of the C02 growth rate, and the shift in the North 

Pole-to-South Pole C02 difference from =3 ppmv during 

1981-1987 to ===4 ppmv during 1988-1990. The variations in 

emissions of C02 from fossil fuel combustion [Marland el 

al., 1990] arc too small to explain the changes observed in 

the atmosphere. Therefore, these data reflect significant 

temporal and spatial variability in the exchanges of carbon 

between the atmosphere and oceans, and between the 

atmosphere and the marine and terrestrial biospheres. 

To investigate this variability, we have used a 2-

dimensional (latitude and height, 2-D) atmospheric transport 

model [Tans et al., 1989] to calculate the C02 sources and 

25 
::1· l 1 1 

~ ::: v1i-·tl"' ~""~twV,u~U~ \VAi. ~~1 JAN r£8 KA.A APR ..._.y .J.1" .U.. AL.G SEP OCl tL./V ctC 

1715() 0 ~ 

: '.~ti,~~ ~y~\~k~J)~11fiv1 ·--· ~-- ---~- · • __ _l JAN FEB MAA ..s:f\ ..UY ..Ul ll ALG SCP OCI t/J'I [\ C 

1990 

fig. 4.6. Edited, unselected daily average methane mixing ratios for 

1990: a-BRW and b-MLO. Gaps in the data are due to instrument 

malfunction. 

Cl-14 m1xmg ratio were made from flask samples collected 

approximately weekly at 28 sites in the CMDL cooperative 

flask sampling network. Also, flasl,c samples were collected 

from aboard the container ship Southland Star every 5' in 

latitude from 35'S to 30' N. Provisional annual mean mixing 

ratios from the flask data are shown in Table 4.3 and Table 

4.4. Some sites do not have annual means listed. At 

Amsterdam Island we have only received and analyzed 

samples which were collected through May. At Azores, 

sampling problems continued; 6 months of data are missing 

due to U.S. Air Force commitments for Operation Desert 

Shield. A new station is under construction up-wind from 

the current sampling site at Halley Bay. This may be the 

reason for severe contamination in almost all of the samples 

collected at that site during 1990. For Seychelles and 

Syowa, 2 months at each site had insufficient data to 

calculate monthly means. Mean values for those months 

were determined by interpolation and combined with the 

remainder of the data to calculate the annual means listed. 

A new flask measurement system, Carle 7, was put into 

service in 1990. This system allows for simultaneous 

measurement of CH4, CO, and H2 on two different gas 

chromatographs. Previously CH4 and CO were measured on 

separate analytical systems, and the CO system was not 

automated. Currently, all three species are measured with a 

single manipulation of the flasks, and the chromatography 

for each species can be optimized independently of the other. 

The measurement techniques are the same as before; CH4 is 

detected by flame ionization, and CO and H2 are detected by 

first producing Hg atoms by the reactions CO + HgO -> C02 + 

Hg and 1-12 + HgO -> H20 + Hg, and then detecting the Hg 

atoms by resonance absorption. The carousel is still used to 

set up eight flasks for unattended analysis. A comparison 

between Carle 4 and Carle 7 was made using test flask 

samples flushed and filled in series from a tank of natural 

air. Eight flasks were measured on each system for CH4 . In 

TABLE 4.3. Provisional 1990 Annual Mean CH4 Mixing 

Ratio Concentrations From the Flask Network Sites 

Code Station CH4 , ppbv 

ALT Alert, N.W.T., Canada 1783.7 

AMS Amsterdam Island [ l 

ASC Ascension Island 1656.7 

AZR Terceira Island, Azores l I 

BME Bermuda (east coas1) 1756.7 

BMW Bermuda (west coast) 1744.9 

BRW Barrow, Alaska 1798.2 

CBA Cold Bay , Alaska 1778.3 

CGO Cape Grim, Tasmania 1644.3 

CHR Christmas Island 1668.9 

CMO Cape Meares, Oregon 1759.8 

GMI Guam, Mariana Islands 1708.6 

HBA Halley Bay, Antarctica [ l 

KEY Key Biscayne, Florida 1741.4 

KUM Cape Kumuk ahi, Hawaii 1723.4 

MBC Mould Bay, Canada 1790.3 

MID Midway Island 1742.2 

MLO Mauna Loa, Hawaii 1711.5 

NWR Ni wot Ridge, Colorado 1733.0 

PSA Palmer Station, Antarctica 1641.0 

RPB Ragged Point, Barbados 1716.8 

SEY Mahe Island, Seychelles 1670.0 

SGI South Georgia Island [ l 

SHM Shemya Island, Alaska 1784.7 

SMO American Samoa (Matatula Point) 1648.1 

SPO South Pole, Antarctica 1642.4 

STM Ocean Station M 1778.4 

SYO Syowa Station, Antarctica 1642.4 

Square brackets indicate insufficient data to calculate annual 

mean. 

TABLE 4.4. Provisional 1990 Annual Mean Mixing Ratios 

From the Southland Star Shipboard Flasks 

28 

Latitude CH4 (ppb) 

35"S 1643.4 

30'S 164 1.7 

25'S 1643.6 

20'S 1647.0 

15'S 1644.9 

!O'S 1656.0 

S'S 1665.9 

Equator 1669.9 

5'N 1681.6 

lO'N 1669.8 

15"N 1721.3 

20'N 1724. 1 

25'N 1729. 1 

30'N 1744.1 

addition to the test flasks, numerous tank calibrations were 

made on Carle 7. No systematic difference was observed 

between Carle 4 and Carle 7 suggesting that switching to 

Carle 7 for routine flask analysis would not result in any bias 
in our CH4 data. An important aspect of these measurement 

systems is the precision. The mean difference between the 

two aliquots measured from 857 flasks on Carle 7 was (-0.32 

± 3.4) ppbv. This is an improvement over Carle 4. Finally, 

combining the CO/H2 measurement with CH4 on the same 

system has made us more efficient; Carbon Cycle Group 

personnel now spend approximately 20 staff-hours less per 

week on flask analysis. 

The average seasonal cycles for CH4 over the period 1983 

through 1990 determined from the flask sample data, with 

the trends removed, are shown in Figures 4.7a for BRW and 

4.7b for SPO. At BRW, the seasonal cycle is mostly due to 

seasonality in the natural wetland sources and the 

photochemical sink. The peak-to-peak amplitude is :.::54 

ppbv. The large decrease in CH4 during summer months is 

due to chemical destruction by reaction with hydroxyl (OH) 

radical OH + CH4 -> H20 + CH3; k(298 K) = 6.35 x 10-15 

cm3 molecuJe·1s·1• The multiple maxima are unexplained, 

but some possibilities exist. For example, the fall maximum 

in October and November may be due to CH4 released when 

high northern latill•de wetland lakes tum over due to sinking 

cold water just before freeze over. The sinking water may 

disturb sediments which trap bubbles of CH4 produced by 

anaerobic bacteria. At SPO, a seasonal sink term and 

transport of CH4 from the northern hemisphere are responsible for the seasonal cycle observed there, ::::.30 ppbv peakto-peak. 

Over the entire period of the CMDL CH4 measurements, 

the average increase in CH4 has been ""11 .9 ppbv yrt. 

Detailed analysis has shown that the growth rate has not 

been constant over time. The Oask data can be averaged 

using the techniques described in Steele el al. [1987], to 

determine global monthly means for CH4 • The data fitting 

routines of Thoning et al. [ 1989]. have been applied to these 

monthly values. Briefly, a function consisting of a quadratic 

polynomial plus four seasonal harmonic terms is fit to the 

global monthly means. The residuals are then filtered with a 

low-pass filter in the frequency domain to separate 

variability occurring on time-scales of the order of 1 year 

and longer, and these values are added back to the quadratic 

trend portion of the original function. The resulting 

composite shows the trend in CH4 , including long-term 

variations in that trend. The derivative of this curve gives 

the instantaneous smoothed growth rate, and it is shown for 

the flask data through 1990 in Figure 4.8. Not all sites listed 

in Table 4.3 are included; those with limited data and the 

high altitude sites at MLO and NWR are excluded. Two 

features apparent in Figure 4.8 are: l) The growth rate of 

CH4 has decreased over the period of our measurements. 

This decrease is due to long-term changes in the sources or 

sinks of CH4 • From our data, it is impossible to determine 

which is the most in1portant contributor. 2) Significant 

interannual variations in the CH4 growth rate appear to ex ist. 

This is most likely due to interannual variations in the 

strengths of CH4 sources, but at this time, we cannot rule out 

the possibility that it may, in part, be due to an artifact of our 

data analysis procedures. 

-· 

-·· 

·20 

·?> 

2> 

20 

.. 

10 

~ s 

'6 ·• 

· 10 

... 

·20 

·2> 

(a) 

..lA.N FEB ~ IPA ~y .J..N .l.L N.Al SEP OCT t(JV OEC 

MONTH 

(b) 

Jm FEB KAA ~ MAY .J..11 ..U.. M..O SEP OCT t.tlV CEC 

MONTH 

Fig. 4.7. Average seasonal cycles, with trend removed, for the 

period 1983 through 1990 fora-BRW and b-SPO. Seasonal cycle is 

extracted using the techniques from Thoning et al. (1 989]. 

29 

.. 

c 

.. 

s= 

.. 

.. 

x 

YEAR 

Fig. 4.8. Globally averaged instantaneous growth rate, with the 

seasonal cycle removed, for atmospheric CH4 determined from 

CMDL flask network data for 1983- 1990. 
4.1.5. FLASK MEASUREME:-ITS OF CARBON MONOXIDE 

During 1990 the measurement of CO concentrations in air 

samples continued. Samples were collected in flasks having 

two different volumes, either 0.5 L or 3 L. Samples in 0.5-L 

flasks were collected using our portable pumping system, 

which filled a pair of glass flasks, fitted with two Teflon 

0-ring stopcocks, with air lo a final pressure of about 1.5 

atm. The 3-L samples were collected in previously 

evacuated flasks having one Teflon 0 -ring stopcock, which 

were opened to the atmosphere at the site. The sampling 

methods used are detailed in Steele et al. [ 1987). Air 

samples were analyzed for CO using the mercuric oxide 

reduction technique. Until November 1990, we used a 

semi-automated instrument for flask analysis. In December 

we began analyzing CO using a more fully automated system 

(see section 4.1.4 ). The CO working standards are secondary standards to the NOAA/CMDL CO gravimetric 

standards [Novelli et al., 1991). 

Laboratory experiments have previously shown that the 

concentration of CO in air contained in the 0.5-L and 3-L 

flasks was stable (to within 1 ppbv or about 1 %) over the 

course of 2 weeks and at least 4 weeks, respectively. 

Experiments also showed that air in flasks exposed to even a 

few minutes of sunlight exhibited an increase in CO over 

time, probably as a result of the photo-oxidation of organic 

molecules which coat the inside walls of the fl ask. To 

minimize light-enhanced CO levels, all flasks used for CO 

sampling were coated with two layers of white adhesive tape. 

Additional experiments that compared the growth of CO in 

taped 0.5-L and 3-L flasks indicated that the smaller flasks 

were somewhat more susceptible to light-induced CO 

growth. In the field, sample takers were instructed to 

minimize the exposure of the flasks to sunlight. The new 

MAKS sampling unit minimizes light exposure during flask 

filling (see section 4.1.2). 

CO concentrations were measured in samples from eight 

stations during 1990 (see Table 4.5). These sites were 

Code 

ASC 

BRW 

CHR• 

GMI 

KUM 

ML02 

NWRt 

SMO 

TABLE 4.5 Provisional 1990 Annual Mean CO 

Concentrations From the 0.5 1 Flasks 1 

Station 

Ascension Island 

Barrow, Alaska 

Christmas Island 

Guam, Mariana Islands 

Cape Kumakahi, Hawaii 

Mauna Loa, Hawaii 

Niwot Ridge, Colorado 

American Samoa 

CO (ppbv) 

88.6 (10.3) 

152. 3 (22. 9) 

79.6 ( 5.8) 

104.7 ( 8.5) 

109.9 (12.8) 

101.6 (11.4) 

122.5 ( 8.7) 

64.4 ( 5.2) 

•Concentrations are reported in units of parts per billion by mole 

fraction, values in parentheses are the pooled standard deviations. 

Samples al Christmas Island were collected only in 3-L flasks, all 

other values were determined from samples collected in 0.5-L Oasks. 

tMLO and NWR are mountain sites, all others are in the boundary 

layer. 

chosen based on their geography, and from a more practical 

standpoint, upon the basis of how long a time it took for the 

flask to return to Boulder after sampling. At all stations 

except CHR, samples were collected in 0.5 -L glass flasks. 

At CHR, samples were collected only in 3-L flasks. At three 

sites (BRW, KUM, and SMO), we collected air samples in 

both 0.5-L and 3-L glass flasks. Samples were collected 

approximately once per week at all stations other than GMI. 

At GMI, air samples were collected twice weekly. 

The 1990 provisional annual mean CO concentrations 

measured in 0.5-L glass flasks and referenced to the CMDL 

reference scale, are provided in Table 4 .5. The data have 

been selected to remove erroneous values due to sampling 

and instrumental problems. Table 4.6 compares the calculated annual mean concentrations determined in 0.5-L flasks 

to those measured in 3-L flasks. Monthly mean concentrations were calculated directly from the measured weekly CO 

concentrations, and the arrnual values are the arithmetic 

means of the monthly means. Figure 4.9 compares the CO 

concentrations determined in 0.5-L flasks and 3-L flasks at 

BRW. This comparison gives us an estimate for the 

repeatability of the sampling and measurement procedure, 

plus the effects of natural atmospheric variability on a time 

scale of minutes. For data collected at BRW, the standard 

deviation of the individual samples from the linear fit is 2.4 

ppbv. 

In addition to the arithmetic calculation of monthly 

means, we also used a curve-fitting method to calculate the 

monthly mean concentrations. Whereas the arithmetic 

calculations could be biased by missing data, the curvefitting approach interpolates over periods of absent data. 

Specifically, the smoothing routine uses the flask data to 

characterize the seasonal CO cycle as a linear combination of 

four harmonics, and then uses the curve to calculate monthly 

means. The arrnual means calculated using the two averaging methods differed by at most 1.5% for each station and 

were not significantly different from one another. Figure 

4.10 presents the relationship for the curve fit monthly mean 

and the arithmetic mean CO concentrations determined at 

BRW. This figure suggests that the uncertainty of the 

monthly means due to collecting weekly samples is in the 

vicinity of 1.5% at BRW (annual average). 

30 

TABLE 4 .6 Comparison of Annual Mean CO 

Concentrations Determined in 

0.5- and 3-L Glass Flasks 

CO Concentration (ppbv) 

Station 0.5 1 3 1 

BRW 

KUM 

SMO 

152.3 (22.9). 

109.9 (12.8) 

64.4 ( 5.2) 

152.9 (24.0) 

108.3 (12.5) 

64.2 ( 4.5) 

•Values in the parentheses are pooled standard deviations around 

the mean. 
240 

220 

200 

"' // .:< 

"' 0 180 

.:;:: 

_J 

"') 160 

u 

c 

0 

u 140 • 0 

u 

120 • 

100 

100 120 140 160 180 200 220 240 

CO Cone (0.5 L Flask) 

Fig. 4.9. Comparison of monthly mean CO concentrations 

determined in 0.5-L and 3-L glass flasks collected at BRW. Both 

types of flasks were taped with white adhesive tape to minimize 

light effects. Monthly means were calculated simply as the mean of 

the weekly concentrations. The line is described by Y = -0.97 

(0.038) + 1.012 (0.016)X. Values in parentheses are the standard 

error. 

c 

0 

220 

200 

~ 180 

>.. 

:5 

c 160 0 

:::;; 

i,;: 140 

"' i'.: 

:> 

u 120 

100 

• 

• • 

• 

•• 

• 

•• 

• 

•• 

80 L_~_J_~-1-~~'--~-'-~-'- ~~~~ 

80 100 120 140 160 180 200 220 

Arithmetic Monthly Meon 

Fig. 4. 10. Comparison of monthly mean CO concentrations for 

BRW calculated arithmetically to those calculated using a curve 

fitting technique. The line is described as Y = 2.69 (0.182) + 0.991 

(0.01 S)X. Values in parentheses are the standard error. 

Figure 4.11 plots the 1990 CO concentration time series at 

BRW. The monthly mean concentrations determined for 

samples collected in both 0.5-L and 3-L fl asks are shown. 

The seasonal cycle is clearly evident, with highest concentralions in the winter and with lower levels observed in the 

summertime. This seasonal cycle has been observed 

previously in both hemispheres [Dianov-Klokov and 

Yurganov, 1981, among others] and is believed to reflect the 

seasonal CO oxidation via the reaction with OH. 

Figure 4.12 presents the 1990 annual mean CO concentrations plotted as a function of latitude. For comparison, the 

10-year average annual mean determined at Cape Point, 

South Africa, by Seiler and coworkers is also plotted. The 

concentration of CO clearly decreases from north to south. 

Concentrations at the high altitude sites, NWR and MLO, are 

slightly lower than might be expected for ground-level sites 

at the corresponding latitudes (also compare annual mean 

concentrations for KUM and MLO in Table 4.4). This 

reflects the general decrease in CO mixing ratios with 

altitude observed in the northern hemisphere [Seiler, 1974]. 

The annual mean CO concentration at ASC (8' S) is about 15 

ppbv higher than might be expected in comparison to that of 

CHR (2' N) and SMO (14' S). Model calculations have 

indicated that this site will be influenced by transport from 

emissions due to biomass burning on the African continent 

(J. Logan, personal communication, 1991 ), and enhanced 

ozone levels measured at ASC have been attributed to 

African fires [Fishman et al., 1991]. However, we observe 

no apparent elevation of C02 at ASC relative to other 

stations at similar latitudes, as would be expected if ASC 

were affected by combustion emissions. 

The CO concentration gradient between 7 1 ' N and 34' S 

calculated from the data presented in this work is approximately 100 ppbv. This estimate agrees well with data 

collected previously by other groups [Seiler, 1974; DianovKlokov et al., 1989] . 

31 

~ 

.D 

a. 

!:; 

c 

.2 

g 

c 

"' u 

c 

0 

u 

0 

u 

240 

220 

200 

180 ~v ·""\ I 

160 

140 \ / " 120 

100 "":::::c:· 80 

60 

40 

20 

0 L-_L~L--L~'---'--~'---"-~~_._~~_._~ 

Jon Feo Mor Apr Moy Jun Jul Aug Sep Oct Nov Dec Jon 

Time (months) 

Fig. 4.11. 1990 monthly mean CO at BRW. Dashed line and solid 

circles represent 0.5-L fl asks. Solid line and inverted triangles 

indicate 3-L flasks. 
200 ,-

175 

........ 150 .D 

a. 

a. 

~ 

c 125 0 

~ c 100 v 

u 

c 

0 

0 75 

c 

0 

v 

~ 50 

25 

-80 -60 - 40 -20 0 20 40 60 80 

Latitude 

Fig. 4.12. Provisional 1990 annual mean CO concentrations at the 

eight sites where CO is measured as a function of latitude. Inverted 

triangles are high elevation sites (MLO and NWR). Data for 34"S are 

the 8-year annual average (1979-1987, excluding 1985) mean CO 

concentration at Cape Point, South Africa, from Brunke et al. (1990). 

Error bars indicate the pooled standard deviation around the mean. 

4.2. REFERENCE GAS STANDARDS 

4.2.1. CARBON DIOXIDE ST A.'l'DARDS 

The calibrations of C02-in-air reference gas tanks 

cominued in 1990; on 116 days, 236 tanks were calibrated. 

All C02-in-air reference gas tanks used by CMDL are now 

being filled with dry ambient air from Niwot Ridge (NWR), 

Colorado, in aluminum tanks. The aluminum tanks show 

better stability for C02 than the steel tanks that have been 

used previously. In 1990, 121 tanks were filled in 47 days at 

NWR. Included among these were 15 large aluminum 

cylinders that will eventually replace the current set of 

secondary standard gases. These 15 tanks were filled in 

1989, but a problem with the stability of the C02 concentration for several minutes after the tank valve was opened was 

noticed. The valves on all these tanks were changed from 

packless stainless steel to packless brass valves, since this 

problem did not occur with previous aluminum cylinders 

using brass valves. The new set of 15 gases range from 250 

to 500 ppmv C02 and will be calibrated by the central C02 

laboratory at SIO in 1991. 

Construction of a system for performing primary 

calibrations of the mole fraction of C02 in reference gases 

began in 1990. A 12-L volume is filled with a sample of 

reference · gas from a compressed gas cylinder, and the 

pressure and temperature are measured. After the C02 in the 

sample has been separated from the air by pumping the 

sample through a trap cooled with liquid nitrogen, the C02 is 

transferred to a ::::::4 cc volume, and the pressure and 

temperature of the collected C02 is measured. The pressure 

and temperature data and the precise volume ratio of the 12 

L and 4 cc volumes, along with corrections for the nonideality of the gases, are used to calculate the mixing ratio of 

the C02 in the sample. Pressure is measured with a high 

precision quartz-spiral pressure gauge manufactured by 

RUSKA. Temperature is measured using platinum resistance 

thermometers. The volumes and pressure gauge are 

contained in a cabinet that is temperature controlled to Jess 

than 0.1 ·c. The system is highly automated with valve 

switching and pressure and temperature measurements 

controlled by computer in order to reduce the time and skill 

required by the operator, as well as to increase the 

repeatability of each measurement. 

4.2.2. METHANE STANDARDS 

All standards used to determine CH4 m1xmg ratios 

reported by CMDL are natural air. It is critical to any 

long-term time series of measurements that the trace gas 

composition of the standards does not change over the period 

of the measurements. Figure 4.13 shows the calibration 

history of the primary standards used since the start of the 

CH4 measurement program in 1983. All cylinders are 

referenced against cylinder number 259 that was purchased 

from the Biospherics Company in 1983. Each of these 

cylinders has sufficient air remaining in it so that if they are 

used wisely, they may be calibrated twice a year for the next 

30 years. 

Three different cylinder materials are represented in 

Figure 4.13: aluminum, steel, and stainless steel. The air in 

the aluminum and steel cylinders is natural air which was 

dried to less than 1 ppmv of water before being pumped into 

the tank. The stainless-steel cylinders are also natural air, 

but the air in them was collected without drying. It is highly 

unlikely that the trace gas composition of all six cylinders 

could be changing in exactly the same mariner. Therefore, 

we feel confident that our CH4 time series is free from bias 

due to the calibration tanks used, and the trends we report 

are not affected by changes in the composition of our 

reference gases with time. 

'758 

1725 

-,. Pee 

a. 

~ 1615 

.. 

J: 

u 1'59 

.,z, 

1609 

11174 

--~~~--- 1''Zll 

.... 

'" 

• •• 

H7' 

1983 1984 1'85 1911 1987 1111 l989 1t98 1991 

32 

Fig. 4.13. 

standards. 

Calibration history of :-.!OAA/CMDL primary CH4 
In addition to the primary standards, secondary standards 

are used for in situ measurements at the observatories. 

These are extensively calibrated against the primaries in 

Boulder and the secondaries at the observatories. Once a 

secondary standard is nearly exhausted, it is returned to 

Boulder for further comparison with the primaries. Unlike 

the primaries, the secondaries are not retained indefinitely. 

In 1990, Carle 4 was retired from flask analysis and 

dedicated to standard calibrations. A subset of our primary 

standards is calibrated periodically on Carle 7 to insure that 

the consistency of our calibration scale is maintained on 

that instrument. 

4.3. SPECIAL PROJECTS 

During May and June, with the cooperation of the Blue 

Star Line (London and San Francisco), regular sampling at 

5' latitude intervals was initiated on the M!V Wellington 

Star to complement the ongoing program started in 1986 on 

the M!V Southland Star [Schnell and Rosson, 1987). L. 

Waterman sailed on Voyage 1281 (May 20-June 13) from 

Los Angeles to Auckland, New Zealand, to investigate the 

suitability of using a MAKS unit aboard the ship with 2.5-L 

flasks and the standard flushing technique and to train the 

deck officers to operate the equipment. On the basis of this 

experience, it was decided to go back to the simpler 

evacuated flask technique that was being used on the first 

vessel. The possibility of extending the sampling south of 

30'S latitude was also investigated. The idea was discarded because the sailing times between ports, Auckland 

to Wellington to Lyttelton, are brief and the ship stays 

close to land. A total of 239 samples was collected on the 

M!V Wellington Star during the first year (May-December) 

of operation. 

4.4. REFERENCES 

Brunke, E.G., H.E. Scheel, and W. Seiler, Trends of tropospheric CO, 

N20, and CH4 as observed at Cape Point, South Africa, Atmos. 

Environ., 24A, 585-595, 1990. 

Crutzen, P.J., and M.O. Andreae, Biomass burning in the tropics: 

Impact on atmospheric chemistry and biogeochemical cycles, 

Science, 250, 1669-1678, 1990. 

Dianov-Klokov, V.I., and L.N. Yurganov, Spectroscopic study of the 

global time-space distribution of atmospheric CO, Tel/us, 33, 

262-273, 1981. 

Dianov-Klokov,V.1., L.N. Yurganov, E.I. Grechko, and A.V. Dzhola, 

Spectroscopic measurements of atmospheric carbon monoxide and 

methane. I. Latitudinal Distribution, J. Atmos. Chem .. 8, 139-151, 

1989. 

Fishman, J., K. Fakhruzzaman, B. Cros, and D. Nganga, Identification 

of widespread pollution in the southern hemisphere deduced from 

satellite analyses, Science, 252, 1693-1696, 1991. 

Marland, G., T.A. Boden, R.C. Griffin, S.F. Huang, P. Kanciruk, and 

T.R. Nelson, Estimates of C02 emissions from fossil fuel burning 

and cement manufacturing, based on the United Nations energy 

statistics and the U.S. Bureau of Mines cement manufacturing data. 

ORNL/CDIAC-25, Nwnerical Data Package NDP-30, 712 pp, Oak 

Ridge National Laboratory, Oak Ridge, TN, 1990. 

Novelli, P.C., J.W. Elkins, and L.P. Steele, The development and 

evaluation of a gravimetric reference scale for measurements of 

atmospheric carbon monoxide, J. Geophys. Res., 96, 

13,109-13,122, 1991. 

Schnell, R.C., and ~. Rosson (Eds.), Geophysical Monitoring for 

Climatic Change, No. 15: Summary Report 1986, 155 pp., NOAA 

Air Resources Laboratory, Boulder, CO, 1987. 

Steele, L.P., PJ. Fraser, R.A. Rasmussen, M.A.K. Khalil, T.J. 

Conway, A.J. Crawford, R.H. Gammon, K.A. Masarie, and K.W. 

Thoning, The global distribution of methane in the troposphere, J. 

Atmos. Chem., 5, 125-171, 1987. 

Seiler, W., The atmospheric cycle of CO, Tel/us, 268,118-135, 1974. 

Tans, P.P., T.J. Conway, and T. Nakazawa, Latitudinal distribution of 

the sources and sinks of atmospheric carbon dioxide derived from 

surface observations and an atmospheric transpon model, J. 

Geophys. Res .. 94, 5151-5172, 1989. 

Thoning, K.W., P.P. Tans, and W.D. Komhyr, Atmospheric carbon 

dioxide at Mauna Loa Observatory, 2, Analysis of the 

NOAA/GMCC data, 1975-1985, J. Geophys. Res .. 94, 8549-8565, 

1989. 

33 
5. Aerosol, Ozone, and Water Vapor Group 

D. HOFMANN, B. BODIIAINE, R.D. EVA~S. R.D. GRASS, J. HARRIS, W. K0~1HYR, ANDS . OLTMANS 

5. 1. CONTINUING PROGRAYlS 

5.1. 1. SURFACE AEROSOLS 

Barrow 

The aerosol monitoring program at BRW was initiated in 

1976 with the installation of a Pollak CN counter as the CN 

calibration standard, a G.E. automatic CN counter for routine 

operations, and a four-wavelength nephelometer for the 

measurement of aerosol scattering extinction coefficient (asp) 

at 450-, 550-, 700-, and 850-nm wavelengths. A TSI (butanolbased) CN counter was installed in March 1990 and will 

undergo a I-year comparison with the existing G.E. CN 

counter before the G.E. counter is permanently retired. 

Aerosol absorption coefficient (crap) has been measured 

continuously with an aethalometer since April 1988. The 

BRW data record was presented by Quakenbush and 

Bodhaine [1986) and Bodhaine [1989). 

Mauna Loa 

The aerosol program at MLO was initiated in 1974 with 

the installation of Pollak and G.E. CN counters and a 

four-wavelength nephelometer. A TSI CN counter was 

installed in May 1988 and, after a 1-year overlap with the 

G.E. automatic CN counter, the G.E. counter was retired. 

The comparison between the TSI and G.E. CN counters at 

MLO was reported in the Summary Report for 1989 [Komhyr 

and Rosson, 1990]. Aerosol absorption has been measured 

with an aethalometer since Apri I 1990. The MLO data 

record was presented by Massey et al. (1987]. 

Samoa 

The aerosol program at SMO was initiated in 1977 with 

the installation of Pollak and G.E. CN counters, and a 

four-wavelength nephelomcter. A TSI CN counter will be 

installed in 1991 and will undergo an overlap period with the 

G.E. CN counter before the G.E. counter is retired. There 

are no current plans for installing an acthalomctcr at SMO. 

The SMO data record was presented by Bodhaine and 

DeLuisi (1985]. 

South Pole 

The aerosol program at SPO was initiated in 1974 with the 

installation of Pollak and G.E. CN counters. A fourwavclength nephelometer was installed in January 1979; a 

TSI CN counter was installed in January 1989; and an 

aethalometer was installed in December 1986. The SPO data 

record was presented by Bodhaine el al. (1986, 1987) and 

Bodhaine and Shanahan (1990] . 

Discussion of Data 

CN concentration was measured continuously with G.E. 

and/or TSI CN counters, and daily calibration points were 

provided by Pollak CN counters at all stations (twice daily at 

SPO). After a TSI CN counter is installed at a station, a 

1-year overlap with the existing G.E. CN counter is 

performed. All G.E. CN data have been scaled to agree with 

the Pollak CN counter observations. Since the TSI instrument is a single particle counter and is considered to be an 

absolute instrument, its data are not scaled to agree with the 

Pollak counter. However, Pollak counter observations are 

being continued at all stations to maintain the continuity of 

the record and to serve as quality control for the TSI 

instrument. 

Figure 5.1 shows daily geometric means of CN concentration (lower portion of each plot), a sp (middle portion of each 

plot), and Angstrom exponent (upper portion of each plot) at 

the CMDL stations for 1990. Three independent values of 

Angstrom exponent (a) were calculated from the four 

channels of a sp data using the relation ex =-6.osp/6.A. where A. 

is the wavelength of light. The interpretation of ex in terms 

of aerosol size distribution was discussed by Bodhaine and 

DeLuisi (1985). Monthly geometric means of the 1990 

aerosol data are listed in Table 5.1. A graphical presentation 

of the monthly geometric means of the entire data record for 

the four stations is shown in Figure 5.2. 

The BRW data in Figure 5.1 show a asp maximum of 

about 2 x lQ·S m·l during winter and spring, typical of the 

well-known arctic haLe. The BRW long-term record shown 

in Figure 5.2 clearly shows this annual cycle in asp. The 

850-nm data for BRW for January-May are omitted from 

Table 5.1 because of instrument problems that required 

deletion of much of the data. The BRW CN record shows a 

more variable semiannual cycle with a maximum that usually 

coincides with the maximum in asp and a relative maximum 

in late summer or early spring. 

The MLO asp data shown in Figure 5.1 are fairly typical 

with large values in April and May, and smaller values in fall 

and winter. Events in April and May, caused by the 

long-range transport of Asian desert dust in the upper 

troposphere to the vicinity of Hawaii, dominate the record. 

asp values have been generally higher since the installation 

of the new nephelometer in 1985 and have not reached the 

low values expected in winter. A nephelometer comparison 

experiment was performed in the spring of 1990 in order to 

determine if asp has generally increased at MLO or if 

reduced instrument sensitivity is responsible for the higher 

values (sec section 5.2.1). The MLO CN record shown in 

Figure 5.1 is fairly typical, giving an annual geometric mean 

concentration of 203 cm·3, compared with 218 cm·3 for the 

previous year. Note that all MLO aerosol data presented 

here are in the form of geometric means during 0000-0800 

HST (1000-1800 UT) in order to include data for downslope 

wind conditions only. 

34 

The SMO asp and CN data continue as in previous years 

with no significant annual cycle or long-term trend. The 

SMO 1990 annu al mean is about 1.77 x 10·5 m· 1 for asp 

(550) and about 218 cm·3 for CN concentration (compared 
I r 

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOY DEC 

1990 

AEROSOL DATA F'OR SAMOA 

i i 

gr+---l-r-+--1---+-+--+- +---1---1---l----+- + rg 

~ 

~~+.-:~-..I,-.'.-V-Lft'...Jv:ll!__;~..i,.woj__..+-:---l~~--'61.1'4-!.~~~~ ~ 3 ' j 

T-"------'--'--'----'---'-----'----'-----''---'--"'--_J_--'-T 

.. . "-I ~ I en+---l- -+---!l---+-+--+-+---l--+--1---+--+n E ~ ~ 

z z 

~N ~ 

JAN fEB MAR APR MAY JUN JUL AUG SEP OCT NOY DEC 

1990 

AEROSOL DATA FOR MAUNA LOA 

JAN f EB MAR APR MAY JUN JUL AUG SEP OCT NOY DEC 

·- - ' ~ ,d ~ - , 

II'' . ' ..... ' r ... .. 

Jb d:: ~~· ~ l I~ ~ 

~ U''i. Yi" fW1 ft w~ 1~ · vv • _IJ\, H '' 

' 

ft ,. ., I 00 

3 

M M I I E n -!---..<---1--l--l---1--+--!----<---1--+--l---l.-.+ n E ~ ~ 

z z 

~N ~ 

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOY DEC 

1990 

AEROSOL DATA FOR SOUTH POLE 

I _g_T+---l--+--l---+-+--.-+-++....-l- -+-- JG---+-1,,--1. 

~ 

~ 'i +---!...,__,.-Jl,!-'.-~-J:f<-"';;:.J~4.\ll+----10-++.h-+...;.-+--=+ r- bn 

s 's 

T-'---1---'--'---'--"'--_J_--'-----'--'--'----'--iT n n 

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOY DEC 

1990 

Fig. 5.1. Daily geometric means of asp and CN data at BRW, MLO, SMO, and SPO for 1989. Data for MLO are included only for 

0000-0800 LST. For each station, CN concentration (lower) is shown as a solid line. asp data (middle) are shown for 450 (dotted), 550 

(solid), 700 (dashed), and 850 nm (long-dashed). Angstrom exponents were calculated from 450- and 550-nm (dotted), 550- and 700-nm 

(solid), and 700- and 850-nm (dashed) asp data. 

with 1.80 X 10·5 m-t and 229 cm·3 last year), representative 

of the background marine boundary layer in that region. The 

CN data were filled with daily Po11ak counter observations 

when available. A detailed analysis of the entire SMO data 

record was presented by Bodhaine and DeLuisi [1985]. 

The SPO CN data from the TST CN counter are shown in 

Figure 5.1. These data show a strong annual cycle reaching 

a maximum exceeding 200 cm·3 in the austral summer and a 

minimum approaching 10 cm·3 in the winter; the CN data 

appear to be higher than in previous years. Shown on the 

same graph are daily means from the Pollak CN counter 

(squares). The CN data shown in Figure 5.2 were fi11ed with 

Pollak counter data when continuous data were missing. The 

asp data in Figure 5.1 generally show intermediate values in 

the austral summer, a minimum in May, and large events, 

sometimes exceeding 10·6 m·t, in late winter. These large 

aerosol events arc caused by the transport of sea salt in the 

upper troposphere from stormy regions near the Antarctic 

coast to the interior of the continent. 

The least-squares trend lines shown in Figure 5.2 were 

calculated using the common logarithms of the monthly 

means of the entire data record, and the results are given in 

Table 5.2. Similar trend lines have been calculated and 

presented in previous Summary Reports. 

35 
TABLE 5.1. Monthly Geometric Means of CN Concentration (cm·3) and <Jse (m·l) at 450, 550, 700, 

and 850 run, for BRW, MLO, SMO, and SPO, During 1990 

Jan. Feb. March April May June July Aug. Sept. Oct. Nov. Dec. 

BR\V 

CN 192 294 366 310 217 305 582 350 284 272 155 243 

Orp(450) 1.40-5 1.84-5 1.85-5 1.31-5 7.00-6 1.53-6 2.21-6 2.60-6 3.09-6 3.25-6 6.91-6 1.14-5 

Orp(550) 1.23-5 1.67-5 1.56-5 1.06-5 5.42-6 1.21-6 1.89-6 2.53-6 3.20-6 3.04-6 6.25-6 1.06-5 

o ,P(700) 8.19-6 1.11-5 9.99-6 6.52-6 3.13-6 7.63-7 1.36-6 2.20-6 2.93-6 2.47-6 4.77-6 8.29-6 

o ,P(850) 7.0 1-7 1.73-6 2.74-6 2.90-6 2.21-6 3.94-6 6.72-6 

MLO 

CN 166 238 252 207 218 173 240 221 175 230 190 155 

Orp(450) 4.57-7 9.0 1-7 1.69-6 2.96-6 3.22-6 2.89-6 1.67-6 8.59-7 9. 19-7 7. 12-7 8.65-7 6.92-7 

o,P(550) 3.38-7 6.44-7 1.22-6 2.22-6 2.62-6 2.28-6 1.21 -6 6.30-7 6.74-7 5.08-7 5.85-7 4.9 1-7 

Orp(700) 2.39-7 4.58-7 8.84-7 1.62-6 2. 11-6 1.79-6 8.73-7 4.54-7 4.58-7 3.52-7 3.86-7 3.42-7 

Orp(850) 2.96-7 6.44-7 7.83-7 1.39-6 1.92-6 1.68-6 9.93-7 5.69-7 5.04-7 4.61-7 4.66-7 4.30-7 

SMO 

CN 253 183 254 210 253 243 208 179 2 14 201 

Orp(450) 1.90-5 2.68-5 1.79-5 1.38-5 1.73-5 1.96-5 2.35-5 2.04-5 1.80-5 1.47-5 1.62-5 1.29-5 

Orp(550) 1. 82-5 2.67-5 1.79-5 1.39-5 1.70-5 1.93-5 2.32-5 2.01-5 1.71-5 1.41-5 1.62-5 1.27-5 

Orp(700) 1.82-5 2.70-5 1.80-5 1.37-5 1.65-5 1.93-5 2.31-5 2.01-5 1.64-5 1.35-5 1.60-5 1.23-5 

o,P(850) 1.94-5 2.95-5 2.27-5 1.48-5 1.94-5 2.21-5 2.59-5 2.24-5 1.85-5 1.54-5 1. 87-5 1.36-5 

SPO 

CN 234 332 180 69 34 29 23 29 68 180 236 281 

Orp(450) 2.47-7 4.12-7 2.73-7 2.34-7 2.45-7 2.56-7 2.19-7 6.56-7 4.65-7 4.66-7 5.78-7 6.80-7 

Orp(550) 1.30-7 2.33-7 1.70-7 1.47-7 1.62-7 1.90-7 1.50-7 5.04-7 3.36-7 3.26-7 3.85-7 3.89-7 

Orp(700) 5.97-8 1.03-7 8.84-8 8.48-8 8.45-8 9.83-8 8.46-8 3.3 1-7 2.27-7 1.97-7 2. 19-7 2.54 -7 

Orp(850) 3.77-8 5.3 1-8 4.87-8 6.89-8 9.23-8 9.48-8 6.55-8 2.23-7 1.54-7 1.16-7 1.22-7 1.58-7 

A compact exponen1ial format is used for cr,P such that 1.40-5 = 1.40 x 10-s. 

5.1.2. TOTAL O ZONE OBSERVATIONS 

Total ozone observations were continued throughout 1990 

at 15 of the 16 stations that comprise the U.S.A. Dobson 

spectrophotometer network (Table 5.3). Of the 15 stations, 5 

are operated by CMDL personnel, 4 are operated by the 

NWS, 2 are domestic cooperative stations, and 4 are foreign 

cooperative stations. The Dobson spectrophotometer 

operated at Florida State University, Tallahassee, Florida, 

until November 1989 is being relocated to the Municipal 

Airport in Tallahassee and will be operated by NWS staff. 

Daily 1990 total ozone amounts applicable to local noon 

for stations listed in Table 5.3 have been archived at the 

World Ozone Data Center, 4905 Dufferin Street, 

Downsview, Ontario M3H 5T4, Canada, in Ozone Data for 

the World. Table 5.4 lists the provisional mean monthly 

total ozone amounts measured at the various stations during 

1990. 

Figure 5.3 plots mean total ozone amounts measured at 

SPO during October 15-31 of 1962-1990. (Mid-October is 

when Dobson spectrophotometer total ozone observations 

first become possible each year at South Pole following the 

polar night.) Least squares linear regressions fitted to the 

data for 1962-1979 and 1979-1990 show an initial moderate 

downward trend in ozone not statistically significant at the 

36 

95% confidence level (t-statistic), followed by a large, 

statistically significant downward ozone trend during 

1979-1990 of-4.35% yr1• During October 1988, ozone at 

SPO recovered to a value comparable to October values 

observed there in 1965, 1969, 1975, and 1977. Komhyr et al. 

[1991) attributed this recovery to increased transport from 

the tropics of heat, momentum, and ozone to SPO during 

June-October 1988 following a drop in sea-surface 

temperatures in the eastern equatorial Pacific to low values 

last observed there prior to 1976. Polar vortex breakdown 

and stratospheric warming occurred 3-4 weeks earlier in 

Antarctica in 1988, compared to the time of occurrence of 

these phenomena in other recent years, thereby causing early 

disruption of heterogeneous photochemical processes that 

destroy ozone during austral springtime in the presence of 

polar stratospheric clouds. During 1989 and 1990, JuneAugust SSTs in the eastern equatorial Pacific recovered to 

above normal values. October total ozone at SPO declined 

successively during these 2 years for the first time since 

1980. 

Figure 5.4 plots provisional total ozone anomaly data (i.e., 

monthly mean ozone deviations from monthly normals) for 

SMO, MLO, as well as for the contiguous U.S.A. stations of 

Fresno, Boulder, Bismarck, and Caribou. Least square linear 

regression trend lines are fitted to the data for 1979-1990 for 
AEROSOL DATA f"OR BARROW AEROSOL DATA f"OR MAUNA LOA 

Fig. 5.2. Monthly geometric means of O',P and CN data for the entire data record. Details of the trend lines are given in Table 5.2. 

all stations except 1984-1990 for Fresno where the record is 

of shorter duration. No significant linear trends are evident 

in 12-year SMO and MLO ozone data records, and in the 

shorter (7-year) Fresno ozone data record. Significant 

downward ozone trends averaging 4.9%/decade are present, 

however, in the ozone data from Boulder, Bismarck, and 

Caribou. While the provisional data are subject to additional 

refinement, it is unlikely that the ozone trends shown in 

Figure 5.4 are in error by more than ±1 %/decade. 

5.1.3. UMKEHR OBSERVATIONS 

Umkehr observations with automated Dobson ozone 

spectrophotometers were continued during 1990 at Boulder; 

MLO; Haute Provence, France; Perth, Australia; and Lauder, 

New Zealand. Table 5.5 lists the number of Umkehr 

observations made at each station during the year, as well as 

the number that yielded useful data. Not useful Umkehr 

observations are those exhibiting excessive cloud 

interference. The relatively fewer observations made at 

Poker Flat reflect the station's high latitude location where 

wintertime observations cannot be made. 

Because of political and economic problems, Umkehr 

observations at CMDL's seventh automated Dobson station 

at Huancayo, Peru, are no longer being made. 

37 

All provisional 1990 Umkehr data have been archived at 

the WMO World Ozone Data Centre, Atmospheric 

Environment Service, Downsview, Canada, from where they 

are received by NOAA-NESDIS (and other users) for 

comparison with NOAA-11 satellite SBUV-2 ozone profile 

measurements. Umkehr layer aerosol corrections [DeLuisi, 

1989), as a function of latitude and time, are routinely 
TABLE 5.2. Least-Squares Trend Analysis of the Common 

Logarithms of the Data Shown in Figure 5.2* 

Parameter Slope Intercept S.E. Trend(% yr-1) 

BRW CN 0.0179 0.828 0.277 4.21% 

cr'P -0.00130 -5.16 0.377 -0.30% 

MLO CN -0.00820 3.09 0.119 -1.87% 

cr'P 0.0171 -7.51 0.311 4.02% 

SMO CN -0.00949 3.23 0. 109 -2. 16% 

cr,P 0.00 166 -4.96 0. 116 0.38% 

SPO CN 0.00899 0.948 0.436 2.09% 

crsp -0.00 163 -6.42 0.194 -0.37% 

*The time axes in Figure 5.2 are in fractional years, with a data point 

centered at the center of a month; e.g., Jan. 1974 = 74.042, Feb. = 74.125, etc. 

provided to NESDIS. C.L. Mateer (Scarborough, Ontario, 

Canada) is currently improving existing Umkehr observation 

reduction algorithms by incorpor ating into them improved 

ozone absorption and primary scattering coefficients. 

5.1.4. C ALIBRATION OF NOAA-CMDL DOBSON 

SPECTROPHOTOMETERS 

Because considerable effort was spent during 1990 in 

organizing, preparing for, and conducting international 

Dobson ozone spectrophotometer comparisons in Arosa, 

Switzerland, there was time to perform calibration checks on 

only three NOAA-CMDL Dobson instruments. The 

calibration level of Dobson instrument 65, used as the 

reference spectrophotomete r at the Arosa comparisons, was 

checked relative to World Primary Standard Dobson 

instrument 83, and it was found to agree with instrument 

~ SOl/TH POLE OCTOBER TOTAL OZONE 

~· .. 

5 9g 

w 

z 

0 

N 

0 

_, 

~ 

e g 

1962-1979 

-.87 .t 1.09 X/YEAR -~.35 ± 3 . 1 ~ X/YEAl! 

!! .. 60 .. ,o .. 60 ...., YEAR 

Fig. 5.3. South Pole October 15-3 1 mean total ozone amounts 

(DU) for 1962-1990. Trend lines fitted to the data are linear 

least-squares regress ions. 

83 to within 0.3%. Optical wedges of instruments 65 and 83 

were recalibrated, and instrument 83 was sent to MLO where 

special observations were conducted during June-August to 

check its calibration using the Langley method. These 

showed that the calibration level of instrument 83 was 

unchanged from that determined for it at MLO in 1989, to 

within several tenths of a percent experimental error. 

Enroute to the Dobson instrument comparisons in Arosa, a 

detour was made to Haute Provence Observatory in France, 

to recalibrate NOAA-CMDL automated Dobson spectrophotometer 85 which had last been calibrated in 1986. No 

significant change with time was detected in the calibration 

o f instrument 85 whose total ozone values agreed with those 

of secondary standard Dobson instrument 65 in the me an to 

0.2%. 

TABLE 5.3. U.S. Dobson Ozone Spectrophotometer Station Network for 1990 

Station Period of Record Instrument No. Agency 

Bismarck, ND Jan. I, 1963-present 33 NOAA 

Caribou, ME Jan. I, 1963-present 34 NOAA 

Wallops Is., VA July 1, 1967-present 38 NOAA; NASA 

SMO Dec. 19, 1975-present 42 NOAA 

Tallahassee, FL May 2, 1964-Nov. 30, 1989 58 NOAA; Florida State University 

Boulder, CO Sept. 1 , 1966-present 61 NOAA 

Poker Flat, AK March 6, 1984-present 63 NOAA; University of Alaska 

Lauder, New Zealand Jan. 29, 1987-present 72 NOAA; DSIR 

MLO Jan. 2, 1964-present 76 NOAA 

Nashville, TN Jan. 2, 1963-present 79 NOAA 

Perth, Australia July 30, 1984-present 81 NOAA; Australian Bureau Meteorology 

SPO Nov. 17, 1961 -present 82 NOAA 

Haute Provence, France Sept. 2, 1983-present 85 NOAA; CNRS 

Huancayo, Peru Feb. 14, 1964-present 87 NOAA; IGP 

BRW June 6, I 986-present 91 NOAA 

Fresno, CA June 22, 1983-present 94 NOAA 

38 
TABLE 5.4. Provisional 1990 Monthly Mean Total Ozone Amounts (m-atm-cm) 

Station Jan. Feb. March April May 

Bismarck, ND 331 374 362 356 353 

Caribou, ME 335 393 394 38 1 382 

Wallops Is., VA 298 315 337 373 357 

SMO 261 256 254 250 252 

Tallahassee, FL 

Boulder, CO 322 338 338 345 338 

Poker Flat, AK 385 384 370 

Lauder, New Zealand 288 267 275 281 300 

MLO 250 250 265 278 286 

Nashville, TN 295 304 329 351 339 

Perth, Australia 280 276 271 277 280 

SPO 272 291 198 243 

Haute Provence, France 325 290 333 380 359 

Huancayo, Peru 258 251 253 251 245 

BRW 378 405 379 

Fresno, CA 319 337 332 344 346 

TABLE 5.5. Umkehr Observations Frequency 

During 1990 

Station Total No. Total No. 

Station Coordinates Obs. Made Useful Obs. 

Boulder 4()<>N, 105°W 508 205 

Haute Provence 43°N, 6°E 459 246 

Lauder 45°S, 170°E 620 151 

MLO 2()<>N, 156°W 599 385 

Perth 32°S, l 16°E 504 284 

Poker Flat 65°N, 147°W 379 90 

While at Haute Provence, France, French Dobson spectrophotometer 49 was calibrated. It was found to measure 

ozone too low by 1.89%. 

5.1.5. INTERNATIONAL CALIBRATION OF DOBSON 

l l\STRUMENTS IN AROSA 

International Dobson spectrophotometer comparisons 

were conducted by NOAA-CMDL ozone project scientists at 

Arosa, Switzerland, July 21-August 9, 1990, under auspices 

of the WMO. Seventeen countries including the U.S.A. 

participated with 18 instruments. Table 5.6 lists the 

participants and instruments. Results of the comparisons are 

summarized in Table 5.7 

Of the 17 instruments calibrated in Arosa relative to 

U.S.A. secondary standard Dobson instrument 65, 15 had 

previous calibrations traceable to CMDL's World Primary 

Standard Dobson Spectrophotometer 83. Calibration errors 

were determined to be less than 1 % for 12 of these 15 

instruments. Of the three instruments with larger calibration 

errors, one (Iceland's instrument 50) had not been calibrated 

since 1977. 

June July Aug. Sept. Oct. Nov. Dec. 

328 313 304 288 299 286 334 

350 339 325 317 287 289 321 

342 326 314 285 286 282 

244 241 252 254 258 257 262 

305 304 299 283 286 274 313 

344 317 299 322 321 

303 324 339 353 343 321 301 

279 276 276 270 264 260 257 

320 322 318 311 287 285 293 

277 298 304 320 329 307 295 

261 248 233 208 151 186 273 

338 335 326 318 287 304 312 

255 252 253 264 265 263 256 

355 315 294 344 

320 311 311 304 297 280 307 

Two instruments had not been calibrated previously by 

CMDL. They were instruments 15 (Switzerland) and 118 

(Greece), with calibration errors of -4.96% and -5.94%. 

As indicated in Table 5.7, additional work was performed 

on 13 instruments to recalibrate optical wedges, or to correct 

optical or electronic problems. 

Comparison Umkehr observations were made one morning 

during the Arnsa instrument comparisons with 15 instruments. 

Observational data from C-wavelength observations were 

processed by the standard Umkehr technique [Mateer and 

Dutsch, 1964], and Umkehr layer mean ozone amounts were 

computed. Figure 5.5 plots the layer mean ozone amount 

differences in percent from Umkehr layer ozone values 

measured with secondary standard Dobson instrument 65. A 

maximum difference of 9% is evident for Umkehr layer 9. In 

an attempt to determine a possible cause of the differences, 

Umkehr layer 9 differences were plotted as a function of the 

ozone measurement residual (Figure 5.6), a statistical measure 

of observation quality derived during data processing. Note 

the correlation (Figure 5.6) between the residuals and percent 

ozone differences, indicating that instruments with low ozone 

measurement residuals yielded Umkehr layer ozone values 

that agreed more closely with Dobson instrument 65 values 

than did instruments having higher measurement residuals. 

5.1.6. VALIDATION OF TOMS AND SBUV SATELLITE 

INSTRUMENT OZONE DATA 

NOAA-CMDL World Primary Standard Dobson 

spectrophotometer 83 was operated in June-August 1990 at 

MLO in an ongoing program to assess the quality of total 

ozone data obtained with the TOMS and SBUV 

spectrometers aboard the Nimbus 7 satellite. Relative to 

Dobson instrument 83, whose long-term ozone measurement 

precision has been maintained at ±0.5% [Komhyr et al., 

1989], the calibration of the TOMS instrument has continued 

to drift (Figure 5.7a), at a rate now approaching 0.9% yr1• 

39 
MAl.JNA LOA 20N 156W 

~ I O, TilF..1'1>: -0.0ll :!: 0.160 ~rr4 

0 

~-!---~~~~~~~~~~~~~.--~~~~-..,.~~~~ 

I 

$-i-~...._~..._~..__~..__~~~---~~~~~~~~~~-1-

FllESNO 37N l20W 

0 

N 

0 

$-i-~...._~..._ ...._~..__~~~---~~~~~~~~~~-1-

BOU.DER -4()N 'l>':N( 

of1'1T\l~~~-,.#4~Ll 

~ 

0 

r-l--~~~~ ~~~~.--~.-1--~~-..,.~~~~~~~-+-

-+-~...._~..._~..__~..__~~~---~~~~~~~~~~~ 

BISMARCX .QN lOIW 

$+-~--'+~-'-~..._~...._~..__~~~---~~~~~~~~-+-

CAR.SOU .QN 68W 

o, TRU-1>: 

$ I I 

, 1979 l9 3 1987 1991 

Fig. 5.4. Provisional total ozone anomaly data derived from 

Dobson spectrophotometer observations. Least squares linear 

regression trend lines are fitted to 12 years of data for all stations 

except 7 years of data for Fresno. Indicated uncenainties in the 

trends arc 95% confidence limits (student's t-statistic). 

Dobson instrument 83 has been used since the mid-1970's 

to calibrate Dobson instruments of the global Dobson 

spectrophotometer station network. While in the past the 

10 

9 

8 

L 7 

Q) 

>-

0 6 

_J 

L 5 

..c 

Q) - ..Y. 4 

E - :::> 3 

2 

-

I 

-1 0 -5 

Percent 

l 

I 

-

I 

l 

0 

03 

I 

5 10 

Difference 

Fig. 5.5. Differences in percent of mean Umkehr layer ozone 

derived from measurements with 15 Dobson spectrophotometers 

from Umkehr layer ozone measured with secondary standard 

Dobson instrument 65. 

40 

<I> 

u 

c 

<I> 

~ 20 

--

0 

ti) 10 

0 

-

~ 0 

u 

I... 

* * 

* 

* 

* 

** * 

Umkehr Loyer 9 

CL-10,..+-~~~~~~~~~~~-..,.~~~~~~.--~~ <I> * 

0.15 0.20 0.25 0.30 0.35 

Residual 

0.45 0.50 

Fig. 5.6. Variation of Umkehr layer 9 ozone differences in percent 

for 14 Dobson instruments from secondary standard Dobson 

instrument no. 65 Umkehr layer 9 value as a function of observation 

quality (residual). The lowest value residual shown is that obtained 

with instrument 65. 
TABLE 5.6. Arosa Dobson Instrument 

Comparison Participants 

Country Dobson Instrument Participants 

United States 65 W. Komhyr, R. Grass, 

R. Evans 

Portugal 13 D. Henriques, 

J. Cacho 

Norway 14 K. Henriksen 

Switzerland 15 K. Aeshbacher 

Belgium 40 D. De Muer, 

H. De Bacher 

United Kingdom 41 A. Lapworth 

France 49 J. de La Noe 

Iceland 50 8. Thorkelsson 

German Democratic 64 U. Feister, P. 

Republic Plessing 

Czechoslovakia 74 K. Vanicek 

Poland 84 M. Degorska, 

B. Rajewska-Wiech 

Denmark 92 P. Eriksen 

Switzerland 101 J. Staehelin, 

8. Hogger 

Federal Republic 104 U. Koh ler, 

Germany R. Hartmannsgruber 

U.S.S.R. 107 V. Dorokhov 

Hungary 110 F. Miskolczi, Z. Nagy, 

G. Luska 

Greece 118 D. Asimakopoulos, 

C. Varotsos 

Spain 120 J. Cacho, A. Diaz 

Romania 121 M. Frimescu 

TOMS and SBUV data have been corrected by normalization 

to Dobson spectrophotometer total ozone values [World 

Meteorological Organization, 1988], a pair wavelength justification technique has been recently developed by NASA 

scientists as an independent means of correcting the satellite 

data. Data thus corrected are referred to as Version 6 data. 

As shown in Figure 5.7b [see also McPeters and Komhyr, 

1991), the agreement between the corrected TOMS data and 

Dobson instrument 83 data is now highly satisfactory. 

To investigate the possibility of instrument stray light 

affecting the MLO Dobson instrument 83 observations that 

involve A-wavelength (305.5/325.0-nm) observations, an 

analysis was conducted in 1990 using longer, C-wavelength 

(311.5/332.4-nm) observations made at MLO since 1979. 

Stray light effects at the longer wavelengths are negligible. 

As shown in Figure. 5.7c relative to TOMS data, 

observations with Dobson instrument 83 on AD and C 

wavelengths yield highly similar results, lending credance to 

the validity of the MLO Dobson instrument 83 and the 

TOMS and SBUV instrument comparisons. 

5.1.7. TROPOSPHERIC OZONE 

Surface ozone measurements continued at the four CMDL 

observatories as well as the AEROCE sites at Bermuda, 

Barbados, and Mace Head, Ireland. In addition, observations 

started in July al Niwol Ridge in conjunction with the CFC 

(a) 

-·':-~ ................... ~_._~_,_~....._~,__._,~-L--'-J-~_J_~.L,........J 

w 

ffi 4 

"" 

~ 3 

"" ..... 

Cl 2 

~ 

i:'i 1 

el 

n ro ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ 

YEAR 

vs 183 

... - - - .. " - - '"6- - - • - - ._ .. - .. a - - -...... - - & .. 

--· vs 39 Dobson slalions 

TOMS Version 6 c:i..01--------------------- ---< 

(b) -1 1--.__ .......... _ _._ _ _.__.....__.___. _ _._ _ _,_ _ _.___..__~ 

79 80 a1 82 83 84 85 86 87 88 89 90 91 

YEAR 

(c) 

(c) 

80 81 82 83 84 85 86 87 88 89 

YEAR 

Fig. 5.7. (a) TOMS and SBUV total ozone data compared with 

Dobson instrument 83 total ozone data at MLO and total ozone data 

from 39 select Dobson instrument stations showing calibration drift 

with time of the satellite instruments due to diffu ser plate degradation. (b) TOMS version 6 total ozone data corrected by means of a 

pair-wavelength justification technique, compared with Dobson 

instrument 83 data and data from 39 select Dobson instrument 

station. (c) Corrected TOMS total ozone data, compared with 

Dobson instrument 83 data derived from observation on AD as well 

as C wavelengths. 

measurements of the NOAH Group. Monthly mean ozone 

mixing ratios for 1990 at each site are given in Table 5.8. At 

SPO there has been a long-term decrease in the surface 

ozone concentration during the spring and summer [Schnell 

el al., 1991]. Figure 5.8 shows the long-term monthly means 

(1975-1989) compared with the averages over the 5 years 

(1985-1989). The percentage departures of the 5-year mean 

from the long-term mean show decreases of 5% or more 

41 
TABLE 5.7. Results of The 1990 Arosa International Comparisons of Dobson Ozone Spectrophotometers 

Initial Initial Final Final 

Inst. Last Ca lib. Error Ca lib. Error Wedge Optics Electronics 

No. Country Calib. Error(%) Range(%) Error(%) Range(%) Ca lib. Adjjustment Adjustment 

13 Portugal 1987 0.28 1.40 -0.16 1.32 

14 Norway 1977 -0.99 2.85 -0. 19 1.69 Yes 

15 Switzerland • -4.96 2.85 0.82 5.95* Yes 

40 Belgium 1986 -0.60 1.68 -0. 15 1.33 

41 United Kingdom 1985 0.59 0.39 0.15 1.03 

50 Iceland 1977 -3.16 0.50 0.05 0.32 Yes Yes* 

64 GDR 1977 0.22 0.52 -0.09 0.78 

74 Czechoslovakia 1986 -0.66 1.01 -0.07 0.75 Yes 

84 Poland 1986 0.35 1.15 -0.05 0.85 Yes Yes 

92 Denmark 1986 -0.50 1.10 -0.05 0.75 Yes 

101 Switzerland 1986 0.37 0.51 0.09 1.16 

104 FRG 1986 -2.40 1.19 -0.04 1.04 Yes Yesf 

107 USSR 1988 -0.95 0.67 0.00 0.60 Yes .. 11 0 Hungary 1988 0.93 1.1 2 -0.24 1.95 Yes 

118 Greece .5,94t 11.7 1 0.03 0.78 Yes Yes 

120 Spain 1989 -1.92 1.33 0.20 1.30 Yes 

121 Ru mania 1988 -0.06 0.64 0.04 1.54 Yes 

65 USA 1990 

Observations were made over the μ-range 1.15-3.2. 

•Better calibration not possible, as instrument needs optical alignment. 

tcalibration error in the observing interval 1.15 < μ < 1.5 was -2.27%. 

*New mirrors installed. 

f Phototube adjusted, mirrors adjusted, and rocking cover problem corrected. 0

'New mirror Ml installed. 

TABLE 5 .8. Monthly Mean Surface Ozone Concentrations in PPB During 1990 

Jan. Feb. Mar. April May 

BRW 32.5 29.1 27. l 19.6 24.6 

Mace Head 31.7 34.3 35.6 40.4 41.1 

NWR 

Bermuda 22.3 35.5 41.1 43.5 39.9 

MLO 37.2 37.6 47.6 47.6 49.9 

Barbados 29.4 26.7 24.6 19.9 19.8 

SMO I I.I 10.9 I I.I 10.6 16.4 

SPO 20.4 20.1 23.2 24.7 27.9 

during the spring and summer. The December-I anuaryFebruary trends are significant at the 95% confidence level. 

These data suggest that this decrease is associated with the 

mech anisms responsible for producing the season al minimum. 

Much of the southern hemisphere is thought to have low 

NO. concentrations. Under such conditions, ozone will be 

lost in the lower troposphere by the action of UV radiation 

penetrating to the surface [Crutzen, 1989]. Such losses will 

be largest during the summer and at latitudes where sunlight 

is most abundant. At SPO the seasonal cycle appears to be 

driven by decreasing ozone concentrations on the periphery 

of Antarctica that are transported poleward during the spring 

June July Aug. Sept. Oct. Nov. Dec. 

23.5 2 1.1 25.6 32.3 33.0 34.4 32.7 

34.7 32.7 29.3 36.1 33.6 31.2 33.2 

46.9 46.7 44.3 43.6 41.8 42.1 

25.0 20.2 25.9 30.3 31.2 38.2 36.4 

42.6 32.5 31.5 29. l 35.0 28.4 38.5 

18.5 18.0 16.2 16.5 19.1 22.7 28.4 

15.8 19.6 19.0 13.2 12.4 12.9 12.9 

31.3 32.4 29.9 28.2 27.1 27.6 24.0 

and summer [Schnell et al., 1991]. Both the degree of ozone 

destruction and the transport into the Pole have probably 

contributed to the changes seen in Figure 5.8. The decrease 

in stratospheric ozone during the spring over Antarctica has 

been dramatic since the early 1980s. This loss has extended 

into midlatitudes of the southern hemisphere [Stolarski et al., 

1989]. The reduction of overhead column ozone amounts 

h as allowed greater penetration of UV radiation to the 

surface with the resulting greater tropospheric ozone loss 

[Schnell et al., 1991]. 

It has also been found that during the summer (JanuaryFebruary) that there has been an increase at the South Pole in 

cloudiness that parallels the decline in surface ozone. Since 

42 
.... __ _ 

--. 

~,,. -- -1~\· I~ 

~o >-:~-:::::----:-~--~~~~~~~~~~~~~~--1 .,., rro !Wt APR Mt ""4 .AA.. AUG SCP OC1 ''°" occ l'IONTH 

Fig. 5.8. Lower curves. Mullti-year averages of surface ozone 

mtxmg ratio at SPO for the periods 1975-1989 and 1985- 1989. 

Upper curve. Percent difference between the two periods. 

the primary source of the cloudiness is the transport of moist 

air from the edges of Antarctica, the enhanced transport of 

ozone-poor air to SPO has also been an important contributor 

to the long-term decline [Schnell et al., 1991]. 

At Bermuda there is a springtime peak in the seasonal 

cycle with lower summertime values [Komhyr and Rosson, 

1990]. The spring peak results from strong pulses of ozone 

advected to Bermuda during this time of year. This behavior 

is illustrated in Figure 5.9 which shows the hourly concentrations during May 1990. The high values (over -45 ppb) are 

associated with flow from the midtroposphere over North 

America. The low values occur under weak flow conditions 

with the air often originating south of Bermuda and generally 

<Do 

Cl.."' 

Cl.. 

_.,, 

o"' 

:r: :?l 

a: "' (..!) ... 

~o x ... 

1= ~ 

~g ::> 

cSlG 

> 

w~ 

z 

o.,., 

NO 

"' 

5 10 15 20 25 30 

ORY 

Fig. 5.9. Hourly ozone concentrations (ppb) at Bermuda for May 

1990. 

confined to lower altitudes. This can be seen dramatically in 

the strong event beginning on May 19 where ozone values go 

from less than 15 ppb to over 65 ppb in a few hours. The 

isentropic back trajectories from Bermuda for 00 and 12 UTC 

on May 19 (Figure 5.lOa and b) show a pronounced change 

with low-level flow from south of Bermuda shifting to 

midtropospheric flow that traveled from western North 

America in the 10-day period represented. During the summer 

when the Bermuda anticyclone dominates, the high ozone 

events virtually cease, leading to gradually decreasing ozone 

concentrations through the summer. 

5.1.8. OZONESONDE OBSERVATIONS 

A digital ozonesonde system for obtaining vertical 

profiles of ozone was installed at SPO in November 1990. 

This system provides an automated, low initial cost method 

for obtaining ozone vertical profiles from balloonborne 

ozonesondes. The balloon flight package consists of an ECC 

ozonesonde mated to a Vaisala 403MHz radiosonde through 

a microprocessor-based interface. The three components of 

the system are purchased commercially and integrated into a 

flight package. This integration was carried out under a 

contract with the University of Wyoming. In addition, each 

of the air pumps on the ozonesonde was individually 

calibrated to determine the pumping efficiency loss at 

altitudes above 15 km (100 mb). 

The operation of the ozonesonde sensor has been 

described previously in several publications [Komhyr, 1969, 

1986]. The microprocessor-based interface (TMAX) 

measures six frequencies of the Vaisala RS-80 radiosonde 

along with the current output of the ECC sensor and the 

temperature of the ozonesonde pump. These parameters are 

formatted into a hexadecimal, ASCII serial data stream every 

6 seconds. This data stream is converted to an audio 

frequency shift keyed (AFSK) signal which modulates the 

Vaisala transmitter in place of its standard frequency output. 

The ground station for the system consists of an FM radio 

receiver capable of obtaining a signal at the 403 MHz carrier 

transmitting frequency of the radiosonde, an antenna with a 

preamplifier, a modem, and a lap-top computer. A printer 

and a cassette tape recorder for recording the audio output of 

the receiver are optional equipment used to provide backup 

for the data acquisition. 

The computer software package developed by the University of Wyoming records the telemetered data, processes the 

raw data, and provides for tabular and graphical presentation 

(Figure 5.11) of the information. The digital form of the data 

allows for rapid processing and transmittal of the complete 

profile information for plarming and research purposes. 

The austral spring of 1990 marked the second consecutive 

year of very strong depletion over Antarctica of the 

stratospheric ozone layer. Since the early 1980s there has 

been a pattern of alternating years of larger and smaller 

ozone amounts in the springtime stratosphere with smaller 

amounts in 1985, 1987, and 1989. In 1990 values in the 

stratosphere approached the very low values seen in 1987 

and 1989. In addition, low amounts persisted into December 

43 
G' 

0.. 

400 

.t: 

" .. 600 :I 

.. .. 

" .. 

0. 600 

(a) 12o·w 

50°N 

30°N 

l0°N 

~ 400 II 

0. 

=. 

" .. 600 :I 

.. .. 

"' .. 

a. 600 

(b) 12o·w 

50°N 

30°N 

10°N 

9o•w 

~ 

60°w 3o•w 

lday 19 90 Bermuda JOOK 

00 UTC 

9o•w 60"W Jo•w 

~ 

May 19 90 Berm uda 305K 

12 UTC 

o· 

o· 

Fig. 5. to. Iseniropic back trajectories to Bennuda for May 19, 

I 990 (a) 00 UTC and (b) 12 UTC. 

at SPO. These year-to-year differences in the degree of 

ozone depletion appear to be related to variations in 

circulation patterns associate with the changes in SST and 

the tropical stratospheric quasibiennial wind oscillation 

[Angell, 1990; Komhyr et al., 1991). 

A limited program of ozonesonde measurements was done 

in Hilo, Hawaii, with approximately three soundings per 

month. Ozonesonde measurements were discontinued at 

SMO after January 1990, and only occasional training flights 

were made in Boulder during the year. 

0 0 

0 

0 

ALTITUDE (km) N 

0 VI 0 

.p. 

0 

"' 

-0 

)> lJ1 

:::Uo 

-i 

}> 

r 

-0 - :::Uo 

rrio 

t/) 

t/) 

c 

:::u 

rri-lJ1 

,-_ O 

:::> 

CJ 

.._,, 

N 

8-0 

0 

0 

\ . . j'~ .. \ 

~ I / 

i 

/ 

/ I 

I 

I 

I 

( . : ~ 

.. ,.. ' 

·' 

0 0 0 

APPROXIMATE PRESSURE (mb) 

Fig. 5. I 1. Profile of ozone pania\ pressure (nb} at SPO obtained 

from the digital ozonesonde system. 

5.1.9. STRATOSPHERIC WATER VAPOR 

Monthly balloon soundings of the water vapor content of 

the upper troposphere and stratosphere continued in Boulder . 

This data set now includes the 10-year period 1981-1990. 

The mixing ratio from each sounding at three stratospheric 

levels (25 mb, 50 mb, 80 mb) is shown in Figure 5.12. The 

greater variability al 80 mb is associated with the seasonal 

change in the local tropopause height. The lowest mixing 

ratios (<3 ppmv) are associated with the appearance of 

water-vapor concentrations in the late winter and spring 

reflec ting the drying of the stratosphere that talces place in 

the western tropical Pacific. At 50 mb the variability is 

relatively low and a possible long-term increase may be 

talcing place. This may, however, reflect the low values 

measured early in the program. At the highest level shown 

(25 mb) a trend is not apparent. The mean value (solid line) 

shows a noticeable increase with altitude. 

44 

5.1.10. LONG-RANGE TRANSPORT OF TRACE GASES 

Isobaric and isentropic trajectory models have been 

developed and used within CMDL over the past decade. The 

isobaric model is documented by Harris (1982), while the 

methodology for isentropic trajectories is described in Harris 

and Bodhaine [1983]. In addition, most Summary Reports 

contain an article describing the latest developments in and 

studies using atmospheric trajectories. 

This year the isentropic model was modified to accept the 

consolidated GRIB data set supplied by ECMWF. This data 

set consists of global meteorological data at 14 mandatory 

levels from 1000 to 10 hPa. Atmospheric transport studies 
;~~~~~~~~~~~~~~~~~~~~~~~ 

r: 

"-"-

a 

..... 

:::: ~ 

x 

r: 

, ... .,. .. ; .. ,.. \ :· .. •t.~ 

.. . . .... ,., .. · . ... 

15 cb 

llO 81 82 83 8• 85 86 87 88 89 90 91 92 

YEAR 

SO ob 

llO 81 82 BJ 8< 85 86 87 88 89 90 91 92 

YEAR 

;~~~~~~~~~~~~~~~~~~~~~~~ 

r: 

Q._ 

Q._ 

-~ 

0 

t- • • " 

~ ~ 1----~·· ........ ~:·~"·-'~\.~~ -.. : ,,;•-7,,..; .;.,.. ... .',. .. -..... -.. ,., (.!) .,-•• It t t I I ~ fl I t 

~" .. ·.. . ... >< 

;: 00 nb 

llO 81 82 83 81 85 86 87 88 89 90 91 92 

YEAR 

Fig. 5.12. Water vapor volume mixing ratios (ppm) at three levels 

in the stratosphere over Boulder. Each circle is the mixing ratio at 

the given level from a balloon descent profile. Note the scale 

difference at 80 mb. 

relating to stratospheric ozone depletion arc now possible with 

these analyses extending into the stratosphere. The domain of 

the isentropic model was expanded by using extended 

memory, so that cases with flow from outside the polar vortex 

can be diagnosed. Temperature and illumination along the 

trajectory path were features added to aid in determining 

conditions favorable to chemical ozone depletion. 

Stratospheric ozone vanattons above Heiss Island 

(80SN, 57 .S'E) were investigated in collaboration with 

scientists from the U.S.S.R. and the University of 

Milwaukee-Wisconsin. Figure 5.13 is a time-height 

cross-section of temperature ('C) for Heiss Island during 

winter 1988-1989. At around 20 km in the lower stratosphere, very low temperatures, often below -80'C, were 

measured in January and early February. During the last half 

of February, a pronounced warming of at least 40' occurred 

at this level. Figure 5.14 is a time-height cross section of 

ozone concentration (nb) showing a corresponding change in 

ozone over Heiss Island. At 20 km the ozone concentration 

was low and steady at about 140 nb until the warming. By 

February 20, ozone concentration at this level had surpassed 

250 nb. 

Backward isentropic trajectories for Heiss Island show 

that before the major warming, flow was confined to a tight 

path within the vortex and wind speeds were low (i.e. , 

February 2, Figure 5.15). Trajectories for February 20 

(Figure 5.16) confirm that the vortex had eroded. It appears 

60 

so 

~o 

~ 

"' so 

20 

10 

~~;· 21 

-?0~.70 G ~"'° ~-.0 

20 

DEC 

10 20 

)Alf 

10 20 

P'EB 

Fig. 5.13. Time-height cross-section of temperature ('C) over 

Heiss Island during winter 1988-1989. 

that strong southerly flow transported the warmer, ozonerich air from lower latitudes. This is an example where 

atmospheric dynamics appear to have played a major role in 

determining ozone concentration. 

Ozone variations were also investigated over Kiruna, 

Sweden (68.0'N, 21.0'E) during winter 1989-1990 [Hofmann 

and Deshler, 1991]. Isentropic trajectories for the lower 

stratosphere (500 K) were calculated. Figure 5.17 shows 

ozone profiles for several balloon flights. A "notched" area 

from 20-25 km is suggestive of the beginnings of ozone 

chemical destruction. Figure 5.18 shows 550 K isentropic 

trajectories arriving above Kiruna on January 26, 1990. 

Flow appears to be confined within an elliptical vortex. The 

temperature history along the trajectories (lower plot, Figure 

5.18) confirms that during the day prior to arrival, temperatures were below -80'C, which is required for the formation 

of polar stratospheric clouds. In addition, symbols plotted 

along the temperature plot indicate that the air parcel was 

illuminated. Sunlight is necessary to free Cl before 

destruction of ozone can occur. This example supports the 

possibility of ozone chemical depletion. 

45 

~ 20 

N 

10 

10 20 

JAN 

10 

FEB 

20 

Fig. 5.14. Time-height cross-section of ozone concentration (nb) 

over Heiss Island, January and February 1989. 
·-.. 

so• N, ··· ... 

120° E 

140 

·· .. 

1eo0 E 

' 100° w 

1ao0 w ' 

140° w 160° w 

Fig. 5.15. Heiss Island trajectories (500 K) arriving February 2, 

1989: A = 0000 UT, B = 1200 UT. 

Isobaric back trajectories and radon data were used to 

determine air parcel origins for a study of CH4 variability at 

MLO. Scientists from CMDL's Carbon Cycle Group, 

CSIRO, and ANSTO were co-investigators. Six common 

now pauems were determined for the 3-year period July 

1987-June 1990 using the cluster analysis method described 

in llarris and Kahl (1990]. Only 1200 UT trajectories were 

considered to insure free tropospheric sampling conditions 

· .. 

······ ... 

70°.N .. '.. 

so• N, · · .......... . 

120° E 

' 140 100° w 

160° E ·, 

20° w 

' 1ao0 w 

160° w 

' 140° w 

Fig. 5.16. Heiss Island trajectories (500 K) arriving February 20, 

1989: A = 0000 UT, B = 1200 UT. 

ALTITUDE (km) N N (.,> (.,> .f>. 

0 ti\ 0 ti\ 0 ti\ 0 ti\ 0 

0 

0 "' ~ 

s:: 

x 

-N 

z 

C) 

::u (.,> 

)> 

: I -l 

0 

,-..._ .f>. 

NNNN \J 

\J CJ\U\~N 

3 c_ c_ c_ <- )> )> )> )> 

< ti\ zzzz '--" c.o c.o c.o c.o 0000 

en ~ 

0 0 0 

APPROXIMATE PRESSURE (hPo ) 

Fig. 5.17. Ozone mixing ratio p rofiles for four balloon flights from 

January 22-26, 1990 over Kiruna , Sweden. 

during downslope flow. Figure 5.19 shows the six cluster 

means that represent groups of similar l 0-day back trajectories. The percent of trajectories falling in each cluster 

appears with the cluster number (1-6) 10 days upwind of 

MLO. To explore the hypothesis that flow patterns (and 

hence possible source/sink areas) directly affect the CH4 

te · w 1•0~ w ~~ 

~o

u10' w 

tj .· . . .... DASuo-oz H - In 

~~ •• .•• ..... ·· -- ..••.... we··· ··, •. ·· . 

:::.: 

wg 

.... ' ... --.-. - -,.-. --,.----..---.--.-.--.-7--,.-. --,....-~.~ 

DAYS FROM KIRUNA - SYMBOL DENOTES ILLUMINATION (3-H) 

Fig. 5.18. Kiruna isentropic trajeclories (550 K) arriving January 26, 

1990: A= 0000 UT, B = 1200 UT. The lower plot depicts temperature ('C) along the trajectories. Symbols (o for 0000 UT, x for 1200 

UT) denote illumination of the air parcel during lhe 3-hour time step. 

46 
SO'N ·--· -

30"N 

IO'N 

180'W IOO'W 

Fig. 5.19. Atmospheric transport regimes for MLO, depicted by 

cluster mean back trajectories at 700 hPa for the period July 

1987-June 1990. Plus signs indicate I-day upwind intervals. The 

numbers 10 days upwind of MLO show the percent of complete 

trajectories occurring in that cluster (top) and an arbitrary cluster 

number used for identification (bonom). 

mixing ratio at MLO, an hourly average (1100-1200 UT) 

detrended CH4 value was paired with each trajectory. Figure 

5.20 shows the distribution of detrended CH4 according to 

the six transporl clusters. Note that cluster 3 has a median 

CH4 value (1699.5 ppbv) that is 17.2 ppbv higher than that 

of cluster 5 (1 682.3 ppbv). Cluster 3 corresponds to strong 

westerly flow from Asia where rice cultivation, ruminants, 

and other CH4 sources are concentrated [Fung et al., 1991]. 

Cluster 5 trajectories have 10-day origins mostly in tropical 

regions of the eastern Pacific. This area is postulated as a 

> 

CD 

\ 720 

17 10 

0. 1700 

0. 

I 

... 1690 

::i: 

u 

\680 

1670 

700 hPa 

N=20 1 104 72 117 237 

1660 -'----f---+-- t---+----r---r--~ 

2 3 ~ 5 6 

CLUSTER NUMBER 

Fig. 5.20. _Distribution of detrended CH4 mixing ratio (ppbv) according 

to transport cluster. The asterisk is the median; the line across the box is 

the mean; the bottom and top of the box are the 25th and 75th 

percentiles; the ends of the whiskers are the 5th and 95th percentiles 

The cluster number refers to the transport regimes shown in Figure 5.19. 

net sink for CH4 because of the presence of OH radicals 

[Spivakovsky et al., 1990] and the absence of CH4 sources. 

Two factors besides direct transport that could contribute 

significantly to the difference in CH4 distribution between 

clusters 3 and 5 are transport across the CH4 latitudinal 

gradient and seasonality of flow patterns. 

Case studies compared individual trajectories, radon data 

(a tracer of continental air), and the MLO CH4 record. 

Examination of synoptic scale events in the CH4 data 

revealed that transport from the proposed source area was 

reflected in CH4 values up to 50 ppbv higher than CH4 

values during flow from the Pacific sink area. Trajectories 

also provided evidence that transport affects the CH4 mixing 

ratio on the seasonal time scale. Figure 5.21 shows cluster 

means describing MLO transport patterns for (a) February 

and (b) August. These plots are excerpted from the 8-year 

climatology of Harr is and Kahl [ 1990]. During winter the 

changing synoptic situation results in alternation among very 

different flow types at MLO: strong westerlies, anticyclonic 

curving flows arriving from the northeast, easterly trades 

(including southeast flow), and sometimes, southwest flow as 

seen in a case study for February 1990 (not shown). In 

addition, the region of highest OH concentration migrates to 

the south [Spivakovsky et al., 1990], so that MLO is situated 

on the northern edge of the strong sink area. The changing 

flow patterns, combined with the influences of the source and 

sink regions, result in a more variable CH4 record in winter 

than in summer (especially July and August). 

Fig. 5.21. Atmospheric transport regimes for MLO for a) February 

and b) August, depicted by cluster-mean back trajectories at 700 

hPa for the period 1981 -1988. Plus signs indicate I-day upwind 

intervals. 

47 
Figure 5.2lb indicates air parcel origins in lhe sink region 

and no contact wilh Asia at a time when CH4 reaches lhe 

lowest levels of lhe year. Variability in lhe CH4 record is 

reduced as the flow patterns in summer become more 

homogeneous and lhe region of peak OH concentration 

moves northward, so lhat MLO is centrally located with 

respect to the methane sink region. A publication detailing 

these results is planned for 1991. 

5.2. SPECIAL PROJECTS 

5.2.1. NEPHELOMETERCOMPARISON ATMLO 

Introduction 

A four-wavelength (4-A.) nephelometer, model 1559B 

manufactured by MRI, was installed at MLO in January 

1974. This instrument operated admirably until the 

beginning of 1981 when it was sent in for repairs. Because 

of continuing problems for the next 3 years, lhe instrument 

was returned to Boulder to be upgraded wilh electronics to 

match that used in lhe nephelometers at the olher three 

baseline stations. The instrument was put back into 

operation at MLO in early 1985. 

The new electronics allowed better control over lhe 

operation of the instrument because it allowed the operator 

control over instrument cycle times, averaging times, and 

calibration procedures. However, the instrument retained the 

same optics. The operation of the original instrument was 

described in the Summary Report for 1974 [Miller, 1975] and 

the operation of the new instrument was described by 

Bodhaine (1982]. An important difference between the two 

designs is that the original instrument used a geometric 

averaging technique, and the new design uses an arilhmetic 

averaging process. Because long averaging times (about 1 

hour) are necessary to recover an inherently noisy signal 

during clean conditions, it is expected that the geometric 

mean may be significantly lower than the arithmetic mean. 

An additional concern has been that, because of the diurnal 

effects at MLO, lhe instrument may not fully settle to the 

clean background values during the night. 

Examination of the MLO asp record in Figure 5.2 suggests 

that the clean values in the winters of 1985-1990 are higher 

than those in 1974-1980. This could be caused by three 

possible effects: 1) asp at MLO is larger in recent years than 

it was in the early years of lhe program; 2) instrument 

sensitivity is poorer for the new design lhan in the original 

instrument; or 3) the geometric averaging performed by the 

instrument produced lower values during clean conditions in 

the original design than the arithmetic averaging scheme in 

the new design. 

An experiment was performed at MLO during October 15, 

1990-January 16, 1991, to compare the existing 4-A. 

nephelometer with a new high sensitivity three-wavelength 

(3-A.) nephelometer [Bodhaine el al., 199la]. Because of its 

high sensitivity, the 3-A. instrument could be operated at a 

shorter time constant, thus eliminating the seuling-time 

problem during diurnal events and giving belier sensitivity 

during clean background conditions. 

Data 

Hourly means for the existing 4-A. nephelometer and the 

new 3-A. nephelometer (both at 550 nm) for the entire period 

of the experiment are shown in Figure 5.22. The new 

instrument (dashed lines) reaches significantly lower values 

during the clean downslope flow events and occasionally 

reaches higher values during large upslope events. Figure 

5.23 shows the monthly means for October-January 

(ordinarily the cleanest time of the year) of the 4-A. instrument for the 1974-1981 and 1985-1990 time periods. The 

values during the earlier time period are lower by a factor of 

2-3. Figure 5.24 shows a comparison of monthly means of 

the new 4-A. and the new 3-A. nephelometer data during the 

period of the experiment. Figure 5.25 shows the means of 4-

). and 3-A. nephelomeler data for October-January for the 

10 -1- ~~~~~~~~~..,-~--....~---.~~.--

297 307 317 327 337 347 357 367 377 

Day of Year 1990 

Fig. 5.22. Hourly means of <Jsp for the four-wavelength (solid) and 

three-wavelength nephelometers at MLO during the period October 

24, 1990-January 16, 1991(DOY297-381). 

48 

I 

E 

0 

(/) 

0 

1-

<ll 

<( 

O· · · ············o. 

oeaa{l 

OOGOO 

....... o 

·e-· 

4->. Neph 1974-1981 (550 nm) 

4->. Neph 1985-1990 (550 nm) 

10 ·'+-~~~~,-~~~~~~~~~~~~~~ 

Ocl Nov Dec Jan 

Month 

Fig. 5.23. Monthly geometric means of the original 4f.. nephelometer data (solid) for 1974-1981, and the modified 4~ 

nephelometer data (dashed) for 1985-1990 at MLO. 
10 ·• 

:1 

, 1 

I . ..I 

E 

I_, 

Q) 

..... ·-r .....> 

«l , () 

,j CJ) r 0 

If) 

0 

I_, 

Q) 4-X Nephelomeler ~550 nml < 3-X Nephelomeler 550 nm 

l 0 ., 

Ocl Nov Dec Jan 

fig. 5.24. Monthly geometric means of the 4+.. and JA. 

nephelometer data for the period of the experiment, October 24, 

1990-January 16, 1991. The error bars are 1 standard deviation on 

either side of the mean. 

period of the experiment, and the October-January means for 

the Jong-term record during 1974-198 1 and 1985-1990 (for 

the two versions of the 4-1.. nephelometer). All Jong-term 

average data shown here are nighttime data only (1000-1800 

UT). 

Conclusion 

The data presented here show that the existing 4-1.. 

nephelometer is not sensitive enough to measure the 

background nighttime aerosol at MLO. However, even 

though the new 3-1.. nephelometer is sensitive enough to do 

the job, it still did not record values during the 1990-1991 

period that were as low as those measured during the 

beginning period of data at MLO (1974-1981). This could 

be due to the fact that the 3-1.. instrument and the existing4-I.. 

instrument (1985-1990) perform an arithmetic mean, 

whereas the original 4-1.. instrument (1974-1981) performed a 

I 

to·• 

E 

Winter 1990-1991 

4-Wave 

• 3-Wave 

• 

Long-Term Record 

1985-1990 

1974-1981 

• 

• 

~ ·1 

<10" ~~~~~~~~~~~~~~~~ ~{auna Loa Neph (550 nm) Dala 

Fig. 5.25. Geometric means of the October-January, 4+.. and JA. 

nephelometer data during the entire winter 1990-1991 experiment, 

and the long-term geometric means of the original 4.1.. nephelometer 

data (1974-1981) and the modified 4-1.. nephelometer data 

( 1985-1990). 

geometric mean. Or, it is possible that the actual background 

scattering coefficient at MLO has increased by about 10% 

since the beginning of the record. This is seen as the 

difference between the "3-Wave" point and the "1974-1981" 

point in Figure 5.25. 

5.2.2. FRONT RAXGE LIDAR, AIRCRAFT, AND BALLOON 

EXPERIMENT 

Introduction 

The first FRLAB experiment was conducted on July 26, 

1989, and the second was conducted on May 23-24, 1990. 

For these experiments, NOAA's CMDL and ARL scientists 

flew the NOAA King Air aircraft instrumented with a CN 

counter, a three-wavelength nephelometer operating at 449, 

536, and 690 nm, and an aethalometer; NOAA 's WPL 

scientists operated C02 (10.59 μm) and ruby (694.3 μ m) 

lidars; and the University of Wyoming scientists flew a 

balloon carrying a two-wavelength backscattersonde capable 

of operating at 480, 700, or 940 nm. Results of the two 

experiments were presented by Bodhaine et al. (1990, 1991b]. 

Logistics 

Because of the occurrence of high cirrus clouds, the ruby 

lidar was used to test the atmosphere until clear conditions 

were observed. Test shots began at about 2100 LDT on the 

night of each flight and continued at 30-minute intervals 

until satisfactory conditions were obtained (usually at about 

midnight when the high cirrus clouds dissipated). Regular 

shots by both lidars commenced at this time. 

The NOAA King Air aircraft, which was standing by at 

the Jefferson County Airport (just south of Boulder), took off 

at just after midnight on all 3 days, and the balloon carrying 

the backscattersonde was launched from the Marshall field 

site at about the same time. 

Lidars 

The C02 Jidar operates primarily at a wavelength of 

10.59 μm, has a 0.3-m aperture, and typically transmits 10 

pulses s·1, averaging 1000 pulses to compute backscattering 

profiles. However, it is grating-tunable and can be made to 

operate at other nearby wavelengths. For FRLAB we took 

data at three wavelengths: 10.59, 9.57, and 9.28 μ m. 

Signals at these wavelengths arise solely from particulates 

and are much weaker than signals at the ruby wavelength 

(694.3 μm); hence coherent detection is employed, and the 

retrieved profiles are referenced to internally generated shot 

noise and a hard-target calibration. The C02 lidar can also 

measure the Doppler shift of the backscattered energy and, 

therefore, the radial component of the wind. By scanning its 

beam in a vertically oriented conical pattern, it can determine the horizontal wind profiles averaged over the diameter 

of the cone at the altitude in question. 

The WPL systems were located near the intersection of 

Broadway Avenue and Baseline Street in Boulder (39.991-

1 'N, 105.2594 'W, 1.677 km), and data were acquired nearly 

simultaneously. The C02 and ruby lidar profiles obtained on 

May 23, 1990, are shown in Figure 5.26. The boundary 

49 
10-io 

\ 

20 - I 

I 

I 

18 - \ 

\ ) t Rlby Udar 

! ', Trne· 6 34 Z 

C02 Udat \ . 

e I 

Tme: 621 Z \ 

\ ~ I 

..J I 

I U) .,,--.1 c( 

Cl> 

"O 

~ 8 

< 

6 

4 

2 

10-10 10-t 10·8 

p {m-1 s(1) 

Fig. 5.26. Backscatter profile at 10.59 μm for the May 23, 1990, 

balloon flight {lower scale) with 0.5-km range averaging and 0.5-km 

venical spacing. Also shown is the concurrent ruby lidar backscatte r profile (upper scale) at the same 0.5-km spacing and resolution. 

layer extends to about 6 km, where a small relatively clean 

region appears; the backscatter signal then decreases until 

about 12-km altitude, the region of the tropopause. 

Aircraft 

The NOAA King Air research aircraft (Beechcraft C-90) 

was used to measure meteorological parameters, aerosol 

concentration, size distribution, and scattering coefficient of 

atmospheric aerosols during FRLAB [Wellman et al., 1989]. 

A LORAN system is installed aboard the aircraft for 

determination of aircraft position. 

Data from all instruments are digitized using an aircraft 

data acquisition system (Science Engineering Associates, 

Model M200) and are recorded on a 40-MB tape drive. Data 

are sampled every 0.5 seconds and recorded to a tape 

cartridge. Most aspects of the Model M200 data acquisition 

system are controlled by user-modifiable text tables. These 

user tables control acquisition, computation, display, and 

storage of measured data. 

Aerosol measurements were performed using an ASASPlOOX, FSSP-100, CN counter, three-wavelength nephelometer, and an aethalometer. The aethalometer has been 

described by Hansen and Rosen (1984). Figures 5.27 and 

5.28 show the temperature and humidity profiles for May 23, 

1990. The <Jsp profile for May 23, 1990, is shown in Figure 

5.29; note the boundary layer extending up to the 500-mb 

level and the clean region between 500 and 550 mb. 

Balloon 

The backscattersonde is a balloonbome instrument that 

measures the amount of light backscallered from a xenon 

flash lamp triggered about once every 7 seconds. The 

sensitive volume is on the order of 1 ml within a few meters 

of the balloonbome package. The irtstrument is sufficiently 

sensitive to measure the scattering at 30-km altirude with a 

~lay 23. 1990 9 

8 

400 ........ ........ 

.D 

E 

7 E 

..__.... ~ 

..__, 

Q) 500 6 .....l (/) 

s... 

;:j ~ 

(/J 

(/J 

Q) 

s... 600 

5 Q) 

'U 

;J 

0.. 4 

_, 

_, 

<i: 

700 3 

800 -- Bolloon Ascent -- Aircr,.ft Ascent 2 

········ Aircraft Descent 

I 

10 20 

900'f-~~...-~~.-~-,r-~~~~~~~-l­

- 40 -30 - 20 - 10 0 

Temperature (°C) 

Fig. 5.27. Balloonbomc and aircraft measurements of temperature 

on May 23, 1990. 

50 

300 

May 23, 1990 9 

8 

400 ........ ........ f L 7 E 

.D ~ 

E ..__.... 

..__, 8 .....l 

500 ································· (/) Q) ··::.-.... 

s... :::;g 

;:j 5 (/J Q) 

(/J 'U 

Q) 600 ;:j s... _, 0.. 4 ~ 

-

<i: 

700 3 

800 -- Balloon Ascent 2 

- - Aircroft Ascent ········ Aircraft Descenl 

900 t 

0 20 40 60 80 100 

Relative Humidity (%) 

Fig. 5.28. Balloonbome and aircraft measurements of relative 

humidity on :Vl'ay 23, 1990. Aircraft relative humidity was 

calculated using the Goff-Gratch relations given by List [ 1949]. 
7 

6 

500 

E 

~ 

5 

.....l 

if) 

600 ~ 

4 Q) 

"O 

;::J 

....... 

700 3 ..... 

~ 

800 2 

-- 449 nm -- 636 nm ········ 690 nm 

900+-~~~~~~~~~~~~~~~~ ........ 

JO ·• 10 .. 10 .• 

Aerosol Scatter (m - 1

) 

Fig. 5.29. Aircraft descent measurements of aerosol scattering 

extinction at 449, 536, and 690 nm on May 23, 1990. 

signal-to-noise ratio of about 50-1. The data product is 

similar 10 that produced by a typical lidar system. Standard 

meteorological parameters are also measured in a sounding 

including pressure, air lemperature, and relative humidity. 

This instrument has been described in detail by Rosen and 

Kjome [1991). 

The backscaltersonde data profile for May 23, 1990, is 

shown in Figure 5.30; the boundary layer below 500 mb and 

the clean region between 500 and 550 mb appear as seen 

similarly in the lidar and aircraft data. 

Conclusion 

Lidar profiles obtained routinely are difficult to calibrate 

because the return signal is the sum of both aerosol and 

molecular backscatter, and it is difficult to assign an absolute 

value to a point on the profile. A common calibration 

method involves locating the cleanest region of the profile 

and then assigning an aerosol backscatter value, usually zero 

or some small, c limatologically obtained value. Furthermore, in the absence of a simultaneous radiosonde ascent, a 

standard atmosphere must be assumed in order to estimate 

molecular scatter. The FRLAB experiment was designed to 

perform absolute aerosol scattering measurements in 

conjunction with lidar measurements in order to characterize 

a calibration for lidar data. 

The ASASP and FSSP probes provided aerosol size 

distribution data that could be used to calculate aerosol 

backscatter. The nephelometer measured the aerosol 

~lay 23, 1990 9 

Ascent 

8 

400 ,.....,_ 

....-.. 

..c 

E 

7 c: 

~ 

......., 6 .....l 

Q) 500 

s... 

if) 

~ ;::J 

(/) 5 Q) 

(/) 

Q.) 600 s... 

0... 

"O 

;::J 

• ..... 

..... 

-

< 

700 3 

800 2 

940 nm 700 nm 

900 I 

0.01 0. 1 10 

Aerosol Backscatter Ratio 

Fig. 5.30. Balloonbome measurements up to 300 mb of aerosol 

backscatter ratio, aerosol/Rayleigh, at 940 and 700 nm o n May 23, 

1990. 

scattering properties directly, allowing an est imate of 

backscatter. Finally, the backscattersonde measured the 

aerosol scatter directly in a manner similar to the lidar; 

however, the sonde also measures temperature and pressure, 

allowing a more accurate estimate of air density and 

molecular scalter. Work is presently in progress to accurately characterize the lidar profiles using data from this 

experiment. 

5.2.3. FIRST GROUND-BASED INTERCOMPARISON OF 

SBUV-2, S/N-2, AND DOBSON SPECrROPllOTOMETER 83 

51 

In early April 1990, comparison total ozone and ozone 

vertical distribution (Umkchr) observations were made for 

the first time with Dobson spectrophotometer 83 and with 

satellite ozone spectrometer SBUY-2, S/N-2 operated at 

ground level [Komhyr et al., 1990; Heath and Komhyr, 

1991). The work was conducted at CMDL in Boulder and at 

the research and instrument manufacturing facility of the 

Ball Aerospace System Division located 3 km cast of 

Boulder. The SBUV-2, S/N-2 instrument, built by Ball 

Aerospace Systems Division, is scheduled for launch in 

November 1991 aboard the NOAA-13 satellite. It is one of a 

series of SBUV -2 instruments being flown on the TIROS-N 

series of NOAA satellites. Two satellites of the series, 

NOAA-9 carrying SBUV-2 S/N-1 and NOAA-11 carrying 

SBUV -2 S/N-4, were launched in October 1984 and October 

1989, respectively. 
Comparison total ozone observations were made with 

Dobson spectrophotometer 83 and with the ground-based 

SBUY-2, S/N-2 satellite ozone instrument on April 7 

between 8:22 and 11 :40 MST. Observations with both 

instruments were made on standard A and D Dobson 

instrument wavelengths. Effective ozone absorption 

coefficients from the two instruments used in processing the 

observational data were based on the laboratory 

measurements o f Bass and Paur [ 1985). 

Total ozone amounts obtained with Dobson spectrophotometer 83 and with ground-based SB UY-2, S/N-2 

satellite ozone instrument agreed in the mean Lo 0.8%, but 

exhibited an air mass dependency (Figure 5.31) with the 

SBUY-2 measuring 1.5% more ozone at an air mass of 1.95, 

but 2.8% less ozone at an air mass of 1.2. The reason for 

this discrepancy in results is not known. TOl\IS overpass 

data over Boulder April 7 agreed with Dobson instrument 83 

data Lo within about 0.5%. This agreement is better than that 

which has been observed during similar observations made 

in the past al MLO (where TOMS ozone values were on 

average about 4% higher than Dobson instrument 83 values), 

but falls within the variability of the MLO comparison data. 

The NOAA-11 SBUY-2 satellite ozone instrument measured 

1.4% more ozone over Boulder on April 7 than did Dobson 

instrument 83. 

Comparison Umkehr observations were made April 4, 

1990, in Boulder with Dobson spectrophotometer 83 and 

with ground-based SBUY-2, S/N-2 operated at Dobson 

instrument wavelengths. Inversions of the C-wavelcngth 

observational data for both instruments to obtain ozone 

vertical distributions in Umkehr layers 1-9 were performed 

by C. L. Mateer (Scarborough, Ontario, Canada) who 

recently devised an improved data reduction algorithm. 

,-.._ \(\-.-~~~~~~~~~~~~~~~~~~~--. 

~ ..._, 

UJ ""' 

u ZM 

UJ 

~ 

~N 

LL 

0 

("") 

Oo 

("") 

co 7 0 

(./') N 

:::'.) I 

z 

~ ';' 

>"'I" 

:::'.) I 

CD 

(./') ";'-+-~-.-~-....~-....~--.-~....,.~---.~---.~--.~~.-----i 

2.0 1.5 1.0 

MU 

fig. 5.31. Total ozone differences measured April 7, 1990, in 

Uoulder, Colorado, with Dobson spectrophotometer 83 and 

ground-based satellite ozone instrument SUUV-2, S/N-2. 

Results in Umkehr layers 3-9 agreed to within ±7%, with 

an agreement of 1.1 % in the region of ozone maximum 

(Umkehr layer 4). A skewness in the comparison data was 

evident, however, with the SBUY-2 ozone values somewhat 

larger at the higher altitudes and smaller at the lower 

allitudes than Dobson instrument 83 data. Agreement was 

poor in Umkehr layers 1 and 2 where the sensitivity of the 

Umkehr method to ozone is poor. 

5.2.4. STRATOSPHERIC WATER VAPOR MEASUREMENTS L\f THE P OLAR R EGIONS 

Measurements to investigate the role of PSCs in ozone 

depletion were carried out as part of two cooperative 

programs. At Alert, Northwest Territories, Canada, and at 

SPO, profiles were obtained as part of a joint effort with the 

University of Wyoming [Komhyr and Rosson, 1990). At 

McMurdo, Antarctica, two profiles were obtained in 

September and October in a collaborative effort also with the 

University of Wyoming. 

At Alert the concurrent measurements of water vapor and 

aerosol backscatter confirmed the formation o f PSCs in the 

Arctic polar vortex at temperatures warmer than the frost 

point of water. This result shows that the particles are not 

water ice crystals but HN03 •3H20 [Rosen el al., 1989, 

1990). Because of the lack of ice crystal formation, there 

appears to be little dehydration in the Arctic vortex associated with the formation of PSCs. This is consistent with 

aircraft-based measurements in other parts of the Arctic 

[Fahey et al., 1990). 

Jn Antarctica several stratospheric water vapor profiles 

were obtained in the period from May to November (Figure 

5.32). In May and June mixing ratios are still relatively high 

with a dryer region centered about 13 km. These profiles are 

similar Lo what is seen in the spring at Boulder but with 

slightly higher average mixing ratios. During May frostpoint temperatures in the region above 10 km are 5'-lO'C 

cooler than the ambient temperature so that the stratosphere 

is not close to saturation at any point. Although water vapor 

mixing ratios by June are nearly identical Lo those in May, 

the stratosphere has cooled greatly and saturated conditions 

prevail from 16-22 km. By August (a flight in July was not 

successful) the stratosphere from 11-22 km is -80'C or 

colder, reaching -90'C at 20 km. Saturated conditions 

prevail throughout the stratosphere to about 20 km. 

Throughout the winter the decrease in water vapor closely 

follows the drop in temperatures. Backscatter sonde profiles 

in July and August [Rosen el al., 1991) show that during July 

there were extensive PSCs in the region of temperatures 

below -80'C at altitudes between 15-20 km. By late August 

the PSCs were primarily in the region below 15 km and the 

strong backscatter signal extends well into the troposphere 

suggesting that the particles are precipitating out of the 

stratosphere into the troposphere. The saturated conditions 

of the troposphere appear Lo prevent these particles from 

evaporating. 

52 

By October, stratospheric temperatures have warmed 

considerably with no regions colder than about -75'C but the 
. /'·-. . ... ... ······· ... ' ,,......._20 

E 

/ 

r· ······· I 

I 

w 

0 

:::::> 

II-

_J 

t •• .. ; ....... · / 

1:: / 

/i ; \ :. •' ·, ...... \. 

·, · .. '• 

· .... ,, ·· .. ~ 

I 

I 

<( 10 ·-.::. ..... :~·.·.:.::...., ... -4,....,,.~.--:;:,, 

SOUTH POLE 

- 23 llAY 90 

-·- t6 JUN 90 

-·-J1Aur.90 

'"' 20 OCT 90 

··-.. •2 !A>J 'I I 

0 ~~ ............................................................... .......__'-'-' ........... '-'-' ...................................... .......__~ ........... 

0 1 2 3 4 5 6 7 8 

WATER VAPOR MIXING RATIO (ppmv) 

Fig. 5.32. Water vapor mixing ratio (ppmv) profiles in the 

stratosphere over SPO from five balloonborne frost·point 

hygrometer flights. 

stratosphere remains extensively dehydrated (Figure 5.32) 

with much of the region between 11-20 km as dry as in 

August. By November temperatures above 15 km h ad 

warmed by l O'C, but the stratospheric water vapor content is 

essentially unchanged from October. This suggests that even 

in November the antarctic vortex continues to retain the 

material and prevents the rapid exchange of air from outside 

the vortex at these altitudes. Also in November (and even 

October) temperatures appear too warm to allow continuing 

water vapor removal. 

A mid-austral summer (January) profile (Figure 5.32) 

shows drier conditions above 20 km than during the winter 

but somewhat wetter values between 10-20 km. In January 

conditions above 12 km are still drier than at the beginning 

of the winter (May-June). Evidently significant rehydration 

takes place from J anuary to May. 

The two profiles obtained at McMurdo about 2 weeks 

apart in September and October show that the strong 

dehydration of the st~ato sphere seen at SPO extends to much 

of Antarctica. During the 2 weeks between the profiles, the 

boundary of the vortex pushed south of McMurdo [Hofmann 

et al., 1991) and then moved north once again before the 

flight of October l. 

5.3. REFERENCES 

Angell, J.K., Influence of equatoria l QBO and SST on polar total 

ozone and the 1990 Antarctic ozone hole, Geophy. Res. Lell., 17, 

1569-1572, 1990 

Bass, A.M., and R.J. Paur, The ultraviolet cross-sections of ozone: 

l. The measurements, in Atmospheric Ozone, edited by C.S. 

Zerefos and A. Ghazi, pp. 606-610 D. Reidel, Dordrecht, 

Holland, 1985. 

Bodhaine, B.A., The GMCC four-wavelength nephelometer, in 

Light Absorption by Aerosol Particles, H.E. Gerber and E.E. 

Hindman, (Eds.), Spectrum, Hampton, VA, 149-168, 1982. 

Bodhaine, B.A., Barrow surface aerosol: 1976- 1986, Atmos . 

Environ., 23, 2357-2369, 1989. 

Bodhaine, B.A., and J.J. DeLuisi, An aerosol climatology of Samoa, 

J. Atmos. Chem., 3, 107-122, 1985 . 

Bodhaine B.A., and M.K. Shanahan, Condensation nucleus and 

aerosol scattering extinction measurements at the South Pole 

Observatory: 1979-1988, NOAA Data Rep. ERL CMDL-1 , 

Climate Monitoring and Diagnostics Laboratory, Boulder, CO, 

148 pp .. 1990. 

Bodhaine, B.A., J.I. DeLuisi, J.M. Harris, P. Houmere, and S. 

Bauman, Aerosol measurements at the South Pole, Tel/us, 388, 

223-235, 1986. 

Bodhaine, B.A., J.J. DeLuisi, J.M. Harris, P. !Ioumere, and S. 

Bauman, 1987, PIXE analysis of South Pole aerosol, Nuclear 

Instr. Meth., 822, 241-247, 1987. 

Bodhaine, B.A., I.I. DeLuisi, J.F. Boatman, M.J. Post, and J.M. 

Rosen, The front range lidar, aircraft, and balloon experiment, 

NOAA Data Rep. ERL CMDL-2, Climate Monitoring and 

Diagnostics Laboratory, Boulder, CO, 27 pp., 1990. 

Bodhaine, B.A., N.C. Ahlquist, and R.C. Schnell, Three-wavelength 

nephelometer suitable for aircraft measurement of background 

aerosol scauering coefficient, Atmos. Environ., 25A, 2267-2276, 

199la. 

Bodhaine, B.A., J.J. DeLuisi, J.F. Boatman, Y. Kim, D.L. 

Wellman, R.L. Gunter, M.J. Post, R.E. Cupp, T. McNice, J.M. 

Rosen, P.J. Sheridan, R.C. Schnell, D.M. Garvey, A.E. Wade, 

and R.G. Steinhoff, The second front range lidar, aircraft, and 

balloon experiment, NOAA Data Rep. ERL CMDL-8, Climate 

Monitoring and Diagnostics Laboratory, Boulder, CO, 142 pp., 

199lb. 

Cru ti.en, P.I., Troposphe ric ozone: An overview, in Tropospheric 

Ozone, edited by l.S.A. Isaksen, Reidel, New York, 3-32, 1989. 

DeLuisi, J.J., D. U. Longenecker, C.L. Mateer, and D.J. Webbles, 

An analysis of northern middle-latitude Umkehr measurements 

correcte d for stratosphe ric aerosols for 1979-1986, J. Geophys. 

Res., 94(D7), 9837-9846, 1989. 

Fahey, D.W., K.K. Kelly, S.R. Kawa, A.F. Tuck, M. Lowenstein, 

K.R. Chan, and L.E. Heidt, Observations of denitrification in the 

winter polar stratosphere, Nature, 344, 321-324, 1990. 

Fung, I., J. John, J. Lerner, E. Matthews, M. Prathe r, L.P. Steele, 

and P.J. Fraser, Three-dimensional model synthesis of the global 

methane cycle, J. Geophys. Res. 96, 13,033-13,065, 199 1. 

Hansen, A.D.A., and H. Rosen, The aethalometeF-an instrument 

for the real-time measurement of optical absorption by aerosol 

partic les, Sci. Total Environ., 36 , 19 1-196, 1984. 

Harris, J.M., The GMCC atmospheric trajectory program, NOAA 

Tech. Memo., ERL ARL-1 16, 30 pp., NOAA Environmental 

Research Laboratories, Boulder, CO, 1982. 

Harris, J.M., and B.A. Bodhaine (eds.), Geophysical Monitoring for 

ClimLitic Change, No. 1 I. Swnmary Report 1982, pp. 67-75, 

NOAA Environmental Research Laboratories, Boulder, CO, 1983. 

Harris, J.M., and J.D. Kahl, A de$criptivc atmospheric transport 

climatology for the !11auna Loa Observatory using clustered 

trajectories,]. Geophys. Res., 95(D9), 13,65 1-13,667, 1990. 

53 

Heath, D.F., and W.D. Komhyr, Preliminary ground-based intercomparison of SBUV-2, S/N-2 and world standard Dobson 

spectrophotometer 83, paper presented at the meeting of the 20th 

General Assembly of the International Union of Geodesy and 

Geophysics, Vienna, Austria, August 11 -24, 1991. 

Hofmann, D.J., and T. Deshler, Evidence from balloon measurements 

for chemical depletion of stratospheric ozone in the Arctic winter 

of 1989-90, Nature, 349, 30-305, 1991. 
Hofmann, D.J., SJ. Oltmans, and T. Deshler, Simuhaneous 

balloonbome measurements of stratospheric water vapor and ozone 

in the polar regions, Geophys. Res. Lett., 18 , JOJ J-1014, 1991. 

Komhyr, W.D., Operations handbook-ozone measurements to 40 

km, altitude with model 4A electrochemical concentration cell 

(ECC) ozonesondes (used with 1680-MHz radiosondes), NOAA 

Tech. Memo ERL ARL 149, NOAA Environmental Resea rch 

Laboratories, Boulder, CO, 49 pp., 1986. 

Komhyr, W.D., Electrochemical concentration cells for gas analysis, 

Annals de Geophysique, 25, 203-210, 1969. 

Komhyr, W.D., and R.M. Rosson (Eds.), Climate Monitoring and 

Diagnostics Laboratory, No. 18; Summary Report 1989, 141 pp., 

NOAA Environmental Research Laboratories, Boulder, 

Colorado, 1990. 

Komhyr, W.D., R.D. Grass, and R.K. Leonard, Dobson 

spectrophotomete r 83 : A standard for total ozone measu rements, 

1962-1987,J. Geophys. Res., 94(0 7), 9847-9861, 1989. 

Komhyr, W.D., S.J. Oltmans, R.D. Grass, and R.K. Leonard, 

Possible influence of Jong-te rm sea surface temperature 

anomalies in the tropical Pacifi c on global ozone, Can. J. Phys. , 

69, 1093- 1102, 199 1. 

Komhyr, W.D., R.D. Evans, R.D. Grass, G.L. Koenig, J.A. Lathrop, 

and D.M. Quincy, Dobson spectrophotometer, ECC ozonesonde, 

and ground-based NOAA SBUV-2, S/N-2 satellite instrument 

comparison observations, NOAA Data Report ERL CMDL-6, 17 

pp., 1990. 

List, R.J., Smithsonian Meteorological Tables, Smithsonian 

Institution Press, Washington, DC, 1949. 

Massey, D.M., T.K. Quakenbush, and B.A. Bodhaine, Condensation 

nuclei and aerosol scattering extinction measurements at Mauna 

Loa Observatory: 1974-1985, NOAA Data Rep. ERL ARL-14, 

NOAA Air Resources Laboratory, Silver Spring, MD, 174 pp., 

1987. 

Mateer, C.L., and H.U. Dutsch, Uniform evaluation of Umkehr 

observations from the world ozone network: Part 1. Proposed 

standard Umkehr evaluation technique, National Center for 

Atmospheric Research, Boulder, CO, I OS pp., 1964. 

McPeters, R.D., and W.D. Komhyr, Long-term changes in 

SBUV(fOMS relative to world primary standard Dobson 

spectrophotometer 83, / . Geophys. Res., 96(D2), 2987-2993, 

1991. 

Miller, J.M., (Ed.), Geophysical Monitoring for Clima tic Change, 

No. 3: Summary Report 1988, NOAA/ERL Air Resources 

Laboratory, Boulder, CO, 1975. 

Quakenbush, T.K., and B.A. Bodhaine, Surface aerosols at the 

Barrow GMCC observatory: data from 1976 through 1985, 

NOAA Data Rep. ERL ARL-10, NOAA Air Resources 

Laboratory, Silver Spring, MD, 1986. 

Rosen, J.M., and N.T. Kjome, The backscattersonde: A new 

instrument for atmospheric aerosol research, Appl. Opt., in press, 

1991. 

Rosen, J.M., N.T. Kjome, and S.J. Oltmans, Balloonbome 

observations of backscatter, frostpoint, and ozone in polar 

stratospheric clouds at the South Pole, Geophys. Res. Lett., 18, 

171-174, 1991. 

Rosen, J.M., N.T. Kjome, and S.J. Oltmans, Observations of 

backscatter, particle concentration, and frostpoint in north polar 

vortex stratospheric clouds, Geophys. Res. Lett. , 17, 127 1-1274, 

1990. 

Rosen, J.M., S.J. Oltmans, and W.F. Evans, Balloonbome 

observations of PSCs, frostpoint, ozone, and nitric acid in the 

north polar vortex , Geophys. Res. Lett., 16, 79 1-794, 1989. 

Schnell, R.C., S .. Liu, S.J. Oltmans, R.S. Stone, D.J. Hofmann, E.G. 

Dutton, T. Deshler, W.T. Sturges, J.W. Harder, S.D. Sewell, M. 

Trainer, and J.M. Harris, Decrease of summer tropospheric 

ozone concentrations in Antarctica, Nature, 351, 726-729, 1991. 

54 

Spivakovsky, C.M., R. Yeich, J.A. Logan, S.C. Wofsy, M.B. 

McElroy, and M.J. Prather, Tropospheric OH in a threedimensional chemical tracer model: An assessment based on 

observations of CH3

CC13, /. Atmos. Res., 95, 18,441-18471, 

1990. 

Stolarski, R.S., A.I. Krueger, and M.R. Schoeberl, Total ozone 

trends from TOMS data, in Atmospheric Ozone, edited by R.D. 

Byokov and P. Fabian, 185- 188, 1989. 

Wellman, D.L., M. Luria, C.C. Van Valin, and J.F. Boatman, The 

use of an airborne air sampling platform for regional air quality 

studies, NOAA Tech. Rep. ERL 437-ARL JO, Air Resources 

Laboratory, Boulder, CO, 1989. 

World Meteorological Organization, Report of the International 

Ozone Trends Pane/-1988, Volwne 1, Rpt. No. 18, 44 1 pp., 

WMO Global Ozone Research and Monitoring Project, 

Washington, D.C., 1988. 
6. Acquisition and Data Management 

G. HERBERT (Editor), M. BIENULIS, AND J. Mc CUTCHEON 

6.1. CONTINUING PROGRAMS 

6.1.1. STATION CLIMATOLOGY 

The climatology of surfac e weather observations at the 

CMDL observatories is based on hourly-average measurements of the wind direction, wind speed, station pressure, air 

and dewpoint temperature, and precipitation amount. The 

14-year station climatologies are an important record for the 

interpretation of measured values of aerosols, trace gases, 

and climatic change. The sensors currently in use were 

selected not only for high accuracy but also for ruggedness, 

to minimize failures in the extreme conditions of the polar 

region (fable 6.1). To the extent that it is practical, WMO 

siting standards are followed. 

Table 6.1 describes the disposition of the sensors as of 

January 1, 1990. The following changes were made 

throughout the year: MLO anemometer 782 replaced 93 1 on 

DOY 200 only to be replaced again by 931 on DOY 212. 

Also at MLO, anemometer 883 was replaced by 876 on DOY 

200. Later on DOY 230 anemometer 876 was replaced by 

782. Thermometer 8805 replaced 8807 on DOY 293. In 

SMO anemometer 458 replaced 782 on DOY 109. T hermometers 7 and 9 were replaced by 8803 and 8806 respectively on DOY 20. Thermometer 2 wns replaced by 8008 on 

DOY 95. On DOY 109 the new hygrometer was installed, 

thus dewpoint sensor 1 was replaced by 50. At SPO, 

anemometer 585 was replaced by 168 on DOY 340. 

Barrow 

Descriptions of the BRW station and its climate are given 

in previous CMDL Summary Reports [e.g., DeLuisi, 1981]. 

Wind roses of hourly average resultant wind direction and speed 

are presented in 16 direction classes and 4 speed classes (Figure 

6.1). Winds from the "clean-air" sector, north-nonheastsoutheast directions, occurred 61 % of the time as compared to 

65% for the 13-year climatology. As was the case in 1989, the 

distribution of wind by direction for the 1990 wind rose shows a 

higher percentage of winds from the southwest quadrant (25%) 

compared to the 13-year climatology (19%). The anomalous 

southwest winds were recorded during the months JanuaryMarch. The year's maximum hourly-average wind speed of 24 

m s·1 occurred on December 18. 

New maximum wind speeds were measured during October 

and December (fable 6.2), and the maximum pressure for 

April and the minimum in August exceeded the 13-year 

climatology. The average temperature for 1990 was within 

0.5'C of the climatological average of -12.7°C. A record 

minimum temperature was reported for November. The year's 

minimum temperature of -42.l 'C occurred on February 23, 

and the maximum of 17 .9°C on July 16 ties the record high 

temperature for July. Unlike 1989 when monthly mean 

temperatures were above normal for 9 months out of the year, 

in 1990 the monthly mean temperatures and pressures, as well, 

were not significantly different from normal. 

Instrument heights: wind, 16.7 m; pressure, 9 m (MSL); air 

and dewpoint temperature, 2.5 m. Wind and temperature 

instruments are on a tower 25 m northeast of the main 

building. Precipitation amounts are only valid for the period 

May-September. 

MaunaLoa 

In this report the climatology of MLO is regarded as 

consisting of two distinct regimes because the bimodal 

TABLE 6.1. CMDL Meteorological Sensor Deployment 1990 

BRW MLO SMO SPO 

Sensor Serial Elevation, Serial Elevation, Serial Elevation, Serial Elevation, 

No. m No. m No. m No. m 

Primary anemometer• 576 16.7 931 8.5 782 13.7 585 12.2 

Scoondary anemometer"' 883 38.5 

Pressure transducert 2366 9 225 3397 752 30 8 2841 

Mercurial barometer 641 9 278 3397 961 30 

Air temperature A; 8801 2.5 8807 1.7 7 9 703+ 2.2 

Air temperature B§ 8802 15.3 8809 37.8 8 2.3 701+ 23.2 

Air temperature C; 8 3.1 46 2.0 2 9.0 835+ 2.2 

Dewpoint temperature hygrometer*• 8 3.1 46 2.0 I 9.0 3720 2.2 

•Aerovane, Bendix, Inc., model no. 141, Baltimore, MD. 

t Pressure transducer, Rosemount, Inc., model no. 1201Flb, Minneapolis, MN. Heights of all pressu re sensors are given with respect to MSL. 

iLinearized thermistors, Yellow Springs Inst. Co., model no. 44212, Yellow Springs, Ohio, except at SPO. 

Platinum resistance thermometer, Yellow Springs Inst. Co., model no. RTD-385, Yellow Springs, Ohio 

§Thermometer, positioned at the top of the local sampling tower to facilitate an estimation of boundary layer stability . 

.. llygrothermometer, Technical Services Laboratory model no. 1063, Fort Walton Beach, FL. 

55 
' 

BARROW 

1990 

w 

-WIND SPEED -·-(M/S) 

--5 , llS< 5 

=s ~ ws < 10 

c:=:Jll'S ~ 10 

" . 

' 

WIND ROSE 

E 

WlllD FREQ 

BARROW 

1977 - 89 . _ .. · 

IWID SPEED (M/ S) 

- -5,WS<S 

=i5 ~!I'S< 10 

c:=:JWS ~ 10 

.... -·-· 

' .. . ·1···-.. -.... ..... ; .... . 

: .. ··:·····-· 

·······-. 

·······-t-··· ·-.... __ 

········$ ·· 

Fig. 6.1. Wind rose of surface winds for BRW for 1990 Oeft) and 1977-1989 (right). 

TABLE 6.2. BRW 1990 Monthly Climate Sununary 

Jan. Feb. March April May June July Aug. SepL Oct. 

Prevailing wind ENE w NE WSW ESE E ENE E ENE ENE 

direction 

Average wind 5.0 6.2 5.J 6.0 6.J 4.8 5.7 7.7 7.5 7.6 

speed (m s ·

1) 

Maximum wind JO 15 J4 J5 J3 JO J6 J8 16 20 

speed* (m s·1) 

Direction of max. 69 71 203 107 86 101 236 98 78 63 

wind* (deg.) 

Average station 10J7.3 J017.3 1014.9 IOJ8.8 JOJ4.2 1009.8 J013.7 JOJ2.9 J006.9 J007.6 

pressure (hPa) 

Maximum pressure• 1038 J038 1041 J043 1026 1021 1025 1023 1020 1030 

(hPa) 

Minimum pressure• 992 J002 992 999 1003 997 JOOJ 985 988 989 

(hPa) 

Average air -30.8 -31.4 -24.4 -J3.5 -3.6 1.3 4.5 2.3 -0.3 -7.9 

temperature ('C) 

Maximum temperature• - 18 -19 -3 4 JO J8 11 7 - 1 

('C) 

Minimum temperature• -40 -42 - 39 -30 -18 -5 -2 -2 -5 - J9 

('C) 

Average dewpoint -33.6 - 34.7 - 27.l -15.4 -4.7 -0.3 2.9 0.8 -2.7 -9.9 

temperature ('C) 

Maximum dewpoint -19 - 2J - 3 -1 0 8 J5 9 3 -2 

temperature ('C) 

Minimum dewpoint -44 -47 -43 -32 -20 -5 -2 -4 -8 -2J 

temperature ('C) 

Precipitation (mm) 0 0 0 0 4 14 27 J9 9 0 

Instrument heights: wind, J6.7 m; pressure, 9 m (MSL); air temperature, 2.5 m; dewpoint temperature, 3. J m. Wind 

on tower 25 m northeast of the main building. 

*Maximum and minimum values are hourly averages. 

56 

.... -

Nov. 

NE 

6.4 

J7 

238 

J014.9 

1039 

993 

-21.7 

0 

-38 

-24.J 

-J 

-41 

0 

WIND ROSE 

.-···· 

lllND FREQ 

:: 

Dec. J990 

ENE ENE 

5.9 6.2 

24 24 

234 234 

10J9.7 1013.9 

1044 J044 

1000 985 

-26.9 -J2.3 

-2 18 

-38 -42 

-29.5 -J5.3 

-3 J5 

-42 -47 

0 73 

and temperature instruments arc 
distribution of the wind direction changes with the time of 

day. The night (downslope) period (1800-0600 LST) and the 

day period (0600-1800 LST) define the two regimes. The 

13-year night and day wind roser illustrate the two distinct 

wind patterns (Figure 6.2). 

Night regime. The 13-year night wind rose (Figure 6.2) 

shows that 91 % of all winds observed had a southerly 

component, southsouthwest southsoutheast. The 1990 wind 

rose (Figure 6.3) shows only a slightly higher percentage of 

southerly winds (93%) than does the 13-year rose. (Note that 

the difference appears greater due to the difference in 

scales.) S term-related winds (WS ~ 10 m s·1) with westerly 

and easterly components are evident in both the 1990 and 

13-year night wind rose in equal proportion, 7.5% and 7.1% 

respectively. The upslope or northerly component winds 

(northnorthwest-eastnortheast), about 5% of the time, are the 

results of the daytime, upslope flow extending into the 

evening hours. 

Day regime. The 13-year day wind rose (Figure 6.2) 

indicates that light wind speeds in the westnorthwesteastnortheast sector were observed 59% of the time. (Only 

48 hours with speeds greater than 10 m s·1 were reported 

from 1977-1989 .) This represents the upslope flow 

attributed to the daytime heating of MLO. The 1990 day 

wind rose (Figure 6.3) compares well with the 13-year rose, 

in that northerly wind components p revail 57% of the time. 

The day wind rose was more uniformly distributed in the 

light wind classes than that of the night wind rose which was 

due to the occurrence of variable wind directions during the 

transition periods of dawn and dusk, most of which were 

MAUNA LOA .... ··· ---- ~-·-- N··---~~····-·-..... 1977-89 _ ..... " .. --· 1· -·- ·· ... WIND ROSE 

NIGHT/··· - -- -t·- -··- --~ · .. _ 

,..~ - . -·:-· ..... ...... 

.... ,,.,... ---·-t·· ---.... ... ... .. ---·-·i··- .--f. 

+-· 

f 

l-···(·-\····· [·· 

\ 

WINO SPEED (M/S) 

-- 5 S WS < 5 

=5 S llS < 10 

c=JWS ~ 10 

.. ··r 

·1 

.< 

..._ 

' I 

; i i . l 

·-···t ···1· ··r-r-···· ~ 

I i 

WINO FREQ 

included in this regime. The percent frequency of occurrence of wind in the 10 m s· 1 or greater wind class was about 

the same for both periods since it was largely due to storm 

activity. 

The 1990 average day-night temperature difference was 

4.3 •c, and the average dewpoint depression for 1990 was 

5.6"C (Table 6.3). The year's maximum temperature of 18"C 

occurred on August 8, and the minimum of-S"C that tied the 

all time low occurred on March 2. The minimum temperatures occurred in conjunction with a severe snow storm when 

the pressure reached 762 mb equaling the low for the year. 

In spite of a very dry spring, the precipitation total of 1004 

mm was 153% of the 1977-1989 average precipitation. Only 

22 mm of precipitation were recorded from March-June. 

Samoa 

A comparison of SMO's 1990 wind rose (Figure 6.4) with 

that for the 13-year period shows a slightly higher percentage (65%) of "clean air" sector winds (northnorthwestsouthwest) in 1990 than for the 1977-1989 period (58%). (If 

air passing over the offshore island Aunu 'u is to be avoided, 

the southsoutheast wind sector (26%) cannot be considered 

in the "clean air" sector.) The peak hourly-average wind 

speed of 30 m s·1 occurred on February 4 during the passage 

of Typhoon Ofa. 

During the encounter with Typhoon Ofa, a number of new 

station records were established. The anemometer was 

operational throughout the storm and recorded a peak gust of 

46 m s-1• At its minimum, the hourly-average station pressure 

reached 979 hPa, a new record. A total of 156 mm of 

MAUNA LOA 

1977-89 

111\ y 

w 

I 

! 

... i .... !. 

Wiiio SPEED (M/ S) 

--5SWS<5 

=s S l!S < 10 

115 ~ 10 

~-...... 

! .. 

i 

-t --

' j 

. ; 

I 

--!-

i ... , •······ 

! 

I·········· 

•.. . .. I ·-$ 

WIND ROSE 

\ 

' 

···)··-· l-···i ·· 1·· E 

WIND FREQ 

r. 

Fig. 6.2. Wind roses of the surface winds for MLO for 1977-1989 night Oeft) and day (right). The distribution of resullant wind direction and 

speed are given in units of percent occurrence for the 13-year period. Wind speed is displayed as a function of direction in three speed 

classes. 

57 
MAUNA LOA .-·· ..... . .. ~ ----- ~.:-· 1990 .... 

NIGHT,· . -·····--· .... ---··· ~ -·--- ___ ; ___ _ 

i ........ .. r ....... ,,. ! 

.... ,,,..... . ..r·-·· ...... / ·' I 

-·-r-·-·---.... '- I i ... · .. .,~ 

--t-----... _ i -·· r. --------.... 

.-·· 

/ I j 

! : 

\~.. 1--(-·---1 .. --t .. -+.- --{··{·-

\._ \ \ \ \ . 

· ..... \ ·· .. ·· 

:>- .... __ ... ·-.... 

WIND SPEED ( 11/ S) 

"· "· 

.. 

-- 5 ' WS < 5 "--. .. 

=i5 S llS < 10 

c:=:JllS ~ 10 

. ·---!---··· ·--.... : . -1-· ---.. --... ~ ... --·"" . '· -... _____ ... _ J_ ____ . 

-·~~~:::~-~~i----~-~--~--::~:_._ ... ~ 

; 

.. -·· 

WIND ROSE 

' 

" 

\ 

•, 

..... 

· .... ..... 

\ \ \ . \ \ 

\ 

" 

.L~ ..l ..... b .. : i LI 

! 

f I , J 

i 

' 

! 

lllllD fREQ 

)'; 

MAUNA LOA 

1990 

DAY / 

•, 

.>.:. / 

, 

I/ 

I / 

.,. 

_.- -... 

.- ~:~_ ..... -· 111 -----~~--:~~----.. ,._ . WIND ROSE 

i ....... ---.. 

:~~~-- .--.-]-.~~----·-:-~~~--=:~.---.:~----.-·· ... ~;---: . .... >: ·--,-:: ... _ \ 

i I / 

11-(--{,-tH 

"\ \ ·-.. \ ·· .. 

lllllD SPEED ( 11/ S) 

Fig. 6.3. Wind roses of the surface winds for MLO for 1990 Night (left) and Day (right). The distribution of the resultant wind direction and 

speed a re given in units of percent occurrence for the year. Wind speed is displayed as a function of direction in three speed classes. 

precipitation was reported for the storm. While considerable 

damage was done to the facilities, the main sampling 

platforms remained operational. The solar-powered 

uninterruptible power supply provided power throughout the 

storm. The only interruption to the program was the 

overturning of the rain gauge from which the hourly average 

precipitation amounts are obtained. 

While a new station wind speed record was being set in 

February, 9 months of the monthly average values were 

above normal (fable 6.4). The average wind speed for the 

year was 1.2 m s·1 above normal. The average temperature 

for 1990 of 26.9'C is consistent with the 13-year average of 

27.0"C. The average pressure of 1000.8 hPa is 1.5 hPa 

higher than the 13-year average. The precipitation total for 

the year measured 2136 mm, which was 96 mm below the 

13-year normal. 

Instrument heights: wind, 13.7 m; pressure, 30 m (MSL); 

air temperature, 9 m. Wind and temperature instruments are 

on Lauagae Ridge, 110 m northeast of the main building. 

Pressure sensors are in the main building. 

South Pole 

The distribution of the surface wind direction in 1990 

(Figure 6.5) is nearly identical lo that of the 13-year pattern 

with "clean air" sector winds (grid northnorthwest-eastsoutheast) occurring 93.9% in 1990 compared to the 13-year 

average of 94.1 %. A slightly higher percentage of winds in 

the greater than 10 m s·1 range (6.8%) were observed in 1990 

than the long-term average of 4.1 %. While wind speeds were 

only slightly higher for the year (0.5 m s·1), the average for 

58 

June was 2 m s·1 greater than the 13-year average. The 

maximum hourly-average wind speed was 15 m s-1 on June 27. 

While the 1990 annual average temperature was within 

0.6"C of the 13-year average, the annual average pressure 

average was 2.6 hPa above normal (fable 6.5). On April 29 a 

new pressure of 715 hPa was recorded, surpassing the 

previous record by 8 hPa. Seven monthly average pressures 

were above normal. The average pressure for the April-July 

period was 5.7 hPa above normal. Of note, the monthly 

average pressure for May 1989 was IO hPa below the May 

normal. An abnormally warm -29"C was the minimum 

temperature for December. 

6.1.2. DATA M ANAGEMENT 

During 1990 the CAMS operated 97 .11 % of the time, 

excluding the lime the C02 CAMS in SMO was inoperative 

due to damage by Typhoon Ofa. Including the SMO C02 

CAMS, which experienced a 23% data loss, the total system 

operated 87.76% of the year. CAMS gathers data from those 

sensors that operate continuously at each of the four CMDL 

observatories. The performance of CAMS was monitored by 

comparing the number of data files recorded against those 

expected in the year. Tn the case of CAMS, there are data 

file tapes that are regularly recorded 12 or 24 times a day. In 

the summary table (Table 6.6), the hourly solar radiation file 

was used to monitor the ASR CAMS. The hourly C02 data 

and calibration files were used for the C02 CAMS. The 

count of hourly meteorological data file was used for the 

meteorology and ozone M03 CAMS. 
Prevailing wind 

direction 

Average wind 

speed (ms ·1) 

Maximum wind 

speed• (m s·1) 

Direction of max. 

wind• (deg.) 

Average slation 

pressure (hPa) 

Maximum pressure• 

(hPa) 

Minimum pressure• 

(hPa) 

Average air 

temperature ("C) 

Maximum 1emperature• 

('C) 

Minimum temperature• 

('C) 

Average dewpoint 

tcmperalure ('C) 

Maximum dewpoint 

temperalure ('C) 

M inimum dewpoint 

temperature ('C) 

Prccipiation (mm) 

Preva ii ing wind 

direction 

Average wind 

speed (ms ·t) 

Maximum wind 

speed• (m s·

1) 

Direction of max. 

wind• (deg.) 

Average station 

pressure (hPa) 

Maximum pressure• 

(hPa) 

Minimum pressure• 

(hPa) 

Average air 

temperature ('C) 

Maximum temperature• 

('C) 

Minimum temperature• 

('C) 

Average dewpoint 

temperalure (' C) 

Maximum dcwpoint 

temperature ('C) 

Minimum dcwpoint 

temperature ('C) 

Precipitation (mm) 

TABLE 6.3. MLO 1990 Monthly Climate Summary 

Jan. Feb. March April May June July Aug. Sept Oct Nov. Dec. 1990 

Night 

SSE WSW SSE SSE SSE SE SSE SSE SSE SSE SSE SSE SSE 

5.9 7.1 5.3 4.3 4.2 5.8 3.9 3.8 3.5 3.5 4.3 6.3 4.8 

IS 16 13 10 14 13 13 13 10 10 16 16 16 

ISO 206 237 IS4 !SI 138 IS7 14S 157 239 204 21S 21S 

678.S 678.2 679.8 680.0 680.S 681.3 68 1.0 681.6 681.2 681.3 680.0 678.6 680.2 

m m m ~ w w ~ w ~ ~ m m w 

673 672 674 676 678 678 678 679 679 679 676 672 672 

3.S 2.0 3.4 4.9 5.4 7.2 5.2 6.5 5.8 5.5 5.1 2.8 4.8 

9 8 10 12 11 13 12 14 11 10 9 8 14 

-2 -3 -5 -2 2 -I 2 2 2 -2 - 5 

-10.5 -13.4 - IO.I -12.0 - 13.4 -13.5 -8.2 -8.0 -5.3 I 1.2 - 1.7 -5.5 -9.6 

6 4 4 4 6 7 7 7 7 9 8 11 II 

-32 -30 -25 -26 -29 -28 - 35 -30 -21 -27 - 19 -26 -35 

0 0 0 0 4 14 27 19 9 0 0 0 73 

Day 

SE SW SSE NW 1'.'NE SE N NNE N NNW SSE SSE SSE 

5.4 7.5 4.8 4.3 4.5 5.5 3.7 4.1 3.5 3.4 3.9 6.0 4.7 

19 15 16 9 14 14 10 12 9 9 15 17 19 

164 230 236 145 151 149 146 155 137 114 201 148 164 

678.3 678.2 679.9 680.1 680.7 681.5 681.3 681.6 681.2 681.3 680.0 678.3 680.2 

673 672 673 675 678 678 679 679 679 679 675 672 672 

6.8 5.7 8.2 9.7 10.7 12.3 9.9 11.7 10.0 9.4 8.1 6.1 9.1 

15 13 15 17 16 18 16 18 14 14 13 13 18 

-2 -3 -2 - I 3 4 2 3 3 2 2 - 1 -3 

- 7.6 -9.6 -6.3 -6.1 -S.5 -6.7 - 1.8 -2.2 - I.I -1.5 -2.6 -2.7 -4.0 

7 6 7 8 7 9 9 9 9 9 10 18 18 

-31 -28 -25 -29 - 28 -22 -32 -26 -23 -25 -17 -24 -32 

146 100 9 3 0 21 18 34 17 125 59 533 

Instrument heights: wind, 8.5 m; pressure, 3403 m (MSL); air temperature, 1.7 m; dewpoint temperature, 2.0 m. Wind and temperature instruments 

are on a tower IS m southwest of the main building. 

*Maximum and minimum values are hourly averages. 

59 
TABLE 6.4. SMO 1990 Monthly Climate Swnmary 

Prevailing wind 

direction 

Average wind 

Jan. 

SE 

6.0 

14 

115 

Feb. 

s 

7.2 

30 

341 

March April May 

SE SE SE 

6.7 5.6 6.2 

14 13 12 

322 11 5 102 

June July Aug. Sept. Oct. Nov. Dec. 1990 

SE s SE SSE SSE SE SSE SE 

6.9 5.5 6.5 5.5 5.3 6.4 5.8 6.2 

14 12 11 13 15 14 17 30 

12 1 138 134 136 155 326 116 341 

speed (m s -1) 

Maximum wind 

speed* (m s·I) 

Direction of max. 

wind* (deg.) 

Average stalion 

pressure (hPa) 

Maximum pressure• 

(hPa) 

998.8 997.7 1000.2 1001.2 1002.0 1002.1 1002.5 1002.8 1002.7 1002.2 998.4 999.2 1000.8 

Minimum pressure• 

(hPa) 

Average air 

temperature ("C) 

Maximum temperature• 

("C) 

Minimum temperature• 

('C) 

Average dewpoint 

temperature ('C) 

Maximum dewpoint 

temperature ("C) 

Minimum dewpoint 

temperature ('C) 

Precipitation (mm) 

1003 

992 

27.2 

31 

23 

23.9 

25 

21 

209 

1005 1005 

979 996 

26.9 27.1 

31 30 

23 23 

23.3 24.1 

25 26 

20 21 

318 226 

1006 1005 1006 

998 998 998 

26.8 27.3 26.8 

31 32 33 

21 23 24 

24.0 23.6 23.2 

26 25 25 

19 20 20 

333 50 157 

1008 1006 1006 1005 1004 1004 1008 

996 999 1000 999 992 994 979 

26.3 26.2 26.8 27.3 27.1 27.3 26.9 

32 30 33 33 31 32 33 

23 23 22 23 23 22 21 

21.6 21.5 22.6 23.2 23.6 23.1 23.2 

24 24 25 27 26 25 27 

18 16 18 20 20 19 16 

68 37 99 139 266 234 2136 

Instromcnt heights: wind, 13.7 m; pressure, 30 m (MSL); air temperature, 9 m. Wind and temperalllre imtniment< are on Lauagae Ridge, 110 m 

northeast of the main building. Pressure sensors are in the main building. 

•Maximum and minimum values are hourly averages. 

SAMOA 

1990 

.• .: 

I . 

.. ~· 

/ ..... 

,.-.. ·-

....... 

' -················t · ·----... 

.......... - -· t.--·-

i 

··-r-------. _..,...,,..- -·· ---: ··---

...... ··+--.... 

f·-·1 ._,{.." 

\ 

\. 

' ........... ·· 

>~ .... " -"· .... _ !-----~~ .... WIND SPEED (11 /S) 

... ,,. ··...._ 

/ 

• - _ _j_,_.-r • 

: -- ~----

.. .... ___ !_______ _ 

~ .. WIND ROSE 

·· .... 

\ / \ '., \ \ 

j 

i 

/ / 

)t> < _/J! _ .. ·· · ... -- _,,..-· 

·· .... ~-··· 

--5,1fS<5 

.:=5 ' ws < 10 "· 

c=::::J WS ~ I 0 

··----.. ····-____ i __ -~· · .. ~....... I ,.. .. 

·-·--· ·-----~ 111ND FREQ 

,; 

SAMOA 

1977-89 " 

w 

_ .. ··· 

; I t / 

''

/ I - .· ! ; 

'

/ ! 

! :·--···f ; i 

l \ 

\ 

· .. , ..... _ 

>< .. / · ..... 

WltlD SPEED (11/S) 

--5S WS<5 

=s s ws < 10 

ws ~ 10 

~ .. _ 

" ' .......... . . " WIND ROSE 

...... .. -· .-···· r---... _ _...... -·· ···--··I --.. ·-.. ---1·--.... i -r-··-··-- ..i ..... 

I 

' 

,..'( .. 

' "'°' 

_/ \ \ · ... \ \ \ .\ 

\ \., \ \ \ i \ 

.l .... ; ..J -B 

J ! ! 

I I I 

/ 

./ 

111ND FREQ 

:: 

j 

Fig. 6.4. Wind roses of the surface wind for SMO for 1990 (left) and 1977-1989 (right). The distribution of the resultant wind direction and speed are 

in units of percent ocairrence for the year and 13-year period, respectively. Wind speed is displayed as a function of direction in three speed classes. 

60 
Prevailing wind 

direction 

A vcrage wind 

speed (m s -

1) 

Maximum wind 

speed• (m s·1) 

Direction of max. 

wind• (deg.) 

Average stat ion 

pressure (hPa) 

:.1aximum pressure• 

(hPa) 

:.tinimum pressure• 

(hPa) 

Average air 

temperature ('C) 

Maximum temperature• 

('C) 

.\1inimum temperature• 

('C) 

A vcragc Dewpoint 

temperature ('C) 

Maximum dewpoint 

temperature ('C) 

Minimum dewpoint 

temperature ('C) 

TABLE 6.5. SPO 1990 Monthly Climate Summary 

Jan. Feb. March April May June July Aug. Sept. Oct. Nov. Dec. 1990 

N E.'\E ENE ENE E NNE NNE NNE NNE N ?'\'>ill N K:'\'E 

4.6 4.8 5.3 5.4 5.0 7.8 6.7 5.9 6.9 6.4 6.4 5.8 5.9 

10 9 9 12 10 15 14 13 13 14 13 II 15 

330 312 17 13 98 12 13 13 360 3 356 344 12 

688.3 681.3 680.6 685. I 684.5 681.2 681.5 674.6 666.7 678.6 685.2 689.1 68 1.4 

699 689 69 1 7 15 707 695 694 694 688 701 700 699 7 15 

677 670 671 668 668 668 658 661 65 1 662 676 674 65 1 

-26.8 - 40.6 -57.1 -58.7 -60.6 -55.6 -56.9 -(J().9 - 58.1 -49.0 -35.4 - 23.8 -48.4 

- 19 -30 -38 -39 -39 - 40 -40 -45 -36 -33 - 19 - 19 - 19 

-35 -49 -70 -74 -71 -69 -75 -74 -76 -64 -51 -29 -76 

-27.7 -42.9 t t t t t t t t -38.6 -25.2 -49.3 

- 19 -32 t t t t t t t t -25 -20 - 19 

-36 t t t t t t t t t t -41 -41 

Instrument heights: wind, 12.2 m; pressure 2841 m (MSL); air temperature, 2.2 m. The anemometer and thermometer are on a tower 100 m grid 

cast-southeast of CAF. Pressure measurements arc made inside CAF. 

•Maximum and minimum values are hourly averages. 

t Missing data 

SOUTH POLE 

1990 

I 

! .1 

/ ! / 

j 

v¥. . ·-( ·--1--r .... f ... i : 

\ i \ \, \ \ \ 

--5 S< 5 

=:zll5 ~ WS < 10 

WS ~ 10 

........ 

..... 

i 

~··•• ··-· •·-· 

~ \ \ 

/ 

WIND HOSE 

"· ... 

\. 

' .... 

\ 

\ 

/ //I ! 

/ 

,;/ ./ / ....... /" / / .l 

........ ·· 

WlND FREQ 

T. 

SOUTH POLE ..... 

1977 - 89 ....... · 

_ ... ~ 

,,,.. ....... .. . . '...... ,,. . .. .. ··· ... ,.."' 

;' ~·'/ .·· "'· ... 

I _I 

l/11 / .... /, ... 

: ! ;" i : . :/ 

W. .. 1

1

'_.

1

• --t_;

1

. ___ L_rt ·--L- 1··· 

! \. \ \ \ \ 

\ \. 

' 

-····-· ··--··- ...... . 

I 

......... I ... --........... __ . --· : ·- -... 

WIND ROSE 

WUID r REQ 

!\ 

Fig. 6.5. Wind roses of the surface wind for SPO for 1990 (left) and 1977-1989 (right). The distribution of the resultant wind direction and speed are in 

units of percent occurrence for the year and 12-year period, respectively. Wind speed is displayed as a function of direction in three speed classes. 

61 
TABLE 6.6.a CMDL CAMS Operations Summary, 1990 

Blocks Recorded and [Blocks Missing) 

Block Expected No. of 

Type Description Blocks 1990 BRW MLO SMO 

A Hourly aerosol data 2190 2170 [20) 2179 [II) 2178 (12) 

B Secondary aerosol data 2190 1924 2090 o• 

H Daily aerosol data 365 361 (4) 364 [I) 363 (2) 

s Hourly solar radiation data 8760 8681 (79) 8714 (46) 87 12 (48) 

T Daily solar radiation data 365 343 [2) 363 (2) 363 (2) 

c Hourly C02 data 8396t 8292 [98) 83 16 (58) 6416 (2042) 

D Daily C01 data 365 362 (3) 365 (0) 279 (86) 

E Hourly C01 calibration data 364:1: 355 343 297 

F C02 calibration report 52 51 49 41 

M Hourly meteorological data 4380 4377 [4) 4369 (11) 4377 (3) 

0 Daily surface ozone data 365 365 [0] 365 (0) 365 [0) 

w Daily meteorological data 365 365 (0) 365 (0) 365 (0) 

I Meteorological calibration 365 365 (0) 364 [I) 365 (0) 

N Surface ozone calibration 52 54 56 56 

TABLE 6.6.b CMDLCAMS Operations Surrunary, 1990 

Expected No. of 

Individual CA.i\4S Blocks 1990 BRW MLO 

ASR 8760 99.10% [79) 99.47% (46) 

co1 8760 98.71 % (113) 98.85% (IOI) 

M03 4380 99.93% (3) 99.75% [II) 

Total 21900 99. 11% [195] 99.28% [158) 

•Secondary aerosol channels are not used in Samoa 

tNominal block count equal to total hours in year less 52 7-hr calibration periods. 

:!:Nominal block count equal to 52 7-hr calibration periods. 

Percent Data Capture 

SMO 

99.45% (48) 

76.63% [2047) 

99.93% [3] 

90.42% (2098] 

SPO 

2157 (33) 

2158 

361 (4) 

8634 (126) 

360 (5) 

8260 [II) 

365 [0) 

490 

69 

4286 (94) 

358 [7) 

358 [7] 

357 [8) 

5 

SPO 

98.56% [126) 

99.89% [10) 

97.85% (94) 

98.95% [230) 

Due to the remoteness of the observatories, power 

outages are common occurrences. This has been the case at 

SPO as the load on the generators has increased to capacity 

during recent years. If the board that restarts CAMS after 

power failures is operational, the amount of data Joss is 

confined to the time o f the outage. This board failed and 

was replaced in the ASR and M03 CAMS at BRW. A 

memory and clock board were replaced at SMO; a memory 

board was repl aced at SPO. The five boards that failed 

constitute about 4% of the system's complement. 

files by block type rather than by the individual CAMS 

hardware it was recorded on. Data files are smaller and 

faster to access than before. All CAMS data from previous 

years (1984-present) were translated to the new file format. 

All such data are stored on the CMDLN AX computer. 

During 1990, the CAMS data processing software was 

completely rewritten. The data is now stored on indexed 

62 

6.2. REFERENCE 

DeLuisi, J.J. (Ed.), Geophysical Monitoring for Climatic Change, 

No. 9: Summary Report 1980, 163 pp., NOAA Environmental 

Research Laboratories, Boulder, CO, 1981. 
7. Nitrous Oxide and Halocarbons Group 

W.T. STURGES (Editor), T. BARING, J. BUTLER, J.W. ELKINS, B.D. HALL, R.C. MYERS, S.A. MONTZKA, 

T .H. SWANSON, AND T .M. THOMPSON 

7 .1. CONTINUING PROGRAMS 

7 .1.1. FLASK SAMPLES 

Air samples continued to be collected in pairs during 1990 

and analyzed for CFC-12, CFC-11, and N20 concentrations. 

Samples were collected from the CMDL baseline stations 

BRW, MLO, SMO, and SPO with the addition of Niwot 

Ridge (NWR), Colorado (see Section 7.1.2) and Alert, North 

West Territories (ALT). Higher pressure pumps (3 atm) 

were deployed at BRW, MLO, and SMO in late February to 

early March so that sufficient sample volume would be 

available for both the LEAPS and flask projects. NWR 

received the pump in July. SPO personnel used the new 

pump in 1989 and continued its u se during 1990. ALT will 

be upgraded in 1991. 

The new automated flask-analysis system was tested 

extensively throughout the year. Intercomparisons of flask 

and calibration tank results were made between the new and 

old GC systems. The two systems gave consistent results 

with no systematic differences. Routine flask analyses with 

the new system should begin in 1991. 

The time series of monthly mean N20 concentrations has 

been extended another year in Figure 7 .1. Likewise, updated 

CFC-12 and CFC-11 data are shown in Figures 7.2 and 7.3. 

320 

310 BRW ., 300 

Slo e = 0.61 +· 0.04 ppb yr-1 

:0290 

NWR .. §:310 -. ·. ,. 

--c: 300 . . .9 290 

Slo e = 0.65 +· 0.05 ppb yr-1 

...... MLO i:: 310 ...... . .. 5 300 ·- u S lo e = 0.67 +· 0.04 ppb yr-1 

c: 290 

0 SMO u 310 

0 300 ,., . , . N " S lo e = 0 .72 +- 0.06 ppb yr-1 z 290 

310 SPO 

300 . 290 

S lo e = 0.66 +- 0.07 ppb yr-1 

77 78 79 80 81 82 83 84 85 86 87 88 89 90 

Time (year) 

Fig. 7. 1. Monthly mean concentrations of N20 (C02 and H20 

corrected) from the CMDL flask sample network. The trends and 

95% confidence intervals are also shown. 

+::"475 

0.400 

BRW 

0.325 

..._.. so+--+-+---+--+-+---+-S_lo+-e-=~1_5~.2_;_++-~0.~3~p~p~t~y~r-+1--1 

c: 475 

.Q 400 

NWR 

-ctS 325 Slo e = 15.4 +- 0.3 ppt yr-1 .!::: 250 -t--+-+---+--+-+---+--4--+---+--+~.,:.;.::~.;...+--I 

c: 475 

<l> 400 

(J 325 § 250 -t--+-+---+--+-+---+-s_10+--=~1_4~.7-•+-~0.~3~p~p~t~y~r-+1--1 

U 475 SMO 

400 

C\I 325 ,- = 15.5 +· 0.2 ppt yr-1 I 250+--+-t---+--+-t---+--+-t---+--+-jo!..!..+:--;---I Slo 

u 475 

LL 400 

u 325 

SPO 

250 77 78 79 80 81 82 83 84 85 86 87 88 89 90 

Time (year) 

Fig. 7.2. Monthly mean dry concentrations of CFC-12 from the 

CMDL flask sample network. The trends and 95% confidence 

intervals are also shown. 

63 

300 

+::"250 BRW 

0.200 

0.150 Slo e = 9.6 +· 0.1 ppt ..._.. 

c: 100 NWR 0 250 

·- 200 -

ca 150 S lo e = 9.5 +· 0.1 ppt r-1 .!::: 100 

c: MLO 250 

<l> 200 

(.) 150 S lo e = 9.6 +· 0.1 ppt r-1 c: 100 0 u SMO 250 

200 

,.. 150 ,.. S lo I 100 

u 250 SPO 

LL 200 

u 150 Slo e = 9.4 +· 0.2 ppt r-1 

100 77 78 79 80 81 82 83 84 85 86 87 88 89 90 

Time (year) 

Fig. 7.3. Monthly mean dry concentrations of CFC-I I from the 

CMDL flask sample network. The trends and 95% confidence 

intervals are also shown. 
ALT flask sample concentrations, which have now been 

measured for 3 years, are plotted in Figure 7.4. The 

incidence of inconsistencies between flask pairs decreased 

considerably at ALT in 1990. 

The long record of BRW data has been analyzed for 

seasonality by removing the trend and fitting a locally 

weighted spline to the residuals. CFC-12, CFC- 11, and Np 

all exhibit the same seasonal cycle (Figure 7.5) with higher 

concentrations in the November-February period and lowest 

values during May through August. This is typical of many 

pollutants measured in the Arctic Basin. A cold stable air 

mass develops in winter, bounded by the arctic front, with 

limited loss mechanisms from advection, mixing, deposition 

and photochemistry. Concentrations grow from periodic 

injection of polluted air masses originating at midlatitudes. 

N s20-+-~~~~~~.._~~~~~ ..... ~~~~.~__.j 

• • • ·~·~·#4'6'='···~ •••. -~-~ ,_, 

. . ........ , .. ~ .... . , .... . . ~·.·"-·# ·"' .. 

u 490-

b 460 b - 320-+-~~~~~~i--~~~~~ ..... ~~~~~--..j 

. - • ........ , ........... ~•·,.~,,,,..-Jo"'-"' . A& ..... ~ J.. .................. - c 

1989 1990 

Fig. 7.4. Flask sample concentrations for (a) N20, (b) CFC-12, and 

(c) CfC-11 at Alert, North West Territories. The dashed lines are 

spline fits to corresponding BRW flask sample data, for comparison. 

' u 

I.I. 

u 

0 

·5 

·

10 77 78 79 80 81 82 83 84 85 86 87 88 89 90 

Fig. 7.5. Spline fit showing seasonal variability in the residuals of 

(a) 0, (b) CFC-12, and (c) CFC-I I flask concentrations at BRW. 

7.1.2. RITS CONTINUOUS GAS CHROMATOGRAPH 

SYSTEMS AT CMDL BASELINE STATIONS 

In situ sampling of air continued at BRW, MLO, SMO, 

and SPO. Twenty-four analyses of N20, CFC-12, CFC-11, 

CFC-113, methyl chloroform and carbon tetrachloride were 

made every day at each station . 

In February a new continuous gas sampling system was 

brought on line at NWR. The system is a duplicate of the 

GC systems at BRW, MLO, and SMO. The NWR site 

provides the group with continuous monitoring of nitrous 

oxide and halocarbons at the same site used to fill working 

calibration cylinders. The GC system is located in an 

air-conditioned unit at site C-1 of the Mountain Research 

Station, Institute for Arctic and Alpine Research 

(INST AAR), University of Colorado. C-1 is located at 

40'2'N, 105'32'W and is at an altitude of 2027 meters (9900 

feet). NWR is the group's only interior continental site and 

provides a unique platform to analyze continental air 

composition. In addition, it provides a field site for testing 

hardware and software before installation at other, more 

remote, sites. 

In 1990 significant improvements were made to the GC 

network. During the first quarter the sampling and analysis 

frequency was increased to once every half hour. This 

resulted in a significant improvement in precision, due to the 

decrease in lag time between sample and calibration runs. 

The increased frequency was achieved by the addition of an 

eight-port stream selection valve, which permits two air 

samples to be analyzed per rotation. 

An upgrade of the hard drives at the stations from 15 

megabytes to 20 megabytes allowed the addition of new 

software at each station. This included RITSPLOT, a 

program developed by the group, and installed at the stations 

in November. RITSPLOT is a complete package of plotting 

and database management routines written in HP-BASIC. It 

calculates preliminary concentrations after every air-sample 

run and updates a database containing 1 month of concentration values. A key feature of RITSPLOT is that it is 

accessible by station personnel. With a single keystroke they 

are able to view the previous month's data and assess the 

system performance. This should prove invaluable in 

troubleshooting. 

Access to RITSPLOT was made via a new version (v. 5.1) 

of the NOAA data acquisition software installed in 1990. 

This allows RITSPLOT to be run without affecting the data 

collection functions of the system computer. It also has 

improved error handling capabilities and a routine to store 

preliminary concentration data in IBM-compatible ASCII 

format on a 720-kilobyte, 3.5-in. floppy disk for easy 

transfer to the station PCs. Two 1.44-megabyte ciata 

diskettes now provide room for 1216 files. Each diskette is 

filled with raw chromatographic data approximately every 4 

days for return to the Boulder office. 

64 

To accommodate the increase in raw data received from 

the stations, consolidation of the processing programs at the 

Boulder office was implemented. Ten programs were 
consolidated into four: (1) catalog and back-up incoming 

data diskettes; (2) reprocess raw chromatograms for area and 

height data; (3) calculate concentration values; and (4) plot 

data for visual quality control applications. The reduced 

data is stored on the group's UNlX network hard drive where 

it is available to all the group for statistical analysis. 

The 3.5-year record of daily average N20 concentrations 

from the in situ GCs at BRW, MLO, and SMO is shown in 

Figure 7.6. The armual cycle at BRW can be best seen in the 

1990 data set, with a maximum in February and a minimum 

in August. This also illustrates the improvements brought 

about by the increased precision due to the higher sampling 

frequency. During 1989-1990 the armual growth rate was 

approximately 0.6 ppb yr1 at all stations. 

Daily average CFC-12 concentrations are shown in Figure 

7 .7. The annual increase remained at 19 ppt yr1 for all three 

stations. CFC-11 daily average concentrations for BRW, 

MLO, and SMO are shown in Figure 7.8. The CFC-11 data 

confirm the cyclic nature of CFCs at BRW. Again, the 

improvements in precision in 1990 are evident, particularly 

at BRW. CFC-11 measurements from SMO before March 

1989 were extremely noisy and have not been plotted. 

Annual growth rates at BRW, MLO, and SMO were about 

7 .5 ppt yr· 1, which is low compared to the flask data. The 

study period, however, is short, and experimental and 

calibration errors are still relatively large. A proper 

intercomparison of the flask and continuous data is, 

therefore, not possible at this stage. 

Daily average carbon tetrachloride (CC14) concentrations 

are shown in Figure 7.9. The concentrations were nearly 

constant in 1990. 

312 

308 ,...... 

.0 

0..304 0.. 

'-' BRW 

§ 312 

·;:i 

CIS 

~ 308 '>·; ... ::· .. ;; ..... .; c 

0 : . : : .. · .... u 

c 304 

0 MLO u 

0 312 

N 

z 308 ... 304 SMO 

300 

1987 1988 1989 1990 

Fig. 7.6. Daily average N20 concentrations at BRW, MLO and 

S:v10 obtained from the in situ GCs. The trends were generated 

using least squares regression analysis. 

-.... 

C.500 

c. 

-c: 450 

0 

·-co 550 ,_ 

.... 

c: 500 

Q) g450 

0 

BRW 

MLO 

(.)550-l-++++++4++-1-++-H++-++H++++++-1-+-HH++-+++++++++ 

CN 

,.... 500 I 

(..) 

u.. 450 

(..) ... ... 

1987 1988 

• > , 

SMO 

1989 1990 

Fig. 7.7. Daily average CFC-12 concentrations at BRW, MLO and 

S:v10 obtained from the in situ GCs. The trends were generated 

using least squares regression analysis. 

During 1990 SMO station had a large number of power 

outages and brownout conditions. The computer equipment 

that controls the sampling sequence and stores the data was 

protected by an uninterruptible power supply (UPS). The 

GCs, because of their high power load, were not protected. 

c: 240 

0 BRW 

CO 300-t-+++-+-HH-+++-1-H-++++-1-H++-+-HH-+++-1-H++-+-HH-+++-H ,_ 

.... 

c: 270 

Q) 

g 240 

0 

~ .. · .. '-

MLO (.)300-t++++-++-t-++++-+-++-t-+++-l-+-+-HH++++~-++-H-+~..............-

,.... 

"7 270 

(..) 

u.. 240 

(,) 

• I I 

SMO 

210........._ ................................................................................................................................................................. .......J 

1987 1988 1989 1990 

Fig. 7.8. Daily average CFC-11 concentrations at BRW, MLO and 

S:v10 obtained from the in situ GCs. The trends were generated 

using least squares regression analysis. 

65 
-... 

0.. 

110 

~ 100 

c:: BRW .2 120;--+~-+--+~-+--+~-+---+-~+---+-~+---+----I 

~ c:: 110 Q) 

u 

g 100 

u MLO 

...:! 120-r-~+--+~-+-~+-__,t---+~-+-~+--+~-+-~+---I 

u 

u 110 .... I"'\._,._..,~------... -... ,_,_--.,,....,., 

100 

SMO 

1990 

Fig. 7.9. The 1990 daily average carbon tetrachloride (CCl4) 

concentrations at BRW, MLO, and SMO obtained from the in situ 

GCs. 

An analysis of the N20 data shows a diurnal vanatton 

(Figure 7.10) that could be due to these variations in line 

voltage to the GCs. Nine months of data were fitted with a 

spline to remove trends and seasonality. The residuals were 

then grouped by hour of the day and the mean and 95% 

confidence interval calculated. At 0400 GMT (1700 LST), 

N20 concentration dropped for a few hours, rose 

dramatically, then dropped back to normal over the 

following few hours. This period corresponds to the daily 

increase in domestic power supply at the end of the working 

day, resulting in voltage fluctuations observed at the station. 

In 1991 a large UPS will be installed to condition the GC 

equipment power and a similar analysis will be done to see if 

........ 

.0 SMO 

0.. 

0.. ..._. 0.5 

...... 

~ 

;:l 

"O 

..... 

Vl 0 0 

~ 

0 <'I 

z -0.5 

0 2 4 6 8 10 12 14 16 18 20 22 24 

GMT 1990 

Fig. 7.10. Residual N20 concentrations at SMO during 1990 

averaged for each hour of the day. The bars show the 95% 

confidence intervals. 

the N20 variation diminishes. Similar variations were not 

observed in the CFC measurements. 

7.1.3. LOW ELECTRON ATTACHMENT POTENTIAL 

SPECIES 

Routine flask sampling and analysis of LEAPS gases 

began in mid-1989. Despite some instrumental down-time, 

we now have a relatively continuous record spanning 1.5 

years. HCFC-22 measurements began in mid-1990. 

Procedures have been developed to measure HCFC-22 and 

the other LEAPS and CFC gases in the same sample by 

connecting two electron-capture detectors in series and 

doping the carrier stream with 0 2 to 0.2% before the second 

detector. This enhances the HCFC-22 peak measured by the 

second detector while the adjacent, and potentially 

interfering, CFC-12 peak is reduced during passage through 

the first detector (Figure 7.11 ). Halon (brominated CFC) 

measurements have been made without serious problems. 

Although the data set spans only 1.5 years, some trends are 

already apparent. Data from the four CMDL observatories 

show a significant rate of growth for H-1301 (Figure 7.12a). 

The rate of increase varied among stations from 0.26 to 0.47 

ppt yr1, with a mean of 0.36 ppt yr·1, but the differences 

between these slopes are only marginally significant, owing 

to the short amount of time and relatively small number of 

samples. Mean concentrations at the observatories increased 

with increasing latitude, indicating the importance of 

northern hemispheric sources. 

66 

300 

113 r 1 2 I.IC 

a) 200 

100 

::>-

E 

.., 

...... 300 c:: 

0 

=-...... 

"' °"' u b) 200 .., 

:i:: 

u 

0 

N 

z N 

N 

~ 

~ 

CD 

.., 

:i:: 

u 100 

0 21N2 

0 

4 8 1 2 1 6 20 

Time (min) 

Fig. 7.11. LEAPS chromatograms of air from BRW; (a) N2 carrier 

gas (ECO #1), (b) N2 carrier gas doped with 0 2 to 0.2% (ECO #2). 

The ECOs were connected in series. 
H-1211, unlike H-1301, showed Jillie or no growth at the 

four observatories during this period, and the latitudinal 

gradient was not significantly different from zero (Figure 

7.I2b). Production rates for H-1211 did not decline during 

this time, although release rates may have slowed in 

response to international control agreements and 

environmental considerations [Halon Research Institute, 

1989). A longer sampling record is required to determine 

accurately whether or not there are indeed temporal and 

latitudinal variations in both H-1301 and H-1211. 

7 .1.4. GRA VLVfETRIC STANDARDS 

A total of 36 primary calibration standards were prepared 

during 1990 for use in the RITS , LEAPS, and special 

projects. A summary is given in Table 7 .1. The total 

number of primary standards on the NOAH inventory was 

223 at the end of 1990. Of these, 122 were prepared in our 

own standards laboratory. Twenty-five cylinders were filled 

a. 

a. 

.... 

>-

.... 

Cl 

c 

0 

0 

a::: 

Ol 

c 

·-)( 

2.0 

1.5 

1 .0 

2.5 

2.0 

a) 

• • 

'-•···--:·J.· .... >·' .......... ---~~ ~· . .: -:. · .... -... • .... \ ' ••••• .,.~1- .... .:-.-:"··· ........

··...

. 

........ -. . . . .... _ .... ~ -·- " 

b) 

• . " 

..... ·..; :+ :;.· .........•...•.. -ft·-··· ...... .i.. 

1 . 5 •\"·· ...... -+ .... r:.·.-.::::w:..-----.----1 

. -·-·-·- " 

1.0'-:--'-~-'---'~-'-~"'---'-~-'----'~--'---' 89.5 89.8 90 .1 90.4 90 . 7 91.0 

Ye ar 

Fig. 7.12. Concentration trends in (a) H-1301 and (b) H-1211 al 

CMDL observatories from mid-1989 through 1990. The mean slope 

for all H-1301 measurements is 0.36 ppl y- 1• The mean slope of the 

H-1211 measurements does not d iffer significantly from zero. 

Stations are idcntLfied as follows: BRW, circles and solid line; 

?\"WR, squares and dashed line; MLO, triangles and broken dashed 

line; S.'.\10, diamonds and dotted line. 

with air at Niwot Ridge during the year and analyzed for use 

as secondary standards at the field sites and in the 

laboratory. 

7.2. SPECIAL PROJECTS 

7 .2.1. ALTERNATIVE HALOCARBON MEASURD1ENTS 

It is anticipated that by the year 2000 most CFCs will 

have been phased out, partly by substitution with two 

alternative families of compounds: HCFCs (hydrochlorofluorocarbons) and HFCs (hydrofluorocarbons). 

Both break down more rapidly in the atmosphere, and 

therefore have lower ozone depletion and global warming 

potentials. Apart from HCFC-22, which is already in 

production, the "alternative halocarbons" are not currently 

present in the atmosphere. They present a three-fold 

challenge to their analysis: very low atmospheric 

concentrations for at least the next two decades, poor 

sensitivity with the electron capture detectors (ECDs) that 

NOAA presently uses to routinely measure CFCs, and 

similar physical properties to the CFCs that they replace, 

making their chromatographic separation difficult in some 

cases. 

Beginning in October 1990, we began work to develop 

techniques for alternative halocarbon measurements and 

concentration of air samples using adsorbent traps. Initially 

we are focussing on HCFC-22, HCFC-123, and HFC-134a. 

We have been unable, as yet, to obtain standards for 

HCFC-14l b, another important alternative halocarbon 

candidate. 

67 

GC!Mass Spectrometer Analysis 

An HP 5971A GC interfaced to a mass spectrometer 

detector (GC/MS) was purchased by the NOAH group to 

address some of the difficulties involved in measuring 

alternative halocarbons in the atmosphere. This instrument 

can sensitively detect a much wider variety of compounds 

than the ECD. For example, HFC-134a contains no chlorine 

atoms and, therefore, has almost no ECD response. 

HCFC-22 does contain chlorine atoms, but is weakly 

electrophylic and is two to three orders of magnitude less 

sensitive by ECD than CFC-12. Sensitivity of the GC/MS, 

however, is nearly equivalent for HFC-134a, CFC-12 and 

HCFC-22 (Figure 7.13a). HCFC-123, a proposed 

replacement for CFC-11, is also sensitively detected by 

GC/MS and can be easily separated from CFC-11 (Figure 

7.13b). By collecting 1-10 dm3 of air for a single analysis 

we expect to be able to detect <1 pptv of alternative 

halocarbons such as HFC-l 34a in air. This will be 

accomplished by either cryogenically concentrating air 

contained in cylinders or by using adsorbent tube 

pre-concentration techniques. 

The GC/MS can be operated in either a full scan mode, 

with a wide range of compound sensitivity, or in a highly 

selective "single ion mode" (SIM). SIM enables 

quantification of coeluting compounds and also provides 

greater sensitivity for the selected species. Although the 
Table 7.1. Summary of Gravimetric Standards Prepared in 1990 

Compounds Quantity 

N20 6 

CFC-12 2 

CFC-I I 2 

CFC-11 , CH3CC!3, CC14 7 

C6I\ 2, C7Fw C8F16, C9F18 4 

CfC- 11, CFC-11 3, CH3CC13, CC14 5 

CFC-I I, CFC-12, CPC-1 13, CH3Cl, CH3CC13, CC14 3 

CfC-11, CFC-113, Cil3CCl3, CCl4 6 

Ilalon -130 I 

compounds presently under study have been successfully 

separated chromatographically, SIM may prove invaluable 

for other alternative halocarbons. 

Because of its wide-range sensitivity and ability to 

identify unknowns from their ion spectra, the GC/MS will 

also prove useful in checking our gravimetric standards for 

purity. It will also be used to investigate contamination 

problems with sample and standard tariks; for example, 

acetaldehyde has been identified as a contaminant in one of 

our gravimetric standards, possibly originating from a 

sealing compound in the pressure fittings. 

Adsorbent Tube Pre-Concentration 

A large number of materials, including chromatography 

packing materials, carbon molecular sieves, and activated 

carbons, have been screened for their potential use as 

adsorbents to concentrate CFCs and alternative halocarbons 

l......J 

<:....:> 

= 

JOOO 

-ex: 2000 

= = 

= 

~1000 

= = 

l......J 

<:....:> 

0 

J. 7 5 

1000 0 

HFC- 1340 {o) 

CFC-12 

HCFC - 22 

"75 • . 75 5. 25 5 . 75 

(b) 

~ CFC-11 

HCFC- 123 

::Z- IOCOO 

= = 

-ex: 

= 

= 0 

I 2 .5 I J IJ.5 14 14 . 5 15 RETEN TI ON T I ME ( m;n) I 5.5 

fig. 7.13. Reconstructed selected ion chromatograms of (a) 

HfC-134a (1.3 X 10·10 dml), HCFC-22 (1.1 X 10-11 dml), and 

CFC-12 (2.4 X 10-11 dml), and (b) HCFC-123 (I.OX 10-10 dml) and 

CfC-1 1 (1.0 X 10-10 dm3). Sample volumes are vapor phase 

volumes at STP. 

Concentration Range 

ppm, ppb 

pp! 

pp! 

ppm, ppb, ppt 

ppm, ppb, ppt 

pp! 

ppt 

ppb, ppt 

pp! 

Prepared for 

NOAA/RlTS 

NOAA/RlTS 

NOAA/RlTS 

NOAA/RlTS 

NOAA/ARL 

NOAA/RlTS 

NOAA/RlTS 

NOAA/RlTS 

NOAA/LEAPS 

from large volumes of air. This presents a significant 

challenge since the compounds we wish to collect are 

considerably more volatile, and therefore less easy to trap, 

than compounds normally collected with adsorbent tubes. 

We now have several alternative designs for multi-stage 

traps (see example in Figure 7 .14 ). After sampling, trapped 

compounds are desorbed by heating the tube while 

backDushing with nitrogen. The compounds are then 

cryogenically reconcentrated at the head of a GC capillary 

column for analysis. 

68 

Adsorbent tubes offer a number of advantages over flask 

sampling. Due to their small size we will be able to produce 

a hand-portable microcomputer-controlled 32 tube sampler 

and desorber. Designs have also been made for an automatic 

aircraft sampler-desorber-GC analyzer. Tubes can be used to 

concentrate greater volumes: as much as tens of dm3 

compared with approximately 2.5 dm3 for the largest flasks 

used in our sampling network. This is valuable where 

detection of ultra-low concentrations is required, or where 

less sensitive techniques such as GC/MS are employed. 

I -e- 0.635 cm OD nickel tube 

SAMPLE ------t~ 

------- DESORB 

24cm 

.. Gem .. .. 4cm ... 1ocm •~cm., 

CFC-113+ CFC·l 1 CFC-12 

12] Glass wool packing HCFC-123 

Tenax TA Poropak Q 

HCFC-22 

HFC-134a 

Carbosleve S·ll 

Fig. 7 .14. Example of three-stage adsorbent trap designed to collect 

key CFCs, HCFCs and HFCs with high efficiency from 15 dm3 of 

air at a flow rate of 50 cm3 min·l, and desorb aU trapped compounds 

within 5 minutes at 220"C. 
Most compounds arc very stable on the adsorbents and, since 

the entire tube is desorbed, wall losses should not be a 

problem; thus some of the artifacts that plague flask samples 

may be overcome. The adsorbents selected are hydrophobic 

and other gases such as C02, which may cause cryo-trapping 

and analytical problems, are not collected. Tubes also 

extend the practical limits to in situ GC cryo-trapping; to 

directly cryo-trap the same amounts of air could take more 

than an hour of instrument time and undoubtedly lead to 

peak broadening, sample loss, and column plugging. 

It is planned to send the portable tube sampler to the 

baseline observatories and on aircraft and ocean-cruise 

missions. On return it will be interfaced to the GC/MS 

and/or GC/ECD. Specialized ECD techniques will need to be 

developed, including oxygen doping, halogenation reactions, 

and multiple columns, to improve HCFC sensitivity and 

separation. In the long term, we look to placing real-time 

GC systems in the field to measure alternative CFCs. 

7.2.2. SOVIET-AMERICAN GAS AND AEROSOL EXPERIMEl\T {SAGA III) 

The SAGA III cruise, from February to April 1990, began 

in Hilo, Hawaii, and crossed the equator seven times 

between 2o·N and 15•s before ending in Singapore. 

Automated in situ measurements of N20, CFC-11, CFC-113, 

CH3

CC13, and CC14 in the atmosphere and surface water 

were made at 40-minute intervals. The main objectives were 

to evaluate the spatial and temporal variability of trace gases 

across the inter-tropical convergence zone (ITCZ), trace the 

zonal movement of the ITCZ, determine halocarbon 

saturation anomalies and assess their use in calculating 

air-sea transfer coefficients, measure the flux of N20 from 

equatorial waters, and compare the results at stations 

sampled in 1987, an El Nino year. 

The most significant findings were that CH3CCl3 and CCl4 

were undersaturated in surface seawater for almost the entire 

cruise. Until now the ocean has not generally been 

considered to be a sink for these gases. The air-sea fluxes 

we calculated (Figure 7.15) are supported by recently 

published rates of hydrolysis for the two compounds 

[Geruns and Franklin, 1989; Jeffers et al., 1989]. Our 

results indicate that 5-11 % of atmospheric CH3CCl3 and 

16-35 % of CCl4 are lost to hydrolysis and mixing in the 

world oceans [Butler et al., 1991]. This finding is 

particularly significant to model calculations of tropospheric 

OH concentration based on the lifetime of CH3CCl3, since it 

is presently assumed that CH3CC13 is lost solely by reactions 

in the atmosphere. This suggests that current estimates of 

mean global OH concentration are about 5-11 % too high. 

This in tum implies that estimates of the atmospheric 

lifetimes of some important atmospheric compounds that are 

removed by tropospheric OH, such as CH4, CO, non-methane 

hydrocarbons (NMHCs), HCFCs, and HFCs, are longer than 

previous estimates by about 5-11 %, increasing their global 

warming or ozone destruction potentials by the same amount. 

The utility of CH3CCl3 and CFC-11 as tracers of 

atmospheric circulation was demonstrated on this cruise. 

Both compounds indicated that the width of the ITCZ varied 

from 2• to 20· of latitude, depending upon major atmospheric 

circulation patterns (Figure 7 .16). The concentrations were 

also used to identify an intrusion of northern hemispheric air 

as far south as 14°S. This was later identified from satellite 

photographs as having been associated with a large storm 

system moving southward. 

As expected, N20 was supersaturated in equatorial surface 

waters, with highest saturation anomalies in the east Pacific 

(Figure 7 .17). N20 was found to be the most sensitive 

chemical tracer of upwelling, in agreement with the findings 

of SAGA II [Butler et al., 1988, 1989]. It was also noted 

that atmospheric N20 increased in response to higher 

saturation anomalies in the underlying water, implying either 

stratification within the marine boundary layer or the 

presence of a shallow, stable surface layer retarding vertical 

mixing. This is consistent with observations of C02 during 

SAGA II where atmospheric C02 was found to be lower over 

highly undersaturatcd waters during surface inversion 

conditions. One notable exception to this occurred around 

day 58, when atmospheric N20 increased with the intrusion 

of northern hemispheric air mentioned earlier. 

5.0 - a) -

_: := 1t '1 1n11~11w 111 Hi 1~ 1~r~ ..-..- 10.0-

' -0 

7 -15.0fE 

0 

E 

c 

)( 

:> 1 .0 -

L..... 

-3.0 f-

-

-

-

-5. 0 ~~~-~-~-~·--~~~~~-~ 

20S 15S 10S SS 0 5N 10N 15N 20N 

Latitude 

Fig. 7. 15. Fluxes of (a) CH3CCl3 and (b) CCl

4, calculated from 

saturation anomalies and instantaneous a ir-sea transfer velocities 

from SAGA ill, and plo11ed as a function of latitude. The mean flux 

of CH3CC13 was 3.2 nmol m-2 d-t and for CC14 was 0.95 nmol m·2 

d·'. 

69 
200 

175 a) 

a.. 

a.. + 

~ 150 

,,,~~J~~ u 

u ~ 

::i:: 

u 

1 25 

290 

......., 

a.. 

a.. 28 0 ........, 

I 270 u 

~ 

u 

260 

250 

40 50 60 70 80 90 100 

Julian Day 

Fig. 7 .16. Atmospheric dry mixing ratios of (a) CH3CCl3 and (b) 

CFC- 11 during SAGA III, showing the transition between northern 

and southern hemispheric air masses. 

7 .2.3 . AIRBORKE CHROMATOGRAPH FOR ATMOSPHERIC TRACES PECIES (ACA TS) 

One of the recommendations of the National Global 

Climate Change Program [GCRP, 1989] is that more 

measurements be made of vertical profiles of 

aunospherically significant trace gases. Such measurements 

are required as input to increasingly sophisticated and 

detailed atmospheric models used to predict potenti al global 

climate change. Expanding our measurements of trace gases 

to vertical profiles has therefore become one of the major 

goals of the RITS program at NOAA. In the NOAH group 

this is being implemented for N20 and halocarbons by 

collecting flask samples for later analysis and by installing 

real-time GC analysis systems in aircraft. For aircraft such 

as the NASA ER-2 and for future pilotless drones (e.g. the 

Condor) with flight times of 8 hours or more, an airborne GC 

has the advantages of higher time resolution (up to 2 minutes 

per sample), smaller bulk and weight on a per-sample basis, 

no flask artifacts from wall losses and contamination, and 

immediate availability of analytical results. The greater 

spatial and temporal resolution achieved by the high 

sampling frequency may help resolve such issues 

70 

>-

.._ 

0 

c 

0 

0 

a:: 

O'l 

c 

·-)( 

307 

360 

340 

320 

300 

40 

... 

48 

........ ... 

0 

56 

Ju I ia n 

... ... ++ ... 

0 8 

64 

Day 

... ... 

b) 

0 

(j 

... 

72 

Fig. 7.17. N20 gaseous mixing ratios in the (a) atmosphere and (b) 

surface water for the entire cruise. Data are fitted with a locally 

weighted statistical smoothing (LOWESS) function [Cleveland, 1988). 

as whether the polar vortex is a static or dynamic processor 

for ozone depletion [Albritton et al., 1991). 

Some of the capabilities of an airborne GC were 

demonstrated during flights sponsored by the California 

State Board of Air Quality over the San Joaquin Valley and 

San Jose-San Francisco metropolitan area during August 

1990. The aim of the study was to examine the influence of 

human activities and the role of the ocean in transport of 

pollution into and out of the San Joaquin Valley. Northern 

California is one of the top ten areas of the world for the 

release of CFC-113 , a solvent used in the production of 

semiconductor circuits and metal degreasing. 

A commercial GC was modified for aircraft operation 

(Figure 7.18) to measure CFC-11 and CFC-113 once every 3 

minutes. The system pressure was regulated to be unaffected 

by changes in cabin and ambient pressure. The most 

prominent feature on all flights was the high concentration of 

CFC-113 over San Jose ("Silicon Valley"), a major producer 

of semiconductor circuit boards and chips (Figure 7 .19). 

There was also a distinct change in CFC- 11 3 concentrations 

on crossing the coastline, with values over the ocean lower 

by about 5-10%. 
l>cKAUIT I 

I 

-

... I AMOUJT'l~(Ul>Mllt(......._.TOll 

l C:c.t.llfll ll:llll&.u 

J W : ..... F\.O#COtnl(U.IA 

I ~~:.~~=-:• I It: ttiati NflfTY MCllA.AfOlll 

I sv::...n°'""YM.\C: 

I T: UlCMOUCVUJllM\4Tlt.., 

Cl 

......... 

Figure 7.18. Schematic diagram of airborne gas chromatograph. 

7.3. REFERENCES 

Albrillon, D.L., F.C. Fehsenfeld, and A.F. Tuck, Instrumental 

requirements for global atmospheric chemistry, Science, 250, 

75-81, 1990. 

Butler. J.H.. J.W. Elkins. C.M. Brunson, K.B. Egan, T.M. 

Thompson , T.J. Conway, and B.D. Hall, Trace gases in and over 

the west Pacific and east Indian Oceans during the El Niiio 

Oscillation event of 1987, NOAA Data Report ERL ARL-16, 104 

pp., NOAA Environmental Resources Laboratories, Boulder, CO, 

1988. 

Butler, J.H., J.W. Elkins, T.M. Thompson, and K.B. Egan, 

Dissolved and atmospheric nitrous oxide of the W. Pacifi c and E. 

Indian Oceans during the 1987 El Nino Oscillation event, J. 

Geophys. Res., 94(Dl2), 14,865-14,877 , 1989. 

F113 CONCENTRATIONS (PPT) 

Figure 7.19. Three-dimensional display of concentration levels of 

CFC-11 3 (in ppt) over northern California measured from an 

airborne GC on August 22. 

Butler, J.H., J.W. Elkins, T.M. Thompson, B.D. Hall, T.H. Swanson, 

and V. Koropalov, Oceanic consumption of CH3CC13: 

Implications for tropospheric OH, J. Geophys. Res., in press, 

1991. 

GCRP (Global Change Research Program), Our Changing Planet: 

The FY 1990 Research Plan , The U.S. Global Change Research 

Program, A Report by the Commillee on Earth Sciences, pp. 

118, U.S. Geological Survey, Reston, VA, 1989. 

71 

Gerkins, R.R., and J.A. Franklin, The rate of degradation of 

1,1, l -trichloroethane in water by hydrolysis and 

dehydrochlorination, Chemosphere, 19(12), 1929-1937, 1989. 

Halon Research Institute, 1989 Annual Report, Halon Research 

Institute, Washington, DC, 1989. 

Jeffers, P.M., L.M. Ward, L.M. Woytowitch, and N.L. Wolfe., 

Homogenous hydrolysis rate constants for selected chlorinated 

methanes, ethanes, e thcnes, and propanes, Environ. Sci. Technol. 

23(8), 965-969, 1989. 
8. Director's Office 

M.C. SERREZE, J.D. KAHL (University of Wisconsin-Milwaukee), and R.C. SCHNELL 

8.1. LOW-LEVEL TEMPERATURE INVERSIONS 

OF THE EURASIAN ARCTIC AND COMPARISONS 

WITH SOVIET DRIFTING STATION DATA 

8 .1.1. INTRODUCTION 

Results from a number of recent studies point toward the 

need for more detailed investigations of spatial and temporal 

variability in the Arctic temperature inversion. For example, 

the height of the inversion base can be used to estimate the 

geostrophic drag coefficient [Overland, 1985; Overland and 

Guest, 1991; Overland and Davidson, 1991] which, in tum, 

is needed as input into sea ice and coupled ice-ocean models 

[e.g., Hibler and Bryan, 1987] to simulate sea-ice motion. 

With regard to Arctic energy budgets, the strength of the 

inversion influences the magnitude of heat and moisture 

fluxes through leads and polynyas, and the depth of vertical 

mixing [Andreas, 1980; Andreas and Murphy, 1986]. 

Schnell et al. [1989a] recently reported that plumes of heat 

and condensate rising from large leads may sometimes 

penetrate the inversion layer to a depth of up to 4 km, 

suggesting that heat and moisture can be mixed through a far 

greater depth of the Arctic troposphere than previously 

thought. 

Turning to other lines of research, elevated concentrations of pollution gases and aerosols from AGASP results 

have been observed to coincide with the top of the inversion 

layer [Bridgman el al., 1989]. Photochemical destruction of 

boundary-layer ozone at Arctic sunrise recently documented 

by Barrie et al. (1 988] and Oltmans et al. (1989], appears lo 

involve a meteorological modulation process in which 

ozone-depleted air within the inversion layer is occasionally 

replaced by above-inversion, ozone-rich air, via a poorly 

understood mixing process. 

Here we examine characteristics of the inversion layer 

using up to 12 years of twice-daily sounding data from 31 

coastal and inland stations from the Eurasian Arctic and 

approximately 6 station-years of data from three Soviet 

drifting stations within the interior pack ice near the North 

Pole. The sounding data base we use is at least an order of 

magnitude larger than available for previous studies. 

The sounding data were obtained from a NOANCIRES 

Arctic radiosonde data set being developed for the NOAA 

Climate Change Program. These data tapes contain 1.8 

million Arctic soundings of up to four times daily for 

regularly-reporting Eurasian stations north of 60'N for the 

period 1976-1987, as well as aircraft, ship, and drifting 

ice-station data. Station locations are plotted in Figure 8.1. 

Pressure, geopotential height, temperature, dewpoint 

depression, wind direction and speed, and accompanying 

quality flags arc given for each sounding. For this study, we 

use soundings for both 0000 and 1200 UTC. 

Fig. 8.1. Location of the 31 Arctic land stations and drifting station 

data used in this study, with drifting station positions shown at the 

beginning of every month that data are available. 

In the present study, we are only concerned with low-level 

inversions defined here as those with a base below the 700 

mb level. Inversions are identified using the detection 

algorithm developed by Kahl (1990]. Each temperature 

profile is scanned upwards from the surface to the 700 mb 

level to locate the first layer (if any) in which temperature 

increases with altitude, with the bottom of this layer defining 

the inversion base. The inversion top is defined as the 

bottom of the first subsequent layer in which the temperature 

decreases with altitude. Since Arctic temperature profiles 

often exhibit a complicated vertical structure [Belmont, 

1957], thin negative-lapse layers are occasionally encountered in the upward scan. If these layers are thin (<100 m) 

and the next layer above shows an increase in temperature 

with altitude, the thin layer is considered to be embedded 

within the overall inversion layer. Examples of the 

technique are given by Kahl (1990]. 

8.1.2. RESULTS: SEA ICE/LAND COMPARISONS 

Monthly inversion frequencies for the drifting stations are 

plotted in Figure 8.2, along with the estimated total cloud 

cover for the central Arctic, based on published data from 

Huschke (1969]. The cloud-cover data will be discussed in 

the next section. Other monthly statistics are shown in 

Figure 8.3. The top of each bar in Figure 8.3 is the median 

inversion top, and the bottom of each bar is the median 

height of the inversion base. The total length of each bar is 

hence approximately the median inversion depth. Also 

plotted on a separate scale is the median temperature 

difference across the inversion layer. For comparison, we 

plot results for station Zhigansk, located on the Siberian 

tundra (66.8'N, 123.4'E) (Figures 8.4 and 8.5). This station 

is reasonably typical of all the inland sites (Figure 8.1). 

72 
DRIFTING STATl,ONS 

100 

'O' 

~ 80 

d 

w 

a:: 60 100. LL 'O' 

z ,!::, 

0 a:: 

a: 

(/) 40 80 ~ 

w 0 

> O ALL INVERSIONS ("t.j () 

z ELEV. INVERSIONS(-/.) 20 60 g CLO\JD COVER (v.) 0 

_J 

() 

0 40 

J F M A M J J A s 0 N D 

MONTH 

Fig. 8.2. Monthly inversion frequencies from drifting station data 

and sky-cover percentage for the central Arctic [cloud cover data 

from Huschke, 1969). 

1600 

1400 

~1200 w 

() 

Li: 000 (f) 

w 

~ 800 m 

<( 

1-

13 600 

w 

I 

400 

200 

DRIFTING STATIONS 

J F M A M J J A S 0 N D 

MONTH 

16 

14 

12 

p 10'-' 

~ 

z 

8 2 

(/) 

a:: 

w 

> 

6 ~ 

4 

2 

Fig. 8.3. Monthly median inversion top (top of bars), base (bottom 

of bars), and temperature difference (solid line) from drifting station 

data. 

100 

'O' ,!::, 80 

d 

w 

a:: 

LL 60 

z 

0 

(/) 4 0 

ex: 

w 

> 

z 

20 

ZHIGANSK (66.8°N,123.4°E) 

0 ALL INVERSIONS (">'I 

e ELEV. INVERSIONS (VJ 

J F M A M J J A S 0 N D 

MONTH 

Fig. 8.4. Monthly inversion frequencies from station Zhigansk. 

1600 

1400 

200 w 

() 

Li: 

~1000 (f) 

w 

e:; 800 

m 

<( 

1-G 600 

w 

I 

400 

200 

ZH IGANSK (66.8°N,123.4°E) 

J F M A M J J A S 0 N D 

MONTH 

16 

14 

12 

p 10'-' 

~ 

z 8 2 (/) 

a: 

w 

> 

6 ~ 

4 

2 

Fig. 8.5. Monthly median inversion top (lop of bars), base (bottom 

of bars), and temperature difference (solid line) for station 

Zhigansk. 

73 
An initial comparison shows a strong seasonal cycle in 

inversion characteristics over both the pack ice and land. 

However, while the seasonal range in inversion frequencies 

over the pack ice is only 17%, it is over three times as large 

(53%) for Zhigansk, consistent with the stronger solar flux at 

the latter, more southerly station. Also, subsequent to spring 

snow melt, incident radiation at Zhigansk can be used to heat 

the atmosphere rather than to melt ice. In general, the 

magnitude of elevated inversions is similar at both locations. 

Differences between the two sites are more apparent when 

Figures 8.3 and 8.5 are examined. During the winter months 

the temperature difference across the inversion layer is 

considerably higher at Zhigansk; in January it reaches 17' 

for Zhigansk, but only 12' for the drifting stations. While 

differences in cloud cover may in part be responsible for 

these and other differences, the contrast in 6 T during winter 

is consistent with the moderating influence of the heat flux 

through the sea-ice cover as compared to the strong radiative 

losses from the snow-covered land surface. Note that the 

effects of leads and thin ice will be absent in summer due to 

melting conditions. 

Both the drifting stations and Zhigansk show a sharp drop 

in inversion 6T during spring, but it is much more pronounced at Zhigansk, also consistent with removal of the 

snow cover and the stronger downwelling solar radiation at 

the latter location. From May through September, the 

temperature difference across the inversion layer is Jess than 

2'C at Zhigansk, but from 2-4°C over the pack ice. Both 

sites show a mixed layer below the inversion from May to 

September. While it never rises above 400 m at the drifting 

stations, it rises to over 650 m at Zhigansk in June when 

potential solar radiation receipts at the surface would be 

maximized and strong turbulent heat transfer to the atmosphere would occur. The absence of this June peak at the 

drifting stations demonstrates the tendency for absorbed 

radiation over the sea ice to be used in melt. During autumn, 

surface-based inversions are again the rule at both sites with 

inversion 6T also rapidly rising. By November, however, 

the values at Zhigansk exceed those for the pack ice, again 

suggestive of the moderating effect of the winter heat flux 

through the ice cover and stronger heat Joss from land. 

In Figure 8.2 cloud cover over the central Arctic exhibits 

a pronounced seasonal cycle. During winter, limited cloud 

cover can be largely understood in terms of infrequent 

cyclonic activity [Serreze and Barry, 1988) and the low 

moisture content of the cold, winter atmosphere. During 

summer, cloud cover is typically extensive (80-90%). While 

part of the summer increase is comprised of middle- and 

high-level clouds associated with increased cyclonic activity 

[Serreze and Barry, 1988), the most notable change is the 

development of extensive low-level Arctic stratus. According to /lerman and Goody (1976), Arctic stratus forms when 

moist air .masses move over the ice and condense. Once 

formed, it persists due to the presence of a wet, convectionlimiting sea-ice surface and weak dissipative mechanisms. 

Since large-scale advection will be strongly associated with 

synoptic-scale weather systems, increased cyclonic activity 

in summer and the development of Arctic stratus go 

hand-in-hand. 

Cloud cover-inversion relationships over sea ice are 

particularly complex during summer. When the ice surface 

is melting, it will be at a fixed temperature. Although the 

summertime surface net radiation budget is positive, the 

melting surface, in conjunction with advection of relatively 

warm air from more southerly latitudes, will tend to maintain 

an inversion. Persistent Arctic stratus is favored by limited 

mixing which implies that during summer, variations in the 

inversion layer will, to some extent, drive the cloud cover 

variations. 

8.1.3. SUMMARY AND CONCLUSIONS 

We believe that our study has opened several avenues for 

further research. For example, it may be possible to relate 

spatial variability in inversion features to the distinct 

horizontal patchiness observed in Arctic haze layers [e.g., 

Bridgman et al., 1989). Closer studies at shorter time scales 

of the spatial distribution of inversion frequencies and 

characteristics in winter and spring, and their relationship 

with synoptic activity, may be useful in identifying those 

locations and climatic conditions in which the inversion 

layer temporarily breaks down. These regions could be 

useful in identifying locations where boundary-layer ozone 

destruction [Barrie et al., 1988; Oltmans et al., 1989] may 

be most pronounced and most easily measured. Further 

analysis of the inversion structure over the Arctic Ocean 

with additional drifting station data and dropsonde data is 

already underway. Results may provide some guidance for 

the estimation of parameters needed by sea-ice modelers, and 

help in investigating temporal and regional variations in the 

potential for plumes of condensate from leads and polynyas 

to penetrate the inversion layer [Schnell et al., 1989a). 

Finally, possible climatic change in the Arctic as forecast 

by models [e.g., Hansen et al., 1988) would be expected to 

impact cloud cover and the inversion layer. In studying the 

boundary-layer properties of the South Pole, Stone and Kahl 

[ 1991] suggest that the inversion depth, temperature 

difference across the inversion layer, and the bulk 

boundary-layer wind shear may be useful indices for 

monitoring climatic change since they respond to both 

radiative and dynamical forcings. Studies of these 

parameters may yield useful information in the Arctic. 

74 

8.2. BOUNDARY LA YER O ZONE FLUCTUATIONS 

RELATED TO 0RGANOBROMINE 

PHOTOCHEMISTRY IN THE SPRINGTIME ARCTIC 

P.J. SHERIDAN, R.C. SCHNELL AND J.M. HARRIS 

8.2. 1. INTRODUCTION 

Recent springtime atmospheric field experiments in the 

Arctic have shown episodic ground-level 0 3 depletions 

accompanied by high levels of bromine-containing com-
pounds collected on particulate filters (FBr) [Barrie et al., 

1988; Oltmans et al., 1989; Sturges et al., 1991). In order to 

fort.her investigate the phenomenon of ground-level Arctic 

0 3 destruction, an airborne field experiment was performed in 

the eastern Arctic in t.he spring of 1989. During March 4-

April 1, 1989, t.he NOAA WP-3D Orion was deployed to 

Bodo, Norway, in support of the CEAREX/AGASP-ffi 

m1ss10n. The aircraft was extensively outfitted for t.he 

measurement of atmospheric and meteorological parameters 

and for the sampling of atmospheric gases and aerosols, 

similar to its configuration on t.he 1986 AGASP-Il experiment [Schnell et al., 1989b). The regions selected for study 

were t.he Norwegian and Greenland Seas and the ice-covered 

Arctic Ocean north of Spitsbergen. Aerosol sampling during 

these flights was concentrated in the surface inversion layer 

above the pack ice, specifically to address the 0 3 depletion 

events. 

The major objectives of this study were to (1) make 

extended measurements out over the ice in the surface 

inversion layer where only small fractions of a limited 

number of aircraft-collected aerosol samples were taken in 

past studies, (2) determine if 0 3 destruction was occurring 

immediately above and downwind of large leads, which 

would support the hypothesis of a rapid 0 3 loss mechanism, 

(3) extend t.he geographic range of t.he 0 3 depletion 

observations into the Norwegian Arctic and determine 

whether a similar FBr/03 relationship is present there, and 

(4) determine the chemical species responsible for photolytic 

ground-level 0 3 destruction in the springtime Arctic. Here 

we present bulk aerosol and trace gas chemistry data, along 

with meteorological information which assisted us in our 

interpretations of the chemistry data. 

8.2.2. EXPERLVIENTAL 

Since the aircraft was shared among several groups with 

different flight requirements, only certain flights during the 

AGASP-III experiment were designated atmospheric 

chemistry fli ghts. It was on these flights that we concentrated our sampling efforts in the surface inversion layer and 

free troposphere over the pack ice. Samples or measurements collected during these intensive periods included bulk 

aerosols and inorganic/acidic gases in three-stage filter 

packs, size-segregated aerosols on thin-film cascade 

impactor substrates, trace organic gases in grab flasks, and 

ozone concentrations in real time with several onboard ozone 

monitors. Specific details concerning the sample collection 

and analytical procedures used in this study, and the steps 

taken to minimize potential aircraft sampling artifacts, have 

been presented elsewhere [Sheridan and Zoller, 1989; 

Sheridan et al., 1991]. Thus only a brief description of our 

experimental methods follows. 

Sample Collection 

A high-volume, aerosol filter sampling system was used 

to collect atmospheric particles and gases in 11-cm diameter 

filter packs during t.he AGASP-III flights. Mass flow rates 

through the system with the three filters in line were 350-500 

standard liters per minute at the low sampling altitudes, with 

volume flow rates reasonably close to the mass flows 

(usually within -10% ). Standard conditions for our mass 

flowmeters were defined as 760 mm Hg and 25°C, and all 

concentration values were calculated using volumes 

corrected to standard conditions. 

The aerosol sampling system collected atmospheric 

particles on Teflon filters in the first stage of the filter pack. 

The collection efficiency of the type FA Teflon filter is 

stated by the manufacturer to be >99.9% for 0.3 μ m 

particles. Species which passed the particulate filter were 

forced through the two KOH-treated Whatman filters, which 

efficiently collect acidic gases. Although there is some 

uncertainty concerning the identity and collection efficiency 

of Br-containing species on base-impregnated filters, a 

recent survey of the literature showed general agreement that 

HBr, atomic Br, BrON02, and, to a lesser extent, Br2, would 

be efficiently trapped [Sturges et al., 1991). Organic vapors 

are generally not retained on base-treated filters. Less 

certain arc the collection efficiencies of other species, 

including BrO, BrNO, HOBr, and H2

0Br. The potential 

sampling artifacts of gas trapping by the particulate filter and 

volatilization of Br-containing species on the particulate 

filter with subsequent trapping on the base-treated filters 

have been discussed elsewhere [Sturges et al., 1991). 

Ambient air samples were collected in electropolished 

stainless steel 1-L flasks for subsequent GC analysis. The 

time required for purging and collection of a pressurized 

(3-atrn absolute) gas sample was 1-2 minutes, depending on 

altitude. Details concerning sample preparation strategies 

and contamination precautions have been published 

elsewhere [Rasmussen et al., 1983). Ozone was measured 

with a Dasibi continuous 0 3 monitor. 

Analytical Procedures 

75 

INAA was used to determine the concentrations of 10-20 

trace elements present on one-half of each aerosol filter 

sample. A few elements for which INAA is not sensitive or 

which showed large interferences were determined by 

analysis of the acid extracts of another quarter of each 

aerosol filter using inductively-coupled plasma atomic 

emission spectroscopy (ICP-AES). Concentrations of 

IN AA-determined elements were also corroborated using this 

method. Major ion analysis of the filters was conducted 

using ion chromatography. The final one-quarter of each 

aerosol filter was used for these analyses, while half-filter 

sections of the second- and third-stage filters were used. The 

water soluble fraction of the aerosol was extracted with 

triple-distilled water in an ultrasonic bath. Ions determined 

using this technique included Cl-, Br- , NO~ . SO~ , Na .. NH:, 

and K+. 

Trace gas analysis was performed using a temperatureprogrammed Perkin-Elmer Model 3920B GC with an 

electron capture detector. Details concerning the GC 

column, thermal desorption steps, and other analytical 

procedures are reported in Rasmussen and Khalil [1984]. 

The analytical precision for the measured Br-containing trace 

gases is better than 2%. 
Isobaric backward air mass trajectories were calculated 

for the purpose of estimating air parcel motion to the 

sampling locations. The computer model that produced these 

trajectories was developed by Harris (1982). The primary 

input for the trajectory program consists of gridded wind 

components at mandatory pressure levels, produced by the 

NMCs global atmospheric model. The resolution of these 

data grids is 2.5' of latitude and longitude and 12 hours, with 

grids produced at 0000 GMT and 1200 GMT each day. 

Isentropic trajectories were not calculated because the model 

does not produce reliable trajectories near the surface in the 

mixed boundary layer. 

8.2.3. RESULTS 

Figure 8.6 shows the approximate collection location for 

each of the eight AGASP-ill tropospheric filter samples (A 

through H) and the extent of near-solid (>9/10) pack ice as 

of March 20 and 28, 1989 (data supplied by Norwegian 

Meteorological Institute). The 90% solid ice contour was 

within - 100 km of the ice edge everywhere in the figure 

except in the area southwest of Spitsbergen, where large 

regions of drifting ice (10-90% ice cover) were observed. 

AGASP-lli chemistry missions were characterized by a 

high-altitude ferry segment to the research area, a slow 

ramping descent to map the atmospheric structure at -500 

feet min- 1 over a predetermined spot on the ice, several long 

duration, low-altitude sampling/measurement runs, and a 

rapid climb and ferry back to Bodo. Figure 8.7 shows the 

WP-3D descent profile for ambient temperature, 0 3 

concentration, and aerosol light scattering at 83 'N, lO'E 

during flight 311. This profile featured a strong (-15'C) 

temperature inversion, the base of which was at 500-600 m 

above the ice. An isothermal layer was encountered during 

the descent at -40 m radar altitude. This was the SSL over 

the ice on March 30 described in Walter and Overland 

(1991). Aerosol light scattering measurements with a 3-1.. 

nephelometer [Bodhaine et al., 1991] indicated no major 

aerosol layers below the top of the inversion. The 0 3 trace 

appears to show significant 0 3 depletion occurring well 

below the top of the SSL. Allowing for the 15 second time 

response of the Dasibi 0 3 monitor, however, the altitude at 

which 0 3 concentrations dropped to zero was within a few 

meters of the top of the SSL. 

Data on the concentrations of various aerosol and gas 

species determined from tropospheric continuous 0 3 

measurements, filter samples, and concurrently collected gas 

flasks are presented in Table 8.1. Additionally, the percentage of the sampling period for each filter that was spent in 

ozone-depicted (<20 ppbv 0 3) air is listed. Excess filterable 

Br (XSFBr) is defined as the amount of Br captured on the 

filter in excess of the amount expected from a marine salt 

contribution, and was computed from the total elemental Br 

and Na concentrations determined by INAA. The Br/Na 

mass ratio used in these calculations was 0.0043, which is 

appropriate (correcting for Br volatilization) for aged 

aerosols as discussed by Sturges and Barrie [1988). We 

20'E 

- 90io eolid ice extent • 20 M&rcb 1989 

--- 909. solid ice eucnt · 28 Mach 1989 

Fig. 8.6. Map of the European Arclic showing the extent of solid 

ice during lale March 1989 and approximate collection locations of 

the eight AGASP-ill high volume filter samples. 

P-3 PROFILE 83N. lOE - 3/30/89 

10000 

~ l 00 

< 

Cl 

< 

~ 

10 

: ,' : , ,, 

,r 

,,,"' ; , 

I 

< 

. 

, ' 

, 

- TEMP 

03 

a •p 

-45 -35 -25 - 15 -5 

TEMPERATURE (C) 

0 20 40 60 80 

OZONE {ppbv) 

0 5 1 0 15 20 

Fig. 8. 7. Descent profile of ambient temperature, 0 3 and aerosol 

light scattering for March 30, 1989, showing the atmospheric 

struc1ure on flight 311. Sample collection period H was conducted 

under these conditions. Notice the 40-50 m deep isothermal or 

slightly stable layer below the strong inversion. 

76 
TABLE 8.1. Concentrations of Various Gas and Aerosol Species on Filters A-H During AGASP-III Sampling 

Concentrations 

Species A B c D E F G H 

Aerosol 

Na (ng m'3) 51 B 31 112 59 463 11 80 34 

Cl (ng m·3) 44 B B 132 55 313 1230 101 

Br (ng m·3) 4.1 2.6 1.0 5.7 6.3 35.7 6.9 11.5 

XSFBr (ng m·3) 3.9 2.5 0.8 5.2 6.0 33.7 1.9 11.3 

l\'H: (ng m'3) 400 960 620 240 280 280 180 190 

so!· (ng m'3) 1490 700 1670 790 1150 940 1300 690 

NOj (ng m·3) 27 B• B 9.1 14 <18t 92 11 

Gas Phase 

03 avg(ppbv)t 37 47 46 

%T<20 (ppbv)§ 1 0 0 

CH3Br (pptv) 23 9.6 12 

CH2Br2 (pptv) 2.1 3.6 5.3 

CH2BrCH2Br (pptv) 26 3.5 2.2 

Cl-1Br3 (pptv) 2.1 1.9 4.7 

*Value was at or below filter blank 

tValue listed was instrumental detection limit 

tMean 0 3 concentration during filter sampling period 

§Percentage of sampling t[me spent in ozone-depleted air (03 < 20 ppbv) 

;tData not available - flasks not collected during this period 

were unable to accurately assess the motor vehicle contribution to atmospheric Br in these samples, because Pb was not 

detected above our instrumental ICP-AES detection limit 

(DL) of - 0.05 ppm. However, based on levels of other 

INAA- and IC-determined species, a strong anthropogenic/ 

urban component to these samples is not expected. Total 

so; concentrations measured on these flights (most of which 

were conducted specifically to find and sample Arctic haze) 

ranged between 700 and 1700 ng m·3, which is substantially 

lower than past springtime Arctic haze so; and non-sea salt 

(XS) SO; measurements (2-3 μg-3) reported by other 

investigators [Barrie and Hoff, 1985; Iverson and Joranger, 

1985]. Most of the filters showed XS so; fractions of 

>0.95. The NH;JXs SO; mole ratio for most of the samples 

(excluding the marine aerosol sample G) was high and 

ranged between 1.32 and 1.99. These values suggest an 

aged, background aerosol present at this time in the 

European Arctic, rather than a new pulse of pollution. This 

is consistent with visual observations of very light haze 

episodes during AG ASP-III. 

Figure 8.8 shows· XSFBr concentrations from the eight 

tropospheric filter samples plotted against mean 0 3 concentration during each sample collection period. The strong 

anticorrelation between these two parameters first observed 

at Alert [Barrie el al. , 1988] is again obvious. The reasons 

for this relationship out over the ice are probably the same as 

at Alert. A strong temperature inversion over the pack ice 

presents a barrier to 0 3 mixing down to the surface from 

higher altitudes. The 0 3 below the top of the inversion is 

probably destroyed through photochemical reactions 

involving Br radicals. A shallow surface-based SSL which 

35 33 2.4 38 13 

4 12 96 0 60 

NA;i< 10 11 14 NA 

NA 4.3 5.3 4.2 NA 

NA 1.7 3.3 1.8 NA 

NA 13 5.1 13 NA 

was not observed at Alert limited the extent of severe ozone 

depletion to -40-50 m above the pack ice surface. The PBL 

above this SSL showed less 0 3 depletion, as would be 

expected with a surface source of reactant and a larger 

reservoir volume. Instead of shifting winds causing low-03, 

high XSFBr (onshore) and high-03, low XSFBr (offshore) 

air to flow over a stationary sampler as at Alert, the sampler 

in this study was mobile and collected samples and measurements in the different air masses. 

A 

AGASP 306-311 TROPOSPHERIC SAMPLES 

B C D E F 

SAMPLE 

G H 

Fig. 8.8. Plot of XSFBr and mean 0 3 concentration for the eight 

sampling periods. Samples F and H were the only ones showing 

severe 0 3 depletion from typical tropospheric values. A linear 

regression least-squares fit of these data produced a correlation 

coefficient of r = -0.90. 

77 
While mean 0 3 concentrations varied inversely with 

XSFBr, other 0 3-related measurements also showed strong 

anticorrelations during this period. A linear regression fit of 

XSFBr plotted against the percentage of sampling time spent 

in 0 3-depleted air (<20 ppbv 0 3) yields a correlation value of 

r = -0.94. Similarly, a fit of the minimum 0 3 concentration 

measured during sampling plotted against XSFBr gives a 

high negative correlation (>-0.8). 

Observational and experimental evidence suggest a fast 

reaction mechanism at work in the photolytic destruction of 

surface 0 3 over the pack ice. Sturges et al. (1 991] have 

suggested a reaction rate of less than one day for the 

reduction of 0 3 from typical well-mixed tropospheric 

concentrations (35-40 ppbv) to depleted values (<25 ppbv), 

based on the transport time from ice covered regions with 

exposed seawater (i.e., leads) to Barrow, Alaska. The same 

authors have shown in laboratory photochemical experiments 

that within minutes of irradiation with actinic radiation, 

Arctic air samples containing organobromine gases and 0 3 

produced significant amounts of filterable (i.e., aerosol) Br. 

Since we were sampling continuously in and around 

lead-filled regions, mixing and dilution of the air mass 

during transport to a remote sampler did not occur. Our 

AGASP-Ill air samples collected over solid ice (with some 

leads) and below the top of the SSL (samples F and H) 

showed almost complete 0 3 destruction over large fractions 

of the sampling period. We believe that the concentrations 

of Br-containing species and 0 3 in these samples are more 

representative of the photochemistry occurring over the pack 

ice than those collected a day downwind on the Arctic coast. 

Two samples collected close spatially and temporally in 

the near-isothermal SSL were compared for evidence of 

catalytic 0 3 destruction by gaseous Br compounds [Sheridan 

et al., 1991]. Table 8.2 shows the concentrations of 0 3, 

CHBr3, and XSFBr for the two samples, and the respective 

concentration changes of these species over the 2-day period. 

The first sample showed no significant 0 3 depletion and 

concentrations of CHBr3 and the other Br-containing gases 

were similar to those reported by other researchers for 

springtime European Arctic conditions [Berg et al., 1984; 

Rasmussen and Khalil, 1984]. The 0 3 decrease ~03 = -30.6 

ppbv) during the period between samples E and F was more 

than three orders of magnitude higher than the CHBr3 

reduction, suggesting a reasonably efficient catalytic cycle 

for 0 3 destruction. CHBr

3 decreased in concentration by 7 .9 

pptv, which, assuming only one Br atom is released during 

TAB LE 8 .2. Concentrations and Flucuations of 0 3 and Br 

Species Collected North of Spitsbergen During Flights 

AGASP 309 and 310 (Samples E and F) 

Sample E Sample F 6. 

Species Concentration Concentration Concentration 

0 3 (ppbv) 33 2.4 -30.6 

CHBr3 (pptv) 13 5.1 -7.9 

XSFBr (ng m·3) 6.0 33.7 +27.7 

photolysis, converts to a loss of 28.2 ng Br m·3 at STP. The 

observed increase in XSFBr during this period was nearly 

identical at 27 .7 ng m·3. 

8.2.4. DISCUSSION AND SUMMARY 

As is evident in Figure 8.8 the major 0 3 destruction and 

XSFBr episodes were observed in the SSL during collection 

of filter samples F and H. It is important to identify what 

conditions were different in these two samples that may have 

contributed to the aerosol chemistry. These two samples 

were collected in a -50 m deep SSL above solid pack ice 

with large leads present. Two other samples (D and E) were 

also collected in a SSL and showed no such 0 3 depletion/ 

aerosol Br enrichment. Samples F and H were collected far 

to the north of Spitsbergen, but so was sample E which, as 

discussed above, was chemically quite different from the 

0 3-depleted samples. Wind direction may provide the 

answer in this case. Isobaric backward air mass trajectories 

at appropriate pressure levels arriving at the midpoint 

location of each filter sample were calculated. The largest 

0 3 depletions and XSFBr concentrations were observed 

during sampling north of Spitsbergen in light winds with a 

northerly component (filter samples F and H) [Sheridan et 

al., 1991]. Winds for sample E were from the North 

Atlantic, arriving at the aircraft location from the south and 

southeast during the sample collection period. 

Thus a few generalizations can be made concerning the 

geographic and meteorological conditions present during 

episodes of 0 3 depletion in the Norwegian Arctic boundary 

l ayer. Samples F and H were the only ones showing any 

significant 0 3 depletion, and were characterized by the 

following conditions: 1) sample collection over pack ice with 

relatively Jillie open water (as opposed to collection near the 

ice edge); 2) a strong (> 10°C) low level temperature 

inversion was present to limit mixing with free troposphere 

air; 3) a -50 m thick slightly stable layer was present that 

acted as an additional barrier to mixing and which capped 

the significant 0 3 destruction; 4) light winds of 5-10 m sec· 1 

or less; and 5) northerly winds transporting Arctic rather 

than marine air masses to the research area. 

The remaining six periods when tropospheric samples 

were collected on AGASP-III were missing one or more of 

the conditions characterizing sample collection periods F and 

H. When sampling occurred in the free troposphere, 

concentrations of 0 3 were relatively high and Br-containing 

species low. When sampling occurred in the PBL above the 

SSL or when the SSL was not present (i.e., the temperature 

profile increased continuously with altitude up to the 

inversion height), 0 3 concentrations did not show severe 

depletions. In these cases, a much larger reaction reservoir 

(several hundred or more meters in depth) was probably 

responsible for the modest 0 3 reductions. When marine 

aerosol was sampled, either because sample collection was 

near the broken ice edge or winds were from the direction of 

open water, 0 3 was not severely depleted and XSFBr was 

relatively low. Most of the filterable Br in these samples 

was attributed Lo a bulk seawater contribution . 

78 
Concentrations of four Br-containing gases were 

determined by gas chromatography. None showed a 

persistent relationship with either 0 3 or XSFBr concentration. This is probably because of the variable meteorological 

factors that appear to influence the effic iency of the 

photochemical reactions. Two samples collected spatially 

and temporally close in the SSL were compared for aerosol 

and gas composition. The first sample showed no significant 

0 3 depletion and concentrations of the Br-containing gases 

were similar to those reported by other researchers for 

springtime European Arctic conditions. The second sample 

was collected 2 days later near the same geographic location 

and showed a significant 0 3 depiction over this time period 

with a concurrent CHBr3 decrease and XSFBr increase. The 

Br released by the CHBr3 losing one Br atom per molecule 

was nearly equal to the Br bound in XSFBr compounds. 

While this comparison is only as valid as the initial assumptions concerning similarity of the samples and a limited 

mixing scenario (i.e., few other sources and sinks) for the 

reacting species, the fact that Br in gaseous CHBr3 and 

aerosols undergoes inverse and nearly equal changes in 

concentration over this short time period suggests that 

CHBr3 is a key species acting to rapidly destroy 0 3 over the 

pack ice. Unfortunately, the reaction rate for the gas phase 

photolysis of CHBr3 is known to be far too slow to account 

for the concentration flucuations observed in this and other 

studies. This raises the possibility that heterogeneous 

chemical reactions involving organic Br in the particulate 

phase may be important. The aerosol surface area can 

provide a means for reacting atmospheric particles to 

encounter one another with greater frequency, which is a 

suggestion from other studies [Sturges et al., 1991; Sheridan 

et al., 1991]. More study is needed on the potential role of 

aerosols accelerating boundary layer 0 3 destruction through 

heterogeneous photochemical reaction mechanisms. 

Acknowledgments. The Arctic low-level temperature 

inversion study was supported by contracts from the NOAA 

Climate and Global Change Program (NA85RAH05066), the 

National Science Foundation (DPP-8822472), the Electric 

Power Research Institute (RP2333-07), and the Office of 

Naval Research University Research Initiative (N00014-86-

K-0695). M. Rehder (CIRES) provided valuable programming assistance. We thank the Univ ersity of Washington for 

providing most of the aerosol analyses. We appreciate the 

trace gas data supplied by the Oregon Graduate Institute of 

Science and Technology. Thanks are also expressed to the 

NOAA/Aircraft Operations Center in Miami, Florida, for a 

well-conducted field experiment at a remote site. This study 

was supported through grants from NASA, ONR, and NSF. 

8.3. REFERENCES 

Andreas, E.L., Estimation of heat and mass fluxes over Arctic lead s. 

Mon. Wea . Rev., 108, 2057-2063, 1980. 

Andreas, E.L. and B. Murphy, Bulk transfer coefficients for heat 

and momentum over leads and polynyas, J. Phys. Oceanogr., 16, 

1875-1883, 1986. 

Barrie, L.A. and R.M. Hoff, Five years of air chemistry observations in the Canadian Arctic, Atmos. Environ. 19, 1995-2010, 

1985. 

Barrie, L.A., J.W. Bottenheim, R.C. Schnell, P.J. Crutzen and R.A. 

Rasmussen, Ozone destruction and photochemical reactions at 

polar sunrise in the lower Arctic atmosphere, Nature, 334, 

138-141 , 1988. 

Belmont, A.O., Lower tropospheric inversions at ice island T-3 , J. 

Atmos. Terres. Phys .. Special Supplement, 215-284, 1957. 

Berg, W.W., L.E. Heidt, W. Pollock, P.O. Sperry, and R.J. 

Cicerone, Brominated organic species in the Arctic atmosphere, 

Geophys. Res. Lett., 11 , 429-432, 1984. 

Bodhaine, B.A., N.C. Ahlquist, and R.C. Schnell, Three wavelength 

nephelometer suitable for aircraft measurement of background 

aerosol scattering coefficient, Atmos. Environ. 25A, 2267-2276, 

1991. 

Bridgman, H.A., R.C. Schnell, J.D. Kahl, G.A. Herbert and E. 

Joranger, A major haze event near Point Barrow, Alaska: 

analysis of probable source regions and transport pathways, 

Atmos. Environ ., 23, 2537-2549, 1989. 

Hansen, J., I. Fung, A. Lacis, D. Rind, S. Lebedeff, R. Rudey, G. 

Russell and P. Stone, Global climate changes as forecast by the 

Goddard Institute for Space Sciences three-dimensional model, J . 

Geophys. Res., 93, 9341-9364, 1988. 

Harris, J.M., The GMCC atmospheric trajectory program, NOAA 

Tech. Memo. ERL-ARL-116, 30 pp., NOAA Environmental 

Research Laboratories, Boulder, CO, 1982. 

Herman, G. and R. Goody, Formation and persistence of Arctic 

stratus clouds, J. Atmos. Sci., 33(8), 1537-1553, 1976. 

Hibler, W.D., III, and K. Bryan, A diagnostic ice-ocean model, J . 

Phys. Oceanogr., 17, 987-1015, 1987. 

Huschke, R.E., Arctic cloud statistics from "air-calibrated surface 

weather observations," Memorandum RM-L173-PR, 79 pp., Rand 

Corporation, Santa Monica, CA, 1969. 

Iverson, T., and E. Joranger, Arctic air pollution and large scale 

atmospheric flows, Atmos. Environ . 19, 2099-2108, 1985. 

Kahl, J.D., Characteristics of the low-level temperature inversion 

along the Alaskan Arctic coast. Int. J. Climat ., JO, 537-548, 1990. 

Oltmans, SJ ., R.C. Schnell, P.J. Sheridan, R.E. Peterson, S.M. Li, 

J.W. Winchester, P.P. Tans, W.T. Sturges, J.D. Kahl, and L.A. 

Barrie, Seasonal surface ozone and filterable bromine relation· 

ship in the high Arctic. Atmos. Environ., 23, 243 1-2441, 1989. 

Overland, J.E., Atmospheric boundary layer structure and drag 

coefficients over sea ice. J. Geophys. Res., 90, 9029-9049, 1985. 

Overland, J.E., and K.L. Davidson, Geostrophic drag coefficients 

over sea ice, Tel/us, in press, 1991. 

Overland, J.E., and P.S. Guest, Control of minimum snow and air 

temperatures over Arctic sea ice during winier, J . Geophys. Res., 

96(C-3), 4651-4662, 1991. 

Rasmussen, R.A., M.A.K. Khalil and R.J. Fox, Altitudinal and 

temporal variation of hydrocarbons and other gaseous tracers of 

Arctic haze, Geophys. Res. Lett. 10, 144-147, 1983. 

Rasmussen, R.A., and M.A.K. Khalil, Gaseous bromine in the 

Arctic and Arctic haze, Geophys. Res. Lett. 11, 433 -436, 1984. 

Schnell, R.C., R.G. Barry, M.W. Miles, E.L. Andreas, L.F. Radke, 

C.A. Brock, P.J. McCormick, and J.L. Moore, Lidar studies of 

leads in Arctic sea ice, Nature, 339(6225), 530-532, l 989a. 

Schnell, R.C., T.B. Watson, and B.A. Bodhaine, NOAA WP-30 

instrumentation and flight operations on AGASP-II, J. Atmos. 

Chem. 9, 3-16, 1989b. 

Serreze, M.C., and R.G. Barry, Synoptic activity in the Arctic 

Basin ,]. Climate, 1(12), 1276- 1295, 1988. 

Sheridan, P.J., and W.H. Zoller, Elemental composition of 

particulate material sampled from the Arctic haze aerosol, J. 

Atmos. Chem. 9, 363-381, 1989. 

Sheridan, P.J., R.C. Schnell, W.H. Zoller, N.D. Carlson, R.A. 

79 

Rasmussen, J.M. Harris, and H. Sievering, Composition of 

Br-containing aerosols and gases related to boundary layer ozone 

destruction in the Arctic, Atmos. Environ., submitted, 199 1. 
Stone, R.S., and J.D. Kahl, Variations in boundary layer propenies 

associated with clouds and transient weather disturbances at the 

South Pole during winter. J. Geophys. Res., 96(D3), 5137-5144, 

1991. 

Sturges, W.T., and L.A. Barrie, Chlorine, bromine and iodine in 

Arctic aerosols, Atmos. Environ. 22, 1179- 1194, 1988. 

Sturges, W.T., R.C. Schnell, S. Landsberger, J.M. Harris, and S.-M. 

Li, Chemical and meteorological influences on surface ozone 

destruction at Barrow, Alaska during spring 1989, Atmos. 

Environ., submitted, 1991. 

Walter, B., and J. Overland, Aircraft observations of the mean and 

turbulent structure of the atmospheric boundary layer during 

spring in the central Arctic, J. Geophys. Res., 96(C3), 

4663-4673. 1991. 

80 
9. Cooperative Programs 

Continuous Aerosol Monitoring with the Epiphaniometer at MLO 

U. BALTENSPERGER, H.W. GAGGELER, AND D.T. JOST 

Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland 

An epiphaniometer has been operating at MLO since 

December 1989. This instrument was developed recently 

[Gaggeler et al., 1989] and has the ability for continuous 

aerosol monitoring even at very low aerosol concentrations 

[Baltensperger el al., 1991]. Due to the low flow rate of 

1.0 L min- 1, the device consumes only 8W of power, 

including counting and data processing. It is, therefore, 

suitable for battery operation, and it has been used together 

with a solar panel for continuous aerosol measurements in 

the Swiss Alps at elevations up to 4450 m. [Baltensperger 

et al., 1991]. 

The system is described in detail by Gaggeler et al., 

1989. Aerosols are pumped through a chamber containing 

radioactive lead isotopes (211Pb). These single lead atoms 

are produced at a constant rate by the decay of a short-lived 

radon isotope (219Rn) emanating from a Jong-lived actinium 

source (227Ac). 211Pb atoms attached to aerosol particles 

are transported through a capillary acting as a diffusion 

barrier for non-attached lead atoms. At the end of the 

capillary, the aerosol particles and with them the attached 

lead atoms are deposited on a filler. The resulting activity 

on the filter is measured continuously by a surface barrier 

detector via the cx-decay of 211Bi, the daughter of 211 Pb. 

Due to the relatively short half-life of 211 Pb, the device 

allows continuous monitoring of aerosols, without changing 

or transporting the filter. 

Calibration experiments with artificial aerosols showed 

that the attachment coefficient of the 2 11 Pb atoms can be 

described by the Fuchs theory of coagulation [Pandis et al., 

1991]. Since the device delivers a signal which is 

5.0 

- Ep'.phoniometer ..., epr.e :f""Et~ 

2 4.5 60 ....... c 4.0 "i :::J E 0 

0 50 3.5 n 

I 

0 0 

40 3.0 .._, 

\... 2.5 \... 

Q) 

~ 30 .LJ Q; Q) 2.0 E E 

Q 1.5 .2 20 Q) c .<:: 0 1.0 a. .<:: Q) a. 10 z ·a. 

w 0.5 

0 0.0 

1. 3. 5. 7 9. 11 . 13 15. 17. 19. 21. 23. 25. 27. 29. 31. 

Fig. I. Epiphaniometer and nephelometer (A= 450 nm) data from 

MLO for July 1990 (G:vlT). 

proportional to the "Fuchs surface" of the aerosol particles, it 

was called epiphaniometer (the Greek word epiphania small 

aerodynamic diameters (d<lOO nm) the epiphaniometer 

means surface of a body) [Gaggeler et al., 1989]. Thus at 

signal is roughly proportional to the surface area of the 

aerosol particles. At large aerodynamic diameters (>3 μ m) 

the signal is proportional to d. In the intermediate regime, 

the obtained signal is proportional to dx, with x varying 

between 1 and 2, depending on particle diameter. Thus the 

Fuchs surface of an aerosol particle can be viewed as an 

intermediate moment between its diameter (first moment) 

and its surface (second moment). Generally the 

epiphaniometer data alone are not sufficient for the 

calculation of other moments like number, surface, or 

volume in the same way that a CNC can provide only 

number concentration and not any other moments. However, 

for an aged aerosol usually found at remote locations good 

correlations are normally found between epiphaniometer 

signal and mass concentration [Baltensperger et al., 1991 ]. 

Therefore, good agreement between epiphaniometer and 

nephelometer data should be expected at MLO. 

During 1990, the epiphaniometer was running with very 

few interruptions, mainly caused by power failures. With 

the chosen time resolution of 30 minutes the lowest value 

found for this year was still nearly two orders of magnitude 

above the detection limit, demonstrating the excellent 

sensitivity of the instrument. As an example, Figure 1 

shows the epiphaniometer data along with the nephelometer 

data (for :>-.! = 450 nm) from MLO for July, 1990. Very 

good agreement is found with a correlation coefficient r = 

81 

16000 - Jan 90 

14000 . - Feb 90 

' i: - Mar 90 12000 c: <> Apr 90 ! 10000 . .,.. May 90 

M - Jun 90 ~ 

~ 8000 Q. -- Jul 90 

!l 6000 --Aug 90 c: 

" - -Sep 90 0 

'-' 4000 -0-0cl 90 

2000 "'-Nov 90 

-- Dec 90 

0 

14:00 18:00 2200 02:00 10:00 14:00 

Local Time (HST) 

Fig. 2. Diurnal variations of the cpiphaniometer signal from MLO 

averaged over each month of 1990. 
0.955 for this month. This is true for the usual diurnal 

variation found at MLO (as shown, e.g. on July 9) as well 

as for the special episode with high aerosol concentrations 

between July 1 and 7. The correlation with CNC data for 

this month was worse (r = 0.54). During most of the period 

July 1 through 7, number concentrations were below 500 

cm·3. Thus downslope conditions along with a CNC 

reading of less than 500 cm·3 are not a secure indication for 

low aerosol concentrations, and nephelometer or 

epiphaniometer data might be used to define clean 

background conditions. 

Figure 2 shows the diurnal variations averaged over each 

month of 1990. It can be seen that the minima of these 

variations are rather constant during the year (with the 

exception of July, which showed the exceptional episode 

described above). On the other hand, the maxima show a 

higher variability depending on the meteorological 

conditions of the corresponding month. On an average, the 

minima during downslope conditions (0730-0900 LST) 

correspond to 60 % of the annual mean. For the fine aerosol 

mass concentration, Cahill et al. [1990) found a downwind 

value of 80% compared to the annual average. Taking into 

account the concentration decrease between 0000 and 0900 

LST (Figure 2), this is in reasonable agreement with our data. 

Acknowledgments. We thank E. Robinson and A. Yoshinaga for 

their cooperation and surveillance of the epiphaniometer, and B. 

Bodhaine for providing the nephelometer and CNC data. 

REFERENCES 

Baltensperger, U., H.W. Gaggeler, D.T. Jost, M. Emmenegger, and 

W. Ngeli, Continuous background aerosol monitoring with the 

epiphaniometer, Atmos. Environ. 25A, 629-634, 1991. 

Cahill, T.A., L.K. Wilkinson, and R.A. Eldred, Chemical resolution 

of fine aerosol mass at MLO: The role of organic matter, in 

Climate Monitoring and Diagnostics l.Aboratory, No. 18: 

Summary Report 1989, edited by W.D. Komhyr and R.M. 

Rosson, pp. 88-91, NOAA Environmental Research Laboratories, 

Boulder, Colorado, 1990. 

Gaggeler, H.W., U. Baltensperger, M. Emmenegger, D.T. Jost, A. 

Schmidt-Ott, P. Haller, and M. Hofmann, The epiphaniometer, a 

new device for continuous aerosol monitoring, J. Aerosol Sci., 

20 , 557-564, 1989. 

Pandis, S.N., U. Baltensperger, J.K. Wolfenbarger, and J.H. 

82 

Seinfeld, Inversion of aerosol data from the epiphaniometer, J. 

Aerosol Sci., 22, 417-428, 1991. 
Antarctic Ultraviolet Spectroradiometer Monitoring Program 

C.R. BOOTH, T. LUCAS,], MORROW, D. NEUSCHULER, J. TUSSON, AND]. YEH 

Biospherical lnstrwnents Inc ., San Diego, California 92117 

1. INTRODUcnON 

The Antarctic Ultraviolet Spectroradiometer Monitoring 

Network was established by the United States National 

Science Foundation (NSF) in 1988 in response to predictions 

of increased UV radiation in the polar regions. The network 

consists of a number of automated, high resolution 

spectroradiometers placed in strategic locations in Antarctica 

and the Arctic (Table 1). The network makes essential 

measurements of UV irradiance and provides a variety of 

biological dosage calculations of UV exposure. Biospherical 

Instruments Inc. (San Diego, California), under contract to 

Antarctica Support Associates (ASA), directed by NSF, is 

responsible for providing engineering and operating support 

and distributing data to the scientific community. 

2. METHODOLOGY 

The spectroradiometer system consists of two main 

subassemblies: the Scanning Monochromator Detector 

Assembly (SMDA) and the Process Control Assembly 

(PCA). The SMDA collects the downwelling irradiance, and 

the PCA acquires and stores these data. 

The SMDA contains an irradiance diffuser, monochromator, photomultiplier tube (PMT). and calibration 

lamps. UV irradiance passes through a Teflon diffuser and is 

directed by a beam splitter through a 0.1 m double monochromator to the PMT detector. Tungsten-halogen and 

mercury vapor lamps are used for internal calibration of the 

optical pathway. In order to minimize noise, the monochromator and PMT are located in individual temperaturecontrolled subassemblies. 

A series of additional sensors are scanned simultaneously 

with the PMT and between the high resolution PMT scans. 

These provide reference data that can be used to track 

instrument operation and can also be used to normalize data 

for time varying changes in atmospheric conditions and 

system responsivity. 

TABLE 1. Installation Sites 

Site Longitut<le Latitude Established Location 

McMurdo 166.40'E 77.5 l'S March 1988 Arrival 

heights 

Palmer 64.03'W 64.46S May 1988 Clean Air 

Building 

South Pole 0 90.00'S Feb. 1988 Clean Air 

Building 

Ushuaia, 68'W 54.59'S Nov. 1988 CA DIC 

Argentina 

Barrow, 156.6l 'W 71.32'N Dec. 1990 

Alaska 

Typically this assembly is located on a building rooftop, 

away from obstructions. Only the irradiance collector and 

auxiliary sensors are located outdoors. Twice per month a 

calibration lamp fixture containing a Standard of Spectral 

Irradiance is mounted by the site operator atop the SMDA 

and a high resolution scan is performed. Following 

immediately, a scan of the internal tungsten-halogen source 

transfers the absolute calibration to the internal source. 

The SMDA is controlled and data is acquired by the PCA. 

This assembly, located up to 50 feet from the SMDA, 

includes a personal computer and monitor, power control 

panel and supplies, precision voltmeter, and microcomputercontrolled peripheral interface modules. In addition to data 

acquisition, the computer processes UV irradiance measurements and performs intermediate calibrations automatically. 

Human attention is required only for data transfer, periodic 

manual absolute calibrations, and maintenance of the system. 

3. R ESULTS 

The amount of short wavelength ultraviolet radiation 

incident on the earth is governed by several factors. Solar 

angle, cloud cover, and atmospheric gas concentration are 

the main factors. Although 1988-1990 showed considerable 

depletion of the ozone layer over Antarctica, the geographical distribution of the ozone hole as a function of time 

varies. A dramatic comparison of the impact of ozone 

depletion is seen in Figure 1. Here we compare spectral 

scans recorded at McMurdo at the same time on October 20 

for 1988, 1989, and 1990. For this calendar day in 1988, the 

TOMS satellite reported total column ozone concentration of 

386 Dobson Units (DU), a relatively high level; it was 161 

DU in 1989; and 179 in 1990, with all years showing 

considerable temporal variation. Note that this calendar day 

was selected because of the wide range of readings that 

83 

100 ~-- -------- -------- ---

.. ~-------.; :.;_:.; :.::.::;-~·· 

E 

$ 

E 

~ "' 0 ' 

.····1 r'-;.,_4'- .. ,. .. / ... .. '/ 

_.,, , .. , 

•/ 

.. , ... _ . ., __ 

0001 

., .", ;, 

~ ...... 

Wovtlen9'11 (nm) 

.. . ~ :..· ;." : ..::. ·..: .. _; : ... : :.: ;.· . 

~~.:: 1 

Fig. I . Spectral irradiance as measured at McMurdo for October 20, 

1988, 1989, and 1990. 
occurred on this day over the 3 years. This wide range is not 

in itself indicative of annual trends in either ozone depletion 

or UV exposure al Antarctica. 

To compare UV irradiances from the northern and 

southern polar regions, we selected data from sunrise to the 

solar maximum and expressed the time series in terms of the 

increasing solar zenith angle that is experienced during the 

spring as the sun progressively gets higher. This method of 

presentation compensates for the effect of sun angle on the 

measured irradiance. For the 1990-1991 "Ozone Hole 

Season," there are marked differences between the two 

example sites (Figure 2). McMurdo experienced generally 

larger integrated UV-B irradiances compared to Barrow as 

well as greater variability. This variability is indicative of 

the strong transient depletion in atmospheric ozone concentration experienced over McMurdo that was not experienced over Barrow. In considering the entire solar UV 

region of the spectrum, the observations are increasingly 

different as we examine shorter wavelengths. 

Solar Zenith Angle 

Fig. 2. Integrated UV-B irradiance (290-320nm) during the 

springtime for Barrow, Alaska and McMurdo, Antarctica, for a 

variety of solar zenith angles. 

2.00E-01 

1.eoE-01 

1 60E-01 

1.40E-01 

E 1.20E-01 

~ 1.00E-01 

"- 8.00E-02 

6.00E-02 

4.00E-02 

2.00E-02 

--- McMurdo 

--- - Barrow 

OOOE +ool--~- --~~..:.:.:::....:==.~:;_....:::=--

45 SS 75 85 95 

Solar Zenith Angle 

Fig. 3. Integrals (290-320nm) of D~A dose weighted irradiances 

[Set/ow, 1974) for Barrow, Alaska and McMurdo, Antarctica, for a 

variety of solar zenith angles. 

Most of the concern over ozone depletion has arisen due 

to the prediction that the resulting high levels of UV would 

have significant biological impact. The spectral expression 

of this impact is commonly called the dose weighting or 

action spectra weighting. Figure 3 shows the integral of the 

product of irradiance spectra as shown in Figure 1 and the 

DNA damage action spectra as determined by Set/ow [ 1974], 

also as a function of solar zenith angle. The total UV dosage 

that an organism with a similar spectral susceptibility would 

receive can be expressed by this integral. For the most 

recent ozone-hole season, there was marked contrast in DNA 

dose weighted irradiance between McMurdo and Barrow for 

similar solar zenith angles. McMurdo experienced considerably higher DNA dose irradiances during the spring as well 

as significant local temporal variability as compared lo 

Barrow. 

4. SUMMARY 

The establishment of a monitoring network for UV 

radiation has been a critical parl of the United States 

Antarctic Program. Its purpose is to evaluate the consequences of stratospheric ozone depletion on the health and 

productivity of Antarctic organisms and personnel. Data 

products resulting from this network include analyses of 

various measures of UV, including UVB, unweighted 

spectral integrals, and a variety of biologically weighted 

dosages. This monitoring network supports scientific 

researchers in Antarctica, and has prov ided independent 

confirmation of the role of the ozone layer in moderating UV 

solar irradiance. 

Acknowledgments. This research and monitoring activity was 

funded by contract AOTOOOlO to Biospherical Instruments from 

Antarctic Support Associates (ASA). Dr. A. Kruger of NASA/ 

GSFC provided TOMS Total Ozone data for comparison purposes. 

Prior to December 1990, the South Pole installation was the 

responsibility of NOAA personnel including J. Lowell and M. 

O'Neill. From December 1990 on, the system operation has been 

the responsibility of S. Redick of ASA. Barrow operators include 

Dr. D. Norton, D. Roghair, and NOAA/CMDL personnel D. Endres 

and C. Churylo. 

Special thanks goes to Dr. Steve Kottmeier of ASA (and 

formerly JTT-A/l:S) who works with us on a daily basis to make it 

possible to accomplish this project in Antarctica. Data from the 

NSF UV Spectroradiometer Network is available to all qualified 

researchers. NSF grantees have priority access to these data. For 

more information, please contact: Dr. Polly Penhale, Division of 

Polar Programs, National Science Foundation, 1800 G St. N.W., 

Washington, D.C. 20550. 

5. REFERE~CE 

Setlow, R.B., The wavelengths in sunlight effective in producing 

skin cancer: a theoretical analysis, Proceedings, National 

Academy of Science, 71(9), 3363-3366, 1974. 

84 
A Case Study of the Stable Lower Atmospheric Boundary Layer at Barrow, Alaska 

TAK KEE CHEUNG 

Institute of Marine & Coastal Sciences, Rutgers University, New Brunswick, New Jersey 08903 

In late March and early April 1990, an experiment was 

performed at BRW. The main purpose of the experiment 

was to investigate what atmospheric phenomena are present 

under stable conditions in the Arctic and to field test, under 

winter conditions, the equipment that will be deployed in a 

future Arctic leads experiment (LEADEX) scheduled for 

1992. Short time-scale atmospheric phenomena are of 

special interest here because the time scale of a lead is 

relatively short and is on the order of hours, or at the most a 

day or so; the spatial scale varies from meters to hundreds of 

meters wide and kilometers to tens of kilometers Jong [Smith 

et al., 1990]. 

A monostatic sodar with real-time facsimile output was 

the primary instrument. In the monostatic (backscatter) 

mode, the sodar facsimile record provides a vertical profile 

of the intensity of small-scale temperature fluctuations 

[Little, 1969). These fluctuations are generally associated 

with turbulence within regions of non-zero potential 

temperature gradient. Thi;s various atmospheric 

phenomena, such as temperature inversions and wave 

perturbations, can easily be detected by the sodar. 

Radiosondes were launched twice daily and were generally 

set to relatively low ascent rates (using 100-g balloons) to 

increase the vertical resolution of meteorological data. A 

tethered sonde system was deployed whenever conditions 

allowed (e.g., clearance from the local airport). The 

tethered balloon reached an altitude of about 1 km during 

its flights. Other data from the observatory tower such as 

wind speed and direction (at 17 m), pressure (9.5 m MSL), 

and air and dewpoint temperature (3 m) were averaged 

hourly and recorded. 

The mean temperature hovered near approximately - l 6'C 

during the experiment, and daily temperature variations were 

between 5-12'C. This mean temperature is warmer than 

normal for late March and early April at BRW (e.g., the 

monthly mean temperature for March is -26'C from 

climatological records). The wind came mostly from the east 

or east northeast, which is the prevailing climatological wind 

direction. A strong temperature inversion persisted 

throughout this experiment. The temperature difference 

across the inversion varied between 8-13 'C. Multiple 

inversion layers were observed in several soundings. With 

few exceptions, the stronger inversion layers were elevated. 

However, thin surface-based inversion layers with heights 

less than 150 m were frequently observed. In all soundings, 

major inversions seem to be confined to below 1.5 km. The 

temperature soundings are consistent with climatological 

data [Kahl, 1990]. 

A wide range of phenomena were recorded, including a 

solitary-like wave train similar to those observed by Cheung 

and little 1990 (see their Figure 16). This is the only 

gravity wave train of this type recorded during the 

experiment; it is unclear whether this is an indication of the 

frequency of occurrence of such events in this region. 

Multiple scattering layers (each at 6-10 m thick) were 

observed. During such time, even with a moderate wind 

speed near the surface, there appeared to be little 

perturbation of the boundary layer. The near-surface 

temperature was usually very cold during such occurrence. 

This may explain the Jack of features other than the mostly 

unperturbed strata in an overall strongly stable stratification. 

Most of the visible changes were confined to within adjacent 

layers or within individual layers, which is another 

indication of strong stable stratification. Thus any 

shear-generated instability was at most strong enough to 

produce changes or mixing within adjacent layers. 

The sodar also detected breaking waves as evidenced on 

the facsimile record by the braided structure characteristic of 

this type of event. High wind speed is usually observed with 

these breaking wave structures and is consistent with the 

results of similar observations. Vigorous mixing caused by 

continual wave breaking and turbulence generation beneath 

the inversion could explain the near-neutral conditions and 

the diffuse sodar return so often observed in the Arctic 

winter surface boundary layer [/lolmgren and Spears, 1974]. 

A simple order-of-magnitude estimate indicates that the 

waves are indeed due to Kelvin-Helmholtz instability. 

Additional cases as documented in Cheung [ 1991] are all 

just "snapshots" of the wide variety of activities that can 

occur during winter at BRW and probably along the Alaskan 

coast. Shear-generated Kelvin-Helmholtz instability seems 

to be the prominent mechanism in these chosen examples. In 

the absence of solar heating during Arctic winters, 

Kelvin-Helmholtz instability and the possible triggering of 

such instability by passing gravity waves, appear to be the 

dominant mechanisms in small-scale (meters to hundreds of 

meters) overturning and generation of centimeter-scale 

turbulence within the near-ground boundary layer. This 

mixing close to the surface may also explain why elevated 

inversion layers are often observed during Arctic winters. 

The transition from one case to another is very gradual as 

reported by /lolmgren a11d Spears [1974]. 

The mesoscale or synoptic-scale activity may also 

influence the events described here. It is unclear if the 

low-level jet so often observed at BRW is associated with 

the processes described by Kozo [ 1980] and Dickey [ 1961]. 

Neff and l/a/J [1976] and Neff [1980) certainly claimed 

synoptic-scale influences for their observations in 

Antarctica. 

Given the Jack of local orography and the slowly changing 

synoptic conditions at BRW, it is quite surprising to find 

such a wide assortment of atmospheric structure and 

dynamics. In 1992, we plan a more comprehensive study on 

the pack ice 100-300 km from Prudhoe Bay as part of 

85 
LEADEX. The effects of open and newly frozen leads will 

be one of the primary objectives of the experiment. Besides 

a sodar, the radiosondes, and the tethered balloon used in the 

present study, further investigation of the Arctic boundary 

layer will encompass additional instruments, e.g. lead-site 

portable sodars, a UHF wind profiler with thermodynamic 

profiling capability (the radio acoustic sensing technique 

described by May el al., 1989a,b) and a surface pressure 

array. Preliminary results from a pilot experiment near 

Prudhoe Bay in April 1991 indicated that these instruments 

performed well in the cold near a lead. 

Acknowledgments. The author gratefully acknowledges the 

assistance of Scott Abbot, Catherine Russell, and Dan Wolfe 

in the planning, preparation, and implementation of the 

experiment. The BRW personnel provided invaluable 

logistics support for the experiment. The encouragement and 

support of C. G. Little and W. D. Neff made this study 

possible. The University Corporation for Atmospheric 

Research supported the research with funds supplied by the 

Atmospheric Directorate of the Naval Oceanographic and 

Atmospheric Research Laboratory, Monterey, California. 

REFERENCES 

Cheung, T. K., Sodar observations of the stable lower atmospheric 

boundary layer at Barrow, Alaska, Boundary.Layer Meteorol., in 

press, 1991. 

Cheung, T. K. and Little, C. G., Meteorological tower, 

microbarograph array, and sodar observations of solitary-like 

waves in the nocturnal boundary layer, J. Atmos. Sci., 47, 

25 16-2536, 1990. 

Dickey, W.W., A study of a topographic effect on wind in the Arctic, 

J . Meteorol. 18, 790-803, 1961. 

Holmgren, B. and Spears, L., Sodar investigation of the effect of open 

leads on the boundary layer structure over the Arctic basin, 

AJDJEX Bulletin, 27, 167-17 9, 1974. 

Kahl, J. D., Characteristics of the low-level temperature inversion 

along the Alaskan Arctic Coast, Int. J. Climat. JO, 537-548, 1990. 

Kozo, T. L., Mounta in barrier baroclinity effects on surface winds 

along the Alaskan Arctic Coast, Geophys. Res. Lett. 7, 337-380, 

1980. 

Little, C. G., Acoustic methods for the remote probing of the lower 

atmosphere, Proceedings, IEEE, 57, 57 1-578, 1969. 

May, P. T., Moran, K. P., and Strauch, R. G., The accuracy of RASS 

temperature measurements, J. Appl. Meteorol., 28, 1329-1384, 

1989a. 

May, P. T., Strauch, R. G., Moran, K. P., and Ecklund, W. L., 

Temperature sounding by RASS with wind profiler radars: A 

preliminary study, IEEE Trans. Geosci. Ref1Ulte Sens., 28, 19-28, 

1989b. 

Neff, W. D., An observational and numerical study <Jf the atmospheric 

boundary layer overlying the East Antarctic Ice Sheet, Ph.D. 

dissertation, University of Colorado, Boulder, 272 pp., 1980. 

Neff, W. D. and Hall, F. F., Acoustic Sounder Measurements of the 

South Pole Boundary Layer, Preprint Volume -17th Radar 

Meteorological Conference, American Meteorological Society, 

Boston, 297-302, 1976. 

Smith, S. D., Muench, R. D., and Pease, C. H., Polynyas and Leads: 

86 

An Overview of Physical Processes and Environment, J. Geophys. 

Res., 95, 946 1-9479, 1990. 
Artificial Windshielding of Precipitation Gauges in the Arctic 

GEORGE P. CLAGETT 

Soil Conservation Service, Anchorage, Alaska 99501 

1. INTRODUCTION 

Precipitation gauges can provide good measurements of 

the water equivalent of snow precipitation, provided the 

gauge is protected or shielded from wind effects. 

Unfortunately, there are no standards for collecting snow 

prectpttation. Gauges located in exposed and windy areas 

may be totally unshielded, partially shielded by one or more 

buildings, or equipped with one of several types of artificial 

shields. The various shielding options in common use, 

therefore, produce a wide range of gauge catch efficiency. 

Also, the various studies of artificial shields in the United 

States and Canada have produced a wide range of results. 

This must be, in part, due to the wide range of weather 

conditions under which the various studies have been 

conducted. A lingering problem is applying the results to the 

local conditions of Alaska's tundra regions. 

2. METHODS 

A study of the windshield alternatives, under the unique 

conditions of Alaska's Arctic coastal region, was set up at 

the CMDL facility at BRW during September 1989. 

Snowfall catches from four newly installed precipitation 

storage gauges were compared with that from an existing 

storage gauge protected by a Wyoming shield [Hanson, 

1988). Two of the new gauges were shielded-one with a 

Nipher shield [Goodison et al., 1983) and the other with an 

Alter shield [Alter, 1937]-and two were unshielded. One of 

the unshielded gauges was serviced on an event basis, the 

same as the three shielded gauges. The other unshielded 

gauge was treated as if it were a remote gauge, allowing rime 

to build up and dissipate naturally to see what effects rime 

had on the overall catch. The four newly installed gauges 

are 20.3 cm in diameter x 100 cm tall, mounted with the 

orifice 2 m above the normal ground surface. The existing 

Wyoming-shielded gauge is 30.5 cm in diameter x 2 m tall, 

and is equipped with a Leupold-Stevens water-level recorder. 

3. R ESULTS 

The 1990-1991 winter season, and second year of the 

study, was marked by a plumbing line blockage between the 

Wyoming-shielded precipitation gauge and the recording 

system. Seasonal totals were available for comparison 

between the Nipher, Alter, and unshielded gauges, however. 

Provisional results for the period October 18, 1990, to May 

3, 1991, are as follows: the Nipher-shielded gauge caught a 

total of 39.6 mm snowfall moisture during the period. The 

Alter-shielded gauge caught 12.7 mm or 32% of the 

Nipher-shielded gauge. The unshielded but serviced gauge 

caught only 4.8 mm or 12% of the Nipher-shielded gauge. 

The unshielded and non-serviced gauge appears to have been 

leaking through the spring months. The results continue to 

confirm the unshielded and/or Alter-shielded gauges catch 

only one-third or less of the catches of Nipher-shielded (or 

Wyoming-shielded) gauges. 

Acknowledgment. Appreciation is expressed to D. Endres, Station 

Chief, BRW, who serviced the precipitation gauges and collected 

the snow samples. 

4. REFERENCES 

Alter, S.C., Shield storage precipitation gauges, Mon. Weather Rev., 

65, 262-265, 1937. 

Goodison, B.E., V.R. Turner, and J.E. Metcalfe, A nipher-type shield 

for recording precipitation gauges, Proceedings, 5th Symposium on 

Meteorological Observations and Instrumentation, Toronto, 

Ontario, Canada, pp. 2-126, American Meteorological Society, 

Boston, 1983. 

87 

Hanson, C.L., Precipitation measured by gages protected by the 

Wyoming shield and the dual-gauge system, Proceedings, 56th 

Western Snow Conference, Kalispell, MT, pp. 174-177, Colorado 

State University, Fort Collins, 1988. 
UVB Monitoring Data from Mauna Loa 

DAVID L. CORRELL, CARL CLARK, RUSSELL GOODRICH, AND DOUGLASS HA YES 

Smithsonian Environmental Research Center, P.O. Box 28, Edgewater, Maryland 21037 

Our laboratory has been continuously monitoring surface 

irradiance at MLO in a series of eight 5-nm band passes in 

the UVB (290-325 nm) since the fall of 1984. Measurements 

TABLE 1. UVB Global lrradiance at MLO During Solar 

Eclipse July 11, 1991 

Time Filter Center Wavelength (nm) Ratio 

(LST) 304.9 310.8 314.7 320.2 325.3 04.9/320.2 

0700 0.0154 0.1507 0.4109 1.0144 1.8030 0.0152 

0705 0.0155 0.1440 0.3759 0.9011 1.5959 0.0168 

0710 0.0142 0.1232 0.3113 0.7178 1.2416 0.0197 

07 15 0.0118 0.0972 0.2388 0.5349 0.9072 0.0220 

0720 0.0074 0.0577 0.1374 0.3060 0.5169 0.0242 

0725 0.0024 0.0172 0.0415 0.0896 0.1478 0.0264 

0726 0.0014 0.0108 0.0245 0.0526 0.0874 0.0257 

0727 0.0007 0.0049 0.0114 0.0242 0.0387 0.0281 

0728 0.0001 0.0009 0.0020 0.0042 0.0085 0.0286 

0729 0.0000 0.0000 0.0002 0.0000 0.0001 

0730 0.0000 0.0002 0.0000 0.0000 0.0000 

0731 0.0000 0.0001 0.0000 0.0001 0.0000 

0732 0.0000 0.0000 0.0001 0.0006 0.0004 

0733 0.0002 0.0014 0.0036 0.0068 0.0111 0.0336 

0734 0.0011 0.0070 0.0155 0.0318 0.0510 0.0345 

0735 0.0023 0.0150 0.0334 0.0685 0.1100 0.0340 

0736 0.0039 0.0249 0.0545 0.1116 0.1708 0.0348 

0740 0.0129 0.0816 0. 1735 0.3461 0.5445 0.0374 

0745 0.0321 0.1930 0.3974 0.7820 1.2404 0.0413 

0750 0.0613 0.3500 0.7164 1.3957 2.1858 0.0438 

0155 0.1010 0.5613 1.1242 2.1220 3.3316 0.0476 

0800 0.1476 0.7994 1.5406 2.9276 4.4601 0.0504 

Data are I-minute averages. Units are JJM2/nm/minute. 

are made with a prects10n, accurately calibrated, spectral 

radiometer [Goldberg and Klein, 1974; Goldberg, 1982]. 

These data are now being edited and analyzed for publication. Similar data from Rockville and Edgewater, Maryland 

(39'N, 77'W) for the period from 1975 through 1990 have 

been analyzed and submitted for publication. These 

Maryland data are available in archived format on floppy 

disks with de-archiving manual and software, for SlOO. 

Requests for data and additional information should be 

directed to David L. Correll, Director, at the above address. 

The MLO spectral radiometer was operating during the 

July 11, 1991, solar eclipse. Intensities in all spectral 

channels began to decline at 0701 LST, reached zero 

irradiance at 0729 LST, remained at zero values until 0732 

LST, then increased to normal irradiance levels by 0830 

LST. Plots of various UVB wavelength irradiance ratios did 

not reveal any unexpected or abnormal spectral quality shifts 

between 0700 and 0800. Spectral radiometer data are taken 

as 72 spectral scans per minute. One-minute averages are 

recorded on the data Jogger. Excerpted data from the eclipse 

period are given in Table l. 

R EfoERENCES 

Goldberg, B., and W.H. Klein, Radiometer to monitor low levels of 

ultraviolet irradiance, Appl. Opt .. 13, 493-496, 1974. 

Goldberg, B., Radiometric measurements in the UV-B region of 

daylight, in The Role of Solar Ultraviolet Radiation in Marine 

Ecosystems, edited by J. Calkins, pp. 121-129, Plenum, New 

York, 1982. 

88 
South Pole Lidar 

G . Frocco, M. CACCIA:\'I, P. DI GIROLA'.\.10, A. DI SARRA, A~D D. FUA 

Universita "la Sapienza" 00185 Roma, ltaly 

J. DE LUISI 

NOAA, Climate Monitoring and Diagnostics laboratory, Boulder, Colorado 80303 

1. l:\TRODUC110N 

A lidar has been operational at the Amundsen-Scott South 

Pole Observatory (SPO) since December 1987; it was 

installed as a cooperative project between the University of 

Rome and CMDL. The lidar is, in principle, capable of 

measuring vertical profiles of the volume backscattering 

cross-section of the atmosphere al the wavelength 532 nm in 

a height region extending from the boundary layer to the 

upper stratosphere. With these measurements it is possible 

to infer the molecular and aerosol concentration of air and to 

derive, under some conditions, other quantities such as 

atmospheric temperature. 

The information obtained is relevant to studies of 

atmospheric radiation, slmcture and composition, and may 

be of particular interest in studies of the ozone hole depiction 

process. It is worth pointing out that in the polar night the 

lidar, being an active instrument, has distinct advantages 

when compared to other remote sensing techniques. 

Possible information is categorized as follows: boundary 

layer aerosols; tropospheric aerosol~; tropospheric clouds; 

stratospheric aerosols; stratospheric clouds; molecular 

density and stratospheric temperature; and gravity waves. 

2. EXPERIMENTAL DETAILS 

The system was installed in the Clean Air Facility (CAF) 

facing the SPO dome. A hatch, with a clear opening of 

approximately 0.9 m x 0.9 m, equipped with glass plates, 

permits zenith observations. The main characteristics of the 

lidar arc given in Table 1. The data are stored in a binary 

form on a computer hard disk that is backed up periodically 

TABLE l. Characteristics of the South Pole Lidar 

Characteristics 

Wavelength 

Pulse energy 

Pulse duration 

Pulse repetition rate 

Receiving telescope 

Transm. beam divergence 

Filter bandwidth 

Venical resolution 

Photomultipliers 

Data acquisition 

532nm 

300 mJ nominal 

20ns 

4 Hz 

0.5 m diam. 

0.3 mrad 

!nm 

75 m 

Value 

Cooled and gates 11 dynode EMI 

CA.\tlAC+GPlll+286 based computer 

by mmllape cartridges. During the winter compacted and 

fom1aued data, representing half-hour averages, arc ttansmiued 

through the ATS-3 satellite link. The entire data set is 

physically carried to the University of Rome at station opening 

each November. 

Over the years the data acquisition system has had several 

changes to improve its performance and reliability. In 

particular, two channels for the measurement of the depolarization were added. 

3. OPERATION 

System operations have been taken care of by the winter-over 

personnel of CMDL with support from ASA personnel; during 

1990 the system was operated by personnel from the University 

of Chicago. University of Rome personnel provide maintenance 

of the instrument each summer at SPO. 

The system installed al SPO experienced a few unexpected 

problems, mostly originating from an underestimation of the 

temperature variability within the CAF. On more than one 

occasion the coolant inside the laser head froze, thus requiring 

major repairs involving substitution of various optical clements 

and realignment of the system. This job requires a degree of 

skill not normally available in the field. The origin of the 

trouble was discovered in retrospect, and during the austral 

summer 1990-1991, the problem was solved by improving the 

temperature stability inside the lidar room and rearranging the 

instrument so that the water pipes run as high as possible above 

the cold floor. 

89 

Measurements were carried out for a total of 19 days during 

May-October 1988, 55 days during November 1989-Novcmber 

1990, and more than 50 days during the period November 

1990-Scptember 1991. 

Recently, the operation of the laser has been kept at lower 

levels to assure conservative use of the laser, and during the 

current year no failures were reported to date. 

4. RESULTS 

In view of the reduced power levels that the system 

utilized, the work has concentrated on targets of relatively 

large cross-section. The observations have yielded significant data on polar stratospheric clouds. So far the only set of 

data that has been analyzed to some degree of detai l arc 

those of 1988, while the analysis of the 1989-1990 and 

1990-1991 sets is in progress. The analysis has permitted 

completion of several studies, some already published and 

some in the process of review. 
Fiacco et al., [ 1989) describes interesting correlations 

between peaks of the lidar backscattering profiles and 

relative minima of the ozone profiles. 

Aerosol layers, generically identified as Polar 

Stratospheric Clouds (PSCs) were frequently observed in the 

period May-October 1988 throughout the altitude range 8-20 

km. A recent paper Fiacco et al. [1991a] studied the 

temperature dependence of the lidar echoes from PSCs and 

suggested that the sensitivity of the lidar backscattering to 

temperature may define a criterion for cloud type identification. It was concluded that Type I PCs show a modest 

sensitivity to temperature and produce relatively diffuse 

echoes, while Type II PSCs show a larger sensitivity to 

temperature and produce backscattering values concentrated 

in sharply defined layers. 

On the basis of the previous work, the behavior of the 

aerosol backscattering cross-section B. has been related to the 

temperature T through linear fits between the two variables 

[Fiacco et al., 1991b]. The resulting coefficients, namely the 

slope b = dB.fdT and T ,. the temperature where the onset of 

10'------------------..273 

103 250 ., 

·;: -l 

n ~ 3 

~ ~ I! 227 ~ Ji 101 !; 

< .n 

·~ ;.:: 

c 

!! 204 ..s 10 

L.__.jL-------, .,-- ----:-~:-:---- '-:-::-=-- 1 5000 10,000 15,000 20,000 

Altitude, m 

Fig. 1. Lidar echo (upper curve) superimposed to the computed 

molecular component of the signal, and atmospheric temperature profile 

(lower curve) obtained from radiosonde data for August 26, 1988. 

condensation occurs, help to classify these clouds as Type I 

or Type II in view of the thermodynamic properties of the 

condensing species. A strong dependence of B. on T, 

represented by a large value of b, is interpreted as evidence 

of ice condensation and leads to identify the cloud at Type 

II, while a lower value of b, characteristic of diffuse 

structures, is taken as evidence for Type I clouds composed 

of nitric acid trihydrate. The evolution of these features is 

reported in a companion paper [Fua et al., 1991]. Type II 

clouds, appearing as sharp layers of moderate vertical extent, 

are almost always present in the interval from June to early 

September. The temperature at the base of the lowest layer 

spans from an initial value around 198 K to a final value in 

September around 196 K, with a corresponding height value 

from around 1.5 km to 10.5 km. Layers that we identify as 

Type I clouds appear at higher temperatures with an onset at 

the beginning of the season around 200 K to a final value at 

mid-October around 203 K. Figure 1 shows a lidar echo for 

August 26, 1988. The figure also shows the temperature 

profile for the same day as well as the profile for the 

molecular echoes. Backscattering ratios are as large as 5. 

Large changes in the echo intensity appear to be associated 

with little changes in the temperature, characteristic of Type 

II PSCs. This is related to the large amount of condensable 

substance mobilized by a small change in temperature: 

particle sizes of several microns can be inferred. The 

extinction of the lidar signal after traversing the cloud layer 

is too small to be estimated, which is an indication of a very 

modest vaue for the optical thickness (<0.1). 

5. R EFERENCES 

Fiocco, G., W. Komhyr, and D. Fua, Is ozone destroyed during the 

Antarctic polar night in the presence of polar stratospheric 

clouds?, Nature, 341 , 426-427, 1989. 

Fiocco, G., D. Fua, M. Cacciani, and P. Di Girolamo, On the 

temperature dependence of polar stratospheric clouds, Geophys. 

Res. Lell., 18, 424-427, 1991a . 

Fiocco, G., D. Fua, M. Cacciani, P. Di Girolamo, and J. Deluisi, 

Stratospheric clouds at South Pole during winter 1988: 1) Results 

of the lidar observations and their relationship to temperature, 

submitted J. Geophys. Res., 199 1b. 

Fua, D., M. Cacciani, P. De Girolamo, G. Fiacco, and A. di Sarra, 

Stratospheric clouds at South Pole during winter 1988: 2) Their 

evolution in relation to atmospheric structure and composition, 

submitted J. Geophys. Res., 1991. 

90 
Total Nitrate Variations at Mauna Loa 

B. J. HUEBERT AND G. L. LEE 

University of Rhode Island, Graduate School of Oceanography, Narragansett, Rhode Island 02882-1197 

1. INTRODUCTION 

Much of the NO and N02 which is emitted into the 

atmosphere is converted to nitric acid vapor or aerosol 

nitrate before it is removed by dry or wet deposition. This 

conversion to nitrate is largely complete within a few days of 

the odd-nitrogen's emission, so that in remote areas such as 

at MLO, the total nitrate concentration (vapor plus aerosol) 

represents a fair estimate of the total odd-nitrogen concentration. 

With support from NSF, we have measured nitrate 

concentrations at MLO for several years to help identify the 

important sources of odd-nitrogen compounds in remote 

parts of the globe. We now measure total nitrate every night 

from the walkup tower, in collaboration with the MLO staff. 

2. MATERIALS AND METHODS 

We use a Teflon/nylon filter-pack method for collecting 

atmospheric nitrate. Since August 1988, one filter is 

exposed each night, from 2000 LST to 0800 LST. Filters are 

returned to our URI laboratory for extraction and analysis by 

ion chromatography. Our final data are sorted using three 

criteria (wind direction, humidity, and CN count) to 

eliminate those samples that have been influenced by local 

sources on the island. 

3. RESULTS AND DISCUSSION 

During our intermittent MLO sampling prior to September 

1988, we observed a sharp maximum in nitric acid and 

aerosol nitrate concentrations in the summer. The search for 

an explanation for this maximum continues to stimulate our 

science. 

The daily values for 1990 are plotted in Figure 1. The 

lowest sustained concentrations are still evident in the 

winter, with a mix of high-concentration events and clean 

periods in the spring and late summer. 

Now that our nightly sampling has completed almost 3 

full years, the same trend is evident in this data. Figure 2 

shows monthly averages of 2000 LST to 0800 LST total 

nitrate concentrations from September 1988 to July 1991. 

As is often the case when a data set finally spans several 

years, we are just beginning to see how different the annual 

cycle is from year to yeaI. While the summer maximum/ 

winter minimum ratio was about five in 1989, it appears to 

be only two or three in 1991. (All the 1991 summer data is 

not yet inc luded though, so this conclusion could change 

somewhat.) Clearly, we need to identify the climatological 

700 

600 

w 500 

t-

~ 400 tz 

> 300 t-

& 

61 122 183 244 305 366 

J....L.IAN DAY 

Fig. l. Nightly concentrations of total nitrate in 1990. 

300 

~ 

g 

z 200 

> 

& 

100 

Fig. 2. 

time. 

Monthly average total (aerosol plus vapor) nitrate versus 

differences which cause this dramatic change in the annual 

cycle of nitrate. 

4. ONGOING RESEARCH 

We are continuing our inclusive nightly sampling from the 

tower, with the help of the MLO staff. Although equipment 

failures and bad weather (preventing filter changes on the 

tower) have occasionally caused brief lapses in the data, a 

very interesting record is emerging. We hope to identify 

both the frequency and source of high-nitric events during 

the next year or so, as well as the factors that control the 

form and the range of its annual cycle. 

91 
Temperature Inversions in the Canadian Arctic 

JONATHAN D. KAHL 

University of Wisconsin, Department o/Geosciences, Milwaukee, Wisconsin 53201 

MARK C. SERREZE AND RUSSELL C. SCH~ELL 

CJ RES, University of Colorado, Boulder, Colorado 80309 

1. INTRODUCTION 

Here we describe one aspect of an ongoing project to 

acquire, assimilate and analyze all available arctic 

rawinsonde data dating back to the 1940s. Published results 

to date include studies by Kahl [1990), who examined 

temperature inversions at Alaskan Arctic stations, and 

Serreze et al. [1991), who extended Kahl's analysis to 

include inversions in the Eurasian Arctic. In this paper we 

report on our efforts to further extend our analyses of 

inversion characteristics to the Canadian Arctic. A full 

description of results are given by Kahl el al. [1991]. 

2. DATA BASE 

Historical time series of rawinsonde measurements made 

at the thirteen Canadian Arctic stations were obtained on 

magnetic tape from NCAR in Boulder, Colorado. These 

measurements consist of vertical profiles of temperature, 

moisture, wind, geopotential height and pressure throughout 

the troposphere and lower stratosphere (typically to altitudes 

of 25-30 km). The station locations are shown in Figure l. 

The stations provide reasonably good spatial coverage 

throughout the Canadian Arctic, extending from 65°N 

(Norman Wells) to 82.5'N (Alert) and from 133.S'W 

(lnuvik/Aklavik) to northwest Greenland and Baffin Bay 

(Alert and Clyde River). 

The Canadian Arctic rawinsonde data base is summarized 

in Table 1. Data records of over 30 years in length are 

available for 9 of the 13 stations. Forty-year records were 

Fig. l. Contour diagrams showing the median inversion depth (m) 

for February in the Canadian Arctic. Extrapolation beyond original 

data points has been avoided. 

available from three of the stations (Resolute, Eureka, and 

Mould Bay). The remaining four stations have a minimum 

of 10 years of available data. Between 10,000-26,000 usable 

soundings are available from all stations except Arctic Bay, 

yielding a total of 245,070 soundings in the final analysis. 

All soundings were checked for quality and completeness 

using procedures described by Serreze el al. [1991]. 

Application of the quality control procedures forced us to 

discard 10% of the approximately 270,000 original 

soundings. 

3. METHODOLOGY 

We are concerned with low-level inversions, defined as 

those with a base below the 700 mb level. Inversions arc 

identified objectively using the algorithm developed by Kahl 

[1990). This algorithm was also used by Serrezc et al. 

[1991) to examine inversions over the Eurasian Arctic. 

Briefly, the procedure is to scan each sounding from the 

surface upwards, identifying the inversion base as the bottom 

of the first layer in which temperature increases with 

altitude. The inversion top is defined as the bottom of the 

first subsequent layer in which the temperature decreases 

with altitude. Since arctic temperature profi les often exhibit 

a complicated vertical structure [BelmonJ, 1957). negativelapse layers arc frequently encountered in the lower levels of 

the sounding. If these layers are thin (with a critical 

thickness arbitrarily defined as 100 m), they arc considered 

to be imbedded within the overall inversion layer. 

Illustrative examples of this technique are given by Kahl 

[ 1990]. Inversions were found in 89% of all usable 

soundings. 

4. RESULTS 

Our results consist of descriptions of the spatially-and 

temporally-varying features of the inversion. Because the 

complete analysis is presented elsewhere [Kah[ et al., 

1991), we present only one sample result here. 

Inversions are generally surface-based in winter, with 

maximum depths and temperature differences occurring in 

February or Marc h. February is representative of 

wintertime conditions and was chosen for presentation 

because, unlike March, there is a lack of sunlight during 

the entire month. In February, inversions occur in at least 

98% of the soundings examined at all stations. During 

February the median height of the inversion base is zero 

(i.e., surface-based) at all stations except Norman Wells, 

where it is 114 m. The tendency for wintertime inversions 

to be elevated at Norman Wells may be due to its proximity 

to Great Bear Lake, where ice concentrations are slightly 

92 
TABLE 1. Summary of rawinsonde data analyzed. 

Latitude Longitude Elevation Period of No. of 

Station Name ("N) ("W) (m msl) Record Soundings 

Alert (ALT) 82.50 62.33 6• 1950-1987 23,983 

Eureka (EUR) 80.22 86.18 10 1948-1987 25,480 

Isachsen (ISA) 78.78 103.53 25 1948-1978 18,736 

Mould Bay (~DB) 76.23 119.33 12• 1948-1987 24.927 

Resolute (RES) 74.72 94.98 67• 1948-1987 25,649 

Arctic Bay (ARB) 73.00 85.30 10 1948-1957 5,660 

Sachs Harbor (SCI!) 71.95 124.73 86• 1955-1986 19,401 

Clyde River (CLR) 70.45 68.55 25• 1950-1970 13,254 

Cambridge Bay (C~B) 69.10 105.13 27 1970-1987 10,637 

Hall Beach (HLB) 68.78 81.25 8• 1957-1987 19,144 

lnuvik/Aklavik (IXA) 68.32 133.53 103 1950-1987 24,170 

Coppermine (COP) 67.82 115.08 9• 1947-1970 13,489 

Xorman Wells {NMW) 65.28 126.80 73• 1955-1987 20,540 

Total number of soundings analyzed: 245,070t 

•Reported station elevation beginning January 1, 1961. Elevations reported prior to this were slightly different. 

tThis number is 9u% of the total number of available soundings. The remaining 10% were discarded due to insufficient data quality or 

completeness (see text). 

less than in the waters of the Canadian Archipelago 

[Parkinson et al., 1987). 

The deepest inversions (Figure 1) occur at Coppermine 

(median value 1177 m) and Arctic Bay (median value 926 

m). The spatial gradient in inversion depth reflects the fact 

that the inversion is a dynamic feature controlled by a 

number of direct and indirect forcings, including solar and 

terrestrial radiation, synoptic meteorological activity (i.e. the 

passage of cyclones that can mix the boundary layer and 

break down the inversion), latent heat factors related to 

snowmelt, and the sea-ice cover over the Arctic Ocean, and 

the waters of the Canadian Archipelago. 

5. SUMMARY 

The spatial and temporal variability of the low-level arctic 

temperature inversion has been investigated using 10-40 

years o f rawinsonde data at 13 Canadian Arctic stations. 

Inversions were present in 89% of the 245,070 soundings 

analyzed. 

As reported in detail in Kahl et al. (1991]. our analysis of 

the month-to-month variability in inversion characteristics 

revealed: 

(1) Inversions at Alert, Isachsen, and Mould Bay, three of 

the four northernmost stations, are primarily surface-based 

from autumn through midspring and elevated from midspring 

through summer. At all other stations the height of inversion 

base shows a bimodal pattern with peaks in late spring and 

late summer. 

(2) At all stations the inversion depth peaks in February 

or March. Maximum median values range from 545 m at 

Clyde River to 1177 m at Coppermine. Minimum median 

inversion depths found in September, range from 212 m at 

Cambridge Bay to 457 m at Arctic Bay. The annual 

progression of inversion depth parallels the progression of 

clear-sky percentages. 

(3) The month-to-month variability in temperature 

difference across the inversion is similar to that of inversion 

depth. Maximum median values range from 14'C at Eureka 

to 5'C at Clyde River. Minimum median values of l-2'C are 

found between August and September at all stations. 

Analysis of the spatial variability in inversion 

characteristics showed: 

(1) Winter. Inversions are primarily surface-based at all 

stations. Elevated inversions are frequently found only at 

Norman Wells. The deepest inversions occur at the 

Archipelago stations Coppermine and Arctic Bay. The 

l argest temperature inversions occur at the northern stations 

Mould Bay, Isachsen, and Eureka, and at the inland/coastal 

stations Norman Wells, Inuvik/Aklavik, and Cambridge Bay. 

Inversion intensity showed a similar pattern. 

(2) Summer. Total inversion frequency generally 

increases with latitude with a local minimum observed at 

Arctic Bay. Elevated inversion frequency exhibits 

essentially the same pattern, which is expected since 

summertime inversions are mostly elevated. The height of 

inversion base shows an irregular spatial pattern. Inversion 

depth and temperature difference shows little spatial 

93 
variability, as inversions are characteristically weak in 

summer. 

6. REFERENCES 

Belmont, A.O., Lower tropospheric inversions at ice island T-3, 

J. Atmos. Terres. Phys., Special Supplement, 1957. 

Kahl, J.D .. Characteristics of the !ow-level temperature inversion 

along the Alaskan Arctic coast, Int. J. Clim., JO, 537-548, 1990. 

Kahl, J.D., M.C. Serreze, and R.C. Schnell, Tropospheric low-level 

temperature inversions in the Canadian Arctic, Atmos. Ocean, 

submitted, 1991. 

Parkinson, C.L., J.C. Comiso, H.J. ZwaUy, D.J. Cavalieri, P. 

Gloersen, and W.J. Campbell, Arctic sea ice, 1973-1976: 

Satellite passive-microwave observations, NASA SP-489, 

National Aeronautics and Space Administration, Washington, 

DC, 296 pp., 1987. 

Serreze, M.C., J.D. Kahl, and R.C. Schnell, Low-level temperature 

inversions of the Eurasian Arctic and comparisons with Soviet 

drifting station data, J . Clim., submitted, 1991. 

94 
The Historical Arctic Rawinsonde Archive 

JONATHAN D. KAHL 

Department o/Geosciences, University ofWisconsin-Mi/wauJcee, Milwaukee, Wisconsin 53201 

MARK C. SERREZE AND R USSELL C. SCHNELL 

CIRES, University of Colorado, Boulder, Colorado 80309 

1. INTRODUCTION 

This document briefly describes the Historical Arctic 

Rawinsonde Archive, compiled under support from the 

NOAA Climate and Global Change Program (Grant 

NA85RAH05066) and the Electric Power Research Institute 

(Grant RP2333-07). The archive comprises over 1.2 million 

vertical soundings of temperature, pressure, moisture and 

wind, and contains all available rawinsonde ascents from 

Arctic land stations north of 65.N from the beginning of 

record through 1987. 

For most stations, the record begins in 1957 (the International Geophysical Year), but for a few stations, 

particularly Canadian stations, the record begins in 1948; it 

is in a user-friendly, ASCII format which may be easily 

processed by most types of computers. All data have been 

passed through error-checking routines. Plans are to 

periodically update this archive as additional data become 

available. 

2. DA TA SOURCES AND COVERAGE 

Sounding data were obtained from NCAR in Boulder, 

Colorado, and NCDC in Asheville, North Carolina. Five 

original archives were used to compile our data base: 

(1) Asian Arctic, 1976-1987: Soundings from Soviet 

and Scandinavian Arctic stations, Greenland, and "Ship 

M," a moored ship in the Norwegian Sea. 

(2) Victor Starr, 1958-1963: This archive was 

compiled by Professor Victor Starr at.MIT during the late 

1960s, and contains soundings from 75 stations throughout 

the Arctic. 

(3) Canadian Stations: Soundings from regularly 

reporting Canadian Arctic rawinsonde stations. The record 

for some stations begins as early as 1948, but most stations 

started reporting regularly in the early to mid 1950s. 

(4) Alaska and Thule, Greenland: The record begins in 

1947 for Barrow, Alaska; in 1952 for Barter Island, Alaska; 

and in 1952 for Thule, Greenland. 

(5) Asian Arctic. 1962-1975: Similar to the archive (1) 

(described above), but in a slightly different original format 

and containing fewer stations. There is a considerable 

amount of data overlap between original sources. An effort 

has been made to choose the best available data from each 

original archive, based on error analyses and completeness 

of the soundings. 

A list of stations for which sounding data are available is 

presented in Table 1. In the table, an asterisk beneath a 

particular year indicates that sounding data are available 

for at least part of that year. A total of over 1.2 million 

soundings are available, covering a 30-year period for most 

stations. 

The station locations are shown in Figure 1. Note that the 

global, land-based coverage is relatively uniform with the 

exception of the lack of stations over the interior of 

Greenland. Depending on the station, soundings are available 

from one to four times daily at 0000 GMT, 0600 GMT, 1200 

GMT, and 1800 GMT. Most often, reports are available at 

0000 GMT and 1200 GMT. Prior to 1952, reporting times 

were 0800 GMT and 1400 GMT. 

3. DATA COMPILATION AND ERROR CHECKING 

In order to produce a consistent, single-format archive, it 

was necessary to perform a variety of sorting, merging, and 

quality-control tasks. The error-checking procedures first 

involved the elimination of obv ious errors such as negative 

wind speeds. All soundings were then passed through a 

seasonally-adjustable limits check to screen out gross errors. 

We recognize that our procedure may not identify all errors 

and that on occasion what we flag as errors may in fact be 

valid data. As such, we retain the original data and give the 

user the option of (1) adhering to our determination of data 

quality; (2) adhering to the quality codes present in the five 

original archives (which we have included in the final 

.... ...;• 

· .. 

" 

..·· 

.. : .. ·:, a .... : •: a 

.. D . .. ·- 6--0~ 

a . . ~ver " .. o . 

.:: · ._,. •. ft.- . 

....... 

. ';;: . ........

..

,;~i. 

. ~. 

ri . / 

~~·. ··· _: ... / i;(.l/_j . . .... :~ r:r_ .. 

... , 9)~ :. 

0 

-c· O· 

a 

. ... o q " . . . . ·9~ . . 

:>4 ... · _Q ' . 

Fig. I. Locations of rawinsonde reports contained in the Historical 

Arctic Rawinsonde Archive. 

95 
TABLE l. Summary of the Soundings Contained in the Historical Arctic Rawinsonde Archive 

STATION LAT LON # OF DATA AVAILABLE 

ID NAME COUNTRY DEG N DEG E SOUNDINGS 4 5 5 6 6 7 7 8 8 9 

----------------------------------------------------------- 8-o----5----o- ---5----o-- --5----o----5----o 

1001 JAN MAYEN 

1005 ISFJORD RADIO 

1010 ANDOYA 

1020 

1028 BJORNOVA 

1030 

1152 BOOO 

2057 16LULEA/KALLAX 

2185 

2836 SOOANKYLA 

4202 THULE AFB 

4210 UPERNAVIK 

4220 EGEDESMINDE 

4230 HOLSTEINBORG 

4231 SOR. STROM FJORD 

4310 NORD 

4320 DANMARKSHAVN 

4330 DANEBORG 

4339 SCORESBYSUND 

4340 KAP TOBIN 

4360 ANGMAGSSALIK 

20046 OSTROV HEISA 

20047 

20069 OSTROV VIZE 

20107 BARENTSBURG 

20274 OSTROV UEDINENIA 

20292 MYS CHELIUSKIN 

20353 MYS ZHELANIA 

20406 

20667 OSTROV BELYJ 

20674 OSTROV DIKSON 

20744 MALYE KARMAKULY 

20891 KHATANGA 

21358 OSTROV ZOHOVA 

21432 OSTROV KOTELNY 

21504 OSTROV PREOBRAZHENIA 

21647 MYS SHALAUROVA 

21824 BUKHTA TIKSI 

21825 OSTROV MOSTAKH 

NORllAY 70.93 -8.67 

NORllAY 78.07 13.63 

NORllAY 69.30 

0. 

NORllAY 74.52 

o. 

NORllAY 67.28 

SllEDEN 65.60 

0. 

FINLAN 67.37 

16. 12 

0. 

19.02 

o. 

14.42 

22.10 

o. 

26.65 

GREENL 76.53 ·68.75 

GREENL 72.78 -56.17 

GREENL 

GREENL 

GREENL 

GREENL 

GREENL 

68.70 -52.75 

66.92 -53.67 

67.00 -50.80 

81.60 ·16.67 

76.77 · 18.77 

GREENL 74.30 ·20.22 

GREENL 70.48 ·21.97 

GREENL 70.42 ·21.97 

GREENL 65.60 ·37.63 

SOVIET 80.62 58. 05 

SOVIET 

SOVIET 

SOVIET 

0. 0. 

79.50 

78.07 

77.50 

76.98 

14.22 

82.23 

SOVIET 77.72 104.28 

SOVIET 

SOV IET 

SOVIET 

SOVIET 

SOVIET 

SOVIET 

SOVIET 

SOVIET 

SOVIET 

SOVIET 

SOVIET 

76.95 

0. 

73.33 

68 .58 

0. 

70.03 

21908 DZHALINDA SOVIET 

73.50 80.23 

72.38 52.73 

71.98 102.27 

76.15 152.83 

76.00 137.90 

74.67 11 2.93 

73.18 143.93 

71.58 128.92 

71.53 129.92 

70.13 113 .97 

70.62 147.88 

70.63 162.40 

70. 97 181.47 

68.97 33.05 

21946 COKURDAH SOVIET 

21965 OSTROV CHETYREKHSTOLBO SOVIET 

21982 OSTROV VRANGELYA 

22113 MURMANSK 

22165 KANIN NOS 

22205 ENA 

22217 KANDALASKSA 

22271 SOJNA 

SOVIET 

SOVIET 

SOVIET 

SOVIET 

68.65 

67.60 

43.30 

31.17 

SOVIET 67.13 32.43 

SOVIET 67.88 44.13 

15561 

983 

22 

1237 

16972 

2424 

17005 

5881 

10000 

25290 

42617 

221 

16727 

12 

4 

5512 

15450 

7 

4819 

11819 

16452 

20826 

1649 

18358 

20289 

17337 

19396 

18207 

2 

8709 

17487 

13088 

16753 

15375 

18983 

20447 

18181 

19476 

2 

4 

11238 

17650 

16430 

23186 

1803 

4 

21051 

20852 

96 

****************************** 

***** * *** 

••• 

•••••• 

****************************** 

•••••• 

****************************** 

*************** 

••••••••••• 

****************************** 

************************************ 

••• •• ****************************** 

* ** * 

• • 

**************** * *** • ** * 

****************************** 

••• 

******** 

*********************** 

****************************** 

****************************** 

****** 

•••••••••••••••••••••••••••••• 

****************************** 

****************************** 

****************************** 

****************************** 

• 

****************************** 

****************************** 

****** •••••••• ************ 

*********************** ••••• 

****************************** 

****************************** 

****************************** 

****************************** 

****************************** 

* 

• • 

****************************** 

•••••••••••••••••••••••••••••• 

****************************** 

•••••••••••••••••••••••••••••• 

***** 

•• 

****************************** 

************************* 
TABLE 1. Summary of the Soundings Contained in the Historical Arctic Rawinsonde Archive - Continued 

STATION LAT LON #OF DATA AVAILABLE 

ID NA.14E COUNTRY DEG N DEG E SOUNDINGS 4 5 5 6 6 7 7 8 8 9 

----------------------------------------------------------- 8-o----5----o----5 -- --o----5----o----5----o 

22408 KALEVALA SOVIET 65.20 31.17 2 * 

22522 KEM-PORT SOVIET 64.98 34.78 5660 **************** 

23022 AHDERHA SOVIET 69.77 61.68 18284 ****************************** 

23074 DOO I NKA 

23078 NORILSK 

23130 

23146 MYS KAMENNY 

23162 

23205 MARJAN MAR 

23274 !GARICA 

23330 SALE-KHARD (OBDORSK) 

23338 POLUY 

23383 AGATA 

23418 PECHORA 

23472 TURUKHANSK 

23552 TARKO· SALE 

24125 OLENEK 

24266 VER~HOYANSK 

24343 ZHIGANSK 

SOVIET 

SOVIET 

69.40 

69.32 

0. 

86.17 

88.22 

0. 

SOVIET 68.47 73.60 

o. o. 

SOVIET 67.65 53.02 

SOVIET 67.47 86.57 

SOVIET 66.53 66.53 

SOVIET 66.27 67.87 

SOVIET 

SOVIET 

SOVIET 

SOVIET 

SOVIET 

SOVIET 

SOVIET 

25042 AYON SOVIET 

25123 NIZHNIE KRESTIY/CERSKI SOVIET 

25173 MYS SCHMIDT SOVIET 

66.93 93.47 

65.12 57.10 

65.78 87.95 

64.92 n.82 

68.50 112.43 

67.55 133.38 

66.n 123.40 

69.93 167.97 

68.80 161.28 

68.92 180.52 

67.33 168.23 

67.85 184.37 

66.17 190. 17 

65.73 150.90 

65.23 160.50 

71.30-156.78 

70. 13-143 .63 

66.87-162.63 

64.90-147 .90 

65.28-126.80 

72.00-125.27 

76.23-119.32 

78.68-103.53 

68. 78 ·81.25 

82.50 -62.33 

70.47 -68.62 

72.97 -84.53 

80.00 -85.93 

73.03 · 85.15 

74. 72 -94.95 

25248 I LI RNEY J 

25282 VANKAREN 

25399 MYS UELEN 

25400 ZYRIANKA 

25428 CHERBAROVO 

70026 BARROW, AK 

70086 BARTER IS., AK 

70133 KOTZEBUE, AK 

70192 145UNIVERSITY EXP STA 

71043 NORMAN ~ELLS, NT 

71051 SACHS HARBOUR, NT 

71072 MOULD BAY, NT 

71074 ISACHSEN, NT 

71081 HALL BEACH, NT 

71082 ALERT, NT 

71090 CLYDE, NT 

71914 NANISIVIK, NT 

71917 EUREKA, NT 

71918 ARCTIC BAY, NT 

71924 RESOLUTE BAY, NT 

71925 CAMBRIDGE BAY, NT 

71938 COPPERMINE, NT 

71957 INUVIK, NT 

71968 SHINGLE POINT, YT 

C7M 

TOTAL 

SOVIET 

SOVIET 

SOVIET 

SOVIET 

SOVIET 

ALASKA 

ALASKA 

ALASKA 

USA 

CANADA 

CANADA 

CANADA 

CANADA 

CANADA 

CANADA 

CANADA 

CANADA 

CANADA 

CANADA 

CANADA 

CANADA 69.10-105.13 

CANADA 

CANADA 

67.82-115.13 

68.30-133.48 

CANADA 68.93-137.23 

66.00 2.00 

2231 

am 

6 

18944 

10 

24628 

5356 

20461 

96 

2 

23793 

21946 

1478 

15175 

19425 

21842 

6272 

18090 

18478 

3 

73 

7373 

13294 

13838 

2n13 

24613 

4869 

2 

23631 

22302 

28243 

21518 

22020 

26745 

13867 

2 

28437 

5697 

29933 

13122 

******* ** 

******** 

• • 

•••••••••••••••••••••••••••••• 

* • 

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••••••••••••••••• 

•••••••••••••••••••••••••••••• 

************ 

• 

****************************** 

****************************** 

******** 

****************************** 

****************************** 

****************************** 

****** ********************* 

•••••• ******************** 

•••••••••••••••••••••••••••••• 

• 

******** 

****************** 

************************* 

****************************** 

*****************A********************** 

············~······················ •••••••••••••• 

* 

********************************* 

******************************** 

**************************************** 

******************************* 

******************************* 

•••••••••••••••••••••••••••••••••••••• 

********************* * 

* 

•••••••••••••••••••••••••••••••••••••••• 

• • ••••••• *** * 

**************************************** 

** * ****************** 

14132 *********************** 

19942 **************************** 

7056 

15521 

1,220, 713 

97 

*********** 

• • *************** 
archive); or (3) making their own determination of data 

quality. The data processing and error-checking procedures 

are described in detail in Serreze et al. [ 1991]. 

4. ACCESSING THE ARCHIVE 

The data base is currently archived on 9-track magnetic 

tape at the National Snow and Ice Data Center at the 

University of Colorado in Boulder. Efforts to transfer the 

archive to CD-ROM media are in progress. Requests for the 

data base may be directed to the Data Center in Boulder. 

5. REFERENCE 

Serreze, M.C., J.D. Kahl, and S. Shiotani, The historical Arctic 

rawinsonde archive document.ation manual. In preparation (preprint 

available from J. Kahl, Dept. of Geosciences, Uni e~ity of 

Wisconsin-Milwaukee, P.O. Box 413, Milwaukee WI 53201), 1991. 

98 
Trajectory Forecasting for Misers Gold 

JONATHAN D. KAHL 

University of Wisconsin-Milwaukee, Department ofGeosciences, Milwaukee, Wisconsin 53201 

RUSSELL C. SCHNELL AND PATRICK J. SHERlDAN 

CIRES, University of Colorado, Boulder, Colorado 80309 

1. 1NTRODUC110N 

Here we describe an experiment where a real-time 

trajectory forecast model was used to estimate the transport 

of debris associated with a large chemical explosion in the 

southwestern United States. The trajectory forecasts were 

used to vector sampling aircraft into a position favorable for 

intersecting the debris cloud. Full details of the experiment 

have been reported by Kahl et al. [1991). 

On June 1, 1989, the U.S. Defense Nuclear Agency 

conducted a high explosive test at White Sands Missile 

Range (WSMR) in southern New Mexico. The explosive 

charge consisted of 2.21 x 106 kg of ammonium nitrate fuel 

oil slurry that provided an airblast approximately equivalent 

to that which would be generated by a 4 kiloton nuclear 

device. The program, called "Misers Gold'', included 180 

experiments designed to collect basic explosive environmental data and to test the performance of various systems and 

structures in a simulated nuclear environment [Lutton, 1989). 

Trajectory forecasts, prepared in the field using a 

real-time trajectory forecast model, were used to track the 

position of the debris cloud after the winds had carried it 

beyond visual range. For the forecast trajectory model, the 

NOAA program for operational trajectories model [Heffter 

and Stunder, 1987) was used. The model uses archived wind 

data from the U.S. National Meteorological Center's Nested 

Grid Model (NGM). Forward or backward trajectories may 

be run in forecast mode using prognostic fields from the 

NMC forecast models, in diagnostic mode using observed 

data, or in a combined diagnostic/forecast mode. Both twoand three-dimensional trajectories are available at a number 

of vertical levels from 1000 mb to 100 mb. In this study 

only forward, quasi-two-dimensional (isobaric) trajectories 

were used. All trajectories were calcul ated at the 500-mb 

level. 

Beginning 39 hours before the blast, forward trajectories 

were initiated at the Misers Gold detonation site at WSMR. 

The forecast trajectories were programmed to start at 1500 

UT on June 1, 1989, to correspond as closely as possible to 

the planned blast time of 1500 UT (the actual blast occurred 

at 1530 UT). The trajectories were updated every 12 hours 

as new data from the NGM prognostic model became 

available. After the blast, trajectory forecasts originating at 

intermediate debris cloud positions were calculated to test 

the ability of the trajectory model to project the balloon and 

debris transport in real time using location updates. 

The accuracy of the trajectory forecasts is evaluated by 

comparing the forecast trajectories with diagnostic (afterblast) trajectories based on observed rather than forecast 

meteorological data and by comparing the projected cloud 

position with aircraft measurements of explosion debris. The 

diagnostic trajectories were calculated using the isobaric 

model described by Harr is [ 1982). 

2. RESULTS AND DISCUSSION 

Forecast Misers Gold debris trajectories are shown in 

Figure 1. The legends indicate the time, relative to the blast, 

that the forecasts were prepared. For example, the legend 

"T-39" refers to the trajectory calculated using NGM forecast 

winds based on meteorological observations at 0000 UT on 

May 31 , 1989, 39 hours before the planned blast time. 

Trajectory forecasts were made at T-39 hr, T-27 hr, T-15 hr 

and T-3 hr. Also shown is the post-blast diagnostic 

trajectory determined from the observed wind fields. 

Inspection of Figure 1 shows that the forecast trajectories 

predicted the diagnostic trajectory quite well. All trajectories clearly track i.n the correct northeasterly direction, 

although there are some differences in speed. Note that the 

forecasts improved as the trajectory initiation time approached the blast time. The position errors were small, 

however, all trajectories renect the southwesterly now at 500 

mb as depicted by weather charts (not shown). 

99 

MISERS GOLD 1 JUN 1989 1500 GMT 500 MB 

100 ' 

FORECAST AND DIAGNOSTIC TRAJECTORIES 

..... -..... ~ .... -· ; 

WSMR 

____ ;-·-···----·-= 

3 June 

0000 GMT 

·····-- .. ··. ·­ ·· ~ 

1---·-__ .... -·; 

_, 

~H'-~~~~~~~~~~~~~~~~'~ .. ~;,· 

Forecast 

Trajectories: 

A 

T-39 HR 

8 

T-27 HR 

c 

T-15 HR 

D 

T·J HR 

Diagnostic 

Traiectory: 

Fig. I. Forecast and diagnostic 500 mb trajectory positions. 

Legends indicate the time, relative to the planned blast time of 1500 

UT, June I, that the traje ctory forecasts were prepared. For 

example, the legend "T-39 hr" refers to the trajectory calculated 

using N:ws forecast winds based on then-current meteorological 

observations available 39 hours before the blast, on 0000 UT, May 

3 1, 1989. The symbols A, B, C, D and solid circles depict times as 

indicated by the large circles. 
The differences in the trajectories in Figure 1 are within 

the numerical uncertainty limits ascribed to trajectory models 

[Kahl and Samson, 1986]. These uncertainties are related to 

the limited spatial and temporal resolution of the 

meteorological data, the dynamics of the weather situation 

under study, and the performance of the meteorological 

forecast model. Despite these unavoidable uncertainties, the 

forecast trajectories compared well with the diagnostic 

trajectory, confirming the quality of the meteorological 

forecast data upon which the forecast trajectories are based. 

The "acid test" of any forecasting technique is a comparison of the forecast with independent observations of the 

variable or variables of interest. In the Misers Gold 

trajectory forecasting experiment, the necessary observations 

are downwind measurements of an indium tracer (ln2

0 3 ) that 

had been placed within the explosive charge. These 

measurements are available as instrumental neutron 

activation analyses of debris samples collected by the Los 

Alamos National Laboratory (LANL) aircraft chase team. 

Descriptions of the sampling and analytical techniques are 

given by Lutton [1989] and Mason et al. [1990]. Chemical 

analyses of the samples confirm that our forecasts of the 

debris cloud transport were correct. In this section we 

describe the trajectory forecasts used to vector the aircraft 

into a proper sampling position. 

During the Misers Gold experiment we were asked to 

vector the LANL aircraft to a position favorable for 

intercepting the debris cloud at the 500 mb level. At 2227 

UT on June 1, a request was made for a June 2, 1700 UT 

sampling location, which would be 26.5 hours downwind of 

the blast at WSMR. We therefore initiated a trajectory 

forecast at the best visual estimate of the debris cloud 

position available to us at that time. 

The evaluation of this forecast is shown in Figure 2. The 

LANL aircraft sampling took place from 1530-1700 UT 

rather than being centered at 1700 UT as originally 

scheduled. The line labeled "F" is the real-time after-blast 

trajectory forecast discussed above; the line labeled "D" is a 

diagnostic trajectory computed later using observed data. 

The estimated sampling location given to the aircraft crew is 

indicated by "M". This location, judged to be along the most 

probable path of the debris c loud, was assumed to be slightly 

to the north of the forecast trajectory (line "F"). 

Significant concentrations of the indium tracer were found 

in short (-40 km) sampling traverses centered around point 

"M". Figure 2 shows that the after-blast trajectory (line "F") 

compared favorably with the diagnostic trajectory, especially 

considering the fact that the trajectory crossed a region with 

significant convective precipitation [Kahl el al., 1991]. While 

the forecast and diagnostic trajectories followed nearly 

identical paths, the forecast trajectory was somewhat slower. 

This difference proved fortunate, as the aircraft sampling was 

centered 1.25 hours earlier than the time corresponding to the 

trajectory position originally requested. Given the significant 

dispersion that would have occurred in the -24 hour transport 

to this point, however , it is likely that a portion of the cloud 

would have been intercepted at the same location had the 

sampling occurred at the originally-scheduled time. 

M:Aitcrafl Samphng Location 

Traiectorits •Moated at I Jun•. 2100 GMT 

visual clOud obstrvation: D-Ooagnosbe 

f-Forocast • .... #' - .. • .. ••' tt. ;-..:_ 

--' 

Fig. 2. Evaluation of the trajectory forecast used to vector the Los 

Alamos National Laboratory sampling aircraft to a cloud interception 

point at 1700 UT, June 2, 1989. The projected location for cloud 

sampling is indicated by "M"; the Misers Gold debris cloud was 

indeed found there. Line "F" is the after-blast forecast of the debris 

cloud transport pathway. Line "D" is the diagnostic trajectory 

calculated later using observed meteorological data. 

10 "' l.llLES 

96•W 

Indium Concentrations (pg m"') 

T + 2430 - 2530 Hrs (a 1630 Z June 2) __ ..,,. 

---"'iici-----C oia9nostic J/ Tra1ectOtY 

~ ~ 

"° 

· 95•w 

Fig. 3. Isopleths of indium concentrations (pg/standard m3) measured 

by the LANL team from air samples collected between 24.5 and 25.5 

hours after the blast. Portions of the forecast and diagnostic 

trajectories from Figure 2 are also shown. 

Detailed results of the indium tracer measurements 

obtained by the LANL group [Mason et al., 1990] are shown 

in Figure 3. The measurements correspond to aircraft 

sampling in the viciniry of point "M" in Figure 2. The pP.ak 

concentrations of indium, 450 pg/standard m3, were observed 

only 20 km south-southwest of point M between 24.5 and 

25.5 hours after the blast. The presence of a distinct 

maximum in indium concentration close to the projected 

cloud center gives us reason to believe that the trajectory 

forecast did in fact direct the aircraft crew to near the center 

of the debris cloud at the 500 mb level. 

100 
3. CONCLUSIONS 

In this case a trajectory forecast model proved to be an 

accurate and inexpensive means of estimating atmospheric 

debris transport in an operational setting. The results 

summarized above lead us to conclude that forecast trajectories are valuable tools for vectoring sampling aircraft in 

atmospheric dispersion experiments and operations. Application of these models should prove useful in the future when 

forecasts of atmospheric transport are needed. 

4. R EFERE:-.ICES 

Harris, J.M., The GMCC atmospheric trajectory program, NOAA 

Tech. Memo. ERL ARL-116, Air Resources Laboratory, Silver 

Spring, Maryland, 30 pp., 1982. 

Heffler, J.L. and B.J.B. Stunder, Program for operational 

trajectories (POT), NOAA Tech. Memo. ERL ARL-157, Air 

Resources Laboratory, Silver Spring, Maryland, 12 pp., 1987. 

Kahl, J.D., and P.J. Samson, Uncertainty in trajectory calculations 

due to low resolution meteorological data, J. Climate Appl. 

Meteoro/., 25, 1816- 1831, 1986. 

Kahl, J.D., R.C. Schnell, P.J. Sheridan, B.D. Zak, 11.W. Church, 

A.S. Mason, J.L. Heffler, and J.M. Harris, Predicting atmospheric debris transport in real-time using a trajectory forecast 

model, Atmos. Environ., 25A, 1705-1713, 1991. 

Lutton, T., Misers Gold program document, Report POR 7350, 

Defense Nuclear Agency, Wa shington, DC, 284 pp., 1989. 

Mason, A.S., D.L. Finnegan, G.K. Bayhurst, R. Raymond, Jr., 

R.C. Hagan, G. Luedemann, K.H. Wohletz, Dust collection and 

cloud characterization, Misers Gold Symposium, Defense 

:-.luclear Agency, Kirtland Air Force Base, New Mexico, in 

press, 1990. 

101 
Trace Gases Over Hawaii: Concentrations, Trends, and Vertical Gradients 

M .A .K. KHALIL AND R.A. R ASMUSSEN 

Global Change Research Centu, Oregon Graduate lnstituJe, Beaverton, Oregon 97006 

1. INTRODUCTION 

For more than 10 years we have taken global measurements of trace gases at seven sites spanning latitudes from 

the Arctic to the South Pole. These sites are Point Barrow, 

Alaska; Cape Meares, Oregon; Cape Kumukahi and Mauna 

Loa, Hawaii; Cape Matatula, Samoa; Cape Grim, Tasmania; 

and the South Pole. Over the years this experiment has 

established the global trends of CH4, CO, N20 , H2 and 

F-113. The experiment has included the gases that are 

expected to be most significant in causing global environmental changes either by the greenhouse effect or by 

depleting t11e stratospheric ozone layer (CH4, N20, CC13F, 

CC1

2F2, CO). Also included are baseline studies of gases 

that may contribute to global changes in lesser amounts 

(F-22, F-113, CH3CC1 3, CC14 , H2 , and the nonrnethane 

hydrocarbons). The experiment at Hawaii is unique in that 

we have two sampling locations-one at sea level (Cape 

Kumukahi) and the other at 3.4 km above sea level (MLO). 

While the trends of trace gases at these sites are about the 

same, the average concentrations of most trace gases at Cape 

Kumukahi are gener ally significantly higher that at MLO 

[Rasmussen and Khalil, 1981; Steele el al., 1987]. Here we 

report the results obtained at the Hawaiian sites over the past 

decade. 

2. CONCENTRATIONS OF TRACE GASES 

Samples were taken in specially prepared stainless-steel 

fl asks, in triplicate, every week at the two sites starting in 

1980 [Rasmussen and Khalil, 1981). The flasks were sent to 

our laboratory where several gas chromatographs were used 

to measure the concentrations of trace gases. The results are 

summarized in Table 1 as annual average concentrations of 

12 trace gases. 

We first calculated the concentrations of trace gases 

during each montll, then took seasonal averages. For each 

year, the average of the seasonal concentrations is the annual 

average concentration. In some years we did not have data 

for all seasons. In such cases irnerpolated estimates were 

used to fill the gaps. We described tlle concentration as: 

C(season) = C0 + bt +Seasonal Cycle (1) 

where "Seasonal Cycle" is the average seasonal adjustment 

based on all the years of data [see: Khalil and Rasmussen, 

1990). C is the concentration at time t, C0 is the concentration in tlle base year, b is the rate of increase, and t is time. 

When there were no data in a given season, Eq. (1) was used 

to interpolate to obtain an unbiased annual average witll all 

four seasons represented. When data were missing for two 

or more seasons, tlle annual average was not computed. The 

periods when reliable annual averages could not be calculated are indicated by"--" in Table 1. 

The data in Table 1 show two features: first, there are 

significant increasing trends for most gases produced or 

affected by human activities; second, there is a difference of 

concentrations between Cape Kumukahi and MLO. 

3. TRENDS 

For tlle anthropogenic CFCs, CH4 , and some otller trace 

gases affected by human activities, tlle trends are the most 

apparent component of tlle time series. Using the seasonal 

concentrations of tlle trace gases, we estimated the trend by 

two different models: 

c =co+ bt (2) 

C = C0 exp(Pt) (3) 

where P is tlle rate of exponential increase. The results are 

reported in Table 2. The value of C0 is reported only from 

Eq. (2) since the two methods gave very similar results. 

Trends estimated according to Eq. (3) are not affected by 

errors in absolute calibration of concentrations. Moreover, 

Eq. (3) provides a uniform comparison of the trends of 

various trace gases that differ in absolute concentrations over 

many orders of magnitude. On the other hand, trace gases 

that are at very low concentrations can appear to increase 

extremely rapidly when Eq. (3) is applied. This is because 

the base concentrations are so low. Therefore, an evaluation 

of increases according to Eq. (2) is needed to provide a 

balanced view of the trends. The results are plotted in 

Figure 1. In tlle top panel we plot the percent-per-year 

increases sorted by highest to lowest values according to Eq. 

(3). F-113, F-22, and otller CFCs are increasing at faster 

percent-per-year rates tllan CH4, H2 , N20, and CO. In the 

lower panel the results from Eq. (2) are plotted to show that 

CH4, H2, N2

0, and CO are increasing faster in terms of 

number of molecules per year in the atmospheric compared 

to tlle fluorocarbons. 

4. VERTICAL GRADIENTS 

We estimated the difference of concentrations of trace 

gases at sea level (Cape Kumukahi) and above the boundary 

layer (MLO) based on the measurements taken since 1980. 

The results are shown in Table 3. The differences are 

generally lower tllan found in our previous evaluat ion 

[Rasmussen and Khalil, 1981 ). The earlier estimates were 

based on very few months of data, which did not reflect the 

long-term differences of concentrations. On the other hand, 

in tlle present evaluations, outliers have not been evaluated 

102 
TABLE 1. Annual Average Concentrations of Trace Gases in Hawaii 

H2 co CH4 N20 F- 12 F-1 1 F-113 CHC13 CH3CC13 CC14 F-22 CH3Cl 

ppbv ppbv ppbv ppbv pptv pptv pptv pptv pptv pptv pptv pptv 

Cape Kumukahi, Hawaii 

1980 87 1583 304 299 175 110 118 58 654 

1981 81 1589 304 312 184 117 119 64 642 

1982 9 1 1612 305 328 193 125 121 70 656 

1983 

1984 

1985 490 89 1668 306 376 22 1 32 17 143 126 88 615 

1986 489 84 1676 308 398 231 35 15 149 127 95 601 

1987 493 84 1698 310 417 245 39 15 160 133 103 586 

Mauna Loa, Hawaii 

1980 75 1565 303 291 172 105 113 55 637 

1981 72 1573 305 309 184 111 116 61 623 

1982 77 1601 305 325 191 119 119 69 644 

1983 80 1627 306 343 202 25 123 120 75 669 

1984 73 1636 307 359 209 27 128 124 80 646 

1985 488 81 1652 308 376 220 3 1 15 136 125 87 636 

1986 508 78 1665 310 396 230 34 13 140 127 93 635 

1987 523 75 1686 311 415 243 38 16 151 134 101 661 

TABLE 2. Trends of Trace Gases in Hawaii 

H2 co CH4 N20 F- 12 F-11 F- 113 CHC13 CH3CC13 CC14 F-22 CH3Cl 

Cape Kumukahi 

a 482 85 1575 333 3 11 181 13 27 135 146 56 664 

n 6 15 17 17 17 17 20 8 23 23 21 22 

b/YR 1.4 0.3 17.5 0.8 16.8 9.7 3.3 - 1.8 6.8 1.9 6.2 -9.9 

b%/yr 0.8 0.2 1.0 0.2 4.8 4.7 9.5 - 13.5 5.1 1.5 7.9 - 1.6 

MaunaLoa 

a 401 76 1566 333 306 179 16 16 128 140 53 638 

n 5 24 24 24 24 24 12 8 27 27 27 27 

b/yr 17.4 0.3 17.2 1.0 17.4 9.8 2.8 --0. 1 6.3 2.7 6.5 1.9 

B%/yr 4.2 0.4 I.I 0.3 4.9 4.7 I I.I 1.9 4.8 2. 1 8.2 0.3 

C0 = concentration in base year, n = number of months of data, b = rate of increase using a linear trend mode~ = rate of increase in percent 

per year using an eitponential trend model. 

TABLE 3. Average Difference of Concentrations of Trace Gases: Cape Kumukahi and Mauna Loa 

112 co CH4 N20 F-12 F-11 F- 113 CHC13 CH3CC1 3 CC 14 F-22 CH3Ci 

<d> - 15.6 8.1 12.9 -0.3 2.7 2.3 I.I 1.8 7.6 1.3 2.6 -18.6 

n 30 50 5 1 50 51 51 30 30 51 51 51 48 

90%cl 4.7 2.5 2.6 1.7 1.7 1.7 1.4 1.7 1.5 1.4 1.8 7.2 

<%d> -4.1 9.4 0.9 -0.4 0.6 0.6 0.7 5.0 5.4 0.7 2.2 -2.9 

t (yrs) 2 0.2 10 100 75 50 11 0 0.5 6 50 20 2 

<d> (and <'J'od>) = Estimates of average difference of concentrations (or percent difference of concentration) at MLO and Cape Kumukahi, 

90%cl = 90% confidence limits of <d>, Tau= average lifetime of a trace gas. 

103 
~ 

! 

~ "' 

... 

a 

.. 

i= 

.-. 

0 

10 

,..J 

~ 

I 

~ 

u ....,, 

0 

\,) 

c: 

0 

.... 

0 

.... 

.... 

:a 

~ 

0.3 

0.1 10 100 

L ifetime (yrs) 

Fig. I. Difference of concentrations in and above the boundary 

layer at Hawaii as a function of average tropospheric lifetimes of 

the trace gases. 

11 

10 

~ 

i 

-:: 

. 

i= 4 

10 0 000 

100 0 0 

1000 

100 

10 

Pl I 3 Pll NCP Pl l Pl l CCl4 CH4 Hl NlO CO 

~ 

i( ~ 

CH4 Hl NlO CO P l l Pl I MCP Fll Pl 13 CCl 4 

Ou 

E::}) C.Xumukahl - Mnn• Loo 

Fig. 2. Trends of trace gases in Hawaii. Trends are shown both as 

percent-per-year increases and increases in pptv/yr. 

and such data may be contributing to the reduced average 

differences of concentration in and above the boundary layer. 

The differences of concentrations in and above the 

boundary layer are plotted in Figure 2 as a function of the 

average atmospheric lifetimes of the trace gases. There is an 

inverse relationship between lifetime and the difference of 

concentrations as may be expected from previous work 

including our past publications [Khalil and Rasmussen, 

1983; 1984; 1988). 

5. CONCLUSIONS 

We have reported the results of trace gas measurements at 

Cape Kumukahi and MLO in Hawaii taken since 1980. The 

difference of concentrations between the two sites is 

somewhat less than our previous estimates. While concentrations of most gases are higher at Cape Kumukahi 

compared to MLO, the patterns for H2, CH3Cl, and Np are 

reversed. It is possible that volcanic contributions affect the 

concentrations of these gases at MLO. 

Acknowledgments. Samples at MLO were collected and 

shipped to our laboratory by NOAA/CMDL. Support for this 

work was provided in part by Biospherics Research Corp. 

and the Andarz Co. 

REFERENCES 

Khalil, M.A.K., and R.A. Rasmussen, Gaseous tracers of arctic 

haze, Environ. Sci. & Tech. 17 , 157- 164, 1983. 

Khalil, M.A.K., and R.A. Rasmussen, Statistical analysis of trace 

gases in arctic haze. Geophys. Res. Lei/. 11 , 437-440, 1984. 

Khalil, M.A .K., and R.A. Rasmussen, Trace gases over the 

western Atlantic Ocean: Fluxes from the eastern United States 

and distributions in and above the planetary boundary layer, 

Global Biogeochemical Cycles 2, 63-71, 1988. 

Khalil, M.A.K., and R.A. Rasmussen, Atmospheric methane: 

Recent global trends, Environ. Sci. Tech., 24, 549-553, 1990. 

Rasmussen, R.A. and M.A.K. Khalil, Atmospheric halocarbons: 

Measurements and analyses of selected trace gases, Proceedings of the NATO Advanced Study Institute on Atmospheric 

Ozone: Its Variation and Human Influences, A.C. Aikin (Ed.), 

U.S. Depanment of Transportation, Washington, D.C., 

209-231, 1980. 

Rasmussen, R.A., and M.A.K. Khalil, Differences in the 

concentrations of trace gases in and above the tropical 

boundary layer, Pure and Applied Geophysics, 119, 990-997, 

1981. 

Steele, LP., P.J. Fraser, R.A. Rasmussen, M.A.K. Khalil, T.J. 

104 

Conway, A.J. Crawford, R.H. Gammon, K.A. Masarie, and 

K.W. Thoning, The global distribution of methane in the 

troposphere, J. Atmos. Chem. 5 , 125-171, 1987. 
Radioactivity in the Surface Air at BRW, MLO, SMO, and SPO 

RICHARD J. LARSE~ A~D COLL'-: G. SA:\TIERSO~ 

U.S. Department of Energy, Environmental Measurements Laboratory, New York, New York 10014-3621 

1. INTRODUCTION 

Air filter samples are routinely collected by CMDL 

personnel at BRW, MLO, SMO, and SPO for EML's Surface 

Air Sampling Program (SASP). The primary objective of 

this program is to study the temporal and spatial distribution 

of specific natural and anthropogenic radionuclides in the 

surface air. Of the radionuclides that arc analyzed by 

gamma-ray spectrometry, only the naturally occurring 

radioisotopes 7Be and 2lOPb are still readily measured in 

most of the filter samples. 7Be (half-life 53.2 days) is 

produced by cosmic-ray interactions in the upper troposphere 

and the stratosphere. 210Pb (half-life 22 years) is a decay 

product of 222Rn, which is a natural radioiso tope emitted 

from soils. Because of their distinctly different source 

regions, these radioisotopes serve as tracers for upper and 

lower tropospheric sources and transport processes. 

2. MATERIALS A1\'D METHODS 

Weekly air filter samples are continuously collected 

using Microdon filter material. The air samplers move 

-1700 m3 of air per day through a 20-cm diameter filter. 

The weekly filter samples collected at BRW and MLO are 

analyzed by gamma-ray spectrometry using a high-purity 

germanium (HPGc) detector with a 1.5-cm diameter well. 

For each site, one-half of each of the weekly filter samples 

arc added together to form a monthly composite san1plc. 

These composite samples arc compressed into a 45-cm3 

plastic planchet, and are routinely analyzed for several 

TABLE 1. Monthly Surface Air Concentrations of Radionuclidcs at BRW, MLO, SMO, and SPO During 1990 

Site Nuclide Jan. Feb. March April May June July Aug. Sep1. Oc1. Nov. Dec. 

BRW Gamma (cpm m·3) <0.01 <0.01 <0.01 <0.0 1 <0.0 1 <0.0 1 <0.01 <0.01 <0.01 <0.01 <0.01 <0.0 1 

MLO Gamma (cpm m·3) <0.01 <0.01 <0.01 <0.01 <0.0 1 <0.01 <0.01 <0.0 1 < 0.0 1 <0.01 <0.0 1 <0.01 

SMO Gamma (cpm m·3) <0.0 1 <0.01 <0.0 1 <0.0 1 <0.0 1 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.0 1 

SPO Gamma (cpm m·3) <0.01 <0.01 <0.0 1 • <0.0 1 <0.01 <0.01 <0.01 <0.01 <0.01 <0.0 1 <0.01 

BRW 7Be (mBq m·3) 1.4 1.7 1.7 1.6 1.0 0.8 0.4 0.6 0.7t 0.9 1.4 1.7 

MLO 7Be (mBq m·3) 5.2 5.8 6.6 6.4 5.6 6.9 4.8 5.3 3.8 6.1 2.2 4.4 

SMO 7Be (mBq m·3) 1.9 1.8 1.9 1.4 2.2 2.4 2.6 2.7 2.3 2.2 1.7 1.9 

SPO 7Be (mBq m·3) 2.8 <2.4 <2. 1 • J.Jt 2.2 1.9 I.I l.6t 3.5 3.4 4.1 

BRW 9szr (μBq m·3) <6.6 <3.3 <3.1 <2. 1 <4.0 <6.8 <6.0 <4.0 <16.2 <11.8 <5.9 <9.8 

MLO 9szr (μBq m·3) <10.0 <7.6 <5.2 <10.1 <8.8 <3.9 <7.9 <14.1 <17.3 <29.6 <39.8 <15.9 

SMO 9szr (μBq m·3) <5.0 <5.9 <7.2 <5.4 <5.0 <10.5 <7.8 <4.5 <11.3 <14.1 <28.9 <9.9 

SPO 9Szr (μBq m·3) <6.2 <200.0 <178.0 • <51.5 <52.7 <37.9 <17.6 <26.3 <13.4 <8.6 <35.7 

BRW 137Cs (μBq m·3) <1.6 <1.0 <0.9 <0.6 <0.8 <l.J <1.5 <1.3 <I.I < 1.0 <0.5 <I.I 

MLO t37Cs (μBq m·3) <2.8 <2.6 <1.8 <2.6 <2.4 <1.0 <3.2 <2.5 <1.2 <2.3 <3.7 <1.2 

SMO t37Cs (μBq m·3) <1.3 <1.3 <J.5 <1.5 <1.0 <2.8 <1.7 <1.3 <1.6 <2.4 <1.8 <0.8 

SPO t37Cs (μBq m·3) <1.2 <1.9 <i.7 • <I.I <1.7 <1.4 <1.2 <2. 1 <1.7 <1.3 <3.3 

BRW 144Ce (μBq m·

3) <6.5 <3.3 <3.3 <2.4 <3.2 <3.5 <5.7 <4.7 <4.7 <3.9 <1.8 <5.3 

MLO 144Ce (μBq m·3) <10.7 >9.5 >7.4 >11.7 >10.5 <4.0 <10.6 <12.4 <6.3 <12.5 <2 1.J <5.1 

SMO 144Ce (μBq m·

3) <4.5 <5.0 <6.5 <5.8 <4.4 <11.3 <6.5 <5.5 <7.2 <10.7 <9.3 <4.0 

SPO 144Ce (μBq m·3) <4.2 <15.l <14.0 • <6.1 <10.6 <6.6 <4.8 <8.1 <8.0 <5.0 <12.3 

BRW 210pb (mBq m·3) 0.86 1.04 1.00 0.54 0.22 0.08 0.06 0.09 0.09 0.27 0.61 0.81 

MLO 210pb (mBq m·

3) 0.19 0.27 0.38 0.48 0.39 0.55 0.33 0.26 0. 19 0.26 0.08t 0.18 

SMO 210pb (mBq m·3) 0.05 0.05 0.03 0.04 0.06 O.IOt O.O?t 0.09 0.08 O.IOt 0.05t 0.05 

SPO 210pb (mBq m·

3) 0.03 0.02t 0.02t • O.Olt 0.02t 0.02t O.Ol t 0.02t 0.04t 0.03t 0.04t 

•No data 

tUnccrtainty is between 50% and 100%; 

tUuncertainty is between 20% and 50%; uncertainty for all other conccn1ra1ions is <20%. 

105 
gamma-ray-emitting radionuclides using either HPGe n-type 

low-energy coaxial or Ge(Li) or HPGe p-type coaxial 

high-resolution germanium detectors. Detailed information 

on SASP is periodically published [Larsen and Sanderson, 

1990]. 

3. R ESULTS 

The results of the analyses of several radionuclides and 

the total gamma-ray activities for the monthly composite 

samples from filters collected at BRW, MLO, SMO, and 

SPO during 1990 are reported in Table 1. The total 

gamma-ray activities are reported in units of counts per 

minute (cpm) per standard cubic meter (15"C, 1 atm) of 

sampled air. The surface air concentrations of 7Be and 

210Pb are reported in millibecquerels (mBq) per standard 

cubic meter of air, and 9SZr, 137Cs, and 144Ce are reported in 

microbecquercls (μB q) per standard cubic meter of air. The 

concentrations are reported as corrected for radioactive 

decay to the midpoint of the month of collection. The 

results of the analyses on the weekly samples from BRW 

and MLO are being prepared for publication as an EML 

report. 

4. D ISCUSSION 

There were no armounced atmospheric nuclear weapons 

tests or other reported significant releases of radioactive 

materials into the atmosphere during 1990, and the concentrations of fission products such as 95Zr, 137Cs, and 144Ce were at 

or below the lower limits of detection for the analytical and 

sampling techniques that we currently use to measure them. 

The monthly mean concentrations of 7Be nd 210PB show a 

seasonal cycle at all CMDL sites. Feely et al. [1989] 

described the factors tlrnt cause seasonal variations in the 7Be 

concentration in the surface air. 

Acknowledgment. We wish to thank the NOAA/CMDL staff at 

BRW, MLO, SMO, and SPO for the collection of air filter samples 

for the SASP. 

5. R EFERENCES 

Feely, H.F., R.J. Larsen, and C.G. Sanderson, Factors that cause 

seasonal variation in beryllium-? concentrations in surface air. J. 

Environ. Radioacti11i1y, 9, 223-249, 1989. 

Larsen, R.J., and C.G. Sanderson, Annual report of the surface air 

sampling program, EML-524, 120 pp., U.S. Department of Energy 

Environmental Measurements Laboratory, New York, 1990. 

106 
Zonal Representativeness of Cape Grim C02 Measurements 

G. I. PEA&\1AN, D. J. BEARDSMORE, R. J. FRANCEY 

CS/RO, Division of Atmospheric Research, Victoria, Australia 3195 

1. INTRODUCTION 

It has long been recognized that annual average C02 

concentrations measured in air of marine origin at Cape 

Grim have registered lower concentrations than comparable 

measurements in the southern hemisphere [Tans et al., 

1990]. The reasons for this have not been fully understood, 

with initial investigations concentrating on standard 

intercalibration and data selection. Recently an intercalibration between the C02 programs at Amsterdam Island 

(French, 37 ' S, 77'E), Baring Head (New Zealand, 41 'S, 

170' E) and Cape Grim (Australian, 41 ' S, 150' E), revealed 

that the calibration scale applied to the Australian results was 

around 0.6 ppmv too low [Monfray et al., 1990]. 

The Australian scale is based on WMO secondary 

standard mixtures purchased from Scripps Institution of 

Oceanography and last calibrated in 1984. The lack of 

access to a primary standard calibration since 1984 meant 

that a drift in the Australian standard was not unanticipated. 

The purpose of this report is to establish (a) when the 

Australian standards began to deviate from the international 

scale, and (b) a history of the difference of Cape Grim C02 

values from comparable records at similar southern latitudes. 

Two flask records arc used to assist in the comparisons: 

one from Cape Grim but measured on the NOAA/CMDL 

scale and one from aircraft over southeast Australia 

(approximately 38' S, l45' E, 4 km altitude) on the Australian 

calibration scale. 

2. DATA RECORDS 

In an attempt to determine when the scale of the WMO 

secondary tanks held at CSIRO, Division of Atmospheric 

Research, commenced to drift with respect to the WMO 

Primary Standard, the differences between Cape Grim 

monthly means and those of other programs were computed. 

Details of data sets used for these comparisons arc: (a) Cape 

Grim (CSIRO, Australia) values as published to the end of 

1984 [Beardsmore and Pearman, 1987] and, from 1985-1989 

as provided for appropriate reports of the WMO Environmental Pollution Monitoring and Research Program. (b) 

Baring Head (DSIR, New Zealand) values to 1984 [Manning 

and Pohl, 1986] and provisional values 1985-1989 (personal 

communication, A. Gomez). (c) Amsterdam Island (CNRS, 

France) values from 1980-1988 [Gaudry, et al., 1991] and 

provisional data for 1989 (personal communication, M. 

Ramonct). (d) Southeastern Australia midtroposphere 

(CSIRO, Australia) values as published to the end of 1981 

[Pearman and Beardsmore, 1984] and the 1985-1989 CSIRO 

data currently being prepared for publication. 

Since 1984, NOAA/CMDL has collected and analyzed air 

samples in flasks from Cape Grim. As the Cape Grim in situ 

values at the time of sample collection are available, these 

data were also obtained from 1984-1990 (personal communication, T. Conway) to provide an additional comparison. 

3. lNTERCOMPARlSON OF DATA RECORDS 

Figure 1 plots 12-month running means at six monthly 

intervals, of the differences between the Cape Grim monthly 

means of baseline C02 and those from the other data sets. 

All three graphs show similar gross features until about 

1987 /1988 when the differences between Cape Grim and 

both Baring Head and Amsterdam Island continue to rise 

while Gape Grim minus southeastern Australia midtroposphere falls sharply. We assume that this was the time when 

the Australian standards started to diverge from the true 

WMO 1985 Calibration Scale. 

To pinpoint the start of drift more accurately, the monthly 

means of the differences between CMDL flasks and Cape 

Grim in situ (at the sampling time) were plotted (Figure 2). 

These data also show a d ivergence from about 1987. When a 

24-month running mean is added (solid line), the d ivergence 

is confirmed to begin at this time after a steady mean 

difference of 0.37 ppmv. In view of the large scatter in the 

data we have assigned January 1987 as the time of commencement of drift on the basis of visual inspection of 

Figure 2. 

··0··0·0· Am1terdem l 1land 

1. - 0- - c - 01tlng H•ad 

> 

E 12 

.e " 

.. 

" 1 0 c 

.. 

~ 0 08 

c 

.e 

~ 0.6 

c 

.. 

" c 

0 04 u 

... 

0 

u 02 I I 

l) 

76 78 80 8 2 86 88 90 

Year 

Fig. 1. Twelve month means (at six month intervals) of the 

monthly C02 concentration differences between Cape Grim and SE 

Australian midtroposphere (crosses), Baring Head (circ les) and 

Amsterdam Island (squares). 

107 
'.l:,J.• ; •;t ·· -~ 

•. ~ }. • ,:_Jo.,• ~ •1 '. r• 

·- - . . :/ - .....:. - - ___..!. ·- -.. -.....:..:;:. ~... •• 

:-:f..i' ~,:: 

. ~ ,~ .. 

Fig. 2. Monthly mean C02 concentration differences between 

CMDL flasks, and in situ measurements at the same time, from 

Cape Grim. The solid line is a 24-month running mean of the data 

points. The 1984-1986 mean and nominal "start-of-drift" are 

identified by dashed lines. 

Therefore, if we take the magnitude of the drift relative to 

the French/New Zealand scales lo be 0.63 ± 0.03 ppmv in 

August, 1990 [Mon/ray et al., 1990], assume that it is linear 

with time, and that it started in January 1987, a correction of 

0.013 ppmv/month can be computed. From the CMDL 

comparison alone, a smaller drift of 0.010 ppmv/month is 

indicated. A detailed intercomparison of CMDL and 

Australian scales would help to refine the actual correction. 

The resulting corrected differences between Cape Grim 

and both Baring Head and Amsterdam Island are included in 

Figure 1 without symbols. 

4. ll'frERANNUAL VARIATION IN THE 

CAPE GRIM "DEFICIT" 

The most striking feature of Figure 1 is the coherence in 

interannual variation of the differences of all three other 

stations from Cape Grim. There is a strong implication that 

the Cape Grim record is influenced by a surface sink which 

varies in intensity on interannual time scales. For the 

aircraft record (on the same calibration scale as Cape Grim 

and effectively representative of air vertically above Cape 

Grim, Beardsmore, unpublished data), the difference is a 

maximum of 1.4 ppmv in 1980/1981 (slightly preceding the 

1982-1983 Southern Oscillation Index) and a minimum of 

0.3 ppmv in 1984/1985. 

A possible controlling inf1uence on the interannual 

variability emerges from a preliminary analysis of wind 

speed and direction data taken from the Australian baseline 

series of publications. Figure 3 shows a history of the 

frequency of occurrence of winds recorded in the western 

and southwestern "baseline sector," also the annual average 

wind speeds in meters per second. A significant interannual 

variation in the frequency of occurrence of "baseline winds" 

is evident, with the same phasing as the variation in "C02 

difference from Cape Grim" in Figure 1. An independent 

confirmation of this behavior [Harris et al., 1988], identifies 

the number of days of zonal westerly winds over Tasmania 

from 1945 to 1985 using daily surface synoptic weather 

60 • 

50 • 

40 

30 

20 

10. 

0 . -·-·-·-·-·-·-·....__....·- -·-·-

"' ~ ;;;: 0 x; " ~ ~ ~~ "' "' .., ~ a; "" "' "' "' "' ~ ?' ?' "' J' tragt 

Fig. 3. Annual mean wind speed (bars, in meters per second) and 

frequency of occurrence of winds in the 180' -270' sector (line, in 

percent) at Cape Grim. 

charts. The number of days of westerlies peaks around 1980 

at 140 days per annum, decreasing to around 70 days per 

annum in 1985. 

Two possibilities are under investigation for explaining 

interannual variation in the vertical gradient over Cape Grim 

via changes in westerly wind frequency. One of these 

hypothesizes a variation in the occurrence of sea breezes, the 

second changes in the air-sea exchange rate. A further 

possible influence of interannual behavior in the Indian 

Ocean circulation is also being investigated. 

Acknowledgments: The provision of unpublished C02 data 

from the French, New Zealand, and NOAA programs is 

acknowledged in the text. Staff of Cape Grim, which is 

jointly operated by the Bureau of Meteorology and CSIRO, 

played an essential role in the collection of high precision 

records over many years. 

5. REFERENCES 

Tans, P.P., LY. Fung and T. Takahashi, Observational constraints 

on the global atmospheric carbon dioxide budget, Science, 247, 

1431-1438, 1990. 

Monfray, P., M. Ramone!, A. Gaudry, G. Pearman, D. Beardsmore, 

M. Manning and P. Pohl, An intercalibration of C02 measurements between France, Austra lia, and New Zealand, Report to 

the WMO Meeting of Experts on C02 measurements, Lake 

Arrowhead, October 1990. 

Beardsmore, D.J. and G.I. Pearman, Atmospheric carbon dioxide 

measurements in the Australian region: data from surface 

observatories, Tel/us, 398, 42-66, 1987. 

Manning, M.R. and K.P. Pohl, Atmospheric carbon dioxide 

monitoring in New Zealand, 1971-1985, Report No. INS-R-350, 

Institute of :-.luclear Sciences, DSIR, New Zealand, 1986. 

Gaudry, A, P. Monfray, G. Polian, G. Bonsang, B. Ardouin, A. Jegou 

and G. Lambert, Non-seasonal variations of atmospheric C02 

concentrations at Amsterdam Island, Tel/us, 438, 136-143, 1991. 

Pearman, G.I. and D.J. Beardsmore, Atmospheric carbon dioxide 

measurements in the Australian region: ten years of aircraft data, 

Tel/us, 368, 1-24, 1984. 

Harris, G.P., P. Davies, M. Nunez and G. Meyers, Interannual 

variability in climate and fisheries in Tasmania, Nature, 333, 

754-757, 1988. 

108 
Aerosol Constituents at American Samoa: May-June 1990 

DENNIS L. SAVOIE AND JOSEPH M. PROSPERO 

University of Miami, Rosenstiel School of Marine and Atmospheric Science, 

Miami, Florida 33149·1098 

RICHARD ARL'vlOTO AND ROBERT A. D UCE 

University of Rhode Island, Graduate School of Oceanography, Center for Atmospheric Chemistry Studies 

Graduate School of Oceanography, Narragansell, Rhode Island 02882-1197 

1. INTRODUCTION 

A major goal of our cooperative work at SMO is to define 

more rigorously the sources, atmospheric pathways, and 

fluxes of particulate nitrogen and sulfur species in the remote 

marine atmosphere. Toward this end, we continue to collect 

weekly bulk aerosol samples at SMO where past studies [e.g. 

Arimoto et al., 1987] indicate that the transport of soil 

material and pollutants from continental sources is extremely 

low. In addition, daily samples were collected throughout 

November 1989 and from May l 0 to June 11, 1990, in 

support of the First and Second Survey Flights of the NASA 

Global Backscatter Experiment (GLOBE). The objective of 

GLOBE is to assess the feasibility of a space-based lidar 

system that could provide vertical profiles of winds over a 

substantial portion of the earth. Our task in this endeavor 

was to place the period of the flights within a climatological 

framework by comparing the results obtained during the 

flight periods to those from our long-term record. Here we 

concentrate on the r esults from the May-June 1990 intensive; 

the results from the November 1989 intensive were presented 

by Savoie et al. (1990). 

As with our nomrnl weekly samples, the daily samples 

were collected from onshore winds by drawing air through 

20 x 25 cm Whatman 41 filters at a flow rate of l. l m3 min-'. 

Nitrate, sulfate, and MSA in aqueous extracts of the filters 

were determined by ion chromatography, ammonium by 

automated colorimetry, and sodium by flame atomic 

absorption at the University of Miami; aluminum 

concentrations were measured by neutron activation analysis 

at the University of Rhode Island. Mineral aerosol was 

estimated from aluminum, which constitutes about 8% of the 

mineral aerosol mass. Nss sulfate was estimated as total 

sulfate minus sodium times 0.2517, the sulfate to sodium 

mass ratio in seawater. 

2. MEAN CO~CENTRA TIONS 

Samples included in this study were collected from May 

10 through June 11, 1990. The wind was very favorable 

throughout this period, being in-sector almost 95% of the 

time. The minimum in-sector time for a given sample was 

64% from May 27 to 28. The nitrate, sulfate, sodium, and 

MSA concentrations in the samples were all well above their 

detection limits; concentrations on the filters were at least 10 

times higher than in the blanks and the net concentrations 

(total-blank) were always al least 50 times higher than the 

standard deviation of the blank. In contrast, the ammonium 

aluminum blanks accounted for a major fraction of the total 

concentrations of these species in most of the samples. 

Gross ammonium concentrations in the samples were usually 

only a factor of 2 higher than the blanks with most net 

concentrations only factors of 3-4 higher than the standard 

deviation of the blank. For aluminum, the gross sample 

concentrations were frequently within the range of the blanks 

and were never more than a factor of 2 higher than the 

average blank. Because the reported sample concentrations 

are based on the net sample concentration (gross minus 

average blank), calculated negative concentrations frequently 

result when the atmospheric concentrations are extremely 

low, as is the case for aluminum. Though the results clearly 

attest to the very low concentrations of ammonium and 

mineral dust at the site, the high relative errors for these 

constituents make it difficult to assess the real day-to-day 

variations in their concentrations. 

Four of the samples were collected over 2-day (as 

opposed to 1-day) periods. In calculating the statistical 

parameters for the data set, each day of these 2-day periods 

was assigned the same set of concentrations, i.e. the mean 

concentrations fo r the 2-day period. The statistics calculated 

on this basis are presented in Table 1 along with other 

comparative data. 

The mean nitrate concentration at SMO during May 10-

June 11, 1990 (MJ90), is only about 8% higher than the long 

term (1983-1990) May-June mean, but 17% lower than the 

TABLE l. Concentrations of Various Species in Atmospheric 

Particulates for Several Time Periods at SMO 

NOr- NSS so; MSA Mineral N114+ 

μg m·3 μg m·3 ng·3 ng m·3 ng m·3 

May-June 0.()C)5 0.465 30.8 14.3 16.9 

1990 ±0.017 ±0.085 ±6.2 ±7.0 ±4.4 

May-June 0.088 0.322 29.8 11.3 16.9 

1983-1990 ±0.012 ±0.040 ±5.7 ±4.6 ±4.4 

1983-1990 0.114 0.368 25.9 19. 16. 

(All) ±0.(X>? ±0.019 ±5. 1 ±3. ±4. 

Nov. 1989 0.178 0.368 17.7 21. 26. 

±0.039 ±0.064 ±2.8 ±17. ±6. 

The data in this table were compiled from Prospero and Savoie 

(1 989], Prospero ti al. (1 989], Saltzman et al. (1985, 1986] and Savoie 

et al. [1989a]. 

109 
overall 1983-1990 mean. Moreover, the MJ90 mean is 

nearly a factor of 2 lower than that during the first GLOBE 

flight, November 1989. These results are consistent with the 

Jong-term nitrate seasonal cycle at SMO [Savoie et al., 1989]. 

In contrast to nitrate, the mean nss sulfate concentration 

during MJ90 is substantially (44%) higher than the Jong-term 

May-June mean and about 25% higher than the overall 

1983-1990 mean. These results conflict with the long-term 

nss sulfate seasonal cycle that showed relatively lower 

concentrations during this part of the year. In fac t, the MJ90 

mean is comparable to the highest long term monthly mean 

which occurs in September. 

The mean MJ90 MSA concentration is nearly identical to 

the long-term May-June mean but about 20% higher than the 

overall 1983-1 990 mean. However, because of the sparsity 

of previous MSA measurements, these comparisons must be 

viewed with caution. Certainly the most dramatic difference 

is between the MJ90 intensive and that of November 1989 

with the former being about 75% higher. These results 

suggest the possibility of a strong seasonal cycle in MSA, in 

contrast to the rather constant concentrations reported by 

Saltzman et al. [1 986]. 

Despite the extremely low levels of mineral dust at SMO, 

the results obtained from the MJ90 samples are consistent 

with those that we have obtained in the past. Hence, our 

results continue to support the contention that American 

Samoa is minimally impacted by the transport of materials 

from continental regions. As with nitrate, the mean MJ90 

concentration is comparable to the long-term May-June mean 

and about 20% lower than the long-term overall mean. 

Previous measurements of ammonium at SMO have been 

very sparse. Consequently, comparisons with the long-term 

data sets are of questionable value. However, it is interesting to note that the mean ammonium concentration during 

the MJ90 intensive is aboul 35% lower than that during 

November 1989. This difference is comparable to that for 

nitrate but sharply contrasts with those for nss sulfate and 

MSA which are both much higher during MJ90. 

3. DAlL Y VARIATIONS AND SOURCES 

The concentrations of each of the constituents exhibited 

substantial day-to-day variations during the MJ90 intensive 

(Figure 1). Nitrate varied by a factor of 6, from 0.036 lo 

0.21 μg m·3 . Sodium ranged from 2.0 to 7 .9 μ g m·

3, a factor 

of about 4. The sulfur species varied by factors of about 7 to 

8: MSA from 8.7 to 66 ng m·3; and nss sulfate from 0. 112 to 

0.87 μg m·3• The variations in the concentrations of the 

sulfur species tend to track one another reasonably well with 

major peaks near the beginning and the end of the intensive. 

Nitrate, in contrast, exhibits a peak near mid-month with 

relatively low levels near the beginning of the period. The 

differences between the nitrate and sulfur species time series 

support the conclusion that a marine biogenic source is 

probably not the dominant source of nitrate at SMO [Savoie 

et al., 1989b]. Ammonium exhibits several peaks of which 

two appear to coincide with those of the sulfur species and 

one with that of n itrate and/or mineral dust. 

;) 70 

I so 

E 50 

40 

30 

20 

- 10 

E o~i....1'1Wl1..-~W1.1ia..11Wli i - 10 

-20~~ ................. ~.....-~ ....................................................... ......1 

12 15 111 21 4 27 30 

0.20 

fi' 

IE 0.15 

~ 0.1 0 

~ 0.05 

0.00 

f o.a 

E -3 o.s 

~ 0.4 :t: 

:I 

(/) 

~ 0.2 

z o.o 

fi' 50 

I 

E 40 

°' -S JO 

~ 20 

10 

olfilU~~mumw~-~ 

SO ~-""'~.._...,,_~_,,.:!.-""-~'--'"--"--"-.. 

;) 

I 50 

E 

c "' 40 ........ 

E 

:I 

c 

0 

E 

~ 

30 

20 

10 

12 15 1 a 21 24 21 JO 2 s a 

Fig. 1. Daily-average concentrations of chem ical species in 

atmospheric paniculatcs at S:v10 from May 10 to June 11, 1990. 

110 
70 •Samoo: Nov. 1989 

•Samoo: May-June 1990 / 

60 ISomoo: 1983-1984 0 ,.._ OF'annlng: 1981 -1 982 

I"") 50 v Rarotonga: Nov. 1989 

/ I 0 0 o/. 

E ,,. o~ 1 <> 

40 . ~ /. 

O'l <> • ~ o<> • 

c 30 . ~~ "--" ,f//IJ I •o 

<X'. ~ v I 

CJ) 20 • :::::? 

10 • • 

0-¥-~~~~~~~~~~~~-I 

0.0 0.2 0.4 0.6 0 .8 1.0 

NSS Sulfate (μg m-3) 

Fig. 2. Methanesulfonate (MSA) versus nss sulfate at SMO, 

Fanning Island, and Rarotonga for various time periods. 

In an evaluation of earlier data, Saltzman el al. [1985) 

reported a reasonably consistent MSA/nss so; = ratio (0.065 

± 0.005) at SMO and Fanning Isl and. In Figure 2, we update 

their original data set with the November 1989 and MJ90 

data from SMO and the November 1989 data from 

Rarotonga. With these additions, the pattern remains 

reasonably consistent, supporting the conclusion that the nss 

sulfate at these stations is derived predominantly from the 

oxidation of dimethyl sulfide. With the 121 samples, the 

geometric mean MSA/nss so; = ratio, 0.0614 ± 0.0037, is 

not significantly different from that obtained from the 

original 55. However, the ratio at SMO may vary 

significantly. The original 1983 and 1984 weekly samples 

yield a ratio of 0.0593 ± 0.0078, the November 1989 samples 

yield 0.0490 ± 0.0068, and the MJ90 samples yield 0.0655 

0.0055. Only the November 1989 result differs significantly 

from the overall mean. Additional investigations will be 

required to assess the possible reasons for this apparent 

difference. 

4. OTHER COMPARISONS 

We have also compared our nss sulfate data with the 

condensation nuclei (CN) and nephelometer data acquired 

during these intensive periods by the CMDL personnel. 

Although the CN concentrations and the aerosol scattering at 

500 nm are significantly correlated with the nss sulfate 

concentrations, there is considerable scatter in the 

relationship. We tentatively ascribe much of this scatter to 

variations in the size distribution of the nss sulfate particles, 

primarily as a function of relative humidity. However, other 

processes such as coagulation of particles and growth of 

particles from the absorption of reactive gases may also play 

important roles. 

Acknowledgments. We thank T. Snowdon, Huang F., Huang T., and 

M. Izaguirre (all of UM) and J.D. Cullen (URI) for their technical 

assistance. We also thank C. Farmer and E. Wilson-Godinet 

(NOAA/CMDL SMO) for maintaining and operating our sampling 

systems. We gratefully acknowledge the cooperation of B. Mendonca 

and NOAA/CMDL Boulder for allowing us to continue our program 

at SMO. This work was supported under NASA contracts NAGS-62 1 

and NAGS-84 1. 

5. R EFERENCES 

Arimoto, R., R.A. Duce, BJ. Ray, A.O. Hewitt, and J. Williams, 

Trace elements in the atmosphere of American Samoa: 

Concentrations and deposition to the tropical South Pacific, J . 

Geophys. Res., 92, 8465-8479, 1987. 

Prospero, J.M., and D. L. Savoie, Effect of continental sources on 

nitrate concentrations over the Pacific Ocean, Nature, 339, 

687-689, 1989. 

Prospero, J.M., M. Uematsu, and D.L. Savoie, Mineral aerosol 

transport to the Pacific Ocean, in Chemical Oceanography, JO, 

edited by J.p. Riley, R. Chester, and R.A. Duce pp. 188-218, 

Academic Press, London, 1989. 

Saltzman, E.S., D.L. Savoie, J.M. Prospero, and R.G. Zika, 

Atmospheric methanesulfonic acid and non-seasalt sulfate at 

Fanning and American Samoa, Geophys. Res. Lett., 12, 437-440, 

1985. 

Saltzman, E.S., D.L. Savoie, J.M. Prospero, and R.G. Zika, Methanesulfonic acid and non-seasalt sulfate in Pacific air: Regional and 

seasonal variations, J. Atmos. Chem., 4, 227-240, 1986. 

Savoie, D.l., M.M. Prospero, and E.S. Saltzman, Nitrate, non-seasalt 

sulfate, and methanesulfonate over the Pacific Ocean, in Chemical 

Oceanography, JO, edited by J.P. Riley, R. Chester, and R.A. 

Duce, pp. 2 19-250, Academic Press, London, 1989a. 

Savoie, D.L., J.M. Prospero, J.T. Merrill, and M. Uematsu, Nitrate in 

the atmospheric boundary layer of the tropical South Pacifi c: 

Implications regarding sources and transport, J. Atmos. Chem., 8, 

391-41 5, 1989b .. 

Savoie, D.L., J.M. Prospero, R. Arimoto, and R.A. Duce, Aerosol 

constituents at American Samoa: November 1989, in Climate 

Monitoring and Diagnostics Laboratory, No. 18, Summary Report 

1989, edited by W.D. Komhyr, pp. 123-124, NOAA, CMDL, 

Boulder, Colorado, 1990. 

111 
Analysis of MSA and nss so; at MLO 

B.B. SHURTLEFF, X.Y. CAI, AND W.H. ZOLLER 

University of\Vashington, Chemislry Department, Seattle, Washington 98195 

I. INTRODUCTION 

Tropospheric downslope air samples collected between 

January 1, 1990, through June 6, 1991, from the Mauna Loa 

Observatory (MLO) on the island of Hawaii were analyzed 

for non- seasalt sulfate (nss so; ) and methanesulfonic acid 

(MSA) using ion chromatography (IC). 

2. SAMPLIKG AND ANALYSIS 

Atmospheric samples have been continuously collected at 

MLO utilizing the selective sampling system installed in 

1979 [Parrington, 1983]. Originally used to collect either 

upslope or downslope aerosol samples, the system currently 

collects only downslope samples by measuring wind 

direction and speed, time, and condensation nuclei (CN) 

count for parameters on which to make a decision. Since 

1989 downslope filter packs have consisted of five filters in 

tandem; the first, a Teflon filter, collects particulate matter, 

and the four subsequent filters are 1LiOH treated filters 

which collect acidic gases. When the testing parameters did 

not satisfy downslope criteria (i.e. interim parameters), a 

single Nucleopore filter was used to sample. However, due 

to pump failure on November 1, 1990, interim samples are 

no longer collected and the previously described five-filter 

pack for downslope sampling remains as the only means of 

collection. Currently, filters are analyzed by two methods: 

(1) instrumental neutron activation analysis (INAA) 

measures particulate elements on the Teflon filters, and (2) 

IC measures particulate species, such as MSA, on the Teflon 

filters and acidic gases, such as S02, HCI, and HN03, 

collected on the 1LiOH treated filters, and measures the 

residual ions left in the filters (i.e. so;, CJ-, and NO))-

3. DISCUSSION AND RESULTS 

MSA is an oxidation product of dimethyl.sulfide (OMS) 

released by oceanic phytoplankton into the marine boundary 

layer; nss so; comes from two main sources: continents and 

marine biological activity. Because MLO is 3.4 km high and 

the downslope air originates from an altitude of about 4 km 

[Parrington et. al., 1984), low levels of MSA were expected 

from the samples. In fact, levels of MSA in the samples 

were found to be considerably less than marine boundary 

layer samples (see Table 1). However, nss so; levels at 

MLO were found to be relatively similar to levels found at 

marine boundary layer stations. For MLO, the mean nssso; 

concentration and the mean MSA concentration for the 

testing period are 314 ng/m3 at STP and 2.3 ng/m3 at STP, 

respectively (see Figures 1 and 2). Table 1 shows concentrations for MSA and nss so; from the free troposphere (MLO) 

and several Pacific marine boundary layer stations. The ratio 

of MSA/nss so; is also shown as a means of easy comparison (see Figure 3). Ratios for marine boundary layer data 

were calculated; they were not obtained from the actual 

reports or references. 

Obviously, the mean concentration of MSA at MLO is 

very low in comparison to the boundary layer samples. The 

low mean concentration is due to the observatory's high 

altitude and downslope sampling procedure. Originating 

from a marine source, high concentrations of MSA cannot 

easily reach the 3.4 km altitude of the MLO when downslope 

winds are blowing. As previously mentioned, the downslope 

wind originates from an altitude of about 4 km; therefore, the 

measured MSA is from the middle troposphere (i.e. MSA 

which has migrated into the troposphere from the marine 

boundary layer). 

TABLE 1. Mean concentrations of Methanesulfonic Acid (MSA) and Non-Seasalt Sulfate (nss S04) 

at Mauna Loa, Hawaii, and at Several Marine Boundary Locations in the Pacific Ocean. 

Sampling Mean nss so; Mean MSA MSA/nss so; 

Location Year(s) ng/m3 (STP) ng/m3 (STP) Ratio 

Midway 1983-1987 370-930 10-33 0.027-0.35 

MLO Jan. 1990-June 1991 314±231 2.3 ±1.9 0.009 

Fanning Island 1983-1987 600-740 34-60 0.057-0.081 

S.\10 1983-1987 360 26 0.72 

::>few Caledonia 1983-1987 280-490 8.5-30 0.03 -0.061 

:\orfolk Island 1983-1987 121-400 5-75 0.041-0.187 

.\1awson, Antarctica Feb. 1987-0ct. 1989 90 20 0.222 

112 
8 

...... 6 .., 

E 

Ob 

c 

< Vl 4 

::E 

2 

0 

573 593 613 633 653 

Week Number 

Fig. 1. Weekly methanesulfonic acid concentrations al MLO for 

January 1990 through June 1991. 

The mean concentration of nss so: in the samples is 

similar to the other testing locations. However, unlike MSA, 

transport from Asia is the major contributor of nssso: in the 

troposphere at MLO on an annual basis. 

0.04 

0.03 

0 

Vl 

"' "' c 0.02 

< U'l 

:E 

0.01 

0.00 

573 593 613 633 

Week Number 

Fig. 3. .\1ethanes ulfonic acid/non-seasalt sulfate ratio at .\1LO for 

January 1990 through June 1991. 

1000 

800 

...... 

.., 

..§. 600 00 

5 

0 

Vl 400 "' "' c 

200 

593 613 

Week Number 

633 

Fig. 2. Weekly non-sea salt sulfate concentrations at MLO for 

January 1990 through June 1991. 

The MSA and nss so: concentrations appear to follow a 

seasonal cycle. However, the data also contain very large 

random peaks. Although the peaks tend to obscure 

evidence of a seasonal cycle, they are very strong indicators of storm or strong wind activity mixing marine 

boundary layer aerosols into the troposphere near MLO. 

Acknowledgments. This work was supported in part by 

NSF Grant 62-6955. We would like to thank the NOAA/ 

CMDL staff at MLO for their collection the air filter 

samples. 

REFERENCES 

Parrington, J.R., The chemistry of background atmospheric 

particles collected al Mauna Loa Observatory, Hawaii, Ph.D. 

Thesis, Univ. of Maryland, 1983. 

Parrington, J.R., and W .II. Zoller, Diurnal and longer-term 

changes in the composition of atmospheric particles at Mauna 

Loa, Hawaii, J . Geophys. Res., 89, 2522-2534, 1984. 

Savoie, D.L., and J.M. Prospero, Compa rison of oceanic and 

continental sources of non-sea-salt sulfate over the Pacific 

Ocean, Nature, 339, 685-686, 1989. 

113 
Stable Lead Isotope Ratios at Barrow, Alaska 

W.T. STURGES AND R.C. SCHNELL 

Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, Colorado 80309-0449 

J.F. HOPPER AND L.A. BARRIE 

Atmospheric Environment Service, Downsview, Ontario MJH 5T4, Canada 

1. INTRODUCTION 

Measurement of stable lead isotope ratios in atmospheric 

particulate matter provides a means to trace the origins of 

pollutant aerosols where there are marked differences in the 

isotopic composition of regional sources [Sturges and 

Barrie, 1987). Earlier measurements in the Canadian Arctic 

[Sturges and Barrie, 1989a] showed evidence for a Soviet 

origin of the lead. More recent measurements in Scandinavia 

[Hopper et al., 1991) have better characterized the regional 

isotopic signatures in Europe and the Soviet Union, and have 

also shown that it is necessary to examine ratios of both 

Pb206/Pb207 and Pb208/Pb207 to properly discriminate regional 

sources. The latter isotope ratio was not measured in the 

Canadian Arctic study. We undertook sample collection at 

BRW, to both better characterize the origins of leaded 

aerosol in the Arctic, and also to compare with the isotopic 

composition measured at the Canadian Arctic sites, 

thousands of kilometers away. 

2. METHODS 

Atmospheric particulate matter was collected at BRW 

between March and April 1990. Samples were collected by 

filtration at about 100 dm3 min-1 through 90 mm diameter 

Whatman 41 filters over periods of between 1 and 6 days 

(typically 2). Field blanks were collected in the same way as 

samples, but with the pump turned on for just 5 seconds. 

Breakthrough was assessed by placing a second filter in the 

filter pack. Samples were shipped and stored in heat-sealed 

semiconductor-grade-cleaned polyethylene bags. The 

samples were dry-ashed and acid-extracted for analysis by 

inductively coupled plasma mass spectrometry (Sciex Elan) 

at the Ontario Ministry of the Environment, Laboratory 

Services in Rexdale, Ontario (procedures described in 

Sturges and Barrie, 1989b and Hopper et al., 1991). 

3. RESULTS 

Figure 1 shows the measured Pb206/Pb207 results plotted 

versus atmospheric lead concentration. Only those data 

passing a rigorous quality control procedure have been 

plotted. Most of the points are clustered closely together. 

The highest isotope ratio was associated with snowmobile 

activity in the immediate vicinity of the sampler and 

corresponds to the ratio expected from U.S. leaded gasoline 

combustion. A meteorological analysis ruled out the 

possibility of pollution from the town of Barrow having 

affected the results, but we cannot rule out the chance of 

contamination from unreported vehicular activity close to the 

l'-

0 

N 

........... 

co 

0 

N 

,.D 

0.. 

1. 21 ~--~---.--~--irr---"T"-----. 

1.20 

1.19 

1.18 

1.17 

1.18 

1.15 

.... ····· 

// 

..... ·· / 

........ ··· 

957. confidence 

Interval 

1. 14 '--'---'--'--__ _..._ __ __. ___ _,__ __ _, 

0 2 4 6 8 

-3 Pb IN AIR (ng m ) 

10 

Fig. I. Isotope ratio Pb206tpb207 as a function of lead-in-air 

concentration. The linear regression line was computed excluding 

the high lead concentration outlier. The dashed lines show the 95% 

confidence limits of the regression line. Error bars are I sigma 

analytical precisions. 

sampler, although the uniformity of the ratios and their 

mostly lower ratios argue against this. 

The results for both isotope ratios are summarized in 

Figure 2 and compared with other data. The BRW results 

are shown as crosses, where the limbs of the crosses 

represent analytical uncertainties. Some of the the data are 

co-located and therefore not visible. The open elipses 

encompass the 95% confidence limits of representative ore 

bodies in the region, and the shaded elipses represent the 

95% confidence limits of the regional isotope signatures 

determined by Hopper et al. [1991). The shaded horizontal 

band represents the mean and standard deviation of the 

Canadian Arctic samples from Sturges and Barrie [1989a]. 

The measured Pb206fPb207 ratios were almost all very close 

to those from the Canadian Arctic study confirmimg that, on 

the time scale of days, the entire arctic basin is affected by a 

relatively uniform and homogeneous polluted air mass. The 

crosses mostly fall close to the signatures for Eastern Europe 

and the East (essentially the northern and central Sov iet 

114 
1.20 

1.15 

Pb 206 

Pb 207 

I. I 0 

1.05 

1.00 

Canadian Arclic 

2.25 2.30 

+ 

Eastern Eu r ope _ 

USSR 

Northern Sabena 

Cent ral, Southern 

USSR 

Kola Peninaula 

2.35 2.40 2.4 5 2.50 

Pb 208 / 207 

Fig. 2. Pb206tpb207 versus Pb208/Pb207 for some representative lead ores (open ellipses), regional lead aerosol signatures dt:tt:nnint:<l by 

Hopper et al. [ 1991] (shaded ellipses), lhe mean and standard deviation of Pb206/Pb207 ratios measured al Alert and Mould Bay from lhe 

Canadian Arctic by Stwgu and Barrie [1989a] (thick horizontal line and shaded band respec1ively), and the resuhs from lhis s1udy al BRW 

(crosses, where lhe limbs represent I sigma analytical precisions). 

TABLE 1. Estimated Apportionment, From This Study, of Aerosol Lead at BRW to Eurasian Sources, 

Compared With Similar Apportionments of Elements in Arctic Aerosol From Other Published Studies 

Apportionment(%) 

Reference/Location Method Elemenl Easl* Wcs1em Europe North America 

This study Pb isotopes Pb 67 33 ? 

BRW 

MaenhauJ el al. [ 1989] Elemental ratios Pb 63 37 <<10 

Ny Alesund 

Lowenthal and Rahn [ 1985) Elemental ratios Trace elemenls 60-74 20-28 6-19 

BRW 

Alceredolu et al. [ 1991] Transport model Pb -66 -33 ? 

Arctic 

*East = USSR and E. Europe 

115 
Union). They arc similar to ratios in central/southern 

U.S.S.R., but unlike those in the huge northern metallurgical 

plants of northern Siberia and the Kola Peninsula. 

We performed an apportionment calculation using the 

Pb208fPb207 data. These were selected since the mean Eastern 

European and East regional signatures were very close, and 

we could justify taking a mean value as representative of an 

undiscriminated Soviet/Eastern Europe source. We assume 

that only two homogeneous source regions contributed to the 

BRW leaded aerosol: t.he Soviet/Eastern Europe source and 

Western Europe. We then used a linear interpolation 

between the two mean signatures as our end points to 

calculate a day-by-day contribution factor from the two 

sources, weighted according to atmospheric lead 

concentration. Summing over the study period yielded the 

results shown in Table 1. We estimated that 67% of the lead 

was derived from the Soviet Union and Eastern Europe, and 

33% from Western Europe. We found no evidence for a 

North American contribution (other t.han local vehicle 

contamination). These result.s are remarkably similar to 

those from other, quite different, analyses by other workers 

for BRW, Ny Alesund, and the Arctic in general, also shown 

in Table 1. 

Acknowledgments. WTS thanks the l\ational Research Council for 

support. RCS was supported by the Office of Naval Research and 

the National Science Foundation under grant DPP-8822467. Thanks 

are due to CMDL for permission to use BRW, and we thank the 

station staff, especially Tim Quakenbush who set up the sampler and 

collected many of the samples. We also acknowledge the expertise 

of Mark Powell of the Ontario Ministry of the Environment who 

developed the technique for sensitive multiple lead isotope analysis 

in atmospheric aerosols. 

4. REFERENCES 

Akeredolu, F.A., L.A. Barrie, M.P. Olson, K.K. Oikawa, and J.M. 

Pacyna, The flux of anthropogenic trace metals into the Arctic 

from the mid-latitudes in 1979/80, Atmos. Environ., in press, 1991. 

Hopper, J.F., H.B. Ross, W.T. Sturges, and L.A. Barrie, Regional 

source discrimination of atmospheric aerosols in Europe using 

the isotopic composition of lead, Tel/us, 438, 45-60, 1991. 

Lowenthal, D.H. and K.A. Rahn, Regional sources of pollution 

aerosol at Barrow, Alaska, during winter 1979-1980 as deduced 

from elemental tracers, Atmos. Environ, 19, 2011-2024, 1985. 

Maenhaut, W., P. Camille, J.M. Pacyna, and V. Vitals, Trace 

element composition and origin of the aerosol in the Norwegian 

Arctic, Atmos. Environ., 23, 2551 -2569, 1989. 

Sturges, W .T. and L.A. Barrie, Stable lead isotope ratios in Arctic 

aerosols: evidence for the origin of arctic air pollution, Atmos. 

Environ., 23, 2513-2519, 1989a. 

Sturges, W.T. and L.A. Barrie, The use of stable lead 206/207 

isotope ratios and elemental composition to discriminate the 

origins of lead in aerosols in Eastern Canada, Atmos. Environ., 

23, 1645-1657, 1989b. 

Sturges, W.T. and L.A. Barrie, Lead 206/207 isotope ratios in the 

atmosphere of North America: tracers of American and Canadian 

emissions, Nature, 329, 144-146, 1987. 

116 
Atmospheric Bromine Measurements at Barrow, Alaska, Using a 

Sequential Filter Pack and Carbon Tube Sampler 

W.T. STURGES, R. C. SCl-Il\ELL, AND G. S. D UTTON 

Cooperative /nstitUlefor Research in Environmental Sciences, University of Colorado, Boulder, Colorado 80309 

S. R. GARCIA 

Los Alamos National Laboratory, Los Alamos, New Mexico 87545 

J. A. LIND 

National Center for Atmospheric Research, Boulder, Colorado 80307 

1. INTRODUCTION 

Bromine (Br) is of interest in the arctic atmosphere 

because of the now well-known spring "pulse" of particulate 

Br that has been observed at widely separated sites throughout the Arctic [Sturges and Barrie, 1988; Oltmans et al., 

1989). The pulse lasts for 2 to 3 months, during which time 

Br concentrations reach levels that are hundreds of times 

greater than summer and early winter values. The start of 

the peak is timed to the first appearance of sunlight at the 

particular site, suggesting a link to photochemistry. High 

concentrations of CHBr3, and other brominated organic 

gases, have been observed in late winter and early spring 

[Cicerone el al., 1988] and may be the source of the 

particulate Br. A strong anticorrelation between particulate 

Br and ozone has also been observed during the arctic spring. 

Barrie et al. [1988) conjectured that the ozone was being 

removed by the photochemical formation of Br atoms from 

CHBr3, although others have suggested that inorganic Br 

gases such as nitryl bromide may be important [FinlaysonPitts et al., 1990). 

The origin of CHBr3 in the Arctic has been something of a 

mystery, but recently we have measured emissions of CHBr3 

and other volatile organic Br species from both Antarctica 

and Arctic ice algae [Sturges et al., 1991b]. as well as high 

fluxes of CHBr3 out of leads and holes drilled in the ice 

(Sturges and Cota, unpublished data). Ice algae have been 

found on the underside of virtually all annual ice in the polar 

regions, constituting an enormous, and largely overlooked, 

amount of primary productivity. 

It is desirable to examine the speciation of Br between 

particulate and gaseous phases on a diurnal basis to further 

our understanding of the likely mechanisms involved in the 

Br pulse phenomenon. There is only one record, that of Berg 

et al. (1983), of an attempt to measure a complete 

breakdown of Br between organic, inorganic, and particulate 

phases. Unfortunately, results from just four samples were 

reported, and no attempt was made to examine diurnal 

variations. Furthermore, due to collection efficiency 

problems, they did not differentiate organic from inorganic 

gaseous Br. 

We have been fortunate to obtain the original sampling 

equipment of Berg et al. (1983). which we have modified for 

higher sampling rates. We have extended the data set at the 

same san1pling site (Barrow, Alaska), examined day/night 

differences, measured inorganic gaseous Br, and also 

measured organic gaseous chlorine. 

2. METHODS 

A filter pack arrangement was used to separate and collect 

the different phases of Br at BRW (see Sturges et al. [199la) 

for details). The Teflon filter pack contained a Teflon filter 

to collect particulate matter, followed by two absorbent 

filters in series to collect inorganic gaseous Br. These filters 

were either cellulose impregnated with potassium hydroxide 

(KOH) or pure Nylon 66. Following the filters were two (or 

three) tubes containing activated coconut charcoal, to collect 

organic Br gases. Using paired filters and tubes in series 

allowed us to measure, and correct for, collection efficiency. 

The charcoal was highly cleaned and vacuum fired using the 

procedure of Berg et al. (1983]; the process takes about 3 

months. 

The filters were extracted in ultra-pure water and analyzed 

at NCAR by ion chromatography (IC). Bromide, nitrate, and 

sulfate ions were measured. Chloride blank levels were too 

high for Cl measurements to be reported. The charcoal was 

analyzed non.destructively by neutron activation analysis 

(NAA) at Los Alamos National Laboratory (details in Berg 

et al. (1983)). 

3. RESULTS 

The carbon tube analyses of Br were most encouraging. 

Field blanks were below detection limit, and all samples 

were at least three times the detection limit. Collection 

efficiency was greater than 88% for all samples (mean of 

96%), even for sample volumes of up to 55 m3. This is 

remarkable considering that only 1.5 g of charcoal was used. 

Chlorine blanks were measurable, but all of the samples 

exceeded the blank by more than three standard deviations. 

Iodine could not be detected at more than one standard 

deviation above the blank. 

A summary of all the Br data is shown in Figure 1. It is 

clear from this figure that inorganic gaseous Br was an 

almost negligible component of total Br. Particulate and 

organic gaseous Br contributed variable, but roughly similar 

amounts of Br. We arc still in the process of fully examining 

our results, but some p•eliminary observations may be made 

as follows. 

117 
2 

91 

Day of Year (1990) 

Fig. 1. Summary of 13r measurements from the spring 1990 study 

period. 

In Figure 2a the particulate Br results are shown. Night 

and day samples are identified. It should be noted that the 

terms "night" and "day" as used here are somewhat misleading. The day samples were taken during the working day, 

i.e. about 0900 to 1700 LST. The night sample covers the 

remaining period, and incorporates several hours of full sun 

and twilight. Diurnal differences will consequently be 

somewhat muted in this record. The few multi-day samples 

at the end of the experiment have not been included in this 

plot. 

There appeared to be a tendency towards higher particulate concentrations during the day in agreement with the 

hypothesis of a link to photochemistry. In the next panel 

down (Figure 2b), organic gaseous Br shows some evidence 

for higher nighttime concentrations. Combining the two into 

a ratio in panel c indicates a diurnal variation in particulate 

to organic Br, with lower values at night. This again 

suggests photochemical loss of organic Br and formation of 

particulate Br. 

It was unfortunate that during the field experiment there 

was little deviation in ozone concentrations compared to 

those observed during the following weeks. There was only 

one distinct ozone destruction "episode" towards the end of 

the period (Figure 2d). Nevertheless, it is notable that this 

episode coincided exactly with the large peak in the 

particulate to organic Br ratio (panel c), suggesting some 

influence of Br chemistry on ozone concentrations. 

Figure 3 shows a plot of organic Br against particulate Br 

for day and night samples. This also illustrates the apparent 

inverse relationship between the two Br phases. The 

correlation coefficient r2 was CHBr3 -0.227 for all of the 

points, but increased to - 0.667 when the two low concentration outliers were removed. The regression line in the figure 

is for the latter correlation calculation. Surprisingly, the 

relationship appeared to hold even for the night samples. It 

should be remembered, however, that the night sample 

periods did include a significant amount of daylight. 

45 

""""" 40 (a) Particulate Br 

I') J5 ( 0 E J O 

........ 25 

en 20 H c t5 ........ 

..... to 

CD 5 

0 

160 

(b) Organic Br Gas 

""""" 140 I') H H ( 120 

E too ........ 

en 80 H 

c 

........ 60 

..... 40 CD 

20 

t.8 

t.5 (c) Ratio Particulate Br 

1.4 to Organic Br gas 

0 t. 2 

..... 1.0 

0 O.B 0 0:: 0.5 

0.4 

0.2 

0.0 

40 

""""" ..... J5 0 

.L:I JO c 

........ 25 Cl) 

c 20 0 

N t5 

0 

to 

85 88 90 92 94 911 

Day of Year ( 1990) 

Fig. 2 . Diurnal measurements of (a) particulate Br, (b) organic 

gaseous Br, (c) the ratio of partic ulate to organic gaseous Br, and 

(d) mean hourly ozone concenlrations averaged over the corresponding Br sampling interval. N = night sample , D = day 

sample, ND = 24-hour sample. 

140 

N 

N = night 

120 N D = day 

M" ' ' ' 

i100 

', ' ' N 

' ' D ' ', ID "N-, I ' ' ..... D ' ..... D 

<!) ' ' N 0 ' ' ' i D ' ' ' ' ' 0 N 0 N ' 1'1 , ,,D 

0 5 10 15 20 25 3J 35 40 45 

Particulate Br (ng/m'3) 

Fig. 3. Plot of organic gaseous Br against particulate Br for diurnal 

sample s. The regression line was calculated excluding the two 

outlying points with low organic gaseous Br concentrations. 

118 
250 

M' 

~ c:n1~ ~ .s 

100 

50 

PIO Pl PS P5 

Sample 

P3 

~ 

~ 

Fig. 4. Ratio of organic gaseous Br to organic gaseous Cl multipied 

by 1000 for diurnal samples. 

Organic Br and Cl were well correlated with an r2 of 0.67. 

It seems probable that both have some similar sources from 

Arctic marine biological activity. The non-zero Cl intercept 

(825 ± 453 ng m·3 or 522 ± 286 ppt Cl) may be at least partly 

due to pollutant Cl-containing gases. 

We expect to see some diurnal variation in the ratio of 

organic Br to Cl if they have similar source strengths and if 

we are correct in believing that Br gases are photolyzed in 

the lower troposphere, while most organic Cl gases are not, 

or to a much lesser degree. The ratios plotted in Figure 4 do 

appear to at least weakly support this hypothesis; in all cases 

there was a lower daytime ratio following the nighttime 

value. 

The final evidence for the importance of photochemistry 

comes from an experiment conducted at BRW where 

nighllime air was drawn through two glass chambers. One 

was kept dark as a control, and the other was illuminated 

with long-wave ultraviolet fluorescent lights. Filter packs 

were used to collect the effluent from the tubes (details in 

Sturges et al. [1991a]). Figure 5 shows that inorganic Br 

was destroyed in the illuminated chamber in every experiment. Using the same equipment we were able to demonstrate loss of ozone in ambient nighttime air from 20 ppb to 

zero in the illuminated chamber during 30 min stop flow. In 

1989, using similar equipment, we measured an irradiation 

time-dependent increase in particulate Br in the lit chamber 

[Sturges el al., 1991a]. Regrettably, we were not able to 

make reliable measurements of particulate Br in the latest 

experiment, due to the small sample size. 

The main conclusion of this study is that the results point to 

the existence of a rapid photolysis of organic Br gases in the 

arctic spring, resulting in the formation of particulate Br, and 

possibly accounting for the Br pulse phenomenon. There was 

also some supporting evidence for a link to surface ozone loss. 

We hope that further examination of the data, and integration 

with other chemical and meteorological data, including 

specific organic Br compounds measured by absorption tube 

N 

88 90 92 96 

Day of YeaJ (1990) 

Fig. 5. Results from irradiation of nighttime air at Barrow with long 

wave ultraviolet light Oight shaded bars) compared with a dark control 

chamber (dark shaded bars). 

collection and gas chromatography, will shed further light on 

arctic Br and ozone chemistry. 

Acknowledgments. WTS was supported by the National Research 

Council of the National Academy of Sciences. RCS was supported 

by the Office of Naval Research and the National Science 

Foundation under grant DPP-8822467. GSD was supported by 

undergraduate research grants from the Colorado Commission for 

Higher Education, and the Undergraduate Research Opportunities 

Program of the University of Colorado. We thank Paul Sperry of 

NCAR for generously donating the NCAR sampling system. We are 

also inJcbtcJ to CMDL for access to the BRW station and data, and 

to the station staff for their invaluable help. 

4. REFERENCES 

Barrie, L.A., J.W. Bottenheim, R.C. Schnell, PJ. Crutzcn, and R.A. 

Rasmussen, Ozone destruction and photochemical reactions at polar 

sunrise in the lower arctic atmosphere, Nature, 334, 138-141 , 1988. 

Berg, W.W., P.O. Sperry, K.A. Rahn, and E.S. Gladney, Atmospheric 

bromine in the Arctic,]. Geophys. Res., 88(CJJ), 6719-6736, 1983. 

Cicerone, R.J., LE. Heidt, and W.H. Pollock, Measurements of 

atmospheric methyl bromide and bromoform, J. Geophys. Res., 

93(D4), 3745-3749, 1988. 

Finlayson-Pius, BJ., F.E. Livingstone, and H.N. Berko., Ozone 

destruction and bromine photochemistry at ground level in the Arctic 

spring, Nature, 343, 622-625, 1990. 

Oltmans, SJ., R.C. Schnell, PJ. Sheridan, R.E. Peterson, J.W. 

Winchester, S.-M. Li, P.P. Tans, W.T. Sturges, L.A. Barrie and J.D. 

Kahl, Seasonal surface ozone and filterable bromine relationship in 

the High Arctic, Atmos. Environ., 23, 243 1-2441 , 1989. 

Sturges, W.T. and L.A. Barrie, Chlorine, bromine and iodine in arctic 

aerosols, Atmos. Environ., 22, 1179-1194, 1988. 

Sturges, W.T., R.C. Schnell, S. Landsberger, J.M. Harris, and S.-M. Li, 

Chemical and meteorological influences on surface ozone 

destruction at Barrow, Alaska during spring 1989, Atmos. Environ., 

in press, 1991a. 

Sturges, W.T., C.W. Sullivan, R.C. Schnell, L.E. Heidt, W.H. Pollock, 

and Hofmann, DJ., Symposium on the Tropospheric Chemistry of 

the Antarctic Region, edited by A. Hogan and S.L Bowen, 

Cooperative Institute for Research in Environmental Sciences, 

University of Colorado, Boulder, Colorado, June 3-6 1991, US Army 

Cold Regions Research and Engineering Laboratory Special Report 

(Abstracts)91-IO, p. 55, 199 l b. 

119 
Radon as a Baseline Selection Criterion at Mauna Loa Observatory 

s. WHITI1.ESTONE 

Australian Nuclear Science and Technology Organization, PMB l, Menai, N.S.W. 2234, Australia 

L.P. STEELE 

CS/RO, Division of Atmospheric Research, Mordialloc, Victoria 3195, Australia 

S. RYAN 

NOAA, Mauna Loa Observatory, Hilo, Hawaii 

1. INTRODUCTION 

Al the observatories studying the global changes in trace 

constituents of the atmosphere, knowledge of the air history 

in weeks prior lo sampling is of great importance in the 

interpretation of the results. Local emissions and meteorology can significantly influence the concentrations of trace 

gases. Keeling et al. [1976] demonstrate the impact on the 

carbon dioxide record of the upslope winds al MLO. 

Because of this, il is common practice to select sampling 

limes or flag data so that a record can be obtained under socalled "baseline" conditions [Thoning et al., 1989]. In this 

context, baseline is usually interpreted to mean that the 

sample is representative of a large volume of the atmosphere. 

This is essential for comparing measurements to current 

fixed-grid model simulations of trace gas levels in the global 

atmosphere because the size of grid boxes is large, and the 

atmosphere is assumed uniform in each box at each time step 

of the simulation [Fung et al., 1991]. 

While mu<lt:l verification an<l intercomparison of data 

from different species requires a conformity of sampling 

conditions, the definition of baseline is notoriously 

species-dependent. In practice, a minimum requirement is 

made that does not exclude an unacceptable amount of data, 

then additional criteria are added for each species. One aim 

of the present study is to investigate the possibility of 

upgrading the minimum requirement to increase the overlap 

of sampling conditions for different species. Thus at MLO, 

the present minimum requirement for baseline is non-upslope 

conditions to avoid local influence. However, most trace 

gases are perturbed by passage over land or cities. It is, 

therefore, suggested that the criteria for baseline selection 

should include indicators of recent contact with land. 

Local wind speed and direction are important in determining whether atmospheric trace species measurements made al 

MLO are free from local Hawaiian influence. Dewpoint and 

temperature help to determine the extent of mixing of the 

free troposphere with the boundary layer. However, the 

local meteorological data cannot indicate where the air has 

been on scales of more than a few hundred km. Trajectory 

calculations provide a good general idea of the path the air 

has taken, but there are three important limitations: the 

information is not immediately available, so that it cannot be 

used to operate conditional samplers; the liming accuracy is 

generally no better than several hours, so the data cannot be 

used to select pollution episodes during periods of change; 

and even though air may have passed over land, it may not 

actually have mixed with air from the surface. Tracer 

techniques offer an objective, real-time criterion for baseline 

selection provided the tracer can be measured continuously 

with suitable sensitivity. 

Radon has been widely used as a tracer for air masses 

which have recently passed over land because it is an inert 

gas unaffected by chemical interactions in transit, and its 

emanation rate from land is about one hundred times the rate 

from the ocean [Wilkening and Clements, 1975]. Its half-life 

of 3.8 days ensures that it does not build up in the atmosphere. It has been measured continuously al MLO since May 

1989, and it has been demonstrated to be highly sensitive to 

the influx of air from distant continents [Whittlestone et al., 

1991]. Gras et al. (1991] have shown that CN are in some 

ways a better tracer than radon for polluted air masses for 

distances up to the order of a few hundred km from the 

source, but that for the longer distances involved at MLO, 

radon is to be preferred. 

Recent CN data results from the radon program at MLO 

were measured by the CN counter incorporated into the 

radon detection system. Radon is correlated with CN and 

other gases, C02, chlorofluorocarbons, N20, and CH4, and 

evaluated for inclusion with other criteria in defining the 

aged baseline condition at MLO. 

2. RADON, CN Ai'\/D AIR MASS TRAJECTORJES 

In selecting data, it was necessary to exclude samples 

perturbed by local radon sources. Wind direction and speed 

are strong indicators of the likelihood of local contamination, 

and the value of requiring winds to be non-upslope is well 

established. However, it is reasonable to expect some 

contamination in air in the non-upslope sector for a short 

time after a change in conditions from upslope. To avoid 

this, the meteorological baseline condition can be required to 

be established for some time before sampling. A period of 2 

hours has been employed in the subsequent analysis. Thi.s 

extended local meteorological baseline criterion resulted in 

three groups of data: about half in the baseline group, a 

quarter in the locally affected upslope group, and the group 

whose members did not fit into the first two. 

For the study of interrelationships between radon, CN, and 

10-day isobaric back trajectories ending at MLO, we have 

selected from throughout 1990 a number of periods (totalling 

66 days) from all seasons. For each of these days, back 

trajectories were obtained for air parcels al both the 500 hPa 

and 700 hPa pressure levels, for arrival times at MLO of 

0000 and 1200 hours GMT. To account for timing uncertainties in the calculation, both the radon and CN baseline 

120 
data have been averaged over the 12-hour period centered on 

the calculated time of arrival of the air parcels. We have 

then used the local meteorological data to classify the air 

masses as either "free troposphere" (FT) or "boundary layer" 

(BL). When the local dewpoint was less than -lO'C, the air 

mass was classified as FT, and the 500 hPa trajectory was 

used to examine the relationships. For dewpoints above 

-lO'C, the classification was boundary layer (BL) and the 

700 hPa trajectory used. The data included in this BL 

category represent times when strong synoptic flows lead to 

mixing between the midtroposphcrc and the boundary layer. 

The fraction of the time that the dcwpoint lay in the -5' to 

-15'C range was small, so the analysis is not sensitive to the 

exact demarcation point chosen to separate the categories. 

A procedure was devised to test the extent to which radon 

and CN concentrations correlated with trajectories passing 

over land. Frequency distributions of FT radon and CN 

concentrations were formed for the selected trajectory 

classes (Figure 1 ). In the case of radon there is a strong bias 

towards high radon concentrations when the trajectory path 

started over land. The median concentrations of both radon 

and CN for all trajectories were calculated and used as 

convenient reference levels. The fractions of radon and CN 

concentrations less than these reference levels were 

determined for the land and sea trajectory groups. For our 

FT category, 71 % of the radon concentrations for land 

trajectories exceed the reference level, clearly indicating that 

the high radon is associated with trajectories over land. As 

expected in the group associated with sea trajectories, a 

lower fraction of the radon concentrations, 33%, arc above 

the reference level. A separation factor, S, was obtained by 

dividing the land fraction (71%) by the sea fraction (33%) 

for FT radon, yielding a value of 2.2 for S. This procedure 

was carried out for both r adon and CN in the FT and BL 

categories (Table 1). 

For the BL category, both CN and radon distributions are 

strongly separated according to whether or not the trajectories have passed over land. This is also true for FT radon; 

but for FT CN, the trajectories provide no separation, as the 

CN concentration distributions are the same for land and sea 

traj ectories (Figure 1). Evidently passage over land often is 

accompanied by some vertical mixing between the BL and 

the FT. It appears that during or shortly after mixing, 

processes such as precipitation (which results in the low 

dewpoint of FT air) remove CN but not radon. 

TABLE 1. Performance of Trajectory Calculations in 

Separating High Radon and CN Concentrations 

From Low Values 

Sample Category 

Upslope 

Boundary layer 

Free troposphere 

Separation factor 

Radon CN 

1.5 l. l 

2.1 1. 8 

2.2 1.0 

'40 

30 

20 ....., 

~ 

>- 10 u 

z 

' -. 

I ALL TRAJECTORIES 

>10 DAYS OYER OCEAN 

>1 DAY OYER LAND 

CN 

~ 0 f--.l.--'--i--'---'--'--l--''--J.._.l_..r:=_:J.__L.-L--l--''--'--J-~ - - I 8 30 Cl: 

i... 

20 

10 

I 

200 '400 600 800 

CN (cm - 3 ) and Rod on (mBq m - 3 ) 

Fig. I. Normalized frequency distributions of radon and CN 

concentrations in free tropospheric air. 

Upslope air is considered for completeness. It is BL air 

with added radon and CN uncorrelated with the air mass 

origin. As expected, the separation factors are less than for 

the non-upslope BL samples. 

3. COMPARISON OF CN AND RADON 

In this section CN are evaluated as a tracer of continental 

influence using radon as the baseline criterion taking hourly 

data from July 1989 through June 1990. The extended 

meteorological baseline selection criterion was applied as in 

Section 2, yielding upslope, BL, and FT data groups. Not 

only is the sample larger than was possible with the 

trajectory analyses, but the timing uncertainty has been 

removed. Since there are considerable seasonal changes of 

CN [Gras, 1990)] and radon, the data have been put into 

summer and winter groups. 

The upslope dependence of CN on radon is only moderate 

(Figure 2) because the fetch over land is so short that paths 

by a CN source may not always pass over deep soils 

emanating radon. Also, the highest radon concentrations are 

from distant land while the main CN sources are local. In 

the non-upslope samples, the distributions have no dependence on radon below 0.1 Bq m·3. This is similar to the 

results reported by Gras et al., (1991] at Cape Grim 

(Tasmania, 4l'S, 145'E) and Macquarie Island (55'S,159'E) 

and supports the use of 0.1 Bq m·3 as a baseline criterion for 

radon. 

To allow comparison to the analysis based on the 

traj ectories, the tentative 0.1 Bq m·3 baseline criterion has 

been used as a reference level to separate the CN distributions in a similar fashion to that done in Section 2. The 

values are 2.4 upslope, 1.6 boundary layer, and 1.5 free 

troposphere which should be compared to the values in Table 

1 for CN selected by trajectory of 1.1, 1.8 and 1.0 respectively. It is expected that the separation factors should be 

greater in the upslope winds using the radon criterion 

because a high proportion of the CN and radon in this sector 

121 
z 

u 

········ ···· [. -~=·· ·····; 

0.01 0.05 0.1 0 .3 SUt.4t.4[R 0.05 0 . 1 0 .3 WINTER RADON (Bq m-3 ) 

UPSLOPE 

PERCENTILES 

10-90 

25-75 - - t.4EDIAN 

fig. 2. CN concentration frequency distributions versus radon 

concentrations at MLO in 1989-1990. 

is local and independent of the long range path. What is 

more surprising is the relatively high separation factor in the 

free troposphere. In the events selected for trajectory 

analysis, it appeared that no CN survived the vertical mixing 

which raised radon to the FT. A study of CN, radon, and 

traj ectories to resolve Lhis apparent inconsistency may help 

to understand the conditions under which vertical transport 

of reactive species is favored. 

4. RADON APPLIED TO SELECTION OF TRACE 

GASES AT MLO 

This is a preliminary examination of the value of 

including radon in the definition of baseline conditions for 

sampling C02 (measured during January 1991), CH4 (July 

1989 through June 1990), N20, CFC-11 , CFC-12, CC14, and 

CH3CCl3 (all for November 1989). In all cases hourly data 

are used. 

For simplicity of interpretation, the gases were selected 

using the extended meteorological baseline criterion to 

eliminate local influence. During the short data period 

studied, C02 , CFC-11, CFC-12, CC14 , CH3CC13, and Np all 

exhibited strong dependence on concurrent radon concentration. The data being grouped into radon bins 50 mBq m·

3 

wide centered on the data points is shown in Figure 3. The 

error bar indicates one standard deviation of the mean for 

each bin. It is notable that the correlations are positive for 

all species except N20. This reflects the fact that of the six 

gases, N20 is the only one for which oceanic sources can 

predominate (IPCC, 1990). 

To illustrate the power of radon in characterizing air 

masses, the CH4 data have bl.3 placed in four groups 

defined by range of radon concentration and monthly 

averages have been obtained (Figure 4). It is clear that 

during much of the year, radon and CH4 are strongly 

positively correlated. Selection of CH4 using the 0.1 Bq m·3 

., 

...J 

u 

u 

., 

::c 

u 

> 

D 

a. 

~ 

0 

N 

z 

G0960 CCL4 - 109 (pptv) 00000 C02 - 354 (ppmv 

3 .... 

0 

u 

" c 

0 

... 

...J 

u 

u 

17 o1-·~~~~~~~~ ...... ~oeeeo~ ~~c~r-c~11~- 60~~ ........ o ~ 

l10 GBB8EJ CFC12 - -460 ! 

:::=:; u 

10 t; 

" c 

0 

t'.' 3050~~~~~~~~~~~~~~ ~0 u 100 200 300 400 500 0 100 200 300 400 500 

RAOON (mBq m- 3) RADON (mBq m- 3) 

Fig. 3. Trace gases versus radon at MLO in non-upslope winds. 

baseline criterion yields a well-defined seasonal cycle with 

an amplitude of about 25 ppbv and high period from 

September through February. A marked feature of the 

"baseline" group is the small size of the standard deviations. 

We are investigating the implications of the results suggesting that the selection of CH4 during periods of low radon 

may offer a more realistic seasonal cycle with which to 

compare the model simulations of Fung et al., (1991). 

5. CONCLUSIONS 

Meteorological data are primary indicators of the upslope 

air which is subject to local land influence. Once upslope air 

is identified and removed from the analysis, dewpoint and 

wind direction provide no clues to the degree of recent land 

> 

D 

a. 

1730 

1720 

~1710 

w 

z 

< 

~ 1700 w 

::i 

1690 

1680 

0-100 mBq m-l 

00000 100-200 CBTD200-400 08llilEJ ) 400 -- ANNUAL TREND CJ ' 

/ -~ -o 0 <trl-o - ""' I

I -~' ' 

Q v 'ff 

0 

16 70 '--J~U_,L_A~U~G~S-E~P~O T,..._N EC_.._J_A_N,..._F_EB_.._M _._ R....._M_AY-'-J-U-N~ 

1989 1990 

Fig. 4. Monthly averages of methane selected by radon concentration range at MLO. Samples during upslope conditions have been 

excluded. 

122 
influence. Ana lysis using air trajectories s hows that radon 

correlates strongly with passage over land (Table 1 ), while in 

the c ase o f CN the correlation is not consistent. This supports 

the use of radon as a principal indicator of potential perturbation of the trace gas records at MLO caused by the recent 

passage of air masses over land. 

The application of radon as a selection criterion for other 

trace gases has demonstrated that the data from the MLO 

radon instrument provide a powerfu l means of gaining insights 

into the variability of these trace gas records. In particular, 

there is a strong indication that CH4 selected from times at 

which the radon is below 100 mBq m·3 is much better m atched 

to the output of global models than the full record. It is, 

therefore, likely the radon baseline criterion is necessary for 

verific ation of models for any gas influenced by passage over 

land. 

Acknowledgments. The authors are grateful to CMDL for 

providing the laboratory space and technic al support for the 

MLO work and its staff members, P. T ans for the C02 data, J. 

Elkins for other trace gas data, G. Herbert for the meteorological data, and J. Harris for the trajectories. The work would not 

have been possible without the support of technical staff at 

CSIRO and ANSTO. 

6. R EFERENCES 

Gras, J.L., Baseline atmos pheric condensation nuclei at Cape 

Grim 1977-1 987, J. Atmos. Chem ., 11, 89-106, 1990. 

Gras, J.L., and S. Whittlestone, Radon and CN: Complementary 

tracers of polluted air masses at coastal and island sites, 

M ARC-II conference of the Ame ri can Nuclear Society (ANS), 

April 22-26, 1991, LaGrange, IL, 1991. 

Fung I., J. John, J. Lerner, E. Mathews, M. Prather, LP. Steele, 

and P.J. Fraser, Th ree-dimensional model synthesis of the 

global methane cycle, J . Geophys Res., 96, 13,033 -13,065, 

199 1. 

IPCC, Climate Chang e, the !PCC Scientific Assessment, edited by 

J.T. Haughton, G.J. Jenkins, and J.J. Ephraums, Cambridge 

University Press, Cambridge, pp. 7 -40, 1990. 

Keeling, C.D., R.B. Bacastow, A.E. Bainbridge, C.A. Ekdahl, P.R. 

Guenther, L.S. Waterman, and J.F.S. Chin, Atmospheric carbon 

dioxide variations al Mauna Loa Observatory, Hawaii, Tel/us, 

28,538-55 1, 1976. 

Miller J.M., A five-year cl imatology of back trajectories from the 

Mauna Loa Observatory, Hawaii, Atmos. Environ., 15, 

1553-1558, 1981. 

Thoning , K.W., P.P. Tans, and W.D. Komhyr, Atmospheric 

carbon dioxide at Mauna Loa Observatory, 2, Analysis of the 

NOAA GMCC data, 1974-1985, J. Geophys. Res., 94, 

8549-8565, 1989 . 

Wh ittlestone, S., E. Robinson, and S . Ryan, Radon at the Maun a 

Loa Observatory: Transport from distant continents, J. Atmos 

Res., in press, 199 1. 

Wilkening, M.H., and W.E.Clements, Radon 222 from the Ocean 

surface, J . Geophys. Res. , 80, 3828-3830, 1975. 

123 
Seasonal Amplitude Variations in C02 in the Northern Hemisphere 

T. P. WHORF A>'\D C. D. KEELIXG 

Scripps lnstituJion of Oceanography, La Jolla, California 92093·0220 

1. INTRODUCTION 

Cooperative programs of C02 measurements at Point 

Barrow, Alaska (BRW), and Mauna Loa, Hawaii (MLO), 

between Scripps Institution of Oceanography (SIO) and 

CMDL continued during 1990. Air samples were collected 

in 5-L glass flasks on approximately a weekly basis since 

1960 al MLO and since 1974 al BRW. In addition, SIO 

continued to monitor atmospheric C02 concentrations at 

MLO on a continuous basis using the NDIR gas analyzer 

installed on site in 1958. 

Recently, data al these two sites, as well as a third 

northern hemisphere site al SIO, were interpreted in order to 

look for recent changes in the amplitude of the seasonal 

cycle in C01 concentration. Such changes were observed 

previously in the MLO continuous record [Bacastow el al., 

1985), as well as at Ocean Station P, which was discontinued 

in 1981 [Keeling el al., 1985). Air samples were collected 

on the Scripps Pier since 1969 and are supplemented by two 

several-year periods of continuous C02 measurements. 

Together these three sites provide the longest available 

records of C02 concentration in the northern hemisphere, 

where the variations are mainly attributable to the metabolic 

activity of land vegetation [Keeling et al., 1989, p 175). 

2. DATA AND ANALYSlS 

All flask samples were first evacuated al the Scripps 

laboratory and then later returned from the field to be 

analyzed for their C02 concentration with an NDIR gas 

analyzer of the same design as that installed al MLO. 

Calibrations have continued with reference gases similar to 

those used al MLO [Keeling el al., 1986). 

Air samples were rej ected if pairs did not agree within 

0.40 ppm (singlets rejected also) or if found to be outliers 

having a residual greater than three standard deviations from 

a smooth curve fit describing the seasonal and interannual 

variations. The function chosen in the fitting process uses a 

sum of four harmonics to describe the seasonal variations 

and a cubic spline [Reinsch, 1967) to describe the interannual variations. A gain factor is used to model an approximately linearly increasing seasonal amplitude variation 

[Keeling el al., 1989, pp 167, 176). This simple model of 

increasing annual C02 cycles was introduced when it became 

clear in our longer C01 records that there were significant 

increases in the seasonal amplitude of col concentration. 

Figure 1 shows the results of such fits made to the C01 

observations collected from all of our northern hemisphere 

stations. BRW data were augmented to include continuous 

C01 data measurements made by Kelley, 1969 during the 

period 1961-1967, so as to show possible variauons in the 

seasonal amplitude of C01 over a longer period. Data at three 

additional sites are shown in the figure: Alert, N.W.T (82'N, 

62'W); Cape Kumukahi, Hawaii (19'N, 155' W); and 

Christmas Island (2'N, 157'W). A cooperative program at 

Alert between SIO and the Atmospheric Envirorunent Service 

of Canada has existed since 1985 and at Cape Kumukahi 

between SIO and CMDL since 1979. Both the Alert and Cape 

Kumukahi C01 records arc, however, relatively short and can 

thus provide only supporting evidence to the results from the 

longer stations. The location of Christmas Island near the 

equator makes it more useful for observing the large local 

fluctuations due to changes of pC01 in equatorial seawater 

[Keeling el al., 1989, pp. 202-208]. 

NOR'THIRN H!:VISPHERE 

ns 

))0 

Jl'i ~ ~ ~ ~ ~ M ~ ~ ~ , ~ ~ ~ ~ ~ ~ ~ ~ 

YEAR 

Al.1' 

82'N 

?T9 

"71"S' 

uo 

JJ'N 

\ILO 

20'N 

CHR 

2'N 

Fig. I. ~onthly average C01 data at current SIO nonhcm 

hemisphere stations fit by the function described in text. Early 

BRW data from Kelley, 1969; MLO data are from continuous record 

and Christmas Island data (1977-1991) include Fanning Island data 

(4'N) from 1972 to 1983. 

124 
3. RESULTS 

Figures 2-5 show seasonal amplitudes computed annually 

by least-square fitting an annual factor times the same set of 

four harmonics derived in the overall fit, but for each year 

independently. The harmonic function is thus phase locked 

by the fit to the overall data set. An overall gain factor "A" 

for the entire record is also computed where the annual 

factor is assumed to vary linearly with time by the expression, "I +At," where t denotes time, here expressed relative 

to January l, 1980. A linear fit made to the set of independent annual amplitudes for a given station gives approximately the same gain factor. Note that in the figures 

the annual factors are computed for times relative to the 

midpoint of the record (i.e., the amplitudes are relative to the 

mean annual cycle). Also , for each station the most recent 

annual amplitude is preliminary since the year is not 

complete. Table 1 lists the gain factors for each of the three 

northern hemisphere stations shown in Figures 2-5, as well 

as at Ocean Station P where a solid estimate was obtained up 

to 1980. Standard .:rror estimates for the computed gain 

factors are also listed. These range from 4% to 26%. MLO 

seasonal amplitudes arc shown separately for the continuous 

C02 data and the C02 data derived from flask samples. 111e 

latter data set is, of course, noisier than the continuous 

record because of obvious differences in sampling and 

smoothing, but it is useful nonetheless to see how well the 

records agree, since most of the data at other stations are 

derived from air sampling by flasks. Smoothing of the MLO 

continuous record results from omitting C02 data that appear 

to be contaminated by local sources or sinks, whereas in the 

case of flask sampling it is not always so clear what local 

effects may be present, even if conditions seem adequate for 

sampling. By sufficiently frequent sampling, however, and 

omitting flask data that have fit residuals greater than three 

standard deviations, these effects were minimized. The 

distribution and quantity of data throughout any given year 

will necessarily impact the seasonal amplitude for that year, 

so that in some years the computed amplitudes may be 

unreliable. One such year, 1976, was omilled in the case of 

I. zo 

CJ I 15 

Cl 

~J.10 

:i 

~I. OS < 

~ 1.00 

§ .95 

w 

"' .90 

.es 

60 65 70 75 

YEAR 

eo PS 0() 95 

Fig. 2. Relative amplitudes of the seasonal cycle in atmospheric 

C02 at BRW where time is relative to the midpoint of the record 

(also true for Figures 3-5). 

w 

> 

;: .90 

.:s 

w .es 

"' . eo 

. 75 

.70......_~ ........ ~~~~~ .................. ~~~~~~~~~~ ......... ~ 

H W ~ M ~ ~ ~ 90 95 

YEAR 

Fig. 3. Relative amplitudes of the seasonal cycle in atmospheric 

C02 at La Jolla Pier. 

I. IS 

~J.10 :::;, 

1-:::i I.OS a. 

~ .95 

j 

J.00 ······ ·~················ ····· 

l>! .90 

.es 

-~'--~ ........ ~~~~~L.......~.-.L~~-'-"~~~~ ........ ~~~ 

H W ~ M ~ ~ ~ 90 95 

YEAR 

Fig. 4. Relative amplitudes of the seasonal cycle in atmospheric 

C02 at MLO. Data used in fining are weeklies averaged from 

continuous record. 

I. IS 

~J.10 :::;, 

1-

:JI.OS 

a. 

~1.00 

§ .95 

l>! .90 

.85 

60 65 70 7S 

Yf.AR ~ 85 

Fig. 5. Relative amplitudes of the seasonal cycle in atmospheric 

C02 at '.'.1LO. Data are from flask samples. 

the La Jolla amplitudes. Generally a good quality of data at 

the La Jolla station has been maintained as long as care was 

taken in choosing sampling times, despite the proximity of 

local sources. Recently, maintenance of a continuous record 

has been quite helpful in achieving this goal. 

125 
TABLE 1. Annual Rate of Increase in the Amplitude 

of the Seasonal Oscillation of Atmospheric 

C02 at Various Locations 

Approx. Inclusive dates Rate of increase* 

Location Latitude of observations (%) 

BRW 71'N July 1961-Sept. 1967 1.04 ± 0.070 

Jan. 1974-April 1991 

Station P 50'N May 1969-June 1981 0.738 ± 0.259 

La Jolla 33' N Jan. 1970-June 1991 1.247 ± 0.200 

MLO 20'N March 1958-June 199 1 0.535 ± 0 .. 042 

(continuous) 

MLO 20'N March 1960-June 1991 0.750 ± 0.121 

(flasks) 

*With reference to January 1, 1980. 

In addition to short-term or local influences on C02, there 

are interannual changes usually related to El Nino events 

[Keeling et al., 1989, p. 180]. These changes significantly 

affect the computed annual values of seasonal amplitude 

since the involved frequencies overlap. Comparison of 

seasonal amplitude plots, with plots showing the correlation 

o f El Niii.o events with interartnual variations in C0 2, r eveal 

that the influence of one on the other is small, except for 

Christmas Island that lies close to the equator in the Pacific 

Ocean. Though separation o f the two modes of variation is 

mathematically possible by subtraction of the interannual 

variation preceding computation of the annual seasonal 

amplitudes, it is not discussed here. 

4. CONCLUSIONS 

The above analyses and plots suggest that seasonal 

amplitudes of C02 concentration in the northern hemisphere 

may be on the upswing again after nearly a decade with little 

apparent variation. All three of the long-term northern 

hemisphere records analyzed here suggest that this is the 

case. Previously; it appeared that the seasonal C0 2 

amplitudes had 

reached a maximum in the early 1980's and had declined to 

some extent since then, but it now appears that this may 

merely be a temporary pause in an overall rising trend in 

seasonal amplitudes. 

Results from Station Alert, available only since 1985, 

tend to confirm the existence of a recent upturn in seasonal 

amplitude, as suggested by the fact that the average 

amplitude for the first half of the record relative to the mean 

is 0.97 while the average of the last three years is 1.05. A 

linear fit to the annual C02 amplitudes yields a gain factor of 

1.52% per year with an error of 0.71 % per year. Cape 

Kumukahi data show a relatively constant or slightly 

declining seasonal amplitude over the years 1980-1989, as 

do MLO continuous data, but due to somewhat noisier data 

recently, are inconclusive as to the existence of a recent 

upturn. Further measuremen ts at these, and other such sites, 

should serve to verify whether or not a continuing rise in 

seasonal C0 2 amplitudes is occurring now. 

5. REFERENCES 

Bacastow, R. B., C.D. Keeling, T.P. Whorf, Seasonal amplitude 

increase in atmospheric C02 concentration al Mauna Loa, 

Hawaii, 1959-1982,J. Geophys. Res., 90, 10,529-10,540, 1985. 

Keeling, C. D., T.P. Whorf, C.S. Wong, R.D. Bellagay, The 

concentration of atmospheric carbon dioxide al ocean weather 

station P from 1969 to 1981, J. Geophys. Res., 90, 

10,511-10,528, 1985. 

Keeling, C. D., P.R. Guenther, and D.J. Moss, Scripps reference gas 

calibration system for carbon dioxide-in-air standards: Revision 

of 1985, Report No. 4 of the Environmental Monitoring 

Programme of the World Meteorological Organization, Geneva, 

34 pp. and Addendum, 43 pp., 1986. 

Keeling, C. D., R.B. Bacastow, A.F. Carter, S.C. Piper, T.P. Whorf, 

M. Heimann, W.G. Mook, and H. Roeloffzen, A threedimensional model of atmospheric C02 transport based on 

observed winds: !. Analysis of observational data, in Aspects of 

Climate Variability in the Pacific and the Western Americas, 

edited by D. H. Peterson, Geophysical Monograph American 

Geophysical Union, 55, 165-236, Washington, DC, 1989. 

Kelley, J. J., Jr., An analysis of carbon dioxide in the arctic 

atmosphere near Barrow, Alaska 1961 to 1967, Contract 

NOOOJ4-67-A-0103-0007 NR 307-252, 172 pp., Scientific Report 

of the United States Office of Naval Research, 1969. 

Reinsch, C. H., Smoothing by spline functions, Nwnerische 

Mathematik, JO, 177-183, 1967. 

126 
10. International Activities, 1990 

In February the Soviet research ship Akademik Korolev 

was in port for 4 days to load a number of U.S. scientists and 

the ir equipment before embarking on the third SAGA cruise 

directed toward research on atmospheric and oceanic 

interactions. 

In August Tom Defoor was invited to visit several 

laboratories in the U .S.S.R., especially the principal lidar 

developmental facility at Obninsk, near Moscow. This 

U.S.S.R. visit also included attendance at the International 

Lidar Conference in Tomsk, Siberia. Two papers, coauthored with other CMDL staff, were presented in the 

U.S.S.R. In Obninsk, Tom Defoor presented a report 

entitled "Stratospheric Aerosol Measurements at Mauna Loa 

Observatory 1974-1990: The Normalization and Calibration 

Problem." At the Lidar Conference in Tomsk, U.S.S.R., a 

poster paper was presented by Tom Defoor entitled: 

"Uncertainties in the Application of Lidar for Observing 

Stratospheric Aerosol Optical Thickness." 

B. Bodhaine participated in the Chemistry of the Global 

Atmosphere, the Seventh International Symposium of the 

Commission on Atmospheric Chemistry and Global 

Pollution, held 5-11 September in Charnrousse, France. He 

presented a paper entitled "Long-range transport and annual 

cycles in aerosol data at background stations." 

L. Waterman visited CSIRO Division of Oceanography in 

Hobart, Tasmania, on June 18. Contact was made with D. 

Mackey whose group is developing an automated system for 

the underway measurement of pH, salinity and chlorophyll in 

surface ocean waters to calculate the air-sea exchange of 

C02. The apparatus is designed for deployment on both 

research and commercial vessels. Contacted also was R. 

Bailey, who heads the CSIRO "ships of opportunity" 

program, which is utilizing 11 commercial vessels to obtain 

ocean temperature profile measurements. 

On June 21-22, L. Waterman visited the CGBAPS at 

Smithton and Cape Grim, Tasmania, to discuss with station 

personnel the collection of air samples in 2.5-L two-valve 

flasks with the new MAKS sampler. The CSIRO Division of 

Atmospheric Research at Aspendale was visited on June 25. 

Contacts were made with all staff involved with the 

cooperative Australian/USA air sampling at Cape Grim and 

the CMDL baseline observatories. The Trace Gases Group 

was briefed on CMDL Carbon Cycle Group activities. 

On July 2, L. Waterman met with Ng Swee Khoon, 

Operations Manager, C.F. Sharp Shipping Agencies in 

Singapore for more discussions on a program to collect air 

samples in the South China Sea from the Chevron vessel 

MIV Carla I/ills [CMDL Summary Report 18, 1989). 

P. Tans participated in a workshop organized by the 

International Union of Pure and Applied Chemistry in 

Petten, The Netherlands, July 4-6, on the "Assessment of 

Uncertainties in the Projected Concentrations of Carbon 

Dioxide in the Atmosphere." 

L. Waterman visited TRANET Station 558, MahC, 

Seychelles Islands, July 4-7, and met with New Mexico State 

staff members L. Bradford and C. Garcia. Training was 

provided on the operation of the MAKS and regular 

collection of air samples with the new equipment was 

initiated. Sampling problems associated with tropical 

climate were identified and discussed . Three sites used for 

the collection of air samples under different wind regimes 

were inspected. 

En route from the Seychelles to Boulder, L. Waterman 

visited J. Young Scientific Glassware Ltd. (Acton, England) 

on July 9; Blue Star Management Ltd. (London) on July 10; 

and the British Antarctic Survey (Cambridge) on July 11. J. 

Young manufactures the 0-ring valves used on the NOAA 

flasks. A tour of the shop was provided, and quality control 

problems associated with valve breakage were discussed. 

Contact was made with Capt. W. Houghton Boreham at Blue 

Star who was briefed on the success of the MIV Southland 

Star sampling. Information was obtained on the operation of 

large container vessels circumnavigating the southern oceans 

at high latitudes, and the possibility of air sampling on one 

of these carriers, the M!V ACT 7. L. Waterman also met with 

S. Morrison of the British Antarctic Survey (BAS) to discuss 

the air sampling at Bird Island, South Georgia, and Halley 

Bay, Antarctica. Problems of sampling in extreme cold 

weather were discussed and possible solutions were 

suggested. Plans were made for BAS personnel to visit 

Boulder. 

S. Morrison, S. Colwell, and J. Cooper, of the BAS, 

visited Boulder August 15-21 to receive a briefing on the 

NOAA sampling network operations and training with the 

MAKS. Colwell is assigned to Halley Bay and Cooper to 

Bird Island for the 1991-1992 tour of duty. Two MAKS 

units were hand-carried to BAS to take to the stations. 

P. Tans chaired the WMO Meeting of Experts on Carbon 

Dioxide Concentration and Isotopic Measurement Techniques, on October 14-19, Lake Arrowhead, California. 

Y.S. Chung, Korea National University of Education, 

visited Boulder on November 13 and received training with 

the MAKS unit and 2.5-L two-valve flasks. The establishment of a sampling site on the Tae-ahn Peninsula (TAP) 

on the west coast of South Korea was discussed. Chung 

hand-carried a MAKS to Korea and the first samples were 

collected at TAP on November 24. 

Under the auspices of the WMO, calibration checks were 

conducted on 15 foreign Dobson ozone spectrophotometers 

calibrated in the past by NOAA-CMDL scientists. The work 

was performed July 21-August 9, 1990, at Arosa, Switzerland 

(see Section 5.1.5). Three additional foreign Dobson 

instruments were calibrated for the first time. While enroute 

to the Arosa Dobson instrument comparisons, French Dobson 

instrument 49 was calibrated at Haute Provence, France. 

J. Harris traveled to Seoul and Cheongwon, South Korea, 

in September to present two seminars concerning trajectory 

models and the transport of air pollution and trace gases. 

These were given at the Korea National University of 

Education and the Korean National Institute of Environmental Research. Discussions were held to determine areas for 

collaborative research. 

127 
In November S. Oltmans traveled to Bermuda Lo calibrate 

the AEROCE network surface ozone monitor. 

J. Butler, J. Elkins, T. Swanson, and B. Hall participated on 

Legs 1 and 2 of the third Soviet-American Gas and Aerosol 

Experiment (SAGA II[), conducted from February through 

April 1990, on the Soviet research vessel Akademik Korolev. 

James Butler met with collaborating Soviet scientists in Seattle 

during August 1990 and in San Francisco during December 

1990. J. Butler also gave talks on SAGA lII results at 

NOANPMEL and at the AGU meeting in San Francisco. 

J. Elkins was an invited participant in the European 

Workshop on Nitrous Oxide Emissions held in Lisbon, 

Portugal, June 6-8. 

J. Elkins gave an invited presentation at the 7th International Symposium of the Commission on Atmospheric 

Chemistry and Global Pollution (CACGP) held in Chamrousse, France, September 5-11. 

J. Elkins worked with P. Fraser of CSIRO on installing a 

new GC system and on making measurements from ice 

cores. 

128 
11. Publications and Presentations by CMDL Staff, 1990 

Bodhaine, B.A., Aerosol instrumentation on the NOAA WP-3D 

during the third Arctic gas and aerosol sampling program, paper 

A51 B-10 presented al the American Geophysical Union Fall 

Meeting, San Francisco, December 3-7, 1990. 

Bodhaine, 8.A., and J.M. Harris, Long-range transport and annual 

cycles in aerosol data al background stations, paper presented al 

the Seventh International Commission on Atmospheric 

Chemistry and Global Pollution, Chamrousse, France, September 

5-11, 1990. 

Bodhaine, B.A., and M.K. Shanahan, Condensation nucleus and 

aerosol scattering extinction measurements at the South Pole 

Observatory: 1979-1988, NOAA Data Rep. ERL CMDL-1, NOAA 

Climate Monitoring And Diagnostics Laboratory, Boulder, CO, 

148 pp., 1990. 

Bodhaine, B.A., J.J. DeLuisi, J.F. Boatman, M.J. Post, and J.M. 

Rosen, The front range lidar, aircraft, and balloon experiment, 

NOAA Data Rep. ERL CMDL-2, NOAA Climate Monitoring and 

Diagnostics Laboratory, Boulder, CO, 27 pp., 1990. 

Butler, J.H., Global wanning and ozone depletion, paper presented 

al Back to the Future: A Workshop on Change, Denver Museum 

of Natural History, Denver, CO, November 28, 1990. 

Butler, J.H., Global warming, ozone depletion, and trace gases in 

the ocean and atmosphere, paper presented at Humboldt Stale 

University, Arcata, CA, September 6, 1990. 

Butler, I.H., Measurement of CFC-22, CFC-113, and Halons 1211 

and 1301 in the atmosphere, paper presented at the 1990 Johnson 

Conference, Our Changing Atmosphere: Challenges in 

Measurement Technology, sponsored by the American Society 

for Testing Materials Commiuee D-22 on Sampling and Analysis 

of Atmospheres, Johnson, VT, July 8-13, 1990. 

Butler, J.11., J.W. Elkins, T.J. Conway, B.D. Hall, T.H. Swanson, 

and T.M. Thompson, Reflections of surface-ocean trace gas 

concentrations in the atmospheric boundary layer: Implications 

for air-sea exchange and atmospheric transport, EOS, 71(43), 

226, American Geophysical Union Fall Meeting, San Francisco, 

December 3-7, 1990. 

Butler, J.H., I.W. Elkins, B.D. Hall, T.H. Swanson, and T.M. 

Thompson, Measurement of N20 and halocarbons on the third 

Soviet-American Gas and Aerosol Experiment (SAGA ill}, 

presented at a bilateral meeting of U.S. and Soviet scientists al 

NOAA/PMEL, Seattle, WA, August 27-31, 1990. 

Bodhaine, B.A., R.C. Schnell, and P.J. Sheridan, Aerosol instrumentation on the NOAA WP-3D during the third Arctic Gas and 

Aerosol Sampling Program, EOS, 71(43), 1262, 1990. 

Church, T.M., R. Arimoto, L.A. Barrie, F. Dehairs, F. Dulac, T.D. 

Jickells, L. Mart, W.T. Sturges, and W.H. Zoller, The long-range 

atmospheric transport of trace elements: A critical evaluation, in 

The Large Scale Atmospheric Transport of Natural and 

Contaminant Substances, edited by A.H. Knapp and M.S. Kaiser, 

NATO ASI Series, Kluwer, Dordrechl, 321 pp., 1990. 

Conway, T.I., L.P. Steele, P.M. Lang, and L.S. Waterman, The 

NOAA/GMCC carbon dioxide and methane measurements al 

Cape Grim, in Baseline 88, edited by S.R. Wilson and G.P. 

Ayers, 1990. 

Conway, T.J., L.P. Steele, and P.C. Novelli, Measurements of C02 , 

CH4, and CO during AGASP ill, paper presented at the 

American Geophysical Union Fall Meeting, San Francisco, 

Decembcr3-7, 1990. 

Defoor, T.E., I.J. DeLuisi, D.U. Longenecker, and W. Chu, 

Aerosol measurements al Mauna Loa Observatory 1974-1990: 

The normalization and calibration problem, a report presented 

at the Soviet-American Conference on Lidar Intercomparison 

in Obninsk, U .S.S.R., August, 1990. 

DeLuisi, I .I., T.E. DeFoor, D.U. Longenecker, and W. Chu, 

Uncer1ain1ies in the application of lidar for observing 

stratospheric aerosol optical thickness, a poster paper presented 

al the 15th International Laser Radar Conference in Tomsk, 

Siberia, U.S.S.R., August 1990. 

Dutton, E.G., Annual forcing of the surface radiation balance 

diurnal cycle measured from a high tower near Boulder, 

Colorado, J. Climate, 3, 1400-1408, 1990. 

Dutton, E.G., Comments on major volcanic eruptions and climate: A 

critical evaluation, J. Climate, 3, 587-588, 1990. 

Elkins, I ., CFCs and nitrous oxide measurements, paper presented al 

the CSIRO Annual Meeting in Melbourne, Australia, November 

29-30, 1990. 

Elkins, I.W., I.H. Butler, B.D. Hall, T. Swanson, I. Harris, and G. 

Herbert, Measurements of atmospheric halocarbons during SAGA-3: 

analysis of trajectories, meteorology, and comparison with other 

long-lived tracers, EOS, 71(43), 1229, American Geophysical Union 

Fall Meeting, San Francisco, December 3-7, 1990. 

Elkins, I.W., B.D. Hall, and I.H. Butler, Laboratory and field 

investigations of the emissions of nitrous oxide from biomass 

burning, presented at the Chapman Conference on Global 

Biomass Burning: Atmospheric, Climatic and Bioshperic 

Implications, Williamsburg, VA, March 19-23, 1990. 

Elkins, I.W., T.M. Thompson, I .H. Butler, and B.D. Hall, The 

global budget of atmospheric nitrous oxide inferred from 

measurements obtained at NOAA/CMDL stations, in natural 

waters, and during combustion studies, presented al the Seventh 

International Symposium of the Commission on Atmospheric 

Chemistry and Global Pollution (CACGP), Charnrousse, France, 

September 4-11, 1990. 

Hall, B.D., J.W. Elkins, I. I!. Butler, and T.M. Thompson, 

Improvements in nitrous oxide and halocarbon measurements at 

the South Pole, Antarctic J. U.S., 25(5), 1990. 

Harrison, R.M., W.T. Sturges, A.-M.N. Kine, and Y. Li. Kinetics of 

the evaporation of ammonium chloride and ammonium nitrate 

aerosols, Atmos. Environ., 24A, 1883-1888, 1990. 

Herbert, G.A., Secular changes in tropospheric temperatures in the 

northern hemispheric polar region, presented at the International 

Conference on the Role of the Polar Regions in Global Change, 

University of Alaska, Fairbanks, Alaska, June 11 -15, 1990. 

Herbert, G.A., B.J. Stunder, R.C. Schnell, B.A. Bodhaine, and S. J. 

Ohmans, Meteorological conditions during the AGASP-ill 

flights, March 1989, presented at the Fall 1990 American 

Geophysical Union Meeting, San Francisco, December 7, 1990. 

Iickells, T.D., R. Arimoto, L.A. Barrie, T.M. Church, F. Dehairs, F. 

Dulac, L. Mart, W.T. Sturges, and W.I-1. Zoller, The long-range 

atmospheric transport of trace elements: Four case studies, in 

The Large Scale Atmospheric Transport of Natural and 

Contaminant Substances, edited by A.H. Knapp and M.S. Kaiser, 

NATO ASI Series, Kluwer, Dordrecht, 321 pp., 1990. 

Komhyr, W.D., and R.M. Rosson (Eds.}, Climate Monitoring and 

Diagnostics Laboratory, No. 18: Swnmary Report 1989, 141 pp., 

NOAA Climate :vionitoring And Diagnostics Laboratory, 

Boulder, CO, 1990. 

Komhyr, W.D., and R.D. McPelers, Dobson spectropholomeler 83.0 

A standard for ground-based and satellite total ozone measurements, in Digest of Topical Meeting on Optical Remote Sensing 

of the Atmosphere, 1990, 4, 398-401, Optical Society of 

America, Washington, DC, 1990. 

Komhyr, W.D., I.A. Lathrop, and D.P. Opperman, ECC ozonesonde 

and Dobson Umkehr observations during STOIC 1989, in Digest 

of Topical Meeting on Optical Remote Sensing of the Atmosphere, 1990, 4, 441-444, Optical Society of America, 

Washington, DC, 1990. 

Komhyr, W.D., I.A. Lathrop, V.N. Arbuzova, V.U. Khanatov, V.I. 

129 

Pilipenko, and V.V. Radakov, ECC ozonesonde observations al 

Mimy, Antarctica, during 1989, NOAA Data Rep. ERL CMDL-4, 

84 pp., NOAA Climate Monitoring And Diagnostics Laboratory, 

Boulder, CO, 1990. 
Komhyr, W.D., E.A. Crozer, J.A. Lathrop, and M.A. Winey, ECC 

ozonesonde observations at South Pole, Antarctica, during 1989, 

NOAA Data Rep. ERL CMDL-5, 247 pp., NOAA Climate 

Monitoring and Diagnostics Laboratory, Boulder, CO, 1990. 

Komhyr, W.D., SJ. Oltmans, R.D. Grass, and R.K. Leonard, 

Possible influence of long-term sea surface temperature 

anomalies in the tropical Pacific on global ozone, paper 

presented at the Antarctic Ozone Conference, Universidad 

International Menendez Pelayo, Santander, Spain, July 30, 1990. 

Komhyr, W.D .. R.D. Evans, R.D. Grass, G.L. Koenig, J.A. Lathrop, 

and D.M. Quincy, Dobson spectrophotometer, ECC ozonesonde, 

and ground-based NOAA SBUV-2, S/N-2 satellite instrument 

comparison ozone observations, NOAA Data Rep. ERL CMDL-6, 

17 pp., NOAA Climate Monitoring and Diagnostics Laboratory, 

Boulder, CO, 1990. 

Lang, P.M., L.P. Steele, R.C. Martin, and K.A. Masarie, Atmospheric methane data for the period 1983- 1985 from the 

NOAA/GMCC global cooperative flask sampling network, 

NOAA Tech. Memo. ERL CMDL-1, 90 pp., NOAA Climate 

Monitoring and Diagnostics Laboratory, Boulder, CO, 1990. 

Lang, P.M., L.P. Steele, and R.C. Martin, Atmospheric methane 

data for the period 1986-1988 from the NOAA/CMDL global 

cooperative flask sampling network, NOAA Tech. Memo. ERL 

CMDL-2, 108 pp., NOAA Climate Monitoring and Diagnostics 

Laboratory, Boulder, CO, 1990. 

Li, S.-M., J.W. Wincheste r, J.D. Kahl, S.J. Oltmans, R.C. Schnell, 

and P.J. Sheridan, Arctic boundary layer ozone variations 

associated with nitrate, bromine, and meteorology: A case study, 

J. Geophys. Res., 95(Dl3), 22,433-22,440, 1990. 

Lipschultz, F., S. C. Wofsy, B. B. Ward, L. A. Codispoti, G. 

Friedrich, and J. W. Elkins, Bacterial transformations of 

inorganic nitrogen in the oxygen-deficient waters of the Eastem 

Tropical South Pacific Ocean, Deep-Sea Res., 37( 10), 

1513-1541, 1990. 

Montzka, S.A., Oxygenated hydrocarbon measurements in rural 

Alabama, presented at the American Geophysical Union 1990 

Fall Meeting, December 3 -7, 1990, San Francisco, 1990. 

Montzka, S.A., B.M. Hybertson, R.M. Barkley, and R.E. Sievers, 

Low temperature oxidation of YBa2Cu30 6.0 with nitrogen 

dioxide, J . Mater. Res., 6, 891, 199 1. 

Novelli, P.C., J. W. Elkins, and L. P. Steele, Carbon monoxide 

standards for atmospheric measurements., EOS, 71(43),1249, 

American Geophysical Union Fall Meeting, December 3-7, San 

Francisco, 1990. 

Parungo, F., C.T. Nagamoto, P.J. Sheridan, and R.C. Schnell, 

Aerosol characteristics of Arctic haze sampled during AGASPII, Atmos. Environ., 24A, 937-949, 1990. 

Parungo, F., C.N. Nagamoto, P. Sheridan, and R. Schnell, Individual 

particle analysis of aerosol samples collected during AGASP-Ill, 

EOS, 71(43), 1262, 1990. 

Robinson, E., and T.E. Defoor, Recent stratospheric aerosol lidar 

observations at Mauna Loa Observatory, Hawaii, presented at the 

American Geophysical Union Fall Meeting in San Francisco, 

December 3-7, 1990. 

Ryan, S.C., Diurnal C02 exchange and photosynthesis of the Samoa 

tropical forest, Global Biochem. Cycles, 4, 69-84, 1990. 

Ryan, S.C., Diurnal C02 exchange and photosynthesis of the Samoa 

tropical forest, presented at the American Geophysical Union 

Spring Meeting, Baltimore, MD, April, 1990. 

Savoie, D. L., J. M. Prospero, R. Arimoto, R. A. Duce, and B. 

Bodhaine, Concentrations of particulate nitrogen and sulfur 

species and mineral dust in the near-surface atmospheric 

boundary layer over the Pacific Ocean during the GLOBE 

survey flights, paper A4 l C-9 presented at the American 

Geophysical Union Fall Meeting, San Francisco, 

December 3-7, 1990. 

Sheridan, PJ., Analytical electron microscope analysis of aerosol 

sampled over White Sands Missile Range, New Mexico, 

December 11 -15, 1989, Final report to the U.S. Army Atmospheric Sciences Laboratory, NOAA-Cooperative Institute for 

Research in Environmental Sciences, Boulder, CO, 37 pp., 1990. 

Sheridan, P.J., R.C. Schnell, W.H. Zolle r, J.J. Zieman, and R.A. 

Rasmussen, Composition of Br-containing aerosols and gases 

related to boundary layer ozone destruction in the Arctic, EOS, 

71(43), 1265, 1990. 

Sheridan, P.J., R.C. Schnell, and J.F. Boatman, Wintertime black 

carbon aerosol measurements over the southwestern United 

States, December 1989, in Climate Monitoring and Diagnostics 

Laboratory No. 18: Summary Report 1989, edited by W.D. 

Komhyr and R.M. Rosson, pp. 77-80, NOAA Climate Monitoring And Diagnostics Laborato1y, Boulder, CO, 1990. 

Stone, R., E.G. Dutton, and J.J. DeLuisi, Surface radiation and 

temperature variations associated with cloudiness at the South 

Pole, Ant. J . U.S., 24, 230-232, 1990. 

Sturges, W.T. and B.E. Taylor, Atmospheric concentrations of 

chlorinated solvents around a nuclear processing plant in 

Colorado, En viron. Technol., 11, 1063-1070, 1990. 

Sturges, W.T., New insight into chemical reactions of tropospheric 

ozone and bromine at polar sunrise in the Alaskan Arctic, invited 

presentation to Atmospheric Environment Service, Environment 

Canada, Toronto, 1990. 

Sturges, W.T., Bromine and ozone atmospheric chemistry in the 

Arctic, paper presented at the International Conference on the 

Role of the Polar Regions in Global Change, Geophysical 

Institute, University of Alaska at Fairbanks, June 11- 13, 1990. 

Sturges, W.T., R.C. Schnell, S. Landsberger, SJ. Oltmans, J.M. 

Harris, and S.-M. Li, Chemical and meteorological influences on 

surface ozone destruction at Barrow, Alaska, during Spring 1989, 

American Geophysical Union 1990 Fall Meeting , San Francisco, 

1990. 

Sturges, W.T., New insight into chemical reactions of tropospheric 

ozone and bromine at polar sunrise in the Alaskan Arctic, invited 

paper presented to the Air Quality and Monitoring Group of 

Atmospheric Environment Service in Toronto, Canada, on July 

17, 1990. 

Tan s, P.P., K.W. Thoning, W.P. Elliott, and T.J. Conway, Error 

estimates of background atmospheric C02 patterns from weekly 

flask samples,]. Geophys. Res., 95, 14063-14070, 1990. 

Tans, P.P., I.Y. Fung, and T. Takahashi, Observational constraints on 

the global atmospheric C02 budget, Science 247, 1431 -1438, 1990. 

Tans, P.P., The contemporary global carbon cycle from the 

perspective of an atmospheric scientist , presented at the Annual 

Meeting of the American Society of Plant Physiologists, 

Indianapolis, July 29, 1990. 

Tans, P.P., An observational strategy for assessing the role of terrestrial 

ecosystems in the global carbon cycle: scaling down to regional 

levels, presented at the Meeting on Scaling Processes Between Leaf 

and Landscape Levels, Snowbird, UT, December 2-5, 1990. 

130 
ACR 

ADVR 

AEM 

AEROCE 

AES 

AGASP 

AGL 

ALT 

ANL 

ANS TO 

AOML 

AQG 

ARL 

ARM 

ASA 

AS ASP 

ASCII 

ASL 

ATS 

BAO 

BAS 

BSRN 

BRW 

CA DIC 

CAF 

CAMS 

CD-ROM 

CEAREX 

CFC 

CFC-11 

CFC-12 

CI RES 

CMDL 

CN 

CNC 

COR 

CSIRO/DAR 

DB 

DMS 

DNA 

DSIR 

DU 

ECC 

ECD 

EC-GC 

ECMWF 

EKTO 

EML 

ENSO 

EPA 

ERBE 

ERL 

FR LAB 

FSSP 

FfIR 

12. Acronyms and Abbreviations 

active cavity radiometer 

Advanced Very-High-Resolution Radiometer 

analytical electron microscope 

Atmosphere/Ocean Chemistry Experiment 

Atmospheric Environment Service, Canada 

Arctic Gas and Aerosol Sampling Program 

above ground level 

Alert Observatory, Canada 

Argonne National Laboratory 

Australian Nuclear Science and Technology Organization 

Atlantic Oceanographic and Meteorological Laboratory, Miami, Florida (ERL) 

Air Quality Group, Boulder, Colorado (ARL) 

Air Resources Laboratory, Silver Spring, Maryland (ERL) 

Aerosols and Radiation Monitoring Group, Boulder, Colorado (CMDL) 

Antarctic Support Associates, Inc. 

Active Scattering Aerosol Spectrometer Probe 

American Standard Code For W ormation Interchange 

above sea level 

Application Technology Satellite 

Boulder Atmospheric Observatory 

British Antarctic Survey 

Baseline Surface Radition Network 

Barrow Observatory, Barrow, Alaska (CMDL) 

Centro Austral de Investigaciones Cientificas, Argentina 

Clean Air Facility 

Control and Monitoring System 

compact disk/random only memory 

Coordinated Eastern Arctic Experiment 

chlorofluorcarbon 

trichlorofluoromethane 

dichlorodifluoromethane 

Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, Colorado 

Climate Monitoring and Diagnostics Laboratory, Boulder, Colorado (ERL) (formerly GMCC) 

condensation nuclei 

condensation nucleus counter 

correlation coefficient 

Commonwealth Scientific and Industrial Research Organization/Division of Atmospheric Research, 

Australia 

direct-beam [irradiance] 

dimethyl sulfide 

Deoxyribonucleic acid 

Department of Scientific and Industrial Research, New Zealand 

Dobson units 

electrochemical concentration cell 

electron capture detector 

electron capture-gas chromatograph 

European Centre for Medium Range Weather Forecasts 

[a commercial name for a prefabricated building] 

Environmental Measurements Laboratory 

El Nino/Southern Oscillation 

Environmental Protection Agency 

Earth Radiation Budget Experiment 

Environmental Research Laboratories, Boulder, Colorado (NOAA) 

Front Range Lidar, Aircraft, and Balloon experiment 

Forward Scattering Spectrometer Probe 

Fourier transform infrared (spectroscopy) 

131 
GC 

G.E. 

GSFC 

GLOBE 

GRIB 

HP 

HST 

IC 

IR 

ISWS 

ITT 

JPL 

LEAPS 

LORAN 

LST 

LW 

LWD 

LWRF 

MAKS 

MLO 

MLOPEX 

MRI 

MSL 

NADP 

NASA 

NCAR 

NDIR 

NESDIS 

NTP 

NIST 

NMC 

NOAA 

NOAH 

NRBS 

NSF 

NSO 

NWR 

NWS 

OGIST 

PBL 

PC 

PDB 

PESA 

PIXE 

PMEL 

PMOD 

PMT 

PSC 

PSP 

p3 

QBO 

RITS 

RSD 

SAGE 

SASP 

SBUV 

SC 

SEAR EX 

gas chromatograph 

General Electric 

Goddard Space Flight Center 

Global Backscatter Experiment 

"Gridded in Binary" format for ECMWF-TOGA analyses 

Hewlett-Packard 

Hawaii standard time 

ion chromatography 

infrared 

Illinois State Water Survey 

International Telephone and Telegraph 

Jet Propulsion Laboratory 

Low Electron Attachment Potential Species 

LOng Range Aid to Navigation 

local standard time 

longwave 

long wave downward irradiance 

longwave radiative forcing 

Martin and Kitzis Sampler (portable sampler) 

Mauna Loa Observatory, Hawaii (CMDL) 

MLO Photochemical Experiment 

Meteorology Research, Inc. 

mean sea level 

National Atmospheric Deposition Program 

National Aeronautics and Space Administration 

National Center for Atmospheric Research 

non-dispersive infrared analyzer 

National Environmental Satelite, Data and Information Service (NOAA) 

normal incidence pyrheliometer 

National Institute for Standards and Technology (formerly NBS) 

National Meteorological Center 

National Oceanic and Atmospheric Administration 

Nitrous Oxide And Halocarbons Group, Boulder, Colorado (CMDL) 

non-Rayleigh backscatter 

National Science Foundation 

National Solar Observatory 

Niwot Ridge, Colorado 

National Weather Service 

Oregon Graduate Institute of Science and Technlogy 

planetary boundary layer 

personal computer 

pee dee belemnite 

proton elastic scattering analysis 

Proton-Induced X-ray Emission 

Pacific Marine Environmental Laboratory, Seattle, Washington (ERL) 

Physikalisch-Metcorologisches Observatorium Davos [World Radiation Center] 

photomultipicr tube 

Polar stratospheric cloud 

precision sunphotometer 

Portable Pressurizer Pack (air sampler) 

quasi-biennial oscillation 

Radiatively Important Trace Species 

residual standard deviation 

Stratospheric Aerosol and Gas Experiment 

Surface Air Sampling Program 

solar backscattered ultraviolet (satellite ozone instrument) 

sky cover 

Sea-Air Exchange Experiment 

132 
SEASPAN 

SERI 

SIO 

SMO 

SOI 

SO LR AD 

SPO 

SRF 

SRM 

SSL 

SST 

TECO 

TEM 

TOGA 

TOMS 

TSI 

TSL 

TSP 

UCI 

URAS 

URI 

USDA 

USGS 

UT 

UV 

UVB 

WMO 

WPL 

SEAREX South Pacific Aerosol Network 

Solar Energy Research Instirute 

Scripps Instirution of Oceanography 

Samoa Observatory, American Samoa (CMDL) 

Southern Oscillation Index 

Solar Radiation 

South Pole Observatory, Antarctica (CMDL) 

spectral response function 

standard reference material 

slightly stable layer 

sea-surface temperature 

Thermal Electron Company 

transmission electron microscope 

Tropical Ocean Global Atmosphere 

Total Ozone Mapping Spectrometer 

Thermo Systems Incorporated 

Technical Services Laboratory 

total suspended particulate 

University of California, Irvine 

[a commercial co2 analyzer] 

University of Rhode Island 

United States Department of Agriculture 

United States Geological Survey 

universal time 

ultraviolet 

ultraviolet B specLTal band 

World Meteorological Organization 

Wave Propagation Laboratory, Boulder, Colorado (ERL) 

133 U .S GOVERNMENT PRI NTING O<"FICE: 1992-674-362