Geophysical Monitoring 

for Climatic Change 

No. 17 

Summary Report 1988 

U.S. DEPARTMENT 

Of COMMERCE 

NATIONAL 

OCEANIC AND 

ATMOSPHERIC 

ADMINISTRATION 

ENVIRONMENTAL 

RESEARCH 

LABORATORIES 

~I ( • 

• 

• 
Geophysical Monitoring 

for Climatic Change 

No. 17 

Summary Report 1988 

James W. Elkins, Editor 

Rita M. Rosson , Assistant Editor 

Air Resources Laboratory 

Geophysical Monitoring for Climatic Change 

Boulder, Colorado 

December 1989 

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 O. Fletcher, Director 
NOTICE 

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

NOAA Environmental Research Laboratories. Use for publicity or adverlising purposes 

of information from this publication concerning proprietary products or the tests of such 

products is not authorized. 

ACKNOWLEDGMENTS 

The editors appreciate the excellent response from the cooperative programs in contributing to this report. The editors also thank Christine Sweet for her outstanding editorial 

assistance. 

For ~a1c by the N3Lionailechnical Inrorm:lrion Ser\1ce, 5285 Port Royal RO:ld 

Sprin~:rldd. VA 221(.1 

ii 
Contents 

GMCC Slaff, 1988 vii 

GMCC Slation Infonnation ................................................ .............. ......................................................................... viii 

1. 

2. 

3. 

4. 

5. 

Summary .......... .. .................................................................... .......................................................................... . 

Observatory Reports ............................................................................................................................ ... ........ .. 

2. 1. Mauna Loa ............................................................................................................................................ . 

2.2. 

2.1.1. Operations ............................................................................................................................... . 

2. 1.2. Programs ........................................................................................................ .......................... . 

Barrow 

2.2. 1. 

2.2.2. 

Operations .......... ................. .......................... .......................................................................... . 

Programs ........................................... .......... ........................................................................... .. 

2.3. Samoa ........ .................................................................................... ...................................................... .. 

2.3.1. Operations ............................................................... ................................................................ . 

2.3.2. Programs ............................................................ .............. ....................................................... . 

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

2.4. 1. Operations .................................... ........................................................................................... . 

2.4.2. Programs .......................................................................................................................... ....... . 

2.5. References ............................................................................................................................................ .. 

Aerosols and Radiation Monitoring Group ....................................... .............................................................. . 

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

3.1. 1. Surface Aerosols ......... .. ......................................................................................................... .. 

3.1 .2. Solar and Thennal Radiation ........................................................................................... ....... . 

3.1.3. Solar Radiation Facility ........ .................................................................................................. . 

3.1 .4. Turbidity ................................................................................................................................. . 

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

3.2.1 . SPO Aerosol Measurements During 1987 ................................................................................ .. 

3.2.2. Surface Radiation and Temperature Variations Associated With Cloudiness at 

the South Pole ............................................................................................................. .......... . 

3.2.3. Calibration of the SBUV Using Umkehr Measurements .......................................................... .. 

3.3. References ........................................................................ ....... .............................................................. . 

Carbon Cycle Group ........................................................... ............................................................................ .. 

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

4. 1.1. Continuous In-Situ and Flask Sample Carbon Dioxide Measurements .................................. . 

4.1 .2. Flask Sample Methane Measurements ................................................................................... . 

4.1.3. In-Situ Measurements at MLO ........................................................................................... .... . 

4.1.4. In-Situ Methane Measurements at BRW .. .............................................................................. .. 

4.1.5. Flask Sample Carbon Monoxide Measurements ...................................................................... .. 

4. 1.6. In Situ Methane Measurements at MLO ................................................................................ .. 

4.2. Special Projects ..................................................................................................................................... . 

4.2.1. Shipboard Air Sampling: Operation Pacific Air .................................................... ................ .. 

4.2.2. ABLE-3A Mission ................ ..................................................................................................... . 

4.3. References ............................................................................................................ ................................ .. 

Ozone Group .................................................................................................................................................... . 

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

5.1.1. Total Ozone Observations .................................................. .................................................... . 

5.1 .2. Umkehr Observations ...... ............................... ..... .. .................................................................... . 

5. 1.3. Dobson Spectrophotometer Calibrations ................................................................................... . 

iii 

1 

2 

2 

2 

2 

6 

6 

7 

9 

9 

9 

11 

11 

11 

13 

14 

14 

14 

16 

18 

18 

22 

22 

24 

26 

27 

29 

29 

29 

31 

32 

32 

33 

32 

34 

34 

35 

33 

36 

36 

36 

37 

37 
5.1 .4. Validation of TOMS and SBUV Satellite Ozone Data at MLO with 

Dobson Spectrophotometer No. 83 ....................................................................................... 37 

5.1.5. Tropospheric Ozone .................................. ........................ ....... ..... ....... ..... ....................... .......... 38 

5.1.6. Ozonesonde Observations .... .............. ....... ................... .......... .. ... ....... ..... ....... ....... .......... ........... 39 

5.1.7. Stratospheric Water Vapor .............................................................................................. ........... 39 

5.2. Special Projects: Observations Indicating Possible Ozone Destruction During 

the Antarctic Polar Night .... .. . .......................... ........................ ....... ..... ...................... ........... 41 

5.3 References ................................................ ........................... ..................................................................... 42 

6. Acq uisition and Data Management Group ........................................................................................................ 43 

6.1. Continuing Programs .............................................................................................................................. 43 

6. 1.1. Station Climatology .............................................. .................................................................... 43 

6. 1.2. Data Management ...... .......... ............ ......... ............ ....... .......... ....... ....... ..... .. ..... .. ... .......... ..... ...... 48 

6.2. Special Projects: Atmospheric Trajectories .... ....................................................................................... 50 

6.3. References .............................................................................................................................................. 54 

7. Air Quality Group ............................................................................................................................................. 55 

7.1. Continuing Programs ... .......... ......... ............................... ....................................... ....... ........................... 55 

7.1.1. Introduction ............................................................................................................................... 55 

7.1.2. Global Change Expedition and Coordinated Air-Sea Experiment ........................................... 55 

7.1.3. Central U.S. RADM Test and Assessment Intensives .................................................... .......... 55 

7. 1.4. RADM Evaluation Experiment ................................................................................................ 58 

7. 1.5. ACID-MODES Experiment ...................................................................................................... 59 

7.2. Special Projects ...................................................................................................................................... 60 

7.2. 1. SulfurMonitoringatMLO ........................................................................................................ 60 

7.2.2. Blue Ridge Flights ..................................................................................................................... 62 

7.3. References ............................................................................................................................................... 62 

8. Nitruus Oxide and Halocarbons Group ............................................................................................................. 64 

8.1. Continuing Programs ........................ ..................................................................................................... 64 

8.1. 1. Flask Samples ................... ..................................................... ................. ....... ................... ........ 64 

8.1 .2. RITS Continuous Gas Chromatograph Systems at GMCC Base line Stations ......................... 64 

8.1.3. Low Electron Attachment Potential Species ............................................................................ 66 

8.1.4. Gravimetric Standards .......................................... .................................................................... 68 

8.2. Special Projects ....................................................................................................................................... 69 

8.2.1. Soviet-American Gas and Aerosol Experiment II .................................................................... 69 

8.2.2. FT-JR Spectrometer Archive Project .............................................................................. .......... 69 

8.2.3. Airborne Gas Chromatograph ...................................... .............................................................. 70 

8.3. References ................................................ .......................................................................... .................... 70 

9. Director's Office ..... .......... ..................................................................................................... ..... ............ .......... 71 

9.1. Alkaline Aerosols Program: Alkaline Aerosols Inventory . .................................. ....... ............ ....... ........ 7I 

9. 1.1. Introduction ...................................... ......................................................................................... 71 

9.1.2. Method of Estimating Alkaline Dust Prod uction ..................................................................... 71 

9. 1.3. Results .............................................. ......................................................................................... 7 1 

9. 1.4. Comparison With Calcium Wet Deposition Data .................................................................... 72 

9.1.5. Conclusions ............................................................................................................. ................... 73 

9.2. Arctic Gas and Aerosol Sampling Program: Lidar Detection of Leads in Arctic Sea Ice ....................... 73 

9.2.1. Introduction .............................................................................................................................. 73 

9.2.2. Hydrometer Plumes From Open Leads ..................................................................................... 73 

9.2.3. Role of Leads in the Arctic Heat Budget ................................................................................... 75 

9.2.4. Summary and Conclusions ......................................................................................................... 75 

9.2.5. Future Research ....................................................................................................................... . 75 

9.3. References .............................................................................................................................................. 75 

iv 
10. Cooperative Programs ................................. ..................................................................................................... 77 

Precipitation Chemistry 

R. S. Artz ............................................................................ ...................................................... 77 

The Mauna Loa Aerosol Backscatter Intercomparison Experiment (MA BIE) 

David A. Bowdle, Madison J. Post, R. Michael Hardesty, Alltony D. Clarke, 

and Edward M. Pallerson ........................................................................................................... 79 

Fine Particulate Matter at Mauna Loa Observatory March 1988 to February 1989 

T. A. Cahill, L. K. Wilhnson, P. Beveredge, and T. Tanada ...................................................... 82 

Artificial Windshielding of Precipitation Gauges in the Arctic 

George P. Clagell ....................................................................................................................... 85 

UVB Monitoring Data from Mauna Loa and Rockville 

David L. Correll, Carl Clark, Russell Goodrich, and Douglas Hayes....................................... 87 

Status of the Robertson-Berger UVB Monitoring Program, 1974-Present 

Gerald F. Callan.... ....................................... ......... ..................................................................... 89 

The CSIRO Latitudina l Gradient Study of CO2 Isotopes 

Roger Francey, Paul Fraser, and Graeme Pearman ................................................................. 91 

Global Aurora Dynamics Campaign 

K. Hayashi ..... ............................................................................................................................. 94 

The Colorado State University Multiple Field of View Radiometer at the Mauna Loa Observatory 

Paul F. Hein and Stephen K. Cox............................................................................................... 96 

The Global 'He Content of Near-Surface Atmospheric Air 

P. II' Holland and D. E. Emerson............................................... ............................................... 97 

Nitric Acid and Aerosol Nitrate Variations at Mauna Loa 

B. J.I/uebert, C. L. Lee, II' M. Warren, and R. B. Norton ...... .................................................. 98 

Nitrogen Oxide Measurements at Barrow 

Daniel A. Jaffe and Richard E. f/onrath .................................................................................... 100 

Estimates of Uncertainty in Trajectory Ensembles 

.lonathan D. Kahl.................................................. ...................................................................... 102 

Determining Regional Emissions of Aerosol Black Carbon in the Arctic 

JOllathan D. Kahl and A. D. A. Hansen....... ..................................... .............. ............................ 105 

The Global Precipitation Chemistry Project 

William C. Keene, Krystyna Gorzelska, JOInes N. Galloway, Gene E. Likens, 

and John M. Miller ..................................................................................................................... 107 

Stratospheric Trace Gas Measurements at South Pole Station, Antarctica 

J. G. Keys and P. V. Johnston............................................................................................ ......... 109 

Distribution and Mass Balance of Molecular Hydrogen in the Earth's Atmosphere 

M A.K. Khalil and R.A. Rasmussen ....................................................... .. ................................... III 

Radioactiv ity in the Surface Air at BRW, MLO, SMO, and SPO 

Richard Larsen and Colin Sanderson........ ....... .......................................................................... 11 4 

Tropospheric Radiocarbon at Amundsen-Scott South Pole Station, Antarctica from 1972 to 1987 

Lester Machla, Gote Ostlund, and Kirby Hanson ...................................................................... 117 

Seasonal and Latitudinal Trends in the 1 JCI"C Ratio of Methane 

Paul D. Quay, Stagg L. King, D. O. Wi/bur, and J. StU/zman................ .................................... 118 

Measurements of CFC- II, CCI" and CHJCCIJ in Rask Samples Collected at MLO and NWR 

G. C. Rhoderick ................................................................................................ .......................... 120 

The Mauna Loa Observatory Photochemistry Experiment 

B. A. Ridley ................................................................................................................................. 122 

Nitrate and Non-Seasalt Sulfate in Aerosols at American Samoa 

Dennis L. Savoie and Joseph M. Prospero ................................................................................. 124 

Analytical Electron Microscope Studies of Size-Segregated Particles From the Springtime 

Arctic Aerosol 

PatrickJ. Sheridan ..................................................................................................................... 127 

Precipitation Chemistry at MLO: O-Ring Bias 

G. J. Stensland .. ............ .............................................................................................................. 130 

v 
Trends of the Carbon Isotopic Composition of Atmospheric Methane 

C. M. Slevens and A. Engelkemeir. ...................... ....... ..... ....... ................... ..... ..... ............ ........... 131 

Monitoring for Sulfur Dioxide and Total Suspended Particulate at Mauna Loa Observatory 

Henry Yee, Wilfred Ching, and Richard Sasaki .............................................................. ........... 133 

Sampling of Aerosols and Particles at MLO 

William Zoller, Diane Herman, Cai Xing Ying, Denise Conner, Bruce Undenvood, 

and Allan Wll .......................... ........................ ............ .......... ............ ......... .......... ..... ....... ....... .... 134 

II. International Activities, 1988 ........................................................................................................................... 136 

12. Publications and Presentations by GMCC Staff, 1988 ..................................................................................... 138 

13. Acronyms and Abbreviations ...................................... ............................................................... ...................... 140 
Name: 

Latitude: 

Longitude: 

Elevation: 

Time Zone: 

Office Hours: 

Telephone 

Office hours: 

After hours: 

Postal Address: 

Freight Address: 

Name: 

Latitude: 

Longitude: 

Elevation: 

Time Zone: 

Office Hours: 

Telephone: 

Office hours: 

After hours: 

Postal Address: 

GMCC Station Information 

Barrow (BR W) 

71.3233 

156.6067 

Okm 

GMT -9 

8:00 am-5:oo pm 

(907) 852-6500 

(907) 852-6500 

Officer in Charge 

NOANERL/ARL/GMCC 

Pouch 8888 

Barrow, AK 99723 

Samoa (SMO) 

-14.2522 

170.5628 

0.03 km 

GMT-II 

8:00 am-5:00 pm 

011 -(684) 622-7455 

011-(684) 699-9953 

U.S. Dept. of Commerce 

NOAA - GMCC Samoa Observatory 

P.O. Box 2568 

Pago Pago. American Samoa 96799 

vii 

Mauna Loa (MLO) 

19.533 

155.578 

3.4 km 

GMT -10 

8:00 am-5:00 pm 

(808) 961-3788 

(808) 961-3788 

U.S. Dept. of Commerce 

NOAA - Mauna Loa Observatory 

P.O. Box 275 

Hila , Hl 96720 

U.S. Dept. of Commerce 

NOAA - Mauna Loa Observatory 

154 Waianucnuc Ave. 

Hila, HI 96720 

Sout h Pole (SPO) 

-90.000 

0.000 

2.8 km 

GMT +12 

8:00 am-5:oo pm 

Relayed through GMCC Boulder 

Officer in Charge, GMCC Program 

Box 400 USARP 

C/O NA VSUPPFORANT ARCTICA 

FPO San Francisco , CA 96692 

ATTN: South Pole #5-257 
Director'S Office 

lames Peterson. Director 

Bernard Mendonca. Deputy Director 

Ellen Hardman. Secretary 

Antonio Diaz. Guest Scientist 

Dale GlJIette. Physical Scientist 

Jon Kahl. J\TRC Post Doctorate 

Tezz Marquardt, CIRES 

Patrick Reitelbach, Elec tronic Technician 

Riu Rosson, Clerk-Typist 

Pedro Sancho, Guest Scientist 

Russell Schnell, Cm.ES 

Patrick She ridan, NRC Post Doctorate 

Paul Stockton, Physical Science 

Technician 

Denise Theede, Program Clerk 

Thomas Watson, Physical Science Aid 

Chi Zhou, CIRES 

Acquisition and Data Management 

Group 

Gary Herber1, Chief 

Dee Dee Giebelhaus, Secreury 

Richard Clark, Computer Programmer 

Michael Ellis, Physica l Science Aid 

loyce Harris, Computer Specialist 

James McCutcheon, CIRES 

Steve Roughton, Compute r Assistant 

Kenneth Thaut, Electronic Technician 

Aerosols and Radiation Monitoring 

Group 

John DeLuisi, Chief 

Marilyn Van Asche, Secretary 

Christa Anderson, Physical Science Aid 

Bany Bodhaine , Meteorologist 

Michaela Cronin, Physi cal Science Aid 

Ellsworth Dutton, Meteorologist 

Rudy Haas, Mathematician 

Bradley Halter, Meteorologist 

David Kanzer, Physical Science Aid 

Fred Kreiner, Physical Science Aid 

David Longenecker, ORES 

David Massey, Physical Sc ience Aid 

Donald Nelson, Meteorologist 

Timothy Quakenbush, 

Physical Science Aid 

Patrick Reddy, Cm.ES 

Kurt Shallenberger, CIRES 

Michael Shanahan, Physical Science Aid 

Lois Steams, Meteorologist 

Robert Stone, CIRES 

Barbara Thomson, Physical Science Aid 

James Wendell. Electronic Technician 

GMCC Staff, 1988 

Air Quality Group 

Joe Boatman, Chief 

Dee Dee Mitchell, Secretary 

Cynthia Crouch, Cm.ES 

Laureen Guntcr, Meteorologist 

Young Kim, CIRES 

Menachem Luria, NRC Post Doctorate 

lohn Ray, CffiES 

Herman Sievering, CIRES 

Charles Van Valin, Resea rch Chemist 

Dennis Wellman, Engineer 

Stan Wilkison, Computer Programmer 

Carbon Cycle Group 

Pieter Tans, CIRES 

Lee Prendergast, Secretary 

Thomas Conway, Research Chemist 

Ronald Garrell, Physical Science Aid 

Darryl Kaurin, CO-OP 

Duane Kitzis, CIRES 

Patricia Lang, ORES 

Russell Mar1in, CIRES 

Kenneth Manrie, CIRES 

Paul Novelli, CIRES 

Vernon Preston, CO-OP 

L. Paul Steele, CIRES 

John Taylor, CIRES 

Kirk Thoning, CIRES 

lee Wa terman, Research Chemisl 

Ozone Group 

Walter Komhyr, Chief 

Lee Prendergast, Secretary 

Mark Anderson, Physical Science Aid 

Maureen Ballard, ORES 

Brian Bowman, Physical Science Aid 

Sean Coleman, Physica l Science Aid 

Robert Evans, CIRES 

Leigh Fanning, Physical Science Aid 

Paul Franchois, CIRES 

Robert Grass, Physicist 

Timothy Kauffman, Physical Science Aid 

Gloria Koeni g, Computer Programmer 

Jeffrey Lathrop,CO-OP 

Kent Leonard, CIRES 

Michael O'Neill , CO-OP 

Samuel Ohmans, Physicist 

Frank Polacek, m, Meteorological 

Technician 

Dorothy Quincy, CIRES 

LaRae Williams, Physical Science Aid 

viii 

Nitrous Oxide and Halocarbons Group 

James Elkins, Chief 

Marilyn Van Asche. Secretary 

Christina Brunson, CIRES 

James Butler, ClRES 

Ellen De~oney, CIRES 

Keith Egan, CIRES 

Kevin Gurney, CIRES 

Brad Hall, CmES 

Thayne Thompson, Physicist 

Barrow Observatory 

Daniel Endres, Station Chief 

James Wendell, Electronic Technician 

Timothy Quakenbush, Electronic 

Technician 

Mauna Loa Observatory 

Elmer Robinson, Director 

Jud ith Pereira, Program Support 

Technician 

Arne Austring, Physical Scientist 

Lynne Bonnan, Physical Science Aid 

John Chin, Physicist 

Thomas DeFoor, Electronic Engineer 

Thomas Garcia, Meteorologi cal 

Technician 

Rarhara Kerecman. Data Oerk 

Darryl Kuniyuki, NOAA lr. Fellow 

Mamoru Shibau, Electronic Technician 

Alan Yoshinaga, Chemist 

Samoa Observatory 

Steven Ryan. SUtion Chier 

M. Emily Wilson-Godinet. 

Electronic Technician 

South Pole Observatory 

Roben Poston, Lt. j.g.,NOAA Corps 

Ted Mullen. Electroni c Technician 

Elizabeth Cro7..er, Lt., NOAA Corps 

Mark Winey, Elect. Engin ee r 
GEOPHYSICAL MONITORING FOR CLIMATIC CHANGE 

NO. 17 

SUMMARY REPORT 1988 

1. Summary 

At MLO. a highlight of the year was hosting the GMCC 

Annual Meeting on the occasion of the 30th anniversary of CO2 

monitoring at the observatory. A commemorative ceremony 

recognized Prof. C. D. Keeling of SID. who began the program. 

The program still continues with the same analyzer that was put 

into operation in 1958. Additions 10 the MLO program included 

sulfur analyzers, a new CNC counter, and a solar 

spcclroradiometer. Special efforts were made to calibrate the 

World Standard Dobson instrument as part of accelerating 

international interest regarding apparent, long-term global 

decreases of stratospheric ozone. At BRW, we supported a 

major field program, the NASA-sponsored ABLE 3-A, designed 

to explore budgets of trace species in the boundary layer. 

Numerous improvements were made to observatory facilities 

and the large suite of cooperative programs continued with a 

few additions and subtractions. 

Ongoing GMCC core measurement programs included CO2 

and CH4 from the flask network and observatories; total column 

ozone; ozone vertical distribution by ECC sonde and Umkehr 

technique; surface ozone; stratospheric water vapor by baBoon 

soundings at Boulder; CFC-II, CFC-12. and N,O from nask 

samples and observatory analyzers; stratospheric aerosols at 

MLO using Jidar; aerosol light scattering; CN concentration; 

direct and diffuse solar and infrared radiation; meteorological 

variables; and chemistry of precipitation. 

The Aerosols and Radiation Monitoring Group monitoring of 

eN concentration and aerosol light-scattering coefficient shows 

no statistically significant long-term trends. StralOspheric 

aerosols. as indicated by atmospheric solar transmission and 

turbidity data. were near long-term background levels with no 

significant volcanic perturbation. We continued to modestly 

expand our surface radiation budget measurements, especially 

for comparison to similar satellite data. Special aerosol and 

radiation projects were undertaken at SPO to characterize 

conditions there. A new technique was developed to use 

ground.based Dobson-Umkehr UV measurements for compari. 

son to, and direct calibration of, satellite UV sensors for total 

ozone and ozone profile reLrievals. 

The Carbon Cycle Group continued CO2 sampling at the 

observalOries and cooperative sites. The global annual mean for 

1988 was about 2.6 ppm greater than that for 1987, a significantly larger year-to-year increase than in the previous 7 

years (about 1.5 ppm yrl). Several analyses suggested that this 

was a temporary change related to the concurrent ENSO event. 

The globally averaged Linear growth rate of CH4 , May 1983 to 

December 1988, was 12.24 ± 0.08 ppb yr'. The 1988 mean 

global concentration was about 1675 ppb. A program of CO 

monitoring was begun with extensive effort devoted to 

development of a precise analytical system. evaluation of flask 

stability, and preparation of standards. 

The Ozone Group (fonnerly Monitoring Trace Gases) 

continued monitoring of total ozone, Dobson-Umkehr and 

ozonesonde profiles, surface ozone, and stratospheric water 

vapor along with international Dobson calibration work. 

Measurements of surface ozone continue to show intriguing. but 

not fully explained, long-tenn changes. Increases have occurred 

a1 BRW during summer and autumn and at MLO during winter. 

Decreases have occurred at SMa and SPO during austral 

summer months. Oxidation of increasing methane amounts has 

been suggested as a cause for the decreasing ozone. Photolysis 

of methane in the stratosphere has been suggested as a cause of 

the increasing water vapor there. 

The Acquisition and Data Management Group continued 

regular meteorological measurements at the observatories. At 

BRW, SMO, and sPa, annual distribution and frequency of 

hourly average resultant wind direction and speed were quite 

similar to II-year climatologies. The group cooperated with 

many groups to provide air mass trajectories that are so useful 

for interpretatiun of air chemistry measurements. A new 

technique, cluster analysis, was employed to summarize and/or 

explore the sLrUcture of large trajectory data sets. 

The Air Quality Group participated in several field programs; 

most focused on the national acid precipitation program and all 

used the NOAA King Air research aircraft as the primary data 

collection platform. Wide-ranging operations from the western 

Atlantic Ocean to the central United States yielded several 

high.quality data sets and associated publications. 

The Nitrous Oxide and Halocarbons Group continued flask 

sampling of N,D. CFC-II, and CFC-12 as well as quasicontinuous in-situ sampling of NzO, CFC-Il, CFC-12, 

CFC-1I3. CH,CCI,. and CCI,. Growth rates of CFC-II and 

CFC·12, for example, were about 4% per year. Extensive 

laboratory tests were conducted prior to beginning monitoring of 

several very-low-concentration halocarbons--HCFC-22, 

CFC·113. H-1301. and H-1211. The group continued its 

emphasis on preparation and maintenance of the primary gas 

standards required for precise long-tenn monitoring. 

Within the Director's Office research continued on the 

impact of open sources of alkaline substances on the neutralization of some acids and the concurrent effect on the pH of wet 

deposition in the western United States. The AGASP program 

focused on data analysis from AGASP-II (special issues of 

Journal of Atmospheric Chemistry and Atmospheric Environ· 

menJ are forthcoming) and planning for AGASP-ID, to be 

operated out of Norway during March1989. A special effort 

was made this year to obtain contribUlions 10 this volume from 

our cooperating programs. Many scientists responded; their 

contributions constitute Section 10. 
2. Observatory Reports 

2.1. MAUNA LOA 2.1.2. PROGRAMS 

E.ROBINSON 

2.1.1. OPERA nONS 

Two large special research projects were carried out at MLO 

during 1988. First, a major photochemistry experiment, 

MLOPEX, wac; conducted May I-June 4 by NCAR researchers, 

with additional investigators from NOAA/AL and several 

universities. The purpose of MLOPEX was to examine 

photochemical relationships of major odd-nitrogen compounds 

along with some of the odd-hydrogen and odd-oxygen 

compounds, and to obtain data directly applicable to modeling 

remote tropospheric production and loss of 0). Second, a major 

aerosol program, MABIE, was conducted by NASA/MSFC. 

This program was in operation from November 15 to December 

15 and also included investigators from NOAA/WPL and 

several universities. The NOAA/WPL contribution involved the 

operation of a CO2 pulsed Doppler lidar system and included 

several intercomparisons with the MLO ruby lidar. The MABIE 

program is part of NASA's global aerosol backscatter 

experiment to develop design data for a satellite-based laser 

wind sounding system. 

Weekly ozonesonde flights and lidar observations continued 

with the support of NOANNESDIS. The results of these Mill 

observations arc factored into ground-truth calibrations for 

satellite observational systems. Analyses of the MLO 

ozonesonde record, which now includes more than 4 years of 

data, show expected seasonal cycles but, to date, no obvious 

trends in ozone layer characteristics. The 1988 lidar data 

showed that the stratospheric aerosol continued LO decrease, but 

very slowly. This was similar to conditions in 1987, and it 

doubtless reflects the fact that no major volcanic eruptions that 

could have injected aerosol materials into the stratosphere 

occurred during 1988. 

Additions to the GMCC instrumentation at Mill in 1988 

included a pulsed fluorescence S02 analyzer operating in 

parallel with the flame photometric total sulfur analyzer and a 

TSI alcohol-based CNC operating in parallel with the O.E. 

CNC. The original TSI installation was made in May, and it 

became fully operational several months later. It will be 

operated in parallel with the O.E. CNC for about a year, and if it 

proves satisfactory, the venerable G.E. unit will be retired. 

perhaps to the MLO museum. MLO has also assumed 

responsibility for operating the high-precision spectroradiometer 

formerly operated by the University of Arizona. 

Kilauea volcano continued to erupt from a vent 38.4 km 

south of Hilo (64 km east-southeast of MLO) at 250 m. The 

sixth year of this eruption began in January 1988. Volcanic 

plwne haze from this eruption was frequently noticed around the 

island and was the subject of health and other impact 

assessments. At MLO occasional haze events occurred as part 

of the typical midday upslope wind pattern and were identifiable 

by above-background total sulfur and 502 concentrations. 

2 

Table 2.1 lists the major GMCC and cooperative programs 

carried out at MLO in 1988. Comments on some of the 

programs fo1low: 

Carbon Dioxide 

The GMCC Siemens Ultramat-3 IR analyzer and the SlO 

Applied Physics IR analyzer were operated in parallel without 

problems throughout the year. Routine maintenance and 

calibrations were done on both instruments without difficulty. 

The Siemens analyzer has been in operation since August 5. 

1987, and it has proved to be reliable and durable. In April 

1988 the sample line to the Siemans analyzer was changed from 

aluminwn tubing to a Dekabon line, and the inlet was moved 

from 21 m to 40 m, at the top of the tall tower. Preliminary CO2 

average concentration for 1988 at MLO was 350.8 ppm. The 

growth rate was approximately 1.9 ppm yrl . 

The weekly CO2

, CH,. and other-gas sampling programs 

using flasks at MLO and at Cape Kumukahi were carried out 

according to schedule through the year without any special 

problems. 

Outgassing from the volcanic vents at the caldera and along 

the northeast rift zone of Mauna Loa continued to cause some 

observable periodic disturbance of portions of the CO2 data 

record. These erratic record periods were easily identified and 

could be separated from the clean-air record and discarded 

without difficulty. These venting events occurred mostly 

between 0000 and 0800 LST during the nocturnal downslope 

wind regime. i.c .. wind directions betwccn south and southeast. 

The frequency of monthly occurrences of observable outgassing 

from volcanic vents on Mauna Loa are listed in Table 2.2. It 

should be noted that the tabulation in previous annual Summary 

Reporls indicated only the number of days of occurrences and 

not the nwnber or percentage of hours of data that are affected. 

Table 2.2 shows the total time of vent activity. The 1988 annual 

frequency is low, just 2.3% or 199.7 hours. The low percentage 

of observed disturbances in April and December arc likely due 

to changes in volcanic vent. 

Methane 

The methane gas chromatograph was in nonnal operation 

during the year. When the pure-air generator malfunctioned on 

November 8, 1988, it was decided 10 remove this unit and LO 

provide the necessary clean air with cylinder air sent from 

GMCC in Boulder. This change eliminates GC flame-out 

problems when power interruptions occur. 

Nitrous Oxide and flalocarbons 

Operation of the RITS halocarbon GC continued with only 

minor problems. Some modifications to the RlTS GC were 

made in 1988. In November. the system was reconfigured to 

allow colwnn backflushing after each run for the halocarbon. 

An additional 2 Mbytes of memory and a new software upgrade 

were added to the HP computer. 
Gases 

CO, 

Program 

CO"CH, 

CH"CO, CO, 

Surface 0) 

TOlat 0) 

0) prome 

CFC·II,CFC·12, N,o, 

CFC·I I,CFC·12, N,O 

CO" CH,CCI, 

N,o 

Total SufUT gases 

SO, 

Aerosols 

Condensation nuclei 

Optical properties 

Stratospheric aerosols 

Sofar Radiation 

Global irradiance 

Direcl irradiance 

Diffuse irradiance 

Turbidity 

Solar spectroradiometry 

Meteorology 

Air temperature 

Temperature gradient 

Dcwpoint temperature 

Relative humidity 

Pressure 

Wind (speed and direction) 

Precipitation 

Total precipilable water 

TABLE 2.1. Summary of Sampling Programs at MLO in 1988 

Instrument 

Siemens Ultramat-3 IR analyzer* 

3-L glass flasks 

O.S·L glass flasks,lhrough analyzer 

O.S-L glass flasks, p3 

Carle automated GC 

Dasibi ozone mete'" 

Dobson spectrophotometer no. 76 

Dobson spectrophotometer no. 76 

Balloonbome ECC sonde 

300-mL stainless steel flasks 

HP5890 automate..i GC 

Shimadzu automated GC 

CSI flame phOlomclric analyze ... 

TEeD pulsed fluorescence analyze'" 

Pollak CNC 

G,E.CNC· 

TSICNC' 

Four-wavelength nephelometer* 

Lidar 

Eppley pyranometers (3) with Q, 

OG 1, and RGg filters· 

Eppley pymeliomelers (2) with Q 

ruler* 

Sampling Frequency 

Continuous 

1 pair wk-l 

1 pair wk-} 

I pair wk-I 

I sample (24 min)-! 

Continuous 

3 day·1 

2 day·1 

1 wk-i 

1 pair wk-l 

I sample (3 h)·l 

t sample (3 h)·l 

Continuous 

Continuous 

5 wk-} 

Continuous 

Continuous 

Continuous 

1 prome wk-I 

Continuous 

Continuous 

Eppley pymeliomelerwith Q, 001, 3 day-l 

RG2, and RGg filters 

Eppley IKendaU active cavity 1 mo-i 

radiometer 

Eppley pyranometer with shading disk Continuous 

and QftIter* 

J·series sunphotometers, J·202 3 day-l 

and J·314 

Mainz IT sunphotometer MIlO 3 day-! 

PMOD three-wavelength sunphOlometer* Continuous 

Solar spearoradiometer Discrete 

Aspirated thennisto ... Continuous 

Max.-min. thennometers 1 day·' 

Hygrothennograph Continuous 

Aspirated mennistors· Continuous 

Depoint hygromete ... Continuous 

HygrOlhcnnograph Continuous 

Capacitance transduce'" Continuous 

Microbarograph Continuous 

Mecurial barometer 5wk-l 

Bendix Aerovane· Continuous 

Rain gauge, 8-in 5 wk·l 

Rain gauge, 8-in 1 wk·l 

Rain gauge, weighing bucket Continuous 

Rain gauge, tipping bucket· Continuous 

Foskett IR hygromete ... Continuous 

3 

Remarks 

MLO 

MLO and Kumukahi 

MLO 

MLO and Kumukahi 

MLO 

MLO 

Weekdays 

Automated Umkehr method 

From Hilo Airport 

MLO 

MLO 

MLO 

MLO 

MLO; InstaUcd Nov. 

Installed May 

450,550,700,850 run 

694.3 run 

380, 500, 778, 862 nm; 

narrowband; replaced 

Mainz. II in April 

380,412,500,675,862 nm; 

Operational Jan.-April 

380,500,778 run; 

narrowband 

Transfer of U. of Arizona 

program April 1988 

2· and 40-m heights 

Slandard shelter 

MLO and Kulani Mauka 

2- and 40-m heights 

2-m height 

MLO and Kulani Mauka 

NWS calib. 12!1/88 

8.5- and 40-m heights 

KuJani Mauka 

Weekly chart record 
Program 

Precipitation Chemistry 

pH 

Conductivity 

Chemical componenlS 

Cooperative Programs 

CO, (SID) 

CO" DC, N,o (SID) 

Surface S02 (EPA) 

CO2, CO, CH4• i3Cf12C 

(CSIRO) 

CO2, CH4• and other trace 

gases (NCAR) 

Total suspended particles 

(DOE) 

Total 0). S02 

(AES Canada) 

Turbidity 

(AES Canada) 

CH, (DCflle) 

(Univ. of Washington) 

Total suspended particles 

(EPA) 

Uhraviolct radiation 

(Temple Un iv.) 

Uhraviolet radiation 

(Smithsonian) 

Solar au reole intensity 

(CSU) 

Precipitation coUection 

(DOE) 

Prec ipitation collection 

(lSWS) 

Precipitation collection 

(Uni\!. of Virginia) 

Wct-dry deposition 

(lSWS) 

Aerosol chemistry 

(Univ. of Washington) 

Ae rosol chemistry 

(Univ. of Calif.-Davis) 

Aerosol size disuib. and 

chern. (Univ ..... r Hawaii) 

DC (USGS, Denver) 

Various trace gases 

(OGe) 

liNG). Hel vapor, 

and aerosols (URI) 

TABLE 2.1. (continued) 

[nstrument 

pH meter, Hilo lab. 

Conductivity bridge, Hilo lab. 

Ion chromatograph, Hilo lab. 

Applied Physics IR analyzer 

S-L evacuated glass flasks 

Chemical bubbler system 

Pressurized glass flask sample 

Evacuated stainless steel fla sks 

High-volume sampler 

Brewer spectrophotometer, YlK-U; 

Umkehr-automated 

Sonotek sunphotometer no_ 5698 

35-L evacuated flask 

High-volume sampler 

UV radiometer (erythema) 

8-wavelength UV rad iometer 

Multi-apenure tracking photometer 

Exposed collection pails 

Aerochemetric automatic collector 

Aerochemetric automati c collector 

Aerochemetric automatic collector 

Nuclepore filters 

Programmed filte r sampler 

Particle counters 

to-L stainless steel flasks 

Stainless steel flasks 

Filter system 

Sampling Frequency 

Daily 

DaiJy 

Daily 

Continuous 

1 pair wkl 

Every 12 days 

I mo·t 

I pair wk-! 

Continuous 

Continuous 

1-3 day·t 

Every 12 days 

COntinuous 

Continuous 

Continuous 

Continuous 

Continuous 

COntinuous 

Con!inuous 

Continuous 

Integrated 3 day'! 

sample 

Continuous 

Biweekly 

I set wk-I 

(3 flasks) 

Daily 2000-0600 LST 

'"Data from this instrument recorded and processed by CAM:S. 

Remarks 

Rainwater collections, 

3 sites 

Rain water collections, 

3 sites 

Rainwater collections, 

3 sites 

MLO 

MLO and Kumukahi 

24-h (0000-2400) sample 

MLO 

MLO and Kumukahi 

1 ftlter wk-I 

Out of service April 1988 

MLO 

MLO 

24-h (0000-2400) sample 

Integrated radiation responsible 

for su nburn 

290-325 nm, narrowband 

2,5, 10,20,30' fields 

of view 

MLO 

Analysis for 7Be and lOBe 

Organic acid analysis 

NADP 

Upslope-downslope 

discrimination 

1 continuous and 1 down slope 

sample (3 days)-I 

Operated Jan.-April 1988 

MLO 

MLO and Kumukahi 

MLO operational August 1988 

TABLE 2.2. Monthly Occurrences of Outgassing from Volcanic Vents on Mauna Loa 

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

Tot aJlime (hours) 29.0 18.8 24.6 6.5 10.9 12.2 Il.l 27.5 12.2 20.1 10.8 6.0 199.7 

Percent of time 3.9 2.8 3.3 0.9 2.7 1.7 1.5 3.7 1.7 2.7 1.5 0.8 2.3 

4 
Ozone 

As in previous years the ozone program consisted of three 

major components; surface air monitoring using a Dasibi ozone 

monitor, total ozone and Umkehr ozone profiles using Dobson 

techniques, and ozone profiles using balloonbome ECC 

ozonesondes flown from the Hilo NWS station. 

Surface air ozone monitoring was essentially continuous 

lhrough the year. Normal routine calibrations and maintenance 

were carried out regularly. 

Dobson spectrophotometer no. 76, one of the GMCC 

computerized instruments, was in operation throughout the year 

and provided both direct-sun total ozone measurements and 

computer-controlled Umkehr ozone profiles. No prolonged 

downtimes were experienced by the Dobson program. 

Direct-sun Dobson observations were made on observation days 

by the MLO staff whenever weather conditions were favorable. 

During 1988 this amounted to 194 Dobson observation days, or 

80% of the total 243 possible days of observation. During the 

1988 summer the WMO World Standard Dobson instnunent no. 

83 was again calibrated by the Langley plot method, using a 

series of measurements at MLO. Also at this time intercomparison calibrations were carried out between no. 83 and MLO 

Dobson no. 76 and SMO Dobson no. 42. These special 

observations continued the pattern of frequent standardizations 

and intercomparisons of the GMCC Dobson instruments as well 

as the WMO World Standard no. 83. 

The 1988 ozonesonde operations consisted of 51 total 

instrument launches; of Lhese, 44, or 86%, resulted in usable 

ozone profiles. Of the seven unproductive launches. instnunent 

failure after launch and in mid-flight was the most common 

problem. The 44 successful flights consisted of 42 using the 

large 40·km plastic balloon and 2 using 2,OOO'g rubber balloons. 

The 42 plastic balloons rose to an average altitude of 41.2-km, 

and all but 2 exceeded the target altitude of 40 km. Both of the 

2,OOO'g rubber baUoon nights in 1988 exceeded 35 Ion altitude. 

The 1988 results are similar to those of 1987 [Bodhaine and 

Rosson, 1988], when all but 3 of 48 successful flights exceeded 

40 km and the average altitude of rise was 4 1.4 km. 

Sulfur Gases 

A CSI flame-photomerric total sulfur analyzer (i.e., S02 plus 

other sulfur gases) has been in operation since the latter part of 

1987. The instrument is calibrated manually once per week. 

During November 1988 a TECO pulsed fluorescence S02 

monitoring instrument was added to the system and set up to 

sample in parallel with the CSI flame photometric unit. These 

two instruments are on loan to MLO from the GMCC Air 

Quality Group. Both systems operated without problems. The 

pulsed fluorescence instnunent is programmed to have an 

automatic, once-daily, calibration cycle. The TECO instrument 

is sensitive specifically to S02 with a detection limit of 

approximately 0.05 ppbv . The CSI flame-photometric unit has a 

higher detection limit of about 0.5 ppbv, and it is sensitive to the 

total atmospheric gaseous sulfur concentration, detecting 

various sulfur compounds, such as CS2 and OCS, in addition to 

S02' The results from these two sulfur gas analysis systems 

operated at MLO are summarized in Section 7 of this Summary 

Report. 

5 

Aerosols 

The MLO aerosol program was augmented in May with the 

addition of a TSI CNC. The TSI is a continuous expansion-type 

CNC in which the condensing vapor is isopropyl alcohol instead 

of the water used in the pulsation expansion G.E. CNC. The 

TSI system became fully operational in the fall and has operated 

reliably since then. After a period of about a year of consistent 

operation in parallel with the G.E. CNC, it is expected that the 

old G.E. CNC system can be retired. The PoUak CNC 

continued to provide daily standard CN concentrations that were 

used to calibrate both the old O.E. and the new TSI CNC 

instruments. 

Monitoring of stratospheric aerosol layers was carried out 

lhrough periodic lidar observations. Figure 2.1 shows the 

integrated non-Rayleigh backscatter values for the MLO lidar 

observations between 16 and 33 km for the period 1985· 1988. 

During 1988 a total of 37 lidar observations of stratospheric 

aerosol profiles were obtained. Whenever possible these lidar 

observations were coordinated with an overpass of the SAGE-ll 

satellite. It was possible to implement a number of the lidar 

improvements that are part of the ongoing lidar upgrade 

program. An interim chassis was assembled to operate the laser 

in the planned horizontal position, and to increase the separation 

of the telescope and the laser aperture; the required vertical 

beam was obtained through the use of a 90· beam-bender 

coupled with a collimator. A I5-cm by 1.6-cm ruby laser rod 

was also installed in place of the older 7.6-cm rod. Other 

planned modifications to the lidar cannot be implemented until 

major modifications to the lidar building can be done. No 

significant srralOspherlc aerosol injecliuns WI;!TC delecled in 

1988. As shown by Figure 2.1, the average non-Rayleigh 

backscatter continued to decrease in a more-Of-less linear 

fashion, averaging about 25% yrl during 1987 and 1988. 

Solar Radiation 

The major change in the solar radiation program in 1988 was 

the assumption by the MLO staff of the program of solar 

spectroradiometry, which previously had been under develop45 

ir 

z 4.0 

e 3.5 

~ 

tt 3.0 

o 

~ 2.5 

m 

~ 2.0 

o 1.5 

« 

'" <!J ~.O 

"' ~ 

~0.5 

1985 1986 1987 '1988 

I , "A "i,i,i"i.ioi.i,I,.,i"."i .. i,.,i""'D'.i,I,.,."i .. i"i,.,i"i. .i""I "'I;'I~ " r , " •• " • 

Fig. 2. 1. Non-Rayleigh backscatter coefficient values, 1985-1988, for 

MLO lidar obseIVations belween 16 and 33 km. 
ment by the University of Arizona through the support of a 

NOAA research grant. The objective of this program is to carry 

out a long-tenn program of solar spectroradiometry of sufficient 

precision and accuracy to track changes in the solar "constant." 

Considerable additional engineering of the system has been 

carried out. Turbidity measurements were again being made 

with the older J-series sunphotometers when in April the newer 

Mainz II unit no. M 120 failed and had to be returned to the 

factory. The other components of the MLO solar radiation 

program were continued with little change from prior years. 

These are listed in Table 2.1. 

Meleorofogy 

The meteorological measurement program was accomplished 

without major problems during the year. In February the wind 

speed and direction systems were calibrated. The MLO mercury 

barometer was calibrated by NWS in December, and a new table 

of barometer correction factors was calculated. The mercury 

barometer is read daily and used to establish the calibration 

factor for the CAMS continuously recording pressure sensor. 

Precipifaliol1 Chemislry 

The precipitation chemistry program consisted of a 

combination of NOANARL and cooperative programs. The 

NOANARL program included collections 5 days per week 

from three sites: Hilo, 35 km on Saddle Road, and at MLO. 

The collected precipitation from these sites as well as rain 

and/or snow samples from SMO, BRW, and SPO were analyzed 

in the MLO Hilo chemistry laboratory. 

Cooperalive Programs 

The SIO CO2 monitoring program marked 30 years of 

continuous operation at MLO. This anniversary was the 

occasion for holding the 1988 GMCC Annual Meeting in Hilo. 

A commemorative ceremony was also held at MLO to mark this 

special event on March 28, 1988, exactly 30 years from the day 

on which the rust meaningful data were generated by SIO's CO2 

analyzer. The commemoration was opened by a typical 

Hawaiian blcssing suited to the occasion and then a presentation 

of certificates of recognition to Dr. C.D. Keeling of SIO and 

GMCC researchers. The SIO program of CO2 monitoring at 

MLO is continuing with the same Applied Physics IR CO2 

analyzer that was put into operation in March 1958. 

Three new cooperative programs were begun in 1988, an 

aerosol sampling studies. Two of the programs are continuing. 

One of these, which is being operated for the Crocker Nuclear 

Laboratory, University of California at Davis, collects a weekly 

set of two 3-day integrated filter samples; one is collected 

continuously and one is collected only during expected 

downslope wind conditions (i.e., 2000 to 0600 LST). This 

program is part of a nationwide background aerosol program 

related to the evaluation of visibility in remote, unpolluted 

locations. The second new and continuing aerosol sampling 

program begun in 1988 is an expansion of the periodic fi l~er 

sampling done previously by URI, School of Oceanography, on 

a quarterly basis. The expansion involves weekJy filter changes 

by MLO staff of a batch of daily filters. One filter is exposed 

daily during the period of expected downslope winds, 

6 

2000-0600 LST, at the 23·m level of the tall tower. URI 

analyzes these filters for HNO), HCl, and other related 

constituents. The third new aerosol study carried out by the 

University of Hawaii was relatively short lived, January lhrough 

April. It combined particle size distribution measurements with 

a controlled heating cycle to infer both particle size and 

chemica1 composition. 

In April 1988, the Brewer MKII ozone spectrophotometer of 

Atmospheric Environment Service, Canada, was damaged by 

power surges caused by nearby lightning strikes, and it had to be 

returned to Canada. The program had not been resumed by 

year's end. 

Table 2.1 lists the 22 cooperative program experiments 

operated by 17 different institutions at MLO. In each program, 

MLO staff members may take specific samples (e.g., nasks or 

filters) or monitor the continuously operating sampling 

instruments; however, in all cases, the output of the experinlent 

is returned to the P.1. for analysis and data interpretation. A 

number of these programs are described by the P. I. 's in short 

summary reports that arc included in Section 10 of this 

Summary Report. In addition to the programs listed in Table 

2.1, there were a number of cases during 1988 when ind ividual 

investigators came to M LO to carry out discrete, short-period 

studies in which MLO staff members did not become directly 

involved; these short-period studies by visiting P.I. 's are not 

listed. Two of the more extensive programs, the NCAR 

MLOPEX and the NASA MABIE, were mentioned previously. 

2.2. BARROW 

D. E~DRES 

2.2.1. OPERATIOKS 

The GMCC operation at BRW completed another successful 

year of data collection in 1988. The academic and scientific 

community's increased interest in Arctic science continued. 

BRW had a supporting role for a host of visitors. Among the 

visitors to the station were the NOAA Administrator and the 

Vicc Chancellor for Research and Dean of the Graduate School 

at the University of Alaska, Fairbanks. In March BRW 

personnel had a key role in helping to establish contacts and 

logistic ground support between NASA and the North Slope 

Borough for the ABLE-3A flights over the Arctic in july. In 

July BRW hosted special projects for ABLE-3A, and its 

long-tenn data were incorporated as ground truth for the NASA 

ABLE-3A flights. During March there was a personnel change 

when the electronics technician took a position in Boulder. 

During the summer months a new program was started in which 

the BRW personnel assisted in the training of the new SPO 

crew. Training went well and it is expected that the program 

will continue into the future. An ongoing rela tionship in which 

the observatory and its personnel are called on by the North 

Slope Borough for technical information and expertise 

continued in 1988. As part of this exposure, GMCC personnel 

were featured in severa] media articles ranging rrom radio 

interviews to magazine articles to public television interviews. 
Work was done on both vehicles by GMCC personnel. DEW 

Line personnel were often too busy with their own vehicles to 

offer assistance. Because of the endless difficulty involved with 

securing a local mechanic, it was decided it would be easier to 

have GMCC personnel do vehicle repairs when possible. 'This 

included doing the routine oil changes and rune-ups, replacing 

the engine and transmission in the GMC pickup truck, and doing 

a complete brake job. 

To remedy poor telephone performance, several splices were 

cleaned and retaped in the phone line to the observatory in 

hopes that it would solve the noise problems. It was decided 

that this was not the answer and that new lines would be nceded. 

Negotiations were undertaken by USGS in Fairbanks on 

GMCC's behalf. 11 is expected that the new lines will be 

installed within a year. 

Air conditioning was installed because of severe overheating 

problems due in part to the number of instruments with heaters 

at the station. The temperature was found to be over 28"C on 

several occasions. The air conditioner also helped with the 

static problem due to Jack of humidity in the station. 

A major change in housing occurred when NWS decided that 

it would best serve its interests if GMCC were to give up the 

half of the duplex it occupied and be given complete control of 

the double-wide modular house. By October plans were drawn 

up by tlle BRW staff to remodel the double-wide house into a 

duplex. The BRW staff did the construction. and by the end of 

the year were well on the way to having half of the house done. 

The clean room in the observatory was reorganized in an 

altempt to make more room for new projects. Power is the main 

concern for future expansion. Some circuits are pulling the 

maximum rated load, and any further expansion is impossible. 

In the CAMS ooits, all AID boards were adjusted. A new I/O 

card was installed when an old one failed . A new LED was 

installed because an old one burned out and caused several tape 

drive errors. Updated versions of the data collection programs 

were also installed over the course of the year. 

2.2.2. PROGRAMS 

Table 2.3 summarizes the measurement programs at BRW; 

operational highlights are as follows: 

Carbon Dioxide 

The bearings in the chopper motor of the URAS-2T analyzer 

seized. and the motor was replaced. New regulators were 

installed to replace the aging ones. The old regulators were 

becoming harder to adjust, and replacement-parts cost was 

prohibitive. 

Flask sampling was routine for the entire year. 

Methane 

The CH4 GC underwent a major upgrade in early July. A 

new data acquisition system and new hardware for sample 

selection was installed. New sample lines that run up to the top 

of the meteorology tower were also put in at that time. They 

replace the lines that ran to the rail along the top of the 

observatory building. The system continued to operate without 

incident a11 year. 

7 

Surface Ozone 

A new Dasibi meter was installed when a power surge 

overloaded the power supply and caused erratic performance in 

the old unit. 

Total Ozone 

The Dobson spectrophotometer operated well most of the 

year. The only problem was a clock drive for the pen, which 

quit late in the year. 

OZOn/! Profiles 

Balloons were launched on a cut-back schedule this year. 

Instead of one launch per week, one was scheduled every 2 

weeks. 

Nitrous Oxide and Halocarbons 

Several minor operational upgrades were made by station 

personnel. New versions of the data acquisition program were 

installed on two different occasions. and minor repairs were 

made on the exhaust plumbing to the HP GC. NOAH personnel 

visited the site twice for routine maintenance and upgrades. 

Aerosols 

An aethelometer was installed in March to measure black 

carbon. A high correlation has been seen between black carron. 

CO2, and CH4 values. The aethalometer ran well all year and 

gave good data. Filters can also be analyzed at a late .. date for 

carbon content. 

The nephelometer blower was dismantled. and all gears anrl 

bearing surfaces were cleaned and lubricated after channel 4 

kept dropping out. The grease in the drive gears was dried UP. 

causing the valve to drag and not tum to the correct position. 

After the cleaning. the nephelometer ran rme except for a blown 

fuse. 

The G .E. CNC underwent the nonnal maintenance proce· 

dures and ran well all year. 

Solar Radiation 

There were no unusual occurrences, and all instruments ran 

fine. During the Arctic night, instruments were sent to Boulder 

for calibration. 

Meteorology 

Several record highs and several record lows were recorded 

this year. A new hygrothennometer that was installed in 

September to replace the old unit that quit earlier in the year ran 

fine the rest of 1988. 

Precipitation 

Samples were collected as available. They were sent to 

MLO for analysis of pH and conductivity. 

Cooperative Programs 

Fifteen cooperative programs were hosted at BRW during 

1988. Operational highlights are listed here, and a complete 

listing of the cooperative programs is included in Table 2.3. 

This arrangement between GMCC and outside researchers is a 

continuing program that maximizes the talents, expertise, and 
TABLE 2.3. Summary of Sampling Programs at BRW in 1988 

Program 

Gases 

CO, 

CO"CH"CO 

CII" CO, CO, 

Surface 0) 

Total 0) 

0) prof tie 

CrC-I I, CrC-12, N,O 

CFC-II. CFC-12. N20, 

CCI4 , CI-I)CQ) 

NzO 

Aerosols 

Condensation nuclei 

Optical properties 

Black carbon 

Sofar and Terrres/riBl RadiB,ion 

Albedo 

Global irradiance 

Direct irradiance 

Terrcstrial (IR) radiation 

Turbidity 

Meteor%RY 

Air temperature 

Dcwpoint temperature 

Pressure 

Wind (speed and direction) 

Precipitation 

Precipitalion Chemistry 

pH 

Conductivity 

Cooperalivt Programs 

Total surface particulates (DOE) 

Aerosol chemistry (URI) 

Aerosol chemistry (Univ. of Alaska) 

Precipitation gauge (ASCS) 

Magnctic fields (USGS) 

"c (USGS) 

Various trace gases (OGC) 

CO2

, CH4 and other trace gases (NCAR) 

"C, ''0, CO, (CSIRO) 

CO" "c, N,O (SIO) 

Halocarbon monitoring (Univ. of 

Calif., Irvine) 

Earthquake detection 

(Univ. of Alaska) 

'3CH4 ('Jc/''2(:) (Univ. of Washington) 

NO .... NOy (Univ. of Alaska) 

Uhralow frequency waves (Univ. of Tokyo) 

Inslrument 

URAS-2T IR analyzer 

3-L glass flasks 

O.S-L glass flasks, through analyzer 

O.S-L glass flasks, pl 

Carle automated GC 

Dasibi ozone meter 

Dobson spectrophotometer no. 91 

BaUoonbome ECC sonde 

300-mL stainless steel flasks 

HPS890 automated GC 

Shimadw automated GC 

Pollak CNC 

G.E. C1\C 

Four-wavelength nephelometer 

Aethelometer 

Eppley pyranometer and pyrgeometer 

Eppley pyranometers with Q and RG8 ftiters 

Tracking N1P 

Eppley pymeliometer with Q, OG I, 

RG2, and RG8 fillers 

Eppley pyrgeometer 

Sunphotometers with 380-, 500·, Tl8-, 

and 862-nm narrowband filters 

Thennislor, 2 levels 

Max.-min. thennometers 

Dewpoint hygrometer 

Capacitance transducer 

Mercurial barometer 

Bendix Aerovane 

Rain gauge, tipping bucket 

pH meter (samples analyzed at MLO) 

Conductivity bridge (samples analyzed al MLO) 

High-volume sampler (I filter wk·t) 

High-volume sampler (2 filters wk") 

High-volume ftlters (3 filters wk-') 

Wyoming shielded precipitation gauge 

Magnelomcter 

to-L stainless steel flasks 

Stainless steel nasks 

3-L stainless steel flasks 

5-L glass nasks 

S-L evacuated glass flasks 

Various Slainl css steel flasks 

Seismograph 

35-L sta inless steel flasks 

Chemiluminscence 

Magnetometer 

8 

Sampling Frequency 

Continuous 

I pair wk-' 

I pair wk-) 

1 pair wk-) 

I sample (24 min)-l 

CoOlinuous 

3 day·l 

2mo-1 

I pair wk-' 

I sample (3 h)-' 

I sample (3 h)" 

I day" 

Continuous 

Continuous 

Continuous 

Continuous 

Continuous 

Conlinuous 

Discrete 

Continuous 

Discrete 

Continuous 

t day-I 

Continuous 

Continuous 

Discrete 

Continuous 

Discrete 

2mo-l 

Continuous 

Continuous 

Continuous 

2 mo') 

I station check wk-! 

1 pair mo-i 

1 set wk') (3 nasks serl) 

1 pair wk-I 

I pair (2 wk)"' 

1 pair wk-! 

1 set (3 mo)·1 

Continuous; 

check site 1 wk-', 

change tape I mo') 

I (2 wk)'t 

Continuous during 

the summer 

Continuous 
instrumentation of both groups to engage in research efforts at a 

remote site. All projects are related and complementary to the 

general GMCC research mission. 

A system to measure NO" and Nay was set up and run during 

the summer. Il is expected Lhat it will be used again during the 

next spring Arctic haze episode. 

The sample hose for the URI filter sampler was cracked and 

was patched temporarily. URI was notified, and a new hose was 

ordered. The new hose was received and installed in November. 

A filter sample project for Lhe University of Alaska, 

Fairbanks, was terminated. Il had been running for about 2 

years. 

A new rain gauge was set up this summer and the old one 

pulled down by USDA Soil Conservation Service/Snow Survey. 

The old gauge had deteriorated because of the weather. 

The University of Tokyo had a recorder installed to measure 

ultralow-frequency waves. This is part of a USGS project to 

examine geomagnetics. 

A new pump was required for the DOE filter sampler. A 

power outage caused the old pump to lock up, and it could not 

be restarted. 

2.3. SAMOA 

S.RYAN 

2.3 .1. QPERAllO"S 

SMO facilities operated well in 1988. Some upgrades were 

completed in the housing units; GMCC housing unit T-I I had a 

patio extension, a two-car carport, and an outdoor storage area 

constructed. A new refrigerator was installed, and some minor 

interior remodeling was pcrfonned. 

At the observatory the main air conditioner was repaired in 

May, two new batteries were installed in the photovoltaic 

system, the EKTO UPS was repaired after a 4-mo down time, 

and the Dobson dome was repainted. Both vehicles performed 

well. The Toyota pickup LrUck had a rusted frame member 

replaced in September. 

On February 28, Chief Va'a luli died in an automobile 

accident in California. He was buried alongside his brother and 

sister in the family plot on the lower observatory road on March 

5. The monthly lease checks have been put into an escrow 

account pending the naming of the next luli title holder. 

Utility power problems began anew with several severe 

power surges in May. Power outages increased at year's end. 

In December the observatory was without utility power for a 

total of 24 hours. 

2.3.2. PROGRAMS 

Table 2.4 summarizes the programs at SMa for 1988. 

Further discussion of some of the programs follows. 

Carbon Dioxide 

The system was converted from a single sampling line to 

dual sampling lines that are each sampled for 25 minutes each 

9 

hour. The new configuration required installation of a new 

plumbing/switching apparatus, revised CAMS software, 

additional fTeezer traps, refrigerator cooling plumbing, and a 

second sampling line from Matatula Point. Conversion was 

completed by September. 

A new Cincinnati subzero cooler was installed in February. 

It failed in May and had to be replaced by a Cryocool unit. In 

December, the chopper motor assembly in the URAS analyzer 

had to be replaced. 

Surface Ozone 

Observations continued in 1988 with Dasibi ozone meter no. 

1323. 

Tola/ Ozone 

In January, a desiccant drying system with a low-volume 

positive pressure pump was installed. After tests were 

perfonned, which showed this device 10 be ineffective, a higher 

volume recirculation system was installed in July, which has 

given good results. A four-observations-pcr-day schedule was 

continued throughout 1988. 

Ozone Profiles 

A cutback in supply shipments to Samoa reduced the number 

of ozonesonde flights this year. A total of 37 launches were 

made, and 31 (84%) provided good data. In January, two 

members of the Trace Gases Group visited 10 conduct a series of 

stratospheric water vapor balloon launches. 

Nilrous Oxide and lIalocarbolls 

Now into its third year, lhe RITS GC continued automated 

operations. Some modifications were made in 1988. In 

January, two bakeouts and an Hz ECD conditioning were 

perfonned. Software was upgraded three times during the year, 

and the troublesome HP Thinkjet printer was replaced by an 

Epson in July. Several weeks of CFC·ll daLa were lost in 

October because of a low ambient air now rate. In November, 

the system was reconfigured to allow column backfiushing after 

each run for the halocarbons, 2 Mbytes of additional memory 

were added to the HP computer, and new batteries were ordered 

for the UPS. 

Flask sampling continued on a weekly basis. 

Aerosols 

The four-wavelength nephelometer operated well throughout 

the year; occasional problems were solved by board swapping or 

spider removal. In March, the G.E. CNC counter calibration 

offset voltage was lowered to its minimum selling to reduce a 

high backgrOlUld problem. The instrument performed well in 

this mode lhroughout the rest of the year. 

Solar Radialion 

A new terminal box and cabling to the rooftop pyranometers 

was installed in May, and the tracking pyrheliometer was 

exchanged with a fresh1y calibrated unit from Boulder. A 

sunphotometer had to be replaced because of a faulty memory 

chip. 
Program 

Surface 0) 

Total 0) 

0) profile 

CFC·II. CFC·12, N,O 

eFe-It, CFC-12. N20, C04• 

CI-I)CO) 

N,O 

Aerosols 

Condensation nuclei 

Optical properties 

Sofar Radiation 

Global irradiance 

Direct irrndlance 

Turbidity 

Meteorology 

Air temperature 

Pressure 

Wind (speed and direction) 

Precipitation 

Precipitation Chemistry 

pH 

Conductivity 

Cooperative Programs 

CO,. "C, N,O (SIO) 

GAGE projcc" CFC·II, CFC·12, 

N,O, CH,CO" CO, (OGC) 

Various trace gases (OGC) 

''C, "0, CO, (CSIRO) 

''C (USGS) 

Wet-dry deposition (J\ADP) 

Bulk deposition (EML) 

Hi-vol sampler (EML) 

I-li-vol sampler (SEASPAN Project) 

CO2, C1-I4 • trace gases (NCAR) 

13e, i3CH4 (Argonne Lab.) 

4He (U.S. Bureau of Mines) 

TABLE 2.4. Summary of Sampling Programs at SMO in 1988 

Instrument 

URAS-2T IR analyzer 

3-L gla ss flasks 

O.S-L glass flasks, through analyzer 

O.S-L glass flasks, p3 

Dasibi ozone meter 

Dobson spectrophotometer no. 42 or 65 

Balloonbome 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 RGg ftlters 

Eppley pyranometers with Q Wters on tilted mounts 

Eppley pyrheliometcr with Q ftlter 

Eppley pyrheliometer with Q. OGI, 

RG2, and RG8 fLlters 

Sunphotomelers with 380-, 500-, 178-, 

and 862-nm narrowband ftlters 

ThennislOrs (2) 

MM.-min. thennometcrs 

Capacitance transducer 

Microbarograph 

Mercurial barometer 

Bendix Aerovane 

Rain gauge, weighing bucket 

Rain guage, lipping bucket 

Rain guage, plaslic bulk 

Aerochem wct/dry collector 

Fisher model 805 meter 

Beckman model RC-l6C meter 

5-L evacuated glass fla sks 

HP5880 gas chromatograph 

Stainless steel flasks 

SOl glass flasks 

IO-L stainless sleel fla sks 

HASL Chemctrics wet-dry collector 

Plastic bucket 

High-volume sampler 

High-volume sampler 

Evacuated stainless steel flasks 

30-L evacuated steel cylinders 

I-L pressurized steel cylinder 

10 

Sampling Frequency 

Continuous 

I pair wk-· 

I pair wk-l 

2 pair wk-t 

Continuous 

4 day-. 

I wk-t 

1 pair wk-' 

1 sample (3 h)-t 

I sample (3 h)-' 

1 day-l 

Continuous 

Continuous 

Continuous 

Continuous 

Continuous 

Discrete 

Discrete 

Continuous 

I day-l 

Continuous 

Discrete 

1 wk-' 

Continuous 

Continuous 

Continuous 

I day'\ 

I day-l 

I day" (GMCC); 

I wk" (NADP) 

I day" (GMCC); 

I wk" (NADP) 

3 flasks wk-' 

I hoi 

3 flasks wk·l 

(3 flasks set-I) 

I pair moot 

2 pairmo-I 

1 wk", wet; 

discrete, dry 

Continuous (1 bucket mo-I ) 

Continuous (I filler wk-!) 

Continuous (1 filler wk-t) 

1 pair wk-! 

1 pair discrete 

2yrt 
Meteorology 

The meteorology program continued with the same instruments as in 1987. In July 1988, a period of 11 consecutive 

months of below-normal precipitation finally ended. December 

1988 was the rainiest month in the 12-year Samoa record. 

Precipitation Chemislry 

In March the funnel/bottle collector was replaced with an 

Aerochem wet/dry collector. Following this change, rain 

samples had much lower average conductivities and the average 

pH rose from 4.8 to 5.2. 

Cooperative Programs 

The complement of cooperative programs conducted at 

Samoa remained unchanged in 1988. 

The largest cooperative project at SMO is OGC's GAGE gas 

chromatography program. A new PC for data acquisition was 

insta1led in February, and it experienced some downtime from 

lhe utility power problems later in the year. A replacement 

terminal was installed on the HP5880 chromatograph in May. 

The DOE/EML high-volume pump was replaced late in 1988 

with a new unit. Filter collection continued on an uninterrupted 

basis a11 year. 

2.4. Soum POLE 

R. POSTON 

2.4.1. QPERAllONS 

SPO is operated in cooperation with NSF at the AmundsenScott South Pole Station. Located on the Polar Plateau at an 

elevation greater than 2.8 km above sea level and only 150 m 

from the geographic South Pole. GMCC's CAF samples what is 

probably the cleanest and most constant air mass on earth. Because of the 6-mo long day and 6-mo long night, the air shows 

no signs of diuma1 variations in its constituents, and except for 

total ozone, only slight indications of seasona1 variations. 

Transportation of supplies and personnel to and from the 

South Pole is provided by the U.S. Na"y Operation Deep Freeze 

YXE-6 squadron, which uses ski-equipped LC-130 Hercules 

aircraft for its polar operations. Because of the intense cold, the 

aircraft operations can only be maintained during the austral 

summer, approximately late October through mid February. As 

a training mission, the U.S. Air Force provides a mid-winter 

airdrop of materia1s. fresh food, and personal mail to the crew of 

approximately 20 winter-over personnel who otherwise spend 

8.5 months of the year in seclusion from the rest of the world. 

The GMCC program. staffed by a two-person crew. is only one 

of several programs operating continuously at the South Pole. 

The raising of the CAF last year has proved to be helpful in 

the constant baltle against drifting snow accumulation around 

the building. The drifting and blowing snow is now far less 

impeded by the building's presence, and although there is still 

some accumulation of snow downwind of the building, most of 

the accumulation is now 5-10 m downwind, and not right next 

to the building. Also, although there is a net buildup of snow 

directly underneath the building. occasional shifts in wind 

II 

direction actually scour this area somewhat. thus significantly 

slowing the accumulation there. 

A new steel deck and stairway were installed in January and 

February. The deck provides storage space for crates of air 

sample flasks, calibration gas cylinders, and empty crates and 

boxes. These items had previously been stored on the roof. 

inside the building, or in the cargo storage area 0.4 km away. 

The lower section of stairway was originally intended to be 

raised when not in use and lowered as needed, but the counterbalance provided was not the correct weight. The stairs had to 

therefore be made fixed, instead. The upper section of stairway 

goes from the CAF main level to the roof. where an increasing 

number of experiments and apparatus are located. 

Lack of good, clean power was responsible for some loss of 

data and equipment downtime. Power brownouts were a 

common occurrence, and complete blackouts occurred twice. 

Fluctuations in power frequency of +0.5 to +1.0 Hz caused 

station clocks to run fast a1l year, and caused some equipment 

failures and decreased performance. Installation of new power 

plant facilities are tentatively scheduled for 1990-91. 

Satellite data transmissions did not always go smoothly. 

Because of the severely limited ATS-3 satellite window 

available at the South Pole and because of the many projects 

that require satellite data transmissions, competition for satellite 

time is quite keen. Only 2 years ago there was more than 

enough satellite time to satisfy the needs of all the research 

projects there, but because of the South Pole's rapidly growing 

popularity as a desirable location for atmospheric and astronomic research, the satellite time available has quickly become 

insufficient. Also contributing to the difficulty of data 

transmission are the problems of static noise from dry air. 

blowing snow. and daily aurora activity. all of which interfere 

with the transmission antennas. GMCC began compressing data 

files and sending raw binary data as a more economical data 

format. A new LES-9 satellite data link. scheduled to begin 

operation in 1989. should immensely improve this situation. 

The CAMS units are still being improved each year, and 

there were very few problems with them this year. The major 

problem, occasional AUTORESTARTing of the system. was 

anything inherent to CAMS itself, but was caused by periodic 

static discharge in the dry air during periods of high winds. 

2.4.2. PROGRAMS 

Table 2.5 summarizes the programs at SMO. Further 

discussion of some of the programs follows: 

Carbon Dioxide 

Data acquisition with the continuous analyzer was interrupted 

several times by equipmcnt failures. The most common failures 

were of the rubber diaphragms in the sampling pumps. The old 

pumps were replaced with new Air-Cadet pumps after airdrop; 

they proved much less prone to failure. only failing once in 4 

months. The rubber diaphragms of all sampling pumps have 

shortened life spans at the South Pole because of the severely 

dry air. Anothcr kind of failure was of the heating/cooling units 

inside the ana1yzer case. These older units were a1so replaced 

with newer versions after airdrop. 
TABLE 2.5. Summary of Sampling Programs at spa in 1988 

Program 

Gases 

CO, 

COZ,CH4 

Surface 0) 

TOiaIO) 

OzoneprofLIe 

NzO. CFC-12. ere-II, CI 13CO). eel, 

CFC·12, CFC.ll , ",O 

Aerosols 

Condensation nuclei 

Optical propcnics 

Carbon aerosols 

Solar and Terrestrial Radiation 

Global irradiance 

Direct irradiance 

Turbidity 

Albedo 

Terrestrial (lR) radiat ion 

Meteorology 

Air temperature 

Snow temperalUrc 

Pressu re 

Wind (speed and direction) 

Frost-point temperature 

Cooperative Programs 

COz' l3C, NzO (SIO) 

Total surface particulates 

(DOE) 

Aerosol phy sical properites 

(SUNYA) 

Various trace gases (OGC) 

I3C{''C, Cll, (USGS) 

"c (KOAA/ARL) 

Snow acidity (NOAA/ARL) 

Interhemispheric DC/!AC 

(CSlRO) 

1\Oz, 0) (l'\ZARP) 

Cll" CO" CO (NCAR) 

Ul traviolet radiation (!\TSF) 

1\Oz and 0 3 (Vniv. of Rome) 

In strument 

URAS-2T IR analyzer 

O.S·L glass flasks, through analyzcr 

O.S-L glass flasks, p3 

Dasibi ozooe meier 

Dobson spectrophotometer no. 82 

BaUoonbomc ECC sonde 

Shimadzu automated mini-2 gas chromatog raphs 

300-mL stainless steel flasks 

300-mL stainless sleel flasks 

Shimadzu manual GC 

Pollak Cf'C 

Four-wavelength nephelometer 

Aethalometer 

Eppley pyranomctcrs with Q and RG8 filters 

Eppley pyrheliometer with Q, OG I, RG2, 

Sunphotometers with 380-, 500-,778-, 

Eppley pyranometers with Q and RG8 

Eppley pyrgeometers, upward - and 

Platinum resistor, 2- and 20-m heights 

Platinum resistor, 0.5 cm 

Capacitance transducer 

Mercurial barometer 

Bendix Aerovane 

Ilygrometer 

S-L evacuated glass flasks 

High-volume sampler 

Pollak Ci\C with diffusion battery 

Nuelepore filters 

Stainless steel fla sks 

to-L stainless sleel cylinder 

3,000 psi spheres 

12S-mL Nalgene flasks 

S-L glass fla sks 

Spectrophotometer, data logger 

2.5-L sleel fla sks 

UV radiometer, data logger 

Oplieallidar 

12 

Sampling Frequency 

Continuous 

1 pair twice mo· 1 

I pair twice mo'! 

Continuous 

3 day'! 

1 wk-I summer, autumn, winter 

I (3 day)-l spring 

1 sample (3 h- j ) 

1 pair wk'l summer 

3 wk l summer 

2 analyses wk-i (discontinued 

February 1988) 

2 day·1 

G.E. C\C Continuous 

Continuous 

Continuous 

Continuous, summer 

Discrete, summer 

and RG8 filters 

Discrete, summer 

and 862-nm narrowband filters 

Continuous, summer 

filters, downward-facing 

Continuous 

downwa rd-facing 

Continuous 

Continuous 

Continuous 

21jmes wk· t 

Continuous 

Continuous 

2 mo· t (3 flasks sample-I) 

Continuous 

(4 filte rs moo!) 

Discrete 

Contin uous 

Twice mo-l (3 flasks SCI-I) 

I moo! (2 cylinders sample'!) 

500 psi day'! 

I (2 wk)-l 

1 or 2 flasks mo'! 

Continuous for 6 wk 

at sunrise and sunset, 

and conlrol periods in summer 

Daily (scasonaUy) 

Discre le 

Twice day·t 
GMCC O.S-L flasks and SIO S-L flasks were filled concurrently 

twice each month outdoors using the p3 apparatus and, on 

a1temate weeks, they were fined using the indoO! analyzer 

plwnbing. 

Surface Ozone 

Dasibi no. 1328 was installed in November 1987 and worked 

continuously throughout 1988 without mishap. An occasional 

problem did occur, however, with the parallel-ta-serial 

convener. The converter box was apparently responsible for 

sporadicly locking up the weekly automated calibration 

program. When the converter box was unplugged then plugged 

back in, the program would conLinue. 

TOlalOzone 

Dobson specLrophotometer no. 82 was used throughout 1988 

with no problems. The battery-operated clock drive was 

replaced with an electric driven clock in JUly. A minor problem 

that arose from the dirty station power wcu; unstable output 

power from the mercury lamp. During monlhly calibrations 

wilh lhe mercury lamp lhe microarruneter would oscillate by 

±O.s ~, thus requiring visual averaging for lhe recorded 

reading. The oscillation could sometimes be cured by plugging 

the lamp power supply into another electrical ouL1et. 

Ozone Profiles 

Fifly.two successful ozonesonde flights were made; most 

were concentrated in September and Octoher. Balloon tracking 

was limited to approximately 10 mb during the second half of 

the year because of a bad connection on the GMD pre·amp unit. 

It was originally thought lhat lhe pre·amp itseIr had malfunc· 

tioncd, but was later detennined lhat the problem was in a 

soldered connection that had vibrated loose. 

Nilrous Oxide and HalocarbollS 

The only change in any of the GMCC projects was the 

implementation of automated gas chromatographs by the NOAH 

group, which replaced the previously manually operated system. 

It was discovered that drastic room temperature variations have 

most likely been responsible for the unacceptable spread in 

analysis results for the halocarbons over the past few years. An 

effort will be made during the 1989 summer season to correct 

the wide swings in room temperature. 

Aerosols 

The aerosol programs were kept online all year. The Pollak: 

CNC was operated twice daily to provide calibration points for 

the automatic CN counter. Daily checks were performed on lhe 

G.E. CNC and calibrations were pcrformed week.Jy. The four· 

wavelenglh nephelometer operated throughout the entire year 

with the time constant set at 7.3 hours. 

13 

Solar Radialion 

The solar radiation measurements continued as usual. but 

experienced some problems from blown pre·amps and broken 

cables. Both problems seem to be common occurrences at the 

Pole, where the pre·amps are affected by the high static 

electricity and the signal cables become very brillie from the 

culd temperarure. In addition this year, the temperature· 

compensated channel on the albedo pyrgeometer maIrllnctioncd, 

requiring replacement of the instrument. 

Meteorology 

This program continued as usual, but it was not possible to 

corrccL1y calibrate the frost.point hygrometer. Brittle, broken 

signal cables were also a problem and resulted in several days of 

tcmperature data loss on at least three different occasions. 

Cooperative Programs 

Two new cooperative programs required access holes to be 

cut into the roof of the CAF. The first was the University of 

Rome optical tidar. Its main purpose is to record i.he presence of 

polar stratospheric clouds during the Antarctic winter and 

spring. The receiving telescope for the Iidar required a l · m2 

hole with a chimney·like hatch above the roof. The lid of the 

haLCh is swung o~n from above when the lidar is in operation. 

The chimney blocks much of the blowing snow from entering 

the hatch, and also provides a slightly warmed airspace that 

slows frost accumulation on the glass pane that separates outside 

air from room air. Il was originally thought that an air·blowing 

system would he required to prevenl frosl buildup on the glass, 

but in practice it was discovered that no blower is needed as 

long as the outside lid is kept closed while the lidar is not in usc. 

The lidar's Nd·YAG laser operates at the 53.2 run 

wavelength. Combined with a 0.5·m·diameter reflecting 

telescope, the lidar produces 30·m resolution at the lower levels 

and 75·m resolution at the upper levels to approximately 20 km 

above sea level. In its first year of operation the instrument 

recorded the presence of polar stratospheric clouds throughout 

most of the austral winter and into the early spring. 

The other new program that required a roof access was the 

NSF.sponsored UV·B monitoring program. The instrument 

detector is housed in a 1.2 m x I.S m x 1.5 m rooftop enclosure 

that provides "crawl spacc" access by station personnel for 

maintenance. The purpose of this project is to monitor the flux 

of UV·B radiation, particularly during the period of ozone 

depletion. 

The other cooperative programs continued as in the past and 

without notable incident (fable 2.5). 

2.5. REFEREKCES 

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

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

Environmental Research Laboratories, Boulder, CO, 1988. 
3. Aerosols and Radiation Monitoring Group 

B.A. BODIIAINE (Edilor),J.J. DELUlSI, E.G. DUTTON, D.U. LO:-;GEXECKER, D.W. NELSON, P. REDDY. A/o.l) R. STONE 

3.1. CONTh'1UTh'G PROGRAMS 

3.1. 1. SURFACEAER050L5 

The aerosol monitoring program at BRW, MLO, SMO, and 

spa continued during 1988 as in previous years. eN concentration was measured continuously with a G.E. eN counter, and 

daily calibntion points were provided by a Pollak eN counter at 

each sialion. Aerosol scattering extinction coefficient (cr~) at 

the 450·, 550-, 700·, and 850-run wavelengths was measured 

continuously at each station with a four-wavelength 

nephelometer. 

Additions to the routine aerosol monitoring program during 

1988 included an aclhalometer for lhe continuous measurement 

of carbon aerosol at BRW. and a new TSI alcohol-based eN 

counter at MLO. An aethalometer has been operating at spa 

since December 1986, and another instrument will be installed 

at MLO in 1989. New alcohol-based CN counters will be 

installed at BRW, SMO, and SPO in 1989. After a I-yr overlap 

of the new CN counter with the G.E. CN counter at each station, 

the G.E. CN counters will be retired. 

Figure 3.1 shows daily geometric means of eN concentration 

(lower portion of each plot), o~ (middle portion of each plot), 

and Angstrom exponent a (upper portion of each plot) at the 

GMCC stations for 1988. Three independent values of 

Angstrom exponent were calculated from the Osp data using the 

relation 0.;; - 6 log 0sp /6 log A.. The interpretation of a in 

terms of aerosol size distribution was discussed by Bodhaine 

and DeLu;s; [1985). Monthly geometric means of the 1988 

aerosol data are listed in Table 3.1. A graphical presentation of 

the monthly geometric means of me entire data record for the 

four stations is shown in Figure 3.2. 

The BRW data in Figure 3.1 show a asp maximum of about 

2 x 10.5 m· 1 at the beginning of April, typical of the well-known 

springtime Arctic haze. However, chronic problems with the 

BRW nephelometer during some of 1988 produced a rather 

sparse data set. The BRW 10ng-tem1 record shown in Figure 3.2 

clearly shows this annual cycle in O"~. The BRW eN record 

shows a more variable semiannual cycle, having a maximum 

that usually coincides with me maximum in O"sp and another 

maximum in about September. 

The MLO O"sp data shown in Figure 3.1 are atypical because 

of me unusually low values in April and the unusually high 

values in fall and winter. A maximum is expected in April, as 

well as in May, that is caused by the long-range transport of 

Asian desert dust in the upper troposphere to the vicinity of 

TABLE 3.1. Monthly Geometric Means of CN Concentration (em') and Osp (m· l) at 450, 550, 700, 

and 850 run, for BRW. MLO, SMO. and SPO During 1988 

Jan . Fob. March April Hay June July AUO · s.pt . Oct. Nov. Dec. 

B"" 

eN lOB 220 3.3 31. 121 3 •• 4.2 5.2 .. 0 132 ,. 13. 

a .. (4S0) 8.07-6 1.29-S 1.81-S 1.81-S S.S4-6 3.47-6 5.70-6 2.61-6 1.60-S 9.2S-6 1.3S-S 

a., (5S0) 7.24-6 1.17-S l.S9-S 1.S4-S 4.S1-6 2.97-6 S.10-6 2.39-6 1.60-S 7.76-6 1.22-S 

a., (700) 4.98-6 8.11-6 1.04-S 9.71-6 2.80-6 1. 99-6 3.74-6 1 . 72-6 1.29-S 4.89-6 8.19-6 

a., (8S0) 3.S8-6 S . 88-6 7.13-6 6.49-6 1.82-6 l.S2-6 2.91-6 1.36-6 1 . 13-S 3.29-6 6.01-6 

MLO 

CN 211 201 221 155 222 , .. 250 254 241 302 , .. ,., a., (4S0) 1.83-6 2.43-6 2.49-6 1. 96-6 3.S6-6 1. 41-6 1.94-6 1.48-6 2.47-6 3 . 04-6 2.80-6 

a., (SSO) 1.37-6 1.8S-6 1.91-6 1.46-6 2.86-6 1.10-6 1.38-6 1.01-6 1.80-6 2.13-6 1.98-6 

"., (700) 9.30-7 1 . 29-6 1 . 38-6 1.01-6 2.18-6 8.20-7 9.18-7 6.SS-7 1.18-6 1.3S-6 1.24-6 

"., (8S0) 8 . 48-7 1 . 11-6 1.26-6 9.21-7 1.98-6 7.SS-7 7.80-7 S.43-7 9.60-7 1.13-6 1 . 04-6 

SMO 

eN 231 33' 305 2.2 255 221 240 23. 2 •• 304 243 292 

a., (4S0) 1.S6-S 1.S4-S 2 . 02-S 1.42-S 1.93-S 1.60-S 2.41-S 2.01-S 2.22-S 1.S4-5 1.14-S 1. 66-S 

a., (5S0) 1.S1-S 1.49-S 1 . 9S-5 1 . 39-S 1.90-S 1.S7-5 2.4S-S 2.03-S 2 . 23-S 1.47-S 1.09-5 1. S9-S 

a., (700) 1.52-S 1.S0-5 1.9S-5 1. 41-S 1.94-5 1.61-S 2.S9-S 2.12-S 2.32-S 1. 46-S 1.07-S 1.57-S 

a., (8S0) 1.60-S 1.S8-5 2.07-5 1. 49-S 2 .04-S 1. 72-S 2.81-S 2.31-S 2.S0-S 1.S3-S 1.12-S 1.6S-S 

SPO 

eN 14. .5 " 31 18 11 11 ,. 3. •• .0 141 

a., (4S0) 2.74-7 3.20-7 2.31-7 2 .63-7 S . 17-7 6.58-7 4.S6-7 4.5S-7 6.00-7 3.47-7 

a., (SSO) 1.46-7 2.04-7 1.4S-7 1.7S-7 3.92-7 S.08-7 3.20-7 2.89-7 3.86-7 2 . 27-7 

a., (700) 7.08-8 1.09-7 7.67-8 9.42-8 2.33-7 3.41-7 2.1S-7 1. 80-7 2.23-7 1.19-7 

a., (850) S.70-8 7.03-8 4.75-8 S.S8-8 1.S7-7 2.S3-7 1.84-7 1.0S-7 1 . 42-7 9.23-8 

A compact e~ponential format is used for (J~ such that 8.07-6 = 8.07 X 10.6. 

14 
AEROSOL DATA FOR BARROW 

JAN FED MAR APR MAY JUN JUL AUG SE:P ocr NOV DOC 1 ;I~I q~ I I I ,: I·HAff ~ ~ ~ A~ "" 

t , ,?'f . • fl , :\1 ; 

1 , -

/J 

u I 

r~ Til -

~JlII!t ~ Ih. if 

" M 

• 1 V V 

JAN fED MAR APR MAY JUN JUL AUG SEP ocr NOV DEC 

1900 

AEROSOL DATA FOR SAMOA 

JAN FEB MAR APR MAY JUN JUL AUG SE:P ocr NOV DEC 

0 

0 

. 

.-o~ 

oS 

0 

~ 

, 

n E 

.;; 

z , u 

.9 

~~,~~~I~,~~~ I ~~~w~ t~jW N ,C •- ~ 

0" 

~ 

kru j:1 ~I'" 1M o~ }1. PM '1'1 ~ ',fIA,J, i.t. !I<.W 

'('I'" i.rv.J, V ;'I~ frill' -II, ~ L "If "" v-.tJ ~ 

JAN FEB MAR APR MAY JUN JUL AUG SEP ocr NOV DEC 

1900 

0 

7 

19 

• 

· .. 0 ~ 

oS 

• 0 

· 

'" , 

n E 

.;; 

z 

u 

.9 

AEROSOL DATA roR MAUNA LOA 

JAN FEO MAR APR MAY JUN JUL AUG SEP . ocr NOV DOC . 

o 

#$ ;&ff4J -ill; $ W :Eft 

1 

· o 

· 

.n 

'cN 

-"-

-<0 

0 

· 0 

7 

g~ 

~ -. ~o 

.s 

~ n 

~-0 EN 

.;; 

z 

u 

~ 

oS 

o 

M ~~ A~ ,# ,X ~ ' -,' . f. ~ 

1B\i1' ~~ ~J\ W -W-, ~J ', It1V1 Pitn '.~ l :. ' . 

\'w 1. JI\ ,,~ lJu, V. ,~ "'I' '\JIY ~-

I 

" JAN H!:O MAR APR MAY JUN JUL AUG SEP ocr NOV DOC 

1988 

AEROSOL DATA F'OIl SOUTH POLE 

I I ~, I fl~kffl§FRIPkI c R 

JAN FED MAl{ APR MA~ JUN JUL Aue SEP ocr NOV DOC 

~- ~ I.m, u- ~1 ~~ \:::; ~ \ 

• ~r~'i , \. 

~r:;., r • 0 0" of 

\i i '1\, ' tl\~ 

dAAJ .:." . ~ 

. r~ , . U,j Il'!..S I ..... "" .1 

JAN FEB MAR APR MAY JUN JUL AUG SEP ocr NOV DEC 

1900 

0 

0 

0 

. 

. - o~ 

. 

o 

o 

oS 

Fig.3.1. Dail y gcomctric means or as and CN data, and Angstrom exponents, at BRW, MLO, SYlO, and SPO, ror 1988. Data ror MLO are included 

only ror 0000-0800 LST. For each s&tion, CN concentration (bottom) is shown as a solid line; a,p data (middle) are shown ror 450 (dotted), 550 

(solid), 700 (dashed), and 850 nm (long-dashed); Angstrom exponents (a lpha, top) were ca1culated rrom 450- and 550·nm (dotted), 550- and 700-nm 

(solid), and 700- and 850-run (dashed) o~ data. The a.

p

. data ror 850 nm and Angstrom exponent data for 700·850 nm are not shown ror MLO. The 

eN data represented by squares ror SPO arc from the Pouak CN counter. 

Hawaii. The alP values have been generally higher since the 

installation of the new nephelometer in 1985, and have not 

reached the low values expected in winter. An experiment is 

being planned in which a high-sensitivity nephelometer will be 

located at MLO during winter months for a comparison with the 

MLO instrument. This should help determine if the new MLO 

instrument is Jess sensitive than the old one or if Osp has 

generally increased at MLO. The MLO CN annual geometric 

mean for the data shown in Figure 3.1 is 216 em-], probably 

representative of the background mid troposphere in that region. 

The SMO Osp and eN data continue as in previous years with 

no significant annual cyc1e or long-term trend. The SMO 1988 

15 

annual mean is about 1.68 x 10-5 m·1 for o.p (550) and about 266 

em'] for CN concentration, representative of the background 

marine boundary layer in that region. A detailed analysis of the 

entire SMO data record was presented by Bodhaine and DeLuisi 

[1985]. 

The spa eN data (Figure 3.1) show a strong annual cycle, 

reaching a maximum of about 200 cm'] in the austra1 summer 

and a minimum of about 10 cm-] in the winter. Because of 

severe instrument problems with the spa G.E. eN counter, the 

missing eN data were filled with daily means from the Pollak 

eN counter. Instrument problems with the spa nephelometer 

caused loss of data for the entire months of January, February, 
AEROSOL DATA FOR BARROW 

M 

#it+Pf1# I I I 14Hiif 

I. l~ , G I~ 11..11 I ~. I~. L", bw. 

'U iq . ) ... , , ,. \... \ " ' '\ . ii,k • I; _.1 ri , , . , ,. 

Fig. 3.2. Monthly geometric means of asp and eN data, and Angslrom exponents. for the entire data record. Details of the trend Lines are given in 

Table 3.2. 

December. However, the a~ cycle, strikingly different from the 

CN cycle. is still evident. The a~ data generally show 

intennediate values in the austral summer, a minimum in May, 

and large events, sometimes exceeding 10.6 mol, in late winter. 

These large aerosol events (such as occurred in early July and 

late August in Figure 3.1) are caused by the transport of sea salt 

in the upper troposphere from stonny regions near the Antarctic 

coast to the interior of the continent. Analyses of the spa data 

were presented by Bodhaine et al. [1986, 1987J. 

The least-squares trend lines shown in Figure 3.2 were 

calculated using the common logarithms of the monthly means 

of the entire data record, and the results are given in Table 3.2. 

Similar trend lines have been calculated and presented in 

previous GMCC SUmnuJry Reporls. The long-tenn trends are 

still not statistically significant compared with the standard error 

about the regression line, suggesting that there is no long-tenn 

trend in the background aerosol measured at these four stations. 

3.1.2. SOLAR At-.ro THERMAL RADIATION 

16 

IIlJroduClion 

Surface radiation budget. atmospheric transmiSSion. and 

aerosol remote sensing measurement projects at the four 

GMCC observatories continued through the year, and only 

minor modifications were made in the measurement systems. 

Table 3.3 shows the current observatory radiation projects. 

Another ongoing project is the surface radiation budget 

measurements made al the top of the 300-m BAO tower near 

Erie, Colorado. Also, a new temporary surface radiation 

measurement project was planned for the island of Kwajalein 

in the Marshall Islands. Processing and analysis of the data 

acquired during Lhe year is well under way. Results of these 

and other ARM radiation projects during past and previous 

years have been used in numerous studies of surface 

radiation budget characteristics, light-sensitive atmospheric 

TABLE 3.2. Least-Squares Trend Analysis of the Common 

Logarithms of the Data Shown in Figure 3.2* 
TABLE 3.2. Lcast.Squares Trend Analysis of the Common 

Logarithms of the Data Shown in Figure 3.2* 

Parameter Slope Intercept S.E. Trend (% yr-t) 

BRW C~ 0.0156 1.01 0.288 3.66 

cr'P 0.00896 -5.98 0.365 2.08 

MLO CN -0.00624 2.93 0.125 -1.43 

cr'P 0.0255 -8.17 0.313 6.5 

SMO CN -0.00964 3.25 0.110 -2.20 

cr'P -0.00554 -4.36 0.118 -1.27 

SPO CN -0.00593 2.14 0.429 -1.36 

cr'P 0.00660 -7.10 0.189 1.53 

·The time axes in Figure 3.2 are in fractional years, with a data point 

centered at the ccntcr of a month; e.g., Jan. 1974 = 74.042; Feb. 1974 = 

74. 125. 

chemical reactions, satellite algorithm vcrification, climatic 

impact of volcanic eruptions, climatic trends and variability, 

crrors in ozone remote sensing, surface optical properties, 

cloud optical properties, radiative transfer calculation 

verification, instrument development and improvement, and 

solar energy assessment and utilization. All acquired data 

from these studies arc available in the form of various 

reports and publications and/or directly from the ARM 

raJiation project leader. 

ObservaJory Activities 

At BRW improvements were made to the forced-air system 

used to prevent ice buildup on the pyranometer domes. The 

print and stripchart quality of the HP backup data system was 

improved by adding a moisture source in the vicinity of the 

printer head, thus making the charLS and daily summary reports 

more reliably legible. The solar instrumenLS were returned to 

Boulder during the sundown months for recalibration and 

inspection. 

The Mill diffuse pyranometer no. 12502 failed in March 

during a lightning stonn and was replaced in April by 

pyranometer no. 11749. The automated solar tracking dome, in 

which continuous rccording sunphotometers arc housed, 

operated precariously during the year with occasional 

unexplained failures, but it still captured aoout 90% of the 

uscful data periods including unattcndcd opcration on the 

wcckcnds. 

SMO continucs to be a scvere testing site for radiation 

instrumentation, where weather-Light instruments absorb 

moisture, spectral filter matcrial provides a culture for various 

fungal and bacterial decay, and calibration constants drift three 

to four times faster than specifications. Nonc!.heless, the 

program is maintained with relatively frequent instrument 

exchanges and calibration corrections. 

At SPO upward.facing pyranometer no. 12271 was replaced 

by no. 12272 in January 1988. Pyranometer no. 12271 had 

demonstrated an extremely steady calibration over the past 

decade, but lhe base plate had become warped, making leveling 

impossible. The downward-facing pyrgeometer no. 23215 was 

17 

TABLE 3.3. Current Radiation Measurcments 

at GMCC Observatories 

SWD swu LWD LWU RG8D DlRQ r-VlXlP SPlrr~1 ~IJSC 

BRW X X X X X X X X 0 

MLO X 0 0 0 X X X X X 

S~10 X 0 0 0 X X X X 0 

SPO X X X X X X X X X 

X, mcasurcments made; 0, measurcmcnts not madc; SWD, shortwavc 

downward solar irradiance; SWU, shortwave upward (rcflcctcd) solar. 

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

(carth emitted); RGSD, downward solar (RGS filter, 0.7 to 3.0 JUll) 

irradiance; DIRQ, direct solar. FWNIP, filler wheel normal incidence 

pyrheliomcter (discrete observations, four sobr oon<!s); SPlIT:-'1, 

muhiwavelength sunphotomctcr; MISC, misceUaneous-MLO: global 

diffuse solar, dO'A'Jlward solar (OGI filter, 0.53 to 3.0 JUll), 2-channcl 

sllnphotometer (watcr vapor), 3-channel sunphotomctcr (calibration 

standard); SPO: RGS albedo, dircct su n (RGS filter). 

replaced by no. 24333 in November 1988, aftcr the batterypowered circuit failed. Because the pyrgeometer provides lhe 

field personnel with "quick look" quality control capability, it 

was replaced even though t11e battery circuit is not used in thc 

final data analysis. The rack on which the downward -facing 

instruments are located, aoout 90 m grid NE of !.he CAF, was 

replaced in December 1988 with a very sturdy, newly designed 

unit. The rack unit should overcome earlier problems due to 

unstable instrument mounting poinLS and great difficulty in 

constantly raising the rack to maintain a constant height above 

the snow surface. The new rack is designed to keep the 

instruments 2-2.5 m above the surfacc. 

Example Results 

For the past 8 years, nominally once a month, a comparison 

has been made between direct solar beam measuremenLS made 

by an ACR and those made by th e on-line continuous tracking 

pyrheliometer (NIP) at MLO. The ratio of NlP/ACR data is 

shown in Figure 3.3. Each point resulLS from the average of 12 

ACR observations made 15 seconds apart and a simultaneous 

3-min average N1P observation. If more than one 3-min 

comparison is made within a mon!.h, all results are averaged to 

obtained the plotted point for the month. The long and short 

dashed lines indicate the mean and ±2 standard deviations of the 

data excluding the Lhrec very low poinLS in 1984-1985. 

Alt110ugh several rather large excursions arc seen in the record, 

the long-term stability of the relative cali.bration of the two 

instruments is indicated to bellcr than ±O. l %. Some of ·the 

largcr excursions in the recoru arc related to electrical 

measurement problems with the ACR. 

The relative transmission of the aunosphere over MLO, 

commonly called "apparent transmission," is monitored using a 

procedure developed by Ellis and Pueschel (1971). The record 

since 1957 has been shown to be very sensitive to small changes 

in the absolute atmospheric transmission and reveals the effects 

of many volcanic eruptions and othcr aerosol events, as 

discussed by Mendonca el al. [1978]. The most recent 

published account of !.he MLO relative transmission record, its 

water vapor sensitivity, and its physical intcrpre[ation was given 
r===7r~=n~=4··~···7···=····=···=··· =··===4:§ 

~; j!C ............... . ", 0 

~ • 

~ CURRENT nlROUCH 3/89 

o ~~ ! 1962 ! 1981 ! 1984 1985 i! 1986 

YEAR 

1987 " .. 

. . 

J; 1989 • 0 

Fig. 3.3. Time series of the ratio between the continuous tracking NIP 

and the ACR detenninations of the direct solar beam at MLO. The 

comparisons were made sporadically; each plotted point represents an 

average for a given month. The mean and 2 standard deviations of all 

the points, excluding the three lowest, are represented by the dashed 

lines. 

by Dutlon el al. (1985]. The complete record through 1988 is 

given in Figure 3.4. The dramatic effect of the 1982 EI Chichbn 

eruption and the long recovery are evident in Figure 3.4. The 

effects of the E1 Chichon aerosol on the different components of 

solar radiation (direct, diffuse, and total) at MLO were given by 

Dul/on and DeLui,i [1987]. 

3.1.3. SOLAR RADIATION FAClLrrY 

Delivery of the fmal complement of new solar trackers for 

the NOAA network was completed during the first quarter. 

Installation of the first tracker was completed during February, 

at Grand Junction, Colorado. The second unit was sent to 

Columbia, Missouri. By the end of the year, approximately 

one· third of the network was equipped with the new units. 

0_86 

.c.U~.c. LOI. CL(AR - SKY SOLAR TRI.NSMJSSJON tJ c.nt.,Jy o>eroges 

- 12 Month runninq rr,eor, 

0-85 58 60 62 64 66 68 70 72 74 76 78 80 82 84 86 ee 90 

YEAR 

Fig. 3.4. Time series of the MLO apparent atmospheric transmission. 

The theoretical limit is detennined from a LOWTRAN modeled case 

with no aerosol and average MLO water vapor and ozone. The 

theoretical limit could be exceeded for a very dry and low aerosol case. 

18 

Initial installation sites were selected on the basis of minimal 

facilities modification requirements, and coordination with 

NWS regional facilities offices delayed installation of 

subsequent units. All new trackers are operated in Boulder prior 

to field site shipment, and records of tracking performance are 

created for each unit's pennanent file. Tracking accuracy of the 

new units has been excellent. 

In addition to the new tracker checkout and installation 

activities, usual SRF support of the NOAA SOLRAD network 

was maintained throughout the year. Replacement sensors were 

provided when required, and support of the older equatorial 

mount trackers was continued. 

The Boulder SOLRAD sensors and data acquisition system 

operated the entire year, as did the sensors and acquisition 

hardware for the entire network. The year 1988 represented the 

first complete year of SOLRAD network data acquisition using 

the new PC·based data acquisition system. Dial.up access to the 

on·line SOLRAD network data residing on the Climate Analysis 

Center computers was established in August 1988, and plouing 

software developed in Boulder allows plotting of daily network 

data for AFOS·equipp!d sites. Non·AFOS sites are collecting 

data for monthly periods on floppy disks. 

Plots of 1988 Boulder SOLRAD global and nonnal incidence 

(direct beam) radiation as daily sums are shown in Figure 3.5. 

A plot of the 1988 daily sums for the diffuse component is also 

shown. 

Standards activity during 1988 involved comparisons of SRF 

ACRs for repeatability of historical ratios, intercomparisons 

with the SERI reference ACRs, and examination of historical 

ratios. No significant drifts were noted. A WMO·sanctioned 

Region IV pyrheliometer comparison is scheduled for April 

1989 in Ensenada, Mexico, and the NOAA reference, TMI no. 

67502 will be taken there for comparison with a reference ACR 

from the world standard group in Davos. Switzerland. 

SRF calibration efforts for pyranometers focused on 

developing data analysis software for more thorough 

examination of sensor characteristics. Complete characteri· 

zation data can be obtained for any sensor for any day, and plots 

can be generated to illustrate any sensor response curve. In 

addition. a complete bcnch·top electronic calibration system was 

acquired for future use as a DC voltage reference standard for 

the facility. 

3.1.4. TURBIDTrY 

The number of monitoring sites in GMCC's United States 

Turbidity Network declined from 17 to 16. (The terms turbidity 

and aerosol optical depth arc used interchangeably in this text, 

and both refer to the base e fonnula for aerosol optical depth.] 

The NWS closed its station at Salem, Illinois, in November. 

Twelve of the remaining 16 stations continued to send data to 

GMCC in Boulder for reduction and processing. 

Sunphotometers at Sterling, Madison, Raleigh, and Lander, 

however, were used primarily for quality control of 

pyrheliometric data. Turbidity measurements also continued at 

the four GMCC baseline stations. In addition, a five·channel 

Mainz II handheld sunphotometer was put into service at Poker 

Flat, Alaska, during March. Poker Flat is the third ADN station 

.. 
Boulder Soi<lr Radiation 

1908 Daily Tolals 

E 

'" ~ 't---------,--r 

• • 

"rn~~----------------------------------------------------------------------------------, 

E 

'" 7 ,t---------------------------------------------------------------------------------------~ 

• • 

., ~cu~WO--------------------c_--._----------------------------------------------------------_. 

, ·1rh.t.HfftMutI: I 

Fig. 3.5. Daily totals for global, diffu se. and direct beam irradiance at SRF in Boulder during 1988. A pyranometer, a continuously shaded 

pyranomeLer, and a pyrhcliomcler wcre used, respectively, to collcctlhc data. 

to be equipped with a sunphotometer. Another Mainz. II 

instrument was shipped to Australia in November for eventual 

install ation at the ADN station at Perth. Table 3.4 lists the 23 

stations and the wavelengths at which turbid ity was measured. 

GMCC also collected turbidity data in conjunction with five 

experiments conducted during 1988. These experiments are 

listed in Table 3.5. Most of the data from these experiments 

have lx!en processed. A plot of aerosol optical depths mcasured 

on thc NOAA/RITS/C02 cruise is presented in Figure 3.6. The 

data show higher Icvcls of turbidi ty in the northern hemisphere 

and very low levels in the intertropical convergence zone and 

the southern hemis phere. Analysis of data from th ese studies 

continues. 

Approximately 184 sunphotometer calibrations were 

comple ted in 1988; 61 were performed in the mountains west of 

Boulder, Colorado, and 123 at MLO. All calibrations were by 

the Langley plot mcthod and were conducted at elevations of 2.8 

and 3.4 km above sea level. Boulder Turbidity Projcct staff 

participatcd in thc MLO calibration ac tivi ties during March and 

19 

April. During this time. it was noted that suophotomctcrs 

frequently experienced a tempera ture increasc of 10° to 25 °C 

during the course of Langley plot observations. Subscquent 

analyses have indicated that this can result in a bias of about -

1 % to - 1.5% for 380-nm calibrations and - 0.5% for calibrations at 500 nm. Efforts to correct past MLO calibrations and 

the data sets based on these continued at the time this report was 

prepared. Instrument temperatures arc now more carefully 

controlled during MLO Langley plot observation sessions. 

Four Mainz II sunphotometers were returned to the plant in 

Germany for warranty repairs and remained there for most of 

the year. Mainz [] problems contribUied to delays in installing 

sunphotometers at the remaining ADN stations. 

GMCC had 65 sunphotometers on hand in 1988. Because of 

the need for improvcd instruments. the aging of I-series 

sunphotometers, and difficulties with 9 Mainz II sunphotometers, work continued 0 0 the design and construction of 10 

K-series sunphotometers. A prototype was built and tested 

during the summer. Most of the design and construction of the 
TABLE 3.4. GMCCTurbidity Monitoring Sites and Filter 

Wavelengths for Sunphotometers Used at Each Site 

Station 

Barrow, AK· 

.\1auna Loa, m·t 

Samoa· 

South Pole· 

Alamosa, CO· 

Atlantic City, NJ 

Boulder, CO 

Bismarck, i\D 

Caribou, ME· 

Ely,NV 

Haute Provence, Francet 

Huron, SD 

Lander, Wyt 

Las Vegas, NY 

Yladison, WIt 

Meridian, YlS· 

Poker Flat, AKt 

Raleigh, I\Ct 

Salem,IL·§ 

Salt Lake City, UT 

Sterling, VAt 

Tallahassee, FL 

Victori a, TX-

• B A P'\10:\' stations. 

tADN stations. 

SunphOlometer Wavelength (nm) 

380,500,778,862 

380,500,778, 862 

380, 500,778, 862 

380,500,778, 862 

380, 500 

380,500 

380, 500,778,862 

380,500 

380,500 

380, 500 

380,412,500,675,862 

380,500 

380,500 

380,500 

380,500 

380,500 

380,412,500,675,862 

380,500 

380,500 

380,500 

380,500 

380,500 

380,500 

;Not yet reporting data as part of the Turbidity Network. 

§Closed in November 1988. 

mechanical parts for 10 K-series instruments had been fmished 

by the end of 1988. A full-scale circuit had been assembled, 

tested, and corrected by the end of the year. Fifty-five EG&G 

detector-filter-amplifier modules to be used in the sunphotometers were returned for warranty repairs in the fall of the year. 

A summary of station data processed to date is given in Figure 

3.7. A major improvement in instrument quality and calibration 

accuracy occurred from 1982 through 1984. Most of the data 

collected prior to 1982 arc of unknown quality, but are expected, 

in many cases, to be of low accuracy. For example, reconstruction and reanalysis of Boulder data for 1978-1980 and MLO data 

for the 1970's indicated it to be of generally poor quality. 

Data for Boulder (see Figure 3.8) and most other continental 

U.S. stations continue to show a clear annual cycle with maxima 

in the spring or summer months and minima during November, 

December, or January. The impact oCthe EI Chichon eruption in 

1982 is evident at many stations. Data for most GMCC stations 

in the northern hemisphere indicate that the El Chichbn stratospheric aerosol cloud had an optical depth of approximately 0.10 

(al 380, 500, 778, and 862 run) during early 1983, The decay of 

the EI Chichon signal appears as a slow downward trend in 

optical depths since the beginning of the record in early 1983, 

and this decay continued in 1988. The elevated optical depths 

associated with smoke from forest fires in Yellowstone and in 

Colorado are evident in the expanded view of Boulder data for 

1988 in Figure 3.9. 

20 

TABLE 3.5. Experiments Incorporaling GMCC 

Sunpholometer Observations 

Experiment 

N"OAAJRITS/C02 Cruise 

Esperanza €hI Mar Hospital 

Ship Spain Cruise 

NOAA MI. Mitchell Global 

Cruise 

Chesapeake Bay Cruise 

Yellowstone Fire Smoke Study 

Dcscriptionffurbidity Project 

Involvement 

North-south cruise from the North 

Pacific to the South Pacific. Turbidity 

measurements were made to 

complement ocean aerosol studies and 

aid in ground-truthing of satellite 

observations of aerosol optical depths. 

Cruise in the area of the Canary Islands off the northwest coast of 

Africa. Turbidity measurements were 

made to aid in ground-truthing of 

satellite observations of acrosol 

optical depths. NOAA/J\f£SDIS staff 

performed measurements. 

Cruise circumnavigating thc North 

Atlantic. Turbidity measurements 

were made to complement ocean 

aerosol studies and aid in groundtruthing of satellite observations of 

aerosol optical depths. 

Brief cruise of the Chesapeake Bay. 

Turbidity mea surements were made to 

aid in ground-truthing of satellite 

observations of aerosol optical depths. 

NOAAt.\ESDlS staff performed 

measurements. 

Extensive sunphotometer observations made in Boulder (and east of 

Boulder) during August and 

September to characterize smoke 

aerosols from foresl fires in Yellowstone National Park and in Boulder 

County. 

BRW data are presented in Figure 3.10. It is believed that 

BRW data have a maximum bias of about 0.01 to 0.015 at 380 

nm because of a temperature-dependent bias in calibrations obtained at MLO. The temperature dependent bias is believed to be 

negligible at 778 nm. Arctic haze events in the spring shift the 

maximum in the annual cycle to early spring. 

As indicated in the 1987 Summary Report (Bodhajne and 

Rosson, 1988], the SPO staff formerly made sunphotometer 

observations through an open window. in the CAF. Cold air 

pouring into the heated room caused density discontinuity waves 

in the air around the window. Sunlight was apparently focused in 

some areas of the wave field, and the peak-hold feature of the 

sunphotometer stored the maximum signal received within the 

measurement period. This resulted in an artificia1ly high reading 

and correspondingly low computed optical depth. This 

phenomenon has been duplicated at Boulder during observations 

made in subfreezing weather near a building air exit vent on the 

roof of lhe ERL building. The 1988-1989 spa crew look one 

observation from outside the open window of the CAF for each 
0.' 

: 0.4 ~ 

~ 380N": w 

Q SOON .. -.......... ~ 0.3 ~ 

~ 

;: 

~ 

0 • ~ 0.' .•. 0 

00 

0 

~ 

w • ~ 0.1 

.. ·-t' .•. 

0 

- 10 -5 0 , 10 15 ZO Z5 

DEGREES LATITUDE 

Fig. 3.6. Aerosol optical depths at 380 run and 500 nm measured on !.he 

l\OAA/RlTS/C02 cruise. 

observation taken from inside the building. Figure 3.11 shows a 

sample of aerosol optical depths computed from these observation pairs. The data appear to confinn the hypolhcsis thaI 

readings from within the CAF are often elevated and yield 

erroneous, lower optical depths. About half of the data obtained 

from wilhin the building compare well with those obtained from 

outside. This distribution of apparently valid and erroneous 

optical depths for measurements made inside suggests a method 

for reconstructing the spa record for years when readings were 

made from within the CAF. 

STATIOII 1l 1] 14 7~ 1~ 11 ,. 19 10 II 12 I l 1 4 IS 16 11 at 

At.O.lIOSA 

AT(AflTIC CITY 

IIISKARCK 

CARI1ICIU 

• IiIIROH 

u.s VeGAS • "ERlDIAH 

SALT I.\.I([ • TALLAH AS SEE 

VICTORIA # {r 4 

6A.RROIl 

J 

S"",OA ------"" p 5 e J 

SOOn! POL£ 

I I(I:Y , _'. eARLY NI."nIORK. V.UQIO\iJI QUALITY. I .UGH QUALITY. 

Fig. 3.7. Status of turbidity data from the U.S. network and GMCC 

baseline station s. 

21 

~ 

~ 

Q 

;;; 

~ 

~ 

~ 

~ 

~ 

Q 

;;; 

~ 

~ 

~ 

0.75 

+ + 

0.' + + 

0.25 

0 

0.75 

0.5 

• 0.25 • 

380 NY 

• 

.. 

• + + 

+ • 

YEAR 

778 NY 

• 

+ 

+ 

+ 

1982 1963 1984 1985 1988 198? 1988 1969 

YEAR 

Fig. 3.8. Daily average aerosol optical depths at 380 nm (upper) and 778 

nm (lower) for Boulder during 1988. 

380 Ii'" 

YEAR 

• 

• 

1969 

Fig. 3.9. Daily average aerosol optical depths at 380 nm for Boulder 

during 1988, showing forest fire smoke events in August and September. 
3BO HW 17B HW 

0.75 0 .75 

~ , , ~ ~ • ~ 

Q , "- Q .. 0.5 , .. 0.5 ~ , ~ 

~ 

~ t , ~ ~ / t ~ 

, .. , 0 .25 t ~4 .~ i' " 0.25 \, t;' 'i .. , , t'~ , ff, U , , • " • "r " '\-!t-~ • t .. ~ t4 , 0 , 1982 1983 1984 1985 1966 1967 1968 1989 1982 1983 1964 1985 1966 1987 1966 1969 

Y£AR YEAR 

Fig. 3.10. DaiJy average aerosol optical depths at Barrow for 380 nm (left) and 778 nm (ri ght). 

SPO 380 NI.I AEROSOL OPTICAL DEPTH - W(ASUR(D INSIDE SPO 380 NW AEROSOL OPflCAL DEPtH w[ASUR[O OUTSID( 

0.05 +~_.L~_.L~_.J....~_-'-~--'-'~-i 0.05 +_~--'-_~-'_~_L~_L~_..L _~-1 

O.Ol!! 

, 

~ ~ + + + . -- -----. _. _. ----. --- --.+ ... -+' .. .. .... . . . --"';' _ .. - - - -- 0.025 • __ •• __ ••• _____ • _______ +_. *+ _ .... ______ "* ..... .. ___ + + t ____ . __ .. .. 

, 

o --. ----_ .-.... -- ......... -- -. -- -. --.'. --. ---- ------- o ---" --.... -- --- --. -------. _ ... . --. --. -- ... -- --- -----

- 0.02!! --. - . • -... --- -.---- -.--.- ----.-- -- --- ----. -- ---..... . -O.02!! --- - - ---.. - -••. • . -- .••• -- .• --. ------••.. -----.. --. ---

o , 10 " 20 25 30 o , 10 " 20 25 30 

DAY' OF MONTH - NOVEMBER 88 OAY OF WONTH - NOVEMBER 88 

Fig. 3.11. SPO 380·nm aerosol optical depths measured from within the CAF through an open window and from outside the. CAF. 

3.2 . SPECIAL i'ROIECfS 

3.2. 1. SPO AEROSOLMEASURE'IE~'fS DURIKG 1987 

Introduction 

The flrst year of a"p data from SPO, presented by Bodhaille 

and Bortlliak [1981], sho d an annual cycle strikingly 

different from the CN record, being dominated by sea sal t 

events in the austral winter. An aerosol chemistry experiment 

was conducted during 1982, and the results were presented by 

Bodhaine el al. [1986, 1987J. 

In 1987 a more extensive aerosol experiment was conducted 

thai included aerosol filter samples for PIXE analysis. aerosol 

size distribution measurements in the Aitken size range, and 

aerosol black carbon measurements. Results of the 1987 

experiment are presented here. 

IlISlrumenJalion 

CN concentration is measured continuously with a G.E. 

automatic CN counter [Skala, 1963]. Calibration points for the 

automatic CN counter arc obtained Iwice daily with a Pollak CN 

22 

counter [Metllieks and Pollak, 1959J. The operation and 

calibration of the automalic instrument at the South Pole were 

discussed by Bodhaine and Murphy {1980}. 

A four.wavelength nephelometer similar in design to thal of 

Ahlquist and Charlsoll [1969J measures alP continuously with 

approximalely 4·h time resolulion at the wavelengths 450, 550, 

700, and 850 run. The asp measurements arc most sensitive to 

particles having diamelers in the 0.1- to 1.0')lITI diameler range 

(the accumulation mode) whereas CN concentrations tend 10 be 

dominated by particles smaller than 0.1-~ diameter (the Aitken 

mode). Since particles in the 0.1 - to l.O-J..Im range tend to 

dominate the total background atmospheric aerosol mass, O'IP is 

often representative of aerosol mass. The CN measurements 

provide a good indication of any local pollution events that 

could interfere with the routine monitoring program. 

Aerosol size distribution in the Aitken size range was 

measured using a Nuclepore.filter diffusion battery instrument 

construCled at GMCC. Six airOow paths consisting of four 

paths through 8-, 5·, 2-, and 1.).UTI-pore-diameter Nuclepore 

filters, one path through an absolute filter, and one straightthrough path. were activated sequentially by motor-driven ball 
measurements and the inversion method to recover the size 

distributions were described by Twomey [1 9751 and reviewed by 

Heidam [1981]. 

The black-carbon component of the aerosol was measured 

with an aethalometer constructed at Lawrence Berkeley 

Laboratory [/-/ ansen et af., 1982]. This instrument was 

described in detail by Bodhaine el al. [1989]. Since carbon is 

by far the dominant absorber in the atmospheric aerosol. the 

measurement of light absorption using this instrument is 

essentially a carbon measurement [Rosen el al .• 1978]. 

An HP-71 computer and HP-3421 data acquisition and 

control unit were used to control the diffusion battery and 

acquire all data from the instruments. Data were stored on 

cassette tapes with a time resolution of 1 hour. 

Results 

Daily geometric means of eN concentration and o~ for 1987 

were presented by Bodhaine arul Rosson [1988]. The month of 

July was chosen to examine relationships among the various 

measured variables because the first half of the month appears to 

be representative of background conditions and the second half 

is dominated by large events that may contain sea salt. Figure 

3.12 shows <l"P' eN concentration. black carbon concentration, 

and fraction of eN penetrating a NucleJXlre filter for July 1987. 

The general level of <l~ during the last half of the month is 

nearly a factor of 10 higher than during the first half of the 

month, and seems to be dominated by individual events. The 

major peaks in eN coincide with the peaks in <lsp: however. the 

overall level for eN is relatively not as high as for cr~, suggesting an influx of larger particles during the last half of the month. 

The major peaks in aerosol carbon generally coincide with 

those in <lsp and eN, and occasionally exceed 1 ng m-3. The two 

carbon peaks on July 28 probably were caused by local 

pollution; the cause of the large carbon peak on July 30 is 

unknown. 

The fraction of eN penetrating a Nuc1epore filter with 

2-llJ11-diameter pores (Figure 3.12. bottom) suggests a shift 

in size distribution toward larger sizes during the last half of 

July. Although the eN-fraction data are somewhat noisy. it is 

apparent that the major eN-fraction peaks tend to coincide with 

the major cr~ peaks. Again, this suggests that an additional shift 

toward larger sizes occurs during large cr~ events. 

Figure 3.13 shows a time-height cross section of temperature 

for July calculated from South Pole rawinsonde data. The 

strong, shallow surface temperature inversion is persistent 

during the entire month. However. on July 17. the time of the 

transition in aerosol data, the strength of the inversion decreased 

dramatically and a wann air mass moved in at about the 600-mb 

level. Trajectories typical of the first and last halves of July are 

shown in Figure 3. 14. The direct, rapid transport, evident on 

July 23 near the maximum of the warm event, arrived from the 

Weddell sea in less than 2 days. The July 12 trajectories were 

slow moving and remained over the continent for up to 7 or 8 

days back. 

23 

'" , 

E 

g 

z 

" 

~ 

"" , 

E 

c 

.2 

1l 

~ • 

z 

" 

2 

, , 

Q2, 3 5 7 9 11 13 15 17 19 21 23 ~ 27 ~ 31 

July 1987 

Fig. 3.12. spa aerosol data for July 1987: 0" for 450 (dOlled), 

550 (solid), 700 (das hed), and 850 nm (long-dash~d); CN concen tration; black-carbon concen tration; and fraction of CN penetrati ng a 

2-J.Lm-pore-diameter Nuclepore filter. 

:c 

.s 

[1! 

" "' "' [1! 

CL 

400 

500 

-70 -70 

3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 

July 1987 

Fig. 3.13. Time-heigh t cross section of temperature rC) for July 1987 

at SPO. 
60' ., 

80' ., 

100' W 

60' S -

1110' ... 

1'0' ... 

" . 

60' S ~ 

180' ., I~'[ 

... Go' E 

,;m' [ 

Fig. 3.14. Isobaric trajcctorics calruiatcd backward from thc South Pole at 0000 UTe (A) and 1200 UTe (B) on July 12 (left) and July 23 (right), 

1987, at thc 500-mb lcvel. llte numbers on thc trajectories indicate the number or days back. 

The black carbon data for the entire experiment are shown in 

Figure 3.15. Maximum values of about 2-3 ng m-) occurred 

during the austral summer and minimum values less than 0.1 ng 

m·3 occurred in aJx,ut April-May. TIus annual cycle resembles 

the annual cycle in asp data, suggesting that the aerosol carbon 

may be related to long-range transport from oceanic regions or 

[rom lower latitudes in general. 

Conclluions 

Surface-based aerosol measurements at the South Pole 

clearly show annual cycles in CN concentration, a~, and black 

carbon concentration. Large-scale back trajectories show that 

rapid transport paths can exist from the coast of Antarctica to 

the interior, during which large events occur in the aerosol data. 

Large-scale transport in the troposphere and mixing to the 

surface during periods of weakened surface tcmperature 

inversion arc responsiblc for evcnts in the surface aerosol data. 

10 .-------- -----

01 

001 DEC 1 JAN rm~;; r;;;; , MAY 1 JUN 1 JUl 'AUG I SEP 10CT I NOV 

1986 1987 

Fig. 3. 15. Black carbon concentration (ng m·3) at SPO during 1987. 

llte solid circles represent data calculated from hou rly data; the open 

circles are data from the operator's daily checks. 

24 

3.2.2. SliRFACE RADIATION A?\'D TEMPERAl1JRE VARlAllONS 

ASSOCIATED Wml CLOUDL .... 'ESS ATTIIE SOlJIl-l POLE 

Introduction 

Results from ERBE indicate that although clouds have a net 

cooling effect on the surface of the earth on a global scale, !.hey 

may contribute to anomalous surface heating in high-latitude 

snow-covered regions {Ramanathan et al., 1989]. Past 

trajectory analyses show that upper-level intrusions of warm, 

moist air and cloud condensation nuclei frequently reach the 

South Pole from the Weddell Sea, producing a variety of cloud 

types [Ohlake, 19781_ Preliminary analysis of the 1986-1987 

spa data presented here relates surface warming to enhancements of longwave downward radiation associated with such 

transitory cloud systems. 

Data 

Daily mean values of "surface" temperature measured at 2 m 

fT,), longwave downward radiation (L WO), and the direct-beam 

irradiance (DB) from Dutton et al. (1 989] are analyzed. These 

quantities are correlated with daily mean total sky cover (SC) 

estimates. Figure 3.16 is a time series for 1 year, beginning 

September 1986, of TI , L\VD with SC, and DB, respectively. 

The smooth curves represent empirically detennincd clear-sky 

conditions for the peak sunlit months, November-January (NOJ, 

dashed), and the dark winter months, April-August (AJvtJJA, 

dotted). Refer to Stone et al. (19891 for a detailed description of 

how these curves were fitted. 

Clear-sky conditions are typically characterized by a weak:, 

steady flow of cold air from higher terrain and a slrong, 

persistent temperature inversion in the lower lroposphcre. 

Transitory disturbances are characterized by cloudy skies, a 

dramatic decrease in DB, an increase in T,. and a weakening of 

the inversion and an enhanced L WO signal as is evident by 

departures from the smoothed clear-sky curves in Figure 3.16. 

Analysis 

Scatter plots ofT, versus LWD for months NDJ and AMJJA 

are shown in Figure 3.17. Each plot is fitted with a quadratic 
Fig. 3.16. Time series of (a) surface temperature, (b) longwave 

downward irradiance Oine referenced to left scale) and sky cover (bars, 

right scale), and (e) direct-beam irradiance, at SPO for I year beginning 

September 1986. The smooth curves represent clear-sky conditions 

described in the text. The inverted arrow in b indicates missing sky 

cover data. 

-'·'-~(b-)-.~-r~~-r~~-r~I-r~·r-·-r--. 

RSO = .3 . 47 ..... / 

-.. ~ 

U 

o 

-..- -60 

COR = 0.91 ... 

I I I 

10 100 110 

• • 

• 

• 

LWD (W/m') 

• • 

I 

11. 

Fig. 3. 17. Scatter plots of SPO surface temperature vs. long wave 

downward irradiance for (a) November-January 1986-87 and (b) 

April-August 1987, fitted with quadratic functions. RSD is the residual 

standard deviation of fit, and COR is the correlati on coefficient. 

25 

function. The residual standard deviation (RSD) of fit and 

correlation coefficient (COR) arc given in each figure. Note (in 

Figure 3.16) that the range of clear-sky temperatures during 

AMJJA is only about 1O"C, whereas the total observed range is 

close to 40·C; the wannest temperatures correlate with enhanced 

values of LWD. Because clouds over the pole tend to form in 

the wannest layers near the top of the inversion and 8.!"" more 

emissive than clear air, thermal emissions from clouds are 

normally greater than thennal emissions from the relatively 

cool, dry subcloud layers. Thus, observed enhancements of 

LWD are mostly attributed to cloud "greenhouse" effects. 

To quantify the relationship between departures of temperature from clear-sky conditions and the observed LWD enhancements, ratios of observed L WD values to corresponding 

predicted dear-sky values were computed to estimate the 

fractional LW-radiative forcing (LWRF) associated with clouds. 

The largest values of LWRF correspond to optically thick 

clouds. It is hypothesized that during the initial stages of a 

warming event, when clouds arc decoupled from the surface by 

a strong intervening inversion layer, L WRF is dominated by 

wann cloud emissions. As radiative exchanges between the 

cloud base and the surface occur, and turbulent and advcctive 

processes progress, dynamic forces arc increasingly important in 

controlling the surface temperature field. On the basis of the 

available data, only the relationship between L\VRF and the 

observed temperature perturbations, expressed in tenns of 

temperature differences, .6T = T. (measured) - T. (clear), is 

presented here. This relationship is shown for the months ND] 

and AMJJA in Figures 3.18a and b, respectively. 

During the winter months, positive temperature differences 

are highly correlated with LWRF, but during NO] there is 

virtually zero correlation for small LWRF and increasingly 

positive correlation as LWRF increases (i.e .. for optically 

thicker douds). It is likely that shortwave albedo effects 

involving multiple reflections (not yet accounted for in our 

analysis) may compete with, or add to, the LW (thennal) effects, 

thus greatly complicating the determination of the net radiative 

forcing caused by thin. broken or scattered clouds during the 

summer months. 

Conclusions 

Preliminary analyses of the 1986-1987 spa data indicate that 

positive L W radiative forcing may occur whenever clouds of 

sufficient optical depth and sky cover are present. Under such 

conditions the surface actua1Jy tends to warm, supporting the 

preliminary analysis of the ERBE data. These results suggest 

that transitory clouds may have a potentially important role as a 

source of heat for the Antarctic Pl ateau and, as such, must be 

accounted for to improve model simula tions of the total surface 

energy budget for that region. Detailed case studies involving 

analyses of the physical and optical properties of clouds and the 

components of the surface energy budget in conjunction with 

studies of synoptic and local dynamical mechanisms arc 

necessary to understand further the effects clouds have on the 

temperature field at Lhe South Pole_ 
" (b) • 

" 

,. 

RSO ; J.86 • • • COR ; 0.85 •• • • • ~ ~ " • • 

,. • 

>- I 

<l 

, • • 

• 

-, 

0.' 1.1 1.2 I.J I." 1.' l.iS 1.7 1.8 1.9 

LWRF 

Fig. 3.18. Scaucr plots with quadratic fits of observed temperature 

differences versus longwave radiative forcing for (a) November 

t986-January 1987 and (b) April-August 1987, at SPO. RSD and COR 

values are as noted. 

3.2.3. CAUBRATIO>l OF TIlE SBUV USING UMKEHR 

MEASUREME!\iS 

introductjon 

Experience has shown that the diffuser plate calibration of 

the SBUV satellite does not remain stable with time and that the 

total ozonc and ozone profile data deduced from the SBUY 

albedo measurements have displayed significant drifts with time 

when compared with ground-based observations [Fleig et al., 

1981; Cebula et 01., 1988]. Attempts to correct the SBUV 

calibration drift independently of any external reference have 

not been satisfactory. Fleig et al. [1988] showed that a drift in 

total ozone and profile ozone still existed after a first-order 

diffuser plate correction had been applied. 

Results are described here of an investigation that directJy 

relates a ground-based UV measurement to backscattered 

intensities, which can be used to monitor the calibration of the 

SBUV. For UY measurements the Umkehr method was used 

because of the abundant data that are available for the time that 

the SBUV was in operation. The method developed eliminates 

the need to estimate ozone profiles and instead directly relates 

the Umkehr measurement to the albedo measurement from the 

satellite-borne SBUV. The SBUY and Umkehr wavelengths are 

shown in Table 3.6. 

26 

TABLE 3.6. SBUY Satellite Instrument and Umkehr 

Wavelengths 

SateUite (nm) UmkellT (nm) 

273.S 30S.5 

283.0 311.4 

287.6 317.6 

292.2 32S.4 

297.S 332.4 

301.9 

30S.8 

312.S 

317.S 

331.2 

Relating the Umkehr to the SBUV 

The C wavelength pair was used as the Umkehr vector, and a 

linear regression T matrix was constructed from 62 samples . 

The least-squares solution is given by 

where 8M is the Umkehr vector, 84 is the predicted SBUV 

albedo expressed as departures from the mean, and 1\ denotes 

predicted values. The mathematical forms of the M and Q 

vectors are 

1< ; 100 loglO[I(332.4)1I(311.4)] 

- 100 log,olFo(332.4)IFo(311.4)] 

g ~ \og,o[l,(l.)IFo(l.)] 

where I is zenith sky intensity, Fo is extraterrestrial solar nux, 

IsCA.) is intensity going back to space seen by the satellite, and A 

is wavelength in nm. Ozone profiles used to calculate M and g 

were obtained from SAGE]] data for 1985 and 1986 aI 40'N 

latitude. The elements of the M and 4 vectors are N-values. 

Randomly distributed errors for the Umkehr (£11 = ±O.5, ±l.O, 

and ±3.0 N-units) and for the SBUV (Eo ~ ±O.7%) were applied 

to simulate measurement unCCTtainty under idealized clear 

aunospheric conditions. 

Results 

Figure 3.19 shows the root-mean-square errors (aa) obtained 

by comparing the predicted.4 with "truth" g for the Dobson C 

wavelength pair for an SBUY solar zenith angle of 30·; random 

errors (constant over the interval) of ±O.5, ±1.0, and B.O N-units 

for the Umkehr data; and random error of ±0.7% for the SBUV 

measurements. In this figure, the plot on the right is the error 

for all SBUV albedo data. This plot represents the first-guess 

statistics. The other plots represent the improvement (in terms 

of error reduction) provided by the infonnation contained in the 

Umkehr measurements. The plot in which £11 = 3.0 represents a 
M 

m 0.5 1.0 3.0 

! ~ 

'" ... m 

to 

Z 

"' ~ .., 

~ ,,, 

'" 

" 

,» 

, .. • " " " " " " " 

% ERROR 

Fig. 3. 19. Estimated SBVV albedo errors (+; O'a_a in the text), shown 

as wavelength versus percent root-mean-square error of estimation. The 

conventional Umkehr C pair was used for the estimation. The three 

plots on the left arc the Umkchr errors in terms of N-values. 0.5, 1.0, 

and 3.0. The plOl on the right is the standard deviation for all SBUY 

data. The SBUV solar zenith angle was 30', 

severe-error case. An error of 1 N-unit is more likely to be 

encountered with the Umkehr measurement. Re-examination of 

the figures shows that the C pair provides reasonably good error 

reduction ati-.!! in the estimation of the albedos. Even in the 

crg_Q severe case, there is reasonably useful error reduction. 

The values seen in the two longest wavelengths (for total 

ozone) are small because ozone absorbs weakly at these 

wavelengths, and there is virtually no ozone profile information. 

SBUV total ozone is detennined from these wavelengths, but 

normalization of the Umkehr at a solar zenith angle of 60 G 

essentially removed most of its total ozone information. The 

SBUV 30S.8-nm wavelength shows the largest variation 

because it optimally senses ozone profile information in the 

region of the ozone maximum, where the absolute total ozone 

changes are also a maximum. 

Plots are shown of simulated SBUV albedos and Umkehrestimated SBUV albedos in Figure 3.20 to illustrate the 

capability of our method for sensing the annual variation of 

SB UV albedos. The ordinate is in terms of .4 , the frac tional 

departure from the mean go. The dashed line connecting points 

gives the Urnkehr-estimated SBUV albedos at 283 .0 run using 

lhe A-C-D pairs. The abscissa is the year and fraction of that 

year. The solid line connecting the points gives the simulated 

SBUV albedos. The Umkehr error was set at ±1.0 N-value. 

This figure reveals an expected annual variation, in accordance 

with the SAGE II observations, which formed the basis of the a 

priori ozone profile information used in the retrieval algorithm. 

Conclusion 

The preliminary results of the present investigation suggest a 

potentially advantageous retrieval method of using groundbased UV measurements to track the calibration drift of an 

SBUV satellite. Dobson standard or short Umkehr measurements with verifiable calibrations can be used as the ground-

.~ 

." 

... 

." 0 

Q ." 

"' OJ .., 

'" -.<11 

-.Ol 

-.0) 

--" 

-.~ 

, 

, ' 

, 

"., 

" , , , 

" 

, 

" 

, 

"., "_. "_. 

YEAR 

" , 

, , 

,- , 

, , 

, 

, 

" , 

"_. n .' n .• n_. ~-. ~~ 

Fig. 3.20. Estimated SBUV albedos using Umkehr A-C-D pair data 

(dashed lines) and simulated "truth" SBUV albedos (solid lines) for a 

period of 1 year. The simulated Umker Q. A-C-D pa ir error is ±1.0 

N-un it. Ordinate values are in tenns of the fractional depa rture from the 

algorithm mean value Go (see text). The abscissa is year and frac tion of 

that year. SBUV wavelength is 283.0 nm. 

27 

based measurements for the present investigation because of 

their availability and potential stability. The GMCC Automated 

Dobson network will provide ample Umkehr data for 

comparisons. 

The satellite SBUV albedo-estimation procedure indicates 

that the retrieval random errors are about ±S% or less for an 

Umkehr error of ±l.O N-unil. These errors are believed to be 

close to the tolerances required for the validation of mathematical methods devised to correct the calibration drift of the SB UV. 

An error analysis that includes instrument errors, biases, and 

stratospheric aerosol interference errors was not done in the 

present investigation but is suggested as a future research topic. 

More work is required to develop a general algoritlun to account 

for more SBUV solar zenith angles and latitudes. 

3.3. REFERENCES 

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dependence of almospheric eJ{linction due to scalier, A/mos. 

Environ., 3, 55 1-564,1969. 

Bodhaine, B.A., and J.c. Bortniak, Four wavelength nephelometer 

measurements at South Pole, Geophys. Res. Letl .• 8, 539-542, 1981. 

Bodhaine, B.A., and 1.1. DeLuisi, An aerosol climatology of Samoa, 1. 

A/mos. Chem., 3,107-122,1985. 

Bodhaine, B.A., and M.E. Murphy, Calibration of an automatic 

condensation nuclei counter at the South Pole, J. Aerosol Sci., 11, 

305-312, 1980. 

Bodhaine, B.A., and R.M. Rosson, Geophysical Moni/oring for ClinuJ/ic 

Change, No. 16: Summary Report 1987, pp. 16· 19, NOAA Ai.r 

Resources Laboratory, Boulder, CO, 1988. 

Bodhaine, B.A., 1.1. DeLuisi, J.M. Harris, P. Houmere, and S. Bauman, 

Aerosol measurements at the South Pole, Tel/us, 38B, 223-235, 

1986. 

Bodhaine, B.A., 1.I. DeLuisi, I.M. Harris, P. Houmere. and S. Bauman, 

PIXE analysis of South Pole aerosol, Nucl. Ins/r. Meth., 822, 

241-247, 1987. 
Bodhaine, B.A., E.G. Dutton, J.1. DeLuisi, G.A. Herbert, G.E. Shaw, 

and A.D.A. Hansen, Surface aerosol measurements at Barrow during 

AGASP-ll, J. Almas. Chem., 9, 213-224, 1989. 

Cebula, R. P., H. Park, and D. F. Heath, Characterization of the 

Nimbus-7 SBUV radiometer for the long-tenn monitoring of the 

stratospheric ozone, J. Almos. Oceanic Technol., 5, 215-227, 1988. 

Dutton, E.G., and 1.1. DeLuisi, Measurements of solar radiation at 

.\1auna Loa observatory, 1978-1985, with emphasis on the effects of 

the eruption of El Chichon, NOAA Dala Rep. ERL ARL-J3, 35 pp., 

NOAA Air Resources Laboratory, Boulder, CO, 1987. 

Dutton, E.G., J.1. DeLuisi, and A.P. Austring, Interpre13tion of .\1auna 

Loa atmospheric transmission relative to aerosols, using phQ(ometri c 

precipi13ble water amounts, J. Almas. Chem.,], 53-68, 1985. 

Dutton, E.G., R.S. Stone, and 1.1 DcLuisi, South Pole surface radiation 

measurements, April 1986 to February 1988, NOAA Dalo Rep. ERL 

ARL.J7, 49 pp., NOAA Air Resources Laboratory, Boulder, CO, 

1989. 

Ellis, l-I.T., and RF. Pueschel, Solar radiation: Absence of air pollution 

trends at Mauna Loa, Science, 172, 845-846, 197 1. 

Fleig, A.1., K.F. Klenk, P.K. Bhartia, K.D. Lee, e.G. Wellcmeyer, and 

V.G. Kaveeshwar, Vertical ozone profLle results from Nimbus-4 

B UV data, Proc. Founh ConL on Aunosphcric Radiation, Toronto, 

Ontario, June 16-18, 1981, pp. 20-26, American .\1cteorology 

Society. Boston, 1981. 

Fleig, A.1., D.S. Silberstcin, e.G. Wellemeycr, P.K. Bhartia, and U. 

DeLuisi, An assessment of the SBUVrrOMS ozone da13 quality, 

based on comparison with external data, Atmospheric Ozone, 

International Ozone Commission, in press. 1989. 

lIansen, A.D.A., H. Rosen, and T. Novakov. Real-time mcasurement of 

the absorption coefficient of aerosol particles, Appl. Opl., 21, 

3060-3062, 1982. 

Heidam, N.Z., Review: Aerosol fractionation by sequential filtration 

with Nuclepore filters. Almas. Environ., 15, 891-904, 1981. 

Mendonca, B.G., KJ. l'lanson, and U. DeLuisi, Volcanically related 

secular trends in atmospheric transmission at Mauna Loa, Hawaii • 

Science, 202.513-515. 1978. 

Metnicks, A.L, and L W. PoUak, Instruction for use of phOlo·electric 

condensalion nucleus counters, Ceophys. Bull. No. 16, School of 

Cosmic Physics, Dublin Institute for Advanced Study, Dublin, 

Ireland, 1959. 

Ohtake, T., Atmospheric ice crystals at the South Pole in summer, Ani. 

J. U. S" 13,1 74-175,1978. 

Ramanathan, V., R.D. Cess, E.r. Hamson, P. Minnis, B.R. Bariwrom, 

E. Ahmad, and D. Hartmann, Cloud-radiative forcing and climate: 

Results from the Earth Rad iation Budget Experimen t. Science, 243. 

57-63, 1989. 

Rosen, H., A.D.A. Hansen, L Gundel, and T. Novakov. Idenlificalion of 

the opticaUy absorbing component in urban aerosols, Appl. 01'1., 17, 

3859-386 1,1978. 

Skala, G.F., A new instrument for the continuous measurement of 

condensation nuclei, Anal. Chern .• 35, 7fJ2-706, 1963. 

Stone, R.S., E.G. Dulton, and U. DcLuisi, Surface radiation and 

temperatu re variations associated with cloudiness at the SOlllh Pole, 

Ant.J. U. S., in press, 1989. 

Twomey, S., Comparison of constrained linear inversion and an iterative 

nonlinear algorilhm applied to the indirect estimation of particle size 

distributions,J. Compo Phys., 18, 188-200, 1975. 

28 
4. Carbon Cycle Group 

TJ. CONWAY (Ed;tot). K.W. THONING, L.P. STEELE, P.c. NOVELU, L.S. WATERMAN', 

P.P. TANS, D.G, KITzIS, P.M. L ANG, R.C. MARTIN, AND K.A. MASARlE 

4.1. CONTINUING PROGRAMS 

4.1. 1. COl\~rNUOUs IN-SITU Al\1) FLASK SA~tpLE 

CARDON DIOXIDE MEASUREMEl\'TS 

The in-situ NDIR continuous measurements of CO2 at the 

four GMCC observatories were made in 1988 as in previous 

years. Preliminary monthly and annual mean CO2 values are 

shown in Table 4.1, expressed in the WMO 1985 mole fraction 

scale (X85). Calibration procedures for CO2·in-air reference 

gas tanks remained the same as in previous years. Only minor 

modifications in sampling methodology occurred in 1988. 

Second parallel sampling lines were installed at SMO and MLO 

in March and April, respectively. Air is sampled for 25 minutes 

of each hour from each of the two lines. The remaining 10 

minutes of the hour are used for measurement of calibration 

gases. The dual sampling lines will allow better quality control 

of the CO2 measurements. Comparison of the results from one 

line to the other will make it possible to spot problems in a line 

or pump and to have a backup in case one sampling line system 

fails. There will also be an overlapping check on sampling line 

integrity when a line is replaced, since only one line will be 

changed at a time. 

The NO ANGMCC cooperative flask sampling network 

continued to provide whole air samples for the measurement of 

atmospheric CO2 and methane (CH4) concentrations. In 1988 

the network consisted of the 26 sites listed in Table 4.2. 

Provisional mean CO2 concentrations are also given in Table 

4.2. Sampling was begun at Ragged Point, Barbados, and 

sampling at Cosmos, Peru, was discontinued because of 

intractable logistical problems. 

The measurement of atmospheric carbon monoxide (CO) 

concentration was begun using samples collected in flasks 

equipped with T eflon O-ring stopcocks at a few selected 

network sites (see Section 4.1.5). Extensive field and laboratory 

testing have shown that T efl on O-ring stopcocks will be a 

suitable replacement for the greased ground-glass type currently 

in use. This is significant because the greased stopcocks are 

unacceptable for CO measurements. The problem o f frequent 

breakage of Te flon O-ring stopcocks has now been resolved. 

A new CO2 flask analysis apparatus was put into service in 

December 1988 . The previous analysis system, described by 

Komhyr et al. [1983], did not have the capacity for handling the 

large number of flasks that are currently being analyzed (more 

than 7000 samples in 1988). The analysis system is shown 

schematically in Figure 4.1. In general, 12 sample fl asks are 

connec ted by two-way solenoid valves to a central manifold. 

Four reference gases (W, X, Y, and Z) are also connected to the 

manifold so that the refe rence gases flow through the same 

analysis path as the flask samples. A diaphragm vacuum! 

pressure transfer pump pulls the air from the flasks or the 

reference gas cylinders and momentarily compresses the air into 

29 

T able 4.1. Prov isional Monthly and Annual Mean CO2 

Concentrations (ppm, Relative to Dry-Air X85 Mole 

Fraction Scale) from the 1988 Continuous Analyzer Data 

BRW MLO SMO SPO 

Jan. 354.87 350. 19 349.24 348.06 

Feb. 356.23 35 1.50 349.70 347.92 

March 356.56 352. 1 I 349.35 347.98 

April 357.40 353.51 350.27 348.18 

May 356.83 354. 16 349.63 348.28 

June 355.27 353.60 349.66 348.50 

July 348.43 352.61 349.94 348.89 

Aug. 343.10 350.32 349.81 349.33 

Sept. 345.87 348.81 348.94 349.59 

OCl. 350.59 348.96 349.26 349.70 

Nov. 354.28 350.09 349.72 349.53 

Dec. 357.86 351.32 350.58 349.23 

Annual 353.1 1 351.43 349.68 348.76 

Table 4.2. Provisional 1988 Annual Mean CO2 Concentrations 

From the Flask Network Sites 

Code Station CO, (ppm) 

ALT Alert, N.WT., Canada 352.8 

AMS Amsterdam Island IJ 

ASC Ascencion Island 350.3 

AVI SL Croix, Virgin Islands 351.3 

AZR Terceira Island, Azores 351.4 

BRW Barrow, Alaska 353.2 

CBA Cold Bay, Alaska 352.1 

CGO Cape Grim, Tasmania 348.8 

CHR Christmas Island 351.1 

CMO Cape Meares, Oregon 352.5 

GMI Guam, Mariana Islands 351.9 

HBA HaUey Bay, Antarctica IJ 

KEY Key Biscayne, Florida 352.6 

KUM Cape Kumukahi, Hawaii 351.3 

MBC Mould Bay, Canada 352.7 

MID Midway Island 352.8 

MLO Mauna Loa, Hawaii 35 1.1 

NWR Niwot Ridge, Colomdo 351.8 

PSA Palmer Station, Antarctica 349.4 

RPB Ragged Point, Barbados 351.4 

SEY Mahe Island, SeycheUes 350.2 

SGI South Georgia Island I J 

SHM Shemya Island, Alaska 352.5 

SMO American Samoa 350.0 

SPO South Pole, Antarctica 348.8 

STM Station M 352.1 

Square brackets indicate insufficient data to calculate an nual mean. 
",",w =:::::~~ . 

o

• ~ F~······"·"""~:::" . 0 

<> :::~I=:> h -.. _... c .... , 'K ... .::~:..-_=r~T:lI! 

~r':: -, .• "' M-,,,,_lJIE_L_". _ I I 

In ... 

Fig. 4.1. The new semiaUlomalic flask analysis apparalUs. 

a small volume between the pump and the outlct solenoid valve 

(V 0\1\). The solenoid valve is then opened, and the sample is 

pushed through a particle filter, a mass flow controllcr. a cold 

trap for removing water vapor. and into the CO2 NDJR analyzer. 

The response of the analyzer is measured with a digital 

voltmeter, and the results arc transferred to the computer. 

Timing and sequencing of events arc controlled by the computer. 

which sends commands to a relay switching unit for activating 

devices. A two-stage direct-drive vacuum pump evacuates the 

system between samples when the two solenoid valves VI and 

V2 are open. 

For the analysis of flask samples. two reference gases, 

approximately 10 ppm apart in concentration, are chosen from 

the four available to bracket the expected concentrations of the 

flask samples. These gases are analyzed, followed by 12 flask 

samples. The two reference gases are again analyzed to allow 

correction for drift and sensitivity changes in the analyzer. 

Results of tests perfonncd on the system show that under 

optimum conditions, the short-tenn (l day) precision of the 

analysis system is better than 0.05 ppm. Longer tenn precision 

over several months, based on lest flasks filled from a calibrated 

compressed air tank, is about 0.07 ppm. This value includes 

uncertainties due to filling and analyzing flasks, as well as to 

uncertainties in the calibration system used for assigning CO2 

concentrations to reference gas tanks. 

The new CO2 flask analysis system has a number of advantages over the analysis system used previously by GMCC. The 

system has been configured to analyze up to 180 flasks per 

analysis day. In practice, about 100 to 120 are analyzed, which 

takes approximately 6 hours to complete. The old system had a 

capacity of 60 flasks per day, so fewer analysis days will now be 

required to analyze the same number of flasks. A slight decrease 

in the amount of reference gas used is expected, since more 

flasks arc analyzed for each reference gas sample. Extensive 

tests with flasks filled from calibrated cylinders showed that no 

systematic offsets are present. It is expected that the new system 

will be able to handle, for several years, the ever-increasing 

number of samples required for detennining the global distribution of CO2 concentration in the aunosphere. 

30 

Concentrations of atmospheric CO2 in 1988 showed a larger 

than nonnal increase from the previous year. Annual means of 

CO2 concentration from the flask sampling network for 

1981-1988 are shown as a function of sine of latitude in Figure 

4.2. A relatively large increase from 1987 to 1988 can be seen. 

The average difference of annual means from 1987 to 1988 for 

20 sites was 2.6 ppm. This compares with an average of about 

1.5 ppm yrl for the 7 previous years. It also appears that the 

magnitude of the North Pole-la-South Pole difference in CO2 

concentration is larger in 1988 than in the prior 7 years. This is 

seen more clearly in Figure 4.3, which shows the latitudinal 

gradient for 1988 along with the average gradient for 1981-1987. 

The curves are third.degree polynomials fitted to the annual 

means; both curves are forced through 0 at the South Pole. The 

North Pole-to-South Pole difference was 3.7 ppm for 1988, 

compared with an average of2.8 ppm for 1981 -1987. This result 

implies either a larger source/smaller sink of CO2 in the northern 

hemisphere, a larger sink/smaller source of CO2 in the southern 

hemisphere, or a combination of the two. The first of these two 

possibilities is much more likely, since the anomalously high 

growth rate from 1987 to 1988 suggests an increased source 

rather than a smaller sink. Model studies of CO2 transport in the 

atmosphere are required to determine more precisely the cause of 

the large latitudinal gradient in 1988. 

90"S j. j j " j 

3410· I ! .. ~ ........ -... . 339-

~-- 33B[ 

L-~ __ ~ ____ -L ____ ~ ____ ~ 

-1 - . 5 0 .5 

SINCLATITUOE) 

Fig. 4.2. Annual mean CO2 roncollrations vs. latitude for 1981 (bouom) 

through 1988 (top) nask network data . The vertical lines represent the I· 

(J statistical uncertainty of the annual mean, as described by Conway el 

at. [1988). The curves arc cubic splines fitted to the data. 
E 

a. 

a. 

N 

o 

u 

3 

1988 

1981-1987 

, ,I 

.. ( 

Jili . 

_5 

5 I N (LATI TUDE ) 

I 1 

1 

, 

, 

I Ii 

-1-- -j 

, I, 

Fig. 4.3. A comparison of (he 1988 CO2 latitude gradient (top), 

dClcnnineci from n:lsk nClwork dal:l, with the mean gradient for 

1981-1987 (bottom). The curves are lhird·degree polynomials fiued 10 

the means; both curves are forced through 0 at the South Pole. 

The global CO2 growlh rate was determined by averaging the 

growth rates. weighted by latitude, from each of the flask net· 

work stations. The result is shown in Figure 4.4. A maximum in 

the growth rate of close to 3 ppm yrl occurred in late 1987, and 

1988 had a mean growth rate greatre than 2 ppm Yf'I. Growth 

rates for individual sites ranged from 2.0 to 3.9 ppm ytl. This 

peak in the growth rate is associated with the ENSO event in 

1987. The pattern of the growth rate variation in 1987-1988 is 

Fig. 4.4. The globa1ly averaged CO2 growth rate detennined from the 

flask network data for 1981-1 988. 

31 

consistent with previous ENSO events, in which high CO2 

growth rates followed minima in the Southern Oscillation 

Index by approximately 6 months, and the CO2 growtl! rate 

was correlated with sea surface temperatures (see, for 

example Bacastow. 1976; Komhyr e/ al., 1985; ElijoH ana 

Angell. 1987; Conway et al., 1988; and Thonjng el al.. 1989). 

Figure 4.4 also shows a peak in the growth rate in 1983. 

following the strong ENSO event of 1982. Preliminary 

results from 1989 show a return to more typical growth rates 

of about 1.5 ppm yrl. 

4.1.2. FLASK SAMPLE MEnlAt-;'[ MEASURE~{ENTS 

The program to measure the global distribution of atmospheric 

CH4 from flask samples collected at sites in the NOANGMCC 

cooperative fl ask sampling network continued in 1988. Results 

from this program for the calendar years 1984-1988 arc 

summari zed in me three-dimensional (3-D) representation shown 

as Figure 4.5. The way in which data from the individual sites 

arc treated in order to generate Figure 4.5 is described by Steele 

et at. [1987]. Data from the high-altitude sites of MLO and 

Niwot Ridge are not used in Figure 4.5. The globally averaged 

linear growth rate of atmospheric CH4 over the period May 1983 

to December 1988 is 12.24 ± 0.08 ppbyr·l . 

A significant improvement was implemented during the year 

with the installation of a fully automated system for the analysis 

of flask samples. Up to eight nasks at a time may be mounted on 

a carousel that is computer controlled. Each flask is analyzed in 

tum. and a sample of calibration gas is analyzed between each 

flask aliquol. Once analysis is initialed, me system will run 

unattended for about 4 hours. thus making flask analysis a less 

labor-intensive activity than it was previously. 

In addition to the nask samples obtained from the sites in the 

Oask sampling network. many fl ask air samples have been 

collccted aboard ships and also analyzed for CH4. The shipboard 

data se t was treated as an independent record in order to compare 

it with the data obtained from the network sites, by using the 3-D 

representation shown in Figure 4.5. The sample date and latitude 

of each shipboard nask sample were used to perform a straightforward interpolation on me 3-D surface in Figure 4.5 to obtain 

the CH4 concentration at the same date and latitude as each 

Fig. 4.5. Three·dimensiona1 representation of atmospheric CII4 in the 

marine boundary layer for 1984-1988. Grid spacing is to" in latitude and 

0.5 months in time. The anow indicates the position of the equator. 
shipboard flask sample. This was done for all flask samples 

taken on ships between May 1983 and December 1988. The 

result of the comparison is shown in Figure 4.6, where .o.CH4 

(shipboard CH4 - interpolated network CH4 ) is ploued against 

the latitude of the shipboard flask. It is clear that the overall 

comparison is very good; the mean value of .6CH4 is -0.06 ppb 

(0' = 13.92 ppb). The degree of scatter in the results for the 

southern hemisphere, particularly south of 10-S, is noticeably 

less than that for the northern hemisphere. This is consistent with 

observations of less scatter in the records of the southern 

hemisphere network sites [Steele et al., 1987]. The good 

agreement indicated in Figure 4.6 provides further proof Lhat Lhe 

current flask sampling network yields a realistic description of 

atmospheric CH4 in the marine boundary layer. In addition, since 

most of Lhe shipboard flask samples have been collected by using 

evacuated 3·L flasks fitted wi!.h an O-ring stopcock, they provide 

a useful check on the sampling procedures and the 0.5-L 

pressurized flasks used at most of the network sites. 

4.1.3. IN·SITU METIlANEMEASUREM8HS AT MLO 

These measurements continued during 1988. Some minor 

technical problems were experienced, but quick remedies kept 

data losses to a minimum. The data were edited to flag those 

periods when the gas chromatographic system was not functioning satisfactorily, then daily average concentrations were 

calculated. The results for 1987 and 1988 arc shown in Figure 

4.7. Note that at this stage, no data selection has been applied. 

The daily average data continue to show the types of flucruations 

thal have been noticed in earlier versions of these results. A 

thorough analysis of these variations is currently under way. 

Since flask air samples are routinely collected at MLO each 

week and analyzed for CH4 at the Boulder laboratory, we have an 

opportunity to compare the in-situ data with the flask results. In 

Figure 4.8 the flask sample data are plotted versus the hourly 

average in-situ CH4 value for the hour during which the flask 

sample was collected. It is clear that during 1987 and 1988 

agreement between the flask and in·situ measurements of CH4 at 

M LO was excellent. 

4.1.4. L'i-SITU METIlANE MEASUREM.E\"TS AT BRW 

This program continued through 1988. A major breakdown of 

the system occurred in June when both of the internal valves of 

the gas chromatograph failed. They were promptly replaced, 

resulting in a loss of only 10 days of data in June and 10 days in 

july. At the time of !.his repair, the gas chromatographic data 

system was also upgraded significantly. New ambient air intake 

lines that run from the observatory building to the top of the 

metcorological tower were installed. Consequently the 

chromatograph was working nonnally during the period of the 

ABLE-3A experiment, part of which was carried out in the 

vicinity of BRW in July (see Section 4.2.2). 

Considerable effort has been devoted to the development of 

robust procedures for the processing of the gas chromatographic 

CH4 data. The first and most critical need was for an objective 

computer algorithm to be applied to the raw data (i.e., peak areas, 

retention times, etc.) to assess the instrumental pcrfonnance. 

32 

o 

w 

- 90 

" 12 1 1'1(0 ..... /· -0 .60 

1'1("'. -0.06 

!I.O. 13.92 

A.O. 10. 11 

-60 

.... 

-]0 0 ]0 60 90 

'LAT ITUDE 

Fig. 4.6. Comparison between aunospheric CH4 values measured in flask 

samples colJected onboard ships and the CH4 values illlerp:>latcd for the 

same date and latitude from the 3-D surface shown in Figure 4.5; ACH4 

is shipboard CH4 minus interpolated network CIJ4 (see text). Values of 

.6CH4 are ploued at the latitude of the shipboard sample. 

:.\:!J':! ,-OJ 20n i 55:, 

, 

'(.00 L....._'"--'--'-"""'----'-'- .; f I.' ~ '.' J J 1\ .•. SOIl :-":c"::-'-:'~ 0 J f ~-M " !.\ J J II SOl! :J 

l?bl i ,)6e 

Fig. 4.7. DaiJy average CII4 concentrations at MLO for 1987 and 1988. 

The gaps in the record are due \0 instrument malfunctions. 

This has been achicved and allows for ready identification of 

those periods when the chromatograph was not functioning 

satisfactorily. The objectivc algorithm was assessed by carrying 

out an intensive comparison between the results of its decisions 

and those from a subjective evaluation of the chromatographic 

data. The effect of this objective algorithm on the in-situ CH4 

data obtained at BRW can be seen by comparing the first two 

panels of Figure 4.9. The first panel shows all of the CH4 

concentrations obtained from the system, and the second panel 

shows only those values obtained when the system was judged 10 

be operating satisfactorily. The most significant feature of the 

second panel is the absence of the large downward "spikes" in 

concentration. 
Mauna Loa 19N ISSW 

17413 

17213 

.0 

"-

"- 171313 

.,. 

I 16813 

u 

'" " 16613 

• 

"- 16413 

1620 

162016413 16613 16813 17130 17213 1748 

In S i tu CH4 (ppb) 

Fig. 4.8. Scatter plO!. of the alJT10spheric CH" concentration at MLO 

found from flask samples vs. the corresponding hourly-average in·situ 

CIf" concentration at MLO. The period covered by this comparison is 

April 1987 to December 1988. The dashed line is the 1:1 line representing perfect agreement between the two types of measurements. 

Furthcr assessments of the BRW in-silu CH4 data were carried 

out with the aid of the MUSIC software package developed by 

the Carbon Cycle Group for use on Hewlen-Packard work 

stations. Extensive modifications and improvements to this 

package have been made. The third panel of Figure 4.9 shows 

the result of the application of this package to 3 years of in situ 

data. Whereas the second panel shows all of the acceptable data, 

the third shows only those data obtained when both the hourly 

average wind speed was greater than 3 m S·I and the hourly 

average wind direction was in the sector 20'-110' . These 

meteorological constraints were applied for both the current and 

preceding hour (i.e., for a CH" concentration in any l-h period 10 

be accepted, the meteorological constraints must be satisfied for 

both that hour and the preceding one). The effect of this 

part icular choice of constraints to "select" the data is quite 

dramatic, indicating that much of the observed shorH errn 

variability of CH4 at BRW is associated with local human 

activities to the south and west of the observatory site. 

4.1.5. FLASK S/\~lPLE CARBON MOSOXlDE MEASURD.[E~TS 

A program to measure the global variations of atmospheric 

CO concentration was begun in 1988. The activities of this 

project during 1988 were to (l) assemble an analytical system 

capable of making precise measurements or co, (2) evaluate the 

stability of various flask types with respect to CO, (3) prepare 

gravimetric standards as the basis for an absolute CO concentration scale, and (4) begin measuring CO in Dask samples collected 

at GMCC sites. 

33 

, .. ~. II ~, :~ I . I' .: I ! i " Q: :::J ; 

I;i ~ ,. 

! ' 

:5 ~:J I j' . 

f ti ~ • " ;) 0 

, . ,:.;" 

-----_ .. ,- -. 

''''I I~~- '~-'~I-i~ -'-l'-' 

",,: , I' I 'I 

~, lH~J\U~1 ~ Ul~ ., -_.-.. _-,--.---- . . -- --- , 

: : ::; . 

~ -

.~:: -

j 

Fig. 4.9. In·situ hourly-average CII" measurements at llRW for 3 yea rs, 

1986·1988. -me top panel shows all the data. The second panel shows 

the acceptable dala after the application of an objective algorithm 

designed to identify periods of time when the gas chroma log raph was not 

functioning satisfa ctorily. The third panel shows the data "selccted" for 

the clean·air sector (see lext). 

The analytical system was developed using a gas 

chromatograph equipped with a Trace Analytical Reduction Gas 

Detector that measures CO by a mercuric oxide reduction 

technique. Gas sampling is controlled by a Hewlett-Packard 

integrator, along with an interface loop and a sample event 

controller. Precision at 100 ppb is typically ±O.5%. Cylinders of 

chemically dried air collected at Niwot Ridge, Colorado, were 

used as working standards. The CO content of this air was 

determined by calibration against GMCC gravimetric standards 

(described later in this section). 
The geographical coverage offered by the GMCC fl ask 

network can be used for CO measurements only if a type of fl ask 

is found in whjch CO concentrations do not change over time. 

Currently, air samples collected at GMCC flask network sites are 

not routinely dried. Laboratory tests were performed to evaluate 

the stability of various metal and glass flasks filled with both wet 

and dry naNral air. These tests showed that dry air in fl asks was 

more stable than wet air, and that samples in glass fl asks were 

more stable than in metal. Glass flasks with Teflon O-rings were 

found to be the most suitable for measurement of CO in undried 

::liT samples. Carbon monoxide concentration was stable to 

within I ppb for storage periods of up to 2 weeks in O.5-L flasks, 

and up to 6 weeks in 3-L flasks. However. samples in glass 

flasks must be protccted from exposure to sunlight because CO is 

known to be produced during the photochemical oxidation of 

some organic compounds. Flasks exposed to direct sunlight for 

even a few minutes have exhibited increased CO concentrations. 

In collaboration with the GMCC Nitrous Oxide and Halocarbons Group. the Carbon Cycle Group began preparing 

gravimetri c standards to define an absolute CO calibration scale. 

Experiments had shown that 0.8 m3 aluminum cylinders 

purchased fTom Scott-Marrin Inc., were stable for CO to within 

1 %. for at least 6 months. These cylinders were used to prepare a 

250-ppm mole fraction CO standard. From this parent, three 

daughter-standards were made in the concentration range found 

in the remote background troposphere: 45.22, 110.8, and 189.2 

ppb. Based on these three standards. a preliminary relationship 

of area response versus CO concentration was defined (Figure 

4.10). The CO concentrations reported here are referenced to 

these standards. 

Air samples collected in the boundary layer. in O.5-L fl asks 

fitted with Teflon O-rings, were analyzed for CO as part of the 

ABLE-3A mission in July 1988 (see Section 4.2.2.). In October, 

air sampling in Teflon O-ring 0.5-L flasks was begun at BRW as 

part of the weekly fl ask sampling program for carbon cycle 

gases. Sample takers were advised to avoid exposing the fl asks 

to sunlight by keeping the p3 sampling units closed and by 

keeping the flasks in their containers except when filling them. 

In fall 1988, weekly sampling in Teflon O-ring O.5-L flasks was 

also initiated at SMO. 

Preliminary CO concentrations at BRW (Figure 4.11) show a 

strong seasonal variation. with CO ranging from 85 to 160 ppb 

(GMCC concentration scale). The lowest CO levels were 

observed in July and the highest were in December. This 

relatively smooth increase in CO concentration from SlUTlmcr to 

winter is similar to that observed in previous years at BRW 

[Rasmussen and Khalil, 1982]. In conlrasl, the CO concentrations at SMO show more scatter from week to week. In addition. 

concenttations at SMO fall into a much narrower range than at 

BRW; CO levels were typically between 75 and 100 ppb (Figure 

4.11). The apparent attenuation of seasonal variation at SMO 

compared with BRW is believed to renect such factors as the 

smaller variation in seasonal solar radiation intensities at SMO 

compared to BRW, and stronger anthropogenic influences at 

BRW in the winter. 

v 

0 

~ 

• ~ 

c 

0 

a. 

~ 

• cr 

0 

• 4' 

0 

u 

400 

350 

300 

250 

200 

150 

100 

50 

0 

0 

Y = -15.3 + 1.801X r = 1.000 

25 50 75 100 125 150 175 200 225 

CO Concentration (ppb) 

Fig. 4.10. Gas chromatographic peak area rc.sponse vs. concentration for 

three GMCC gravimetrically prepared CO standards. 

34 

U 

u 

'-' " 

.6 

a. 

~ 

c 

.2 

~ c 

• u 

c 

0 

U 

0 

u 

200 

175 

150 

125 

100 

75 

50 

25 

0 

0 

= BRW = SfAO 

2 3 5 6 7 8 9 10 1 I 12 

Month of Yeor (1988) 

Fig.4.11. Flask sample CO measurements for BRW and SMO during 

1988. Each point represents the average of several measurements of a 

single flask sample. The l-cr uncertainty is shol,\'J1 when it is larger than 

the point. 

4.2. SPECIAL PROJECfS 

4.2.1. Sl-DPBOARD AIR SA~{PLING: OPERATION PACIFlC AIR 

This shipboard flask sampling project, begun on December 

14, 1986, COnlinue<! through 1988; 12 voyages of the Southland 

Slar were completed between Los Angeles and Auck1and, New 

Zealand. The 358 samples collected in 3-L evacuated flasks 

were analyzed for CO2 concentration. One sample from each 

pair was analyzed for CH4. In an attempt to determine how well 

this series of samples collected in 5- latitude bands at 3-week 

intervals characterizes Pacific open-ocean background conditions, a project to measure atmospheric CO2 continuously, in situ, 

was carried out on voyage 159 during July 1988. 
A Siemens ULTRAMAT-3 infrared analyzer. programmable 

switching unit, stripchart recorder, magnetic tape data logger, and 

gas handling system were installed aboard the Southland Star. 

Air lines were sb1Jng forward to both the starboard and port 

bridge wings of the navigation bridge. The vessel sailed from 

Terminal Island, California, on July 10 and arrived at Auckland 

on July 24. Continuous measurements of aunospheric CO2 were 

made throughout the voyage: 50 minutes of ambient air and 5 

minutes each of two reference gases every hour. The hourly 

average concentrations arc plolted versus latitude in Figure 4.12. 

The regular flask sampling routine was followed throughout 

the voyage by the ship's deck officers, who collected pairs of 

samples every 5" of latitude. A member of the Carbon Cycle 

Group participated in all the flask sampling on this voyage, 

observing the technique and providing suggestions for improvement when appropriate. In several instances, ncar-simultaneous 

samples were collected on the forecastle deck (bow) of the vessel 

while the deck officers sampled air from the usual bridge 

locations. 

Nineteen pairs of samples were collected. The pair difference 

was less than 0.1 ppm for 14 pairs and less than 0.3 ppm for 5 

pairs. The difference between the flask samples and the infrared 

analyzcr continuous record for the hour when the sample was 

collected ranges from -0.7 1 to +0.84 ppm. The average 

difference is +0.30 ppm (0 = 0.36), the flask values being higher 

than the continuous record. These preliminary (pending final 

reference gas calibration) results support the concept of a 

shipboard flask sampling program. Careful collection of flask 

samples by ship personnel will provide better resolution of tlle 

COl and CH4 latitude gradiems over lhe Pacific Ocean lhan is 

possible from the land-based flask network. 

" ~ 

~ 

~ 

0 

;::: 

~ 

~ :laO ~ 

~ 

w 

u 

z 

0 

u 

.. 

0 

u 

3·15 

SOU TIILAND STAR JULY t986 

\ 

CONTINUOUS .. 1 

FLASKS 01 

. , ~ ,:~\~:.,.r 

. L 

-40 -30 -20 -10 

, , o 10 20 

LATITUDE 

-

30 '0 

Fig. 4.12. Continuous analyzer and flask sample data vs. latitude from 

voyage 159 of the MJV Soulhland Slar during July 1988. The plus 

symbols (+) represent I-h averages of continuous analY7.cr data, and the 

circles (0) represent averages of flask pairs. Data associated with 

instrumental problems were edited from the plot. 

35 

4.2.2. ABLE-3A MISSlo" 

During July and August the NASA GTE program carried out 

the ABLE-3A mission. The NASA Electra aircraft was 

extensively instrumented to make airborne observations of 

aunospheric properties, and a ground measurement site was set 

up within a remote rundra ecosystem near Bethel, Alaska 

(llarrissand Wofsy, 1989]. Several of the aircraft nights were in 

the vicinity of BRW. One of the objectives during ABLE-3A 

was to compare, under field conditions, some different techniques for measuring the major atmospheric carbon containing 

trace species. On the NASA Electra, a fast-response tunable 

diode laser insb1Jment was operated to provide simultaneous 

measurements of CH4 and CO [Sachse et al., 1989), while an 

NDIR analyzer was used for CO2 measurements [Wofsy el af., 

1988]. On several flights in the vicinity of RRW, the Carbon 

Cycle Group collected approximately 170 flask air samples that 

were returned to Boulder for analysis of CO2, CH4, and CO. To 

provide the best possible chances for a successful intercomparison experiment, NOANGMCC supplied the other participants in the experiment with tanks of calibration air. 

Preliminary comparisons of the onboard and nask measurements 

indicate excellent agreement between the different techniques 

[Sachse et al .. 1989J. 

4.3. REFERE:'-;CES 

BacaSlow, R.B., Modulation of atmospheric carbon dioxide by the 

Southern Oscillation, Nalure. 261, 116·11 8, 1976. 

Conway. T.J .. P.P. Tam, LS. Waterman, K.W. 'noning, K.A. ~aurie, 

and R.II. Gammon, Atmospheric carbon dioxide measu rements in the 

remote globaitroposphere, 1981 · 1984, Telfus, 40B, 81-115, 1988. 

Elliott, W.P .. and J.K. Angell, On the relation between atmospheric CO2 

and equatorial sea·surface temperature, Telfus, 398. 171-183. 1987. 

lIarriss, R.C., and S.c. Wofsy, The Arctic Boundary Layer Expedition 

(ABLE·3A). £05. 70. 282.1989. 

Komhyr. W.O., LS. Waterman. and W.R. Taylor, Semiautomatic 

nondispcrsive infrared analyzer apparatus ror COl air sample 

analyses, 1. Geophys. Res .. 88, 1315·1322, 1983. 

Komhyr, W.O., R.B. Gammon, T.B. Harris, L.S. Waterman, TJ. 

Conway, W.R. Taylor. and K.W. Thoning, Global atmospheric CO2 

distribution and variations from 1968·82 ;\"OAA/GYfCC CO2 nask 

sample data, J. Geophys. Res., 90 , 5567·5596, 1985. 

Rasmussen. R.A .. and Yf.A.K. KahliJ, Atmospheric trace gases and Arctic 

haze at BRW, in Geophysical Moniloring lor Climatic Change, No. 

10: Swnmary Reporl 1981, B.A. Bodhaine and J.M. liarTis (cds.), 

i\OAA Air Resources Laboratory, Boulder, CO, 1982. 

Sachse, G.W., K.B. Bartlctt, R.C. ll arriss, G.r:. ll ill, L.O. Wadc, L.G. 

Burney, J.E. Collins, and L.P. Steele, Airborne measurements of 

methane and carbon monoxide during ABLE·3A, £OS. 70, 282, 

1989. 

Steele, L.P., PJ. Fraser, R.A. Rasmussen, M.A.K. Khalil, TJ. Conway, 

A.l. Crawrord, R.H. Gammon, K.A. Yfasa rie. and K.W. Thoning. The 

global distribution of methane in the troposphere, J. Almos. Chern .• 5. 

125·171.1987. 

'moning. K.W., P.P. Tans, and W.D. Komhyr. Atmospheric carbon 

dioxide at :\-launa Loa Observatory. 2. Analysis of the j\OAA 

G:\1CC data, 1974-1985, J. Geophys. Res., 94. 8549·8565, 1989. 

Wo(sy, S.c., R.C. Harriss, and W.A. Kaplan. Carbon dioxide in the 

atmosphere over the Amaron basin, 1. GeQphys. Res., 93, 1377·1387, 

1988. 
5. Ozone Group 

W. D. KOMHYR (Editor). S . J. OL notAl'S. R. D . GRASS .. R. D. EVANS. A,,'iD R. K. LEONARD 

5. 1. CON1ThuThG PROGRA,,"IS 

5. 1.1. T OTALOZOl"l'E OnsERvAllo:-:S 

Routine total 0 3 observations with Dobson 0) spectraphotometers were continued in 1988 at four GMCC stations, 

four foreign cooperative stations, three domestic cooperative 

stations, four NWS stations, and GMCC headquarters in 

Boulder. Table 5.1 lists the 16 stations, observing time periods 

for which data are available, instrument numbers, and agencies 

responsible for making the observations. Table 5.2 lists 

provisional monthly mean total 0 ) amounts for 1988. 

The year was unusual in that poleward transport of 0) in the 

southern hemisphere from the tropical stratospheric 0) source 

region, during the second half of the year, was stronger than 

nannaL 0) values at SMO reverted to those last observed Lhcre 

in the mid-1970s. 0 3 deplction in Antarctica was substantially 

less severe than it had been in recent years; polar vortex 

breakdown occurred relatively early, as did 0) recovery. The 

mean spa total 0) for October 15-3 1 was 25 1 D.U. (Figure 

5.1), which is comparable with total 0) arnOlmts observed at 

spa during the same period in 1966. 1969. 1975. and 1977. 

TABLE 5.1. U.S. Dobson Ozone Spectrophotometer Station Network for 1988 

Station Period of Record Instrument No. Agency 

Bismarck, i\TI Jan. I, 1963-present 33 NOAA 

Caribou, ME Jan. I, 1963-present 34 NOAA 

WalJops Is., VA July I, 1%7-present 38 NOAA; NASA 

SMO Dec. 19, 1975-prcsent 42 NOAA 

Tall ahassee, FL May 2, 1964·prcsent 58 NOAA; Rorida State Univ. 

Boulder, CO Sept. I, 1966-prcsent 61 NOAA 

Poker Flat, AK March 6, 1984·present 63 NOAA; Univ. of Alaska 

Lauder, New Zealand Jan. 29, 1987-present 72 NOAA; DSlR 

MLO Jan. 2, 1964-present 76 NOAA 

NashviUe, TN Jan. 2, 1963-present 79 NOAA 

Perth, Australia July 30, 1984-present 81 NOAA; Auslralian Bureau Meteorology 

SPO Nov. 17, 1961-prcsent 82 NOAA 

Haute Provence, France Sept. 2, 1983-present 85 KOAA; C1\TRS 

Huancayo, Peru Feb. 14, 1964-present 87 NOAA; IG? 

BRW June 6, 1986-present 91 NOAA 

Fresno, CA June 22, 1983-present 94 NOAA 

TABLE 5.2. Provisional 1988 Monthly Mean Total Ozone Amounts (m-aon-cm) 

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

Bismarck, NO 342 350 380 360 355 316 324 309 295 283 314 3 15 

Caribou, ME 362 391 398 385 372 384 336 330 3 19 332 304 372 

Wallops Is., VA 316 327 352 369 369 356 336 314 303 315 281 303 

SMO 255 256 251 252 253 268 270 269 272 274 268 262 

Tallahassee, FL 292 290 295 325 273 285 272 291 

Boulder, CO 306 321 357 327 339 311 303 295 297 272 286 306 

Poker Rat, AK 447 427 380 350 331 315 312 305 

Lauder, New Zealand 29 1 292 277 274 284 303 325 360 361 387 322 304 

MLO 229 241 265 279 288 276 276 266 259 266 261 253 

Nashville, TN 314 323 345 355 369 360 333 319 298 312 281 290 

Perth, Australia 283 282 271 275 282 289 307 325 328 325 312 296 

SPO 283 262 246 246 256 241 251 342 333 

Hau le Provence, France 329 345 364 369 362 360 326 320 313 285 280 321 

Huancayo, Peru 254 253 25 1 248 252 253 254 255 264 262 260 257 

BRW 468 447 399 353 330 310 338 

Fresno, CA 283 300 334 353 346 338 317 310 302 276 281 303 

36 
SOUTH POLE OCTOBER 15-3\ TOTAL OZONE 

"5 

e. 300 

w 

z 

o 

N 

o 

--' 

~ 200 

f2 

YEAR 

Fig.5.l. Mean October 15-31 South Pole, Antarctica, total 0 3 amounts 

for 196 1-1988, dctennined from Dobson spectrophotometer 

observations. 

5.1.2. VMKEHR OBSERVATIONS 

Vmkehr observations with Dobson 0 3 spectrophotometers 

were continued during 1988 in Boulder, Colorado (40"N, 

I05"W); Mauna Loa, Hawaii (20"N, 156"W); Haute Provence 

Observatory, France (44' N, 6' E); Poker Flat, Alaska (6S' N, 

14S'W); Perth, Austra1ia (32"5, 116"E); and Lauder, New 

Zealand (45 ·5, 169 QE). A total of 1458 usable 0] profiles were 

obtained. All provisional data have been archived at the WMO 

World Ozone Data Centre, ALmospheric Environment Service, 

Downsview, Canada. 

Vmkehr observations at Huancayo were not made during 

most of the year because of failure of the Huancayo instrument 

to operate in the automatic mode. Total 0 ] observations were 

continued manually, however. The International Affairs Office 

of NOAA helped arrange a visit to Boulder in June by the Chief 

of Meteorology and Electronics at the Huancayo Observatory. 

While in Boulder, he was !rained in operation and repair of the 

instrument. However, because he was unable to repair the 

automated instrument completely, a decision was made to 

abandon attempts at repair, and manual Umkehr observations 

were commenced in November 1988 . Operations at the 

observatory are being increasingly adversely affected by 

activities of the "Shining Path" guerilla armies. 

The Perth automated Dobson instrument malfunctioned in 

October when an optical wedge band broke. The instrument 

was recalibratcd relative to World Primary Standard Dobson 

Spectrophotometer no. 83 in November. 

5.1.3. DODSON SPECfROPHOTOMETER CALIBRATIONS 

GMCC continued its program of upgrading and calibrating 

Dobson 0 3 spcctrophotometers of the global Dobson instrument 

network. Instruments worked on are listed in Table 5.3. 

Calibrations were performed relative to Dobson sPCC lrO ~ 

photometer no. 83. 

37 

Table 5.3. Dobson Spectrophotometers Calibrated in 1988 

Country Station Instrument ~o. 

U.S.S.R. Leningrad 108 

U.S.S.R. Moscow 107 

Australia Penh 81 

New Zealand Lauder 72 

U.S.A. Bismarck 33 

U.S.A. Boulder (SPO) 80 

U.S.A. Boulder (Secondary Standa rd) 65 

Australia Melbourne (Regional Standard) 105 

Of the three domestic instruments calibrated, instrument no. 

80 was destined for shipment to SPO. to replace instrument no. 

82 that has been in use at the South Pole since 1984. lnstrument 

no. 65 was calibrated for use as a secondary standard. 

Instrument no. 33 remained in Bismarck. 

Preliminary calibration of U.S.S.R. secondary standard 

Dobson instrument no. 108 showed that 0 3 va1ues obtained with 

it agree with those of instrument no. 83 to ±0.15%. U.S.S.R. 

instrument no. 107 was modernized electronically, opitcally 

aligned, and calibrated for the first lime. 

In November-December 1988, the aUlomated Dobson 

instruments at Perth, Australia. and Lauder. New Zealand, were 

calibrated . Calibrations were performed in the total 0] and 

Umkehr modes. Recalibration of the Perth instrument was 

needed following repair of the instrument's optica1 wedge in 

October. The Lauder s~ctrophotometer was found to be in 

good calibration. 

5.1.4. YALIDATIOK OF TOMS Al\U SBVY SATELLITE O2O:'\E 

DATA AT MLO wrm Dos SO:\' SPEcrROPHOTO~{ETER No. 83 

Since 1979, when the TOMS and the SBUY 0] instruments 

were launched aboard the Nimbus-7 satell ite, calibration checks 

have been performed duri ng most years at MLO on World 

Primary Standard Dobson Instrument no. 83. The Dobson 

instrument tota1 03 data have been compared with the TOMS 

and SBUY overpass data as a check on the calibration drift of 

the satellite 0] sensors. Figure 5.2 shows the comparison 

results. Note that the ca1ibration drifts of the TOMS and SBUY 

instruments, caused by deterioration of a diffuser plate common 

to both instruments, are nonlinear and amount overall to about 

5% in 9 years. Satellite data for the comparisons were provided 

by NASA [see McPeters arul Komhyr, 1989). A similar 

calibration drift for the TOMS and SBVY satellite 0 ] sensors is 

indicated by data from 39 select stations of the global Dobson 

instrument network (Fleig et al., 1986]. The network 

instruments have been calibrated relative to instrument no. 83 

since the mid-to-late 1970s. 

The long-term 0] measurement precision of instrument no. 

83. has been maintained to within ±O.5% since 1962 [Komhyr et 

al.,1989a]. Instrument No. 83 data are presented in Figure 5.2 

on an absolute scale. indicating that when the satellite 0 3 
Year 

Fig. 5.2. Calibration drift of thc TOMS and SBUV satellite OJ 

inslrumcnts during 1979- 1988 relativc to World Primary Standard 

Dobson in strument No. 83, and relalive 10 39 stalions of the global 

Dobson spectrophotomctcr nctwork. 

instruments first began operating in 1979 the TOMS instrument 

measured total 0 ) amounts too high by 4% while the SBUV 

instrument measured 0) values too highly by 1 %. 

5.1.5. TROPOSPHERIC OZOl",'E 

Observations of 0) ncar the surface have been made for 15 

years at the GMCC observatory at BRW. Records approaching 

this length have been obtained at the other GMCC sites. In 

October 1988, as part of the AEROCE, a surface 0 ) monitoring 

program was begun in Bermuda. Installations are planned 

during 1989 for Barbados; Mace Head, Ireland; and Tennerife, 

Canary Islands. This network is designed to measure fluxes 

from the continental regions surrounding the North Atlantic to 

the ocean region. These sites arc more likely to record 

alterations in the background levels of 0 ). as a result of reactive 

nitrogen compounds emitted by human activity, than are the 

more remote GMCC sites. 

At BRW the marked summer and aurumn increases have 

continued (Figure 5.3) with a highly significant linear trend of 

1.39 ± 0.57% yrl. This is in contrast to the remainder of the 

year (not shown) when no change has been detected over the 

IS-year record. During the summer months sufficient solar 

insolation allows for 0 ) generation, if necessary precursor gases 

such as nitrogen oxides are present. Recent summertime aircraft 

measurements as part of the NASA ABLE-3A experiment 

indicate rather low reactive nitrogen amounts for Alaskan 

continental regions [Chen el ai., 1989] except during forest-fire 

related episodes. The 0 ) flux to the surface during this time of 

year is also large. Long-tenn changes in this flu x could also 

produce changes in the seasonal surface 0) amount. 

At MLO, surface 0) increases have been confined to the 

winter months, primarily January (Figure 5.3). Large 0) 

amounts were noted in late 1982 and early 1983 at the level of 

MLO (680 mb). The continuing series of ozonesonde 

measurements from Hilo show that although tropospheric values 

at the level of the observatory were high in 1983 relative to 

38 

• 

•• 

< 

.. 

~ 

»1 - NOV 

/'-, A 

\.19 i 0.51\ yr- I 

BARROW 

./'\ ~ ....,'"lY 

.A. 

V V 1.31 ! 1.00: ),r - I 

MAUll A LOA 

O-J-r 

~ co. 

SAMOA ~ - I -1.84 ! 1.251 yr 

0- J- r 

::::::.2 ~ C, V S 

SOUTH POLE -1.68 i 0.851 ),, 1 

70 11 12 13 H 15 76 17 ·78 79 80 8 1 82 63 61 8'!i as 87 68 69 

OATE 

Fig. 5.3. Annual surface 0) amounts for the Junc-Novcmbe r sca son at 

BRW, for the monlh of January at MLO. and for the DcccmberJanuary-Fcbruary season at SMO and SPO. The trends arc thc linear 

least-squares fit 10 the data. The uncertain ities are the 95% confidencc 

interval, based on a two-taiJed I test. 

subsequent years (Figure 5.4), upper tropospheric values (above 

300 mb) were much reduced. A similar pattern was seen in the 

spring of 1987 (Figure 5.5) in which 0) in the upper troposphere 

was much reduced. In both December-January-February 1983 

and March-April-May 1987 tropopause heights were higher than 

normal. In both cases this period is the minimum in the SOl, 

which is indicative of an El Nino event. During such an event, 

Pacific Ocean temperatures are above normal , and enhanced 

convection produces higher tropopauses in the region. This 

seems to be reflected in reduced 0 ) amounts in the upper 

lrOposphere. It is not clear, however, why the troposphere 

below aoout 8 km has above-normal 0) amounts under such 

conditions. Although tropospheric circulation patterns are 

altered during an EI Nino event (Quiroz, 1983], it is diffi cult to 

specify how such changes affect the 0 ) circulation at a 

particular location without detailed model calcul ations. 

At both SMO and SPO, there has been a significant decrease 

in the near-surface 0) concentration during the austral summer 

months (Figure 5.3). 1n both cases, this is the season of the 

minimum in the annua1 cycle. 

The minimum occurs during this season rather uniformly 

throughout the southern hemisphere at locations unaffected by 

local pollution sources. Under the very low NO" (NOz + NO) 

conditions that probably predominate throughout the southern 

hemisphere lower troJX>sphere, the oxidation of CH4 and CO 

produces a net loss of 0 ) ICrutzen, 1988]. Although no 

long-term changes of CO have been noted in the southern 

hemisphere (Fraser and Coram, 1988]. CH4 concentrations 
.0 

E 

100 

150 

200 

250 

300 

400 

500 

600 

700 

850 

1000 

, 1" 

.' " 

25 50 

, 

I 

HILO (200 N) 

OJF 

1983 

1985 _88 

Volume Mixing Ratio (ppb) 

16 

14 

12 

~ Ql 

10 1ii 

E 

.Q 

8 g 

6 

4 

2 

o 

125 

EO 

Ol 'w 

I 

Fig. 5.4. Season average (December-January-February) 0) proftle 

from owncsondes al Hila, Hawaii, for 1983 (solid curve) and 1985-88 

(dashed curve). The ® is the 1983 value measu red at MLO with the 

surface monitor. The 0 is the MLO data for 1985-88. The MLO data 

3 TC ploued at the approx.imate altitude of the observatory. 

.0 

E 

~ 

" V> 

V> 

., 

a: 

100 

150 

200 

250 

300 

400 

500 

600 

700 

850 

1000 

[ , I , 

, 

25 

, 

, 

I , 

I 

, 

, 

I 

\ 

\ 

I 

I 

I 

\ 

, / , , ,~ 

, 

. I • 

HILO (200 N) 

MAM 

1987 

1983 ~ 88 

100 

Volume Mixing Ratio (ppb) 

16 

14 

12 

~ Ql 

10 Q) 

E 

.Q 

8 ;g, 

6 

4 

2 

o 

125 

:c 

Ol 'w 

I 

Fig. 5.5. Season average (~arch-A pril·Yla y) 0) profile from 

ozonesondes at Hila , Hawaii, for 1987 (solid curve) and 1983-88 

(dashed curve). There were no observations in 1984. 

39 

have continued to risc [Bodhaine and Rosson, 19881 . The 

summer months, having abundant solar insolation and higher 

water vapor amounts. give greater OH concentrations [CrUlzen. 

1988]. nlis in rum should lead to lower 0 3 amounts lhrough the 

oxidation of CH4 • Determining whelher lhe gradual decline in 

summenime southern hemisphere 0 3 concentrations is related to 

lhe buildup in aunospheric CH4 requires additional modeling of 

this chemistry. 

5.1.6. Ozo:-''Esm.mE OBSERVA110~S 

ECC ozonesonde observations were continued at Boulder. 

Colorado. and Hilo, Hawaii; soundings were made at weekly 

intervals. Similar observations were made throughout the year 

at SPO, but at a frequency of one sounding every 2-3 days 

during lhe Antarctica springtime. 

As indicated earlier. 0 3 depletion in Antarctica during 

September and October 1988 was much less pronounced than in 

1987 [Komhyr el al., 1989b}. Figure 5.6 contrasts 0 3 and 

temperature profiles over SPO on October 12, 1987, and 

October 10, 1988, days during the 2 years when maximum 0 3 

depletions were observed at pressure aiLilUdes of 100-30 mb 

(centered at about 17 km). Note lhat in 1987 the 0 3 at 17 km 

was virtually completely depleted. whereas in 1988 the 

depletion amounted to only about 60%. Stratospheric 

temperatures colder than -78°C. at which polar stratospheric 

clouds occur. persisted in 1987 till the end of October. In 1988 

the temperatures became warmcr than -78°C about 2 weeks 

earlier. Rapid sLratospheric warming occurs atlhe time of polar 

vortex brcak<.!uwn an<.! the influx of 0rrich air into Antarctica 

from lower latitudes. In 1987. the winter and early spring 

Antarctica circumpolar vortex was of large areal extem. and 

SPO was situated approximately centrally wilhin it. In 1988 lhe 

vortex was much smaller. and its center during September and 

October was generally displaced from SPO in the direc tion of 

the Palmer Peninsula. 

5.1.7. STRATOSPllER1CWATER VAPOR 

With 8 years (1981 through 1988) of water vapor profiles in 

the stratosphere. it is possible to look for lhe longer tenn 

variations that might be suggested by the rising trend in CH" in 

the atmosphere. The photolysis of CH4 in lhc stratosphere is 

expected to be a major source of H20 vapor in this region. The 

avcrage growth rate in CH4 over the past several years is aoout 

0.012 ppmv yrl, based on observations at the GMCC nask 

sampling network [Bodhaine and Rosson, 1988]. If a similar 

increase is taking place in the stratosphere, then a maximum 

increase in H2

0 vapor of about 0.024 ppmv yrl might be 

expec tcd if alilhe CH4 was eventually photolyzed. 

At 50 mb (20 kIn) lhe seasonal variability of H20 vapor is 

small [Schnell and Rosson. 19871. making this an appropriate 

level to chc.ck for longer term changes. It is also a level that is 

usually attained in the balloon sounding and where instrument 

performance is good. Volwne mixing ratios at 50 mb for each 

successful sounding are shown in Figure 5.7. The trend line is a 

linear least-squares fit to the data. The trend and 95% 

confidence interval based on lhe two-tailed t test is 1.26 ± 0.67% 
o Z 0 II A G RAM 

SITE: SOUTH POLE 

DATE: 12 OCT 87 

1111(, 0201 Z 

lOTi1LO)' 11 7. 

SOU[)( [)): 160. 

C.'. ' .917 

L-__ ~I~"'~T:'==(C:C::':R=26=I:J::===============7~ 10-

,~~-4~---t~ ~O'I ATM-eN -]5 ]5-

I 0HH-+'-~-+-"~-; o:---l--=:o,"-<::-t--~*--f""",,:-f--l fO - a ]0-

JlOHH~--+'~--4C~~-+-----1e-~"-~~~/~-1 

• & ~ 

~ 

~ 

wsol~~-f~--+-~~~--4-----~~~-t,o,J4~~~~t4~--~~~~---t~~ 1 

<l: "; 

~ 5 

IS 500 

10 fDo 

.1 .2 10OO,L---~~ __ ~_~~J-____ L-__ ~ __ ~~ __ 

a 50 100 150 200 2'30 JOO -'0 -70 -so -]0 -10 10 "I PARTI AL PH[SSUR( or OlOtJ[ HlOI Tnf'[RIllUH[ I'CI 

(LLJl.J LD--'>-!L1L.11 

m 

L 

, 

10 

SClJTII r Olr. 

10 OCT no 0050 Z 

w20IH ~--~~~~~-1e----Ce-~"-1 

~ 

~ 

~ 

',I so I-\-~-li'c---

• 

~ 

lOa - " -' 

~,lII(1 r. OJ, 1!J7. 

c,r. : 

~ 

n 

5 

25-

- ;"0-

,.--~ '''- -

~ 

cP' '>-... 

">~D . ""-----------' . -...... ':iO 1M Isn ?on 2':.0 ]01) '.n · ... 0 -10 I II rWHIAL f'f1[SSUR( or OlOIl( Ulill rOIl'[I'UllURr: ('Ct JO 

Fig. 5.6. 0) and temperature prafLIes (solid curves) over South Pole, Anta rctica, on days in October 1987 and 1988 when maximum 0 3 depletions were 

observed between 100 and 30 mb. The dashed 0) curves arc August 24,1987, and August 21,1988, profiles obtained prior to the onset of 0) depiction 

processes. (The dashcd temperature curves represent standa rd almosphere temperatures.) 

40 
;-

< 

t 

o '.' 

~ 

~ 

'I .--=~= . '·~' ·~~~~~~'~=;~~~ z 

. 

" ... 

w " < 

~ 

~ 

" 

50MB 

" " 

BOULDER CO 

&1 IS I!S " .. Y[IlR 

Fig. 5.7. Water vapor volume mixing ratio (ppmv) at 50 mb from 

balloonbome frost-p::>inl hygrometer soundings at Boulder, Colorado. 

"Thc trend line is a linear least-squares fillO the data. 

+-~~~-C.~,~~.~,-r-.~,~-c.,-'--~~--~--~.-,-r-~--'--.. ~ 7 

DRTE 

Fig. 5.8. The smoothed water vapor volwne mixing ratio (ppmv) at 80 

mb at Boulder. Colorado (solid curve), and smoothed SOl (dashed 

curve). 

yrl. TItis is an increase of about 0.05 ppmv yrl, which is more 

lhan expected for CH4 increase. From Figure 5.7, it is clear that 

most of the trend can be attributed to the low values in 1981. 

The sensors used in 1981 and the frrst half of 1982 were 

calibrated at the Naval Research Laboratory in Washington, 

D.C. Since 1982, the sensors have been calibrated at a GMCC 

laboratory. The two laboratories' temperature measurement 

systems were intercompared and found to be in close agreement 

[Harris and Nickerson, 1984]. Unfortunately no sensors used 

during 1981-82 are still available to verify the earlier 

calibrations. 

At lower altitudes in the stratosphere, the seasonal variation 

dominates. The strong springtime minimum is thought to be 

related to the very cold tropopause temperatures in the tropical 

western Pacific and to subsequent poleward transport of this dry 

air [Brewer, 1949]. Meteorological variations on longe.r time 

scales such as those of the ENSO, which are centered in the 

tropical Pacific, might be renected in the lower stratospheric 

water vapor pattern at Boulder. In Figure 5.8 the smoothed 

41 

water vapor anomalies at 80 mb in Boulder are shown with the 

smoothed values of the SOl. The two ENSO events of 

1982-1983 and 1987 shown in the SOl are perhaps renected in 

above-average water amounts seen during this time at Boulder. 

H this relationship holds up over longer measurement periods, it 

suggests that during ENSO events, additional water vapor 

reaches the stratosphere. This might be the result of the 

enhanced convection associated with wanner ocean 

temperatures. Data from Washington, D.C., from 1964 to 1976 

suggests that a similar relationship held, although the 

year-to-year variations in water vapor are much larger than 

those at Boulder. 

5 .2. SPECIAL PROJECTS, OBSERVATIO:-/S 

L'IDICA TING POSSIDLE OZONE DESTRUCTION 

DURING TIlE A,'HARCI1C POLAR NIGHT 

Since the discovery of the springtime Antarctic 0) depletion, 

a great deal of attention has been given to processes related to 

aerosol formation and heterogeneous chemistry at low 

temperatures. Polar stratospheric clouds (PSCs) are frequent 

features of the southern winter atmosphere, and provide a site 

for heterogeneous reactions that lead to 0) destruction in the 

presence of sunlight. Models have been proposed for the 

formation of PSCs based on the condensation of HNO). 

An aerosollidar inslIllment from the University of Rome "La 

Sapienza," Physics Department, Rome, Italy, operated at SPO 

during the 1988 polar night, indicated the presence of PSCs 

[Fiocco el at., 1989]. 0 3 profile measurements, made quasisimultaneously with ECC sondes during June and July months, 

showed sharp 0) concentration minima in the vicinity of the 

PSCs. The correspondence between the aerosol layers and the 

0 ) minima is shown in Figure 5.9. which depi cts four haJrhour-average aerosol profiles for June 21-24 (all taken at about 

2230 UTC), and 0, and temperature profiles for June 23. 0255 

UTC. (For reference, Figure 5.9 also shows an average 0 ) 

profile derived from ozonesonde measurements made in June.) 

The 0) minima occur at about 14.5, 15.6 and 16.9 km. Less 

than a day later (curve c), intense stratifications at about 14.4, 

15.8, and 17.4 km were seen by lidar. 

Definitive information is unavailable for unambiguous 

interpretation of the results. The simultaneous presence of the 

0) and aerosol features may, however, be ascribed to several 

possible mechanisms: (I) Air masses with low 0) content and 

appreciable amounts of condensable ma.tter. possibly water, 

reach the SPO stratosphere, structured in thin (I-kIn) layers. No 

chemical interaction between the constituents is implied; the 

lower 0) amounts are related to the origin of the air masses. (2) 

Air masses carrying PSCs pass in and out of darkness through 

sun1it regions where photochemical 0 ) destruction may occur. 

Thus, 0) may also be destroyed in Antarctica during winter and 

not only during springtime. (3) 0) can be destroyed in the 

absence of sunlight through reaction with N02 to form N20 5 and 

then condensable HNO). However, this process is unlikely to 

occur at the magnitude implied by the measurements. (4) 0) is 

destroyed catalytically by reaction on the PSCs. 
18 0 

[ 

L 

[ 

, 

[ 

E 

16t-

=: f 

" '- "C 

3 

;;: 14 [-

'--'--__ -'-___ ---"-_-/ f-----'--_-'-...J..JL-.-112 

50 100 150 -90 -80 -70 - 60 

03 Partial pressure Inbarl Temperature (OC) 

Fig. 5.9. (a)·(d) Aerosol backscauering profiles for June 21-24, respectively. derived frorn averaged half-hour lidar observations made at about 2230 

UTe, (~) 0) panial pressure proftle and (f) temperature prof tie. for June 23. 0255 UTe (solid curves). The dashed curve is the average 0) profile derived 

from five ECC ozonesonde measurements made in June. 

5.3. REFERENCES 

Bodhaine. S.H., and R.M. Rosson (Eds.), Geophysical Moniloring for 

Climalic Chaflge No. 15, SlVnnIQry Reporl JgB7, 110 pp., NOAA 

Environmental Research Laboratories, Boulder, CO, 1988. 

Brewer, A.W., Evidence for a world circulation provided by 

measurement of helium and water vapor in the stratosphere, Q. 1 . R. 

Me/eorol. Soc., 75, 351-363,1949. 

Chen, G., S. Sandholm, 1. Schendel, D. Davis, and 1. Bradshaw, High 

latilUde distributions of reactive odd-nitrogen components NO, N02, 

and NOy observed during GTE/ABLE-3A, EOS, 70, 291, 1989. 

Crutzen, PJ., Tropospheric ozone: An Overview, in Tropospheric 

Ozone, edited by I.S.A. Isaksen, pp. 3-32, O. Reidel, Dortrecht, 

1988. 

Fiocco, G., W.O. Komhyr, and O. Fui, Is ozone destroyed during the 

Antarctic polar night in the presence of polar stratospheric clouds? 

Nature. 341,426-427, 1989. 

Fleig, AJ., P.K. Bhartia, C.G. Wellemeyer, and O.S. Silberste in , An 

assessment of long term drift in the SBUV tota l ozone data based on 

comparison with the Dobson network, Geophys. Res. Uli., 13(12), 

1359-1362, 1986. 

Fraser, PJ., and S. Coram, Atmospheric methane, carbon monoxide, and 

carbon dioxide by gas chromatography, 1986, in Baseline 86, edited 

42 

by B.W. Forgan and P.I. Frase r, pp. 65·66, Bureau of Yfetcorology, 

Au stralia, 1988. 

Harris, 1.M., and E.e. Nickerson (Eds.), Geophysical Monitoring for 

Climatic Chang#!. Nf). 12: SummtJ'Y Report 1983, 183 pp., NOAA 

Environmental Research Laboratories, Boulder, CO, 1984. 

Komhyr, W.O., R.O. Grass, and R.K. Leonard, Dobson 

spectrophotometer 83: A st.anda rd for total ozone mea su rements, 

1962- 1981,1. Geophys. Res., 94(07), 9841·9861,1 9890. 

Komhyr, W.O., I.A. Lathrop, R.W. Poston, and T.O. Mullen, ECC 

ozonesonde observations at Sou th Pole, Antarctica, during 1988, 

NOAA Data Rep. ERL ARL·18, 277 pp., NOAA Air Resources 

Laboratory, Silver Spring, MO, 1989b. 

McPeters, R.O., and W.O. Komhyr, Long·term changes in 

SBUVrrOMS relative to the World Standa rd Dobson Ozone 

Spectrophotometer, Proceedings of the 1988 Ozone Symposium, 

University of Goningen, Federal Republic of Germany, A. Deepak, 

Hampton, VA., in press, 1989. 

Quiroz, R.S., Seasonal climate swnmary: The climate of the EI Nmo 

winter of 1982·83-A season of extraordinary climatic anoma lies, 

Mon. Weather Rell., 111, 1685· 1706, 1983. 

Schnell, R.e., and R.M. Rosson (Eds.), Geophysical Monitoring for 

Clima tic Change, No. 15.' SWnJTIilry Report 1986, 155 pp., NOAA 

Environmental Research Laboratories, Boulder, CO, 1987. 
6. Acquisition and Data Management Group 

J. HARRIS (Ed ito,). G. HERBERT. AND J. MCCUTCHEON 

6.1 . CON1Th'UING PROGR~\.IS 

6.1.1. STATION CUMATOLOGY 

Measurements of meteorological variables arc necessary for 

the interpretation of measured values of aerosols. trace gases. 

and turbidity. More than 10 years of melcrological data at the 

four base1ine stations have produced c1imatologics lypical of the 

polar and tropical atmospheres. Surface weather data include 

the measurements of wind direction, wind speed. station 

pressure, air and dewpoint temperature, precipitation amount, 

and a dctennination of boundary layer stability. The current 

sensors used at GMCC stations were selected to withstand the 

extreme conditions of the environment at the two polar stations. 

WMO-recommcnded standards for exposure are used wherever 

possible. Nickerson [1986] gave a complete list of the sensors, 

model numbers, and heights. 

In 1984 the CAMS data acquisition systems were installed at 

all stations; this improved the consistency of the data acquisition 

hardware and reduced the quantity of missing data. The 

meteorological data are printed as hourly average values in a 

Daily Weather Report (DWR), and are checked against 

real-Lime observations by station personnel. The DWRs arc then 

sent to Boulder. where they are edited and microfiched. An 

edited computer file of these data will be stored in the Boulder 

meteorology archive. Herbert el al. (l986a, b) presented a 

detailed discussion on the individual parameters contained in the 

DWR and other CAMS printouts. 

WlNO SPEED (W /S) 

__ ~, ws < 5 

~5 $ ws < 10 

WS ~ 10 

.-.~-. 

f ./ iii 

.,./ ./ ! :' 

! / / 

/ 

/ / / 

( 

WIND rREQ 

, 

Barrow 

Descriptions of the BRW site, its surroundings. and climate 

are given in previous GMCC Summary Reports [c.g .. DeLuisi, 

1981). Wind roses of hourly average resulLant wind direction 

and speed arc presented in 16 direction classes and 4 sp:!ed 

classes (Figure 6.1). The distribution of wind by direction for 

1988 is almost identical to the II-year climatology. A higher 

percentage of calm hours (1.2%) was reported in 1988. The 

predominant wind direction is again from the "clean-air sector," 

northeast-southeast (60%). and all other directions except 

north-northeast are less than 5%. The cast-southeast direction 

logged the year's peak. gust of 25 m S-I on January 2, and this set 

a new January record for the station (fable 6.1). 

The average temperature and pressure for 1988 were 

consistent with the long-term averages, although there were 

anomalous values during the year. The minimum temperature 

for 1988 of -41"C occurred on February 22. and the maximum 

temperature of 17°C occurred on August 5. February was a 

month of extreme variability in pressure and temperature. On 

February 3 a new all-time-high pressure record was set at 1057 

hPa. The minimum pressure for 1988 of 986 hPa was first 

recorded on February 24. In March, the pressure again reached 

the all-Lime high set in February. BRW's climate in August had 

extremes in temperature, missing the 1925 August record low of 

_7°C by I "C based on Ule NWS climate record. In the same 

month BRW logged the year's maximum temperature (17"C). 

Climatologically, August receives the majority of BRW's 

precipitation. as it did in 1988. 

Fig.6.1. Wind rose of surface winds for BRW for 1988 (left) and 1977·1987 (right). The distribulion of the resultant wind direction and speed are in 

units of percent occurrence for the year and 11 ·year period, respectively. Wind speed is displayed as a function of direction in three speed classes. 

43 
TABLE 6.1. BRW 1988 Momhly Climate Summruy 

Jan. Feb. Ma rch April May June July Aug. Sept. Oel. Nov. Dec. t988 

PrevaiJing wind E:-.:E E ENE E ENE E E E;\E !"II£ E ENE ENE El\'E 

direction 

Average wind 6.7 5.4 5.2 5.9 7.2 5.t 5.5 6.t 6.1 5.9 6.7 5.7 6.0 

speed (m s .1) 

Maximum wind 21 16 14 13 14 13 13 17 20 14 18 16 21 

speed· (m 5.1) 

Direction of max. 113 80 27 72 73 118 230 232 204 206 56 99 113 

wind· (deg.) 

Average slation 1014.6 1015.7 1019.4 1016.6 1018.8 1013.4 1011.6 1007.5 1010.3 1017.7 1018.4 1008.6 1014.4 

pressure (hPa) 

Maximum pressure· 1038 1057 1057 1031 1036 1025 1024 1019 1022 1036 1034 1038 1057 

(hr,) 

Minimum pressure· 996 986 989 998 1008 997 988 986 987 tooo 1002 988 986 

(hP,) 

Average air -23.8 -25.5 -24.9 -16.9 -6.5 0.2 3.1 1.5 -2.3 -16.2 -24.9 -22.4 -12.9 

temperature CC) 

Maximum temperature· -I -7 -10 0 4 6 14 15 5 0 -12 - 13 15 

("C) 

Minimum temperature· -40 -41 -38 -36 -21 -9 -2 -6 - 12 -27 -33 -40 -41 

("C) 

Average dcwpoint -4.2 -16.5 -25.3 -23.5 -19.4 

temperature CC) 

Maximum dcwpoint 2 -I -12 - 13 2 

temperature- (oq 

Minimum dewpoinl -12 -27 -33 -41 -41 

temperature- Cc) 

Precipitation (mm) 0 0 0 7 25 34 4 0 0 72 

Instrument heights: wind, 17 m; pressure, 9.5 m (MSL); air and dewpoint temperature, 3 m. Wind and temperature instruments are on a tower 25 m 

northeast of the main building. I hPa = 1mb . 

• Maximum and minimum values are hourly ave rages. 

The measurement of dewpoint temperature began again in 

September with the installation of a new dewpoint hygrometer 

(hygrothennometer, model 1063, Technical Services 

Laboratory, Fort Walton Beach, Florida). 

MaunaLoa 

Descriptions of MLO and its general climatology arc given in 

previous GMCC Summary Reports. The topography of Mauna 

Loa redirccts stronger, predominantly easterly or westerly winds 

aloft down the slope resulLing in a more southerly component. 

A new anemometer was installed at a height of 39 m on 

February 17, 1988. The new configuration now pennits thc 

comparison of winds at different heights. 

The year's minimum temperature (-4·C) and pressure (67 1 

hPa) occurred on December 18 during one of 1988's tropical 

slonns. The next day the year's peak gust (25 m S·I) was 

recorded, accompanied by 51 nun of snow. The maximum 

temperature for 1988 was 19"C on September 21. MLO had a 

dry summer that was relieved by a relatively wet November and 

Decemrer. May was an anomaJous month, having light winds 

from the north II % of the time. High pressure was persistent., 

and only a trace of precipitation was measured. The precipitation totaJ for the year was 410 nun (fable 6.2), which is slightly 

below nonnal. 

44 

The climatology of MLO is often considered as two separate 

regimes, because of the bimodal distribution of the wind 

direction, which depends on the time of day. The day/upslope 

period (0600-1800 LST) and the night/downslope period 

(1800·0600 LST) define the two regimes. The II-year day and 

night wind roses illustrate the two distinct wind patterns (Figure 

6.2). Strong west-southwest and east-soutllcast winds in the 

II-year roses can be attributed to large synoptic-scale Slonns. 

In the 1988 day/night wind roses (Figure 6.3) those anomalous 

winds were not observed. 

Day regime. The II-year day wind rose indicates that light 

wind speeds in the northwest-northeast sector werc observed 

47% of the time. The day regime had calm winds 2.8% of the 

time. The 1988 day wind rose shows an increase, compared 

with the long-term average, in light northerly upslope winds, 

and medium·strength southeast winds. Wind speeds of less than 

10 m S·I from the south-southeast were observed 28% of the 

time, compared wilh the normal of 16%. The characterisLic 

pattern of the winds for 1988 was an increase in the frequency 

of upslope/downslope now. The dewpoint temperature rcOects 

the upslope/downslope events in that upslope now brings moist 

[ropicaJ air from below the trade inversion to the observatory. 

Nighl regime. TIle II -ycar night wind rose shows that 75% 

of all winds observed were from the southwest-southeast sector. 
Prevailin g wind 

direction 

Average wind 

speed (m 5") 

Maximum wind 

speed* (m 5.1) 

Direction of max. 

wind· (dcg.) 

Average station 

pressure (hPa) 

Maximum pressure· 

(hPA) 

Minimum pre ssure· 

(hP.) 

Average air 

temperature ("C) 

Maximum temperaturerC) 

Minimum temperature· 

rC) 

Average dcwpoint 

temperature ("q 

Maximum dewpoint 

temperature· ("C) 

Minimum dewpoint 

temperature- ("C) 

Precipitation (mm) 

Prevailing wind 

direction 

A veragc wind 

speed (m S·I) 

Maximum wind 

speed4- (m S·I) 

Direction cfmax. 

wind- (deg.) 

Average station 

pressure (hPa) 

Maximum pressure-

(hPA) 

Minimum pressure-

(hPA) 

Average air 

temperature (0C) 

Maximum temperature-

(0C) 

Minimum temperatu rerC) 

Average dewpoint 

temperature rq 

Maximum dcwpoint 

temperature· rC) 

Minimum dcwpoinl 

temperature- rC) 

precipitation (mm) 

TABLE 6.2. MLO 1988 Monthly Climate Summary 

Jan. Feb. Ma rch April May June July Aug. Sept. Oct. Nov. Dec. 1988 

Day 

l\l\TW N N1\TW l\1NE N SE N !\tNE NNE N SE SSE N 

~ 3~ 3~ 3.8 ~ 4S 4A 3~ 32 3~ ~ 5A 42 

13 10 10 8 11 12 13 10 9 11 15 15 15 

210 133 174 139 153 137 150 158 172 153 182 172 172 

679A 678.9 680.2 679.8 681.0 68 1.8 68 1.1 680.8 680A 680.2 680A 679.2 680.3 

684 683 684 683 685 684 684 683 683 684 684 683 685 

674 675 676 677 678 679 678 678 678 678 674 671 671 

7.3 6.9 8.0 9.0 l OA 12. 1 10.9 11.5 10.9 9.6 7.6 6.1 9.2 

14 12 14 16 17 18 18 17 18 16 14 12 18 

-2 - 1 o o 2 3 3 5 2 3 ·3 -3 

-8.2 -9.3 - 10.7 -7.2 -5.0 -7.8 - 4.5 -4.3 -3.3 - 1.6 -1.6 -5.9 -5.8 

6 5 467 8 6 9 9 7 7 6 9 

-28 - 33 -37 -26 -25 -27 -32 -29 -32 -26 -24 -40 -40 

53 0 47 35 0 20 0 41 6 40 63 14 320 

Nigh! 

SE SE SSE SSE SSW SSE SSE SSE SSE SSE SSE SSE SSE 

5.2 3.9 4.0 4.1 3.6 5.3 3.9 3.8 3.3 3.8 6.2 6.3 4.5 

16 9 8 9 12 11 15 10 11 13 16 20 20 

215 144 164 161 152 149 151 168 151 150 178 149 149 

679.5 679.0 680.2 679.7 681.1 681.8 680.9 680.8 680.3 680.2 680.5 679A 680.3 

684 683 684 683 685 685 684 683 683 683 683 683 685 

674 675 675 677 678 679 678 678 678 678 675 671 671 

3.6 2.7 3.6 3.8 5A 6.9 5.9 6.8 6.7 5A 4.1 2.6 4.8 

9 9 9 11 12 14 14 13 13 10 7 9 14 

- 1 - 1 -1 - 1 0 2 4 3 0 -4 - 4 

- 12.9 - 14.0 -16.9 - 13.2 -9.9 -11.5 -10.6 -1 1.6 -10.6 --6.8 -4.2 -9.6 - 11.0 

4323566875448 

-23 ·31 ·36 ·26 ·25 ·29 ·29 -30 ·32 ·29 ·20 -25 -36 

20 7 0 0 0 6 2 33 20 90 

Instrument heights: wind, 8.3 m; pressure, 3399 m (MSL); air and dewpoint temperature, 2 m. Wind and temperature instruments are on a tower located 

15 m southwest of tlle main building. 

·Muimum and minimum values are hourly averages. 

45 
MAUNA LOA 

1977-87 

DAY 

\. \ 

\ 

·~~··~~,·-·-t .. ---- ~ 

.. _--+_ ... ······-t--

/ ---1=~ ./ ! 

.. ,---., 

\, . ;>" /. 

1--.=", ...",.' =-2'"''>",, ", .... , -"--. WIND SPEED (W/S) . _'_" -------j---- -- ~"S<5 

czzzz:u £ ws < 10 

liS iI: 10 ~::~~::~~-:- ---_ 

WIND ROSE 

, 

. \ \"'. \ \, 

\. \ \ \ \ 

\ \ \ \ 

·.,f)-l-', -1-E . I . I i 

, / J ! / I 

.I : .: . 

.

i f 

,. / 

, // 

./ ./ 

/' 

WIND I'REQ 

• 

MAUNA LOA 

1977-87 

NIGHT 

w 

WiNo SPEED ( W/S) 

-- 5lO 'II'S<5 

=5 ~ liS < 10 

liS ~ 10 

WI ND ROSE 

s WillI) f REQ 

Fig. 6.2. Wind roses of the surface winds for MLO for 1977·1987 Day (Icrl) and Night (right). The distributions of the resultant wind direction and 

speed are units of percent occurrence for the II-year period. Wind speed is displayed as a function of direction in three speed classes. 

MAUNA LOA 

19fJ8 

DAY 

IV 

WII/D SPEE:O n('~5J 

--5 ~· ... S(5 

r-.S::; WS < IU 

liS .. 10 

-------------------, N WIND ROSE 

s 'fIWI) fREQ 

------- ------

~IAUNA LOA 

1988 

mGHT 

w 

'!fWD SPEED ( W/S) 

= 5::; lI'S < 10 

c::::::J WS i: 10 

N WIND ROSE 

E 

s WI tiD -:fREQ 

Fig. 6.3. Wind roses of the surface winds for MLO for 1988 Day (Iert) and Night (right). The distribution of the resultant wind direction and speed 

are given in units of percent occurrence for the year. Wind speed is displayed as a function of direction in three speed classes. 

At night calm conditions were observed 5.1% of the time. The 

1988 average wind speed of the night regime of 4.5 m s·\ is 

faster than the 4.2 m S-I average day speed (fable 6.2). The 

higher percentage of calm winds at night may be attributed to 

the inclusion of the transition periods at dusk when the flow is 

switching directions. In the night period, dry, mid-tropospheric 

air from above the trade inversion is advected over the station. 

46 

Samba 

A comparison of SMO's 1988 wind rose with that ror lhe 

II-year period shows a very similar disrribution except ror a 3% 

increase in norlh-nonhwest winds, and a 3% increase in 

south-soulheast winds wilh speeds greater than 10 m s·1 (Figure 

6.4). The southeast seelor accounled ror 73% of all wind 

observations in 1988. The average wind speed (Table 6.3) ror 
SA MOA 

1988 

WIND SPEED 0 (/ 5) 

__ ~'WS <5 

c:::::::::::l5 Ii WS < 10 

ws a 10 

.1 

WIND ROSE 

.--~ , 

WI tiD fREQ 

SAMOA 

1977- 87 

, 

, 

WIND SPEED (W/S) 

-- 5'WS<5 

c:=::I5 , 'fI'S < 10 

c=::tws Oi 10 

-- ~-t ._.-- . --$ 

WIND ROSE 

I 

I 

"1110 fREQ 

'" 

Fig. 6.4. Wind roses of the surface wind for SMO for 1988 (left) and 1977· 1987 (right). The distributions of the resultant wind direction and speed 

are in units of percent occurrence (or the year and II-year period, respectively. Wind speed is displayed as a function o f direction in three speed 

classes. 

TABLE 6.3. SMO 1988 Monthly Climate Summary 

Jan . Feb. March April M.y June July Aug. Scpe Oct. Nov. Dec. 1988 

Prevailing wind SSE NNW SE NNW SSE SSE SSE SSE SE SE J>,'NW J>,'NW SSE 

direction 

Average wind 5.2 3.1 5.0 3.6 5.3 6.2 8.4 1.1 1.6 5.9 5.1 4.0 5.1 

speed (m 5. 1) 

Maximum wind 11 12 13 13 13 13 11 11 19 12 15 13 19 

speed. (m 5'\) 

Direction of max. 330 333 292 333 141 159 159 155 89 128 119 321 89 

wind· (deg.) 

Average station 999.1 991.9 1000.2 1000.1 1001.5 1003.3 1003.6 1004.5 1003.1 1001.1 1001.1 1000.0 1001.5 

pressure (hPa) 

Maximum pressure· 1005 1003 1005 1005 1005 1001 1001 1008 1008 1006 1006 1006 1008 

(hPA) 

Minimum pressure· 994 992 994 996 991 1000 1000 1001 1000 998 998 994 992 

(hPA) 

Average air 28.1 28.2 28.2 21.1 21.8 21.0 26. 1 26.3 26.2 26.4 26. 1 26.5 21.0 

tempernture rq 

Maximum temperature· 33 33 32 33 33 32 29 30 29 3 1 3 1 3 1 33 

("C) 

Minimum temperature· 22 24 24 24 24 24 21 23 22 22 22 22 2 1 

('C) 

Precipitation (mm) 160 228 219 119 III 110 110 63 220 196 348 619 2623 

Instrument heights: wind, 14 m; pressure, 30 m (MSL); air temperature, 9 m. Wind and temperature instruments are on Lauagae Ridge, 110m 

nonheasl of the main building. Pressure sensors are in the main building. 1 hPa= 1 mb. 

·Maximum and minimum values are hourly averages. 

41 
lhe year of 5.7 m S·l was 3.2 m s·\ above the long-tenn average. 

July was the windiest month of the year; it had a 9 m S·I 

average. 

In 1987 and the first half of 1988. ENSO was in the low 

index phase. During the laller part of 1988, ENSO switched to 

the high index phase, characterized by below-normal sea surface 

temperalures, slrong easterly surface winds, and enhanced 

precipitation in the equatorial Pacific [lVCP, 1988]. 

Of lhe four GMCC baseline stations, SMO has a climale Ihal 

is the most responsive to ENSO because of its location. There is 

a well-dermed relationship between the phase of the ENS a 

event and the amount of precipitation the island receives 

[\vCP.1988]. In 1988 a dry spring/summer and a wet. 

record-setting falVwinler were the result. December was the 

wettest month on record for the station, having 679 mm of 

recorded rain. The village ofTula was nooded whcn 254 mm of 

rain fell from December 7 to 9. The wind gusted to 28 m S·I on 

the December 8 and 127 mm of precipitalion was measured. 

The 1988 maximum temperature of 34"C occurred on 

February 13, and the minimum temperature of21°C occurred on 

July 10. The year's average temperarure of 27*C was identical 

to SMO's long-term average. The strongest IO-min average 

wind speed of 22 m s·\ occurred on September 15. August had 

lhe year's highest pressure at 1008 hPa, and the highest monthly 

average at 1004.5 hPa. During this period of high pressure only 

63 mm of rain fell, which was the lowest monthly total for the 

year. 

Soulh Pole 

The distribution of the surface wind direction in 1988 ;!l SPO 

is almost identical to that of the II-year pattern (Figure 6.5). 

SOUTH POLE 

1988 

w 

WItlO SPEED (M/ S) 

--5' WS <: 5 

==::15 :;; WS < 10 

WS ;;; 10 

WI ND ROSS 

'0 

WII1 0 f REQ 

The main difference is the shift to higher percentages of 

northerlies and easterlies. The predominant wind directions in 

1988 were grid east-northeast and east (17%) as compared with 

the long-term prevailing north-northeast direction (19%). The 

peak gust for the year of 20 m S·I occurred On October 9, from 

grid north. Wind speeds greater than 10 m sol were observed 

only 3% of the year, consistent with the climatological average. 

The average temperature for the year was 0_7·C wanner than 

the II-year average (fable 6.4)_ March had an anomalously 

warm average of -48.7"C, which was 5"C above the normal and 

set a new station record. March 23 set a monthly all time high 

(-28·C). August, which is usually the coldest month of the 

year, was 2-C above the normal for the month. May moderated 

the warm temperatures with the second coldest May average 

value of -60"C, compared with the 62·C recorded at Ihe station 

in 1986. The year's maximum temperature of -19·C occurrcd 

on December 25 , and the minimum of -78"C occurred on July 

1. OClober logged the year's maximum pressure of 701 hPa and 

set the October record high-pressure average with a value of 688 

hPa. 

6.1.2. DATA MANAGEMJ1'.T 

During 1988 Ihe overall performance of lhe CAMS 

automated data acquisition system was good. From time to 

time, boards, batteries, tape drives, or power supplies were 

replaced, usually with spares available at the station. Such 

hardware failures were expected after 4 years of continuous 

operation. 

Table 6.5 gives the CAMS operations summary for 1988. 

The number of data blocks missing increased from 1987, but at 

SOUTH POLE 

1977 - 87 

IV 

WINO SPEED (W!S) 

-- 5$ " S<5 

c::=:::J5 ~ ws < 10 

ws ~ 10 

'0 

WIND ROSE 

E. · 

WIIIO fREQ 

Fig. 6.5. Wind roses of the surface wind for SPO for 1988 Ocft) and 1977-1987 (right). The distributions of the resu ltant wind direction and speed are 

in units of percent occurrence for the year and Ihe II-year period, respectively. Wind speed is displayed as a function of direclion in three speed 

classes. 

48 
TABLE 6.4. SPO 1988 Monthly Climate Summary 

lan. Feb. March April May June July Aug. Sept. OCI. Koy. Dec. 1988 

Prevailing wind N E,,\E }\"NE ENE E NE E N N E N E ESE 

direction 

Average wind 4.8 4.8 6.2 5.6 5.1 6.5 5.7 6.1 5.9 5.7 4.3 3.9 5.4 

speed (m 5.1) 

.Maximum wind 9 II 12 12 9 13 12 13 14 16 II 8 16 

speed. (m 5'\) 

Direction of max. 351 14 19 354 114 7 26 313 360 4 356 

wind· (deg.) 

Avcrdge station 689.7 680.5 682. 1 679.9 682.0 686.8 671.4 678.2 681.6 687.6 679.4 683.4 681.9 

pressure (hila) 

Maximum pressure· 696 690 693 689 694 700 683 692 698 701 684 697 70 1 

(hPA) 

Minimum pressure· 680 673 672 672 666 669 659 665 664 675 676 675 659 

OlPA) 

Average air -26.0 -42.0 -48.7 -58.5 -60.4 -57.3 -61.8 -57. 1 -56.9 -49.4 -37.4 -26.3 -48.8 

temperature ("C) 

Maximum temperature" -21 -27 -28 -40 -37 -35 -43 -37 -39 -33 -27 - 19 -19 rC) 

Minimum temperature· -33 -53 -63 -68 -73 -75 -78 -77 -71 -65 -48 -32 -78 rC) 

Instrument heights: wind, 12 m; pressure, 2841 m (:\OISL); air temperature, 2 m. The anemometer and thennomclcr arc on a tower 100 m grid 

east-southeast of CAr:. Pressure measurements arc made inside CAr. 1 hPa = 1mb. 

·Maximum and minimum values aTC hourly averages. 

TABLE 6.5. GMCC CAMS Operations Summary. 1988 

Blocks Recorded and (Illocks .MissingJ 

lliock Expected No. of 

Type Description Blocks 1988 BRW ~1LO 5:v10 51'0 

A Hourly aerosol data 2196 2186(10) 2188(8) 2154 (42) 2193 (4) 

B $ccondary aerosol data Variable 1683 1565 9 0 

II Daily aerosol data 366 366(0) 367 )0) 359 )7) 366 )0) 

5 Hourly solar radiation data 8784 8743 (41) 8755 (3D) 86 17 ) 167) 8768 )1 7) 

C liourly CO2 data Variable 7929 (421) 8317 )91) 8209 (2t8) 8187 Jl 2) 

D Daily CO2 data 366 346(17) 365(1) 358 (8) 366 (0) 

E Hourly CO2 calibration data Variable 356 375 355 552 

r- CO2 calibration repon 52 48 53 48 71 

:vi llourly meteorological data 4392 4215 (78) 4349(44) 4382(10) 4369 )29) 

0 Daily ozone data 366 353(13) 365 )2) 366 (0) 364 )3) 

IV Daily meteorological data 366 353(13) 36-l(2) 366(0) 364 (3) 

I Meteorological calibration 366 352(14) 362(4) 365 (I) 364(2) 

N Ozone calibration 52 53 64 56 64 

• Discrepancies between the expected number of blocks and blocks recorded + blocks missing are due to clock problems or autoreslar1s. 

MLO and SPo it amounted to only a few percent at most. At 

BRW and MLO, there was significant loss of data. At BRW a 

fauhy chopper motor on the CO2 analyzer (nol CAMS related) 

was responsible for several days of down time. At SMO thc 

ASR CAMS had hardware problems that were difficult to 

diagnose, and caused this unit to be offline for a few days. 

During a large part of December, although surface ozone data 

were recorded at SMO, the values were not valid because of a 

bad intcrface board. The majority of missing CO2 and MO) 

data at BRW was the result of operator error in which good data 

49 

were overwrilten. Likewise. most of the CO2 data missing for 

SMO was the result of data being overwritten. A memo was 

sent to all stations reemphasizing procedures for tape handling 

that will prevent data from being overwritten. These procedures 

have also been detailed at the annual meeting and during 

Lraining for neW observers. 

Some program changes were made to CAMS. New CO2 

PROMs were installed in SMO and MLO to allow for two air 

line operations. Coding and tcsting of the new ASR PROMs 

was completed in Bouldcr by the end of the year. A 
station-by-station conversion to the new ASR program was 

scheduled for 1989. Changes in the ASR program allow Ihe 

computation of a daily summary of the past 24-hourly average 

values and a daily total for the solar radiation instruments. This 

infonnation will be recorded at 1200 UTC every day in a new 

data block called a 'T" record. The solar radiation values 

displayed on the front panel have been changed from 3-min 

averages to instantaneous values, as requested by the project 

leader. In addition, some of the functions (F2 and F6) were 

improved for ease of operation. A directory read from tape will 

have letter codes to identify the data records. 

6.2. S PECLAL PROJECTS, A ntOSPHERIC TRAJECTORIES 

The GMCC atmospheric trajcctory models have been 

documented in previous Summary Reports. A description of the 

melhodology for the isobaric program was given by Harris 

[1982] and the isentropic program by Harris and Bodhaille 

[1983]. 

Table 6.6 lists trajectories computed during 1988. These 

trajectories were provided for scientists within GMCC, as well 

as for cooperative scientists. Table 6.7 lists various experiments 

supported in 1988. 

The two data sets available for trajectory calculations consist 

of analyzed grids of meteorological data from the NMC. Data 

on the northern hemisphere 65 x 65 grid cover the period 1975 

to the present. Data on the global 2.5' latitude, longitude grids 

extend from 1977 to the present. Data are delivered from 

NCAR on a monlhly basis and are available in house within 2 

months of analysis time_ [n addition, Ihis year a paraUel gridded 

data set for 1980-1987 was obtained fTom the ECMWF. This 

data set was used in several comparison studies and will be used 

as input for a new Lhree·dimensional model lO be completed in 

1989. 

A new feature of the trajectory models is the ability to 

calculate trajectories to arrive at any specified hour, rather than 

just the routine 0000 or 1200 UTe. This feature is helpful for 

computing trajectories for aircraft sampling projects and ship 

cruises. Programs were written to unpack and refonnat the 

European data set so that it could be used as input to the isobaric 

model. 

The ECMWF parallel data set provided the opportunity to 

produce two sets of isobaric trajectories using the same model, 

the only differences being in the analyzed wind fields used as 

input. As background for this comparison, rrellberth and Olson 

[1988] directly compared selected grids from NMC and 

ECMWF. This study found fairly good agreement in the 

extratropics of the northern hemisphere, but considerable 

uncertainty elsewhere. For example, in July 1986 Trenberth and 

Olson report an RMS difference in the U component of more 

than 5 m S-I in a large portion of the southern hemisphere. 

The sensitivity of the isobaric model to these differences was 

investigated by computing trajectories to several sites around the 

globe using both input data sets. Except for sPa, where 

significant differences appeared between pairs of trajectories, 

agreement was better than expected, as in the case of trajectories 

to Katherine, Australia (Figure 6.6). After examining the raw 

input data, it was discovered that both data centers were storing 

50 

TABLE 6.6. GMCC Trajectories Calculated in 1988 

Location or Project 

Greenland 

Korolev cruise track 

Amsterdam Island 

While Sands, NM 

BRW (ensembles) 

Mediterranean 

CURTAIN: Liltle Rock, 

Sl. Louis, Baton Rouge 

Chile 

SMO 

Miami, FL 

Mojave, CA 

Ny Alesund 

Cape Pt. , South Africa 

WATOX: Hampton, VA 

CAPTEX 

Bennuda 

Tijuana, Mex.ico 

TOGA cruises 

ML Lemmon, AZ 

AGASp·I.ll 

SMO (ECMWF) 

MLO (isentropic) 

San Juan, Puerto Rico 

Barbados 

Hemsdy, England 

Gulf of Mex.ico 

TOGA·IV: South Pacific 

Mace Head, Ireland 

TOGA·V 

Lostock Dam, Australia 

CASE flight track 

CASElLeg II 

SI'O 

CURTAIN 

REME, C10udwater and Blue 

Ridge projects 

Alert, Canada 

luna, Spain 

Station M 

Grand Canyon, AZ 

Buffalo, NY 

South Pacific flight 

Little Rock, AR 

Baton Rouge, LA 

St. Louis, MO 

Adrigal, Ireland 

MLO 

Dates 

May 1988 

May-July 1987 

1986·1987 

June 1988 

March-April 1975-1988 

Selected dates 1982-1983 

Oct. 1988 

Selected dates 1984-1988 

Selected dates 1978, 1984, 1987 

June, July 1988, Oct 1988 

Selected dates 1982-1988 

March-April 1984-1988 

1986,1987,Jan.-Oct. 1988 

July 17·21, 1988 

Sept. -Oct. 1983 

1985.1986.1987 

1986.1987 

1986.1987 

Jan.·ApriI1987. Fcb.·AprilI988 

April 1983. 1986 

March, April 1986 

May-June 1987 

March-April 1986, 1987 

March 1986 

1987, 1988 

March 1988 

Sept.-OCI. 1987 

1987 

April-~ay 1988 

Selected Dates 1984,1985,1986 

July 1988 

July-Aug. 1988 

Oct. -Dec. 1986,1987 

April-June 1988 

Aug. 1988 

Selected Dates 1988 

June 1984-June 1985, 

Mar., Oct. 1987 

Nov.-April 1981-1987 

June 1984 

Nov.-Dec. 1979, 1983 

Jan. 1987 

Jan. 1988 

Jan. 1988 

Jan. 1988 

1987 

1987 

wind data at the poles incorrectly. The problem is in the 

ECMWF data for 1980· 1987 and in the NMC data for May 

1986-November 1988. Correction code was written that 

averages valid wind data from 87.5' N and S and stores those 

values at the poles after orienting them with respect to 

longitude. 

Kahl et al. [1989] compared Lhree different trajectory models 

while employing three different input data sets. Trajectories 

were produced for Arctic locations using the GMCC isobaric, 

the GMCC isentropic, and the AES three-dimensiona1 models. 
TABLE 6.7. Experiments Supported During 1988 

Experiment Dates Organization 

WATOX July 1988 GMCC,ARL 

CAPTEX 1983 GMCC 

Mojave 1982·1988 USGS 

CURTAIN April, June, Oct. 1988 GMCC 

RElvlE Aug.-Scp<. 1988 GMCC 

Cloudwalcr Aug . .scp<. 1988 GMCC 

Blue Ridge Aug.·Scp<. 1988 GMCC 

AGASP·I,II M"d>·April 1983, 1988 GMCC 

TOGA·lV, V Jan. 1986,luly-Oct GMCC 

1981, April-May 1988 

GUFMEX Jan.-March 1988 NSSL 

SAGA·II May-July 1987 GMCC,PMEL 

GPCP 1983·1988 ARL, UVA 

CASE July-Aug. 1988 GMCC 

The data sets were the NMC. ECMWF, and Canadian analyzed 

gridded fields. The authors found that sensitivity to the different 

data bases was at times greater than sensitivity to the three 

different methods of dealing with vertical motion. Although this 

type of study cannot lead to conclusions about absolute errors, it 

does give some measure of uncertainty. The median differences 

between 5--day endpoints in this study ranged from 800 to 1000 

km. 

Cluster analysis, a statistical multivariate technique, can be 

used to summarize a large data set or to explore structure within 

a data set. This spring a UnivCTsity of Virginia scientist gave a 

seminar about cluster analysis applied to ttajectory data; after 

the seminar, members of our group developed procedures on the 

computer to employ this technique. The object of the clustering 

algorithm is to group trajectories of similar wind speed and 

direction so that those within each cluster represent a similar 

flow pattern. Cluster membership is detennined by minimizing 

the within-cluster sum of squares of trajectory locations from 

the mean trajectory for the cluster. Each cluster may then be 

represented by its mean trajectory or cluster mean. Although 

exploration of different clustering procedures continues, some 

preliminary results are shown here, using a hybrid technique 

suggested in the seminar, which has worked well with 

trajectories. The technique uses Ward's hierarchical method to 

determine the number of clusters and an initial grouping. These 

clusters are then refined, using an iterative optimization 

algorithm (SPSS-X Quick Clusler). 

For the first example, MLO 700-hPa, 5-day back trajectories 

for December 1987 through April 1988 were clustered. Figure 

6.7 shows mean trajectories for the three clusters determined. 

The analysis discriminated two wind speed groups from the 

west. accounting for 35% for lrajectories (clusters 2 and 3). The 

one easterly cluster accounts for the remainder of trajectories. 

To contrast with the warm season, trajectories for lune-October 

1988 were then clustered (Figure 6.8). The cluster means show 

on1y easterly flow, although 19% of the trajectories are 

represented by a mean trajectory with some anticyclonic 

curvature from the north. 

Plots of cluster membership, which show all trajectories in 

each cluster on one page. were created to verify that the cluster 

51 

l 

111/1' £ 

10 ' If r-'TT- ---,r-P)'------------ _ _ 

U(ff o~~;" , .dJ , 

'C::::!:::::::.r::::>~ t7.- . -- _ 

..aJ\ 

tJ ~'?> 100' t 120' C 140' C 1&0' C IIW'C 

Fig. 6.6. Back trajectories for Katherine, Australia, September 25, 

1987, created using l\TMC (lOp) and ECMWF (bottom) analyzed grids. 

Numbers along each trajectory give the days back from Katherine. 

Lette~ identify the level and time--A: 850 mb, 0000 UTe; B: 700 mb, 

0000 UTC; C 850 mb, 1200 UTC; D, 700 mb, 1200 UTC. 

mean is representative of trajectories in the cluster and to 

determine the variability within a cluster. Figure 6.9 is the 

duster membership plot for cluster I, Figure 6.8. Although not 

always readable, labels on each trajectory tell the month during 

which they occur. Note that this cluster contains 101 

trajectories of roughly the same length and direction. None of 

these 5-day back trajectories travels over the North American 

continent. 

Figure 6.10 shows four cluster means determined for SMO 

]987 850-hPa trajectories. These indicate 79% of trajcclOries 

(clusters 1 and 4) are from the southeast Pacific tropical region, 

11 % from the region of the Australia-New Zealand anticyclone, 

and 10% from the northwest with possible northern hemisphere 

influence. These are the three source regions identified by 

lIalter et al. [1988J in lheir 'lUdy of CO, variabililY al SMa. 

The cluster membership plot for cluster 2 (Figure 6.11) shows 

more variability than the MLO example. There are many 

instances of cross-equatorial flow, the strongest of which arc in 

January and February. 
JO· N 

10" N 

10· S 

700 MB TRAJ ECTORII::S TO MLO (19 :>3N . 15558W) 

WIN - SPR 198B 5 DAYS 

299 CWSTERE:D. 5 MISSING 

~'YJI;J 9" 

26~ 

-,-/0 2--.. 

) }~ 

& <JS''- ~, 

100· E 1200 E 140' E 160' E lao· W 160· W 

6:>"-

, 

140· W 120· W 100· W 

Fig. 6.7. Mean trajectories for clusters fanned from December 1987 to April 1988 700-hPa MLO 5-day back trajectories, showing percent of 

total trajectories in each cluster. The numbers are cluster numbers for identification only. 

700 MB TRAJECTORIES TO N LO (19.53N. 155.saW) 

SUM- fAL 1988 5 DAYS 

306 CWSTERED. 0 MISSING 

70·N,---------------------~~~~~----_r-------c~~~~~--~" 

~ 

50· N 

;J 19 ~ 

30' N 

0 d--i~ 10" N 

~, 

10· S 

100' E 120· E 140· E 160· E IBO' W 160' W 140· If 120' ", 1000 W 

Fig. 6.8. Mean trajectories for clusters fanned from June 10 October 1988 700-hPa MLO 5·day back trajectories, as in Figure 6.7. 

52 
50' N 

700 MB TRAJECTORIES TO ~!LO (J9.!)JN. 155 58\111 

SU t.l-fAL Ba 5 DAYS 

CLUSTER I N- 101 

Fig. 6.9. Ouster membership for cluster 1, Figure 6.8. Numbers at the end of each trajectory lell me month of occurrence. 

) 

<' 

V 

650 MB TRAJECTORI£.S TO SMO (L 4 25S 170 56W) 

ALL Of t967 5 OAYS 

691 CWSTEREO. 2 1 MISSING 

377, 

'" 

150' E 170' E 130' W 

Fig. 6.10. Mean trajectories for clusters fooned from 1987 850-hPa SMO 5-day back trajectories, as in Figure 6.7. 

53 
8!,)() Mn TRAJECTORIES TO SMO (1 4 255. 170 56W) 

ALL o r 1967 5 DAYS BACK 

(" LUSTE:R 2 N- 66 

---------

1ft tl 

11 0~ F: I:JO' f. If,O' F" 1700 f. 170' w 150' W ]30' II' 

Fig. 6.11. Ousler membership for cluster 2, Figure 6. 10. Numbers at the end of each trajectory teU the month of occurrence. 

6.3. REFERENCES 

DeLuisi, 1.1. (Ed.), Geophysical Monitoring for Climatic CluJnge, No.9: 

Surnmtlry Report 1980, 163 pp., NOAA Environmental Research 

Laboratories, Boulder, CO, 1981. 

Hams, J.M., The GMCC aunospheric trajectory program, NOAA Tech. 

Memo. ERL ARL-116, 30 pp., NOAA Environmental Research 

Laboratories, Boulder, CO, 1982. 

lIarris, J.M., and B.A. Bodhaine (Eds.), Geophysical Monitoring for 

Clima tic Change, No. 1 1: SWIWIIlry Report 1982, pp. 67·75, NOAA 

Environmental Research Laboratories, Boulder, CO, 1983. 

Herbert, G.A., E.R. Grecn, J.M. Hams, G.L Koenig, and K.W. Thaut, 

Control and monitoring instrumentation for the continuous 

measurement of aunospheric CO2 and meteorological variables, 1. 

Atmas. Ocean. Technol. 3, 414-421. 19800. 

Heme", G.A., E.R. Green, G.L. Koenig, and K.W. Thaut, Monitoring 

54 

instrumentation for the con tinous measurement and quality 

assurance of meteorological observations, NOAA Tech. Memo. ERL 

ARL-148, 44 pp., NOAA Environmental Research Laboratories, 

Boulder, CO, 1986b. 

Kahl, J.D., 1.M. Hams, G.A. Herben, and M.P. Olson, lntercomparison 

of three long-range trajectory models applied to Arctic haze, Teilus, 

418. 524·536.1989. 

Nickerson, E.C. (Ed.), Geophysical Monitoring for Climatic Change, 

No. 13: Summary Report 1984, III pp., NOAA Environmental 

Research Laboratories, Boulder, CO, 1986. 

Trenberth , K.E. and 1.G. Olson, Intercomparison of NMC and EC~1WF 

globaJ analyses: 1980- 1986, NCAR Tech . Note, NCAR/TN 301 +STR, 

8 1 pp., National Center for Atmospheric Research, Boulder, CO, 

1988. 

WCP (World Climate Programme), Climate System Monitoring MOnJhJy 

Bulletin, 1988, Vol. 10, 42 pp., World Meteorological Organization, 

Geneva, Switze rland, 1988. 
7. Air Quality Group 

Y. KIM (Ed;to,). J.F. BOATMAN. H. SIEVERJ]';G. J. RAY. C. V A':' VALIN. AND L. GUNTER 

7 .1. CONTINUING PROGRAMS 

7 .1.1 . Th~ODUcnON 

AQG research during 1988 had four objectives: (l) to 

improve understanding of the acidic deposition phenomenon; 

(2) to determine the amount and fate of various trace species 

IhaL are advected eastward from NOM America; (3) to provide 

an observational data base to validate the acid deposition 

models; and (4) to gain a bener understanding of the 

conccnlralion of acid-causing agents within clouds. AQG 

acquired data to satisfy these objectives using the NOAA King 

Air research aircraft (Figure 7.1). Table 7.1 summari zes the 

research flights made by the King Air in support of our activities 

during 1988. 

7.1.2. GLOBAL CHANGE EXPEOmON Al\TI COORDINATED 

AIR-SEA EXPERI~fEl\" 

CASE was conducted during the 1988 GCE. The NOAA 

King Air was deployed over the western North Atlantic Ocean 

to sample certain pollutant gases (on a real-time basis) and 

Scientist 

k" lrumcnl ,-='1 nl=~-, Rac~$ 

Co-Pilot 

Sola' A.1d a~on ";,-Sample tnte! 

/ 

--

Insuument A.1dt 

Fig. 7.1. The KOAA King Air C-90. configured for research. 

55 

aerosol particulate matter (by filter packs) in a coordinated 

effort with the NOAA ship Mt. Mjlchell during leg I of GeE. 

CASE sampling and analysis has provided intercomparison data 

on °1, 502' and NOy gas concentratioru; on fine- and coarsefraction particulate matter; on sulfate. nitrate. chloride, sodium. 

and other ion concentrations; and on a number of elemental 

concenlrations in the total particulate malleT. Meteorological 

data obtained from the King Air arc being compared with 

sounding data obtained from shipboard radiosonde releases 

[Boatman el 01.. 1989a}. CASE aircraft nights took place on 

July 17, 18. 19 and 21. 1988. off the coast of Cape Ha!leras. and 

July 26, 27, and 28, 1988. upwind of Bermuda. TIle night 

pattern provided sufficient time for free troposphere (2600 m) 

and lower marine boundary layer (ISO m) filter pack sampling 

and onc additional altitude (600 to 900 m) for S-IO min time 

averaging of the real-time gas analysis data. 

An additional feature o f the CASE program was the careful 

sampling and analysis of particle si7.e distribution using the 

Knollenbcrg optical sizing probes and previous experimental 

empirical formulas for aerosol water. This work has enabled 

AQG to determine aerosol water volume and mass fractions. 

This work also identifies the contributions of the (1) 

predominantly anthropogenic accumulation mode. (2) soil 

intermediate mode, and (3) sea salt coarse mode volume and 

mass to the total observed volume (Kim el al., 1989J. nlis latter 

aspect will prove invaluable because the fine- and coarsefraction particulate maHer detenninations from aircraft and 

shipboard sampling arc compared. 

Excess sulfate (XS04 • after sublracting sea sal t sulfate) was 

found to be remarkably high in the Bcnnuda area, -1 .... g nrl. 

The aircraft ISO-m-Ievel Bermuda-area average XS04 of 1.01 

Jlg m') was very close to the tllree shipboard RemlUda -area 

average XS04 values of 1.06 jlg m·

l, 1.09 jlg m·3• and 1.03 jlg 

m·l, using three distinct filter pack systems. 

The coarse· fraction XS04 was observed to be greater aboard 

the aircraft (-30%) than aboard ship (-20%). This discrepancy 

is considered to be due to a smaller particle size cut for the 

cyclone separator aboard the aircraft than for the cascade 

impactor aboard the ship: 0.6-0.9 jlJTl diameter versus 1-1.5 JlIll 

diameter (Sievering et al., 1989}. 

A large chloride deficit (i.e., relative to the sea water erINa' 

ratio of 1.16S) was found to be very sLron gly correlated with lhe 

sum of nitrate and excess sulfate. This suggests that the 

heterogeneous conversion of 502 to sulfate in and on sea salt 

aerosol is an important contributor to the total excess sulfate 

observcd in the remote North Atlantic marine boundary layer 

ISjeverjng el 01 .. 1989). 

7.1.3. CE\TRAL. U.S. RADM TEST AND ASSESS>IThT 

I;-" ~"sIVES 

TIll! 2-year CURTAIN program was completed in 1988. 

Seasonal observations of trace gases, aerosols, and 

meteorological parameters were obtained in the south-central 
TABLE 7.1. NOAA King Air Research Flights During 1988 

Dale 1988 Stan End 

CURTAIN ProjeC/, Uure Rod. AR 

(CST) (CST) 

Jan. 22 1337 1745 

Jan. 23 (I) 1135 1547 

Jan. 23 (2) 2021 2441 

Jan. 25 1150 1550 

Jan. 26 (I) 1128 1530 

Jan. 26 (2) 2300 0313 

(COT) (COT) 

Apr. 21 1208 1625 

Ap<.22 (I) 1025 1442 

ApL .22 (2) 2214 0233 

Apr. 24 1016 1430 

Apr. 25 2217 0231 

Apr. 26 1110 1523 

June 19 (1) 003 1 0442 

Junc19 (2) 11 17 1528 

lune 20 09 12 1322 

lune 21 0905 1322 

iune 22 (I) 0922 1332 

iune 22 (2) 2212 2624 

(CST) (CST) 

Oct. 18 1136 1602 

Oct. 19 (I) 1120 1541 

Oct. 19 (2) 2153 02 12 

Ocl. 21 1145 1613 

A' .. 22 (I) 1028 1441 

A, .. 22 (2) 2205 0222 

Blue Ridge Flighls,l-Iarrisburg. PA 

(EDT) (EDT) 

Aug 16 (I) 1027 1355 

Aug 16 (2) 1505 1822 

Cloud Wafer Flights, Harrisburg . PA 

(UTC) (UTC) 

Aug 18 1231 1442 

Aug 19 1433 1757 

Aug 20 1436 1710 

Aug 29 1347 1647 

Sept. 4 1435 1826 

United States. Research aircraft flights using the NOAA King 

Air were made from a base site in Little Rock, Arkansas, north 

and south along the 91-30-W meridian. A climatological data 

base was established by making seasonal field observations in 

February, April, July, and October, during 1987, and in January, 

April, June, and October, during 1988. The purpose of the 

studies was to make observations for comparison with RADM, a 

model that covers the eastern half of the United Slates. In the 

future, the observational data base will be an aid in the model 

initialization along the RADM western boundary. 

Each field intensive mission included six flights, consisting 

of a repeating series of two day flights and a night flight. Day 

flights alternated between northward to Missouri and southward 

to the Gulf of Mexico. Night flights had shorter flight legs but 

included both north and south segments from the Little Rock 

56 

Dale 1988 SIan. End 

ACID·MODES Study,l-Iarrisburg. PA 

(UTC) (UTC) 

Aug. 21 (1) 1430 1845 

Aug. 21 (2) 1949 2206 

Aug. 22 (I) 1426 1830 

Aug. 22 (2) 2015 2330 

Aug. 26 1657 2039 

Sep'. I (I) 1347 1800 

Sep'. I (2) 1943 22 19 

Yelloslone Smoke Flight, Boulder, CO 

(MDT) (MDT) 

Sep'.7 2200 2344 

GCEtCASE, Newport News, Va, and Bermuda 

(UTC) (UTC) 

July 17 1251 1733 

July 18 1250 1718 

July 19 1405 1818 

July 21 1235 1653 

July 26 1151 1609 

iuly 27 (1) 1054 1502 

iuly 27 (2) 1700 21 17 

iuly 28 1125 1524 

BAD Tower Flyby, Erie. CO 

(MDT) (:-1DT) 

Ocl. 13 1355 1519 

CFC Ins/rumen! TestjljghJ,N.E. CO 

(MST) (~1ST) 

Dec. 6 0800 1200 

Ozone Instrument Test Flight, Boulder, CO 

(MST) (MST) 

Dec. 16 10225 1300 

Nephelometer Test Flighl. Boulder. CO 

(MST) (MST) 

Dec. 16 1524 1709 

base. During each flight, two altitudes 1450 and 2450 m above 

sea level, were flown. A stepwise profile was added to the 

flight plans in 1988. All flights attempted to sample only in 

clear air. 

Hydrogen Peroxide Measuremenls 

Instruments to measure ambient HzOz on a continuous basis 

have become available only recently [Lazrus el al., 19861. HzOz 

is an important photochemically produced oxidant that is a 

by-product of the OH radical oxidation of nonmethane 

hydrocarlxms. It is fonned by a termination reaction of HOz 

radicals, and as such is an indicator of recent concentrations of 

free radicals in the atmosphere. HzOz is thought [0 be important 

in the oxidation of SOz to Hz

S0 4 in aqueous-phase reactions. 

Several researchers have reported aircraft-based measurements 
of HZ

02 [Van Vali,t et a/., 1987; Heikes et af., 1987; Barth el al., 

1989; and Boalman el al., 1989bJ. 

Measurements of H20 2 made during CURTAIN show a 

strong annual cycle. Mean and standard deviations for seasonal 

field programs are shown in Figure 7.2a. Winter mean H20 2 

values arc ncar 0.2 ppbv whereas summer mean values are near 

4.0 ppbv. The winter to summer increase of a factor of 20 is 

most likely due to increased solar radiation and to greater water 

mixing ratios in summer. There is a linear relationship between 

water mixing ratio (WMR) and H2

0 2 concentrations (H20 2 = 

0.327. WMR - 0.380, R2 = 0.89) when mean values for eaeh 

field program arc compared. Individual flights, however, show 

poor statistical correlations. This most likely reflects the 

difference in time coefficients for the production and loss of 

H20 2 compared with humidity. In addition. the detailed 

structure in the measurements during flights is indicative of 

meteorological influences and changing precursor 

concentrations. 

Allirude profiles were made in 1988 field programs in 

addition to the two lcvel-flight-altitude segments. Heikes el af. 

l1987] reported that H20 2 generally increased with altitude in 

measurements made in the eastern United States during the fall 

of 1984. AQG observations during 1987 at two altitudes 

indicated a general decrease in H20 2 with altitude; for 1988, the 

H20 2 profiles were highly variable, each flight being different 

(Figure 7.3). In winter there was very little variation in H20 2 

with altitude. Spring and summer had generally decreasing 

H2

0 2 with altitude. and fall had increasing H20 2 with altitude up 

to about 2000 m. Computer models (Kleinman, 1986] have 

suggested that 112°2 should increase with altitude in the 

6 -- ---- -- - --- - - -----

5 (a) 

> D 

Q 4 • Q , \ • N 3 /, 

N 

0 

J: 

2 

• 

• 

v \ a=-- ! 

~ • 

0 

(b) 

80 > • D 

Q 70 Q 

ru 

c 60 0 

N 

0 50 

40 

(e) 

4 

> D 

Q 3 Q 

N 2 0 

U) 

0 

0 

. -------- . ~. '-'/ --- -------- ~==-.-- . . . -.:: 4 8 12 4 8 12 

1987 Month of Year 1988 

Fig. 7.2. CURTAIN dala for 1987·1988. Squares are upper altitude 

values, and triangles are lower altitude values. Dashes and dots are !.he 

± standard deviations. H20 2 and 0 3 had annual cycles, but 502 did not. 

57 

boundary layer. Logan et al. [198 1] modeled H,02 (0 higher 

altitudes and concluded that H20 2 should decrease with altitude. 

Only more measurements and updated models will clarify this 

situation. 

Computer models also predict a daily cycle for H2

0 2. having 

maximum concentrations in late afternoon. In CURTAIN a 

day-night difference in H2

0 2 was observed, but with the higher 

values at night. The night/day ratio varied from 1.15 to 2.7 and 

did not appear to follow a seasonal cycle. The data validate the 

prediction of a daily cyc1e but not the times for the minimum 

and maximum. The night maximum may be explained partly by 

the timing of the measurements. Daytime nights were centered 

around noon, and night flights were centered about midnight. 

Hence, day flights were during the buildup period well before 

the predicted maximum. The night flights occurred before 

significant losses and well before the early morning predicted 

minimum. Thus, daily maximum H20 2 concentrations are 

predicted to be greater than the measured nighttime values and 

the reported means are not the "true" mean that would be 

obtained by more frequent measurement of the daily cyc1e. 

Other Trace Gases 

0 3 was also measured during the CURT AJN program. 

Figure 7.2b shows 2 years of seasonal data. The annual cycle 

for 0 3 was clearly observed, although the seasonal maximums 

were different for the 2 years. The difference in 0 3 concentrations at the two altitudes was not consistent. Mean winter 

values for 1988 were 52 ppbv. and mean summer values were 

80 ppbv. The standard deviation for the summer was relatively 

large, which was a reflcction of the large differences seen 

between different flights. 

As indicated in Figure 7.2c, S02 did not appear to have an 

annual cycle in the south-central United States. Also. compared 

with the northeast United States. the S02 values are low. Figure 

7.4 shows the ratios of H20:/S02 for 1987-1988. A ratio above 

1 indicates oxidant in excess of that needed for complete 

conversion of 502 to H2S04 in cloud water. The boundaries of 

the hatched surfaces indicate the upper and lower altitudes 

measured in the CURTAIN flights. The 2 years are very 

,-------~----------~~ February '988 June'988 

, , , f\ ' ,.\ ..... } ..... .. ;', .... \ 

\ ............. \ ." . .... . 

I ".' 

,. 1 t 

. ,'\ t. , .. ~~-r-r,-,-~-r~---r---r--,---,---,---r-~ 

a a2 a.' a.1 a.' 

H,o,_J ",o. 1J>IlCw1 

Fig. 7.3. ProfLIes for H20 2 for February and June, 1988. The summer 

flights show greater flight-to·flight variations. Largest values are for the 

night (N) flights in both seasons. 
5 

4 ~ 

0 3 ~ 

"' >. 

'? 

~ 2 

5 7 

Month of Year 

9 

....... .... ... 1: 1 

11 

Fig. 7.4. The ratio of 1-1 202"'S02 for both altitudes at which data were 

collected, for 1987 and 1988. Ex.cess oxidant was available for most of 

each year. 

different. which is primarily due to the irregular conccnlrations 

of 502' Winter generally has a limited amount of oxidant. and 

the rest of the year has an excess of oxidant. Thus, acid 

fonnalion would be expected 10 occur rapidly in the spring and 

summer in this region but to be limited by the lower available 

SO,. 

Aerosols 

Figure 7.5 shows the scasona1 variation of average smallparticle (0. 1-3 ~ diameter) aerosol numhcr concentration 

oblained using the ASASP at low and high alLitudes [Kim et al., 

1988]. It shows that small-particle concentrations at bolh 

altitudes and during day or night arc maximized in spring and 

summer and minimized during fall and winter. This supports 

the results of Mueller el 01. [1980]. High.altitude concentrations 

during both day and night are smaller than those at low ahitudc. 

At least four processes affect the seasonal aerosol cyclc. Firsl, 

anthropogenic aerosol production may be higher during the 

heating and cooling seasons (winter and summer). Second, 

during the snowy months whcn substantial areas of frozen 

ground exist, soil·derived particles arc minimized [Gillelle and 

lIansen, 1988]. Third. photochemical and wet conversion of 

S02 to SO;· is faster during summer [Meagher et af .• 1983]. 

Fourth. natural emissions of isoprene and hydrocaroons increase 

in spring and summer. 

7.1.4. RADM EVALUATION EXPERIMENT 

Two aircraft. the NOAA King Air and a Battelle Pacific 

Northwest Laboratories DC-3. made three coordinated research 

nights on June 24 and June 30. 1987 (Figure 7.6). Each night 

was along a track from Columbus. Ohio, to Pittsburgh, 

Pennsylvania, to Pennsylvania State College. Pennsylvania 

(36"N), to Binghamton, New York. to Utica, New York. to 

Saranac Lake, New York. The DC·3 flew in !.he planetary 

boWldary layer at an altitude of 1.1 km (3500 ft) aoove sea 

level. The King Air new in or above the planetary boundary 

58 

1200 

c 

0 " 00 ~ 

C 

Q) 800 u 

c 

0 

0" 600 ~ E 

~~ 

E 

:J '00 

z 

(5 

"' '00 e 

Q) 

« 0 

J 

w: 

/ 

1/ . 

/7 

cf 

F M A M 

-~ '-

J J 

Month 

A 

day. low 

~ day. high 

.) night. low 

night. high 

SON D 

Fig. 7.5. The mean aerosol number concentralion at high and low 

altiludes during eaeh of the CURTAIN field periods. 

layer at altitudes between 2.4 and 3.4 km (8000-11000 ft) above 

sea level. The two aircraft began and ended the flights together, 

each flying along its same flight tracks on each night. The 

relationships betwccn selected acid precursors were evaluated 

along the night tracks, in concert with the known meteorological 

conditions. 

The primary purpose of this study was to gain a beller 

understanding of the concentrations of acid precursors present 

above the northeastern United Statcs during summer. Two 

secondary purposes were to use this new understanding in 

evaluating the RADM [Chang et 01., 1987J and in designing 

additional field studies for the EPA's ACID-MODES program. 

Figures 7.70-d show the patterns of selected trace gases 

observed with the aircraft. 

A large patch of 502 having concentrations as high as 10 

ppbv was ev ident in the planetary boundary layer above 

Pittsburgh. A second weaker patch (2 ppbv) was present in the 

free troposphere above Columbus. The fact that this patch was 

observed both in the morning and afternoon suggests its origin 

to be stable surface emissions. 

In the planetary boundary layer, the H20z concentration field 

(Figure 7.7b) was similar in the two flights. However, in the 

free troposphere, !.he concentration pallern oolh expanded and 

intensified during the second flight. Peak concentrations in the 

free troposphere rose from 2.5 ppbv to 3.0 ppbv. These changes 

definitely suggest the secondary production of HzOz during !.he 

day. 

It is interesting that the region of expansion and 

intensification was mostly in the free troposphere. Luria et al. 

(1989J showed that HzOz is formed in the presence of ultraviolet 

light through chemical reactions involving Nay. 0), and the OH 

radical. These reactions arc accelerated in the presence o f water 

vapor. Ultraviolet light is more abundant at higher altitudes. 

Conversely, the water vapor concentration decreases with 

altitude. The speculation is that the region of maximum HzOz 

production was achieved at an altitude balanced between these 

two competing factors. The peak in !.he HzOz pallern above 
Fig. 7.6. Flight tracks flown during the RADM Evaluation Experiment. 

Sce text for locations. 

600 

a 5°2 :::- Yh~i/'~) L ¥2 

7DO !~ rDO ! 11m

, II 0\, 

""'; 1\ "" "'(;;' 'f 0 E 0 /) 30 ; ~\~.s 

j 8DD , ' '\ _ 8DO~r/ ~/ (~g;, 

£ ::: ~Ji11<- 1/IIjIJ ::: ~-/- II: II' . ( !;%!. \~ !1I1\ '11/ I .'~ n I:::) 950 j ______ '" ",,--,-"" /;I 1 'IIi ,1. l "1 950 " " _____ . " "'-'''' Ij Ii' 

., . ' '~, ~ ~ ~ . ~ 1000 1-- ,_ ..• --,_ .. -.,-,-'--'- . ~ 1000 1-,-·-,.......,·--r--,--,-,--.-· , 

o 200 400 600 600 1000 0 200 <l00 600 800 1000 

Fig. 7.7. Concentration prof Lies of selected trace gases observed with 

the NOAA King Air aircrafl on June 30. 1987: (a) S02 concentrations 

contoured at 1 pphv intervals, (b) H2

0 2 concentrations contoured at 0.5 

ppbv intervals. (c) OJ concenuations contoured at 10 pphv inLervals, and 

(d) NOy concentrations contoured at 1 ppbv inLervais. Dolled lines 

represent the night aJtitude (ambient pressure). 

59 

Colwnbus is associated with enhanced OJ' NOy' and probably 

hydrocarbons. 

The JX!ak 03 concentration observed in the afternoon night 

(Figure 7.7c, lID ppbv) was 30 ppbv higher Ihan Ihal of Ihe 

morning flight (80 ppbv). The enhancement also expanded in 

size 1O cover much of the lower troposphere between Columbus 

and Pittsburgh. The obvious explanation for these observations 

is strong photochemical production in a polluted region on a 

clear summer day. This rate of OJ increase (4 ppbv h'\) may be 

near the maximum attainable for this region. 

NOy concentrations (Figure 7.7d) were generally less than 2 

ppbv, except in a patch in the planetary boundary layer above 

Pittsburgh. The JX!ak NOy concentration increased from 5 ppbv 

to >8 ppbv in this patch between the two nights. This could 

have been due to NOy production or to sampling in a different 

part of the plume above Pittsburgh on the two flights. The 

fonner suggestion is more plausible, but the latter cannot be 

ru1ed out. 

The following conclusions wcre drawn from this work: 

(1) The concentrations of both S02 and HzOz were higher 

during the flights of June 3D, 1987, than during the night of 

June 24. 1987. A cold front had passed through the area 

within 24 hours of lhe June 24 flight. The June 30 flight was 

through a stagnant warm-air mass of subtropical origin. 

(2) SOz concentrations averaged 1-2 ppbv within the 

planetary boundary layer and <1 ppbv in lhe free troposphere. 

Superimposed on these background concentrations were 

surface source regions having elevated concentrations as high 

as 14ppbv. 

(3) HzOz concentrations averaged 2-4 ppbv. The highest 

\'alues were observed near the top of the planetary boundary 

layer. 

(4) The ratio between H20 2 and SOz was greater than 1. 

except in the lower planteary boundary layer and in the 

vicinity of surface 502 source regions. The ratio was much 

less than 1 in the lauer regions. Further studies are necessary 

to confirm whether this is a typical summer condition in those 

regions. 

(5) Two daytime nights were made on June 3D, 1987. 

The patterns of both SOz and H20z rcmained substantially the 

same. An increase in the concentrations of SOz and H20 2 was 

observed in the second night. 

7,1.5. ACID-MODES EXPERlMENT 

During Augrnt and early September, 1988. AQG participated 

in the EPA-sponsored ACID-MODES experiment, centered in 

Pennsylvania. One purpose for our participation was to measure 

the acidity and the acid-causing agents within clouds using the 

NOAA King Air aircraft. Our working hypothesis was the 

following: 

Both H2

0 2 and 502 are readily absorbed by cloud water. 

where they quickly react to fonn sulfuric acid. Therefore. in a 
polluted cloud, the concentrations of HzOz (oxidant) and S02 

(oxidizer) in the air between cloud drops arc mutually exclusive. 

AQG collected cloud water samples and made interstitial air 

measurements on five occasions. Each sampling flight lasted 

long enough to collect 10 cloud water samples and to measure 

the H20 2 and SOz concentrations simultaneously within the 

clouds. All flights were made during daylight hours in 

extensive stratiform cloud layers. 

On August 19, 1988, the King Air flew within a nonprecipitating stratus cloud above central Pennsylvania for aoout 

1.5 hours. During this time 10 cloud water samples were 

collected while cloud liquid water content, SOz concenlration, 

H20 2 concenlration. and 0) concenlration were being measured. 

Figure 7.8 shows the isobaric back trajectories for 1200 UTC 

on August 19, 1988, with termination at Harrisburg, Pennsylvania. The 1000 mb (L) and 850 mb (M) trajectories suggest 

that the air at these levels arrived from the north or northwest. 

The 700 mb (U) trajectory suggests that air at this altitude 

arrived from the west-northwest. 

Figure 7.9 swnmarizes the salient features of the dala from 

the August 19 flight. The flight altitude, liquid water content, 

S02 concentration, H20 2 concentration, and 0) concentration 

are plotted versus time. Also shown is the pH of each cloud 

water sample collected. 

The aircraft remained within the clouds for about 1.5 hours. 

The cloud layer was thin, extending between 900 and 850 mb 

(depth = 600 m). The I-min average liquid water content 

hovered ncar 0.2 g m'), a low but reasonable value for a summer 

Slratifonn cloud. The S02 concentration was between 2 and 4 

ppbv, a value typical of polluted summer conditions (Boatman 

et al., 1989b]. The Hz0 2 concentration was less than 0.2 ppbv 

with the cloud. This is an order of magnitude lower than that 

typical of polluted swnmer conditions [Boatman et aL, 1989b), 

The 0) concentration was between 45 and 68 ppbv. The pH 

80' W 

Fig. 7.8. Isobaric back trajectories (L: 1000 mh, M: 850 mh, V: 700 mb) 

ror 1200 UTe on August 19, 1988, with termination at Harrisburg, 

Pennsylvania. Numbers are positioned al I-day intervals along the 

lrajectories. 

'oo~----------------------------------, 

800 -; 

-;;-

E 

!!) 0.5-] () 

;: 

~ 

0 

5 

,- , - ~ 

"- 3 -, 

0 '" 2 -

<J> 1 • 

0 

1 

0. 5 .... 

0 

70 

,-

~ 60- "-

0 '" 50-

40 

15:30 

. ,. J 

16:00 

Cloud Top 

Cloua Base 

V\ r, . , /1' ...... //-

16:30 17:00 

Time (GMT) 

---

\ 

, ., 

.1\//\ i \ 

" I 

17:30 18:00 

Fig. 7.9. Temporal variation or night ahitude (ambient pressure) and pH 

or cloud water samples, liquid water content, S02 concentration, 1-1

2°2 

concentration, and 0) concentration within the clouds during the night 

or August 19, 1988. 

measurements from the to cloud water samples varied between 

2.3 and 3.1. Such values arc very acidic, suggesting active acid 

formation within the cloud drops. 

The following conclusions were reached on the basis of the 

results from this and the other four flights: 

(1) The concentrations of interstitial HZ02 and S02 were 

mutually exclusive, except in one unpolluted case. 

(2) In the polluted cases, H2S04 was fanning in the clouds. 

These clouds had pH values as low as 2.3: 

60 

(3) Trajectory analysis showed that the polluted air 

observed in clouds over Pennsylvania had lingered over the 

Ohio River basin or the Canadian province of Ontario. In 

contrast, trajectories for the unpolluted case showed that air 

masses lingered above the western Atlantic Ocean. 

7,2, SPECIAL PROJECTS 

7,2.1. SlJU'URMoNITORlNGATMLO 

AQG began a sulfur gas monitoring project at MLO in 

March, 1988. This study was set up to test the following 

hypotheses: 
(1) ALmospheric sulfur is a surrogate for volcanic 

contamination at MLO. 

(2) The background aLmospheric sulfur concentration in the 

free troposphere can be successfully measured at MLO. 

A CSI real-time total sulfur gas monitor was installed at MLO in 

March 1988, and a TECO real-time S02 gas monitor was 

installed in November 1988. The CSI device measures all sulfur 

gases, has a detection limit of 1 ppbv for I-min samples, and has 

a response lime of 10 seconds. The TECO device measures 

only 502, has a detection limit of 0.1 ppbv for I-min samples, 

and a response time of 1 minute. The two instruments are 

described by BoatrruUl et al. [1988}. 

Figure 7.10 shows the history of volcanic sulfur events at 

MLO from June 1988 to January 1989 as measured by the CSI 

device. No significant seasonal trend was evident. The 

following conclusions were reached with regard to hypothesis 1: 

(1) Sulfur gas events with a volcanic origin occurred 32 

times between June 1988 and January 1989, an average of one 

event every 7.7 days. 

(2) These events began about 2200 UTC and ended after 

several hours. 

(3) The largest I-h-average sulfur concentration observed 

during any event was 34 ppbv. The largest event-average sulfur 

concentration was 18.1 ppbv. 

(4) Nearly all the sulfur events were associated with 

northerly winds and smaU dew point depressions. This 

suggested that the events were occurring when marine boundary 

layer air reached the observatory. 

Figure 7.11 shows the sulfur gas concenlration observed with 

the CSI inslrUment and the S02 concentration observed with the 

20 

II) 15 I: 

o 

:;::: 

1: '" 

~ 10 .c 

o 

'0 

'It 5 

o 

6 7 8 9 10 11 12 1 

Month 1988 1989 

Fig. 7.10. History of volcanic sulfur events at MLO from June 1988 

through January 1989. 

61 

TECO instrument during December 1988. Also shown is the 

ratio between the concenlrations measured with the two devices. 

The CSI trend is characterized by occasional volcanic events 

interspersed between long periods of quiescent cyc1ic behavior. 

The TECO trend is characterized by occasional volcanic events 

interspersed between long periods of nearly Oat signal. The 

following conclusions were reached with regard to hypothesis 2. 

(1) The TECO S02 gas monitor, installed in November 

1988, measured concentrations of 0.1-0.1 ppbv, except during 

volcanic events. 

(2) The CSI total sulfur gas monitor, installed in March, 

1988, measured concentrations of 0.1 to nearly 3 ppbv, except 

during volcanic events. 

(3) The ratio between SOl and total sulfur approached 1 

during volcanic events. 

(4) When air was sampled fTom above the marine boundary 

layer, S02 concenlrations remained between 0.1 and 0.3 ppbv. 

However, total sulfur increased dramatically. This resulted in 

the 502 to total sulfur ratio being <0.1 at times in the free 

troposphere. 

15 

CSI 

,- J ~ I ~ 

-'" 10 ~ c ~ 

Q 

~ " g 

• 5 u 

, , II c 

-1 \ nj" J 

a 

<.) 

,... ~, .. {t·.l lV l~ -f ..r'[""{rj '.> "r'_i .A /- J{v~,J 1\,,( 

336 340 344 349 352 356 360 364 368 

15 i TEGO 

,-

~I ~ 

0. 

;; 10 c 

.2 

;; jl 

" • u 5 ~ I c 

a -; <.) 0 

o 

336 

-b.= ___ 

340 

=_= ..

344 

_ 348 352 356 I"",-, II}I",=J ~-,-,I,--",,-~ 360 364 368 

, TEGO/GSI 

~I· i I Ii I II 

05 ~ I I il tl) i . h I 

= I ... M'iI Iln J nl 'l Jl lill 1 ,I\,j\-, ;\ .cj,,"\~ ,.!i"I\ \,., .)\) ~1 '\vl, "-

0+..:..:.--_.;:::::'-'-_......:c_W'=""'-_-""L.-.j 

----Oay -of Year --- ~ Fig. 7.11. Sulfur gas concentration observed with the eSI instrument 

and S02 ooncentration observed with the TEeD instrument, and the 

ratio between them, during December 1988. 
7.2.2. BLUE RIDGE Fumrrs 

In connection with the AQG's participation in the Aircraft 

Monitoring for Diagnostic Model Evaluation project in the 

northeastern United Stales in August 1988, a sub·project was 

undertaken to provide some comparison between aircraft and 

surface measurements. Two flights were made on August 16, 

1988, with the NOAA King Air aircraft. These nights included 

traverses at 2400·3000 m above sea level between the aircraft 

base at Harrisburg, Pennsylvania, and surface research sites 

from two projects (ECP and MCCP) from central Pennsylvania 

to northern Georgia. 

Vertical profiles were flown over each of the five sites, the 

lowest altitude at each location being about 152 m above ground 

level. The sites were (1) Scotia (ECP), ncar State College, 

Pennsylvania, operated by the NOANAL, (2) Shenandoah 

(MCCP), in the Shenandoah National Park, Virginia. operated 

by the University of Virginia, (3) White Top Mountain (ECP), 

in southwest Virginia, operated by the Tennessee Valley 

Authority, (4) Mt. Mitchell (MCCP), near Asheville, North 

Carolina, operated by North Carolina State University. and (5) 

Brasstown Bald (ECP). in northern Georgia. operated by the 

Georgia Institute of Technology. In addition, vertical profiles 

were flown over the Scotia site during flights on August 21. 22, 

and 26. 

Measurements from the surface sites were found to be 

generally lower in the concentrations of °

3, So.l' HzOz' and 

NOy. Detailed analyses have been made of the data from the 

Scotia sileo The best comparison between ground samples and 

aircraft data is expected lo be obtnmc.d by comparing 

atmospheric secondary products (0). H20 2• sulfate, and nitrate}. 

These species arc produced in the atmosphere and have 

formation times of about 2-50 hours. This time is long with 

respect to the usual boundary layer mixing times; thus the 

concentrations wilhin the planetary boundary layer should be 

fairly unifonn. Comprehensive comparison of aircraft and 

surface data at Scotia was possible only with 0); H20 2 

measurements aboard the aircraft provided supplemental 

information. 

0) concentrations aloft were. with few exceptions, higher by 

3-25 ppbv than those measured at the surface. The lowest 

altitude aircraft measurements were 3-5 ppbv higher than those 

at the surface during tJuee of the four sampling nights over the 

Scotia site (August 16, 22, and 26); on August 21, 0) levels 

measured from the aircraft at the lowest flight altitude were 

nearly 10 ppbv higher than those at ground level. Slightly 

higher concentrations at the lowest aircraft sampling altitude can 

be related to deposition of 0) to the surface. especially during 

lhe day when convective activity was at a maximwn. 

On each of the four flights, 0) concentrations were nearly 

uniform within the planetary boundary layer. Fluctuations 

measured at the two lowest aircraft profile altirudes were less 

than 5 ppbv around the mean; 0) time series for the surface and 

the two lowest aircraft altitudes for each of the four sampling 

flights showed no break in the 0) trace between the lower 

sampling level (950 mb) and the upper part of the mixed layer 

(approximately 890 mb). This observation suggests that the 

ground-level data provide a good indication of the 0) distribution within the planetary boundary layer during the day. 

Again with the exception of the profile taken on August 2 1, 

0) concentrations in the free troposphere (above 850 mb) were 

higher, occasionally by as much as 30 ppbv, than lhose observed 

inside the mixed layer. Likewise, H20 2 concentrations were 

higher in the free troposphere, compared with the mixed layer, 

on all flights, in spite of the fact that the dew points were much 

lower at those altitudes. The high 0) levels in the free 

troposphere did not correlate with primary pollutants (S02' NOy' 

and hydrocarbons), which were significantly lower at the higher 

altitudes. Thus the elevated concentrations of the secondary 

pollutants (0) and H20~ in the free troposphere may have been 

related to aged pollution parcels (one or more days), in which all 

primary pollutants had already been oxidized. 

On August 21, boundary layer 0) concentrations measured 

by aircraft were about 70 ppbv, approximately 10 ppbv greater 

than those measured at the surface or in the fTee troposphere. 

These boundary layer concentrations were also lhe highest 

values measured during the four profile flights, and were 

correlated wilh elevated boundary layer S02 levels 

(approximately 5 ppbv); this indicates that relatively fresh 

anthropogenic pollution was present, in which 0) generation 

was occurring. The difference between the surface and aircraft 

measurements was greater than that observed on the other 

flights, indicating that boundary layer mixing was not as 

complete as at the other times. 

7.3. REFERENCES 

Barth, M.C., D.A. Hegg, P.V. Hobbs, J.G. Walega, G.L. Kok. B.G. 

Heikes, and A.L Lazrus, Measurements of atmospheric gas-phase 

and aqueous-phase hydrogen peroxide concentrations on winter on 

the east coast of the United States, Tellus, 418, 61-69, 1989. 

Boatman, J.F., M. Luria, C.C. Van Valin, and D.L Wellman, 

Continuous atmospheric sulfur gas measurements aboard an aircraft: 

A comparison between the flame photometric and fluorescence 

methods, Almas. Enyiron., 22(9 J, 1949-1955, 1988. 

62 

Boatman, J.F., R. Artz, L. GUIlter, and H. Sievering, Intercomparison of 

AQG-aircraft and AOML-ship chemical and meteorological data 

during CASE/W ATOX, Proceedings GCElCASElWATOX DOla 

Workshop, Miami, FL. September 11-15, NOAA/ERUAOML, 

1989a. 

Boatman. J.F., D.L Wellman. C.C. Van Valin, R.L. Gunter, I.D. Ray, 

H. Sievering, Y. Kim, S.W. Wilkison, and M. Luria. Airborne 

sampling of selected trace chemicals aboye the central United States. 

J. G,oph]s. Res., 94(04), 5081-5093, 1989b. 

Chang. 1.S., R.A. Brost. I.S.A. Isaksen. S. Madronich, P. Middleton. 

W.R. Stockwell, and C.1. Walcek, A three-dimensional Eulerian acid 

deposition model: Physical concepts and formulation. 1. Geophys. 

Res., 92,14,681-14,700,1987. 

GWeue, D., and K. Hansen. Spatial and temporal variability of dust 

emissions in the United States, J. Geophys. Res., 94, 2197-2206, 

1988. 

Heikes, B.G., G.L. Kok, J.G. Waiega, and A.L Lazrus, 1-1 2°2' 0), and 

S02 measurements in the lower troposphere over the eastern United 

States during fall,J. GMphys. Res., 92,915-931, 1987. 

Kim, Y J., H. Sievering, and J. Boaboan, Airbome measurement of 

atmospheric aerosol particles in the lower troposphere oYer the 

cenlral United States, 1. Gtophys. Res., 93, 12,631- 12.644, 1988. 

Kim, Y., H. Sievering. J. Boatman, and S. Wilkison, Determination of 

water mass and dry mass composition of CASE/W ATOX marine 

aerosols, Proceedings, GCElCASElWATOX Dala Workshop, Miami, 

FL, September 11-15, NOAAIERUAOML. 1989. 
Kleinman, LI., Photochemical fonnation of peroxides in the boundary 

layer, 1. Geophys. Res., 9/, 10,889-10,904, 1986. 

Lazres, A.L, G.L Kok, lA. Lind, S.N. Gillin, B.G. Heikes, and R.E. 

Shetler, Automated fluorimetric method for hyd rogen peroxide in 

the air, AMI. Chern., 58, 594-597, 1986. 

Logan, l.A. , M.1. Prather, S.C. Wofry, and M.B. McElroy, Tropospheric 

chemistry: A global perspective, J. Geophys. Res., 86, 7210-7254, 

1981-

Luria, M.L, C.C. Van Valin,l.D. Ray, and 1. Boatman, The relationship 

between ozone and hydrogen peroxide: Field observation and model 

evaluation, Proc. of the Quadrennial Ozone Symposium, August 

8·/4, 1988, Cottingen, FRG, A. Dccpak Publishing Co., Hampton, 

VA,1 989. 

Meaghe r, I.F., E.M. Bailey, and M. Luria, The seasonal variation of the 

atmospheric S02 to SO; conversion rate, J. Geophys. Res., 88, 

1525-1527, 1983. . 

MueUer, P.K., G.1-I. Hidy, K. Warren, T.E Lavery, and RL Baskett, 

The occurrence of atmospheric aerosols in the nonheastem United 

Slates, Ann. N.Y. Acad. Sci., 338, 463-482,1980. 

Sievering, H., G. Ennis, E. Gonnan, and C. Nagamoto, Size distributions 

of excess sulfate, nitrate, and chloride defici t during 

CASE/WATOX: A case for the heterogeneous conversion 

mechanisms, Proceedings, CCEICASEIWATOX Data Workshop. 

Miami, FL, September 11-15, NOAAIERUAOML, 1989. 

Van Valin, e.e., J.D. Ray, J.r. Boatman, and R.L Gunter, Hydrogcn 

peroxide during winter in air over the south -central United Slates, 

Geophys. Res. utI., 14, 1146·1149. 1987. 

63 
8. Nitrous Oxide and Halocarbons Group 

J. BUTLER (Edi,o,), J.W. ELKINS, T.M. THOMPSON, B.D. HALL. AND c'M, BRUNSON 

8, I. CONTINUING PROGRAMS 

8.1.1. FLASK SAMPLES 

Sampling and InstrumenJation 

During 1988, air samples were collected in pairs of O.3-L. 

Summa-treated, stainless steel cylinders each week at BRW, 

NWR, MLO, and SMO. The samples at spa were collected 

each week only during January, November, and December, 

when the Antarctic interior was accessible by aircraft. In 

addition. a new flask sampling effort was instituted at the Alert 

(ALT) station of the Canadian Atmospheric Environment 

Service, in the Northwest Territories. where nask pairs were 

filled with air on a 1-2 week schedule beginning in February. 

All flask samples were shipped to our central laboratory in 

Boulder, Colorado, where they were analyzed by EC-GC for 

N,O, CFC·12 (CCI,F,), and CFC-II (CCI,F). 

Primary calibration lank no. TI088 was retired from service 

in December 1987 and was replaced by alumimun cylinder 

62631 that had been treated wilh Aculife (SCOIt Specialty Gases, 

Plumsteadville, Pennsylvania) and filled with dried air from 

NWR. N20, CFC·12, and CFC-ll concentrations in the new 

lank were compared with those in T3088 in September and 

October 1987, and again in May 1988. No significant drift was 

apparent from lhese intercomparisons. 

An automated flask analysis system was designed, and 

construction of it was begun in 1988. In the past.. each flask was 

analyzed manually on one GC system. but with this new system, 

up to 10 flasks can be analyzed in any sequence, and reference 

gases can be interspersed as needed. Three GCs will be used to 

analyze N,O (affected by CO,), N,o (unaffected by CO,), 

CFC-12. CFC·II, CFC-113 (CCI,F.CCIF,), chlomform 

(CHCll ), meLhylchloroform (CH3CCI3), and carbon tetrachloride 

(CCI4 ). A desk·top computer will be used to control the 

chromatographic system as well as to collecl, analyze. and store 

the data. The hardware has been purchased, and most of the 

controlling software has been written. 

Some unusual samples were collected or reported in 1988. 

The first came from the second boat pit of Khufu's pyramid in 

Egypt in October 1987. Tans e/ al. [1988) explained the air 

sampling procedure and measurement results. It was hoped that 

the chamber would contain ancient air, but the halocarbon 

composition showed that the pit was not sealed with respect to 

the outside atmosphere. A stability study was initiated using 

various types and sizes of containers (aluminum and stainless 

steel) to find a suitable generic flask for all compounds 

measured by GMCC for ambient levels of COl' CH4 , N20, 

CFC-ll, and CFC-12 over time. The electropolished stainless 

steel and aluminum flasks were stable for ambient levels of 

CFC·ll and CFC·12 for storage under 35 days, but all other 

compounds showed significant loss or gain with time for lhese 

unusually wet samples [Tans el al., 1988]. 

The second set of unusual samples was collected at SPO on 

January 24. 1988. The samples in two 1.0-L flasks were 

pressurized to 150 kPa. returned to Boulder. and scaled in a time 

capsule in the foundation of the new CIRES building on the 

University of Colorado campus. These samples will be 

recovered in 50·100 years for reevaluation of their contents. 

Results 

Data [rom flasks collected at BRW, NWR, MLO. SMO, and 

SPO from 1977 through 1988 show a mean, global growth rate 

of 0.68 ppb yr' for N,o (Figure 8.1),16.1 ppt yrl fo, CFC-12 

(Figure 8.2), and 9.8 ppt yr' fm CFC-II (Figure 8.3). 

Preliminary 1988 monthly mean data are tabulated in Table 8.1. 

The CFC·ll and CFC·12 data show that concenlrations are 

rising over the past few years at a rate Slronger tllan that seen in 

the earlier record. Since calibration gas standards have been 

changed in this period and insufficient time has gone by to 

delennine calibration tank long-tenn stability or drift characteristics, it is uncertain whether the stronger rise is real. being a 

response to increased chemical usage and release into the 

atmosphere, or a vagary of the new standard. 

Data from flasks collected at AL T were often erratic; many 

pairs did not match well. This was worse for CFC-ll than it 

was for CFC·12. Consequently, only flask pairs with concentrations that agreed have been retained for subsequent analysis. 

Results from ALT compare favorably with those from BRW, 

although there are slight differences (Figure 8.4). These 

differences can be ascribed to the large distance between the 

stations and the different air masses that move in and across tlle 

Arctic basin. 

8.1.2. RITS CO\TI\'l:OUS GAS CI[ROMATOGRAPII SYSTHIS AT 

GMCC BASELINE STATIONS 

Sampling and Instrumenlation 

64 

In·situ measurements of CFC·ll, CFC-12. CFC-113. N20, 

CH3CCI

3, and CC14 were made 8 times per day at three GMCC 

baseline stations, BRW, MLO, and SMO, and 12 times per day 

at SPO. Instrumental precision has consistently been better than 

0.3% for NlO and between 0.5 and 2% for the rest of the 

compounds. In mid·1987 measurements of N2

0 were begun 

using a Porapak Q column. and the precision has been greatly 

improved because there is no known CO2 effect, and no 

interfering peaks on the chromatogram (Figure 8.5). 

In November 1988. the MLO and SMO systems were 

modified so thaI all three columns could be backflushcd. 

Previously. only the N20 GC was equipped for backilush 

operation. The backIlush modifications at BRW will be 

completed in early 1989. Backflushing the columns should 

improve the precision of the measurements by allowing 3D-min 

runs instead of 60+min runs. Along Wilh the backIlush 

modifications. an HP hierarchical filing system was installed to 

speed up data storage. It is anticipated that 30-min runs will 

begin early in 1990. 
, " 

, I 0 

, 00 

, I 0 

, 00 

, I 0 

, 00 

, 10 

, 00 

, I 0 

, 00 

ORW 

NWR 

MLO 

S MO 

s pa 

Slone ~ 0.62 003 ppb ye" 

Slope 066 0.03 ppb ~'r-' 

Slone .. 0.69 0,03 nnb vr-' 

0.0 ... Dob vr "' 

, .' 2 9 0 JL-__________ -~·-c!. 'En!.'_= 0'., 

·~~'C~!!~·0'2_EEnn2~L"·~-~·,_l 

77 78 79 ao 8 1 82 83 84 85 86 87 88 

TIME (YEAR) 

Fig. 8.1. Monthly mean concentrations of NzO from the NOAA/GMCC 

nask (+) network (C02 and H20 corrected). The SPO plot also shows 

monthly means (0) from the old GMCC in-situ GC. The trends and ±2 

standard deviations are also shown. 

, 00 

l ~ 0 BRW . , 00 

~ '" Slo ne - 9 .98 • 0 I DOt 'roO 0.. 

0.. 

" 0 NWR ~ 

c , 00 

a '" Slone 9.0 I 12 not , 0 YI'-' = 

-= " 0 MLO - : 

<= , 00 ~ 

~ 

<= '" Slope ~ 9 8, 0 I DDt Yr" • a SMO '-' " 0 , 00 

I '" Slo De - 97. 008 ppl vr-' '-' ""- , " spa '-' , 00 

'" S lone - 9 25 100 , 0.46 DOt Yr" ' 

77 78 79 50 61 82 63 64 65 66 67 68 

TIME (Y EAR) 

Fig. 8,2. Monthly mean concentrations of CFC-12 from the NOAA! 

GMCC nask (+) network. The SPO plot also shows monthly means (0) 

from the manually operated GMCC in-situ Gc. The trends and ±2 

standard deviations are also shown. 

New regulators were purchased and installed in 1988, solving 

many of the contamination problems. A contaminant still elutes 

between CH)CCI) and CCl4 on the SP2100 GC column in one of 

the BRW standards, and one of the MLO standards has a large 

amount of CFC·} 13. The major problem with the contaminants 

is that they make it difficult to integrate the chromatogram peaks 

consistently, and the precision suffers as a result. The precision 

can be improved for CH)CC1) and CCl4 by calculating 

concenlrations from peak heights instead of from peak areas. In 

the future, both peak heights and peak areas will be computed 

and stored for all components measured by the RITS GC 

system, and old data will be reintegrated and both areas and 

heights will be stored. 

65 

, 00 

, 00 

" 0 

, 00 

" 0 

BRW 

S lope _ 16 16 I 0.23 ppt or·' 

NWR .......... 

S l ope = 15133 • 03 ool VI'-' 

MLO 

.----"'~.~- .-

S lope _ 15 ·19 02·1 ppl yr-' 

S}.I O 

,00·~ 1 ==~S lope -~~ 16 ·15 • 0 1 ·1 ppt VI'" 

s pa 

' 

"OL~~:J 00 2 0 0 S lope"" 160-1 • 0.>\7 Pill yr" 

-n 78 79 80 81 62 83 6-1 85 86 67 66 

WIE (YEAR) 

Fig. 8.3. Monthly mean concentrations of CFC-It from the NOAA! 

GMCC fla sk (+) network. The SPO plot also shows monthly means (0) 

from Ihe old G.MCC in-silu GC. The trend s and ±2 standard deviations 

are also shown. 

-" 3 3 0 0. 

0. 3 2 0 

'? 3 I 0 z 300 . 

~ . 

0. 

0. 0\ 75 

" 

I 0\ 50 u 

"- " 25 u 

~ 

295 0. 

0. 

2 ? 0 I 

u 2 -1 5 "-

u 220 

ALT 

......... -.. ..... --, -- • .-. 

a 

••• .- -... - - -

b . 

... .-- . - • _ 0 

C 

FM ,\MJJA SOND 

1988 

. 

Fig. 8.4. Average concentralions for (a) N20, (b) CFC· 12, and (c) 

CFC·tl from flask pairs collected at ALT. The dotted line is a spline fit 

to BRW flask data for comparison. 

A modified RITS GC was set up and tested at SPO in 

February. The system consisted of two Shimadzu Mini-2 GCs 

that measure the concentrations of N20, CFC-12, CFC-II, 

CH,CCI,. and CCI, on an hourly basis, An ffiM XT clone 

computer was set up to allow automated data transfer from the 

two HP3390 integrators to a floppy disk. Data from the disk are 

then transferred weekly via satellite to Boulder. 

Results 

In 1987 an apparent increase of 18 ppt yrl was reported for 

CFC-12 at BRW (Figure 8.60). It is now apparent that this was 

the result of seasonal fluctuations in the CFCs, perhaps from 

European air masses. The seasonal variation at BRW is also 

more apparent in the CFC-l1 data (Figure 8.6b). 
TABLE 8.1. 1988 Monthly Mean Concentration for Np (ppb by mole fraction in dry air), CFC-12 (ppt), and CFC-II (ppt) 

from Flask Pairs Collected at BRW, NWR, MLO, SMO, and SPO 

NzO 

1988 BRW NWR MLa SMa spa BRW NWR 

Jan . 308.7 309.5 307.2 305.4 308.0 443.9 440.9 

Feb. 308.1 308.3 308.1 305.8 306.4 444.2 437.2 

March 309.8 309.8 306.5 304.3 446.6 447.8 

Arpil 308.6 307.5 308.0 447.8 444.6 

May 308.4 308.1 307.2 305.1 443.8 445.8 

June 308. 1 307.7 306.8 446.8 445.6 

July 307.5 309.2 308.3 304.3 446.8 454.2 

Aug. 306.9 309.0 307.0 305.5 448.6 455.4 

Scpt. 308.9 308.1 306.7 304.6 457.0 450.9 

Oct. 308.5 308.8 307.9 304.1 456.7 448.5 

Nov. 309.0 310.4 308.9 303.7 469.6 459.1 

Dec. 309.6 309.6 307.3 306.2 307.1 462.0 451.2 

These dala arc. provisional, pending flllal calibralion. 

The year 1988 was the first complete year of CH3CCl1t and 

eel, measurements from the GMCC baseline observatories. 

Although it has been possible to calculate crude atmospheric 

growth rates from this limited data set, the results should be 

considered tentative until measurements over a larger time span 

arc obtained. Also, some analytical problems, which may have 

an effect on the overall accuracy of these numbers. are still 

being resolved. 

On the basis of only 1 year of observations at MLO (Figure 

8.7), the concentration of atmospheric eel, does not appear to 

be increasing significantly; CH)CCI3, however, does seem to be 

growing at about 4% per year, a finding that is confounded by a 

contaminant interfering with the measurement of this com308 

304 

-------- ...D 

0... 

0...308 

'--..-/ 

304 

0 N 

:z: 

308 

304 

BRW I I I I l-+-f--+-

.-

, . ". 

MLO 

!-;f-f->-I I I I I I I I I I I-I-+-f--+-

. :' .• !.:" !,'.tD:~_4'4";;''';''' ~~~.~ • "-:~ ~':?Ii .·,r'r 

• • 'S M 0 

J J A SON 0 J r M A M J J A SaN 0 

1987 1988 

Fig. 8.5. N20 concentrations from nask pair samples (0) and daily 

means from the in-situ RITS GC (+), at BRW, MLO, and SMO. 

66 

CFC-12 CFC-Il 

MLO SMa spa BRW NWR MLa SMO SPO 

428.3 415.7 405.1 263.5 260.3 248.8 242.7 

433.1 418.8 265.3 258.5 254.2 243.9 

430.9 415.4 266.3 263.5 250.3 238.0 

438.1 424.1 268.5 262.1 256.2 247.0 

438.3 421.3 265.6 269.4 256.9 243.7 

438.6 266.1 263.8 257.9 

442.8 426.9 265.6 267.9 257.7 246.2 

442.0 426.8 267.3 270.0 259.1 249.2 

445.7 427.3 268.6 264.5 261.8 245.8 

446.0 433.5 271.9 263.8 262.0 249.9 

449.2 437.7 423.4 277.7 272.7 266.9 251.5 246.9 

453.7 434.0 423.1 277.3 268.0 258.3 244.6 

pound. As for the CFC-1l3 estimates. the estimated growth 

rates for CCI, and CH)CCI) will be refined considerably as our 

in-situ systems remain on ]jne long enough to collect a few 

years' data and as lingering contamination problems are 

resolved. 

8.1.3. Low ELECTRON A TIAOIMENT POTENTIAL SPEOES 

A temperature-programmable. dual-channel, EC-GC was 

pun:hascd and installed for the measurement of LEAPS gases, 

specifically HCFC-22 (CHCIF,), CFC-I13, and the Halons, 

H-1301 (CBrF,) and H-1211 (CBrCIF), in our Boulder 

laboratory. The GC was filted with a programmable cryofocusa. 450 a. 

'" 425 

t .' 

~ 400 u 

a , , " QI)~ , ~'. , . ',. 

" 

i-+ri-l-ri-l-ri-l-rH-J-J I I I I I I I I 

a. 275 a. 

250 , 

~ 225 u 

Jon J u I Jon J u I 

1987 1988 

Fig. 8.6. (a) CFC-12 and (b) crC-lt concentrations (ppt) at BRW 

from the in-situ RITS GC. Note the apparent elevation in crc 

concentration from laiC October to ISle May. 
200 0.. 

0.. 

- 180 u 

~ 

:r: 

u 1 60 

108 

~ 106 

u 

u 

10 4 

102 

a ~ 

•. _!"!. • 

£..-: 

"~ -. .... -. 

. 

I-+--+--!--t-I--~-+--+ --+-

b 

. : - -.:-

Jon M a r M oy Jut Sep Nov 

1988 

Fig. 8.7. (a) CH)CCI) and (b) CCI4 concentrations 81 MLO in 1988 

from the in-silu RITS GC. 

ing unit for concentrating and injecting atmospheri c gases. This 

unit, designed for injecting gases adsorbed to packed tubes. was 

modified to allow the direct injection of up 10 500 mL. As a 

result, clcctrophilic gases can be measured to levels as low as 1 

ppt. 

A nrunbcr of standard gases were tested on the GC with a 

silicone oil column (Chrompack CP-Sil-5. 1.2 ~) set to a 

tcmp:rature range of -60·C to +11 O·C. The column eluted all 

gases of interest from H-nOI (boiling point = -59"C) to CCI4 

(boiling point = 77 "C), with reasonable separation of peaks. 

Peaks were identified and response factors determined for N20, 

H·1301, HCFC·22, CFC· 12, CH,CI, HFC·134a (C,H,F.), 

H· 121 I. CFC· II, HCFC·123 (CF,CHCI,), CH,Cl" CFC·I13, 

50 =- HC~23 ~\ \ 0", FC'113 \ \ CCI, 

o '" "- CH,CCI, 

C'11 CH ,CI, CHCI, 

·50 ~~~~~~1 34 0> ~ CH,CI ,§; CFC·12 

'0 -100::o....N 0 CFC'22 co l H.1301 

·150 -

30 

Retention Time (min) 

Fig. 8.8. Boiling point curvc for !he chromatographic separation of 

natural gases and halocarbons on a silicone oil-based, capillary column 

(Chrompack CP-SiJ-5, 1.2j.U1l ; 0.53 mm x 50 m). NOle similar retention 

times for proposed replacement halocarbons (CFC-134a and Here123) and the compounds they are 10 replace (CFC- 12 and ere-II). 

CHell' CH)CClJ• and CCI4 (Figure 8.8). Two of these gases, 

HFC· 134a and HCFC·123, have been proposed as replacement 

halocarbon, for CFC·12 and CFC· II. 

The first air samples for LEAPS gases were collected from 

NWR in November, beginning OUT long-Ienn monitoring 

program for lIlc four LEAPS gases. The GC has also been used 

to measure Lhc composition and contamination of industrial 

solvents used for cleaning regulators and fiuings purchased by 

our laboratory, and to identify contaminants in cylinders of 

commercial carrier gas, "zero air" collccted at NWR, and 

standard gases filled at NWR. Evaluating alternative, analytical 

columns and installing new, high-pressure pumps at the 

observatories to provide sufficient samples for replicate meaTABLE 8.2. Summary of GMCC Gravimetric Standards Prepared in 1988 

Sel Compounds QuanlilY Conccnlralion Range Prepared for 

I CO2,N2O 5 ppm NOAA/RITS 

2 CFC·12 8 ppm, ppb, ppl NOAA/RITS 

3 CFC·12, CFC·I I, CFC· I \3, CII,CCI,. CCI., CIICI, 3 ppb, PI" NOAA/RlTS 

4 CFC- 12, CFC-l l , CFC-ll3, CH]CO], CCI

4, CII]Br 3 ppl NOAA/RlTS 

5 CFC·113 3 ppm, ppb, ppl NOAA/RlTS 

6 CFC-113, Halon-12 1l, CFC-22 I ppb NOAA/LEAI'S 

7 CII4 5 0.1 % NOAA/fT·IR/CC 

8 II FC·134a 7 ppm NOAA/FT-IR 

9 IICK·I23 I ppm NOAA/FT-IR 

10 CO, 4 ppb NOAA/GMCC 

II Benzene, isoprenc, pclHanc, I ppm NOAA/AL 

a-pinene, m-xylcnc, 2,2-dimelhylbutanc 

12 lIalon- 12 I 1 ppm OGC 

13 lIalon- 1211 ppm NOAA/ARUldaho FaUs 

67 
surement of LEAPS gases should lead to improvements in 

precision and accuracy of the LEAPS measurements. 

8.1.4. GRAVIMETRIC STA1\'l)ARDS 

Our newly completed gravimetric standards laooratory is 

now capable of preparing gravimetric standards for a large 

variety of compounds at sub-percenl, parts per million, parts per 

billion, and parts per trillion concentrations. Several sets of 

gravimetric standards were prepared for various projects such as 

RITS, LEAPS, and Ff-IR, and other groups, including 

NOANARL Idaho Falls, NOANAL, and OGe (fable 8.2). 

Standard curves were constructed from gravimetric sets of 

N20, CFC-12, CH)CCI), and CCI4 . The precision for these 

curves was 0.4 ppb. 1.6 ppl, 2.2 ppt, and 1.3 ppl, respectively, 

where precision is defined as the average difference between the 

gravimetric concentration and the concentration predicted by the 

standard curve (Figures 8.9-8.12). A set of CFC-ll and 

0 

0 

~ 

. 

1.2,----------------- -, 

N,O 

1 - OV9 fiC = 0 .4 ppb 

0.8 

0.6 no n- lin e or l it 

0. ' 

0.2 . '.'.' 

a 1/, 1 

" 

I 

100 I 150 

I 

a 200 

pp b 

I 

250 I 

300 

• 

3" 

Fig. 8.9. NzO standard curve prepared from hlJST SR.!\1s and NOAA 

gravimetric standards. A nonnalized detector response is plotted versus 

concentration. 

2 r 

a 

a 

CFC -1 2 

ovg DC = 1 . 6 ppl 

• prepar e d fr o m p u re gos 

J. p rep a r ed fr om pure liquid 

-'- 1 

100 200 300 t OO 500 600 700 800 900 1000 

p pl e r C- 12 

Fig.8.lD. CFC-12 standard curve for parts per trillion concentration 

levels, showing good agreement between two methods of preparation. 

CFC-II3 standards will soon be prepared, and all RITS 

compounds will be reported on the NOAA scale. CFC-II and 

CFC-12 are currently reported on the OGC scale of 1985. The 

nonlinear response of N20 on an ECD was investigated by 

comparing NzO gravimetric standards in a 290-ppb range. NIST 

SRMs and NOAA N20 standards were used to construct a curve 

from 44 to 333 ppb (Figure 8.9). A linear extrapolation from a 

response of unity differed by as much as 12.5 ppb from the true 

curve in the 130 to 150 ppb range, but the difference was not as 

significant (lcss than 3 ppb) in the 280 to 320 ppb range. 

Gravimetric standards of CFC-12 were prepared by two 

different methods. Pure CFC-12 gas was diluted to the parts per 

trillion level and compared with parts per trillion standards 

prepared from the dilution of pure CFC-12 liquid. Both sets of 

standards agreed within 1.6 ppt (Figure 8.10). 

A dual-detector Shimadzu GC-8A with a flame ionization 

detector was purchased and will be used to compare standards at 

the parts per million levels. A Perkin-Elmer 3920B GC and a 

CH,CCI, 

a vg 6C=2. 2 p pt 

0 .7 5 

• .. ' 

~ 

~ 

z 0.5 " 

•• ~ .. ' 

.' 

0.25 .,'" 

a " 100 15 0 200 

pp f CH,CC I, 

Fig. 8.1 1. CH3C03 standard curve for parts per trillion levels. 

CC I, 

• ~ 

~ i.5 ~ 

N 

~ 

.. 2 

0 

.. ~ " 0 

0 

~ 0 . 5 

" • NOAA 

• tIBS/NOAA 

a 

a " 100 15 0 200 

p p l cel , 

Fig. 8.12. C04 standard curve for pats per lrill.ion levels showing good 

agreement between NOAA and NIST standards. 

68 
Spectro-Physics SP71 00 GC with electron capture detectors will 7 -,-----------------------, 

be used to compare standards at parts per billion and parts per 

trillion level. This set of GCs will allow us to examine our 

standard sets more closely at each step in the dilution process. 

8.2. SPECIAL PROJECTS 

8.2.1. SOVIET-AMERICAN GAS Al\'D AEROSOL EXPERlMEl\:1 II 

SAGA II in 1988 emphasized filtering and reducing the CFC, 

N20, CO2, and CH4 data collected by automated GCs during the 

3·month cruise. The results were evaluated and presented at 

professional meetings, and a data report describing our 

analytical methods, data reduction, and results was published in 

December (Butler el aI., 1988]. Manuscripts for publication in 

professional journals were begun once the data were finalized. 

8.2.2. FT-IR SPECTROMETER ARCHIVE PROJECT 

As discussed in section 8.1. 1., the goal of finding a generic 

flask for all compounds measured by GMCC has been elusive. 

The FT-IR spectrometer permits archiving the IR absorption of 

almospheric trace gases for future analysis of compounds not 

currently analyzed by GMCC. A solar tracker that permits the 

spectometer to [onow the sun was designed in 1988. It is 

anticipated that the Fr-rR archive project will begin in 1990. 

The principal goal in 1988 was measuring laboratory spectra 

of many important RITS gases, including CH4 and the new 

substitute CFCs. These spectra are required to calibrate the 

instruIIIent fur <iunospheric HH.:asurcmcllts. TIlc spectra were 

also useful in verifying our methods for the preparation of gas 

standards. Figure 8.13 shows a laboratory infrared spectrum 

between 600 and lS00 em· 1 for one of the proposed replacement 

halocarbons, HFC-134a, measured for a sample conlaining 1021 

ppm in air in a IS-cm-Iong gas cell at 300 K. Figure 8.14 shows 

a Beer's law plot for the u4 fundamental band of CH4 at various 

temperatures, where the slope of the line yields the band 

strength value for the compound. For both CH4 and HFC-134a, 

03,--------------------, 

025 

;; 0 2 

. 

o 

.:, II 15 

300 K 

1~ em 1021 ppm 

Wo ... ... number (em -') 

Fig. 8.13. Infrared absorption by one of the proposed replacement 

halocarbons (HFC-134a). 

1;1"' ~ ~ 300K 

6 1<;."" ~n]K 

lriJ.1i1e .>250 " 

'w z 2jO K 

p,,,':.a,on . n 3 K 

s 

2 

'/ 

a 

0.00 0.01 

, 0 

o 0 

0.02 0.03 

PRES·P A TH (em-Jim) 

/

0 

, . 

a 

0 . 0 5 

Fig. 8.14. Becr's law plot of integrated absorbance versus prcssure · 

palhlcngth for the U4 band of CH4 at various temperatures. 

band strength values were not a function of temperature, but thc 

band shape was definitely affected by temperature; the band was 

narrower and absorption greater at lower temperatures. Table 

8.3 shows a summary of all band sLrenglh measurements in 

1988. The GMCC band strength for the u4 band of CH" is 

identical to the value of Varanasi el al. {1983]. The measured 

total band strengths for HFC-134a and HCFC-123 are comparable with toral band strengths for the compounds that they arc 

replacing, CFC·12 and CFC-l1. Since the atmospheric lifetimes 

of the replacement CFCs are shorter (-IS years for HFC· 134a 

and -2 years for HCFC-123) than that of the CFCs (-100 years), 

the potential for the replacement CFCs to produce the greenhouse effect is greatly reduced. 

69 

TABLE 8.3. Summary of Band Strength 

Measurements for RITS Gases 

Total Band Strength 

Compound Fonnula (cm·2 atm· l at 300 K) Refercnce 

Methane 

u" band CI-i4 125 This rcpon 

U4 band CH4 126 Varanasi el al., 1983 

CFC aNi Substitutes 

HFC-134a Cl ll2F 4 3147 This repon 

CFC·12 CCl2F2 3271 Elk.ins el al. 1986 

HCFC-123 Cl HC1l FJ 2379 This repon 

CFC-l1 CCIJF 2417 Elk.ins et a/., 1986 
8.2.3. AIRBORNE GAS CHROMATOGRAPH 

A Shimadzu Mini-2 gas chromatograph was modified for use 

aboard the NOAA King Air research aircraft. The GC was 

designed for measuring halocarbons in the atmosphere at the 

parts per trillion level at 4-min intervals in a pressurized aircraft. 

The GC was configured with a O.6-m Porasil B main column 

and a O.3-m Porasil B backnush column. A carrier gas makeup 

<0 0 

500 

E 600 

. 

, 

:;: 700 

~ 

800 

9 00 

• GC 

• r l ,\, SK 

0 HW R 

-

350 

, 

' 00 

1+ 

. ;~ + 

• + 

~ ;. + 

" 0 

crC -12 (pp l) 

.. 

, 

500 550 

Fig. 8.15. CFC-12 variation with altitude over eastern Colorado on 

December 6, 1988. 

70 

stream and two absolute backprcssure regulators were installed 

at the outlet of the detector to compensate for changes in 

aunosphcric pressure. 

One lest night was conductcd over eastern Colorado on 

December 6, 1988. CFC- 12 was measured at various altiludes, 

and flask samples were collected and compared with the GC 

data. Figure 8.15 shows CFC-12 as a funcLion of ahitude. This 

test night provided valuable preliminary information regarding 

the capabilities and limitations of an airborne EC-GC. 

8.3. REFERENCES 

Butler. J. II.. l. W. Elkins, C. M. Brunson, K. B. Egan. T. M. Thompson, 

T.1. Conway, B. D. lIall, Trace gases in and over the west Pacific 

and ea st Indian Oceans during the El Nino-Southern Oscillation 

event of 1987, NOAA Dala Rep. ERL ARL-J6, 104 pp., NOAA Air 

Resou rces Laboratory, Boulder, CO, 1988 . 

Elkins, l.W., R.L Sams, and J. Wen, Measurements of the temperature 

dependence on the inrared band strengths and shapes for halocarbons F- II and F-12, NOlional BunQu of Slandards (U.S.) Report 

553·K·86, 30 pp., Gaithersburg, MD, 1986. 

Tans, P. P., J. W. Elkins, and D. R. Kitns, Air sampling procedures and 

measurements of the air composilion of the second boat pit of 

Khufu's pyramid,NOM Tech. Memo. ERLARL.163, 21 pp., NOAA 

Air Resources Laboratory, Boulder, CO, 1988. 

Varanasi, P., L.P. Giver, and F.P.J. Valero, Thermal infrared lines of 

methane broadened by nitrogen at low ternpcranres, 1. QllOnl. 

Speclrosc. Rad. Trans. 6, 481 -490,1983. 
9. Director's Office 

9.1 . ALKALINE AEROSOLS i'ROGRA,\1, 

ALKALINE AEROSOLS L-"'VENTORY 

D. A. GILLETTE 

9.1.1. INTRODUCllON 

The NAPAP Interim Assessment [Placet and Streets, 1987J 

concluded Ulat "emissions of alkaline substances can 

significantly influence precipitation acidity by neutralizing some 

fraction of the acids," and that alkaline emissions may have an 

especially substantial effect on the pH of wet deposition in the 

western United Slales. Because of the importance of alkaline 

materials to rain chemistry. we have attempted to estimate !he 

emissions of these materials in the United States. In previous 

work [Evans and Cooper, 1980] the largest sources of alkaline 

aerosols have been estimated to be "open" sources (sources too 

great in extent to be controlled by enclosure or dueling). These 

sources are wind erosion of soils, including dust devil 

emissions; road dust generation by vehicles; and dust emission 

from tillage operations. 

These estimates for the open sources of alkaline particles 

were used in tlus study to form an inventory for elemental 

alkaline emissions of calcium, potassium, magnesium, and 

sodium. Fluxes of the alkaline elements were expressed in 

tenns of equivalent fluxes of hydrogen so that the alkaline 

fluxes could be easily compared with acid precursor fluxes. 

That is, elemental fluxes were divided by atomic weight and 

mUltiplied by valence; for example, calcium fluxes were divided 

by 20. The mapping of results is consistent with the mapping 

format of the RADM. 

9.1.2. METHOD OF ESlnlAllNG ALKAllNE DUST PRODUCllON 

Wind Erosion Emissions 

A physically based model of dust emissions was discussed in 

the 1987 GMCC Swnmary Report [Bodhaine and Rosson. 

1988]. The model was used to compute expected total wind 

erosion dust emissions for soils of the United States. The 

alkaline emissions were then estimated from the total dust 

emission estimates by multiplying the dust emissions by the 

fraction of the soil mass for the alkaline elements calcium, 

potassium, magnesium, and sodium and by an enrichment 

factor. Average soil fractions for those elements were 

calculated using the soil composition data of Boerngen and 

Shacklette (1981]. The enrichment factor (a ratio of the 

percentage of an alkaline element in particles smaller than 10 

}lm to the percentage of alkaline composition for all sizes of the 

soil) was needed because only partic1es smaller than 10}lJT1 were 

suspendabJe for long periods of time, and it is known that the 

composition of soil varies as a function of size. The enrichment 

factor was calculated by using the soil texture data in the USDA 

National Resources Inventory data base and composition. 

versus-size measurements of Gatz et al. [1986] that show that 

virtually all alkaline mass is associated with the silt and clay 

fractions of the soil (that is, partic1es smaller than 50 so that the 

alkaline fluxes could be easily compared with acid precursor 

fluxes, }lm). 

Dust Devil Emissions 

We estimated total suspension of alkaline material by dust 

devils [Gillette and Sinclair, 19901 by generali zing the aircraft 

measurements of SillClair [1990}. In Sinclair's aircraft 

experiments, simultaneous measurements were made of partic1e 

concentration and venical velocities in the updrafts of several 

dust devils at altitudes of 142 and 300 m. The proouct of the 

average partic1e COnCenlTation in the updraft limes the average 

vertical velocity gives the mean vertical flux for the dust devil 

being sampled. Dust devils were classified into four different 

sizes (small, medium, large, and extra large), as was done by 

Sinclair [1975], and the means of the experimentally detennined 

vertical mass fluxes were found for each of these dust devil 

classifications. These mean fluxes were then used to calculate 

total vertical fluxes of dust and vertical fluxes of dust smaller 

than 25 }ll11: the mean dust flux for dust devils of all four classes 

was multiplied by number of devils during the year for a 16 k.m 

by 16 km area near Tucson, Arizona [Sinclair, 1969], 

supplemented by the data of SflOW al1l1 McClelland (1 988] for a 

test area near Alamagordo, New Mexico. 

These data were then generalized to areas in the Unjted 

States as defined by climatic and vegetative classifications [for 

details, see Gillette and SillClair, 1990]. Fluxes of alkaline 

elements calcium, potassium, magnesium, and sodium were 

estimated by multiplying the calculated fluxes specified for each 

of the climatic/vegetation areas by the appropriate elemental 

mass fraction of soil. 

Road Dust and Field Tillage Emissioru 

71 

Road dust emissions were evaluated by cooperative work by 

the Illinois State Water Survey; results were described by 

Gillette et al. [1990]. Mass fluxes from tillage were quoted 

from the work of Evans and Cooper [1980]. 

9.1.3. RESULTS 

Mass production for suspended dust mass and the four 

alkaline elements Ca, Mg, K, and N a were summed for the 

contiguous United States. The results are shown in Table 9.1. 

The total mass of suspended dust of about 18.9 x 1 ()6 tonnes yr'! 

is small compared with D'Almeida's [1986] estimate for 

Saharan wind erosion aerosol production of (630-710) x IQ6 

tonnes yr!. On an equivalent mass basis, clearly the most 

important alkaline element is calcium, which contributes 62.1 % 

of the aunospheric aerosol alkalinity of the above four clements. 

Mg is second in contributions with 21.7% of the aerosol 

alkalinity. 

Table 9.2 gives the percentages of alkaline aerosol fluxes for 

each of the four principal sources of suspended dust production. 

The largest producer of suspended dust mass is the wind action 
Table 9.1. Total Mass Production Per Year, Total Equivalent 

Mass Production Per Year, and Percentage of the Combined 

Total Equivalent Mass Production for Four Alkaline 

Elements for Combined Road, Dust Devil, 

Wind Erosion, and Tillage Sources 

Ca Mg K Na 

Mass· (1Q6 T yrl ) 1.16 0.25 0.31 0.17 

Equivalent mass 0.058 0.02 0.0079 0.0072 

(IO' eq. T yrl) 

Percentage of 62.1 21.7 8.5 7.7 

combined total 

equivalent mass 

·Total mass production was 18.9 xl012 gyrI. 

Table 9.2. Percentages of Four Alkaline Elements and Total 

Aerosol Flux for Road Dust, Dust Devil, 

Wind Erosion, and Tillage 

Ca Mg K Na Total Mass 

(%) ('!o) (%) (%) (%) 

Road dust 68.8 61.7 29.0 25.6 40.3 

Dust devils 12.7 14.9 21.6 26.3 36.7 

Wind erosion 17.0 21.1 47.1 40.5 19.1 

Tillage 1.4 2.4 2.4 7.6 3.9 

upon soils (55%). "Wind action" (dust devils plus wind erosion) 

is dominant mostly in the western United States excluding the 

nondesert part of California and much of the mountainous 

regions. "Open anthropogenic" (road dust plus tillage) sources 

account for 44% of the dust produced in the United States and 

are dominant east of 95"W longitude. 

Because Ca is the dominant alkaline aerosol element, patterns 

of its emissions and deposition are representative of alkaline 

aerosols as a whole. For Ca, road dust is clearly dominant with 

almost 70% of total emission in the United States. The swn of 

aU the open sources for Ca are plotted in Figure 9.1. Ca 

emission has maxima in a large tongue originating at the Big 

Bend area of Texas; the Sonoran. Mojave, and Great Basin 

Deserts; a band of slates including Iowa. lllinois, Indiana, Ohio. 

and Permsylvania; and Massachusetts. 

9.1.4. COMPARISON WITH CALCIUM WET DEPOsmON DATA 

Wet deposition data (that is, dala from deposition collected in 

the wet deposition collectors) for the alkaline elements Ca, K, 

Mg, and Na from the NADP/NTN were made available to us by 

1. Gibson [personal communication, Ft. Collins, CO, 1988]. 

Wet deposition is only one pathway of atmospheric deposition. 

The other (dry deposition) is often thought to be of about equal 

effectiveness over a continental scale in removing particles from 

the atmosphere. Indeed, in dry regions as the southwestern 

United States, dry deposition is probably more effective in 

removing particles from the air because of the lack of rainfall. 

When comparing wet deposition data to calculated emission 

rates, solubility must be considered. Because dissolved material 

will be reduced by the ratio of soluble material to total material, 

the calculated alkaline fluxes should be reduced by a solubility 

factor depicting that part of the road material that can dissolve in 

the rain. This factor for Ca is 0.94 (calz el al. 1984). 

The wet deposition of Ca is shown in Figure 9.2. Total Ca 

emissions estimated in Figure 9.1 arc higher than wet deposition 

shown in Figure 9.2. For the arid regions along the southwestern border of the United States, this probably reOects the 

lack of rainfall. The large source area described as the old "dust 

bowl" (the panhandles of Texas and Oklahoma, western Kansas, 

eastern Colorado) typically produces much of its dust during 

winds from the southwest. Transport of this dust to the Midwest 

could explain the maximum of deposition starting in this area 

and slanting to the northeast. Road dust in Iowa and northern 

, " " " 

" 

" 

" 

" 

"'I. "'''''.Y')'' 1000 \0 0 0 _ 2.~ 

o 2.5 - 7.5 

o 1.5 ~ U.5 

G U.S ~ 25 

11/ 25-SO 

• >~ 

" " " " " " '" " .. " 

" 

" 

" 

" 

" 

" 

Fig.9.1. Annual emissions of ae rosol Ca. Units are equivalent grams 

per square meter per year times I (X)(). 

, " '" " " " " " " " " 

" " 

" " 

" " 

" " 

" " 

" " 

" eq. ~m .y,)" LCOO " 

0 0- 2.S 

" 2.5 - 1.S 

tJ 1.5 ~ U.S 

(!lU.5-25 

, , , '" " " " " " " 

Fig. 9.2. Wet deposilion of Ca detennined for NADP/NTN. Units are 

as in Figure 9.1. 

72 
Illinois may also explain the northern part of this maximum of 

Ca deposition. Large road dust Ca sources in Ohio, Pennsylvania, and Massachuseus are not reflected in corresponding 

large Ca deposition in those states. 

Emission estimates for the alkaline elements may be 

compared with the acid precursors sal and NO + N02 ([for 

example in the NAPAP preliminary inventory by Placet and 

Streets [1987]). In general, the picture formed of comparing the 

equivalent mass emissions divides the contiguous United States 

into an eastern portion (east of 95"W latitude), where emissions 

of alkaline materials are overwhelmed by emissions of acid 

precursors, and a western portion (west of 95"W latitude), where 

emissions of alkaline materials are only slightly smaller than 

emissions of acid precursors. 

This division is verified for the western United States by the 

Young et al. [1988] observation that 85% of the variance in 

sulfate is associated with variance of Ca, the dominant alkaline 

element found in our inventory. Another piece of evidence 

showing this division is a plot of the ratio of Cat(NO] + S04) in 

wet precipitation (where Ca., NO], and S04 are expressed as 

equiv.le",,) from July 5,1978, to February 4, 1986. The m.p 

(Figure 9.3) shows that for most of the western United States, 

except for the Pacific coastline, the ratio is greater than 0.3. 

9.1.5. CONCLUSIONS 

Total dust mass production for all open sources for the 

contiguous United States was used to generate emission rates 

and geographical patterns for alkaline emissions. Comparing 

the eSlimalcll sources of alkaline material given here with 

inventories of S02 and NO" (NO + NO~ by Placet and Streets 

[1987] gives the rough approximation that alkaline emission 

rates are only slightly less than the SOl + NO:.. emissions in the 

western United States bUI that !hey are much smaller than SOl + 

NO:.. in the eastern United States. 

Fig. 9.3. Ca/(NO] + S04) for wet deposition (%). Ca, 1\0], and S04 

were eJ:pressed in equivalents. Data are from the NADP for July 5, 

1978, to February 4,1986. 

9.2. ARCTIC GAS AJ'o:D AEROSOL SAMPlll\G 

PROGRAM: LrDAR DETECTION 

OF LEADS IN ARerlc SEA ICE 

R. C. SCHNELL 

9.2.1. Il\TRODUcnON 

Downward-viewing lidar data iliat were collected in !he 

Arctic winter by M.P. McCormick (NASA, Langley, personal 

communication, January 1984) were analyzed by AGASP 

scientists for the presence of haze layers. In some of the data, 

smoke-like plumes appeared to rise fTOm open leads in the ice 

surface to heights in excess of 4 km. A second airborne lidar 

was used in the Arctic on the AGASP [[ mission, March-April 

1986, to obtain additional information on these buoyant plumes. 

The overall results are presented here. 

73 

9.2.2. HYDRO~lETEOR PLUMES FROM OPEN LEADS 

A hydrometeor plume rising from an open lead, and a plume 

streamer from another lead are shown in Figure 9.4; data are 

from ilie lidar flown on the NASA Electra, at about 83 "-87"N, 

70·W, on January 27, 1984. The rising plume (Jcrl side of 

figure) has an ice source, about 300 k.m north of Ellesmere 

Island, and reaches nearly 4 km altitude. The streamer to the 

south comes from a wide lead off Ellesmere Island, which is off 

the figure, but was observed on the return night. This streamer 

extended downwind (northward) for about 250 km. The layer of 

aerosol observed at 3 km (1637 to 1650+ UTC) is Arctic haze 

air pullutioll. 

In April 1986, as part of AGASP [Schllell, 19881, a research 

aircraft operated by the Cloud and Aerosol Research Group of 

the University of Washington, equipped with cloud physics 

instrumentation and a I.06-~ downward-pointing lidar [Radke 

el aI., 1989], obtained cloud microphysical data over open leads 

in the Arctic. The lead-induced plumes were clearly associated 

with open-water regions. 

The lidar system was also able to identify newly frozen leads. 

A night made on April 18, 1986, off Baffin I,land, Can.da 

(Figure 9.5), shows both rcrrozen leads and a hydromeleor 

plume from an open lead. These lidar data were processed in a 

backscatter ratio color spectrum designed to highlight ice 

features. In Figure 9.5 the surface appears as a sharp boundary 

ncar the bottom edge; below the surface is a region of colors 

fading down the backscatter scale. Large areas with multiple 

leads, and single leads with dimensions grealer than !he 

horizontal resolution of the lidar (40 m) lack the gradual color 

gradient immediately "beneath" the surface. This gradient 

results from the following: when !he laser beam from lhe lidar 

strikes the highly renective snow surface, a strong return pulse 

saturates the receiver, which takes many nanoseconds to 

recover, thus producing a false signal below the surface. The 

less reflective surface of open and thinly covered leads produces 

no such saturation and lhus no false signal. The "below surface" 

signal should be interpreted as a measure of reflectivity, not of 

icc thickness. The locations and presence of the open and 

refrozen leads were conflTmed by photography and visual 

observations. 
Fig. 9.4. Backscauer signal from a O.6943-~ downward-viewing lidar flown on the NASA Electra north of Ellesmere Island, N.W.T., January 1984. 

White indicates maximum backscauer signal, decreasing linearly to black, which is indicative of scauering from gas molecules only. Shown are an 

apparent rising plume of hydrometeors (left) and a plume of aerosol (center and right) that had a surface origin at a ncar-shore lead 250 km to the sooth 

off of Alert, Ellesmere Island. The aerosol layer at 3 km is thought to be Arctic haze air pollutants. 

7 

.... 

Q) 6 

-.-. -

C\I en 

() - 5 en '2 

.::t. :::J E () >- C\I .... 4 0 CO C\I 

.... 0 

Q) 

- 10 

,~ :.0 3 

-.... C\I C\I 

--

~ Q) 

a: 

10 km 

Fig. 9.5. False-color imagery of the relative backscauer signal from the lidar operated on the University of Washington aircra(t. Colors indicate 

backscattering intensity from the lead·produced hydrometer plume and the ice surfaces. The signal is corrected and scaled to eliminate returns from gas 

molecules and aerosol particles. Lower backscatter beneath the ice surface indicates refrozen leads. 

74 
9.2.3. ROLE OF LEADS INll-lE ARcnc HEAT BUDGET 

Leads are of considerable interest to oceanographers and 

almospheric scientists. Much of the heat lost from the Arctic in 

winter is converted into ice in the leads; the resulting salt 

rejection and brine drainage fTOm the ice helps to maintain the 

Arctic Ocean halocline and may drive secondary circulations. 

Leads resull from ice deformation, prinlarily under wind 

forcing, and have typical widths of to-100m. Analyses of 

aircraft photographs, LANDSAT imagery, and submarine sonar 

data on under-ice draft show that the size distribution of leads in 

Arctic sea ice follows a negative power law such that aJong a 

lOO-kIn track one could expect to encounter 30 leads that are 50 

m wide but only 3 that are 500 m wide. During winter in the 

absence of ice deformation or movement of fraz.il ice by the 

wind, leads rapidly refreeze, forming new ice within a few hours 

[Badgley, 1966]. Although areas of open water and of new ice 

represent only a few percent of the ice-covered Arctic Ocean in 

winter, they have a major role in turbulent heat transfer to the 

aunosphere [Maykut, 1982J. Refrozen leads with ice 0.2·0.8 m 

thick may account for more than half of the turbulent energy 

transfer from the ocean to the almosphere in winter in the 

central Arctic [Badgley, 1966J. 

Previous field measurements [Andreas et aI., 1981] of the 

turbulent scalar fluxes over leads suggest that the heat and 

moisture transferred to the aunosphere remain within the 

atmospheric boundary layer because of the strong low-level 

temperature inversion that dominates the lower Arctic 

troposphere in winter. Our observations sh~w, however, that 

highly energetic plumes can penCLratc 10 an altitul1c of at least 4 

km. 

The upper-air sounding from Alert, Ellesmere Island, for 

1200 UTC January 27, 1984,5 hours before the observations in 

Figure 9.4, shows an inversion of 8"C between the surface and 

850 mb with an equivalent potential temperature (9c) at 4 km of 

O·C. Since €Ie is conservative for adiabatic processes, to 

penetrate the inversion and reach 4 km, a plume originating at 

the surface must be wanned and moistened there to a 8e of O·C. 

From the data, a CRREL scientist has calculated that the 

leads having plumes rising to 4 km must be roughly to k.m wide 

in order to wann and moisten the air flowing over it to a 8" of 

DoC. Realistically, however, this is the narrowest lead that could 

produce a plume that reaches 4 km for conditions in the Alert 

sounding. A plume will not rise adiabatically; through 

entrainment it will lose heat and moisture to the colder, drier 

ambient air. Therefore, to reach 4 km, the plume must have a 

surface ge value in excess of O°C; a more sophisticated plume 

model, however, is necessary to predict how much in excess of 

O"C €Ie must be. Although 10 similar major leads, estimated to 

be 5-10 km wide, are visible on Defense Meteorological 

Satellite Program infrared (2.7 km resolution) imagery along the 

night path for January 27, 1984, only 3 produced plumes; the 

others had evidently recently refrozen. 

9.2.4. SUM\fARY AND CO~CLUSIONS 

It is not surprising that structures as extensive as these 

plumes have not been recognized before. They are not 

necessarily visible to the naked eye. Also, previous research has 

focused on relatively narrow open-water areas [Badgley, 1966]. 

Further, our data suggest that small leads are lmable to wann 

and moisten the air enough to allow for vertical transport 

through a strong inversion. 

Our observations are significant for three reasons. First, 

airborne lidar provides a capability for locating narrow leads 

Ulat are smaller than the resolution of current satellite sensors. 

Recently refrozen leads are as easily detectable by lidar as the 

plumes from open leads. This capability is important for 

operational forecasting and for funer understanding of ice 

dynamics. Second, the current view that turbulent fluxes from 

leads and polynyas affect only the boundary layer needs 

modifying. If heat and moisture from leads can regularly reach 

the midLroposphere, the role of the Arctic as a global heat sink 

may need reevaluating and climate mode1s will require more 

realistic parameterizations of surface-atmosphere fluxes. Third, 

our results suggest that lead plumes may affect the radiation 

budget. Using observed ice crystal spectra, Curry et al. [19891 

calculated a significant healing effect at the surface, due to the 

downward infrared radiation from the ice crystals. Thus, 

plumes will affect the radiation budget in their immediate 

vicinity and in large areas downwind. 

9.2.5. Flil1JRE RESEARQ-I 

Airborne and satelliteborne lidar provide the potential for 

determining the impact of leads on the energy and moisture 

fluxes from the polar ocean to the atmosphere. Further research 

will focus on developing a climatology of lead occurrence and 

of plume frequency and distribution in the Arctic from lidar 

profiles and satellite data, identifying the phase of the plume 

moisture with lidar polarization measurements, and developing 

parameterizations to relate lidar backscatter to plume moisture 

content. 

9.3. REFERENCES 

75 

Andreas, E.L., R.M. Williams, and C.A., Paulson, Observations of 

condensate profl.les over Arctic leads with a hOl-film anemometer, 

Q.1. R. Meteorol. Soc. , 107, 431-460, 198 1. 

Badgley, F.l, Heat budget at the surface of lhe Arctic Ocean, Proceedings, Symposiwn on the Arctic J/eat Budget and Atmospheric 

Circulation, January 31-February 4, 1966, Lake Arrowhead, 

California, edited by 1.0. Fletcher, pp. 261-211, Rand Corporation, 

Santa Monica, CA, (NTIS: PB-182 433), 1966. 

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

C/imOlic CluJnge, No. 16: Summary Report 1987, 110 pp., NOAA 

Environmental Research Laboratories, Boulder, CO, 1988. 

Bocrngen, J.G., and H. T. Shackleue, Chemical analyses of soils and 

other surficial materials of the conterminous United States, Open 

File Report 81-197,139 pp., U.S. Geological Survey, Denver, CO, 

1981. 
Curry, I.A., EG. Meyer, L.F. Radke, c.A. Brock, and E.E. Ebert, 

Occurrence and characteristics of lower troposphere ice crystals in 

the Arctic, Symposiwn on the Role o/Clouds in Air Chemistry and 

Global Climate, pp. 114-117, American Meteorological Society, 

Boston, 1989. 

D' Almeida, G., A model for Saharan dust production, 1. Climate Appl. 

Mefeorol., 25, 903-916, 1986. 

Evans, 1.S., and D.W. Cooper, An inventory of particulate emissions 

from open sources, 1. Air Pol/W. Control Assoc., 30, 1298· 1303 , 

1980. 

Gatz, D.F., GJ. Stensland, M.V. Miller, and LC. Chu, Alkaline 

aerosols: An initial investigation of their role in delennining 

precipitation acidity, Final Report to NSF Grant ATM 77-24294, 

Report No. 343, 78 pp., Illinois State Water Survey, Champaign, IL, 

1984. 

Gatz, D.E, M.V. Miller, G.I. Stensland, and L.c. Chu, Evidence of 

element fractionation in ftne particle size classes of highly erodible 

soils, Proceedings 0/ the Specialty Conference on Particulate Maller 

Fugitive Dusts: MeasUl'emenJ and ConJrol in Western Arid Regions, 

Tucson, Arizona, OClObcr 1986, SlYS Reprint 820 , pp. 39-51, Air 

PoUution Control Association, Tucson, 1986. 

Gillette, D., and P. Sinclair, Estimation of suspension of alkaline 

material dust devils in the United States, Atmos. Environ., submitted, 

1990. 

Gillette, D., G. Stensland, A. Williams, W. Barnard, D. Gatz, P. Sinclair, 

and T. Iohnson, Emissions of alkaline elements, calcium, 

magnesium, potassium, and sodium from open sources in the 

contiguous United States, Global Bioch.em. Cycles, submitted, 1990. 

Maykut, G.A., Large scale heat exchange and ice production in the 

central Arctic, 1. Geophys. Res., 87 (CIO), 797 1-7984, 1982. 

Placet, M., and D.G. Streets, First interim assessment, National Acid 

Precipitation Assessment Program, Washington, DC, 1987. 

Radke, L.F, C.A. Brock, I.H. Lyons, P.V. Hobbs, and R.c. SchneU, 

Aerosol and lidar measurements of hazes in mid latitude and polar air 

ma sses, 1. A/mos. Chern., 9, in press, 1989. 

Schnell, R.C., Arctic air chemistry, Arctic Res., 2, 39-41, 1988. 

Sinclair, P.c., General characteristics of dust devils, 1. Appl. Meteorol., 

8. 32·45. 1969. 

Sinclair, P.c., Vertical transport of desert particulates by dust devils and 

clear thennals, Proceedings, Atmosphere-Sur/ace Exchange 0/ 

Particulates and Gaseous Pollutants, Energy Research and Development Center Series 38, 497-527, Richland, Washington, 1975. 

Sinclair, P.c., Dust devil dust transport features, 1. Appl. Meteorol., 

submitted, 1990. 

Snow D.IT, and T.M. McOelland, Dust devils at White Sands Missile 

Range, New Mexico, U.S.A. 1. Meteorol., 13, 157-164, 1988. 

76 

Young I.R., E. Ellis, an d G.M. Hidy, Deposition of airborne acidifiers in 

the western environment,i. Environ. Qual., 17, 1·28, 1988. 
10. Cooperative Programs 

Precipitation Chemistry 

R. S. ARrz 

NOAA, Air Rtsources LAboratory, Silver Spring. Maryland 20910 

1. INllWDUcnON 

Precipitation chemistry measurement programs continued at 

the 4 GMCC stations and at the 14 regional stations. Several 

changes were instituted to reduce costs and to improve quality 

controL A cooperative project, instituted through the University 

of Virginia. continued with liule change. 

2. BASELINE MEASUREMENTS 

Bimonthly chemistry measurements of snow samples 

continued nonnally at both BRW and SPO. At SMO collection 

of daily samples from the Acrochem Metrics sampler resumed 

and replaced funnel and bottle measurements at the conclusion 

of the drought. 

Sampling on the Island of Hawaii continued at Hila, 22 Mile 

Site, and at MLO. Suspected contamination from the funnel and 

bottle collectors was linked to the plastic tubing connecting 

several sections of the collector. Dry cieposilion is therefore no 

longer suspected as the primary cause of low pH values 

recorded at these stations. Preliminary results of a comparison 

betwecn MLO funnel and bottle. and University of Virginia 

Aerochem Metrics measurements suggests that SO; measure· 

ments are of very high quality but that pH values are suspect. 

150.00 ,----------- ---11----, 

-----

cr 

QJ 

:J 

"--"100.00 

Z 

o 

!;( 

tt: 

f-t3 50.00 

U 

Z 

o 

U 

0.00 

216---

,."~, •••••• ~:'" :' •••••• ,," ., •• ",w """""" , ••••••• 

N 

~ 

~ 

n 

~ 

~ 

Fig. la. Monthly volume·weighted SO;. NO). and H+ mean concentrations forMLO, 1980· 1988. 

77 

NO)" and Cl- measurements are also considered to be of high 

quality; however, the introduction of new Dionex columns 

should lower detection limits. 

3. NADP REGIONAL AND BASELINE M EASUREMENTS 

NADP measurements continued nonnally at MLO, SMO. 

and 12 regional stations. As a result of a statistical intercom· 

parison conducted for stations in Maine and Texas last year, the 

Presque Isle, Maine. and Victoria, Texas. stations were closed. 

A similar study is planned for FY 1989 for two stations in 

Mississippi; one station will be closed at the termination of this 

project. A third station at Salem, IlLinois, was closed in 

December 1988 when the NWS abandoncd the site; a replace. 

ment station has been proposed for a nearby location. 

4. MLOANDSMO 1980-1988CHEMlSTRYDATA 

Precipitation chemistry data from MLO and SMO are 

presented in Figures 1-4 for the period from May 1980 through 

1988. In Figures 1a and 1b, note that (unlike for regional sites) 

NO)" is proportionally very small relative to SO~ . Also note 

that SO~ and H+ (Figures la and Ib) Irack very closely. 

indicating that precipitation at both stations is primarily a very 

100.00 ,-------1\------ ----, 

60.00 

Z 60.00 

o 

f= 

<{ 

tt: 

I- 40.00 

Z 

W 

U 

Z o 20.00 

U 

0 .00 

o 

~ 

~ 

~ 

~ 

N n ~ ~ 

~ ~ 

- - 171 

~ 

~ 

~ 

Fig. lb. Monlhly volumc·wcighlcd SO;. NO). and H+ mean concentra· 

lions for SMO. 1980·1988. 
100.00 

~ 

"'- so· 

CT 80.00 H+' 

(lJ 

OJ ~ 

Z 60.00 

0 

i= « 

n:: 

f- 40.00 

Z 

W 

U 

Z 

0 20.00 

U 

.--, 0.00 

0 ;;; N n ~ ~ w ~ "' ~ 

"' "' "' "' "' ro ~ ~ ~ ~ ~ ~ ~ "' ~ "' ~ "' ~ 

Fig. 2. Monthly volume-weighted non·scasalt SO; mean concentra· 

tions and 1-1+ mean conccntralions for SMO, 1980-1988. 

~ 

"-

CT 

(lJ 

OJ ~ 

Z 

0 

i= « 

n:: 

fZ 

W 

U 

Z 

0 

U 

100,------------------------------, 

60 

60 

40 

20 

o 

ro "' 0> 0> 

No + 

CI 

N n 

"' "' 0> 0> 

.,. if) 

"' "' 0> 0> 

lD I""'- CO 0"1 CO co co CO en 0"1 0"1 rn 

Fig. 3D. Moothly volume-weighted Na+ and cr mean coocentrations 

forMLO. 

~,----------------------

Fig.4a. Monthly precipitation for MLO, 1980-1988. 

dilute solution of sulfuric acid. Figure 2 shows that monthly 

weighted non-seasall SO~ and H+ means concentrations for 

SMO during 1980-1988 do not track as consistently as those in 

Figure 1. Figures 3a and 3b indicate that although seawater is 

the predominant source of materi al to SMO rain, other factors. 

probably volcanic and typically small relative to regional 

stations. affect MLO precipitation. Figures 4a and 4b indicate 

that most cases with high ion concentrations (Figures l a and lb) 

can be quickly correlated with low amounts of precipitation. 

78 

"'-

CT 

2000,--------------------------------, 

Q) 1500 OJ ~ 

z 

o 

~ 1000 

n:: 

fz 

W 

U 500 Z 

o 

U 

Fig. 3b. Monthly volume-weighted Na+ and cr mean coocentrations 

forSMO . 

' 00 

" 

" 

" .. 

" " , 

~ " Po ., , 

" 

" 

Fig.4b. Monthly prec ipitation for SMO, 1980-1988. 
The Mauna Loa Aerosol Backscatter Intercomparison Experiment (MABIE) 

DAVIDA. BOWDLE 

University 0/ Alabama inllWllsville. Johnson Research Center, l-Iufltsvifle. Alabama 35899 

MADISON J. POST AND R. MICHAEL HARDESTY 

NOAA, Wa ve Propagation Laboratory. Boulder, Colorado 80303 

ANTONY D. CLARKE 

........... University oJ /lawaii, /-Iawaii InsliluJe a/Geophysics. Honolulu 96822 

EDWARDM. PATrERSON 

Georgia Institute a/Technology, School a/Geophysical Science. AI/onto. Georgia 30332 

1. Il\'TRODUC1l0N 

The Fall 1988 MABIE-FALL was conducted at MLO 

November 14-Deccmber 12, 1988. MABIE-FALL involved 

intercomparisons of direct measurements of aerosol optical 

properties at visible and mid-infrared wavelengths, and Mic 

theory estimates of these properties derived fTom collocated 

measurements of aerosol physicochemical properties. 

MABIE results are being used in the development of a 

global-scale model of aerosol backscauer properties for NASA's 

GLOBE [Bowdle, 1986J. GLOBE model results, in tum, arc 

being used in the design of NASA's LAWS [Curran, 1987]. 

LAWS is intended to provide three-dimensional fields of 

horizontal vector winds on a global scale in the troposphere and 

lower stratosphere beginning in the late 1990s. LAWS 

measurement accuracy will be critically dependent on the 

typical magnitudes and variability of atmospheric aerosol 

backscalter coefficients at the LAWS operating wavelength 

rHuffaker et at., 1984]. However, these aerosol parameters are 

currently not well characterized on a global scale, particularly in 

the middle and upper tr0IX>sphere over the remote tropical 

occans, where new wind measurements from LAWS are needed 

most. 

MABIE-FALL is one of several GLOBE field programs 

designed to provide the necessary aerosol information in these 

data-sparse regions. MABIE-FALL operations were the most 

recent in a series of seasonally distributed MABIE programs 

(MABIE-SUMMER in 1986 [Bowdle el al., 1987J, MABIEWINTER in 1988 [Clarke, 1988J, MABIE-FALL-Il in 1989, 

and MABIE-SPRING in 1990). MABIE-FALL was designed to 

(1) provide timely inputs on Pacific free-tropospheric aerosol 

properties to the incipient LAWS design effort, (2) evaluate 

instrumentation, sampling protocols, and analyticaJ procedures 

for the Fall 1989 GLOBE Pacific Backscatter survey night, (3) 

develop an internally consistent backscatter measurement and 

modeling data set, and (4) empirically link the MLO aerosol 

climatology to the GLOBE CO2 backscatter cJimatologies. The 

instrumentation, experiment design, and some preliminary 

results for MABIE-FALL are described here. 

79 

2. L'lSTRUMENTATION 

MABIE investigators provided three primary aerosol sensors. 

A ttailer-mounted, hemispherically scanned, pulsed CO2 

Doppler !idar [Post et at., 1989] was located north-northeast of 

MLO beside the MLO access road at 3.23 km altitude, with a 

3.0 km c1ear-line-of-sight slant range to the MLO site at 3.4 km 

altitude. This lidar provided range-resolved measurements of 

radial wind velocity or of aerosol backscatter coefficient at 9.25 

or 10.59 ~1 wavelength, every 300 m along the lidar line of 

sight. A modified high-resolution LOre lLAS -X, Particle 

Measuring Systems, Boulder, Colorado} and CNC [Model 3760. 

111crmoSystcms, Inc., Minneapolis, Minnesota}, with 

computer-controlled sample preheating (Clarke, 1988J, were 

located in a small shed -50 m west of the main MLO instmment 

building. These instruments drew from a PVC sample stack 

with inside diameter of to em and with sample inlet 8 m above 

ground (6.5 m above the roof of the shed). The LOPC provided 

size-segregated aerosol composition data, from direct measurements of aerosol size distributions as a function of prehealer 

temperature, and an a priori knowledge of the volatility 

characteristics of typical M LO aerosols. A high-volume 

filter/impac tor sampler in the shed drew out of the same sample 

stack. This unit provided bulk aerosol samples for conventional 

chemical analysis, and discrete particle samples for morphological and elemental analysis in an elecLIon microscope. 

Also available during MABIE were real-time outputs and 

daily sununaries from the standard MLO multi wavelength 

integrating nephelometer, CNC, and surface meteorological 

observations [Bodhaine and Rosson. 1988]. These products 

were used to evaluate ongoing experimental operations and to 

provide supporting data for (he aerosol measurement and 

modeling intercomparisons. Rawinsonde soundings for Hilo, 

Hawaii, -50 km northeast of MLO, were obtained from the Hilo 

NWS office. Local and regional weather forecasts and 

hard.copy satellite imagery were obtained from t.he Honolulu 

NWS. Digital satellite imagery was collected during MABIE on 

the NASA Marshall Space Flight Center MclDAS . Isobaric and 

isentropic back trajectories fTom MLO were provided by 
NOANGMCC. These local and regional meteorological data 

were used for long-range operational planning or for postexperiment analysis of air mass source conditions. 

3. EXPERillENT 

MLO was selected for the operational site to allow for 

sampling of undisturbed, marine, free-tropospheric aerosols for 

extended periods, without the problems of airborne operation. 

and to take advantage of the long-tenn MLO aerosol climatology [Bodhaine and Rosson. 1988]. The well-known nocturnal 

downslope flow at MLO [Bodhaine, 1983] facilitates such 

sampling for aspirated sensors. TIle high altitude of the site 

improves the CO2 lidar sensitivity in the middle and upper 

troposphere by reducing range-squared losses and water vapor 

absorption losses. Late fall was chosen for the operational 

period. to extend the seasonal coverage of the overall MABLE 

program. to increase the chances of encountering shallow 

marine boundary layers and very low free-tropospheric aerosol 

concentrations. and to provide timely input to the GLOBE/ 

LAWS studies. 

MABIE operations concentrated on intercomparisons of 

measured and modeled aerosol optical properties in nocturnal 

downslope flow conditions. Routine intercomparison studies 

involving the core MABIE instruments were nonnally 

scheduled every second night, weather pcnnilling, from -0600 

to 1800 UTC. During typical intercomparisons, the LOPC and 

the filter/impactor sampled continuously for 1-3 hours, while the 

CO2 Iidar was pointed several meters aoove the MABIE sample 

stack and pulsed at 2 Hz. Considerable care was taken to ensure 

the validity of the intercomparisons. First, return signals from 

the well-collimated beam of the scanning C02 lidar were used in 

conjunction with a rore-sighted telescope to map out "ground 

clutter." such as terrain. buildings. towers, and guy wires, in the 

vicinity of the MABlE and MLO sample stacks. Scrupulous 

care was taken to avoid these easily identifiable obstacles in 

subsequent lidar sampling. Second. the lidar was used in a 

scanning mode to verify the unifonnity of the aerosol population 

in the immediate vicinity of the MABIE sample stack. and also 

between the MABIE stack and the main MLO sample stack. 

Finally, intercomparison runs were terminated if cloud or fog 

developed in the vicinity. or if other meteorological, trace gas, 

or aerosol indicators began to vary rapidly. 

Several other types of experiments were aJso perfonned 

during MABIE. The LOPC frequcnlly operated continuously in 

an autonomous 3-h balch sampling mode for extended periods. 

The CO2 lidar obtained vertical, off-zenith, and low-angle 

backscatter profiles; off-zenith cirrus backscalter time series; 

high-resolution wind profiles in upslope, downslope, and 

transitionaJ now conditions; and intercom pari son runs with the 

MLO ruby lidar and with various satellite-based aerosol sensors. 

4. RESULTS 

Initial processing has been completed on most of the MABIE 

data. Three types of preliminary results are discussed here: (1) 

CO2 backscatter statistics, (2) comparisons between measured 

80 

and modeled aerosol optical properties, and (3) a 4-day dust 

plume event. 

More than 250 vertical profiles of aerosol backscatter 

coefficients at 1O.6-).ln1 or 9.25 ).ln1 wavelength were obtained 

during MABIE. Comparisons of vertical and off-vertical 

profiles generally gave internally consistent results. Composites 

of sequentiaJ sets of vertical, off-vertical, and low-angle profiles 

general1y showed (1) backscatter values of -3-5 x 10.11 m· 1 sri 

near the 3.4-km MLO altitude, (2) steadily smaller values above 

MLO until abou16-km altitude, (3) fairly unifonn values at -1 x 

10.11 m·t sri above 6 km, (4) slightly higher clear-air backscatter values arove 10 km (these data should be interpreted 

cautiously, since they were near the lidar sensitivity limit for the 

longer ranges), and (5) more frequent visible and subvisible 

cirrus above 10 km. MinimaJ wavelength dependence was 

observed between backscatter values at 9.25- and 1O.6-).ln1 

wavelength. 

Under well-established downslope now conditions, aerosol 

measurements at MLO should be representative of conditions 

ncar the Mauna Loa summit at -4.5-km altitude. At this 

altitude, typical aerosol backscatter coefficients at 1O.6-).ln1 

wavelength were -24 x 10.11 mol sri. Backscatter computations using Mie scattering theory with typical downslope 

WPC data from MABIE generally give vaJues about a factor of 

2-3 higher than the direct measurements. Under these same 

conditions, typicaJ nephelometer measurements gave aerosol 

scattering coefficients of -24 x 10-7 m-I at 0.55-).ln1 wavelength. 

The resultant conversion factor of -1 x 104 sri is generally 

consistent with theoretical predictions from aerosol data in other 

remole Tegions. Refinement .. of these geneTally encouraging. 

but not conclusive, results should be available from the 

complete results of the lidar and stack intercomparisons. 

An unusual aerosol plume was detected by the CO2 tidar at 

-2200 UTC November 30 and unambiguously detected by the 

MABIE and MLO surface samplers in downslope flow 

conditions at - 1200 UTC on December 2. All traces of the 

plume disappeared by ...()400 UTe December 4. During this 

event, lidar data showed spatia1ly and temporaJly coherent 

backscatter enhancements up to at least 6-km and possibly 8-km 

altitude for several days (Figure 1). Filter samples showed a 

dust-like coloration. LOPC data showed a refractory component 

(at 3OO'C) in the size distribution between 5- and 1O-).ln1 

diameter. Integrating nephelometer data showed minimal 

wavelength dependence in the aerosol scattering coefficient. 

Visual observations in all quadrants showed a dense whitish 

haze that filled the valley below MLO and extended well above 

MLO. Hilo rawinsonde profiles showed a deep dry layer 

encompassing the plwne altitudes. Isobaric back trajectories at 

700 and 500 mb showed 10-day origins near eastern China. 

Isentropic back trajectories tenninating near 700 and 500 mb 

showed similar origins. Surface observations in the China 

desert showed a major event of blowing dust approximately 10 

days before the plume was detected at MLO. Pulsed lidar 

observations in Japan showed a significant backscatter 

enhancement at about the time the China dust plume should 

have crossed Japan. These observations, taken together, point to 

an event of long-distance transport of super-micrometer-sized 
N . 

No LI ~- ;---""CI~O~'''''~--I~O~~''"'--~~I~O~-';----~~I-"O ' 

IJACKSC ,\TTER COEFFICIENT (m- I >1-- 1) 

Fig. 1. Vertical proriles of aerosol backscatter at 10.6 ~ wavelength 

obtained with a pulsed CO2 Doppler Iidar at MLO at 1506 UTC, 

December 2, 1988, during an event of long-distance mineral dust 

transport (squares) and at 0420 UTC, December 4, 1988, after the dust 

event (circles). 

mineral dust particles from the China desert to the centralPacific. Similar events in this region have been well documented, especially during the northern hemisphere spring. The 

MABIE event is remarkable, since it is the first such event in the 

1;~nu-a l Pacific region to be investigated with a pulsed Ii dar, and 

since it documents the presence of mineral dust at altitudes well 

81 

above 6 lan, even after several days and several thousand 

kilometers of transport over the Pacific Ocean. 

REFERENCES 

Bodhaine, B.A., Aerosol measurements at four background sites, 1. 

Geophys. Res., 88,10753- 10768, 1983. 

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

Climatic Change, No. 16: SummlJry Report 1987, pp. 3-29, NOAA 

Environmental Research Laboratories, Boulder, CO, 1988. 

Bowdle, D.A., A global-scale model of aerosol backscatter at CO2 

wavelengths for satellite-based lidar sensors, in Preprint Volwne. 

Second Conference on Satellite MeteorologylRemote Sensing and 

Applications, May 13-16, 1986, Williamsburg, VA, pp. 303-306, 

American Meteorological Society, Boston, MA, 1986. 

Bowdle, D.A., W.D. Jones, A.D. Oari<e, S.A. Johnson, and D.E. 

Fitzjarrald, Mauna Loa Aerosol Backscauer lntercomparison 

Experiment (MABIE), in Geophysical Monitoring for Climatic 

Change, No. 15: Summary Report 1986, edited by R.C. Schnell and 

R.M. Rosson, pp. 137-139, NOAA Environmental Research 

Laboratories, Bou]der, CO, 1987. 

Oarke, A.D., Some characteristics of aerosol size distributions at MLO, 

in Geophysical Monitoring for Climatic Clwnge, No. 16: SW11111ary 

Report 1987, edited by B.A. Bodhaine and R.M. Rosson, pp. 87-89, 

NOAA Environmental Research Laboratories, Boulder, CO, \988. 

Curran, R.J. (Ed.), Laws: Laser Atmospheric Wind Sounder, Earth 

Observing System Instrument Panel Report, Volwne IIg, 55 pp., 

National Aeronautics and Space Administration, Washington, DC, 

1987_ 

Huffaker, R.M., T.R. Lawrence, M.J. Post, J.T. Priestley, F.F. Hall, Jr., 

R.A. Richter, and RJ. Keeler, Feasibility studies for a global wind 

measuring satellite system (Windsat): Analysis of simulated 

performance, Appl. Opt., 23, 2523-2536, 1984. 

Pust, M.J., R.E. Cupp, and R.M. Hardesty, NOAA's pulsed Doppler 

tidar: Perfonnance characteristics, Appl. Opt., accepted, 1989. 
Fine Particulate Matter at Mauna Loa Observatory March 1988 to February 1989 

T. A . CAHILL. L. K. WILKINSON. P. BEVEREDGE. AND T. TANADA 

University o/California, Davis, Crocker Nuclear Laboratory, Air Quality Group, Davis, California 95616 

On March 2, 1988, the U.S. rcmotc-area fine particulate 

network IMPROVE [Eldred el at., 1989] initiated routine 

monitoring of fine (Dp < 2.5 ~) particulate matter at MLO. 

The IMPROVE protocols allow for a complete resolution of fine 

mass into its components for the purpose of predicting the 

effects of aerosols on the scattering and absorption of light, and 

the implications for visibility and the atmospheric radiation 

balance. Another IMPROVE station was initiated at about the 

same time at Hawaii Vo1canoes National Park. 

The protocols for MLO call for a continuous sample of 

approximately 3 days duration and a clean-air (downslope only) 

sample over lhe same 3-day period keyed by the Maryland 

System (W. Zoller et al.. personal communication). Size 

segregation is accomplished through a nominally 2.5-J.lffi 

cyclone (modified by altitude). and samples are collected on 

25-mm stretched Teflon filters. Samples are mailed weekly to 

Davis. where analyses are done for (1) mass (gravimetric); (2) 

elememal eomem, Na to U (PIX E); (3) (PES A); and (4) H, Be, 

B, C, N, 0, and Na (FAST) [Cahill et 01., 1984]. Data are 

provided in quarterly summaries. but neither all the analyses nor 

!.he MLO data protocols were completed at the time of this 

writing. Some results are presented here. 

Figure 1 shows fine particulate mass from March 1988 to 

February 1989 for MLOI (the continuous or average sample) 

and ML02 (the downslope only). The two mass components 

were only weakly correlated (Figure 2). Fine mass is dominated 

by soil dust in April and May, and by sulfur (sulfates?) during 

much of the rest of the year (Figures 3 and 4). 

Oceanic influences are easily seen by the presence of CI with 

Na. but in the past 9 months only a few days showed oceanic 

< 

• J .• 

J 

~ 

, 

.., 

o. 

o 

STUOT OA TE.!. MAR~H 

, '. 

, 

" 

• 

~ 

~ 

~ 

ti 

,--

'j : .~ , , 

, , 

I : 

, 

, , 

~ 

0 .' 

0., 

" 0.' 

0 . < 

o. ~ 

c.: 

" ,. , 

, , 

,;. 

a 

a o~o C 0 

/~'i.°Oo 'j'c 0 0 

0 ~ " 

a a 0 a 

00 

a 

V!:P4GE Fill;:: I.l:':;;'. :; '!!!'_:;: : !I !' 

o 1..I1t: P.OOR"'I.IS ·1.I3 

Fig. 2. Correlation between the two fine particulate masses (j.J.g m·3) 

March 1988-February 1989 of the clear sector (ML02) versus the 

average (MLOl). The typical uncertainty is shown. 

influence in the average samples. and none for the clean-air 

samples. These data generally conftrm and extend our earlier 

work [Wang el aL, 1982; Cahill and Braaten, 1983; Braaten 

and Cahill. 1986], although the spring S levels are higher than 

in earlier years. Full resolution of mass into elemental 

components will be attempted when the very-light-element 

analyses are completed. 

In May and early June 1988, a detailed study was made of 

aerosols from the eruption of Kilau~a at sites near the surface 

outbreak of lava very near the coast (VENT) and in the (now 

rUlE ,AA53 . CLUII SE·:TCR 

b 

0 .• 

6-M.-t> o 2 2J ::0 :1 II 2 2J lJ ] ::.1. I~ ~ "2': 17 1.1. '" :~ 

STUOT OATE:. IAAPCH 1966 - F"EB . 1ge9 

Fig. I. Fine particulate mass (}.lg m3) for (a) MLOI (the continuous or average samples) and (b) ML02 (the downslope only or clean samples). 

March 1983-February 1989. 

82 
'00,-----------------------------------------, 1:0 

• "0 ", 100 

' 00 90 

'0 

JOO '0 

'0 

'00 '0 

' 0 "'0 JO 

100 '0 

'0 10 

o 0 , , , a II 9 10 I I 11 1:: 

STUDY CA.T!; MAPCH,19!11! - fE!!P.U.I."'Y. I989 STUt'Y OUE: lAARCH,Iges - fEBPU;'RY, 19l!9 

Fig. 3. Conccnlration (ng m'l) of silicon (soil du st) in the fine mass for lhe (a) average samples and the (b) clean samples, March 198B-February 1989. 

.. ~----------~ 

0 .' 

0.' 

0 .7 

0 .' 

0 .' 

0 .' 

O.J 

0.: 

0 .' 

o 

SWOY O.TE: lAARt::H .1geS - FEBPUMtf. 1ge9 ~ IAICROORAt.A5 / 1.u 

,~-------------. 

0.9 

0 .' 

0.1 

0.' 

0.' 

0 .' 

' .J 

0 .: 

0 .1 

o <fo-t'LIl-t>, 

J 

b 

, , , . 10 11 II 1:: 

Fig. 4. Concentration ij,lg m3) of sullur in the finc mass for Ihe (a) average samples and the (b) clean samples, March 1988-February 1989. 

~~----------------------------

I"'" 51"'" 5111"1 .'25'" ""'1 III'" "'111' 

. -

.-.-~ ,~ 

0'-

Fig. 5. Concentration (ng m'l) of fine mass by site and dale, May 

4·Junc 16, 1988. 

83 

-

lUll. $1"'" ""'" 512"" 111,.. Ilt/" ",,, •• 

.-.-.-s v_ 0'_ 

Fig. 6. Concenlration (ng mol) of fine particulate sulfur by site and 

date, May 4-Junc 16, 1988. 
TABLE 1. Aerosol Composition (ng mol), Hawaii, May 1988 

Oceanic, 

Smoke, Volcan ic, 

Oceanic & Soil Soil Anthro. Trace Elements 

Location N. 0 Mg K Al Si C. Ti Mn Fe S, S V Ni Zn B, So Hg Pb' 

Upwind 

Hila (east coast) 86 196 24 32 5 1 109 29 4 1.8 3 1 • 317 7. 1 3.4 1.8 2.0 0.4 <0.1 3.8 

Near-Source 

End, Lava Tube , 5660 6420 970 266 26 120 122 3 6.1 38 2.3 1507 3.6 3.8 9.4 6.6 2.4 3.2 8.3 

at ocean 

Wahaula 2020 2840 420 133 52 III 60 6 5.9 24 4.3 1234 6.5 2.8 7.5 3.7 3.0 2.4 • 

(about 1 km)t 

Kealakomo 69 238 45 30 109 127 18 19 2.6 28 • 52 1 5.5 4.0 2.8 1.9 6.3 4.9 7.9 

(about 5 km) 

Downwind 

Hawaii Volcanoes • • • 37 26 70 33 2.5 • 23 • 63 1 • • 1.8 1.7 4.4 3.9 

National Park 

Honaunau 66 • 9 38 32 76 16 • 1.4 II 0.5 1872 1.2 1.0 1.0 1.9 0.9 0.9 5.3 

(Kana Coast) 

MLO • • • 40 78 227 84 5 0.9 52 • 438 <0.2 50.05 0.4 0.3 5:0.2 • 0.4 

U.S. Comparison Site (May 1988) 

Crater Lake • • • 27 55 99 24 3 • 32 • 104 • • 1.9 1.7 0.5 • 1.7 

National Park 

Shenandoah • • • 43 90 17 1 36 4 • 47 • 1805 • 8.3 3.3 l.l • 6.2 

National Park 

·Not enough data to form an average . 

tAl levels below 2 ng m3• Pb and As are not always distinguishable; if As, divide Pb by 3. 

* Deslroyed by lava, spring 1989. 

burned) Wahaula Visitor Center, at a site down lhe coast a few 

miles (Kealakomo), at Hila , and at Honaunau on the Kana Coast 

lTanada eI al., 1988; Gjll et al., 1989]. Figures 5 and 6 show 

the results of sampling between May 4, 1988, and June 1, 1988, 

for fine mass and S, and Table 1 shows mean elemental 

concentration at all sites. Surprisingly, but in confonnance with 

qua1 itative local observations, fine particulate S often reached its 

highest levels on the Kona Coast (Figure 6). This might 

possibly be explained by the time delay between S02 emission 

at the cone and lava tubes and conversion into sulfates in the 

presence of sunlight and water. Lack of ammonia might favor 

an H2S0 4 acidic aerosoL There is a large pool of fine sulfate 

aerosols ringing the MLO that may account for some of the S 

values on upslope winds. 

Aclcn.owfedgmenls. The authors gratefully acknowledge the 

excellent cooperation shown to us at MLO during the past year, as 

exemplified by an extremely high rate of valid samples retumed over the 

last three quarters. We also wish to acknowledge the enthusiastic 

support for this program by William Malm, :r-.,rpS, Ft. Collins, Colorado. 

REFERENCES 

Braaten, D.A., and T.A. Cahill, Size and composition of Asian dust 

transported to Hawaii, AfnwS. Envron., 20, 1105-1109, 1986. 

84 

Cahill, T.A. , and D.A. Braaten, Size characteristics of Asian dust 

sampled at Mauna Loa Observatory, in Geophysical Monitoring for 

Climiltic Change, No. J/: Swnmary Report 1982, edited by 1.M. 

Harris and B.A. Bodhaine, 117-119, NOAA Air Resources 

Laboratory, Boulder, CO, 1983. 

Cahill, T.A., R.A. Eldred, D. Shadoan , P.l. Feeney, B.H. Kusko, and T. 

Matsuda , Complete elemental analysis of ae rosols: PIXE, FAST, 

LIPM, and mass,Nuci./nslrum. Methods, B3. 291-295,1984. 

Eld red, R.A., TA. Cahill , L.K. Wilkinson, PJ. Feeney, and W. Maim , 

Particulate characterization at remote sites across the US: First yea r 

results of Ihe NPS/IMPROVE Network 89-15 1.3, Proc. of Annual 

Meeting, Air and Waste Management AssociLltion, Anaheim, CA, 

89-151.3 ,1989. 

Gill, T.E., T.N. Tanada, TA. Cahill, D. Taylor, and H. Matsuura , Air 

quality on Hawaii island during a Kilauea eruption. Proc. oj Annual 

Meeting, Air and Waste Management AssociLlljon, Anaheim, CA, 

89·66A.4, 1989. 

Tanada, T.N., T.E. Gill, T.A. Cahill, and K.l. Bowers, The Hawaii '88 

aerosol monitoring project, Report to National Park Service and 

State of Hawaii, Public Health, University o f California, Davis, 

Crocker Nuclear Laboratory, 1988. 

Wang, M. , T.W. Winchester, T.A. Cahill, and R. Luin, Chemica l 

elemental composition of wind-blown dust, April 19, 1980, Beijing, 

Dexue Tongbao (Science Bulletin). 27, 11 93- 11 99, 1982. 
Artificial Windshielding of Precipitation Gauges in the Arctic 

GEORGEP. CLAGETT 

Soil Conservation Service, Anchorage, AlaskLl 99501 

1. IN1RODUCIlON 

Precipitation gauges can give a good measure of the water 

equivalent of snow precipitation, provided the gauge is 

protected or shielded from wind effects [Brown and Peck, 

1962]. Unfortunately, there is little that is "standard" to the 

science of collecting snow precipitation. 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 con· 

ducled. A lingering question is whether the results can be 

appied to the local conditions of Alaska's tundra regions. 

2. ThE ?ROBLEl,1 

The gauge catch efficiency for snowfall is known to change 

with increasing wind speed in exposed areas [Bemon, 1982; 

Goodison, 1978]. At speeds of 5 m s-l (11 mph), unshielded 

gauge catches are known to drop to 20·30% of the true amount, 

and even as low as 6% for an entire winter of abnonnally windy 

conditions [Clagell, 1988J. One solution to the exposed gauge 

problem is to calibrate gauge catch efficiency with wind speeds 

and then record wind speeds at the gauge height in order to 

apply the correction. Another solution is to apply the "dual 

gauge" approach, that is, to use two adjacent gauges, one 

shielded and the other one unshielded, which provides a 

relationship with increasing wind speeds to calculate total solid 

precipitation [Hamon, 1973; Hanson, 1988]. Both of these 

solutions best fit individual sites, but are not generally practical 

for large networks. 

Artificial windshielding of the precipitation gauge is yet 

another option. Three artificial windshields have significant use 

in North America: (1) The Alter shield is known to increase the 

snowfall catch of an unshielded gauge by about 30% [Aller, 

1937; lVornick, 1953]. (2) The Nipher shield was developed by 

the Canadian government in the late 1970s and was subse· 

quently adopted as the Canadian national standard shield for 

precipitation gauges. It provides a snowfall catch thal is not 

significantly different from the total or "true" snowfall amount 

[Goodison et al., 1983]. The one-piece Nipher shield also is the 

most affordable of the various shield options. It costs one·half 

as much as an Alter shield, is easy to install, and is relatively 

maintenance free. Its on1y drawback is that it easily caps over 

during wind· free storms and may cap over if wind velocity is 

below 2 m S·I , Therefore, its use is limited to staffed locations. 

But at most sites, it is the most practical solution to the exposed 

precipitation gauge problem. (3) The Wyoming shield was 

85 

developed by the University of Wyoming in the early 1970s 

[Rechard and Larson. 1971]. Several studies found that it 

provides a snowfall catch that is about 85·95% of the total 

snowfall [Benson, 1982; Brown and Peck, 1962; Goodison, 

1975; Goodison et al., 1983; Rechord, 1975]; however, a U.S. 

Forest Service study found the gauge caught only 48% of that of 

a "control" gauge located in a forest opening {Stwges. 1984]. 

The drawbacks of a Wyoming shield are numerous. Its size·· 6 

m in diameter--is much larger than other shields, it costs five 

times as much as a Nipher shield, and it requires occasional 

maintenance. Its use is generally limited to unstaffed locations. 

Although the studies cited establish a relative catch efficiency 

for the various windshields, the range of variation is quite wide 

when the unshielded, Alter·shie1ded, Nipher-shielded, and 

Wyoming-shielded catches are related to each other. One 

reason for the variation is likely to be the wide range of wind 

and snow conditions under which the various studies were 

conducted. 

Another problem that further compounds the issue and that is 

not uncommon in Alaska's Arctic coastal region is rime 

accumulation. Rime is an opaque coating of ice particles caused 

by the freezing of supercooled water droplets or fog on impact 

with an object. including the ground or snow surface. NWS 

does not consider rime as true precipitation. Ground fog is a 

phenomenon that always occurs under clear skies. Conse· 

quently, with a frequent gauge.servicing interval, NWS is able 

to separate riming events from precipitation events and 

eliminate the accumulation of rime inside the orifice of a 

precipitation gauge from entering the record. Obviously, this is 

not always possible at unstaffed sites. Furthermore, whether or 

not to count rime as precipitation is a debatable issue; rime 

certain1y adds to the moisture reaching the ground. A compari. 

son of 12 years of dual records at BRW and Barter Island, 

Alaska, between unshielded and Wyoming·shiclded gauges 

indicates the Wyoming shield allows a snowfall catch slightly 

greater than 3 times the unshielded catch over the 9·month 

winter period (Clagett, 1988]. However, Wyoming gauges were 

never serviced more than twice monthly at BRW, and often not 

for several months in a row at Barter Island. Therefore, rime 

accumulation creates a potentially significant source of bias in 

that comparison. 

3. ThE SOLUTION 

A study of the windshield alternatives, at a staffed location, 

under the unique conditions of Alaska's Arctic coastal region. is 

vitally important for measuring accurate precipitation amounts. 

Results of the study will reflect on an expanded future network 

of shielded precipitation gauges on the North Slope, western, 

and southwestern tundra regions of Alaska. Most of these 

potentially new sites arc in rural villages, where they may be 

semi·staffed, but will need to operate independently for the most 
part. Will the Nipher shield operate under these conditions? 

What will be the comparison of the Nipher shield record against 

the longer-term records of unshielded and Wyoming shielded 

gauges? What is the significance of rime and its effect on the 

various windshields? A study to answer these questions will 

begin in August 1989 at BRW. 

The snowfall catch from five storage precipitation gauges 

will be compared the first year, wee shielded and two 

unshielded: (I) Wyoming shielded; (2) Nipher shi elded; (3) 

Alter-shielded; (4) unshielded and serviced on an event basis, 

the same as the wee shielded gauges; and (5) unshi elded but 

treated as if it were a remote gauge, allowing rime to build up 

and dissipate naturally to see what effects it has on the overall 

catch. All storage cylinders will be 20.3 cm diameter x 100 cm 

tall, mounted with the orifice 2 m above the normal ground 

surface. Recording precipitation gauges will replace the storage 

gauges the second year of operation. 

WMO began an international study of artificial windshielding 

in 1986 [Goodison e/ al., 1985]. Several additional shields in 

common usage in Europe and Russia will be evaluated 

simultaneously along with the other five, including the 

unshielded standard gauge of the United States. The BRW 

study will allow us to tie in the results from North Slopc's 

unique conditions with those from the broader WMO study 

being conducted in snowy regions around the world. 

REFERENCES 

Aller. S.c. , Shielded ~torage precipitation gages. Mon. W~athu Rev .. 

65,262·265, 1937. 

Benson, C.S., Reassessment of winter precipitation on Alaska's Arctic 

slope and measurement on the nux of wind blown snow, Report 

VAG R·288, 26 pp., Geophysical Institute, University of Alaska, 

Fairbanks, 1982. 

86 

Brown, MJ., and E.L. Peck, Reliability of precipitation measurements 

as related 10 exposure, J. App/. Meteorol., 1,203-207, 1962. 

Clagell, G.P., Snowfall measurements in the Arctic, Geophysical 

Monitoring for Climatic Change, No. 16: Summary Report 1987, 

edited by B.A. Bodhaine and R.M. Rosson, pp. 90-92, NOAA Air 

Resources Laboratory, Boulder, CO, 1988. 

Goodison, B.E., Snow studies at Cold Creek: Testing and evaluation of 

gages used in Canada for fresh snowfall measurement, Proc. 

Canadian Hydrology Symposiwn, 75, Winnipeg, National Research 

Council of Canada, Winnepeg, 26·35, 1975. 

Goodison, B.E., Accuracy of Canadian snow gauge measurements, J. 

Applied Meleoroi., 17(JO), 1542- 1548, 1978. 

Goodison, B.E., V.R. Turner, and J.E. Metcalfe, A nipher-type shield for 

recording precipitation gauges, 5th Symposium on Meteorological 

Observations and Instrwnentation, Toronto, Ontario, Canada, pp. 

21-26, American Metcorological Society, Boston, 1983. 

Goodison, B., B. Sevruk, B. Dahlslron, and S. Klemm, International 

Organizing Committee for WMO Solid PreCipitation Measurement 

Intercomparison, Nomoping, Sweden, December 16-20, 1985, Final 

Report, World Meteorological Organi7..8tion, Geneva, 1985. 

Hamon, W.R., Computin g actual precipitation, in DistribuJion of 

PrecipilOlion in MounJainous Areas, WMO No. 326,Vol. I, pp. 

159-174, World Meteorological Organization, Geneva, Switzerland , 

1973. 

Hanson, c.L., Precipitation measured by gages protccted by the 

Wyoming shield and the dual-gauge system, Proc. 56th Western 

Snow Confer~nce , Kalispcl1, Montana, pp. 174-177, Colorado State 

University, Fort Collins, 1988. 

Rechard, P.A., Measurement of winter precipitation in wind-swcpt 

areas, Proc. Snow Management of th~ Great Plains, Bismark, North 

Dakota, pp. 13-30, University of Nebraska. Lincoln, 1975. 

Rechard, P.A., and L.W. La rson, The use of snow fences for shielding 

precipitation gages, Proc. 39th Weslern Snow Conference , Billings, 

Montana, pp. 56-62, Colorado State University, Fort Collins, 197 1. 

Sturges, D.L., Comparison of precipitation as measured in gages 

protected by a modified Alter shield, Wyoming shield, and a stand of 

trees, Proc. 52nd W~ tern Snow Conference , Sun Valley, Idaho, pp. 

57-67, Colorado State University, Fort Collins, 1984. 

Warnick, C.c., Experiments with windshields for precipi18tion gages, 

Trans·Am. Geophys. Union, 34, 379-388,1953. 
UVB Monitoring Data from Mauna Loa and Rockville 

DAVID L. CORRELL, CARL CLARK, RUSSELL GOODRICH, AND DOUGLAS HAYES 

Smithsonian En vironmental Research Center, P.O. Box 28. Edgewater, Maryland 21037 

Our laboratory has lx!cn continuously monitoring surface 

irradiance in a series of eight 5-nm band passes in the UVB at 

various locations on the Earth's surface with high-precision, 

accurately calibrated, interference-filter spectral radiometers. 

Significant data sets have been collected at BRW (7 1-N); 

Rockville and Edgewater, Maryland (39'N); Tallahassee, 

Florida (30'N); MLO (I9'N); Republic of Panama (9'N); and 

spa (90·5). Long-tcnn data sets are now being edited and 

anaJyzcd for publication and archiving; these sets include data 

from 1976 10 the present at Rockville and from August 1984 to 

the prescnt at MLO. 

Data editing includes checking for file consistency; screening 

for data processing and file maintenance errors by testing for 

unreasonable ratios between channels, times of sunrise and 

sunsel, and effects of cloud cover; and correcting for calibration 

changes, and equipment malfunctioning. and altered equipment 

design. 

Data from Rockville from 1976 through 1988 have now been 

edited and arc archived on 9-track computer tapes. Extensive 

analyses of these data are in progress. and a few highlights are 

reported here. Requests for data or further infonnation should 

be directed to David L. Correll, Director, at the above address. 

A new-generation. 1 R-channel. interference-filter spectral 

radiometer is nearly ready for field operation. In the UVB it 

will have 2-nm band pass filters. This instrument features not 

only better spectral resolution and modem electronics. but also 

improved PC-based data acquisition and microprocessorcontrolled choices of set gains over 3 orders of magnitude for 

di fferent channels in the same operational instrument. Both the 

present radiometers and the radiometers under development 

operate as cosine collectors to measure global irradiance. We 

are currently surveying possible additional station sites in order 

to attain an optimal range of latirudes for future data collection. 

14 00 

1300 

:200 

1100 

1000 

'" ." " 700 

• .. , 

'" 

, 

, 

y 400 

3" 

......•. ~\ . 

.... } .. 

.... ' .. ··,.D .. 

"k::~~R 

J~n rEB MAR APR MAl JUN JUL Aut S(P OCT MOV OEC 

HOMIM 

Fig. 1. Daily total irndiance fluxes (J m-2 nm'! d ol at 300 nm). 

averaged by monlh. 

87 

Mean UV global irradiance in July at 39°N latitude were 76. 

583, and 2311 J m-' nnr' d-' at 300, 305, and 310 nrn, respectively in 1976. These fluxes increased to 211,1328. and 3676 in 

July 1983. UV radiation fluxes declined again in 1987 and 

1988. When measured total daily fluxes (averaged monthly) are 

compared with those predicted by the "Green" model [JohllSon 

el al., 1976], the higher fluxes, such as those measured in 1983. 

arc very similar (Figure 1)- Thus it is the attenuation of the 

short-wavelength part of the UVB regions in periods of low 

irradiance, such as in 1976 (Figure I), that is unexpectedly 

large. 

Morning. clear-day secant = 2.S fluxes had both annual and 

II·year variations for the short-wavelength end of the UVB 

specLral region. Annual minima usually occurred in May. 

having a long-tenn average of 2.98 and 114 mJ m-z run-I min at 

300 and 30S nrn, respectively. Annual maxima usually occurred 

in November and had a long-lenn average of 30.S and 282 mJ 

m-2 nmj min-! at 300 and 30S nm, respectively. Annual 

monlhly average minima for morning. clear-day. secant = 2.5 

fluxes at 30S nm (Figure 2) were lowest in 1978 (28_8 mJ m·2 

run min) and highest in 1985 (266 mJ m'z nm'! min-!)_ The 

annual monthly average maxima at 30S run were lowest in 1976 

(109 mJ moz run-I min'!) and highest in 1984 (S46 mJ m'z nm'! 

min'!). Thus, over a solar cycle annual minima al 305 nm 

varied ninefold. while maxima varied fivefold_ 

We believe that this large attenuation of the short-wavelength 

end of the UVB spectral irradiance during periods such as 

1976-1978 and 1987-1988 is a response to increased 0) 

concentrations in the stratosphere, which result from increased 

solar nare activity. Since almost all of the UVB global 

irradiance we measure is diffuse sky light [Dave and Furukawa, 

1966; Dave and Halpern, 1976J. the effective optical pathlength 

through the aunosphere is increased substantially over that of 

, 'I 

0.51 

, , \ 

I 0.31 

" I 

" I 

0.0 1 , 

" " " " .. " " 

Fig. 2. Monlhly averages for morning, c1ear-day, secam = 2.5 nuxes (J 

m-2 nm-I min-! al305 run). 
direct sunlight. Therefore, relatively small changes in 0 3 

concentration cause large fluctuations in UV irradiance on the 

Earth's surface at wavelengths strongly absorbed by 03. 

Certainly, the changes in global irradiance we are reporting are 

not due to significant changes in UVB radiation incident to the 

Earth's atmosphere [Lean, 1989 ]. 

REFERENCES 

Dave, l.V. , and P.M. Furukawa, Scattered radiation via the ozone 

absorption bands at selected levels of a Rayleigh atmosphere, 

MeleoroJ. Monogr .• 7, 353 pp., American Meteorological Society. 

Boston, 1966. 

88 

Dave, J.V., and P. Halpern, Effect of changes in ozone amount on the 

ultraviolet radiation received at sea level of a model atmosphere, 

Almos. Environ., 10, 547-555, 1976. 

Johnson, F.S., T. Mo, and A.E.S. Green, Average latitudinal variation in 

ultraviolet radiation at the earth's surface, Pholocliem. Phoiobio/., 

28, 179-188, 1976. 

Lean, J. Contribution of ultraviolet irradiance variations to changes in 

the sun's total irradiance, Science, 244,197-200,1 989. 
Status of the Robertson-Berger UVB Monitoring Program, 1974-Present 

GERALD F. COTIEN 

NOM , Air Resources LAbora/ory, Silver Spring, Maryland 20910 

1. I NTRODUCTION 

MLO has served as one of the original 10 monitoring sites 

for the Robertson-Berger (R-B) Sunburning Meter network 

since its inception in 1974. An additional 24 sites. plus 11 

non-U.S. sites, distributed unevenly worldwide, have operated 

with varying lengths of record. Until June 1989. the Skin and 

Cancer Hospital of Temple Universiry has maintained the 

network functions, principally with contract support variously 

over the years from NIH, DOT, and EPA, with extensive field 

support by NOANERL and NWS. The Skin and Cancer 

Hospital closed this year, so the operation of the network is 

currently being reviewed to determine whether measurements 

should be continued to overlap with measurements by more 

sophisticated inslrumentation. The National Cancer lnstitute of 

NIH retains the data archive along with ancillary meteorological 

information. 

2. INSTRUMENTATION AND DATA 

The R·B meter was selected in the early 1970s as a UVmonitoring instrument at the surface for the Climatic Impact 

Assessment Program [ClAP, 1975J sponsored by DOT in 

reac lion to concerns about possible climate impacts hy the 

projected supersonic air lransponation fleet. The instrument, 

described by Berger [1976], detects radiation in the UVB 

wavelength band, 295·330 nm. The meter response declines 

logarithmically such that the response at 330 nm is one-hudredth 

that at 295-300 nm. Although the R·B meter has a1ways been 

accompanied by controversy, especially with respectlO the wide 

UYB bandwidth and more recently with possible long-term 

instability (or drift) [ScollO el al., 1988], it has proved to be a 

rugged, reliable instrument in the field. The Temple University 

staff maintained individual instrument calibrations that were 

performed annually tJuough mid·1989 except for an unfunded 

period from mid·1983 to mid·1985. There were several 

comparisons of the R-B meter with more sophisticated 

instruments, obtaining side· by-side measurements over varying 

time periods [Mo el at., 1975; Machta el ai., 1976; Barlon, 

1983; Pal/ridge and Barton, 1978J. In addition, DeLujsj and 

lIarris [1983] performed an important though limited study of 

the meter behavior, providing under certain conditions estimates 

of the radiant energy of the somewhat arbitrary R·B sunburn 

unit of measurement. Finally, efforts have been made to modify 

the meter sensor in order to more nearly match the erythemal 

(McKinlay. Diffey action spectrum) response function. Berger 

[1989] prepared two "thin phosphor" instruments that were 

operated for approximately 1 year each at McMurdo and 

Temple Universil)'. These data are unavailable as of this 

writing. The published results of the CSIRO Austra1ian network 

(1975.1981) include both types of instrumentation [BarlOn, 

1983; Paltridge and Barton, 1978]. 

89 

The period of record for each R·B observing sites is given in 

Table 1 (1974.1987). listing the number of complete years for 

each location. The data are retained as half.hourly sunburn 

units, which are archived as well as daily and monthly totals, 

along with observed daily and monthly Dobson ozone, percent 

sunshine, tota1 cloudiness, and broad band solar radiation 

amounts where these are available. These data may be obtained 

from Joseph Scotto, NIH, National Cancer Institute, Public 

Health Service, Bethesda, MD 20892. 

TABLE l. Robertson·Berger Meter Network 

Stations 

Albuquerque, NMAllanta/Emory, GABismarck, ND 

Burlington, VTConcord, NHDes Moines, lA 

Detroit. WEI Paso, TXFl. Worth, TXGainesville, FL 

Honeybrook, PA 

La JoUa, CA 

Lihue, HIMauna Loa, InMiami, FLMinneapolis, MNNew Orleans, LAOaklandlRedwood City. CAPhiladelphia, PAPt. Barrow, AKRockville, MD 

Salt Lake City, UP 

Sealue, WATallahassee, FL 

Tucson, AZNo. of 

Complete 

Years 

United StaleS 

12 

7 

II 

2 

2 

9 

ID 

13 

14 

2 

10 

3 

D 

12 

O 

\3 

4 

12 

14 

8 

5 

9 

9 

12 

6 

Start 

Jan. 1974 

De,- 1977 

Jan. 1974 

Oct. 1985 

Oct. 1985 

Jan. 1974 

Sept. 1977 

Jan. 1974 

Jan. 1974 

Jan. 1975 

lon. 1975 

May 1979 

Feb. 1987 

Jan. 1974 

May 1986 

Jan. 1974 

Nov. 1977 

Jan. 1974 

Jan. 1974 

Oct. 1978 

Sept. 1978 

Oct. 1977 

Oct. 1977 

Jan. 1974 

Jan. 1980 

Non.United States 

Brisbane, Australia 7 Oct. 1974 

Melbourne, Australia II Dec. 1974 

Hamburg, Gennany 5 Feb. 1976 

Hamilton, New Zealand- 3 May 1980 

Invercargill. New Zealand 2 SeP'- 1981 

Barro Colorado, Panama- 3 Nov. 1978 

Belsk, Poland- II May 1975 

Warsaw, Poland I June 1975 

Norrkoping, Sweden- 4 Oct. 1982 

Basel, Switzcrland- 7 March 1980 

Davos, Switzerland- \3 Jan. 1975 

-Stations currenuy op:rational 

End 

Sept. 1987 

Feb. 1987 

Dec. 1987 

Aug. 1980 

July 1985 

March 1983 

July 1985 

May 1986 

Apr. 1981 

Nov. 1986 

June 1983 

Oct. 1985 

Sept. 1976 
REFERENCES 

Barton, 1.1., The Australian UV-B monitoring network, DiYision of 

Almosphuic Physics Technical Paper No. 46, eSIRO, Aspcndalc, 

Victoria, AustraHa, 1983. 

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

Photobiol .• 24, 587,1976. 

Berger, D. , Produ ct Brochure, Solar Light Co., Philadelphia, PA, 1989. 

ClAP (Climatic Impact Assessment Program), Impacts of Climatic 

Change on the Biosphere, Final Report, ClAP Monograph 5, 

DOT-TST·75·55. Department of Transportation, Washington, DC, 

1975. 

DeLuisi, 1., and J. Harris, A detcnnination of the absolute radiant energy 

of a Robertson-Berger Meter Sunburn Unit, Almos. Environ. 17(4), 

75 1·758, 1983. 

Machta , L, G. Cotton, W. Hass, and W. Komhyr. Erythemal ultraviolet 

solar radiation and environmental factors, Proc. of the Fourth 

Conference on the Qimalic Impact Assessment Program, 

DOT·TSC·Os[·75·38, 4()5·411, 1976. 

Mo, T., A.T. Chai, and A.E.S. Grecn, An absolute ca1ibration of the 

sunburn meter, in ImpaClS of Climalic Change on the Biosphere, 

ClAP Monograph 5, Appendix L, 2-241, Department of Transportation, , Washington, DC, 1915. 

Paltridge, G.W., and 1.1. Barton, Erythemal ultraviolet radiation 

distribution over Australia--Calculations, detailed results and input 

data, Division of Almospheric Physics Technical Paper No. 33 , 

CSIRO, Aspendale, Victoria, Australia, 1918. 

Scotto, J., G. Cotton, F. Urbach, D. Berger, and T. Fea rs, Biologically 

effective ultraviolet radiation: Surface measurements in the United 

States, 1914-1985, Science, 239, 762-764, 1988. 
The CSIRO Latitudinal Gradient Study of CO2 Isotopes 

ROGER FRANCEY. PAUL FRASER. AND GRAE.\1E PEARMAN 

CSfRO, Division of Atmospheric Research. Aspenda/e, Victoria, Australia 3/95 

1. Ir-."JRODUCTION 

For long-lived atmospheric trace gases, zonal mixing 

suggests that a small number of carefully selected clean-air sites 

spanning latitudes from the north to south poles can provide a 

global perspective on the budget of each species. The gases of 

interest in this study arc those influenced by human activity and 

implicated in environmenlal change by modification of Lhe 

radiation balance of lhe atmosphere; spccifical1y COz. CH4• CO, 

NzO, and some CFCs. The primary focus is on the stable 

isOlOpic composition of CO2, measured as ratios linC and 5180 

relative to the PDB (used here to describe reference CO2 

evolved from carbonate) standard. The sne ratios, where 

I umple . 

[ 

I3C/'2C J S 'C= '3C/'2 CPDB -I ,1000 (permd) (1) 

are thought to characterize nel atmosphere-surface exchanges 

involving the terrestrial biosphere (including biologically 

derived fossil fuel) and so can be used to distinguish COl from 

this source compared with that from an oceanic source [Keeling 

el al., 1980; Pearman and Hyson, 1986]. The lil8() ratios, where 

SI'O= [ 'SO/'·Oump" -IJ ,1000 (permi!) (2) "O/16 0 PDB 

in CO2 arc thought to involve gross CO2 exchange with land 

plants [Francey and Tans, 1987]; they provide potentially useful 

new information on large-scale biological responses and/or 

atmospheric lransJX'rt. Unlike other known global sampling 

networks, this network has the feature of pre-drying air. which 

may have implications for DC monitoring and is crucial for S18Q 

in COl' The establishment and operation of the sampling 

network arc described here. Brief reference is made to 

significant results emerging from analyses of the samples. 

2. NETWORK DESCRIPTION 

The CSIRO/DAR nelwork was eslablished at the end of 1983 

with funding support from NERODC and logistic support from 

NOANGMCC and CGBAPS. Monthly sample collections 

SlaTted at Cape Grim (41'S) and at the GMCC slalions BRW 

(7l'N). MLO (20'). SMO (14'5) and SPO (90'S). The Cape 

Grim observations constitute the foundation measurements, 

along with contiguous in·siru observations of all species of 

interest, including in·situ CO2 extraction for isotopic ratios 

[Francey and Goodman. 1986]. At the GMCC slations. 

comparisons of flask CO2 measurements with in-situ COl 

9 1 

observations are used as a basic quality control. 

Sample collection has continued uninterrupted with both 

NERDOC and CSIRO financial suppon. and has expanded 10 

include Alert (82"N, in cooperation with AES), Macquarie 

[Sland and Mawson (54"S and 68"S respectively, with logistic 

suppon from ANARE). and Niwol Ridge (NWR. 40'N. in 

cooperation with GMCC). Throughout, similar techniques have 

been employed to collect monthly samples from aircraft at about 

4-km altitude over the ocean southeast of the Australian 

mainland. 

3. METIIODS 

Sampling equipment at each collection site comprises a 

Teflon-diaphragm pump with an anhydrous magnesium 

perchlorate drying tower on the inlet, connected to the station air 

intake mast. The sample containers are Sol-capacity glass 

flasks, fitted with two Teflon O.ring glass barreled taps, one 

connected to an internal flushing tube. In suitable conditions 

(typically winds greater than 4 m s·1 (9 mph), and fTom a "clean 

air" sector), flasks are connected to the pump unit one at a time, 

flushed for 15 minutes at about 2 L min· I , then pressurized to 1 

aun above ambient. Station operators record synoptic condi· 

tions and the preliminary in·situ CO2 concentration. 

Flasks are returned to Aspendale for analysis. The flask 

overpressure facilitates gas chromatographic analyses with a 

Hewleu·Packard 5890 Porasil column and ECD for N20, CCI)F 

(CFC-ll). and CCI,F,. (CFC-12) and with a CARLE Model 

211S 5A molecular sieve column and flO for COl' CH4 , and 

CO. The remaining bulk of the air from the flask is then drawn 

through a cryogenic extraction line that collects the COl for 

mass spectrometer analysis (Francey and Goodman, 1986]. A 

stable isotope ratio Micromass 6020 mass spectrometer is used 

to determine the SI3C and SI8() ratios. 

All measurements are made with respect to in·house working 

standards that are routinely calibrated against international 

standards. The gas chromatograph standards are tied to the 

OGC scale [Rasmussen and Lovelock. 1983] and NIST 

standards [Rasberry and Reid, 1984]. The mass spectrometer 

standard has been calibrated against the international POB scale 

using NIST carbonate, and checked in a number of inter· 

laboratory comparisons (Francey and Goodman, 1988]. 

4. RESULTS 

Because of the relatively low sampling rate compared with 

other extensive overlapping networks (in particular the 

ALE/GAGE programs). the CFC-ll and CFC-12 clala are used 

only for diagnostic purposes, and since 1987 they have not been 

routinely measured from those stations with in-situ programs. 

This is also the situation with NzO, with the exception that the 
NzO mixing ratios are used to make a second-order correction 

for a mass 44 contribution to Lhe COz isotope ratios in Lhe mass 

spectrometer measurements [Mook and Jongsma, 1987]; when 

data are not directly available from Lhe flasks, a linear plus 

harmonic regression of the in-situ data from each station is used 

for this purpose. 

The GC analysis of COz is Lhe main diagnostic for Lhe 

assessment of integrity of Lhe flask sample. For COz of 

biological origin, mixing with Lhe atmosphere is characterized 

by approximately 0.05% ~r ppm (by mole fraction) linear 

relationship, where Lhe precision on an individuall513C analysis 

is 0.03-0.05%. This means that COz determinations to better 

than I ppm are adequate for quality control; this is achieved 

with the CARLE GC. 

Figure 1 shows the raw, flask CO2 data (ppm) from the 

commencement of the records to the end of 1987. Solid lines 

connect the preliminary in-situ measurements reported at the 

measurements from O.5-L glass flask samples using an NDIR 

360 

350 

340 

345 

+ + 

+ + 

t + N++ ... + .... +j 345 + .. ,+, •. ~t + ++ ~T· t T ·•· 14'S 

34J 

340 [ 

345 

340 

345 t 

340 

345 t 

# 

40·'S 

~~j 54'S 

68'S j • 

• 345 

340 

~......... II ------~. ._-

90'S 

1984 1985 1986 1987 

Fig. I. Measured CO2 in 5·L flasks (symbols) compared with 

preliminary in·situ values Oines) for the csmo network and aircraft 

(39"5). This illustrates the density of sampling and quality of sampling 

and storage. 

92 

time of flask filling, When in-situ CO2 data were not 

available··aircraft (39·S) and Mawson (68·S) .. bracketing COz 

analyzer [Beardsmore 1984] were used. The presentation of the 

raw data in this form serves to illustrate the following: 

(1) The overall coverage and frequency of sampling. 

Typically, pairs of flask samples are collected at least every 

third month, and individual samples are collected during 

intervening months. 

(2) Systematic errors, of varying seriousness, which appear 

from time to time. Examples include enhanced CO2 at 71"N 

during most of 1984 and 1985, and occasionally at 41·S and 

900S, due to laboratory air from pump unit leaks; depleted COz 

at 54"S in 1986 and at 14"S in early 1987, thought to be due to a 

saturated drying tower; a shift in GC calibratition around 1986; 

difficulties with preliminary in-situ values at 14"S and 90·S 

(normally, corrected monthly averages are available on these 

occasions). 

The periods of affected data are limited, and it is evident 

from Figure 1 that the quantity and quality of data are approach· 

ing levels sufficient for the determination of latitudinal 

gradients, and of seasonality at most stations. 

Only preliminary results for CH4 [Fraser et al., 1986al, CO 

[Fraser et al., 1986b], and isotopes [Francey and Tans, 1987; 

France:y el al., 1988} have been published; a more comprehensive summary of Lhe isotope results [Francey el al., submitted] 

will appear shortly. An assessment of flask pcrfonnance is 

given by Mansbridge et al. [1988}. It is intended that this paper 

act as a general reference for specific results to be presented in 

future GMCC reports. 

REFERENCES 

Beardsmore, D.I., G.!. Pearman, and RC. O'Bricn, The CSIRO 

(Australia) Atmospheric carbon dioxidc monitoring program: 

Surfacc data, Division of Atmospheric Research Technical Paper 

No.6, 115 pages, CSIRO, Aspendale, Victoria, Australia, 1984. 

Francey, R.I., and H.S. Goodman, Systematic errors in, and selection of, 

in situ SI3C, Baseline 1983·1984, edited by PJ. Franccy and 8.W. 

Forgan, pp. 27-36, Australian Department of Sciencc/Bureau of 

Meteorology in cooperation with csmo Division of Atmospheric 

Research, Aspendale, Victoria, Australia, 1986. 

Francey, R.I., and H.S. Goc:x1man, The DAR stable isoptope reference 

scale for COz, Baseline 1986, edited by B.W. Forgan and PJ. 

Francey, pp. 40·46, Australian Department of SciencelBureau of 

Meteorology in cooperation with CSIRO Division of Atmosphcric 

Rcsearch, Aspendale, Victoria, Australia, 1988. 

Francey, R.I., and P.P. Tans, Latitudinal variation in oxygen·18 of 

atmospheric CO2, Nature, 327, 495·497, 1987. 

Francey R.I., G.I. Pearman, and D.l. Beardsrnore, A southern view of 

the global atmosphere, Papers Proc. Roy. Soc. Tas"umUJ, 122(1), 

113·119,1988. 

Francey, R.I., FJ. Robbins, C.E. Allison, and N.G. Richards, The 

CSIRO global survcy of COz stable isotopes, edited by S.R. Wilson 

and G.P. Ayers, Baseline 1988, Bureau of Meteorology in 

cooperation with CSIRO Division of Atmospheric Research, 

Aspendalc, Victoria, Australia, submitted, 1989. 

Fraser P.I., P. Hyson, R.A. Rasmussen, AJ. Crawford, and M.A.K. 

Khalil, Methane, carbon dioxide and mcthylchlorofonn in the 

Southern Hcmisphere, lA/mos. Chern., 4, 3·42, 19800. 

Fraser PJ, P.Hyson, S. Coram, RA. Rasmussen, AJ. Crawford, and 

M.A.K. Khalil, Carbon monoxide in the Southern Hemisphere, Proc. 

7/h WorldC/ean Air Congress, 2, 341·352, 1986b. 
Kceling, CO. , R.B. Bacastow, and P.P. Tans, Predictcd shift in 

the I3C/'2C ratio of atmospheric carbon dioxide, Geophys. Res. Lell., 

7,505·508, 1980. 

Mansbridge J.V, FJ. Robbins, and PJ. Fraser, Variation in measure· 

ments of methane, carbon dioxide and carbon monoxide from Cape 

Grim flask samples, Baseline 1986, edited by B.W. Forgan an PJ. 

Francey, pp. 27·34, Australian Department of SciencelBureau of 

Meteorology in cooperation with CSIRO Division of Aunospheric 

Research, Aspendale, Victoria, Australia, 1988. 

93 

Mock, W.G., and 1. Jongsma , Measurement of the NzO correction 

for 13CJl2C ratios of aunosphcric COz by removal of NzO, Tellus. 

398,96·99, 1987. 

Peannan, G.P. , and P. Hyson, Global transport and inter.rcservoir 

exchange of carbon dioxide with particular reference 10 stable 

isotopic dislributions, J. Almos. Chem., 4,81-124,1986. 

Rasberry, S.D., and W.P. Reid, Reference materials and environmental 

analysis, Environ. Int .• 10, 87 - 90, 1984. 

Rasmussen, R.A., and 1.E. Lovelock, The Aunospheric Lifelime 

ExpcrimeOl, 2. Calibration, J. Geophys. Res .• 88, 8369-8378, 1983. 
Global Aurora Dynamics Campaign 

K. HAYASm 

Geophysics Research Laboratory, University ofTolcyo, Japan 

I. INTRODUCIlON 

To study magnetospheric and ionospheric physics, a research 

group of the Geophysics Research Laboratory, University of 

Tokyo. has conducted campaigns of multistation observations in 

North America every 34 years for the last 15 years. Groundbased multistation observations provide two-dimensional, 

spatial and temporal, information. although the information is 

more or less spatially integrated and must be processed with 

remote sensing techniques. These observations also increase the 

chances of obtaining three-dimensional multipoint data when 

they are coordinated with satellite observations. 

2. THE 1985-1986 CMAPAIGN 

The last campaign, named Global Aurora Dynamics 

Campaign, was carried out from December 20, 1985, to 

<OR 

210 

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\ 

/ 

/ 

/ 

/ 

/ 

, .J, 

\ 

>- - \ - , 

/ 

/ 

\ ... , .;-

240 \ \ 

, 

, \ , , \ , 

\ , , , , v , , 

" 

~ , 

~ 

120 

February 3, 1986. at 43 stations (Figure 1). The research 

objectives of the campaign were to study (1) the global 

dynamics of auroras, (2) the generation and propagation of 

ULF-VLF waves in connection wiLh auroral activities, (3) the 

relationships of simultaneous observations from the ground with 

those from satellites in the ionosphere and in the magnetosphere, 

(4) the energetics in the ionosphere-magnetosphere coupling 

system including wave- particle interactions. and (5) the 

propagation of ULF waves on the global scale, whether related 

to auroral activities or not. The campaign was organized by 

Geophysics Research Laboratory, University of Tokyo; the 

Department of Physics, Kyushu University; and the Department 

of Geophysics and Astronomy, University of Geophysics and 

Astronomy. It was supported by the members of the Data 

Analysis Center for Geomagnetism and Spacemagnetism, Kyoto 

University; Department of Engineering. Takushoku University; 

Upper Atmospheric Division, National Institute of Polar 

60 

\ 

\ 

\ \ \ 

\ \ 

\ 

30 

27 0 - _ 1 __ 330 

300 

Fig. 1. Distribution of the campaign stations. The circled stations are the key stations. The circle approximately indicates the coverage of an all-sky 

TV camera from each station with elevation angle larger than 10-. 

94 
Research; Department of Physics and Astronomy, University of 

Victoria; Institute of Space and Atmospheric Studies, University 

of Saskatchewan; Department of Atmospheric Sciences, State 

University of New York. Albany; Geophysical Institute, 

University of Alaska; Department of Physics, University of 

Oslo; Norwegian Polar Research Institute; and Danish 

Meteorological Institute. 

Nine of the 43 stations in the campaign network operated an 

all-sky TV camera, a VLF receiver, an induction magnetometer, 

and a fluxgate magnetometer. At 34 stations magnetic fields 

were measured with an induction and/or a fluxgate magnetometer(s). An introduction magnetometer was installed and 

continuollily operated for 6 months at GMCC site at BRW 

where it could provide micropulsation information from the 

westernmost Arctic region in the global network. The 

campaign, specifications of instruments, data periods, and 

station descriptors are summarized by Oguti et al. [1988aJ. The 

campaign period was originally planned to overlap with 

Swedish VfKING satellite program, but the VTKlNG launch 

was unfortunately delayed until February 22, 1986. Coordination with magnetic field observations onboard U.S. meteorological satellites in synchronous orbit, the GOES 4 and GOES 6, 

was successful at Great Whale River, Shamattawa, La Ronge, 

and Rabbit Lake, near the geomagnetic lines of force. 

Analysis of data, 1000 video tapes and 600 cassette tapes, is 

still in progress. All initial results were published in a special 

issue, "Global Aurora Dynamics Campaigo," in the Journal of 

Ceom.agnetism arui Ceoelectricity, Vol. 40, No.5, 1988. The 

main results are related to the following: the first auroral 

evolution and related magnetic field changes (Oguli et ui., 

1988b); dynamic characteristics of [PDP magnetic pulsations 

(lfayashi el al., 1988], auroral activities and long-period 

geomagnetic pulsations {Yamamoto el al., 1988a, b], auroras 

and bursts of magnetic pulsations in the dayside cusp [Kokubun 

e/ al., 1988). 

2. THE 1988-1990 CAJ,jpAIGN 

In conjunction with a satellite program named EXOS 0, 

which was launched in semipolar orbit on February 22, 1989, a 

new campaign of multistation observations is planned for 

December 1989 to January 1990. In the summer of 1988 an 

induction magnetometer was teprarily installed at BRW, and a 

test run was made. Problems with the recording system were 

discovered. The pennanent installation and operation of a 

induction magnetometer at the BRW site was proposed for use 

in the campaign, and it was approved in 1988. The faulty 

recording system was replaced in August 1989. 

REFERENCES 

Hayashi, K., T. Yamamoto, S. Kokubun, T. Oguti, T Ogawa, N. 

lwagami, T. Araki, T. Kitamura, O. Saka, K. Makita, N. Sato, T. 

Watanabe, R.E. Horita, D. McEwen, 1.5. Kim, and A. Egeland, 

Multi-station observation of IPDP mieropulsations--Twodimensional distribution and evolution of the source regions, J. 

Geomagf1 . Gecnlectr., 40, 583-619, 1988. 

Kokubun, 5., T. Yamamoto, K. Hayashi. T. Oguti, and A. Egeland, 

Impulsive Pi bursts associatcd with poleward moving auroras ncar 

the polar cusp, J. Geomagf1 . Ceoeleelr., 40, 537-551, 1988. 

Oguti, T, T. Kitamura, and T. Watanabe, Global Aurora Dynami cs 

Campaign, 1985- 1986, J. Geomagf1 . Ceoe/eetr .• 40, 458-504, 19880. 

OgUli, T, T. Yamamoto, K. Hayashi, S. Kokubun, T. Ogawa. N. 

Iwagami, T. Kitamura, O. Saka, T. Araki, K. Makita, N. Sato, T. 

Watanabe, R.E. Horita, and 1.5. Kim. Fast auroral evolution and 

related magnetic fields changes on the ground and at conjugale 

satellites, J. Ceomagf1. Gecnleclr., 40, 505-536, 1988b. 

Yamamoto, T., K. Hayashi, S. Kokubun, T Ogutl, T. Ogawa, N. 

Iwagami, T. Kitamura, O. Saka, T. Araki, K. Makita, T. Watanabe, 

R.E. Horita, and I.S. Kim, Auroral activities and long period 

geomagnetic pulsations, I, Pc5 pulsations and concurrent auroras in 

the dawn seelor,J. Ceomagf1 . Ceoeleclr. , 40, 553-569, 1988a. 

95 

Yamamoto, T., K. Hayashi, S. Kokubun, T. Oguti, T. Ogawa, N. 

Iwagami, T. Kitamura, O. Saka, T. Araki. K. Makita, T. Watanabe, 

R.E. Horita, and 1.S. Kim, Auroral activities and long period 

geomagnetic pulsations. 2. Ps5 pulsations foll owi ng auroral breakup 

in the premidnighl hoors, J. Ceomagn.. Ceoeleelr .• 40, 571 -582, 

1988b. 
The Colorado State University Multiple Field of View Radiometer 

at the Mauna Loa Observatory 

PAUL F. HEIN AND STEPHEN K. Cox 

Colorado State University, Department of AtmospIJeric Science, Ft. Collins. Colorado 80523 

The MFOV was developed at Colorado State University to 

determine the bulk scattering properties of clouds by measuring 

the solar irradiance in different fields of view. The MFOV 

consists of five silicon photodiodes aligned along a common 

optical axis (Figure 1). Collimator tubes of different lengths 

give each of the photodiodes a different field of view (2", 5·,10", 

20·, and 2SO). The photodiodes have a spectral range from 0.35 

to 1.15 micrometers. The MFOV tracks the SWl wiLh a LICOR 

microprocessor-based solar tracker. 

The MFOV data set for MLO extends from January 1985 to 

the present. The MFOV has been running nearly continuously, 

having an estimated 90% up time. The data collected for each 

photodiode consists of a lO-min average voltage, and a standard 

deviation, a minimum, and a maximum voltage for the period. 

The MLO data set from May 1985 to June 1986 was 

analyzed by Combs [1988]. From the analysis of solar energy 

depletion at different fields of view, the mean daily irradiance 

and its standard deviation for the 100 field of view appear to 

c A 

" " 

I..bd Dc.scription 

A Photodiode 

81 Collimalot lUbe for 2" 

82 CollimalOf lUbe for S' 

83 CollimalOflUbefor2S"C 

84 Collimllor lUbe [or20"C 

55 CollimllOflUbeforlO' 

C Pluigla.u weatber--proof easing 

D Op amp pc bowd 

E Visual alignment due 

F Mounting urn 

G Cable hookup 

Fig. 1. The multiple field of view radiometer. 

" • 

• 

• 

" ... ~ 

" ~ " } I. 

~ " 

" 

--------,--,---,----- Fig. 2. Voltage versus time for thin clouds on March 30, 1986, using 

the 5" and 10' fields of view. 

~ 

• 

• 

u 

\(\J ... II 

" .11 11 

f\ 'rv M M J. 16 

• i I. M fJ, > 

96 

" II' " f\v\ rJ, 

f 500 60,) 100 100 900 lOCO IIOO'-IODllloJ l"IXlISC() 1600 noo 1Il00 1900 2000 lJoo 2lOO 

T ...... Hoon 

Fig. 3. Voltage versus time for broken cloud cover on Marchl8, 1986, 

using the 5' and 10' fields of view. 

provide a useful way to categorize generic cloud cover 

infonnation. Each type of cloud cover had a separate range of 

depleted energy. Figures 2 and 3 are examples of the MFOV 

output. 

REFERENCES 

Combs, C. L., Transmittance of solar radiation detennined by the 

multiple field of view radiometer, M.S. Thesis, 16 pp_, Colorado 

State University, Ft. Collins, 1988. 
The Global 4He Content of Near-Surface Atmospheric Air 

P.W. HOLLAND Al\D D.E. E~ERSON 

u.s. Department of the Interior. Bureau. of Mines, Heliwl1 Fjeld Operations. Al7UJrjl/o, Te:cas 79101 

In a cooperative program with GMCC, the Bureau of Mines 

obtained near·surfacc 8lmosphcric samples from five locations 

around the globe for subsequent 4He analysis. The study was 

conducted to verify the constancy of the worldwide 4He-in-air 

content and to provide a more accurate absolute value. The 

aunosphcric samples were obtained from Hilo, Hawaii; Barrow, 

Alaska; Paga Page. American Samoa; Mangilao. Guam; and 

Amundsen-Scott South Pole Station, Antarctica. Samples were 

collected from March 26. 1985. through February 5. 1988. 

The study showed the 4He content in lhe lower atmosphere to 

be constant al 5.2204 ± 0.0041 ppmv. This value is 0.0186 

pprnv lower than the currently accepted global average of 5.239 

± 0.004 ppmv reponed by Glueckauf[1946]. but agrees with the 

values of 5.222 ± 0.107 ppmv and 5.2204 ± 0.0041 ppmv 

reported by Oliver et ai. [1984] and Hoiland and Emerson 

[19871, respectively, for atmospheric samples collected within 

the continental United Slates. 

97 

The global 4He content in the lower atmosphere was 

determined to an absolute accuracy of ±O.0041 ppmv at the 68% 

confidence level. This accuracy was achievable using a 

specially modified 4Hc mass spectrometer. The precision of this 

instrument for a 5-ppmv 4He concentration is routinely ±O.OOI 

ppmv. The mass spectrometer was calibrated using gravimetrically prepared 4He-in-nilrogen standards accurate to within 

± 0.003 ppmv. 

REFEREI\CES 

Glueckauf, E., Micro-analysis of the helium and neon contcnts of air, 

Proc. R. Soc. London, Ser. A.l85, 98-119,1946. 

Holland, P.W., and D.E. Emcrson, A dctcnnination of thc helium-4 

content of near-surface atmospheric air within the continental Un itcd 

Slatcs,J. Geophys. Res., 92,12557-12566,1987. 

Oliver, B.M., J.G. Bradley. and U. Farrar IV. Helium concentrati on in 

the earth's lower atmosphere, Geochim. Cosmochim. ACla, 48, 

1759·1767. 1984. 
Nitric Acid and Aerosol Nitrate Variations at Mauna Loa 

B. J. HUEBERT, G . L. LEE, AND W. M. WARREN 

University o/Rhode Island, GradutJte School o/Oceanography. No"ogansell, Rhode Island 02882.} 197 

R. B.NoRTON 

NOAA, Aeronomy Labora/ory, Boulder, Colorado 80303 

1. INTRODUCTION 

Much of lhe NO and NOz that 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; therefore, in remote areas such as MLO, lIle total 

nitrate concentration (vapor plus aerosol) represents a fair 

estimate of the total cxld-nitrogen concentration (Galasyn el 01., 

1987a, b; Robinson and Harris, 1987). 

With support from NSF, we measured nitrate concentrations 

at MLO for severa1 years. to help identify the important sources 

of odd-nitrogen compounds in remote parts of the globe. In 

1988 we sampled intensively from the new walkup tower during 

the May-June MLOPEX experiment. We also changed from an 

intcnnittent 10 a nightly sampling sttategy in the late summer. 

We are now measuring total nitrate every night. in collaboration 

with the MLO staff. 

2. MATERIALS AND METHODS 

We use a Teflon/nylon filter pack method for collecting 

atmospheric nitrate. Initially, the filter packs were exposed by 

our sequential sampler during 8-day visits to the site by 

researchers approximately every 2 months. Since August 1988, 

one filter is being exposed each night. from 2000 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 were influenced by local sources on 

the island. 

3. RESULTS AND DISCUSSION 

3.1. MLOPEX EXPERlMEKr 

For about 6 weeks in May and June, we measured nilric acid 

and nilrate aerosol during five daily sampling periods, at three 

MLO locations. We found that samples taken from the deck 

atop the AEC building often had concenlJations significantly 

different from those taken at the 23-m level of the tower, 

probably as a result of surface losses and turbulent flow over the 

irregular terrain. Gradients on the tower were unpredictable. 

sometimes showing the expected higher concentrations at higher 

altitude, but occasionally inverting to give slightly higher 

concentrations at 4 m than 23 m. 

Two episodes are evident in Figure I: the first (days 139-

142) was characterized by visible haze, some very high CN 

counts (Figure 2), and high dewpoints; the second (days 143-

146), by contrast, was very clean and dry, and had relatively 

high ozone. Although we suspect that upper-tropospheric air 

was pre..,ent during the second event, we are still working on 

piecing together the history leading to both events. These 

events (and results from some 1989 CPACE flights in the 

vicinity using NCAR's Electra) suggest that the free troposphere 

is highly inhomogeneous even in the mid-Pacific, having a thin 

laminae of widely varying composition. 

The existence of the high-concentration events at MLO 

suggests that our initial sampling strategy (8-10 days, once 

every 2 months) was incapable of defining the cJimatology of 

nitrate concentrations at MLO. In collaboration with the MLO 

staff, we initiated a nightly sampling progranl, and so our data 

are now more representative. 

< 00 -,-------------------------------------------------------------------------, 

300 -

::::~o -

E 

~ 

::!oo - ~ 

0 

~ >50 

100 -

'0 -

0 ". 

0 

c 

0 

c 

c 

0'" o 

0 00 So~'b o _ '" Co c ... 

o '" 

c 

c 

o c c 0 

o c 

00 

o o ",,0 

JUU ......... O .... T£ 

c 

c 

c 

0'3 

,.. 

c 0 

o c 

o 

Fig. 1. Nitric acid versus lime during MLOPEX. 

98 

", 
.. co 

»0 ~ 

=0 ,,0 V 

0 

> ~o • ~ " ~ 

~ ~co 

0 

~ 

'" • • " " ,., 

• • .. 0 

'00 

'0 

0 J 

~ ~..". 

. ~ • .... T 

.... ~..pI-~~~.,.. + + ~ 

+ T~"1":+.ir!""" .... .~ +--++ 

+ + 

± 

o 

0 0.2 o.~ 0.6 o.a ':-rha .... a .... d.) 

o CLEAN EVENT CNC/Ut,. (1000 ".-nIt) 

4 HAZE EVENT BACKGROUND 

Fig. 2. Nitric acid versus CNC during MLOPEX. 

900 

.00 

:;00 

ii: 6CO 

~ 0 

,.; ~co ~ 

~ " • .00 0 

~ " 

':!o 0 " " 

g >00 0 " "0 

" 

-

::00 " iP.. 0 

'00 

,,~~ " 

" 

" 

.g 

~ 

" 0 

::00 ::::~o ::!:150 "0 360 •• 0 .=.::::0 

.JUUAN OATC (5INCC 1/1/aa) 

Fig. 3. Total nitrate versus lime, August 1988·May 1989. 

3.2. ANl'-o'UAL VARlATION 

During all MLO sampling, 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 

sLimulate our science. 

Although our nightly sampling has not yet completed a full 

year, it appears that the same trend is evident in these data. 

Figure 3 shows 2000 to 0800 LST concentrations of total nitrate, 

starting in August 1988 and ending in May 1989. The lowest 

sustained concentrations are still evident in the winter, and a 

mix of high-concentration events and clean periods occurs in the 

spring and late summer. 

4. ONGOING RESEARCH 

We are continuing our inclusive nightly sampling from the 

tower, with the help of the MLO staff. AJthough equipment 

99 

failures and bad weather (which prevents 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. 

REFERENCES 

Ga lasyn, 1.F., K.L Tschudy, and B.l. Hucben, Seasonal and diurnal 

variability of nitric acid vapor and ionic aerosol species in the remOle 

free troposphere at Mauna Loa, Hawaii, J. Geophys. Res., 92, 

3105-3113,19810. 

Ga lasyn, J.F., K.L Tschudy, and BJ. Hueben, Authors' Reply to the 

Comment of Robinson and Harris, J. Geophys. Res., 92, 14868, 

1981b. 

Robinson, E., and 1. Harris, Comment on "Seasonal..." by Galasyn, 

Tschudy, & Huebert, J. Ceophys. Res. , 92, 14,865-14,867, 1987. 
Nitrogen Oxide Measurements at Barrow 

DAI\%L A. JAFFE AND RICHARD E. HONRATH 

University of Alaska. Departmenl o/Chemistry and Geophysical Insti/uJe, Fairbanks. Alaska 99775·0800 

1. INTRODUcnON 

NilIogen oxides are critical in the chemistry of the 

lroposphere. At NOll (NO+N01) concentrations greater than 

about 30 ppLV, net 0) production can occur [Fishman et al., 

1979; Liu el al., 1987}. OJ is a radialively and chemically 

important gas, and its tropospheric concentration in the northern 

hemisphere is increasing at approximately 1% yrl [Ollmans and 

Komhyr, 1986; Logan, 1985]. At BRW, the surface 0) increase 

is observed only during summer, when the rate is approximately 

2% yr' [Ollmans and Komhyr, 1986]. 

The well-known occurrence of Arctic haze, the transport of 

middle-latitude pollution to the Arctic, is primarily a 

winter-spring phenomenon. During summer, measurements of 

inert continental tracers such as 210Pb [Larsen and Feely, 1986]. 

chlorinated hydrocarbons. and chlorofluorocarbons [Khalil and 

Rasmussen. 1984] indicate that long-range transport to the 

Arctic from the middle-latitudes is least efficient. This 

observation has prompted the suggestion that Arctic sources of 

N01 may be responsible for the observed Barrow surface 0) 

increase [Jaffe and I/oflfalh, 1988]. 

2. EXPERIMENTAL DETAILS 

Measurements of NO and NOy (sum of all reactive nitrogen 

oxides, NO+N02+HNO)+PAN+ ... ) were conducted at the 

GMCC BRW si.e during July and Augus. 1988, using a 

high-sensitivity chemiluminescent instrument built at the 

University of Alaska. similar in design to that prev iously 

reported [Kley and McFarland, 1980; Ridley eI 01., 1987). 

Measurements of NOy were conducted by means of thennal 

conversion of the NOy compounds to NO at 375"C on a 

commercially available molybdenum mesh converter. A flow 

diagram of the chemiluminescent instnunent used for these 

measurements is shown in Figure 1. 

This was the fl1st field measurement campaign attempted 

with this instrument, and overall we were pleased with the 

result. However, several problems were encountered that limit 

the accuracy of the data. A variable insLrument artifact was 

observed, which was not corrected by the zeroing process. This 

artifact was observed to be approximately ±SO pptv, limiting the 

absolute accuracy of the data to approximately this leve1. 

AdditionaJly, uncertainties in conversion efficiency limit the 

NOy accuracy to approximately 30%. Design changes in the 

chemiluminesccnt instrument were made that reduce these 

uncertainties considerably. 

In addition to the data quality, a primary concern in the 

development of this instrument is that it be able to run with 

minimal supervision. To this end. data collection. calibration, 

and zeroing functions are all perfonned automatically by a 

PC-AT (286) microcomputer. During the approximately 6-week 

summer 1988 measurement campaign, University of Alaska 

personnel were on site for approximately 3 weeks. After this 

100 

Air Inl eis 

NO y Conv erter 

f=l--. To Pump 

Calib ration 

Standard 

Vent 

Scrubbed 

Oxygen 

Pre reactor 

:::::::::::: 

Photomultiplier 

Tube 

e3 Solenoid Valve 

IMFC I Mass rlow Con/roller 

Reaction 

Chamber 

To 

Pump 

Fig. 1. Schemalic or Ihe NO/NOy chemiluminesccnl instrumenl. 

initial period, GMCC personnel performed minor daily checks 

on the instrument. 

3. RESULTS 

During the summer of 1988. an unusual predominance of 

winds with a southwesterly component was observed, resulting 

in a number of observations with very high NO and NOy 

concentrations. presumably due to local emissions from the 

town of Barrow. A time series of the hourly-averaged measUJed 

NO and NOy concentrations is shown in Figure 2. Maximum 

concentrations of NO and NOy of 6.5 ppbv and 13.7 ppbv were 

observed. corresponding to locally polluted air. 

However. despite the unfavorable wind conditions. a large 

number of very low concentrations were observed. Because the 

chemiluminescent instrument makes numerous repetitive 

measurements during each 100·s cycle, we can screen lhe data 
NO 

Date (local so lar time) 

Fig. 2. Hourly averages or the un screened NO and NOy data. 

on the basis of the observed variability (as compared with what 

we would expect due to photon-counting statistics alone). 

Those observations with high variability are very likely 

contaminated by local pollution [Bodhaine et ai., 1981]. 

Screening the data for high variability reduces the incidence of 

high NO and NO), concentrations considerably. Additionally. 

we can use only data fTom the local "clean air" sector between 

45' and 130' [Bodhaine et al., 19811. Figure 3 is a histogram or 

the data screened by variability and wind direction. The 

median, mean, and standard deviation of the NOy concentrations 

from the clean-air sector are 100, 120, and 60 pptv. NO 

concentrations in the clean-air sector were generally below our 

detection limit (50 pptv), having a maximum of 100 pptv. 

A small, but statistically significant diurnal trend was 

observed, greater NOy concentrations being observed during the 

day. The mean daytime NOy concentration is 140 pptv, 

approximately 40 pptv greater than at night. 

4. DISCUSSION AND FUTURE WORK 

NOy concentrations observed at BRW in the clean-a ir sector 

during summer 1988 were generally very low, and comparable 

with those at other remote locations where similar 

measurements have been conducted. During this measurement 

period, no evidence for pol1ution sources outside of the BRW 

vicinity was observed. The diurnal cycle of NO), concentrations 

at BRW may have several causes, including the following: 

(1) Biogenic production of NO), compounds. 

(2) Diurnal changes in the mixed layer. 

(3) A diurnal cycle in fog scrubbing of water soluble NOy 

species (e.g .. HNO,). 

Measurements of these important compounds at BRW will 

continue during 1989 and 1990 as an aid to elucidating 

aunospheric chemical pathways and processes. 

g,--------------------------------, 

o 

o 50 100 150 200 250 300 

Concentration (ppt) 

Fig. 3. Ilistogram of me screened (clean-sector) NO), mea surements. 

Ackrwwledgmenl. The authors would like to acknowledge 

assistance from GMCC personnel and the North Slope Borough. 

This work was supported by NSF grant ATM 88145 18. 

101 

REFERENCES 

Bodhaine, B.A., J.M. Harris, and G.A. Herbert, Aerosol light scallering 

and condensation nuclei measurements at Barrow, Alaska, Almos. 

Environ., 15, 1375-1389, 1981. 

Fishman, 1., S. Solomon, and PJ. Crutzcn, Observational and theoretical 

evidence in support of a significant, in-situ photochemical sou rce of 

tropospheric ozone, Tel/us, 31, 432-446, 1979. 

Jaffe, O.A., and R.E. Honrath, Ozone in the Arctic troposphere, 

American Geophysical Union, Fall Mccling, San Francisco. 

Decembc, 1988, £05, 69(44), 1078,1988. 

Khalil, M.H.K., and R.A. Rasmussen, Statistical analysis of trace gases 

in the Arctic, Geophys. Res. utI.. JJ, 437·440, 1984. 

Kley, D., and M. McFarland, Olemiluminescence detector for NO and 

N02, Almos. Technol., 12, 63-69,1980. 

Larsen, R., and H. Feely, Seasonal variation of 210Pb and 7Be at Mauna 

Loa and Barrow, Geophysical Moniloring for Climalic Change, No. 

14: Summary Report 1985, NOAA Air Resources Laboratory, 

Boulder, CO, 1986. 

Liu, S.c., M. Trainer, F.C. Fehsenfeld, D.O. Parrish, EJ. WiUiams, 

O.W. Fahey, G. Hubler, and P.C. Murphy, Ozone production in me 

rural troposphere and the implications for regional and global ozone 

distributions,!. Geophys. Res., 92, 4191-4207,1987. 

Logan, J.A., Tropospheric ozone: Seasonal behavior, trends, and 

anthropogenic influences, J. Geophys. Res. , 90, 10,463-10,482, 1985. 

Oltmans, S., and W.O. Komhyr, Surface ozone distributions and 

variations from 1973- 1984 measurements at me NOAA Geophysical 

Monitoring for Oimatic Change ba seline observatories, J. GeopJiys. 

Res., 9/, 5229·5236, 1986. 

RidJey, B.A., M.A. Carron, and G. L. Gregory, Measurements of nitric 

oxide in me boundary layer and free troposphere over me Pacific 

Ocean. J . Geophys. Res., 92, 2025-2047,1987. 
Estimates of Uncertainty in Trajectory Ensembles 

JONATHAND. KAHL 

NRC Research Associalt', NOAA/GMCC, Bowder, Colorado 80303 

1. INTRODUCIlON 

A modeled trajectory represents the estimated pathway of an 

individual air parcel. An ensemble of trajectories represents a 

lime-history. or climatology, of air parcel transport. Although 

individual trajectories have known uncertainties resulting from 

spatial and temporal interpolation of meteorological data [Kahl 

and Samson, 19861. trajectory ensembles are thought to benefit 

from the partial cancellation of random interpolation errors. The 

purpose of this paper is to demonstrate a means for estimating 

the residual uncertainty in trajectory ensembles. 

We followed a concept introduced by Samson and Moody 

[1981] that considers a trajectory to be the cenler of mass of a 

locus of possible paths, Figure 1 shows 1000 stochastic 

trajectory endpoinlS clustered about an analytical trajectory 

based on a simple, artificial wind field (a 5 m S·l westerly wind 

over the entire domain, invariant with time). The stochastic 

trajectories were generated by randomly perturbing the wind 

field, using statistical properties of wind interpolation errors 

[Kahl and Samson, 1986]. Note that the cluster of trajectory 

endpoints diffuses as it is advected from the point of origin. The 

diffusing clusters depict the increasing error, with time, in 

modeled trajectories using interpolated data. 

The along wind and crosswind error diffusivities Kit and K" 

derived from the spread of the normally-distributed stochastic 

trajectory endpoinlS as a function of time, are 1.5 x 10' m2 S·I 

and 2.0 x lOS m2 S·I, respectively. The lateral trajectory error 

diffusivity K, is 4 times greater than the large-scale eddy 

Zq H 

" . ' .... 

:.' 

Fig. I. Stochastic trajectory endjXIints after 12,24.36, and 48 hours of simulated travel. The solid line is the analytical trajectory; arrows are 

drawn at 6 h intervals. The largest arrow on each trajectory indicates the "true ~ location. 

102 
diffusivity reported in Gifford's [1977] summary of tropospheric 

diffusion data. This implies that the downwind spread of 

estimated trajectory endpoints is twice as great as the dispersion 

of material about a trajectory. This result has important 

implications for the confidence that one may place in trajectory 

ensembles. 

In describing atmospheric transport, trajectories represent the 

mean pathway of a cloud of windborne material. Turbulent 

diffusion causes the cloud dimensions to grow with time. Since 

the uncertainty in estimating the center of mass of a cloud of 

airborne material (i.e., the trajectory) is greater than the 

diffusive spread of material about that center of mass, there 

must be an upper limit to the accuracy of long.range 

atmospheric transport and diffusion calculations based on 

IrajectOl'Yensembles. In olher words, even if it were possible to 

estimate diffusion with complcte accuracy, a certain amount of 

error would still remain because of the uncertainty in estimating 

trajectories. 

2 . METHODOLOGY 

A model was developed to define lhc uncertainty in trajectory 

ensembles as applied to lhe estimation of impact areas 

downwind of a passive, nondepositing atmospheric pollutant 

source, Full details and equations were given by Kahl [1 989]. 

The model estimates the percent accuracy. or confidence, in 

the identification of impact areas downwind of a continuous 

pollution point source, We begin with thc stochastic trajectory 

cnsemblc shown in Figure 1. Each stochastic trajectory has a 

probability of occurrence that decreases isotropically from thc 

"IruC" trajectory. At discrete times downwind of thc pollutant 

source, each endpoint is assumed to reprcsent the centcr of a 

two·dimensional Gaussian probability field describing the 

possible location of the pollutant cloud. Beginning at griddcd 

intervals within each probability field. the cloud is allowed to 

diffuse at rates dictated by long-range diffusion theory (Gifford. 

1982]. The probability of material impact wilhin each grid 

square is the product of each trajectory's probability of 

occurrence and the corresponding normalized pollutant 

concentration, integrated over thc entire ensemble of 

trajcctories. The result is an esLimate of thc spatial extent of 

material impact from the pollution source. 

The confidence that may be placed in this estimate is 

detennined by integrating the material impact probability field 

over the "truc" impact area. The lrue area is determined by 

applying atmospheric diffusion about the analytical trajectory 

only, and is necessarily smaller than the estimated impact area. 

3. RESULTS 

The confidencc model was applied with variations in grid 

spacing l:J.h and large-scale eddy diffusivity K. A refercnce 

experiment (run 1) was conducted with 6h = 80 km. a common 

value used in regional air quality models [National Research 

Counci/.1983]. and K= 5 x 10"' 

m2 S·I, an average value deduced from empirical tropospheric 

diffusion data {Gifford, 1977]. Subsequent experiments are 

compared with the reference experiment to determinc sensitivity 

to Lhese model parameters. 

Results of thc simulations are presented in Table 1. The 

average confidence for the reference experiment, run 1. was 

77%. This means that the estimate of downwind material 

impact will account for the fate of only 77% of thc pollutant 

emitted at the source, and that 23% of the material will be 

incorrectly placed outside the actual impact area. 

The model is inherently sensitive to grid spacing because thc 

trajectory probability distributions and pollutant conccntrations 

are assumed to be uniform within each grid square. As a result. 

runs 2·4 (Table 1) were designed to investigate the effccts of 

variable grid spacing on the calculations. Two distinct effects 

related to grid spacing arc apparent. The first is that for 

transport times of I day or less, larger grid spacing resultcd in 

greater accuracy in estinlated impact areas. It is easier to 

accurately locate the grid cell containing the center of a 

pollutant cloud if the grid squares are large rclative 10 the 

horizontal cloud dimensions. TIlc average confidencc values for 

runs 2. 3. and 4 were 72%. 81%, and 89%, respectively. 

Increasing 6h thcreforc has thc effcct of dccreasing the area 

incorrcctly idcntified as being subject to impact from a 

particular iXllluti0n source. It must be recognized howevcr that 

the increased confidence values for runs 3 and 4 do not 

necessarily indicate that incrcasing Ah will rcsult in a bener 

model. On the contrary. the larger grid spacing will reduce the 

modcl's ability to identify spatial gradients in pollutant 

concentration. 

The second effect of variable grid spacing is that the range of 

accuracy increases as 611 is incrcascd. TIils results from the fact 

thal the impact probability is assessed at discrete locations in 

time and space. As thc transport time increascs, the modeled 

pollutant cloud diffuses and occupies a larger area. With grid 

spacing as large as 320 km (run 4). several lime steps may be 

required before thc cloud "jumps" into an adjacent grid cell. 

The large-scale eddy diffusivity K governs the rate of 

horizontal diffusion. Barr and Gifford (1987J noted that in 

individuallong·range diffusion evcnts, K values may differ from 

the average value of 5 x 1()1 m2 S·1 reported by Gifford (I977) by 

as much as a factor of 2. Model runs 5-9 were thus designed to 

103 

Table 1. Confidence Model Rcsults for 

Transport Times of 1·5 Days 

"". Kt Confidence 

Run (km) (m2 s· 1) 

1 80 5.0 x 10' 

2 40 5.0 x to" 

3 160 5.0 x 10' 

4 320 5.0 x 10' 

5 80 2.0 x 10' 

6 80 3.0 x 10' 

7 80 4.0 x 10' 

8 80 1.0 x 1(>' 

9 80 1.5 x 1(>' 

"Horizontal grid spacing. 

tLarge-sca le eddy diffusivilY. 

2 3 4 

73 79 77 77 

68 70 74 75 

94 74 82 72 

100 90 75 93 

54 53 56 46 

52 69 69 58 

74 67 67 68 

84 91 87 90 

90 93 93 94 

5 

78 

71 

81 

88 

52 

62 

71 

89 

93 
investigate the effects of varying the large-scale eddy diffusivity 

K. In runs 5, 6, and 7, the K value used in the reference 

experiment (run 1) was scaled by factors of 0.40,0.60, and 0.80, 

respectively. In runs 8 and 9, K was scaled by factors of 2.0 and 

3.0. The results in Table I show that as K approaches the values 

of the trajectory error diffusivities K" and KJ (1.5 x 1O~ and 2.0 x 

lOS m2 S·l), the accuracy in estimated impact areas approaches 

100% as an upper limit In other words, the accuracy is limited 

as long as the spread of estimated trajectory endpoints is 

appreciably greater than the diffusive spread of material about 

the trajectories. 

4. SUM;\1ARY 

Several recent studies have demonstrated that interpolation of 

routine meteorological data introduces errors into individual 

trajectory calculations. These errors are expected to decrease 

with the use of trajectory ensembles of increasing size. In this 

paper a model is described that allows quantitative calculation of 

the confidence that may be placed in estimates of impact areas 

downwind of a pollutant source. The upper limit to this 

confidence is 75%, although considerable sensitivity to 

horizontal grid spacing and large-scale diffusivity was observed. 

Future work will focus on model verification using observed 

long-range diffusion data. 

REFERENCES 

Barr, S., and F.A. Gifford, The random force theory applied to regional 

scale tropospheric diffusion, Atmos. Environ., 2 I, 1737-174 1, 1987. 

Gifford, F., Tropospheric relative diffusion observations, J. Appl. 

Meteorol., 16, 3 11 -313,1977. 

Gifford, F.A., Horizonlal diffu sion in the atmosphere: A 

Lagrangian-dynamical theory, Atmos. Environ., 16,505-512,1982. 

Kahl, 1.0., Confidence limits on source-receptor relationsh ips detennined 

by ensemble trajectory analysis, Proceedings, 6,h Join' Conference on 

Applications of Air PolluJion Meteorology, American Meteorological 

Society, Boston, 1989. 

Kahl, J.~., and PJ. Samson, Uncertainty in trajectory calculations due to 

low resolution meteorological dala, 1. Climate Appl. Meteorol., 25, 

1816·183 1,1 986. 

National Research Council, Acid Deposition - Almospheric Processes in 

Eastern North America: A Review of Current Scientific 

Understanding, 375 pp., National Academy Press. Washington, IX, 

1983. 

Samson, PJ., and 1.L. Moody, Trajectories as two-dimensional 

probability fields, in Air Poilu/ion Modeling and its Application, Vol. 

I, edited by CO. Wispelacre, pp. 43-54, Plenum Press, New York, 

1981. 

104 
Detennining Regional Emissions of Aerosol Black Carbon in the Arctic 

JONATHAND. KAHL 

NRC Research Associate, NOANGMCC, Boulder, Colorado 80303 

A.D.A. HANSEN 

Lawrtmce Ber~ley Laboratory, Berk£ley, California 94720 

1. INTRODUCTION 

Black carbon (BC), a strong absorber of visible light, is an 

important component of the Arctic haze aerosol. When present 

in the atmosphere or deposited on the snow surface, it may lead 

to perturbations in the solar radiation balance. Estimates of the 

magnitude and geographical distribution of Be emissions are 

needed to model their effects on radiative transfer. 

Aerosol Be is introduced into the atmosphere by the 

combustion of carbonaceous fuels; however its emission 

strength is strongly dependent on the level of sophistication of 

the fuel combustion technology employed. The percentage of 

fuel carbon emitted as Be typically ranges from 0.1 % for sooty 

diesel engines to 0.0001 % for modem natural gas installations 

[Hansen el al., 1978]. Thus the distribution of BC emissions is 

not a simple function of the geographical fuel usage distribution. 

In fact, the least quantifiable sources may be the largest 

contributors to regionally averaged emissions. 

We present a method for estimating regional BC emissions in 

the Arclic iliat is ba.<ied on the synthesis of three independent 

pieces of infonnation: correlated high-resolution measurements 

of BC and COl' long-range atmospheric trajectory analyses, and 

tabulations of regional fuel consumption. Further details were 

presented by Kalil and Hansen [1989]. 

2. ME1ll0D AND RESULTS 

During spring of 1986, hourly measurements of BC and CO, 

were made at BRW. Careful screening of the data to eliminate 

periods of local contamination resulted in identification of 

seven distinct events lasting between 13 and 37 hours during 

which BC and COl increased relative to background 

concentrations. These events were interpreted as the passage 

over the station of air masses fTom distant regions impacted by 

strong fossil-fuel emissions [Hansen et al., 1989}. 

Linear regression of BC and COl measurement pairs revealed 

characteristic slopes for each event. The slopes, or BC/COl 

ratios, represent the incremental mass ratios of BC relative to 

COl' If it were possible to measure BC and COl in Lagrangian 

transit downwind of one of these point sources, with no losses 

or gains en roule of one species relative to another, the BC/COl 

ratio would be preserved from the source to the measurement 

point. Dilution due to turbulent diffusion would change the 

absolute concentrations, but the increments' ratio would remain 

unchanged and should be indicative of the source emission 

characteristics. 

When considering a regional source, i.e., combustion 

emissions over an area of about 1 ()6 kml containing many source 

types, Be/COl ratios will be indicative of the emission 

characteristics of the regional mixture of combustion effluent. If 

selective sources or sinks do not deplete one species relative to 

the other, the ratios measured at a distant location will be 

identical to those of the emined quantities at the upwind source 

region. If the source region can be located, the ratio can be 

multiplied by tabulated values of regional fuel consumption 

[Marlalld et al., 1985] to obtain emissions characteristics, since 

approximately 95% of carbonaceous fuel combustion effluent is 

CO,. 

To a first approximation, selective sources and sinks of BC 

and COl may be neglected during winter and spring transport 

across the Arctic basin [Hansen et al., 1989]. Owing that time 

of year natural combustion is lUllikely, precipitation scavenging 

is minimal, biological production of COl is largely donn ant, and 

atmosphere.ocean exchange is inhibited by widespread ice 

cover. If the advecled air mass is diluted during transport by 

polluted rather than pristine air, the ratios for each air mass will 

evolve toward a composite mean for the two air masses. Given 

a time sequence of measurements, it may still be possible to 

infer regional source emission ratios if the contributing regions 

can be located. 

We inspected isobaric back-trajectories [Harris, 1982) 

corresponding to the seven events described by Hansen el al., 

1989, and selected three cases for the present analysis. The 

selection process was quite restrictive and required that an an 

upwind source region be unambiguously identified by the 

trajectories [Kalil and Hansen, 1989]. The dates and BC/CO, 

ratios for the three cases, and the correlation of BC and CO2 

measurements are listed in Table 1. In each case there is a 

sizable degree of correlation between the two species, 

suggesting that the sampled air mass probably retained its 

combustion emissions characteristics during transport across the 

Arctic. The other four events of Hansen el al. (989} showed 

similar correlations, but their trajectories did not offer a clear 

indication of their upwind source regions. Note that the analysis 

can be applied only to clearly defmed transport events passing 

TABLE 1. Salient Features of Cases 1-3 

Date· Time· Duration BC/CO, 

Case 1986 (GMT) (hoo,,) ratio n 

1 March 27 0000 23 0.0099 0.92 

2 April 17 Q400 37 0.0077 0.62 

3 April 19 0000 19 0.0064 0.74 

Afu.r Hans~n ~'af. (1989). 

·Refers to beginning of event. 

tcorreJation coefficienl. 

105 
over the measurement station, and not to the general archive of 

background measurements. 

The source regions for the three cases are shown in Figure 1. 

Also shown are lines indicating the average transport pathways 

for each case, and the corresponding travel times from the source 

regions to BRW. The trajectories for case 1 show that the air 

sampled at BRW originated in the Taymyr Peninsula/Novaya 

Zemlya regions of the U.S.S.R. some 4-8 days earlier. The 

BC/C02 ratio for this case was 0.0099%. Trajectories for case 2 

initially tracked eastward from BRW before crossing the central 

polar basin toward the Soviet Arctic coast. After crossing the 

coast, the tracks turned westward and traversed a large sector of 

nonhern Siberia. Travel time from the indicated source area to 

BRW was 7-9 days. The BC/C02 ratio for this case was 

0.0077%. Air sampled during case no. 3 represents background 

Arctic air. The rrajectories track eastward across the Queen 

Elizabeth Islands before stalling in the cenrral polar basin 8·10 

days earlier. The BC/C02 ratio for this case was 0.0064%. 

Cases 1-3 are ordered in teons of decreasing BC/C02 ratios. 

According to Hansen et al. 1989. [their Table Il. these values are 

representative of a range of combustion I)'pes including 

automobiles, and natural gas and coal-fired power plants. The 

presence of these emission types in the Arctic is well known 

[Halter et 01., 1985]. suggesting that the assumptions discussed 

earlier may be appropriate in these cases. 

Cases 1-3 are also ordered in tenns of increasing rravel time 

from potential source regions. Case 1 involved rransport over a 

period of 4-8 days. Because carbonaceous fuel combustion 

processes release at least 95% of the fuel carbon as CO2, we can 

estimate the regional emission of aerosol black carbon by 

multiplying the BC/C02 ratio of 0.0099% by the estimates of 

total carbon consumption provided by Marland et al. [1985). 

Fig. l. Approximate upwind locations of air masses sampled at BRW, 

determined by examination of 850· and 7oo·mb isobaric backtrajectories, and corresponding travel times from the sou rces to BRW. 

Each ploued line represents an average trajectory for the ensemble: 

medium-dashed, case I; long-dashed, case 2; short-dashed, case 3. 

The results of this calculation imply annual BC emissions for the 

source region of about lOS g yrt. It should be noted that this 

represents a preliminary estimate subject to verification by 

similar analyses of an extended data base. 

Transport events such as case 1, with fairly rapid, well-defined 

flow to a region with known combustion emissions. represent 

potentially useful cases for estimating upwind Be emissions. 

This example was linked to one geographic region by its 

particular lrajectory; over a longer period, back-ttajectories from 

any observation point within the Arctic can cover a large number 

of candidate source regions. Given a longer time series (> I year) 

of correlated, high-resolution BC and CO2 measurements, 

emissions for a number of upwind regions could be mapped. In 

addition, the variability in BC/C02 ratios and in rransport times 

fTOm a particular region could be used to evaluate the statistical 

confidence that may be placed in the emissions estimates. 

The BC/C02 ratio for case 3. 0.0064%, was about two-thirds 

of the value for case 1. This type of transport event is useful for 

estimating the background levels of combustion·derived Be and 

CO2 within the polluted Arctic air mass. 

The BC/C02 ratio for case 2, 0.0077%, was midway between 

those for cases I and 3. Possible explanations include (I) that 

this ratio is characteristic of emissions from nonhern Siberia that 

differ from those of the Taymyr Peninsula region (case I), (2) 

that the sampled air initially had emission ratios similar to case 1 

but was diluted during transport with polluted air having different 

combustion emissions characteristics, and (3) that the assumption 

of no selective losses or gains may not be appropriate over this 

time scale (7-9 days), and that the decay of the BC numerator in 

the ratio may lead to a means for estimating the lifetime of BC 

aerosols in the winter and spring Arctic. When a longer time 

series of gas and aerosol measurements becomes available, 

episodes of this type may be compared with episodes similar to 

cases 1 and 3 to evaluate these hyp:>theses. 

The preliminary results reported here suggest that this 

technique is a viable means for mapping regional black carbon 

emissions at Arctic latitudes. Il is expected that the 

measurements needed to corroborate and expand these results 

will be available for at least one Arctic location within the next 

few years. 

REFERENCES 

Halter, B.C., 1.M. Harris and K.A. Rahn, A study of winter variability in 

carbon dioxide and Arctic haze aerosols at Barrow, Alaska, Almos. 

Environ., 19, 2033-2037, 1985. 

Hansen, A.D.A., W.H. Benner, and T. Novakov, A carbon and lead 

emission inventory for the greater San Francisco Bay area, 

Atmospheric Aerosol Research AMuai Reporl LBL.8696, 1977·1978, 

pp. 126-131, Lawrence Berkeley Laboratory, Berkeley, CA, 1978. 

Hansen, A.D.A., TJ. Conway, LP. Steele, B.A. Bodhaine, K.W. 

Thoning, P. Tans, and T. Novakov, Correlations amoog ccmbustion 

effluent species at Barrow, Alaska: Aerosol black carbon, carbon 

dioxide, and methane, J . Almos. Chern., in press, 1989. 

Harris, 1.M., The GMCC atmospheric trajectory program, NOAA Tech. 

Memo. ERL ARL·116, 30 pp., NOAA, Air Resources Laboratory, 

Silver Spring. MD, 1982. 

Kah l, 1.0., and A.D.A. Hansen, Determination of regional sou rces of 

aerosol black carbon in the Arctic, Geophys. Res. Ull., 16,327·330, 

1989. 

Marland, G., R.M. ROIty, and N.L Treat, CO2 from fossil fuel burning: 

Global distribt.llion of emissions. Tel/us, 378, 243-258, 1985. 

106 
The Global Precipitation Chemistry Project 

WIUJk\1 C. KEENE, KRYSTYNA GORZELSKA, A>,\'D JAMES N. GALLOWAY 

University a/Virginia, Char/oltesyjlle, Virginia 22903 

InsliluJe of Ecosystem Sludies. Cary Arboretwn, Millbrook, New York 12545 

JOHN M. MILLER 

NOAA, Air RuoUl'ces LAboratory, Silver Spring. Maryland 20910 

1. INlRODUcrrON 

Anthropogenic emissions of S02 and NOli have resulted in 

widespread acidification of precipitation and subsequent 

environmental damage in eastern North America and northern 

Europe. Of numerous research questions posed by this 

phenomenon, two are of special interest: (1) What was the 

composition of precipitation prior to the advent of fossil-fuel 

combustion? (2) To what degree does the long-distance 

transport of sulfur and nitrogen species influence Ihe composition of the remote troposphere? The GPCP was initialed in 

1979 to address these questions. Principal objectives are to 

measure the chemical composition of precipitation in remote 

areas of the world and to detcnnine major processes controlling 

measured composition. Earlier reports of the GPCP compare 

the composition of precipitation in remote and impacted regions 

[Galloway el al., 1982; 1984; 1987J; quantify the importance of, 

evaluate sources of, and intercompare measurement techniques 

for carboxylic acids in the atmosphere [Keene el al., 1983; 

1989a; Keene and Galloway, 1984a, b; 1985; 1986; 1988); 

assess factors controlling the chemical composition of precipita. 

tion at remote locations [lickeIIs el al., 1982; Church et al., 

1982; Galloway and Gaudry, 1984; Dayan el al., 1985; Lik£ns 

el al., 1987]; and present objective methods for differentiating 

seasalt and non·seasalt (nss) constituents in marine precipitation 

and aerosols [Keene el al., 1986; Hawley el al., 1988J. This 

report summarizes current research and reviews more recent 

contributions of the project. 

2. MA TERlALS Al\'D METIlODS 

Samples of precipitation were collected by event in 

scrupulously washed polyethylene containers. Inunediately 

after collection, pH was measured, samples were treated with 

CHCIl to prevent biological activity, and aliquots were 

subsequently sent to the University of Virginia for analyses for 

major organic and inorganic chemical constituents. To date, we 

have analyzed samples of precipitation collected at 14 land· 

based sites during 10 oceanic cruises. Reliable techniques to 

quantify primary amine compounds in precipitation and aerosols 

were developed to study the biogeochemical cycling of organic 

nitrogen through the troposphere. Wet...()nly samples of 

precipitation were collected by event and recovered within 2 

hours after the episode ended. Samples were immediately 

filtered (0.2 f1 Teflon) and frozen at -20'C [Gorzelska and 

Galloway, 1989a). Almospheric aerosols were collected on 

47·mm Teflon (Zefluor) filters mounted in polycarbonate 

cassettes. Sampling periods averaged 24 hours. Immediately 

after collection, filters were wetted with 300 ~L of methanol, 

extracted in three successive 5 mL aliquots of deionized water, 

and frozen at -20·C. Results indicate that these procedures are 

free of significant artifacts and stabilize organic nitrogen in 

samples for a period of 3 months. 

3. RESULTS Al\'D DISCUSSION 

3.1. AMINE COMPOm.'DS IN PRECIPITATION Al\.'D ATMOSPHERIC 

AEROSOLS 

A 1·yr data record for precipitation from central Virginia 

reveals a range in total amine nitrogen from 5 to 7000 nM. The 

highest concentrations are during the spring, and there is a 

marked seasonal cycle [Gorzelska and Galloway, 1989b]. The 

maximum contribution of amine to total nitrogen for precipitation in central Virginia is about a few percent, but if the 

observed concentrations of amine nitrogen are representative of 

those for precipitation in remote regions, organic nitrogen 

compounds may represent a significant fraction of the total wet 

deposition of nitrogen originating with natural sources. During 

July through September 1988, concentrations of amine nitrogen 

in precipitation over the North Atlantic Ocean ranged from 30 to 

800 nM and concentrations for the particulate.phase ranged 

from 0.003 to 1.614 nM-' (at STP) [Gonelska and Galloway, 

1989c]. Spatial variability was evident, higher concentrations 

typically being observed near the North American continent and 

in the vicinity of the Arctic circle. Interpretation of the data in 

conjunction with almospheric back trajectories and measurements of 222Rn suggests that the long-distance transport of 

terrestrial material and direct injection from surface sea water 

are important processes controlling concentrations of amine 

nitrogen in the marine boundary layer of the North Atlantic 

Ocean. 

107 

3.2. PROCESSES Cm .. 'TROWNG TIlE CHEM]CAL CO~1POSmON OF 

PRECIPITATION NEAR LUIANG, CmNA 

In cooperation with the Chinese Environmental Protection 

Agency and the Yunnan Province Environmental Monitoring 

Station, samples of precipitation were collected by event during 

the 1987 and 1988 wet seasons (May through October) at an 
altitude of 3270 m on the east slope of Yulong Mountain 

(27"12'N, 1000

9'E) near Lijiang, Yunnan Province, People's 

Republic of China [Keene el ai., 1989b]. Results indicate a 

volume-weighted average Ht expressed as pH of 5.1. On the 

basis of ratios of anions to H+, the maximum contributions of 

H2S04 , HCOOH. HC]. CH,COOH. and NHO, to free acidity 

were 35%, 27%, 25%, 23%, and 14%, respectively. Consistent 

anion deficits indicate that a maximum of 14% of free acidity 

was contributed by unmeasured anions. Trajectory analyses 

revealed that events associa ted with air masses originating ovcr 

eastern China were enriched in SO~, NO;, HCOOH, H+, and 

Calt relative to those originating over India. Indirect evidence 

supports the hypothesis that these differences reflect differences 

in air mass history, and the strength and relative proximity of 

anthropogenic sources. However, the ionic strength of 

precipitation at the site is low compared with that at other 

remote continental locations, suggesting that anthropogenic 

innuences, if present, are small and that natural sources for 

major chemical constituents are relatively weak. 

4. ONGOING RESEARCH 

Research efforts currently under way within the GPCP 

include the following: 

Evaluation of shipboard data to determine factors 

controlling the atmospheric chemistry of the 

equatorial Atlantic Ocean during August and 

September 1986. 

Analysis of a 15-yr data record for precipitation 

chemistry at MLO. 

Assessment of processes controlling the chemical 

composition of precipitation at Cape Point. South 

Africa. 

Measurement of the relative contribution of HCOOH 

emissions from fonnacine ants to total atmospheric 

concentrations. 

Evaluation of linkages between the cycling of Sand N 

in the remote almosphere. 

REFERENCES 

Church, T. M., 1. N. Galloway, T. D. 1ickeUs, and A. H. Knap, The 

chemistry of western Atlantic precipitation at the mid-Atlantic coast 

and on Bennuda, 1. Geophys. Res., 87, 11 ,013- 11 ,018, 1982. 

Dayan, V. , 1. M. Miller, W. C. Keene, and 1. N. Galloway, A 

meteorological analysis of precipitation chemistry data from Alaska, 

Almos. Environ., 19, 651-657,1985. 

Galloway, 1. N., and A. Gaudry, The chemistry of precipitation on 

Amsterdam Island, Indian Ocean, Almos. Environ., 18, 2649-2656, 

1984. 

GaUoway, 1. N., G. E. Likens, W. C. Keene, and 1. M. MiUer, The 

composition of precipitation in remote areas of the world, 1. 

Geophys. Res., 87, 8771- 8786, 1982. 

Galloway, 1. N., G. E. Likens, and M. E. Hawley, Acid precipitation: 

Natural versus anthropogenic compounds, Science, 226, 829-830, 

1984. 

Galloway, 1. N., D. Zhao, 1. Xiong, and G. E. Likens, Acid rain: China, 

Vnited States and a remote area, Science, 2]6,1559-1562, 1987. 

Gonelska, K., and 1. N. Galloway, Amine species in precipitation: 

CoUection-, storage-, and analytical-routine procedures, unpublished 

manuscript, University of Virginia, Charlottesville, 1989a. 

Gorz.elska, K., and 1. N. GaUoway, Contribution of organic nitrogen 

from primary amine compounds to the nitrogen budget of 

precipitation in central Virginia, unpublished manuscript, University 

of Virginia , Charlottesville, 1989b. 

Gonelska, K., and 1. N. Gal1oway, Global Change Studies: Phase 

distribution, transport and deposition of amine compounds over the 

North Atlantic Ocean, unpublished manuscript, University of 

Virginia, Charlottesville, 1989c. 

Hawley, M. E., 1. N. Galloway, and W. C. Keene, Standard error 

calculations for non-sea-salt constituents in marine precipitation, 

Waler Air Soil Pol/w., 42,87-102,1988. 

1ickeUs, T. C, A. H. Knap, T. M. Church, 1. N. GaUoway, and 1. M. 

MiJler, Acid precipitation on Bennuda, Nature, 297, 55-56, 1982. 

Keene, W. C, and 1. N. Galloway, A note on acid rain in an Ama7..0n 

rainforest, Tellus,]6B, 137-138, 1984a. 

Keene, W. C, and 1. N. GaUoway, Organic acidity in precipitation of 

North America, Almos. Environ., 18, 249 1-2497, 1984b. 

Keene, W. C., and 1. N. Galloway, Gran's titrations: Inherent errors in 

measuring the acidity of precipitation, Almos. Environ., 19, 199·202, 

1985. 

Keene, W. C., and 1. N. Galloway, Considerations regarding sources for 

fonnie and acetic acids in the troposphere, J . Geophys. Res., 91, 

14.466-14.474.1986_ 

Keene, W. C, and 1. N. Galloway, The biogeochemical cycling of 

fonnic and acetic acids th rough the troposphere: An overview of 

current understanding, Te/lus, 40B, 322-334, 1988. 

Keene, W. C., 1. N. Galloway, and D. H. Holden, 1r., Measurement of 

weak organic acidity in precipitation from remote areas of the world, 

J. Geophys. Res., 88, 5122-5 130, 1983. 

Keene, W. C, A. A. P. Pszenny, 1. N. Galloway, and M. E. Hawley, 

Sea-salt corrections and interpretation of constituent ratios in marine 

precipitation,1. Geophys. Res., 9/,6647-6658, 1986. 

Keene, W. C., R. W. Talbot, M. O. Andreae, K. Beecher, H. Berresheim, M. Castro, 1. C. Fanner, 1. N. Galloway, M. R. Hoffmann, 

S.-M. Li, 1. R. Maben, 1. W. Munger, R. B. Norton, A. A. P. 

Pszenny, H. Puxbaum, H. Westberg, and W. Winiwarter, An 

intercomparison of measurement systems for vapor and particulate 

phase concentrations of fonnic and acetic acids, J. Geophys. Res., 

94 . 6457-6471. 1989a. 

108 

Keene, W. c., G. Wu, R. S. Artz, 1. N. Galloway, 1. Liu, 1. M. Hams, 

and 1. M. Miller, Processes controlling the chemical composition of 

precipitation al a remote temperate continental site in south -central 

China, in Proceedings of the lnternalional Conferences on Global 

and Regional Environmental Atnwspheric Chemistry, edited by C 

S. Kiang, Beijing, PRe, in press, 1989b. 

Likens, G. E., W. C. Keene, 1. M. Miller, and 1. N. Galloway, The 

chemistry of precipitation from a remote, terrestrial site in Australia, 

1. Geophys. Res., 92,1 3,299-13,314,1987. 
Stratospheric Trace Gas Measurements at South Pole Station, Antarctica 

J.O. KEYS AND P.Y. JOHNSTON 

DeparlmenJ of Scientific and Industrial Research, Physics and Engineering Laboratory, Lauder, New Zealand 

1. INlRODUCTION 

Ground-based measurements of column N02 and 0). using 

the DAS technique, have been made by GMCC staff at SPO 

since 1986. They compiemcOl similar measurements that are 

also part of the New Zealand DSIR program and that arc being 

made at Arrival Heights (77.8·5, 166.7°E) and at the British 

Antarctic Survey base at Halley Bay (76-S, 27"W). 

The DAS measurement technique uses scattered sunJight in 

the zenith sky [Brewer et al., 1973]. The first measurements of 

N01 and 0] made in Antarctica in this way were at Arrival 

Heights [McKemie and Johnston, 19841 and showed movement 

of N02 to and from storage reservoirs under changing 

photochemical conditions. Interesting dynamical influences 

were also identified [Keys and Johnston, 1986]. The ability to 

examine N02 column changes with the sun at nearly constant 

zenith angle (in the short term) prompted the installation of 

sinlilar equipment at SPO. 

2 . DISCUSSION 

Trends in stratospheric column NOz amounts obtained using 

the DAS technique arc usually identified by making the 

measurements at constant solar zenith angle (SZA), commonly 

N 

, 

:, !>. 

u 

6 

ARRIVAL H[IGI ns I,)BG 

::. o· ........... ..........,...-.~, .......... ..,., ..... ..,.... ......... .,.... ....... · .... ..,...,-' .......... ..,.., ...... 1 ......... "YTTT'I 

!>o 60 10 eo 90 100 l11l 120 

§. l°l0Ulll POLE 19BG 111''''' ''' ~ !> 19"Jll,ql'"·111!l.P'hl.,:.. 

::. .... 1'"'." 

8 0 TTTTT"'.,..,.,.......,.....,..,....-,., ........... p .......... ..,.,-,-,~ ............... ~- ... . "1..,...,. • ..,...,-,-......., 

I.;!>O 60 70 80 90 1(.)0 11 0 110 

~ I~ HALL[Y OAY 198G 

0;o-.--.-.-n .... 6r.~~..,,"',~-..,..,.ii'o .... -..-.....,.,9TO··.,.,' -~ ............. -.··::O· ~o 

DAY If 

90', This is because the observed slant colwnn amount 

increases rapidly with increasing SZA. giving an enhancement 

of -20 times at SZA = 90-, because of changed path length and 

scattering conditions. 

Therefore, meaningful long-ternl trend analysis for data 

acquired at SPO, because of the unique geometry in which the 

condition thai the SZA = 90' is satisfied only at the equinoxes. 

requires that data be extrapolated to constant SZA, a process 

requiring prior knowledge of the enhancement function. It is 

this feature that qualified the usefulness of the data in the long 

lenn, although this qualification may not prove to be particularly 

restrictive. 

The extrapolaled dala show th e way in which th e loca tion 

modifies the N02 column through changed dynamical and 

photochemical effects [Keys and JohrlSton, 1988). The 

springtime increase in N02 at spa is quite fTCC from the 

wave-driven transport modulation that is seen in the lower 

latitude Arrival Heights data (Figure 1). 

A parlicularly interesting feature in the spa data is a 

quasi-diurnal variation in N02 observed near the equinox 

(Figure 2). This unexpected variation is interpreted as being the 

signature of a horizontal gradient in N02, which is seen as the 

tangent point moves around lhe site (Keys and Johnston, 1988). 

" IIRRIVAl HEIGHTS 198G 

"1 ~", ,, ~, "" 

:,,0'- ,;, ,;, 

" HALLEY OAY 1986 

" 

, 

_<>c. ".!,,!" ,,;\ !,." !\~. 

, ,.,., .. ..-..-.-,..,,...................., .... 

'" ,-, '" 

ofIP8?' 

11II1~,~In"::u'Ih. "",I'I9IP 

..-·.,,..,...,.,.,~ .. .,ro............--.-.----.-.-.-.-. 1(,0 110 leo 1<)0 JOO 

. . 

. c -, ' . - (\ .,f\, ,,o. . 

, 210 , 2~0 , 'co 280 JOO 

fig 1. Ne2 slan t column amounts (I x 1016 mol cm·1) for SZA = 90' (extrapolated for South Pole), 1986. Squares denote PM measurements. and 

asterisks denote AM measurements. 

109 
," 

"

o . 

z 

r---------------------------------------r" sou rH POLE 1987 

!;: ..... /. 

; .... :: 

.... «f :':f ~ ,l\ -' .•... .... ....... ~'~ " .' .... ; .. :; .... 

," 

" .. .: 

" w 

" 

" 'l} ~ 

~ 'l1 c:-; 

5 ", 

Fig 2. N02 slant column variations (I x 1010 mol CJn·2) at SPO near the 

autumn equinox, 1987. The dashed line is the SZA and squares are the 

NOz slant column amounts. 

Acknowledgments. We arc indebted to staff of the British Antarctic 

Survey, to NOAA/GMCC, and to the New Zealand Antarctic Division, 

for their operation of equipmen t and logistic support for the programs at 

HaUey Bay, South Pole Station, and Arrival Heights, and to the U.S. 

National Science Foundation for continued help . 

REFERENCES 

Brewer, A.W., C.T. McElroy, and J.B. Kerr, NilrOgen dioxide 

concentrations in the atmosphere, Nafure, 246,129-133,1973. 

McKenzie, R.L., and P.Y. Johnston, Springtime stratospheric NOz in 

Antarctica, Geophys. Res.uu., 11, 73·75, 1984. 

Keys, J.G., and P.Y. Johnston, Stratospheric NOz and 0) in Antarctica: 

Dynamic and chemicaUy controlled variations, Ceophys. Res. Left .• 

13,1260-1263,1986. 

Keys, J.G., and P.V. Johnston, Stratospheric column NOz measurements 

from three Antarctic sites, Proceedings. Polar Ozone Workshop, 

Snowmass, CO, May 1988, edited by A. Atkin, pp. 115·117, NASA 

CP 10014, NASA, Washington, DC, 1988. 

110 
Distribution and Mass Balance of Molecular Hydrogen in the Earth's Atmosphere 

M. A. K. KHALIL AND R. A. RASMUSSEN 

Oregon Graduate Center, Il1StiluJe 0/ Atmospheric Sciences, Bea vertoll, Oregon 97006 

1. I nRODUCTION 

Molecular hydrogen (H;> comes from the oceans, biomass 

and fossil fuel combustion. biological nitrogen fixation, 

volcanoes, and the oxidation of hydrocarbons including 

methane. It is removed from the aunosphere by reactions with 

OH in the troposphere, interactions with soils and by escaping 

from the aunosphere [see Wanzeck, 1988; Schmidt, 1974; 

Crutzen et 01.,1979; Conrad and Seiler, 1980]: 

For the last 10 years we have been taking weekly flask 

samples of air at seven sites spanning latitudes from the Arctic 

to the Antarctic (BRW; Cape Meares, Oregon; Cap:! Kumukahi 

and MLO; SMO; Cape Grim, Tasmania; and SPO). Samples 

are collected in O.8·L stainless steel flasks and sent to our 

laboratory for analysis [Rasmussen and Khalil, 1980). 

Measurements of Hl have been made since 1985. 

The behavior of Hl is different from that of most trace gases 

observed at these sites. For instance, in the southern hemisphere 

the phase of the seasonal cycle of Hz is opposite that of other 

gases such as CO [Khalil and Rasmussen, 1989]. Here we show 

that there is more Hz in the southern hemisphere than in the 

northern hemisphere; for most trace gases, particularly gases 

such as Hz that are affected by human activities, the gradient is 

opposite. The purpose of this paper is to document and explain 

the reversed gradient of Hz. We show that this behavior can be 

explained by the present estimates of the asymmetric latitudinal 

dislribuLion of the sources and sinks in the two hemispheres. 

2. LATITUDINAL DISTRIBUTION 

The results reported here are based on measurements taken at 

the six sea-level sites (i.e., excluding MLO) between October 

1985 and October 1987. We first removed !.he seasonal 

"'---------------------------------------, 

• :; 

• 50S ~ 

• 

.= 500 r 

:. 

~ 

l! 

:I: .. 9 2 t' 

T 

• 

Ii 

.. , ----------~--------~------------~--~ -1.0 -0.5 ••• .. ,I.' 

SIDO (Lr.,ltDdo) 

Fig. I . The latitudinal distribution of Hz. From right to left the site5 are 

BRW, Oregon. Hawaii, SMO, Tasmania, and SPO. Conct:ntrations are 

average values of de-seasonalized time series spanning October 

1985-0ctober 1987. The vertical bars arc 90% confidence limits. 

II! 

variations from the monthly time series of concenLrations. Then 

we calculated the average concenLration (and 90% confidence 

limits) at each site over the 2-yr period. The resulting latitudinal 

dislribution is shown in Figure 1. There is about 4% more Hz in 

the Antarctic than in the Arctic. 

3. SOURCES AND SINKS AN'D MASS BALANCE 

3.1. PROCEDURES 

To see whether this latitudinal distribution can be explained 

by !.he present understanding of the global Hz budget as 

described by Warneck (1988], we constructed a mass balance 

model. The procedure for the calculations is as follows. We 

divided the aunosphere into four equal volume regions or boxes: 

0' ·30'N (n~ northern tropics and subtropics), 30'N·90'N (n, 

northern middle and polar latitudes), O'·30'S (st), and 30'S· 

90·S (s). Next, we divided the sinks proposed by Warneck 

[1988] over these four regions and estimated the sources 

required in each of the four regions to obtain !.he measured 

aunospheric concentrations, as in Figure 1. We then considered 

whether emissions from the individual sources can be made 

consistent with the total required source in each box. Finally, 

we uSt!d the latitudinal distribution of the emissions (0 estimate 

the contribution of each source to the observed concentration of 

Hz in each box (source apportionment). 

3.2. MODEL 

The mass balance is written as 

dCldt = S + 0 C (I) 

c- = ~ C .. } k. =1 } (2) 

where C and S are (4 x 6) matrices of (calculated) concentrations C jt. and emissions Sjt. in thej-th box (j = 1. 2, 3. 4 refer to 

n, nl, sl, and s respectively) from the k-th source (one of the six 

listed in Table 1). The total concentration (which should match 

the observed concentration) is Cj the sum of the concentrations 

contributed by all the sources. H2 is almost steady state. so we 

take dCl dJ = 0; therefore 

S=-OC 

C=-o·ts 

(3) 

(4) 

where n is a (4 x 4) matrix consisting of (inverse) transport 

times and (inverse) atmospheric lifetimes in each of the boxes. 

The non-zero elements of n are 

0" = 0" = n,. = 041 = -( I ft.) 

0" = 0" = -(I/'t,) 

(5a) 

(5b) 
0" ~ (1/0.) + (110.) 

022 ~ (110,) + (1/n..) 

0" ~ (l /'t,) + (1/'t,,) 

0" ~ (1/0.) + (Itt,) 

(5c) 

(5d) 

(5e) 

(Sf) 

where 't is transport time, and in !lij' i and j = 1, 2, 3, 4 refer to 

fI, nt, st, s respectively. 

3.3. RESULTS 

We took 'to (transport time within a hemisphere) to be I.S 

months, 'tl (transport time across nt and sl, the tropical regions) 

to be 8 months. and the lifetimes to be as in Table 1 [see also 

Khalil and Rasmussen, 1983J. 

The soil sink. which is believed to be the main process for 

removing Hz is taken to be proportional to the land area in each 

of the four regions excluding the polar ice caps. The resulting 

distribution of sinks is shown in Table 1. 

The estimated emissions (fg yrl) in the four boxes are S" = 

35, S", = 23, 5J

, = 20, S, = 12 (also in Table 1). Each source is 

TABLE 1. Sources, Sinks, and Concentrations of Molecular 

Hydrogen (H,) 

n, nt, SI, s, 

30'-9O"N O' -30' N O'-3Q<>S 30' -90'S Toed 

Anthropogenic 

Biomass burning 

Oceans 

CH4,oxidation 

NMHC-oxidation 

Other 

Total sources 

Calculated total 

sources· 

Soil 

OH 

Other 

Total sinkst 

Global burdens (fg) 

From measured 

concentrations:j: 

Sources (Emissions in Tg yr'J) 

12 3 I 

5 5 4 

0 I I 

6 9 9 

9 5 4 

2 I I 

34 24 20 

35 23 20 

Sinl<s (Lifetimes in years) 

1.2 2.5 3 

23 12 12 

47 47 47 

1.2 2 2.3 

43.3 43.6 44.7 

I 17 

I 15 

2 4 

5 29 

3 21 

0 4 

12 90 

12 90 

6 2.4 

23 16 

47 47 

4.3 2 

44.9 177 

Global estimates taken from Warned [1988], which includes results 

from Schmidt [1 974), CrUlzen et al. (19791. and Conrad and Seiler 

(1980]. 

·Calculated using measured concentrations. 

tTotal sinks: _1_ ~ _1_ + _1_ + _1_ 

'twul 't.,~ 'toH 'tether 

:j:The conversion factor is: C (fg in each region - 1/4 of the atmosphere) = 0.0877 x S (wbv). 

divided among the four boxes according to distributions of 

population, industrial activity, OH, and observed distributions of 

methane and norunethane hydrocarbons. By this process the 

emissions from individual sources [Wanzeck, 1988) can be made 

consistent with the estimated total emissions in each lxix, as 

shown in Table 1. 

Using Eq. (4), we estimated the contribution of each of the 

six sources to the total concentration of Hz in each of the four 

boxes. The results are shown in Figure 2. Since the lifetimes of 

Hz in the four regions are much greater than the transport times, 

every source contributes to concentrations in each box. 

4. DISCUSSION A1'\fD CONCLUSIONS 

We have shown that there is significantly more Hz in the 

southern hemisphere than on the norLhem hemisphere. If we 

accept that the sink is mainly the Earth's land surface with small 

contributions from reactions with OH (as in Table 1), then the 

observed concentrations imply that the emissions must be 35 Tg 

yr1 in the northern half of the northern hemisphere, 23 Tg yr 1 in 

the tropical and subtropical northern hemisphere, 20 Tg yr 1 in 

the southern tropics, and 12 Tg yr1 in the far southern latitudes. 

These estimates are on fairly solid foundation, since we believe 

that the sinks are better known than the emissions from 

individual sources. We have also shown that the estimated 

emissions from each of six known sources of Hz are consistent 

with this distribution of the total sources of Hz among the four 

regions. There are, however, other combinations of emissions 

from the various sources and sinks that may also explain the 

observed latitudinal distribution. 

Our calculations show that the main cause of the higher 

concentration of Hz in the southern hemisphere compared with 

the northern hemisphere is the considerably more land surface 

area in the northern hemisphere over which H2 is removed. 

Acknowledgmenls. Samples at BRW, MLO, SMO, and SPO 

were coll ected by NOANGMCC staff. Support for this work 

was provided in part by the Biosphcrics Research Corporation 

and the Andarz Company. 

~ 600 I > 

~ c:::J Q, 

0. '00 ~ E3II 

N 400 

:t c:::J 

.3 30 0 ( "',,,( c 

o 200 c:::J 

100 c:::J 

o "---______ ---.J 

JO-90N O-JON 0-30S 0-90S 

Latitude 

Man-made 

BurnIng 

Oceans 

CH4-0xid 

NMHC-Oxid 

Other 

Fig. 2. COntributions of the various sources of H2 to the atmospheric 

concenlrations in four equal size regions of lhe atmosphere. 

112 
REFERENCES 

Conrad, R., and W. Seiler, Contribution of hydrogen producti on by 

biological nitrogen fi;c;8tion to the global hydrogen budget, J. 

GeopJlys. Res., 85, 5493-5498, 1980. 

Crutl..cn, P.l ., LE. Heidt, J.P. Krasnec, W.H. Pollok, and W. Seiler, 

Biomass burning as a source of atmospheric trace gases, CO, Hz. 

N20. NO. CHell' and COS, Nature, 282, 253-256, 1979. 

Khalil, M.A.K., and R.A. Rasmussen, Sou rces, sinks and seasonal 

cycles of atmospheric methane, J. Geophys. Res .. 88, 513 1-5 144, 

1983. 

Khalil, M.A.K., and R.A.Rasmusscn. Seasonal cycles of hydrogen and 

carbon monoxide in the polar regions: Opposite phase relationships, 

Ant. J. U. S. , 23(5), 177-178, 1989. 

Rasmussen, R.A., and M.A.K. Khalil, Atmospheric haloca rboos: 

Measurements and analyses of selected trace gases, in Proceedings 

0/ the NA'fO Adyanced Study Institute on Atmospheric Ozone: lis 

Variations and Hwnan Influences, ediled by A.C. Aikin, Depa. of 

Transportalion, Washinglon, DC, 1980. 

Schmidt, U. , Molecular hydrogen in Lhe atmosphere, Tel/us, 26, 78-90, 

1974 (Errata, T,I/us, 27, 93-94, 1975). 

Wameck, P., The Chemistry of tile Natlua t Atmosphere, Academi c 

Press, N.Y., 1988. 

113 
Radioactivity in the Surface Air at BRW, MLO, SMO, and SPO 

RICHARD LARSEN Al''D COLIN SAh'DERSON 

u.s. Department o!Enugy, Environ/7lefIJal Measurem.ents Laboralory, New York, New York 10014-3621 

1. II\'1RODUCIlON 

Air filter samples are routinely collected by GMCC 

personnel at BRW, MLO, SMO, and SPO for the SASP. The 

primary objective of this program is to study the temporal and 

spatial distribution of specific natural and manufactured 

radionuclides in the surface air. Two naturally occurring 

radioisotopes, 7Be and 210Pb. are continually detectable in the 

atmosphere. 7Be (half-life 53.2 days) is produced by cosmic-ray 

interactions in the upper troposphere and the stratosphere. llOPb 

(half-life 2 1 years) is a decay product of 122Rn. which is a 

natural radioisotope emilted from soils. Because of their 

distinctly different source regions, these nuclides serve as 

excellent tracers for upper and lower tropospheric sources and 

transport processes. 

2. MATERIALS AA'D METIIODS 

High-volume air filter samples are continually coUected on a 

weekly basis using Microdon filter material. The air samplers 

move -1500 mJ of air per day through a 20-cm-diamctCT filter. 

The weekly ftIter samples col1ected at BRW and MLO are 

analyzed by compressing a section of 111c filler into a 1-2 em) 

cylinder, which is analyzed by gamma-ray spectrometry using a 

high-purity germanium (HPGe) detector wiLh a 1.5-cm-diameter 

well. For each site, sections of the weekly filter samples are 

added to form a monthly composite sample. These composite 

samples are compressed into a 45-cm) plastic planchet, and are 

analyzed for gamma-ray-emitting nuclides using either HPGe 

n-type low-energy coaxial, or Ge(Li) or HPGe p-typc coaxial 

high resolution germaniwn detectors. Detailed information on 

SASP is periodically published [Feely er al. , 1988J. 

3. RESULTS 

Table I presents the long-term mean monthly surface air 

concentrations of 7Be and 210Pb at BRW, MLO, SMO, and 

SPO. Table 2 presents the surface air concentrations of 7Be 

and 210Pb in weekly filter samples col1ec ted at BRW and MLO 

during 1988. Table 3 presents the surface air concenlJalions 

of 1J3e and 2lOPb in monthly composite filter samples from spa 

and 7Be monthly concentrations from SMO, during 1988. 

4. DISCUSSION 

There were no announced atmospheric nuclear weapons tests 

or oilier significant releases of radioactive materials into the 

atmosphere during 1988, and the concentrations of fission 

products such as 95Zr, 137Cs, and 144CC were below the lower 

limits of detection by the techniques that we currently use to 

measure them. 

The weekly concentrations of 1J3e and 210Pb at BRW and 

MLO continue to show week-to-week variations superimposed 

on a seasonal cycle. Elevated '7Be at MLO during the periods 

from 210Pb source regions. The monthly concentrations of 7Be 

measured at SPO and SMO during 1988 continue to follow the 

long-term trends, but the concentrations measured at SPO are 

significantly lower than those previously reported. 

The long-term monthly mean concentrations of '7Be continue 

to show a seasonal cycle at all GMCC sites, and 2lOPb has a 

seasonal cycle at BRW and MLO. 

TABLE 1. Long-Term Monthly Mean Concentrations (fCi m·'; ±ls) oPBe at BRW, MLO, SMO, 

and SPO, and "oPb at BRW, MLO, and SPO 

'Be 210Pb 

Month BRW MLO SMO SPO BRW MLO SPO 

66± 19 (12) 228 ± 56 (18) 59 ±24 (12) I64±38 (18) 24<7 (7) 8±5 (II) I ± I (10) 

Feb. 64±20 (13) 196±51 (19) 57 ± 14 (12) 144< 59 (12) 21 ±9 (8) 9±3 (12) I ± I (8) 

March 72±20 (12) 221 ± 44 (17) 54± 12 (12) 139±61 (15) 21 ±9 (7) II ±3 (10) I ± I (8) 

April 74 ± 19 (II) 205 ± 47 (16) 48 ± II (12) 101 ±35 (14) 18 ±6 (6) 14±5 (10) I ± I (7) 

May 55 ± 10 (13) 207±40 (17) 65 ± 18 (13) 108 ±72 (15) 9 ±3 (7) 16±7 (9) I ± I (8) 

June 26±7 (13) 222 ± 37 (17) 77 ±25 (13) 77±29 (17) 3 ± I (8) 13 ±4 (10) I ± I (8) 

July 24 ±7 (12) 21O±38 (16) 89 ± 17 (13) 90±37 (16) H I (8) 1O±3 (10) I ± I (7) 

Aug. 19 ±6 (II) 19H48 (17) 86±23 (12) 81 ±28 (18) 2± 1 (7) 9 ±2 (II) I ± I (8) 

Sept. 27±5 (14) 183 ± 50 (17) 89± 16 (12) 88±27 (18) 4<2 (8) 8±3 (II) I ± I (9) 

Oct. 4J± 13 (14) 179 ± 33 (18) 78±20 (12) 97±21 (19) 9 ±3 (9) 9 ±4 (12) I ± I (9) 

Nov. 56± 16 (13) 155 ± 52 (18) 78±30 (13) 137± 38 (17) 15 ±8 (8) 7 ±3 (13) 2±2 (9) 

Dec. 52±20 (12) 206 ± 55 (18) 58± 16 (12) 163 ± 49 (17) 22±1O (7) 7 ±3 (I I) 2± I ( 9) 

Mean 48±23 (150) 200±50 (208) 70±24 (148) 115 ±52 (196) 12 ±1O (90) 10 ±5 (130) I ± I (100) 

The number of data points used to calculate each value is given in pareniheses. 

114 
TABLE 2. Weekly Surface Air Concentrations (rei mol) oPBe and 210Pb at BRW and MLO During 1988 

Sampling Interval, 1988 'Be 2iOPb Sampling Interval, 1988 'Be 210Pb 

BRIV 

Dec. 29*-Jan. 4 43 6 June 8-June 13 65 5 

Jan. 4-1an. 13 38 4 lune I3-Junc 28 9 I 

Jan. 13-1an. 20 70 24 June 28-1uly 14 36 3 

Jan. 20-Jan. 25 49 28 July I 4-July 19 17 3 

Jan. 25-Feb. 1 62 27 Juiy I 9-Aug. 2 18 2 

Feb. I-Feb. 8 57 II Aug. 2-Aug. 10 19 2 

Feb. 8-Fcb. 17 21 20 Aug. 100Aug. 17 8 

Feb. 17-Fcb.22 54 16 Aug. 17-Aug.26 8 I 

Feb. 22-March 4 40 10 Aug. 26-Aug. 30 18 2 

March 4-March 8 55 12 Aug. 3D-Sept. 6 31 3 

March 8-March 15 59 17 Sept. 6-Scpl. 13 16 2 

March I5-March 21 69 23 Scpt. 13-Scpt. 21 8 I 

March 21-~arch 29 68 24 Sept. 21-Scpt. 29 15 2 

March 29-March 31 73 28 Sept. 29--Ocl. 6 24 4 

March 31-April5 46 21 Oct. 6-0ct. 12 17 4 

April 5-April II 70 22 Oct. 12--OCL 20 26 6 

April II-April 18 68 7 Oct. 20-Nov. 1 31 5 

April 18-April 26 80 13 Nov. I-Nov. 9 40 14 

April 26-May 3 59 7 Nov. 9-Nov. 22 32 13 

YJay 3-May 10 41 13 Nov. 22-Nov, 30 71 24 

May 100May 19 59 6 Nov. 30-Dcc. 6 38 25 

May 19-.'Ifay 24 44 3 Dec. 6-- Dec. 26 

May 24-June 8 19 I 

MW 

Dec. 31·-Jan. 8 459 8 July I- July 9 163 7 

Jan. 8-Jan. IS 253 7 July 9-July IS 226 12 

Jan. IS-Jan. 22 255 5 July 15-July 22 220 9 

Jan. 22-Feb. I 346 10 July 22-Aug. I 188 7 

Feb. 1- Dec. 8 483 12 Aug. i-Aug. 8 III 4 

Feb. 8-Feb. 16 241 8 Aug. 8-Aug. 15 III 3 

Feb. 16--Feb. 22 250 13 Aug. I5-Aug. 22 207 4 

Feb. 22-March 2 176 10 Aug. 22-SepL I 231 7 

.'Ifarch 2-.'Ifarch 8 193 II Sept. I-Sept. 8 91 4 

March 8-March 15 246 16 Sept. 8-Sept. 15 19 28 

March IS-March 22 222 12 Sept. IS-Sept. 22 276 6 

March 22-April I 196 10 Sept. 22-Sepl. 30 141 3 

April I-April 8 21 1 10 Sept. 30-0cl. 7 262 7 

April 8-April IS 257 13 OCI. 7-0cl. 14 283 13 

April IS-April 22 282 18 Oct. 14-Qcl. 2 1 192 5 

April 22-April 30 161 13 OCI. 2 1-Nov. 2 247 II 

April 30-May 6 205 13 Nov. 2-Nov. 9 134 6 

May 6--May 13 114 6 Nov. 9-Nov. 16 224 6 

May 13-May 21 248 18 Nov. 16--Nov. 23 246 5 

May 21-June I 245 18 Nov. 23 -Dec. 1 274 6 

June I-June 8 428 18 Dec. I-Dec. 8 193 7 

June 8-June 17 125 6 Dec. 8-Dec. 15 100 3 

1,2,3 17-Junc 22 485 21 Dec. 15- Dec. 23 124 3 

June 22-July 1 101 6 Dec. 23-Dec. 30 167 4 

·1987. 

115 
TABLE 3. Monthly Surface Air Concentrations (fCi m')) Acknowledgment. We wish 10 thank the KOAA/GMCC Slaff al BRW, 

of 7Be at SMO and SPO, and 2iOPb at spa During 1988 MLO, SMO, and SPO for the collection of air ruter samples for the 

SASP. ' Be 210pb 'Be 210pb 

:\'!onth SMO SPO SPO Month SMO SPO SPO REFERENCES 

Jan. 37 88 <1 July 80 31 Feely, H.W., R.J. Larsen, and e.G. Sanderson, Annual report of the 

pcb. 73 106 I Aug. 65 35 <I surface air sampling program, EML.497, 165 pp., U.S. DOE 

:\'larch 68 86 Sept. 70 39 <I Environmental Measurements Laboratory, New York, 1988. 

April 28 53 <1 OcL 77 71 I 

).1ay 45 34 <I Nov. 46 100 I 

June 47 38 I Dec. 48 92 I 

11 6 
Tropospheric Radiocarbon at Amundsen-Scott South Pole Station, Antarctica, 

from 1972 to 1987 

LESTER MACHTA 

NOAA, Air Resources Laboratory. Silver Spring, Maryland 20910 

GOTE OSTLUND 

University a/Miami, Miami, Florida 33/49 

KIRBY HANSON 

NOAA, Air Resources LaboroLOry, Miami, Florida 33149 

It is generally assumed that for several thousand years prior 

(0 1950, an approximate equilibrium existed between the 

production of 10le by cosmic rays in the atmosphere and the 

natural decay associated with lhe 14(: half-life of 5730 years. 

Another recent source of production of 14(: is from fusion bomb 

tests in the atmosphere, especially those conducted during the 

1950s and the more massive tests in 1961-1962, which 

perturbed the natural equilibrium. Most of the atmospheric 14C 

exists mainly as, 14C02 [Eisenbud, 1987). Nuclear reactors also 

release some tole. 

In collaboration with NSF. Division of Polar Programs. 

NOANGMCC collected whole air samples at the Amundsen~ 

Scott SPO station since 1964 for the purpose of measuring 

aUll0sphcric 14C in CO2, The samples taken between 1964 and 

1968 were collected in cooperation with the NWS. analyzed by 

the Argonne National Laboratory, and reported in the DOE. 

Health and Safety Laboratory report, lIASL-243 [Telegadas. 

1971]. Subsequent 1

4

C measurements for 1972-1987. analyzed 

in Miami. are reported here. 

From 1972 to 1987, 6-day whole air samples were collected 

in stainless steel. 14.7-L spheres pressuriLed to 21 MPa in order 

to obtain CO2 a1iquots. Extraction of the CO2 was made prior to 

the shipment to Mianli. Nine liter-almS of CO2 gas arc required 

to fill the 14(: counting tubes for precision 14C counting. Since 

Illost aliquots contained only about 1 L of CO2, it was necessary 

to combine the discrete samples provided. Corrections for the 

measured 13C isotopic composition of the sample were made, 

and the units of the reported va1ues are the per mil (a14C) 

dev iation from the NIST standard, which was age corrected to 

the year 1950. (Earlier SPO data, 1964~1968, were corrected in 

the same fash ion.) Further details of the laboratory analyses are 

not within the scope of this report but can be obtained by 

writing the second author. 

The 14C measurements in per mil for SPO arc shown in 

Figure 1. along with measurements for 1963-1980 from northern 

Norway (Nydal and Lovseth, 1983J; all values arc on the sca1e 

(aI4C). Also see Levin et al. [1985]. A few of the new spa 

values that are obviously erroneous were omitted. The 

remaining 1972~1987 values depict a smooth. decreasing trend 

despite the 2.5~year break. Norway values arc higher than those 

at SPO. One must note that the Soviet high-yield nuclear tests 

1200 

1000 

'0 000 

0 

"-

~ 600 

• :. u .0. ....... <! -.. zoo 

0 

1060 1965 10"0 19'/5 I!JUO 19U5 

Yw 

Fig. I. t,14C conccntrations. The solid line shows conccnlraliOIlS at 

Nordkapp , Norway (7 1'N, 24'E) IN)da1 and Losvelh, 19831. alll.l the 

circl es show concentralions at SPO. The circles ahcr 1972 arc Ihc 

newly prescnled values in this paper. those before 1968 werc published 

previously. 

at Novaya Zemlya were a major source of 14C. However it is 

likely that most of the bomb test 14C in both high northern and 

equatorial latitudes. as well as the cosmogenic 14C, was initially 

injected into the stratosphere. Hence the small difrerence 

between the north polar and south polar ground-level concenlra~ 

tions might be expected at steady state. 

The main sink ror CO2 is the oceans. ahhhugh some of it 

later returns to the air. If in the future anthropogenic sources 

of 14(: remain small. it is expec ted that over the centuries. 

spa 14e readings will decrease toward the assumed pre-nuclea r 

bomb era value of zero per mil, yet will remain somewhat 

higher. 

REFERE:-.'CES 

Eisenbud, Y1., Environmi!nlai Radioactivity, 3rd Ed., 475 pp., Academic 

Press, :\ew York, 1987. 

Levin, I., B. Kromer, I L Schoch-fischer. M. Bruns. M. Munnich, D. 

Bcrdau, J. Vogel, and K. Ylunnich, 25 years of troposphcric l.:e 

observa tions in central Europe. Radiocarbon , 27. 1,19. 1985. 

Nydal, R., and K. LQvseth, Tracing bomb lole in the almosphere 

1962,1980, J. Geophys. Res., 88, 3621-3642, 1983. 

Tclcgadas. K .• The seasonal aunospheric dislribUlion and invcnlorics of 

excess carbon-14 from March 1955 to July 1989. flASL.243, pp. 

1-2-1-86. DOE Health and SafclY Laboralory. New York, 197 1. 

117 
Seasonal and Latitudinal Trends in the 13C/12C Ratio of Methane 

PAUL D. QUAY, STAGG L. KING, D. O. WILBUR, A.,'m 1. STUTZ\1AN 

University o/Washing/on, School of Oceanography WB-JO. Sea life, Washington 98195 

1. I NTRODUCTION 

Part of the recent research on atmospheric methane (CH4 ) 

lIses the isotopic comp:>sition of CH4 to distinguish between 

various CH4 sources (e.g. Stevens and Engelkemeir, 1988; Quay 

el ai., 1988]. A biogcnically produced CH4 from natural gas 

and biomass burning sources has a distinctly higher 13Cf11C than 

docs CH4 biogenica11y produced primarily fyom rice paddies, 

we tlands. and ruminants. Our research has focused on 

measuring the seasonal and latitudinal trends in the lJC[l2C ratio 

of CH4 (IJCH4 ). We intend to use the measured trends in 13CH4 

to constrain the spatial and temporal variations in abiogenic and 

biogenic CH4 source strengths. 

2, SAMPLING A.,\1D A..'IALYSIS 

In 1986, we initiated an atmospheric sample collection 

program for I3CH4 measurements at BRW and on the 

Washinglon coast. In 1987, we expanded our sample collection 

to include MLO. We send a pre-evacuated 35-L fl ask to the 

sampling site, where the flask is simply opened, allowed to f111 

to atmospheric pressure, and then returned to our laboratory. 

The CH4 concentration at time of collection is provided by 

; -n 

GMCC. Air samples arc collected approximately biweekly. 

CH4 in the air sample is extracted, purified, and combusted to 

CO2 under high vacuum following the procedure developed by 

Stevens and Rust [1982]. The CO2 is measured for its i3Cf12C 

using a Finnigan MAT 251 mass spectrometer. This procedure 

yields a CO2 sample volume of -30 ).11 for mass spectrometric 

analysis. 

i3C/I2C of the atmospheric CH4 is reported relative to 13Cf11C 

of a standard (POB) using the del notation (8): 

13 ) [ 13 ] OI3C(O/OO)= ~ (~) - 1 *1000 

12C sam 12C sId 

where sam is the sample and std is the standard. The precision 

of our SI3C measurement is about ±O.04%, based on standards 

analyzed over the last year. 

3. RESULTS 

The results of 13CH4 measurements at our three northern 

hemisphere sampling sites are presented in Figure 1. Three 

0 

vr~r~'JV • 

, -.. ~ , -':9 u 

~ 

· -" i= , 29-M. ,.-86 ~6- Cc t-86 1.J-I"I.u-81 1"'-JoI",,-87 .6-.) ...... -88 C!.J-O. c:-88 

; -n f 0 

• -41.2: 

, -41.4 

U 

2 

~ 

, 

, -41.6 

-41.8 

~ ~ -" • 2:9-n ... -86 IS-Oct.-eB 13-n.u-81 19-Ho,,-81 '8-.)" ... -08 2:3-C.c-eo 

-45.5 

• 0 

• 

-" 

, 

, 

, - 2 -"7.5 

u 

~ -., 

• · 29-M ... -86 u-Oct.-e6 13-M·U-87 .5-.) ....... -88 

r:ig. 1. Measured time series of S13C (%0 versus POB) of atmospheric methane a1 (top to bouom) BRW (71"N, 157"W), Olympic Peninsula (4S"N, 

12S"W), ,nd MLO (I9"N, ISS"W). 

11 8 
trends appear in these data: (1 ) a poleward decrease in I3CH4 , 

(2) a fall minimum in I3CH4 at 48·N and ?l·N, and (3) a fall to 

summer increase in 13CH4 at 48"N and 71"N, 

13CI'2C of CH4 depends on 'lCl''2C of the CH4 sources and 

the isotopic fractionation during OH oxidation of CH4 [Da vidson el al., 1987]. The poleward trend toward lower 13CH4 

values suggests that biogenic CH4 sources are relatively more 

important than abiogenic sources at higher northern latitudes_ 

The importance of biogenic CH4 input at high latitudes is 

also implied by the fall minimum in 13CH4, which is strongest at 

BRW. The fall minimum in 13CH4 is associated with peaks in 

CH4 concentration (Figure 2). The 13CH4 decrease associated 

with a CH4 increase indicates that the fan CH4 concentration 

maximum is derived from inputs of biogenically produced CH4 . 

We ca1culatcd a mean Oi3C of -64%0 for the CH4 source 

producing the concentration maximum measured in the fall. We 

directly measured the BDC of CH4 emitted from northern 

wetlands to be -64 ± 5%. [Quay et al., 1988), in good 

agreement with the ol3e of the CH4 source producing these 

fall 13CH4 minimum. 

The gradual increase in I3CH4 following the fall minimum is 

very likely the result of OH oxidation of CH4 . This 13CH4 

increase is associated with a CH4 concentration decrease. 

The I3CH4 increase occurs because 12CH4 reacts with OH at a 

rate about 1% greater than i3CH4 docs [Davidson et al., 1987]. 

4. SUMMARY 

Measurements of the I3C,tt2C of aunospheric CH4 provide 

important information on the Lrcn~Lh of CH4 sources. The 

seasonal and latitudinal trends in 13CH4 depend on the relative 

strengths of biogenic versus abiogenic CH4 input and CH4 loss 

via OH oxidation. Biogenic CH4 input. probably from wetlands, 

exerts significant controls on the seasonal CH4 cycle at high 

northern latitudes. Continued I3CH4 measurements at the 

GMCC sites should yield interannual trends in CH4 source 

strengths. 

119 

-n .• 

-t; . +-.+ ... 

I.'. 

, .. 

1. 11 

- I.'Z ! 

I.~' ! 

1. '70 

,. , " u_-:-,_. _,_. ~~,_ .. ~,_~~,,_, ~ .. ~ __ ._, ~._~~ .. ~"_,.LJ,, .. 

Fig 2. Time series of Bne (%0 versus PDB, solid line) and concentration of atmospheric CH4 (dashed line) [Po Steele, personal communicalionl at BRW. 

R EFERE:-ICES 

Davidson. I.A., C.A. Cantrell, S.C. Tyler, R.E. Shelter, R.I. Cicerone, 

and J.G. CaJvcrt, Carbon kineti c isotope effect in the reaction of CI14 

with Oil, J. Geophys. Res., 92. 2195-2199, 1987. 

Quay. P.O. , S.L King, I.M. Lansdo,,"'Il, and D.O. Wilbur, Isotopic 

composition of methane released from weLlands: Implications for the 

increase in atmospheric methane, Global 8iogeochem. Cycles, 2. 

385·398. 1988. 

Stevens, C.M., and A. Engelkemeir. Stable carbon isotopic composit ion 

of methane from some nalUra1 and anthropogenic sources, J. 

Geophys. Res., 93, 725-733. 1988. 

Stevens, C.M., and F.E. Rust, The carbon isotopic composition of 

atmospheric methane, J. Geophys. Res., 87, 4879-4882, 1982. 
Measurements of CFC-ll, CCl4 , and CH3

CCl3 in Flask 

Samples Collected at MLO and NWR 

G.c. RHODERICK 

NOliona/lnstitute o/Standards and Technology (Formerly, No/jonal Bureau o/Standards), Gaithersburg, Maryland 20899 

1. I N"IRODUCllON 

Since March 1988, U1C Gas Metrology Research Group of the 

Gas and Particulate Science Division of NIST has analyzed 

several gas samples submitted by the NOAH Group of GMCC. 

These were samples of ambient air that were collected in special 

stainless steel flasks at NWR and MLO and analyzed by NlST 

for specilied halocarbons. A GC/ECD calibrated wilh primary 

standards prepared gravimetrically at NlST was used for the 

analyses. 

2. SAMPUNG AND ANALYSIS 

The samples of ambient air that were collcctcd in special 

stainless steel nasks at NWR and MLO were shipped directly to 

NIST. In most cases, the samples were analyzed within 10 days 

after being fined. To date, eight samples from NWR and nine 

samples from MLO have been analyzed. 

A set of standards was previouly prepared in treated 

aluminum cylinders with a balance gas of pure dry nitrogen. 

The nitrogen was analyzed for trace halocarbons prior to 

preparing the standards. StaJldards were prepared at NIST using 

a method developed several years ago involving a 

microgravimetric technique, along with dilution by gravimetry, 

to obtain gas standards at the part per trillion (ppt) level. The 

concentration range of lhe standards was from 50 to 500 ppt, 

several being around 100 ppt. The standards in the set were 

intercomparcd on an HP5880 GC with an ECD. Generally, a 

wide-bore capillary colwnn was used for separation of the 

compounds. The regression plots, gravimetric concentration 

versus response, showed excellent correlation within the set of 

standards. Typically, one standard is used when analyzing a 

flask sample. However, periodically the complete set of 

standards are intercompared to assure stability of the 

halocarhons. 

During April and May 1989, two gravimetric standards were 

prepared in a balance of pure air. One of the standards was 

prepared using blended air, and the other was prepared using air 

collected in 30-L aluminum cylinders by NOAA at NWR and 

scrubbed of water and halocarbons. Both of these sources of air 

were analyzed for trace halocarbons. The reason for preparing 

standards in air is discussed later, but since that time a standard 

in air and one in nitrogen have been used when analyzing the 

flask samples. 

3. RESULTS AND DISCUSSION 

The compounds that have been consistenLly detennincd at 

N1ST in the flask samples have been CFC- I I, CCI" and 

CH)CCl). Table 1 shows the results for those flask samples 

collected in 1988 that have been analyzed. The data show a 

TABLE 1. Flask Sample Measured Concentration 

Data Collected CFC- I I (ppt) CCI, (ppt) CII,CCI, (ppt) 

Niwot Ridge 

Feb. 23, 1988 235 118 219 

March 29. 1988 256 11 8 114 

Aug. 16,1988 256 116 156 

Oct. 4.1988 262 116 169 

Dee. 6, 1988 260 120 113 

MaWlO Lea 

July 11.1988 255 113 149 

Sep<. 26,1988 253 

Dec. 12, 1988 256 128 113 

Jan. 30. 1989 235 116 151 

TABLE 2. Measured Concentration of CC14 Using Air 

Matrix Versus Nitrogen Matrix Standards 

Date Collected 

Feb. 23,1988 

March 29. 1988 

Aug. 8, 1988 

OCt. 4. 1988 

Dec.61988 

Feb. 28, 1989 

April 18. 1989 

June 6, 1989 

July I 1,1988 

Dec. 12, 1988 

Jan. 30, 1989 

Ma rch 13, 1989 

April 3, 1989 

May 2.1989 

June 15. 1989 

July3,1989 

Measured Concentration of CCI

4 

Nitrogen 

Matm. 

(ppt) 

Air 

Matm. 

(ppt) 

NiwOl Ridge 

118 

118 

116 

116 

120 

11 9 

119 

11 5 

108 

105 

Mauna Lea 

113 

128 

116 

120 

114 101 

115 104 

112 105 

116 98 

% Difference Conecled for 

(Air/Nitrogen) Difference· 

(ppt) 

9 1 

91 

89 

90 

94 

84 

101 

101 

104 

104 

108 

101 

102 

115 

104 

108 

Average = 90 % 

·Concentrations determined usi ng nitrogen matrix standards arc 

adjustcd to the air matrix standards using th e % difference fa ctor 

determined between the nitrogen and air matrix standards. 

120 
steady increase in the concentration of CFC-l1. which is 

consistent with NOAA's data. The CH)CCI) data arc misleading in that they show a decrease in concentration over time. 

However, this is probably due to contamination either in the 

sampling system or the flask themselves. Since thc same flask 

is used per site for each sampling, then the original contamination, if any, may be purged by this time. The later data are more 

consistent. The data for the CCl

4 have been very consistent.. 

having an average value over the period of sampling of about 

11 8 ppl. These concentrations were determined using standards 

with a balance gas of nitrogen. The NOAH group of NOAA/ 

GMCC has been determining CCI4 at about 105 ppt. resulting in 

differences of about 12% between NOAA and NlST. To try to 

resolve this difference, NlST prepared standards in scrubbed air 

to more closely imitate the air in the flask samples. Analyses of 

the flask samples since have been done using a standard in air 

and one in nitrogen. Table 2 shows the results of those 

analyses. Samples collected in 1989 are shown in Table 2 in 

order to calculate a correction factor for all data. The concentration of CCl4 as delcmlined against the air standard is consistently around 105 ppl. If the percent mean difference in 

concenlration of CCI4, as determined using the air versus 

nilrogen standards (90%), is appli ed to the earlier data, then the 

average concentration of CCl4 over the sampling period is 106 

ppt for NWR and 103 ppt for MLO. This same effect is seen 

with the CH)CCI); however the difference is only 8%. 

Currently I have no explanation for difference in the CCI" 

concentration using standards in an air matrix versus standards 

in a nilrogen matrix . However, the results obtained at NIST arc 

consistent with NOAA for CCI4 and the other compounds 

discussed. 

Achllowledgme1lt, Thanks go to James E. Elkins, chief of the 

NOAH Group at NOAA/GMCC, for having samples sent to 

NIST for analysis, and to Jim Butler for analyzing the scmbbed 

air. Thanks also go 10 Alan Yoshinaga of MLO and Jose 

Morales and Mark Losleben of NWR and anyone else involved 

in collecting and shipping the fla sk samples. 

REFERENCES 

121 

Bodhaine, B.A., and R.M. Rosson (Eds.), Geophysical Moni/oring Jor 

C/imn/ic Change, No. 16: SW1Untlry Report 1987, 110 pp. , NOAA 

Air Resources Laboratory, Boulder, CO, 1988. 

Rhoderick, G.c., and W. 1.. Zielinski, Jr., Preparation of accu rate 

muhicomponent gas standard s of volat ile toxic organic compounds 

in the low-pa ns-per-biUion range, Anal, Chem., 7, 2454·2460, 1989. 
The Mauna Loa Observatory Photochemistry Experiment 

B. A. RIDLEY 

NalioruJl Cenler for Atmospheric Research, P.O. Box 30(}(), Boulder. Colorado 80307 

MLOPEX was carried out at the GMCC site operated by 

NOAA on the island of Hawaii in April, May, and the flTSt week 

of June 1988. The MLOPEX participants having experiments at 

the site, the major species measured, and the instrumentation arc 

listed in Table 1. Measurements were made around the clock 

from May 1 to June 4, 1988. 

The latter part of April was used to set up extra facilities at 

the GMCC site. This included installation of four 6-7.3 m 

trail ers to house experiments, two lO-m sampling towers, and a 

PAM station provided by the Aunospheric Technology Division 

of NCAR. The director of the GMCC site also allowed us the 

use of a building next to the trailer site, one fonnerly used by 

the Atomic Energy Commission. Because of the size of the 

experiment and power requirements, local contractors installed 

additional power distribution from the transformer cage at MLO 

to the trailer site, and the Hawaii Electric Light Company 

installed a 70 KVA transformer for the duration of the 

experiment. 

The emphasis of the experiment was to examine the 

abWldances and partitioning of photochemically active species 

in the backgroWld troposphere through simultaneous 

measurements of a fairly large number of related trace species 

and over a period of time considerably longer than that available 

through aircraft studies. Furthermore, by contrasting the results 

with similar experiments in the continental United States, 

organized by NOAA/AL, we could examine the transformation 

of active species released mostly by anthropogenic activity to 

reservoir species. Thus, an emphasis was on the photochemical 

interactions of odd nitrogen and some odd hydrogen species. 

Specifically from these measurements, the photochemical 

production of ozone and estimates of hydropcroxy and organic 

peroxy radical concentrations can be estimated. Because the 

details of the photochemical transformations must be provided 

by modeling studies that require a knowledge of nonmethane 

hydrocarbon levels, a wide variety of these species were also 

measured. 

The MLO site is a natural choice for examining background 

chemistry in the northern hemisphere. Daily 5.day isentropic 

back·trajectories calculated for the program showed no contact 

with continental areas. Only 10·day trajectories calculated by J. 

T. Merril1 showed several short periods of origins from 

continental Asia or North America. The MLO site, of course, 

has been well characterized metcorologically and has a long 

history of measurements of some trace species and particulate 

matter. Furthermore, and of basic interest to our program, is the 

ability to make measurements in fTee troJX>sphcric air during 

nighttime and early morning downslope conditioru. 

Measurements during upslope conditions allowed for interesting 

observatioru of marine boWldary layer air with local island 

influences. 

Table 2 shows median levels of some of the trace species 

measured during the program. In the table, upslope data are 

defined as the data from 1100 to 1900 LST, and downslope data 

are defmed as those from 2200 to 1000 LST with the wind 

TABLE 1. Mauna Loa Observatory Photochemistry 

Experiment (MLOPEX) May l -1une4 , 1988 

Species 

CO2, CH4, CO, Ge, 

NzO, CFC's, meteorology 

Alkyl nitrates, halocarbons 

H..!'i0J• NO]. etc. 

Radon 

J(NO,) 

Peroxides, formaldehyde 

NM HCs, CO, CH4, CO2 

NO, NOz 

NO 

PAN, PPN, methylnitTate, 

local meteorology, 0) 

Air masses 

In strumentation 

On-site NDIR, Ge, meteorological instruments 

Adsorption, chromatographic analysis 

Filter samples, ion ch romatography 

Radon detector 

Actinometer, chemiluminescence, Eppley 

Enzyme fluorescence 

On·site chromatograph, can samples analyzed 

at NCAR 

NO/O) chemiluminescence + photolysis 

Au/CO converter, NO/O) chemiluminescence 

Gas chromatograph, cryogenic enrichment, 

TECO, PAM, Eppley 

Isentropic ltajectory analysis for each 

day of the program 

122 

Panicipants 

E. Robinson, P. Tans, P. Steele, S. Ohmans, G. Herbert, 

J. Elk ins··GMCC 

E. Atlas, S. Schauffler-·Texas A & M University 

B. Huebert, W. Warren··University of Rhode Island; 

R. Norton··NOAA/AL 

J. Kay--Drexel University; J. Fox·-NCAR 

R. Shetter, J. Calvert, A. McDaniel-·NCAR 

B. Heikes-·NCAR 

P. Zimmerman, J. Greenberg, L. Heidt, B. Henry 

L. Mizoue, C. Gilliland, W. Pollock, 

R. Lucb·-NCAR 

M. A. CarroU--NOAA/AL; D. ~ont7ka··CIRES; 

B. Ridley··NCAR 

G. liubier--NOAA/AL 

J. Walcga. F. Grahek, 1. Shetter, B. Ridlcy··NCAR 

C. Hahn--CIRES, NOAA/AL; 1. Merrill--NCAR 
TABLE 2. MLOPEX Median Values 

Species 

NO, pptv 

HKb). pptv 

NO). pplV 

1\'° 2, pplV 

NO, pplv· 

PAN, pplV 

!RONOz. PPlvt 

CH30N02• pplV 

PPN, pplV 

CO, ppbv 

0). ppbv 

HZOZ.PPIV 

ROOH,pplV 

I-Izea, pplV 

·Daytime values. 

All Dala 

255 

102 

26 

33 

11 

17 

3.5 

3.6 

-0 

139 

40 

1009 

144 

124 

Upslope 

236 

113 

37 

38 

12 

22 

4.9 

3.8 

0.2 

144 

34.5 

927 

145 

183 

Downslope 

263 

93 

15 

31 

10 

13 

2.6 

3.5 

-0 

136 

43.7 

1079 

145 

102 

t2-bulyl-, 2-isopcnlyJ·, 2·pcntyl·, 3-pentyl·, isopropyl-, n-butyl-, 

n-pentyl-. n-propylnitrate. 

speed being at least 1 m 5. 1. The nitric oxide data included in 

the table represent only data from daytime hours. 

At prescnt, interpretation of the data is being furthered by 

modeling groups at NCAR and the NOANAL. 

Acknowledgmen1, MLOPEX participants are very grateful to E. 

Robinson and his staff at MLO for providing help in organizing 

the experiment.. for their hospitality, and for many valuable 

discussions relating to the meteorology and character of the site. 

Without their interest and expertise, the program would not have 

been the success that it was. The experiment was supported by 

NSF through the Atmospheric Chemistry Division at NCAR and 

by NOANAL. We would also like to thank F. Fehsenfeld for 

his interest and support in organizing the experiment, C. Hahn 

for calculating the 5-day back-trajectories, and J.T. Merrill ror 

calculating the lO-day back-Lrajectories. 

123 
Nitrate and Non-Seasalt Sulfate in Aerosols at American Samoa 

DE:-'~lS L. SAVOIE A;'.;D JOSEPH M. PRosPERa 

University oj Miami, Rosenstiel School 0/ Marine and Atmospheric Science, Division of MarifU! and Atmospheric Chemistry, 

Miami, Florida 33149-1098 

1. !l\'TRODUCTION 

A major goal of our involvement in the SEAREX sampling 

program was to define more clearly the the major sources and 

and atmospheric pathways and fluxes of nitrate and non-seasalt 

(ns5) sulfate over the Pacific Ocean. This is largely 

accomplished through an eva1uation of the temporal and spatial 

variations in lhcir concentrations and an assessment of their 

relationships to other atmospheric constituents and atmospheric 

transport pathways. By providing an indication of the natural 

concentrations in marine air, the results from the sampling 

station at SMO (14' 15'5, 170'35'W) have prove<! to be 

invaluable in this effort. Concentrations of mineral aerosol and 

trace metals at SMO arc among the lowest ever recorded for the 

ncar-surface troposphere, and indicate that this region is 

minimally affected by transport of soil material and pollutants 

from the continents. The results fTOm our analyses of the these 

data were presented in several recent manuscripts: Prospero and 

Savoie [19891; Savoie and Prospero [1989]; and Savoie et al. 

1 1989a, b]. 

Week-long bulk aerosol samples were collected from onshore 

winds using 20 x 25 cm Whatman 41 filters at a now ratc of 1.1 

m3 min·l. Nitrate, sulfate, and mClhflneslllfnnate (MSA) in 

aqueous extracts of the filters were measured to within S% by 

ion chromatography, and sodiwn to within 2% by name atomic 

absorption. The measured nitrate is considered to be the sum of 

particulate nitrate and gaseous HN03, because in addition to 

aerosol, filters loaded with seasall should collec t vapor phase 

HNOl with essentially 100% efficiency. 

2. RESULTS 

For 1983 through most of 1987, the mean nitrate 

concentration at SMO was 0.116 ± 0.008. Similar mean 

concentrations were obtained at two other stations in the tropical 

South Pacific: 0.107 ± 0.011 J..1g m,3 at Funafuti, Tuvalu (8°30'S, 

179"12 'E), and 0.117 ± 0.010 at Rarotanga (21"\ 5 '5, 

lS9°4S'W). These concentrations are about a factor of 300% 

lower than those in the North Pacific and about 30% lower than 

those in the equatorial region (Figure 1). On the basis of the 

consistency of its ratio to MSA, nss sulfate at SMO has been 

attributed primarily to the oxidation of reduced sulfur gases 

emiucd from the ocean [Saltzman et aI., 19851; the geographical 

variation in the mean concentrations of these constituents is 

shown in Figure 1. 

There is evidence of a significant seasonal cycle in the nitrate 

concentration. The lowest nitrate concentrations occur during 

March, April, and May when the average is 0.080 ).Ig m·3 

(Figure 2). During September, October, and November, the 

average is about 73% higher, 0.1 38 ).Ig m·l . TIle overall 

seasonal cycle of nitrate at SMO is very similar to that of nss 

sulfate. The lowest mean concentration of nss sulfate (0.28 J-lg 

m 3) at SMO occurs during April and May. During September 

and October, the concentrations are about 60% higher (O.4S). 

Since nss sulfate at SMO is derived primarily fTom a marine 

biogenic source, the similar seasonal cycle in nitrate might 

suggest mal it originates from a biogenic source as well. 

However, there is also a significant difference betwccn the two 

seasonal cycles. During June through August, the nitrate 

60r---------------------, 

50 

60r-------------------, 

50 

60 

50 

40 

30 z 

1 20 

o 

] 10 

:g 0 

-' 

1 to V> 

20 

30 

40 

\lid .. "Y 

............... Oahu 

,,"om 

(n .... lak 

Belau 

fannlnq 

Nauru 

"""."can Sa"..aa 

Rcl"Clt .... qa 

N ... Col.dania 

Narfalk loland 

50+---~----~--~----~~ 

0.0 0.1 0.2 0.3 0.4 

Nitrate (1'9/mJ) 

40 

30 z 

1 20 

• '0 10 

.3 

:g 0 

-' 

1 10 

V> 

20 

'0 

40 

..... .., Oahu 

Cuam 

Eklau 

fonnlnq 

Narlalk Ialond 

50+----------r--------~ 

0.0 0.5 1.0 

NSS Sulfate (1'9/m3) 

40 

30 z 

1 20 

• -g 10 

a 0 

-' 

1 10 

V> 

20 

'0 

40 

50 

0.00 

~ 

Nl)rloik roland 

0.05 0.10 

Uethone~lU lfonote (}-'g/m3) 

Fig. I. Latitudinal variation in the mean concentrations of nitrate. nss sulfate, and YlSA over the Pacific Ocean. The hori7..0ntaJ bars indicate the 95% 

confidence limits for the means. 

124 
50 I n American Samoa 

E I • • 

40j " • "- •• '" c ! /\!\(\ ~ 

0 30 j c 

.5? 201 • ~ 

I 

~ 

~ 

c 

0 10 J "'''' t:.,'" :.S , 

::; '" I 

0' 

J F M A M J J A 5 0 N D 

~/ on h 

61 983 .... ' 98 4 019 8 5 . 1986 '" i 987 

Fig. 2. Compositcd seasonal cycles of nitrate, nS5 sulfate, and MSA at 

SMO. The solid lines connect the monthly mean concentrations. For 

nitrate and n 55 sulfa te, for which there arc a large number of data points, 

the dashed lines indicate the upper !lnd lower 95% confidence bounds of 

the monthly means. 

concentrations are significantly higher than during April. In 

contrast, the nss sulfate concenlrations remain low until the 

rather abrupt increase in September. The very weak correlation 

between nitrate and nss sulfate (r2 = 0.21, n = 194) further 

indicates that the major sourccs of the two constituents may not 

be directly related. However, these results do not definitively 

preclude a biogenic source. Nitrate derived from the oxidation 

of marine-derived particulate organic nitrogen compounds 

would not necessarily be strongly correlated with nss sulfate 

produced by the o;c; idation of reduced sulfur gases (especially 

125 

dimethylsulfide, DMS) emilted from the ocean. The 

geographical distribution of the nitrate concentrations in remote 

areas is certainly compatible with that of primary productivity, 

and such a source could account for the consistency of the mean 

concentrations over a broad region of the ocean. The nitrate 

concentrations are most strongly correlated with those of 210Pb 

[Graustein and Turekian, 1988}, which is derived almost 

exclusively from the radioactive decay of 222Rn emitted from 

soils. The production of NO ... by lightning, which occurs most 

frequently over the tropical regions of the continents, is a 

potential continental nitrate source that is not incompatible with 

the extremely low concentrations of trace metal pollutants at 

SMO. The active convection that is usually associated with 

lightning could be instrumental in rapidly transporting the 222Rn 

and 210Pb to higher altitudes where they as well as the NOli 

could be effectively transported over long distances. On the 

basis of the model of Crutzen and Cide/ [1983], lightning and 

stratospheric sources can readily account for the mean nitrate 

concenlrations over the equatorial and southern tropical regions 

of the Pacific Ocean. 

The seasonal cycle of 7Be measured by M. Uematsu 

(Hokkaido Tokai University, Sapporo, Japan, personal 

communication) is consistent with its upper tropospheric and 

stratospheric source with relatively low concentrations from 

January through April and then significantly higher 

concentrations from June through September. The mean 

seasonal cycle reported by Feely et al. [1988] shows a similar 

trend except that the higher concentrations extend into October 

and November. A similar cycle occurs in the average monthly 

concenrrations of ozone [Ollmans, 1981; Oltmans and KQmhyr, 

1986]. Ozone at SMO has been auributed to a stratospheric 

source, and its concentration and seasonal distribution arc well 

modeled by considering the stratosphere to be the dominant 

source [Levy el af., 1985]. Even recognizing that the variability 

in their concentrations yields considerable uncertainty in the 

monthly means for 7Be and nitrate, the nitrate cycle differs 

considerably. There is virtually no correlation between nitrate 

and 7Be (r2 = 0.08, N = 83), nor between nitrate and ozone 

concentrations (r2 = 0.03, N = 115) measured at SMO (5. 

Oltman" NOANGMCC, Boulder, Colorado, personal 

communication). As e;c;pcctcd, ozone does exhibit a significant 

correlation with 7Be (r2 = 0.32, N = 76). These results suggest 

that, contrary to the recent suggestion by Levy and Moxim 

[1 989], the stratosphere is probably not the major source for the 

NO ... precursor of nitrate over the tropical South Pacific. 

3. PLANS 

In the ncar future we plan more detailed comparisons of our 

nitrate data and the ozone data gathered at SMO by GMCC as a 

further check on the sources of both constituents. In light of the 

strong interest in the relationship ootween sulfate aerosols and 

climate, we will also be analyzing more SMO samples for MSA 

and comparing those results and our nS5 sulfate data with the 

CCN data provided by GMCC to determine the role of marine 

biogenic sources in establishing the concentrations of both 

sulfate and CCN. A major program during fall 1989 will be run 

in support of the NASA GLOBE night over the Pacific. The 
primary objective of that mission is to establish the feasibilty of 

a space-based LAWS. Our results will place the aircraft data in 

a climatological context. 

Ackllowledgments. We thank Tom Snowdon for the design and 

construction of the sampling systems, and Ruby Nccs and Fen 

Huang for their technical assistance. We also gratefully 

acknowledge the cooperation of R. Williams, D. Nelson, and the 

NOANGMCC program at SMO. This work was supported by 

National Science Foundation grants OCE-8405609, 

ATM-83 11335, and ATM-8612269 to the University of Miami, 

and ATM-8311694. 

REFERENCES 

Crutzcn, P.1., and LT. Gidel, A two-dimensional phOl:ochemical model 

of the atmosphere: 2, The tropospheric budgets of the anthropogenic 

chlorocarbons, CO, CH4, CH)C1, and the effect of various NO" 

sources on tropospheric ozone, 1. Geophys. Res., 88, 6641-6661, 

1983 . 

Feely, H.W., R.1. Larsen, and C.G. Sanderson, Annual report of the 

surface air sampling program, EML-497, 665 pp., Env ironmental 

Measurements Laboratory, Department of Energy, New York, Jilly 

1988. 

Graustein, W.c., and K.K. Turekian, SEAREX 210pb in Pacific marine 

aerosols, Tech. Rep. J, Atmospheric Geochemistry, Yale University, 

New London , CT, 1988. 

Levy, H. II, and W.1. Moxim, Simulated global distribution and 

deposition of reacti ve nitrogen emitted by fossil fuel combustion, 

Telfus, in press, 1989. 

Levy, H. II, J.D. Mahlman, W.J. Moxim, and S.c. Liu, Tropospheric 

ozone: The role of tran sport, J. Geophys. Res., 90, 3753-3772, 1985. 

Oltmans, S. 1., Surface ozone measurements in clean air, J. Geophys. 

R<S.,86,1174- 11 80, 1981. 

Oltmans, S.1., and W.O. Komhyr, Surface ozone distributions and 

variations from 1973-1984 measurements at the NOAA Geophysical 

Monitoring for Qimatic Change Baseline ObservalOries, J. Geophys. 

R<s" 9/, 5229-5236,1986. 

Prospero, 1.M., and D.L Savoie, Effect of continental sources on nitrate 

concentrations over the Pacific Ocean, Na/we , 339, 687~689, 1989. 

Saltzman, E.S., D.L. Savoie, 1.M. Prospero, and R.G. Zika, Atmospheric 

methanesulfonic acid and non-scasalt sulfate at Fanning and 

American Samoa, Geophys. Res. Left., 12, 437-440, 1985. 

Savoie, D.L., and J.M. Prospera, Comparison of oceanic and continental 

sources of non-sea-salt sulphate over the Pacific Ocean, Nature , 339, 

685-687,1989. 

Savoie, D.L., 1.M. Prospero, and E. S. Saltzman, Nitrate, non-seasah 

sulfate and methanesulfonate over the Pacific Ocean, in Chemical 

Oceanography, \lot. 10, edited by 1. P. Riley and R. Chester, 

Academic, San Diego, CA, in press, 19890. 

Savoie, D.L., I.M. Prospero, J.T. Merrill, and M. Uematsu, Nitrate in the 

atmospheric boundary layer of the tropical South Pacific: 

126 

Implications regarding sources and transport, 1. Almos. Chem., in 

press, 1989b. 
Analytical Electron Microscope Studies of Size-Segregated 

Particles From the Springtime Arctic Aerosol 

PATRICK 1. SHERIDAN 

National Research COW1ci/ Associate, NOM, GMCe, Boulder, Colorado 80303 

1. INllWDUCTION 

The marked reduction in springtime visibility over wide areas 

of the Arctic, a region once thought pristine, is now known to be 

due to the average tenfold increase in aerosol concentrations 

observed throughout the Arctic during Arctic spring. In spring 

1986, aerosol samples were collected by cascade impactor over 

the Alaskan and Canadian Arctic during the six"research flights 

of the AGASP-II field experiment. The particles in these 

samples were physically and chemically characterized on an 

individual particle basis using AEM [Sheridan and Musselman, 

1985; Sheridan, 1989a, b] . Data presented here suggest that 

different types and concenrrations of aerosols may be expected 

in the various layers of the stable springtime Arctic atmosphere. 

2. EXPERIMENTAL DETAILS 

The aircraft aerosol sampling system. thin-ftlm collection 

substrates, and sampling strategies were described in detail by 

Sheridan and Musselman [1985J and Sheridan [1989a, bJ. 

Particles were collected in the three-stage impactor directly onto 

1O-20-nm-thick Formvar films, which were supported by 

20D-mesh Cu TEM grids. Each grid was mounted in the center 

of lhe lOp surface of a collection plate. and during sampling was 

positioned directly beneath an impactor jet. 

Aerosol collection was initiated when the aircraft reached the 

desired sampling altitude or air mass, and usually lasted 15-20 

minutes. After sample collection, the exposed films were 

immediately returned to their field containers for shipment back 

to clean laboratory conditions and electron microscope analysis. 

Individual particles were analyzed using a lEOL Model 

JEM-200cX research AEM. In addition to direct, 

high-resolution viewing of single particles, electron diffraction 

was employed to identify mineral phases. The AEM is equipped 

wilh two x-ray spectrometers (EDS), which are sensitive to 

x-rays given off by atoms heavier than Be and Ne in the particle 

under electron oombardmenl. Through the use of an extensive 

library of particle standards, quantitative and semiquantitative 

estimates of the elemental composition of individual particles 

were made [Sheridan, 1986, 1989c]. 

3. RESULTS AND DISCUSSION 

The aerosol samples characterized by AEM were collected 

over a wide area of the North American Arctic. Figure 1 shows 

the coUection location for each of the 16 (A through P) impactor 

samples. Three major aerosol sample types were collected: 

tropospheric haze layer. tropospheric background, and 

stratospheric background. In addition, one sample was a 

mixture of clean stratospheric and tropospheric air. In Table 1, 

the samples are listed by type and collection altitude. The 

collection period for each sample (<20 min) was short enough to 

ensure that sampling was confined to a specific almospheric 

zone. This was checked by concurrent in-situ gas and aerosol 

measurements made by other aircraft-based instruments. 

Characteristics of the major sample types and of discrete aerosol 

samples are discussed here. 

For reasons discussed in Sheridan [1989a], absolute number 

concenlIations of atmospheric particles are difficull or 

impossible to measure using conventional cascade impactors. 

Relative particle concentrations, however. as determined from 

point counts of equal areas on different grids. arc easily 

calculated. Since the volumes for all samples were within 10% 

of each other. particle loadings on the films directly reflect 

ambient particle concentrations and may be used to determine 

whether a sample is more or less heavily loaded than another 

with particulate material. 

All aerosol samples collected within the Arctic stratosphere 

were composed predominantly of small (0.1-0.5 ~ diameter) 

liquid H2S04 droplets. Point counts perfonned on the final 

(small-particle) stages of these impactor samples showed 

panicle loadings to be in the moderate range when compared 

with the other types of samples. TIlis means. for example. that 

more particles were counted in a finite area on these films than 

equal areas of most of the background tropospheric aerosol 

samples (mostly light loadings). These same counts revealed 

that >95% of the fine particles on fmal stage films were 

composed of H2S04. The first two impactor stages in most of 

these samples colleCled larger liquid (i.e., acidic) sulfate 

droplets and some terrestrial dust in the I ~3 ~m size range. With 

few rare exceptions, anthropogenic particles with sources at the 

Earth's surface were not observed in these samples. The 

numbers of these large particles averaged approximately 3 

orders of magnitude less than those of the submicrometer H2S04 

droplets found on the final stages of each sample. Figure 2 

shows several types of particles observed in the springtime 

Arctic aerosol; some of the larger liquid H2S04 droplets from 

• 

.' , 

" D 

." 

Fig. 1. Aerosol collection locations for the 16 cascade impactor 

samples (A-P). 

127 
TABLE 1. Aerosol Type and Collection Altitude for Cascade 

Impac tor Samples Collected During AGASP-Il 

Sample 

A 

B 

C 

D 

E 

F 

G 

II 

I 

J 

K 

L 

M 

N 

o 

P 

Aerosol Type Collection Allitude (m) 

Tropospheric ha7..e layer 

Stratosphere 

Tropospheric haze layer 

Tropospheric ha7.e layer 

Stratosphere 

Stratospheric/tropospheric background 

Tropospheric background 

Stratosphere 

Tropospheric background 

Stratosphere 

Tropospheric haze layer 

Tropospheric haze layer 

Tropospheric haze layer 

Tropospheric background 

Stratosphere 

Stratosphere 

1224-1866 

7533 

1720-2931 

1109-2210 

9271 

2417-8140 

7016-7036 

6970-7559 

7484-7491 

8078 

391-1972 

2350 

5682-5859 

8111-8406 

8366 

8365 

the Arctic stratosphere are presented in Figure 2a. An x-ray 

spectrum from the particle shown by an arrow is presented in 

Figure 3a. 

One of the slralOspheric aerosol samples (sample F) was 

anomalous, in that very high loadings of terreslrial material were 

observed on all impactor stages, and relatively minor amounts of 

H2S04 and other aerosol types. Figure 2b shows aerosol 

particles from the first stage of impactor sample F. This sample 

was collected during a descent through subsiding stratospheric 

air between Fairbanks and Anchorage, AK (Herbert el ai., 

1989J. The rough morphology, supermicromeler size of some 

of the particles, and elemental compoSitIOn suggest a recent 

crustal input to this aerosol. Figure 3b shows an x-ray spectrum 

taken from particles within the indicated area in Figure 2b. 

Olher evidence, including air trajectory calculations, aircraft 

observations, and elemental analyses of the bulk ash (YOUllt et 

ai., 1987J. suggests that the aerosol collected was ash from the 

recent (9-13 days previous) eruptions of Ml. Augustine volcano 

in the eastern Aleutian Islands. 

Background tropospheric aerosol samples were quite similar 

to the "normal" stratospheric ones, with two major exceptions. 

First. particle loadings on these samples were lower by a factor 

of 2-4 than on stratospheric samples that were spatially and 

temporally closely collected. Since fine liquid H2S04 droplets 

again constituted the bulk of the aerosol, and since most of these 

samples were collected in the middle 10 upper troposphere. the 

data suggest that higher springtime concentrations of H2S04 

aerosol may be expected in the Arctic stratosphere than in the 

background Arctic troposphere. Second, more particles of other 

types were observed in these tropospheric samples, including 

many with sources at the Earth's surface. These classes of 

particles included crustal dust, marine salt, fly ash, and carbon 

soot. Counted together. these particles accounted for 

approximately one-t.hird of the supermicTometer particles 

collected in these samples. although the vasl majority (90-95%) 

of submicrometer particles on the final stages (and, thus, of all 

particles in the aerosol) were H2S04 droplets. 

Aerosol samples collected in Arctic haze layers showed the 

most variability of any group of samples. Particle loadings were 

in the light to moderate range, with the heavier loadings being 

observed on the Alaskan Arctic samples A and C. These 

samples were collected just north of the coastline over the 

1 

, • 

"," .. '. I •• ~ 

2,m 

b 

.t~.~ ~. ,. ... • 

~ected photomicrographs: (a) large H2S04 droplets collected in the Arctic lower stratosphere, showing impaction satellite morphology; (b) 

solid, angular particles collected in stratospheric air over southern Alaska; (c) haze layer aerosol particles; (d) sOOI carbon chain aggregate. The arrows 

and rectangular area are referred 10 in Figure 3. 

128 
:o~ ,---:--- --- --- --, 

o 

". 

... 

.. 

• 0 ' 1 

I on ,-- ,------- - ----, 

• 

"CO 

... 

.. " 

)tO~ 

I 'CO 

le~ O 

• OO 

0 

.coo 

". 

" 

, 

" 

" 

'" s Jt TI U'" 

,,'01 10(H' (.[v ) ' MOIO on ,. 

b 

.. " 

d 

Figure 3. Conventional and ultra-thin window (U1W) x-ray spectra of panicles in Figure 2. The Cu peaks in all spectra are artifacts caused by the grid. 

(a) Conventional spectrum of individual H2S04 droplet indicated by the arrow; (b) Conventional spectrum of rectangular area in Figure 2b; (c ) 

Conventional speClrum of the larger combustion sphere (indicated by the arrow); composition suggests coal-fired combustion; (d) UTW spectrum of 

carbonaceous chain aggregate. showing a major C peak. 

Be aufort Sea, whereas Lhe other haze samples were collected 

either well out over the ice (sample D) or off the coast near 

Alert, Northwest Territories (Samples K, L, and M). Aircraft 

CN and blP measurements agree well with the observed loadings 

on these samples, and show high particle concentrations and 

aerosol scattering during collection of samples A and C. 

All haze samples showed. a variety of particle types. On 

final-stage films, fine H2S04 droplets were the most common 

class of particles. followed by solid (NH4)2S04 particles. Other 

particle types encountered included crustal dust and 

carbonaceous particles. First- and second-stage films showed 

many types of supcnnicrometer particles. Larger. liquid H2S04 

droplets were observed, many with smaller solid panicles 

(usually crustal or carbonaceous) as cores. Anthropogenic 

particles were observed in all samples. These frequenlly 

included sphcrical coal fly ash and nonferrous smelter particles 

(rich in Cu, Zn, and Pb). Combustion soot (chain aggregate or 

spherical morphology) and noncombustion (probably organic) 

carbon particles were also observed in most samples. Figures 2c 

and 2d show two of thcse particles from major anthropogenic 

sources, and Figures 3c and 3d show corresponding x-ray 

spectra. 

These results show that different types and concentrations of 

particles were present during spring 1986 in various Arctic 

atmospheric layers. Although liquid H2S04 droplets were the 

dominant particle type observed in all Arctic aerosols, Arctic 

haze layers also contained significant concentrations of primary 

particles from anthropogenic and combustion processes 

(including soot carbon, coal fly ash and smelter-class particles). 

and solid (NH4hS04 particles. Haze samples collected off Alert 

showed lower particle concentrations than similar samples taken 

at lower latitudes in the Alaskan Arctic, and these measurements 

were corroborated with concurrent in-situ aerosol 

measurements. Lower stratospheric aerosols showed higher 

panicle (H2S04) concentrations than did similar middle- to 

upper-troposphere background samples, but contained very few 

panicles with surface sources. These data support the concept 

of a highly stable early-springtime Arctic atmosphere. 

REFERENCES 

Herbert, G.A., R.C. Schnell, H.A. Bridgman, B.A. Bodhaine, S.I. 

Oltmans, and G.E. Shaw, Meteorology and haze structure during 

AGASP-Il: Part I, Alaskan Arctic nights, 2-10 April, 1986, J. 

Armes. Chern. , 9, in press, 1989. 

Sheridan, P.J., The Use of Analytical Electron Microscopy for the 

Individual Particle Analysis of the Arctic Haze Aerosol, 281 pp., 

Ph.D. Dissertation, University of Maryland, College Park, 1986. 

Sheridan, P.I., Analytical electron microscope studies of size segregated 

particles collected during AGASP-ll, flights 201-203, J. Armes. 

Ch£rn., 9, in press, 1989a. 

Sheridan, P.I., Characterization of size segregated particles collected 

over Alaska and the Canadian High Arctic, AGASP-ll f1ighLS 

204·206, Atmos. Environ. , 23, in press, 1989b. 

Sheridan, P.J., Detennination of experimental and theoretical k·factors 

for a 200 kV analytical electron microscope. J. Electron Microsc. 

Tech., 11,41-61, 1989c. 

Sheridan, P.I., and lH. Musselman, Characterization of 

aircraft-collected particles present in the Arctic aerosol: Alaskan 

Arctic, spring 1983, Atmos. Enviren .• 19, 2159-2166, 1985. 

Yount, M.E., T.P. Miller, and B.M. Gamble, The 1986 eruptions of 

Augustine Volcano, Alaska: Hazards and effects, edited by T.D. 

Hamilton and J.P. Galloway. pp. 4-13, U.S. Geological Survey 

Circular 998, 1987. 

129 
Precipitation Chemistry at MLO: O-Ring Bias 

G. 1. STENSLAND 

Illinois State Waler Survey, Atmospheric Chemistry Su/jon, Champaign.. Illinois 61820 

1. INlRODUcrrON 

The N ADP/NTN and specifically the CAL al Illinois, have 

been doing numerous laboratory tests and data evaluations since 

about 1980 [0 assess the extent of the bias due to the O-ring in 

the lid of the collection/shipping container. No reasonable 

substitute for the O-ring has been found. because of increased 

cost per sample for possible replacements. The current lids and 

O-rings are used only one lime before disJXlsal. Washing 

methods for the lids have been improved considerably over time 

such that the O-ring bias has been minimized. Other users of 

this commonly used container could have considerably larger or 

smaller biases in their data because of washing procedures less 

rigorous than those at CAL and because of different sample 

handling procedures, respectively. 

2. METHODS 

With the cooperation of staff at MLO, extra samples have 

been collected to provide data for one more evaluation of the 

O-ring bias. The sampling procedure is as follows: 

(1) The regular sample from the NADP/NTN wet/dry 

collector at MLO is shipped 10 CAL weekly, following standard 

procedures. Since the collection inlerval is weekly, the typical 

age of the rain sample when it reaches the laboratory in Hilo is 

about 4 days. As the sample is transported from the MLO 

collection site to the Hilo laboratory, about 32 kIn, the water 

splashes in the bucket and contacts the D-ring gasket in the lid. 

The sample is shipped in the bucket to CAL (about 6400 km) 

and is about 10 days old when the chemical measurements begin 

at CAL. During shipment., the sample can again be in contact 

with the O-ring because of splashing or the sample container 

being inverted during portions of the shipping process. 

(2) At MLO an aliquot of about 100 mL is removed from 

the regular sample, placed in a plastic bottle, and shipped with 

the regular sample to CAL. The aliquot is thus identical to the 

regular sample except it is isolated from the O-ring during the 

6400 km shipment to CAL. 

(3) A third weekly sample is obtained from a separate 

weI/dry collector at MLO. This sample is isolated from the 

O-ring during the 32 km transport to Hilo and is then shipped in 

a l-L plastic container to CAL along with the regular NADPI 

NTN sample and an aliquot of the same. This third sample is 

never in contact with the O-ring. 

The pH is measured at the Hilo field laboratory and again in 

CAL. No preservatives are added to the samples, so organic 

acids will degrade during the typical 4 days before the pH is 

measured at Hila and also during the shipment to CAL. We 

assume pH change due to particle dissolution is much smaller 

than pH change due to degradation of organic acids. All three 

samples are measured at CAL for inorganic cations and anions; 

these results will be presented in a later report. 

3. RESULTS 

The results from the pH measurements arc shown in Table 1. 

Seven questions are 1isted and the mean and standard errors for 

eiLher H+ or H+ differences are listed as answers to the 

questions. The results indicate that most of the D-ring effect 

occurs during shipment from Hilo to lllinois. This could thus be 

prevented by aliquoting the samples at the field laboratory in 

Hila. The pH results in Table I indicate that the O-ring effect is 

much smaller than the natural pH change (due to degradation of 

organic acids). However, the O-ring concern is enhanced when 

changes in other ions (such as Na+ or MgH) are considered. 

Results for all the other ions arc being analyzed now that the 

data collection phase of this cooperative project has been 

completed. 

TABLE 1. On the Loss o[Hydrogen Ion [or Rain Samples 

from the MLO Site 

Question 

For J987, N = 2J Triplicates· 

Size of H+ loss in current NADP/NTN procedure? 

Size of H+ loss due 10 degradation of organic acids? 

Size of total H+loss due to D-ring 

Si7.e of H+loss due 10 O-ring in first 20 miles? 

Size of H+ loss due to O-ring in subsequent 4000 miles? 

Size of H+ loss from time zero (i.e., time rain ended) to 

day 4 (i.e., day of Hilo pI! measurement) 

For J984-J986 

What are the median pH and J-I+ at day 4 

(i.e. , Hilo value, for N = 58 samples)? 

Whal are the median pH and H+ al day 10 

(i.e. CAL value, N = 64)? 

·Mean ± standard error 

130 

Answer 

(J.tcqlbuckcl 

sample) 

9.3±2.6 

7.9 ± 2.4 

1.4 ± 0.6 

0.1 ±0.6 

1.3± 0.3 

Unknown 

4.84; 14.5 

5.15; 7. 1 
Trends of the Carbon Isotopic Composition of Atmospheric Methane 

c. M . STEVENS AND A. ENGELKEMElR 

Argonne Na/ional Laboratory, Chemistry and Chemical TUMology Divisions. Argonne, Illinois 60439 

A program of measuring the lJCf12C ratio of CH4 in 

background air samples from both hemispheres has been carried 

out at Argonne National Laboratory since 1981. The objective 

of this program is to apply the results of the temporal isotopic 

trends in both hemispheres toward understanding the causes of 

the increasing global concenlralion of atmospheric CH4• an 

important greenhouse gas [Blake and Rowland, 1988; KhaW 

and Rasmussen, 1983; Steele et al., 1987). The 13CP2C ratio of 

the atmospheric CH4 from several important natural and 

anthropogenic sources varies over a wide range of 50 per mil, 

which constrains the relative distributions of the fluxes needed 

to satisfy the average isotopic composition in the atmosphere, 

corrected for the fractionation effect of the sink mechanisms. 

Likewise the relative distributions of the changing fluxes of 

different isotopic composition are constrained by the temporal 

trend in the isotopic composition in the atmosphere. Further· 

more the very different distributions of the anthropogenic 

sources in the two hemispheres provide another conslraint for 

-46 -

-46.5 - (a) 

-47 -

detennining the causes of differences in the isotopic lrends 

between hemispheres. 

The CH4 in 34 L (STP) of background air samples is 

separated and isotopically analyzed by procedures described by 

Stevens and Rust [1982J and Stevens and Engelkemeir [1988J. 

Prior to 1983 all southern hemisphere air samples and a majority 

of those from the northern hemisphere were provided from the 

air sample bank at the Oregon Graduate Center. These samples 

were collected at loca tions remote from urban centers: regions 

of the Pacific Ocean, Samoa, Tasmania, and Antarctica, in the 

southern hemisphere, and mainly Cape Meares, Oregon, in the 

northern hemisphere. Beginning in 1983 rural northern Illinois 

was used as a more convenient site for the northern hemisphere, 

NOAA 's SMO provided most of the southern hemisphere 

samples after 1986. 

Some of the early measurements were reported by StevellS et 

al. [1985], and a brief summary of the results up to 1988 was 

presented by StevellS [1989}. Figure 1 shows the measured 

- -46 

- -46.6 

, .; .. '. - -47 . ~,. ~ 

)( . " \' . '\~' ., . • 

x xr • .r~ • ~ ____ • • vl ... .. ,' , ___ '-__ • - xx -' '. ' nO - ." • I ".. : -40 C-' 

~'<> 

-q8.5 -

-49 -

-46 I 

o C~pCl "' c~ros , OR 

• Northern rHinol . + Portage, AK 

• Greenland 

X Paclfio 

I . I I 

- -47.6 

- -46 

- -4B.5 

- -49 

-46 

1978 1979 19BO 1001 1902 1983 1964 1965 1086 1987 1966 1069 . 1990 

-46.5 - (b) , ..---'. ~'" - -46.6 . , 

~ • 

·E -47 l- • - -47 ~ 

~ x E-

-47.6 - ~x . - ° -47.6 n 

~'O 

o Samoa 

_l$c:- ...... 

· Talm2nla -46 - + SOlllh pole - -46 

II Canberra 

X Pacifio 

-46.6 I I I , .L I -4B.6 

1976 1970 10BO 1061 1062 1963 1064 1985 1966 1907 1980 1009 1990 

Year 

Figure 1. The stable carbon isotopic composition of almospheric methane, in the del \3e notalion (pe r mil), for (a) the northern hemisphere and (b) the 

southern hemisphere, from 197810 1989. 

131 
isotopic composition, in the del 13C notation. versus year from 

1978 to 1989. These results show 13CH4 increasing in both 

hemispheres, but with a greater rate of increase in the southern 

hemisphere. The objcctive of these trend measurements is to 

determine as far as is possible the trends in the fluxes of the 

isotopically different sources. natural or anthropogenic. which 

could account for the increasing concentration. The trends of 

the average isotopic composition of atmospheric CH4 in each 

hemisphere will reflect the trends of the average isotopic 

composition of the source fluxes in each hemisphere altered by 

interhemispheric exchange. The analysis of the atmospheric 

CH, isotopic trends shows that the BC of the source fluxes in 

the southern hemisphere have been increasing by an average of 

0.5 per mil per year during the past decade; in the northern 

hemisphere the trend has been slightly decreasing by an average 

of 0.1 per mil per year. The increasing trend in the southern 

hemisphere is most plausibly attributed to increasing flu xes OfH4 

from biomass burning. which is the principal anthropogenic 

source in this hemisphere. and is the most isotopically enriched 

in DC. The magnitude of the fluxes from the other isotopically 

heavy sources, losses from natural gas systems and coal mining. 

are negl igible in this hemisphere. This conclusion confinns the 

reports of rapidly increasing destruction of the tropical rain 

forest in South America in recent years. The indicated decrease 

in i3CH, in the northern hemisphere is more than can be 

accounted for by trends in the fluxes of the anthropogenic 

sources in this hemisphere. From this it is deduced that the 

flux es from the abundant natural wetlands in the subarctic 

regions, which are the most isotopically light, have been 

increasing. A trend of increasing wetlands area and fluxes could 

be caused by amplified climate warming in the arctic. indicated 

by the studies of Lachenbruch and Marshall [1988]. A detailed 

ana1ysis of these isotopic results will be given in a forthcoming 

paper. 

Ackll.owledgmenls. We gratefully acknowledge the cooperative 

efforts of Steven Ryan and Emily Wilson-Godinet of the NOAA 

SMO. and of Stephen Gibson. Austra1ian National University, 

School of Physical Sciences, Canberra. 

REFERENCES 

Blake,n.R.. and F.S. Rowland. Continuing worldwide increa se in 

tropospheric methane, 1978 to 1987, Science, 239, 1129-1131. 1988. 

Khalil. M.A.K., and R.A. Ra smussen, Sources, sinks, and seasonal 

cycles of atmospheric methane, J. Geophys. Res., 88. 5131 -5 144, 

1983. 

Lachenbruch, A.H., and B. V. Marshall. Changing climate: Geochemical evidence from pennafrost in the Alask.an Arctic. Science, 234, 

689-696, 1986. 

Steele. L.P., G. Fraser, R.A. Rasmussen, M.A.K. Khalil. TJ . Conway, 

A.l. Crawford, R.H. Gammon, K.A. ~asarie, and K.W. Thoning. 

The global distribution of methane in the troposphere , J. Almos. 

Chem. , 5,125-171, 1987. 

Stevens, CM., Atmospheric methane, Chem. Ceol .• 7 J, 11 -21, 1989. 

Stevens. C.M., and A. Engelkcmeir, The stable carbon isotopi c 

composition of methane from some natura] and anthropogenic 

sources,l. Geophys. Res., 93.725·733, 1988. 

Stevens, C.M., and F. Rust, The carbon isotopic composition of 

atmospheric methane. 1. Geophys. Res .• 87, 4879-4882, 1982. 

Stevens. C.M .. A. Engelkemcir, and R.A. Rasmussen, Causes of 

increa sing methane fluxe s based on carbon isotopic studies. WMO 

Technical Conference on Observations and measurement of 

Atmospheric Contaminants. Spec. Environ. Rep. 16. WMO 647. 

World Metcrological Organization. Geneva , Switzerland. 1985. 

132 
Monitoring for Sulfur Dioxide and Total Suspended Particulate at 

Mauna Loa Observatory 

H ENRY YEE, WILFRED CHING, AND RlCHARD SASAKI 

Hawaij Stale DeparlmenJ of Health, Honolulu, Hawaii 968/3 

502 and TSP monitoring were reinstituted for ong~tenn 

study at MLO by the State of Hawaii at the request of EPA 

Region IX. The long-term trends in 502 and TSP (lO-JlI1l 

diameter and smaller) concentrations will be studied to 

determine the factors contributing to increases observed in the 

past. Also, the study will work toward determining the 

aunospheric lifetimes of the particular gases and particulates. 

and the chem ical composition of the other particulates collected 

at the elevation of MLO. 

Table 1 shows the integrated concentrations of 24-h TSP and 

502 for samples collected at MLO in 1988. 

TABLE I. Twenry-Four Hour Concentrations afTSP (Hi-Vol, Gravimetric Melhod) and 502 

(Pararosaniline Method) at MLO 

1988 TSP ~g m") SOl JL8 m-3) 1988 TSP ~gm") SOl~g m·3) 

Jan . 10 4.0 0.0 July 8 1.I 

Jan. 22 6.9 7.8 July 14 2.2 

Feb. 3 8.8 0.0 July 20 18.5 1.6 

Feb. 15 0.7 1.4 Aug. 1 6.6 1.6 

Feb. 27 4.1 3.1 Aug. 13 5.2 0.8 

March 10 6.2 2.4 Aug. 5 5.2 0.0 

March 22 2.6 2.3 Sept. 6 10.0 0.0 

April 3 6.2 6.0 Sept. 18 Void 0.8 

April IS 13.5 0.0 Sep!.30 4. 1 1.5 

Ap ril 27 6.7 0.8 Oct. 12 3.6 2.0 

May9 8.3 0.0 OCI. 24 Void Void 

May21 5.2 0.0 Nov. 15 0.0 2.2 

June 2 Void 3.2 Nov. 17 3.6 0.8 

June 14 4.3 6.3 Nov. 29 2.5 Void 

June 26 0.4 0.8 Dec. II Void 0.0 

Dec. 29 3. 1 1.5 

133 
Sampling of Aerosols and Particles at MLO 

WILUk\1 ZOLLER, DIA.,\'E HERMAN, CAl XING YING, DE,'lSE CONNOR, 

BRUCE UNDERWOOD, AND ALLAN WU 

Un.iversity o/Washington, Seallie 98195 

1. I NlRODUCTION 

The following is an update on the continuation of sampling at 

MLO. This report falls into two parts, covering data from two 

d;ffcrcnt time spans: 1979-1985 and 1988. 

2. DATA FROM 1979 TO 1985: As, AI, Na 

The filters used to collcct the partic1es were llO-mmdiameter NucJcporc filters with O.4-Jl& pore diameters. Fillers 

were loaded into the filter holders in a Class-l 00 clean room at 

the University of Maryland. Filter packs were then placed in 

acid-washed polyethylene bags and mailed to MLO. Filters and 

filter holders were changed weekly by MLO personnel and 

shipped back to the University of Maryland for analysis. 

Sample filters were unpacked, removed from filter holders, cut 

into halves using a stainless-steel scalpel, and stored in 

ac id-washed (HNO)) polycrnylene bags in a Class-loo clean 

room. One-half was analyzed for elemental concentrations by 

INAA, using a procedure similar to rnat of Germani el al. 

r 1980]. The orner half was stored for later analysis. 

In 1979, particles were collected on a selective sampling 

system. In May 1980, rne selective sampling system was 

replaced by a wind directional controller, which samples 

according to time of day, wind speed, and wind direction (i.e., 

upslope versus downslope). Three primary components make 

up the samples: crustal, marine, and enriched. Justification for 

using Al to represent crustal (Figure I), As for enriched (Figure 

2), and Na for marine (Figure 3) can be found in Zoller el al. 

[1979]. For results on Lhe overall project (1979-1985) refer to 

Parringlon [1983J. 

3. DATA FROM 1988: SO;, NO:; 

Packaging and shipping were similar to Lhe process described 

in Section 2); however, all 1988 filters were analyzed at the 

University of Washington. Recently, blanks have been used to 

check rne clean1iness of the shipping process. Results showed 

the shipping process caused little or no contamination to filter 

packs. Gaseous sulfur and nitrogen precursors were collected 

on LiOH-treated llO-mm diameter Whaunan 541 filters. Filters 

were exposed for 7 days a1 MLO. Each rLller was cut into four 

quarters and stored in Whirl-packs. One quarter was then 

analyzed for SO: and NO; concentrations on a Dionex 

ion-chromatograph, Model QIC-standard column. (Remaining 

quarters are stored in refrigeration for other analyses and 

archival purposes.) 

The results shown in Figures 4 and 5 should not be taken as 

solid data. The results are being reported only to give the reader 

~ 

= 

• ,

, ~ 

! 

i 

8 = 

t ,~ 

,LAJ.J J 

, 

,~ 

"j 

Fig. 1. Aluminum concenlralions al MLO, February 1979-May 1985. 

" 

" 

" 

~ " , .. ~, . ' .. l~ 

~! " t 

, o. 

o. 

o . 

",,1 ' ''''' JJ, Jklt. 0' 

0 IN' 

Fig. 2. Arsenic concentrations at MLO, February 1979-May 1985. 

" 0 

,~ 

,"0 

~ 

"'0 

~ 

,~ 

~ , '" ~ 

! '" ! '" ~ 

\ . 0 

~ 

l 1 ' 0 

l~~~tIAJJIJ ~ 

~ 

" ~ 

" ' 0 

0 

Fig. 3. Sodium concentrations at MLO, February 1979-May 1985. 

134 
" 

, 

•• 

1 •. , 

;;i 

~, 

" 

•• 

" ., .c 

u 

t •• 

! ., 

. ,

. ,

.. '" '" u., .. '" .... ~" ." "- ... Fig. 4. Preliminary concentrati ons of SO; at MLO, 1988. 

a rough estimate of the MLO data. Actual volume of air 

sampled has not yet been detemlined because of a missing pump 

cal ibration curve. During the months of April and May, the 

system at MLO was inoperable. The figures are generated from 

rough data in 1988. Not all the filters for 1988 have recn 

sampled yet. The baselines for SO~ and NO; were determined 

from previous studies. A more detailed and complete report on 

SO: and NO; for 1988 at MLO will re published soon. 

REFERENCES 

Germani. M.S. , Concentrations of clements in the r\ational Oureau of 

Stan da rds bituminous and subbituminous coal standard refe rence 

materials, Anal. Chern., 52(2). 240-244, 1980. 

1:0 

... ~ ,~ 

, 

" ". ! 

• , " . ; 

, ,~ 

8 

t " ! " 

, . 

" ". u" '" u., .. .... ~. ." .., Fig. 5. Preliminary concentrations of :'\0; at MLO, 1988. 

Parrington, 1.R., The chemistry of background atmospheric particl es 

collected al Mauna Loa Observatory, Hawaii, Ph.D. thesis. Univ. of 

Washington, SeattJe, 1983. 

Zoller, W.H ., W.e. Cunningham, and N.K. Aras, Chemica l composition 

of atmospheric aerosols, in Geophysical Monitorillg for Climatic 

Change, No.8: Summary Report 1979. edited by G.A. lI erbert, pr. 

88-93, NOAA Air Resou rces Laboratory, Ooulder, CO, 1980. 

135 
11. International Activities, 1988 

Dale Gillette attended planning sessions in the U.S.S.R. for 

the Working Group vm experiment on desert dust to be 

conducted September 1989 in the Kurgan Tjube area of 

Tadzhikistan, U.S.S.R. The planning sessions took place in 

Dushanbe, Tadzhikistan. Moscow, and Leningrad. Among 

other Soviet institutions visited were the Soviet Academy of 

Sciences, the Hydrometeorological Service, the Leningrad Main 

Geophysical Observatory. and Leningrad State University. 

1. Chin, a long-time member of the MLO staff with special 

responsibilities for the CO2 instrumentation and flask sampling, 

was invited to visit the People's Republic of China in August. 

During this visit he served as a special consultant to PRe 

scientists in their program of CO2 measurements and monitoring. He also presented several lectures describing MLO CO2 

and other monitoring programs. 

During July 23-August 2, D. Wellman, L. Gun.er, and J. Ray 

traveled to Bermuda to conduct research aircraft data flights as a 

pan or .he CASE-W ATOX experiment. 

H. Sievcring toured the Bermuda Biological Station (BBS) 

and discussed the presentation and incorpJration at dry 

depJsition review into a BBS course entitled Global Challge. 

In Augusl, M. Luria altended the 1988 Quadrenllial Infernational Ozone Symposium at Cotlingen, FRC to present a paper 

entitled 'The relationship between 0 3 and H20 2: Field 

observation and model evaluation." 

During November 13-20, D. Wellman traveled to GannischPartenkirchen, FRG, to attend the ACID-MODES First Infensive 

Field Sludy Data Workshop and Planning Session. 

During October 3-7, Y. Kim traveled La Tokyo, Japan, to 

altend the 2nd lnJernational Conference on Atmospheric 

Sciences and Applications to Air Quality. 

In March. P. Tans participated in a conference in 

Washington, DC, sponsored by the National Geographic Society 

and the Egyptian Antiquities Organization. He presented the 

results of the GMCC measurements of air sampled from an 

ancient Egyptian tomb. 

In August, L. Waterman visited Midway Island and Guam, 

two Flask Network sampling sites. The flask sampling locations 

were inspected, sampling techniques were observed, and 

suggestions for improvements were made. 

J. Peterson and T. Conway attended the second Scienlific 

Application of Baseline Observations of Atmospheric Composition conference, Aspendale, Australia, November 14-17. Two 

papers concerning GMCC CO2 measurements were presented: 

"Short term variations of atmospheric carbon dioxide at the 

South Pole" and "Atmospheric CO2 concentrations during and 

following the 1987 EI Nino." Prior to the meeting a visit was 

made to the Australian Baseline Air Pollution Station at Cape 

Grim, Tasmania. 

The GMCC cooperative flask sampling network continued 

flask sampling agreements with Australia (Cape Grim); 

Barbados (Ragged Poin'); Canada (Alert and Mould Bay); 

France (Amsterdam Island); Japan (Syowa Station, Antarctica); 

Norway (Station M); and the United Kingdom (Halley Bay, 

Antarctica and South Georgia Island). 

In April. P. Steele visited the CSIRO Division of Aunospheric Research for discussions on coll aborative progranlS. 

During June an international cooperative experiment was begun 

to collect large-volume air samples at Niwot Ridge and analyze 

them for many trace species, including isotopic ratios in CO2 

and CH4 . Participants in the experiment are from CIRES, 

GMCC, DSIR. and CSIRO, with overall coordination by P. 

Stccle. 

During July, P. Steele participated in the Arctic Boundary 

Layer Expedition (ABLE-3A) sponsored by NASA as part of its 

Global Tropospheric Experiment program and carried out in the 

Alaskan Arctic. This participation involved suppl ying 

calibration gases to other participants in the study, as well as 

collecting flask air samples on several flights made in the 

vicinity of Barrow. 

In August, 1. DeLuisi traveled to Leningrad with R. Cess, R. 

Schiffer (leader), and T. VanderHaar to establish &. new section 

on Earth Radiation Budget (Section 13) under the U.S.-U.S.S.R. 

Bilateral Working Group VllI agreement. At this mcctillg data 

exchanges were proposed. An exchange of two GMCC 

radiation instruments with two similar instruments to be 

deployed for 1 year at Vostok and SPO was also proposed. Data 

for these two sites would also be exchanged. 

At the 1988 Quadrennial lnJernaJional Ozone Symposiwn 

held in GOllingen, F.R.G., 1. DcLuisi was appointed to serve as 

a member of the International Ozone Commission. He will act 

as rapporteur for Umkehr measurements. 

At the XlV InternaJional Laser Radar Conference held at San 

Candido, Italy, in June. 1. DeLuisi held a small workshop to 

assess the progress of the World Lidar Network. He also gave a 

progress repJrt at a discussion session that was held at the end 

of the conference. He had organized the network several years 

previously, following the eruption of El Chichon, to obtain 

slJatospheric aerosol data for correcting Umkehr measurements. 

The Umkehr corrected measurements were used to assess the 

drift rate of the SBUY, which turned oulto be very serious. 

136 

B. Bodhaine participated in the Twelfth InJemotional 

Conference on Atmospheric Aerosols Gila Nucleation in Vienna, 

AuslJia, and presented papers entitled "South Pole aerosol 

measurements during 1987," and "Aerosol fonnation and 

distribution in the Arctic during AGASP-Il. March-April 1986." 

As part of U.S.-U.S.S.R. Working Group XIII, B. Bodhaine 

traveled to Moscow and Dushanbe to assist in planning a desert 

dust experiment in southern U.S.S.R and to aid in plann ing a 

high-altitude continental background monitoring sta tion ncar 

Dushanbe. 

In August 1988, W. Komhyr, R. Evans. R. Grass, S. 

Oltmans, P. Franchois, and G. Koenig attended the 1988 

Quadrenniallnlernationai Ozone Symposium held in Goningen, 

West Gennany. 

S. Oltmans visited Tudor Hill, Bennuda, in October 1988, to 

begin a program for monitoring tropospheric ozone as part of 

the Atmosphere/Ocean Chemistry Experiment (AEROCE). 

R. Grass, R. Evans, and K. Leonard participated in an 

intercomparison of Dobson ozone speclJophotometers in Perth, 
Australia, in November. En route, Grass and Evans visited 

personnel of the Australian Weather Bureau in Melbourne to 

discuss Dobson instrument calibrations. Prior to returning to 

Boulder in December, Grass and Evans visited New Zealand to 

calibrate an automated Dobson spectrophotometer located in 

Lauder. 

In addition to the Australian and New Zealand Dobson 

instrument calibrations, two instruments from the U.S.S.R. were 

calibrated in Boulder during 1988. 

1. Elkins attended the SABOAC·il meeting in Aspendale, 

Australia, on November 11 · 19, 1988. 

1. Buller attended the SAGA-ll workshop to review the 

cruise data with American and Soviet scientists in Seattle, 

Washington, March 2-3, 1988. 

1. BUller presented a paper entilled "Atmospheric distributions, deep-water profiles, and surface flux es of NzO from the 

Soviet-American Gas and Aerosol Ex periment of 1987 (SAGA 

II)" at the Commonwealth Scientific and Industrial Research 

Organization (CSIRO), Aspendale, Australia, 1988. 

137 
12. Publications and Presentations by GMCC Staff, 1988 

Artz. R.S .• G.D. Rolph, and I.M. Hams, Meteorological summary of 

four W ATOX 1985 research intensives. Almos. Environ., 22, 

2361-2369. 1988_ 

Barrie. L.A., l .W. Bouenheim, R.C. SchneU, P.1. Crutzen. and R. A. 

Rasmussen, Ozone destruction and photochemical reactions at polar 

sunrise in the lower Arctic 8lmosphere, Nature, 334, 138- 141, 1988. 

Darry, R.G., R.C. Cianflone, W.M. Miles, M.e. $errc7..c . and R.C. 

Schnell, Surface characteristics of Arctic sea ice from remote 

sensing data, Prepriflls. IGS Symposiwn on Ice Dynamics, Hobart, 

Tasmania, February 1988, 

l3oalman, J.F., M. Luria, e.c. Van Valin, and D.L Wellman, 

Continuou s atmospheric sulfur gas mea suremen ts aboard an aircraft: 

A comparison between the flame photometri c and fluorescence 

methods, A/mos. Environ .• 22(9), 1949- 1955, 1988. 

Boatman,l.F., D.L. WeUman, R.C. Schnell, K.M. Busness, M. Luria, 

and c.c. Van Valin, In-night intercomparisons of some aircraft 

meteorological and chemical measurement technique s, Global 

Biogeochem . Cycles, 2(1), I-ll, 1988. 

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

ClimaIic Change, No. 16: SWTII7ItJry ReporI 1987. 110 pp .. NOAA 

Air Resources Laboratory, Boulder, CO, 1988. 

Bodhaine. B.A., E.G. Dutton. ].1. DeLuisi, ] .M. Harris. G.E. Shaw, 

A.D.A. Hansen, and T. Novakov, South Pole aerosol measurements 

during 1987. PuprinIs, 12th International Conference on 

Almospheric Aerosols and Nuclealion, Vienna. Austria, August 

22-27. 1988. 

Bridgman. H.A .. H. Sievering, and T. Watson. Large and giant aerosols 

in the marine boundary layer during WATOX, lanuary 4·9, 1986. 

Global Biogeochem. Cycles, 2(1),13 -21,1988. 

Bridgman, H.A., R.C. Schnell. B.A. Bodhaine, and S.1. Oltmans. 

Aerosol and ozone distributions over the westem Nonh ALiantic 

during W ATOX-86. Global Biogeochem. Cycles, 2(1),23-39, 1988. 

Burkhardt, M.R., M.P. Buhr, ].D. Ray. and D.I-I. Stedman, A continuous 

monitor for nitric acid, Almos. Environ., 22, 1575- 1578, 1988. 

Butler, J.H., Atmospheric distributions, deep-water profiles, and surface 

nuxes of NzO from the Soviet-American Gas and Aerosol 

Experiment of 1987 (SAGA D), paper presented at the Commonwealth Scientific and Industrial Research Organization (CSIRO), 

Aspcndale, Australia, 1988. 

Buller, J.lI., Trace gas mea surements in the air and waters of the 

western Pacifi c and eastern Indian Oceans during SAGA D, paper 

presented at the College of Oceanography, Oregon State University , 

1988_ 

Buller, l.H., lE. Pequegnat, L.1. Gordon, and R.D. Jones, Cycling of 

methane. carbon monoxide, nitrous oxide , and hydroxylamine in a 

meromictic, coastal lagoon, UtUlJr. Coast. Shelf Sci., 27, 181 -203, 

1988_ 

Butler, J.H., J.W. Elkins, C.M. Brunson, K.B. Egan, T.M. Thompson, 

T.1. Conway, and B.D. Hall, Trace gases in and over the west PaciJic 

and cast Indian Oceans during the EI Nino-Sou thern Oscillation 

event of 1987, NOM DaIa Reporl ERL ARL· J6, 104 pp., NOAA Air 

Resou rces Laboratory, Boulder, CO, 1988. 

Conway, T.1., and K.W. Thoning, Short-term variations of atmospheric 

carbon dioxide at the South Pole, paper presented at the Second 

Scientific Application of Baseline Observations of Atmospheric 

Composition Conference, Aspcndale, Australia, November 14- 17, 

1988_ 

Conway, T.J., P. Tans, L.S. Waterman, K.W. Thoning, K.A. Masarie, 

and R.H. Gammon, Atmospheric carbon dioxide measurements in 

the remote global troposphere, 1981-1984, Teltus, 40B, 81· 115, 

1988. 

Elkins, lW., T.M. Thompson, and J.H. Buller, Halocarbons CFC- 12 and 

CFC-l l , and nitrous oxide measurements from NOAA/GMCC 

baseline observatories since 1977, paper pre sented at the Second 

Scientific Application of Baseline Observations of Atmosphe ric 

Composition Conference, Aspendale, Australi a, November 14-17, 

1988_ 

Evans, R.D., G.L Koenig, W.O. Komnyr, J. Easson, and P Marche., 

Umkehr observations at five automated Dobson spectrophotometer 

stations in 1986 and 1987, paper presented at the Quadrennial Ozone 

Symposium, Gcuingen, FRG, August 8- 13, 1988. 

Franchois, P.R., G. Koenig, R.D. Evans, and W.D. Komhyr, Compari· 

son of ECC ozonesonde and Umkehr profile at Boulder, Colorado, 

1985- 1987, and Mauna Loa, Hawaii, 1985-1987, paper presented at 

the Quadrennial Ozone Symposium, GOltingen, FRG, August 8- 13, 

1988_ 

Fried, A, R. Sams, W. Dorko, J.W. Elkins, and l-1. Cai. Determination 

of nitrogen dioxide in air compressed gas mixtures by quantitative 

tunabl e diode laser absorption spectrometry and chemiluminescence 

detection, Anal. Chem., 60, 394-403, 1988. 

Fryrear, D.W., ]. E. Stout, and D. A. Gilleue, Instrumentation for wind 

erosion, Proceedings, 1988 \vind Erosion Conference, Lubbock, 

TX, April!!-13, 1988, pp. 11 7-132, Texas Tech. Univ., 1988. 

Galloway, J.N., R.S. AriZ, U. Dayan, R.F. Pueschel, and ].F. Boatman, 

W ATOX 85: An aircraft and grOlmd sampling program to detennine 

\Tanspon of trace gases and aerosols across the Western ALiantic 

Ocean, Atmos. En viron., 22( J 1),2345-2360, 1988. 

Gillette, D.A., Estimation of dust production by wind e rosion, for use by 

the National Acid Precipitation Assessment Program, Proceedings, 

1988 \Vind Erosion Conference, Lubbock, TX , April 11 -13, 1988, 

pp. 188- 197, Texas Tech. Un iv., 1988. 

Gillette, D.A. , Threshold friction velocities for dust production for 

ag ricultural soils, J. Geophys. Res., 93,12,645-12,662,1988. 

Gillette, D.A., and R. Passi, Modeling du st emission caused by wind 

erosion, 1. Geophys. Res., 93, 14.233-14,242,1988. 

Grass, R.D., and W.O. Komhyr, Travelling standa rd lamp cali bration 

checks of Dobson ozone spcctrophotometers during 1985- 1987, 

paper presented at the Quadrennia l Ozone Symposium, GOllingen, 

FRG, August 8-13. 1988. 

Haltcr, B.C., ].M. Harris, and TJ. Conway, Component signals in the 

record of atmospheric carbon dioxide concentration at Amcrican 

Samoa,}. Ceophys. Ru .. 93, 15,9 14-15,91 8, 1988. 

Hansen, A.D.A., B.A. Bodhaine, E. G. DUllon, and R. C. Schnell , 

Aerosol black carbon measurements at the South Pole: Initial 

results, 1986-1987, Geophys. Res. Lell .• 15, 1193- 11 96, 1988. 

Herbert , G.A ., ].M. Harris, and B.A. Bodhaine, Atmosphcric transport 

during AGASP-II: The Alaskan nights (2-10 April 1986), Almos. 

Environ., 23(11),2521 · 2536, 1988. 

Herbert, G.A., 1.M . Ham s, B.A. Bodhaine, and R.C. Schnell , A 

summary of atmospheric transport to Barrow, Alaska, during the 

Arctic Gas and Aerosol Sampling Program (March 1983 and April 

1986), Preprinls. Second Conference on Polar Meteorology and 

Oceanography, Madison, WI, March 29-31, 1988, pp. 116-11 8, 

American Meteorological Socicty, Bostoo, 1988. 

Kah l, J.D., and P.1. Samson, Some limitations of rawin sondes in 

pollutant tran sport studies, Proceedings, Symposium on Lower 

Tropospheric Profiling: Needs and Technologies, Boulder, CO, May 

3 1·June 3, 1988, pp. 67--68, American Meteorologi cal Society, 

Boston , 1988. 

Kahl, J.D., J. M. Hams, G.A. Herbert, and M.P. Olson, lntercomparison 

of three long-range trajectory models applied to Arctic haze, Teflus, 

418.524-536.1988_ 

138 

Kim, YJ., H.S. Sievering, and J.F. Boatman, Airborne measurements of 

atmospheric aerosol particles in the lower troposphere ove r the 

Centra l United States, J. Ceophys. Res .. 91(Dl0), 12 ,63 1-12,644, 

1988_ 

Komhyr, W.D., E.G. DUllon, and T.M. Thompson, A general 

gravimetric dilution technique for preparing trace calibration gases: 

NzO calibration gas preparation, Environ. Sci. Techno!., 22, 

845-848. 1988_ 

Komhyr, W.D., R.D. Grass, and R.K. Leonard. Calibration of primary 

standard Dobson spectrophOlometer no. 83 and total ozone trCflds at 

Mauna Loa Observatory, Hawaii, and American Samoa, South 

Pacifi c, paper presenled at the Quadrennial Ozone Symposium, 
Gouingen, FRG, August 8- 13, 1988. 

Komhyr, W.O., S.J. Olunans, and R.D. Grass, Atmospheric ozone at 

South Pole, Anurctica, in 1986,1. Ceophys. Res., 93(5), 5167-5184, 

1988. 

Komhyr, W.D., P.R. Franchois, S.E. Kuester, P.J. Reitelbach, and M.L. 

Fanning, Eee ozonesonde observations at South Pole, Antarctica, 

during 1987 ,NOAA Data Report ERL ARL-J5, 319 pp., NOAA Air 

Resources Laboratory, Boulder, CO, 1988. 

Komhyr, W.O., R.D. Grass, R.D. Evans, and R.K. Leonard, Results of 

international Dobson spectrophotometer and Brewer 

spectrophotometer intercomparisons, Arma, Switzerland, 1986, 

paper presented at the Quadrennial Ozone Symposium, Gouingen, 

FRG, August 8-13,1988. 

Komhyr, W.O., S.1. Olunans, R.D. Grass, P.R. Franchois, and R.K. 

Leonard, Changes in total ozone and ozone vertical distributions at 

South Pole, Antarctica, 1962-1987, paper presented at the Quadrennial Ozone Symposium, Goltingen, FRG, August 8-13, 1988. 

Komhyr, W.O., S.J. Oltmans, P.R. Franchois, W.F. Evans, and W.A. 

Matthews, The latitudinal distribution of ozone to 35 kID altitude 

from ECC ozonesonde observations, paper presented at the 

Quadrennial Ozone Symposium, GOttingen, FRG, August 8- 13, 

1988. 

Lepel, E.A., W.K. Hensley, J.F. Boaunan, K.M. Busness, W.E. Davis, 

D.E. Robenson, and W.G.N. Slinn, Airborne radioactivity 

measurements from the Chernobyl plume, 1. Radioonal. Nucl. 

C,",m., 123(1), 7- 19, 1988_ 

Luria, M.L. and J_E Meagher, Computer simulations of the boundary 

layer oxidation and removal of atmospheric poUutants over the 

Western Atlantic Ocean, Almas. Environ., 22, 307-319,1988. 

Luria, M., CC Van Valin, W.C. Keene, D.L. WeUman, J.N. Galloway, 

and J.P. Boatnlan, Eastward sulfur nux from the Nonheastern 

United States, A/mos. Environ .. 22,1847-1856,1988. 

Matthews, W.A., W.O. Komhyr, and P.R. Franchois, Vertical 

distribution and variation in atmospheric ozone over Lauder, New 

Zealand, paper presented at the Quadrennial Ozone Symposium, 

GOllingen, FRG, August 8-13, 1988. 

McPctcrs, R.O., and W.O. Komhyr, Long-tcnn changes in SBUV/ 

TOMS relative to the world primary standard Dobson instrument, 

paper presented at the Quadrennial Ozone Symposium, Gotlingen, 

FRG, August 8~13, 1988. 

Olunans, S.1., W.O. Kornhyr, P.R. Franchois, and W.A. Matthews, 

Tropospheric ozone: Variations from surface and ECC ozonesonde 

observations, paper presented at the Quadrennial Ozone Symposium, 

Gottingcn, FRG, August 8-13,1988. 

Ohmans, S.l., PJ. Sheridan, R.C. Schnell, and J.W. Winchester, 

Springtime surface 07.one nuctuations at high Arctic latitude and the 

possible relationship to atmosphe ric bromine, Preprinls, Polar 

Ozone WorksJwp, Aspen, CO, May 9-13,1988. 

Oltmans, S.1., P.l Sheridan, R.C. SchneU, R.E. Peterson, J.W. 

Winchester, L.A. Barrie, J.D. Kahl, and W.O. Komhyr, Springtime 

07..one nuctuations at high Arctic latitudes and their possible 

relationship to almospheric bromine, paper presented at the Quadrennial Ozone Symposium, Gottingen, FRG, August 8-13,1988. 

Pickeri ng, K.E., R.R. Dickerson, G.J. Huffman, l.F. Boatman, and A. 

Schanot, Trace gas transport in the vicinity of frontal con vective 

clouds,J. Ceophys. Res., 93(Dl), 759-773,1988. 

Pueschel, R.F., J.F. Boatman, and R.S. Artz, Aerosols over the western 

Atlantic: Scale heights, ooncentrations and nuxes, Almos. Environ. , 

22(1/),2371-2380,1988_ 

Rahn, K.A., D.H. Lowenthal, and J.M. Harris, Long-range transport of 

pollution aerosol from Asia and the Arctic to Okushiri Island, Japan, 

Almos. Environ., 23(1 1),2597·2608, 1988. 

Reinsel, G.R., G. C. Tiao, S.K. Ahn, M. Pugh, S. Basu, J.J. DeLuisi, 

C.L. Mateer, A.J. Miller, P.S. Connell, and OJ. Wuebbles, An 

analysis of the 7-year record of SBUV satellite ozone data: Global 

profile features and trends in total ozone, J. Ceophys. Res., 93, 

1689-1703 ,1988_ 

Robinson, E., and L. Ashman, Book Review (Acid Earlh: The Global 

Threat of Acid Pol/wion, Earthscan, 190 pp., Washington, DC, 

1985), Water Air Soil Pof/w. 37, 230-231, 1988. 

Robinson, E., B.A. Bodhaine, W.O. Komhyr, SJ. Oltmans, L.P. Steele, 

P. Tans, and T.M. Thompson, Long-term air quality monitoring at 

the South Pole by the KOAA program Geophysical Monitoring lor 

Climatic Change, Rev. Ceophys., 26, 63-80, 1988. 

Rosen, lM., D.J. Hoffman, J.R. Carpenter, l.W. Harder, and S.J. 

Oltmans, Ball00nborne Antarctic frost point measurements and their 

impact on polar stratospheric cloud theories, Geophys. Res. Lel/., IS, 

859-862, 1988. 

SchneU R.C., Arctic air chemistry, Arctic Res., 2,39-41, 1988. 

SchneU, R.C, Arctic haze: Long-range pollution of the polar atmosphere, paper presented at the Global Effects of Aunospheric 

Contaminants Meeting, University of New Mexico, Albuquerque, 

NM, October 25, 1988. 

Schnell, R.C., Bacteria produced atmospheric condensation and ice 

nuclei, PreprinJs, ACU, Chapman Conference on lhe Gaia 

Hypothesis, San Diego, CA, March 7-1 1, 1988. 

SchneU, R.C., Long-residence time, high carbon content aerosol in the 

Arctic troposphere, abstract of paper presented at the DNA Global 

Effects Meeting, Santa Barbara, CA, April 19-21, 1988. 

SchneU, R.C, J. D. Kahl, II.A. Bridgman, and G.A. Herbert, Aerosol 

formation and distribution in the Arctic during AGASP-II, in 

Atmospheric Aerosols and Nucleation, edited by P.E. Wagner and G. 

Vali, pp. 32-35, Springer-Verlag, New York , 1988. 

SchneU, R.C., J.~. Kahl, H.A. Bridgman, and G.A. Herbert, A major 

Arctic haze event nonh of Point Barrow, Alaska, April 1986, 

Preprints, Second Conference on Polar Meteorology and Oceanog· 

raphy, Madison, WI, March 28·30, 1988, pp. 112-115, American 

Meteorology Society, Boston, 1988. 

Schnell, R.C, P.J. Sheridan, R.E. Peterson, and SJ. Ollrnans, Airborne 

measurements of tropospheric ozone destruction and particulate 

bromide formation in the Arctic, Proceedings, Polar Ozone 

Workshop, Aspen, CO, May 9-13, 1988, NASA Conference 

Publication 1014, pp. 204-205, Nationa l Aeronautics and Space 

Adminisuation, Washington, DC, 1988. 

SchneU, R.C., 1.0. Kahl,I-l.A. Bridgman, G.A. Herbert, B.A. Bodhaine, 

and SJ. Ohmans, Aerosol formation and distribution in the Arctic 

during AGASP-IJ, March-April 1986, Preprinls, 12lh /nlerllQ/jonal 

Conference on Atmospheric Aerosols and Nu.cleation, Vienna, 

Austria, August, 22-27,1988. 

Tans, P.P., J.W. Elkins, D.R. Kitl-is, Air sampling procedures and 

measurements of the air composition of the second boat pilaf 

Khufu's pyramid, NOAA Tech . Memo. ERL ARL.163, 21 pp .• 

NOAA Air Resources Laboratory, Boulder, CO, 1988. 

Taylor, lA., A stochastic Lagrangian aunospheric transport model to 

determine globa l CO2 sou rces and sinks--A preliminary discussion, 

T,I/us, 418, 272-285, 1989_ 

Thompson, T.M., Results from the SAGA-ll expediti on in 1987, paper 

presented at National Bureau of Standards, Gaithersburg, MD, 1988. 

Thompson, T.M., lW. Elkins, lii. Butler, and K.B. Egan, 

Trichloronuoromethane (CFC-l l) and dichlorodifluoromelhane 

(CFC· 12) in the western Pacific and eastern Indian oceans' 

atmosphere and surface water, paper A31-07 paper presented at the 

AGU Spring Meeting, Baltimore, Maryland, May 16-20, EOS, 69, 

3 13, 1988_ 

Thoning, K.W., TJ. Conway, P.P. Tans, and JT. Peterson, Atmospheric 

COl oonccntrations during and following the 1987 EI Nino, paper 

presented at the Second Scientific Application of Baseline 

Observations of Atmospheric Composition Conference, Aspcndale, 

Australia, November 14·17, 1988. 

Van Valin, CC, and YI. Luria, OJ' CO, hydrocarbons, and dimeth)" 

sulfide over the Western Atlantic Ocean, Atmos. Environ ., 22, 

2401-2409,1988. 

Whelpdale, D.M., W.C Keene, A.D.A. Hansen, and J. Boatman, 

Aircraft measurements of sulfur, nitrogen, and carbon species during 

WATOX-86, Global Biogeochem. Cycles, 1(4), 357-368,1988. 

Wilkison, S., and J.F. Boatman, The NOAA King Air airborne data 

acquisition system: Description and user's guide, NOM Tech. 

Memo. ERL ARL-I64, 19 pp., NOAA Air Resources Laboratory, 

Silver Spring, MD, 1988. 

139 
ABLE 

ACID·MODES 

ACR 

AEC 

AEM 

AEROCE 

AES 

AFOS 

AGASP 

AL 

ALE/GAGE 

ALT 

ANARE 

AOML 

ARL 

ARM 

ASASP 

ASCS 

AQG 

BAO 

BLM 

BRW 

CAF 

CAL 

CAMS 

CASE 

CFC 

CFC·II 

CFC·12 

CGBAPS 

ClRES 

CN 

CNC 

CPACE 

CRREL 

CSI 

CSIRO/DAR 

CSU 

CURTAIN 

DAS 

DB 

DEW 

DOE 

DOl 

DOT 

DSIR 

ECC 

ECD 

EC·GC 

ECP 

EDS 

EKTO 

EML 

ENSO 

EPA 

13. Acronyms and Abbreviations 

Atmospheric Boundary Layer Expedition 

Acid Model Evaluation Studies 

active cavity radiometer 

Atomic Energy Corruuission 

analytical electron microscope 

Atmosphcrc!Ocean Chemistry Experiment 

Atmospheric Environment Service, Canada 

Automated Field Observing System 

Arctic Gas and Aerosol Sampling Program 

Aeronomy Laboratory, Boulder, Colorado (ERL) 

Atmospheric Lifetime Experiment/Global Atmospheric Gases Experiment 

Alert Observatory. Canada 

Australian National Antarctic Research Expeditions 

Atlantic Oceanographic and Meteorological Laboratory, Miami, Florida (ERL) 

Air Resources Laboratory, Silver Spring, Maryland (ERL) 

Aerosols and Radiation Monitoring Group, Boulder, Colorado (GMCC) 

Active Scattering Aerosol Spctromtcr Probe 

Alaska Soil Conservation Service 

Air Quality Group. Boulder. Colorado (GMCC) 

Boulder Atmospheric Observatory 

Bureau of Land Management 

Barrow Observatory, Barrow, Alaska (GMCC) 

Clean Air Facility 

Central Analytical Laboratory 

Control and Monitoring System 

Coordinated Air-Sea Experiment 

chlorofluorcarbon 

trichloroOuoromethane 

dichlorodiOuoromcthane 

Cape Grim Baseline Air Pollution Station, Australia 

Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, Colorado 

condensation nuclei 

condensation nucleus counter 

Central Pacific Atmospheric Chemistry Experiment 

Cold Regions Research & Engineering Laboratory, U.S. Anny, Hanover, New Hampshsire 

Columbia Scientific, Inc. 

Commonwealth Scientific and Industrial Research Organization/Division of Atmospheric Research, 

Australia 

Colorado State University 

Central United States RADM Test and Assessment Intensives 

differential absorption spectroscopy 

direct-beam {irradianccj 

distant early warning 

Department of Energy 

Department of Interior 

Department of Transportation 

Department of Scientific and Industrial Research, New Zealand 

electrochemical concentration cell 

electron capture detector 

electron caprure-gas chromatograph 

Enhanced Chemistry Project 

Energy Dispersive X-ray Spectrometry 

(a commercial name for a prefabricated building) 

Environmental Measurements Laboratory (DOE) 

E1 Nino/Southern Oscillation 

Environmental Protection Agency 

140 
ERBE 

ERL 

FAST 

FID 

FS 

mR 

GAGE 

GC 

GCE 

G.E. 

GLOBE 

GMCC 

GMD 

GOES 

GPCP 

HCFC 

HFC 

HP 

IDM 

IMPROVE 

lNAA 

JR 

ISWS 

LANDSAT 

LAWS 

LEAPS 

LES 

L1PM 

LOPC 

LST 

LW 

LWD 

LWRF 

MABIE 

MCCP 

MclDAS 

MFOV 

MLO 

MLOPEX 

MSFC 

MSL 

MUSIC 

NADP 

NAPAP 

NASA 

NBS 

NCAR 

NDIR 

NERDDC 

NESDIS 

NIH 

NIP 

NIST 

NOAA 

NOAH 

NPS 

NRBS 

NS F 

Earth Radiation Budget Experiment 

Environmental Research Laboratories. Boulder. Colorado (NOAA) 

forward alpha scattering techniques 

flame ionization detector 

Forest Service 

Fourier transform infrared (specIToscopy) 

Global Almospheric Gases Experiment 

gas chromatograph 

Global Change Expedition 

General Electric 

Global Backscatter Experiment 

Geophysical Monitoring for Climatic Change, Boulder, Colorado CARL) 

ground meteorological device 

Global Orbiting Earth Satellite 

Global Precipitation Chemistry Project 

Hydrochloroflurocarbon 

Hydrofluorocaroon 

Hewlett-Packard 

International Business Machines 

Interagency Monitoring of Protected Visual Environments (NPS, EPA, FS, BLM, and 001) 

instrumental neutron activation analysis 

infrared 

Illinois State Water Survey 

Land Satellite 

Laser Atmospheric Wind Sounder 

Low Electron Attachment Potential Species 

Lincoln Experimental Satellite [operated by Lincoln Laboratories, Lincoln, Massachusetts] 

Laser Integrating Plate Method 

laser optical particle counter 

local standard time 

long wave 

long wave downward irradiance 

longwave radiative forcing 

Mauna Loa Aerosol Backscatter Intercomparison Experiment 

Mountain Cloud Chemistry Project 

Man-computer Interactive Data Access System 

multiple field of view radiometer 

Mauna Loa Observatory, Hawaii (GMCC) 

MLO Photochemical Experiment 

Marshall Space Flight Center, Huntsville, Alabama (NASA) 

mean sea level 

Multiple Species Intercomparison 

National Atmospheric Deposition Program 

National Acid Precipitation Assessment Program 

National Aeronautics and Space Administration 

National Bureau of Standards, Boulder, Colorado (now NlST) 

National Center for Atmospheric Research, Boulder, Colorado 

non-dispersive infrared analyzer 

National Energy Research Development anf Demonstration Council, Australia 

National Environmental Satellite, Data, and Information Service (NOAAL 

National InsLirutes of Health 

normal incidence pyrheliometer 

National Institute for Standards and Technology, Boulder, Colorado (formerly NBS) 

National Oceanic and Atmospheric Administration 

Nitrous Oxide And Halocarbons Group, Boulder, Colorado (GMCC) 

National Park Service 

non-Rayleigh backscatter 

National Science Foundation 

14 1 
NTN 

NWR 

NWS 

NZARP 

OGC 

PC 

PDB 

PES A 

P.1. 

PIXE 

PMOD 

PMT 

PRC 

PSCs 

PYC 

RADM 

RITS 

RSD 

SABOAC 

SAGE 

SASP 

SBUY 

SC 

SEAREX 

SIO 

SMO 

SOl 

SOLRAD 

SPO 

SRM 

STP 

SUNYA 

TEM 

TOMS 

TSI 

TSP 

ULF 

UMT 

UPS 

URAS 

URI 

USDA 

USGS 

UY 

UYB 

YLF 

WMO 

WPL 

National Trends Network 

Niwot Ridge, Colorado 

National Weather Service 

New Zealand Antarctic Research Program 

Oregon Graduate Center, Beaverton, Oregon 

personal computer 

Pee Dee Belemnite 

proton elastic scattering analysis 

Principal fnvestigator 

Proton-Induced X-ray Emission 

Physikalisch-Meteorologischcs Observatorium Davos (World Radiation Center) 

photomultipier tube 

People's Republic of China 

Polar slratospheric clouds 

polyvinyl chloride 

Regional Acid Deposition Model 

Radiatively Important Trace Species 

residual standard deviation 

Scientific Application of Baseline Observations of Atmospheric Composition 

Stratospheric Aerosol and Gas Experiment 

Surface Air Sampling Program 

solar backscattered ultraviolet (satellite ozone instrument) 

sky cover 

Sea-Air Exchange Experiment 

Scripps Institution of Oceanography, La Jolla, California 

Samoa Observatory, American Samoa (GMCC) 

Southern Oscillation Index 

Solar Radiation Facility (GMCC) 

South Pole Observatory. Antarctica (GMCC) 

standard reference material 

standard temperature and pressure (O·C and 1 atm) 

State University of New York at Albany 

transmission electron microscope 

Total Ozone Mapping Speclrometer 

Thenno Systems Incorporated 

total suspended particulate 

ullra low frequency 

Universal Mean Time 

uninterruptable power supply 

(a commercial CO2 analyzer) 

University of Rhode Island, Kingston, Rhode Island 

United States Department of Agriculture 

United States Geological Survey 

ullraviolet 

ullraviolet B band 

very low frequency 

World Meteorological Organization, Geneva, Switzerland 

Wave Propagation Laboratory, Boulder, Colorado (ERL) 

142 {;{ U.S. GOVEI\_'\IEi\T I'I\I"'TI"G OFFICE 1990 775-320