Climate Monitoring and 

Diagnostics Laboratory 

No. 18 

Summary Report 1989 

U.S. DEPARTMENT 

OF COMMERCE 

NATIONAL 

OCEANIC AID 

ATMOSPHERIC 

ADMllllSTRATIGN ,...,..,,.T 'c-o~ ... ~ ... : 1' .. ~ 

ENVIRONMENTAL : l!J ; RESEARCH \ . .~ 4 .,.. 

LABORATORIES #r~ru o•" 

. I 
, 
Climate Monitoring 

and Diagnostics Laboratory 

No. 18 

Summary Report 1989 

Walter D. Komhyr, Editor 

Rita M. Rosson, Assistant Editor 

Boulder, Colorado 

December 1990 

U.S. DEPARTMENT OF COMMERCE 

Robert A. Mosbacher, Secretary 

National Oceanic and Atmospheric Administration 

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

Environmental Research Laboratories 

Joseph 0. Fletcher, Director 
NOTICE 

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

NOAA Environmental Research Laboratories. Use for publicity or advertising purposes of 

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

products is not authorized. 

ACKNOWLEDGMENT 

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 sale b) the l'<a11onal Technical lnformatoon Sel\ice. 528~ Port Ro)al Road 

prm~field. \'.\ ~~16 1 

11 
Contents 

CMDL Staff, 1989 ....................... ................................................................................................................... v1 

CMDL Station Information ............................................................................................................................. v11 

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

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

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

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

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

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

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

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

2.3. Samoa ....................................................................................................................................... 10 

2.3. 1. Operations ................................................................................................................... 10 

2.3.2. Programs ..................................................................................................................... 11 

2.4. South Pole ................................................................................................................................ 13 

2.4. 1. Operations .... ........................ ....................................................................................... 13 

2.4.2. Programs ..................................................................................................................... 13 

2.5. References ............................................. ............ ........ ........ ....................................................... 15 

3. Aerosols and Radiation Monitoring Group .......................................................................................... 16 

3.1. Continuing Programs................................................................................................................ 16 

3.1.1. Surface Aerosols .............................................................................................. ........... 16 

3.1.2. Solar and Thermal Radiation ........................................ ............................................... 18 

3.1.3. Solar Radiation Facility ............................................................................................... 21 

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

3.2.1. CN Counter Comparison at MLO ................................................................................ 22 

3.2.2. Radiative and Meteorological Effects of Transient Weather Disturbances at 

the South Pole During Winter ............................ ................ ................ .................... ... 24 

3.2.3. Confirmation of Ground-Based Measurements of Ozone and Stratospheric 

Aerosol and Computations of Umkehr Profile Aerosol Errors ....... .... .... ........ .. ......... 27 

3.3. References ......................... ....................................................................................................... 30 

4. Carbon Cycle Group . ........ ................................ ........ .... .................... ............................ ........ ........ .... ... 31 

4.1. Continuing Programs ............................................................................................................. ... 31 

4. 1.1. Continuous In-Situ and Flask Sample Carbon Dioxide Measurements . ....................... 31 

4.1.2. Flask Sample Methane Measurements ......................................................................... 34 

4.1.3. In-Situ Methane Measurements at MLO ................................................................ ...... 35 

4.1.4. In-.S itu Methane Measurements at BRW ...................................................................... 35 

4. 1.5. Flask Sample Carbon Monoxide Measurements .......................................................... 36 

4.2. Special Projects ........................................................................................................................ 38 

4.2. 1. AGASPIII .................................................................................................................. 38 

4.2.2. Shipboard Sampling ................. ................................................................................... 38 

4.3. References ................................................................................................................................ 39 

5. Ozone Group .......................................................................................... ................................ ........... 40 

5.1. Continuing Programs ................................................................................................................ 40 

5 .1.1. Total Ozone Observations ........................ ·.. .. .... .. . . . ... .. . . . . .. ... . .. .. . . .. . ... . .. . .. . . . . .. . . .. . . .. . ... .. . 40 

5.1.2. Dobson Spectrophotometer Calibrations .......................................................... ........... 41 

5 .1.3. Umkehr Observations ....................................... ........ .... .... .... ........ .... ........ ........ ........ ... 41 

5.1.4. Tropospheric Ozone ................................................. ................................................... 43 

5.1.5~ Ozonesonde Observations ........................................................................................... 43 

5. I .6. Validation of Satellite Instrument Ozone Data ............................................................ 44 

lll 
5.1.7. Stratospheric Water Vapor ........................... .. .................................. ........................... 44 

5.2. Special Projects ............................................................. ........................................................... 47 

5.2.1. Stratospheric Ozone Intercomparison Campaign ...................................... ................... 47 

5.2.2. Ozonesonde Observations at Mirny, Antarctica ................. .......................................... 48 

5.2.3. Ozonesonde Observations at BRW ....................................................................... ....... 48 

5.3. References ............................................................................................................................. ... 49 

6. Acquisition and Data Management ........................................................... ........................................... 50 

6.1. Continuing Programs ..... ........ ................ .... .................... ........ .... .... .... ........ ............ .... ........ .... ... 50 

6.1 .1. Station Climatology ..................... ........................................................................ ....... 50 

6.1.2. Data Management ..... ........ ........ .... .... .... .... .... .... ........ .... .... .... .... ................ ........ .... .... ... 54 

6.2. Special Project: Atmospheric Trajectories ................................................................................ 57 

6.3. References ..................................................................................... ........................................... 59 

7. Air Quality Group ................................................................................................................................ 60 

7. 1. Continuing Programs ................................................................................................................ 60 

7 .1. 1. Introduction .. . ... . . .. . ... . . . . . .. . .... .... ... . .. .. . . .. ......... .... ... . ... ... . .... .. .. .. .. .... ..... ... . ... .. . . ............ .. . 60 

7 .1.2. Atmospheric Udar·Validation Experiment ............................................... ................... 60 

7 .2. Special Project: Sulfur Monitoring at MLO ............... ........................ ....................................... 62 

7 .3. References ......... ............................ ........ .... .. .. .... ........ ............ ........ ............ ............ ........ .... ... .... 63 

8.0 Nitrous 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 CMDL Baseline Stations ............... 64 

8.1.3. Low Electron Attachment Potential Species.. .... ........................................................... 67 

8.1.4. Gravimetric Standards....................................................................................... ........... 67 

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

8.2.1. RITS Discoverer Cruise.................................... ............................................ ............... 69 

8.2.2. Ff-IR Spectrometer Archive Project ........................................................................... 69 

8.2.3. Airborne Gas Chromatograph ...................................................................................... 71 

8.3. References ............................................................................................................. ................... 72 

9. Director's Office ............................................................................... ................................................... 73 

9.1. A Joint U.S./U.S.S.R. Experiment for the Study of Desert Dust and its Impact on 

Local Meteorological Conditions and Climate .................... .... .... .... ........ ............ ........ ........ ... 73 

9. 1.1. Introduction...... ........................................................................................................... 73 

9. 1.2. Purpose ........................................................ ............ ................................................... 73 

9.1.3. Activities ...... ................ ............ ............................................................................ ....... 73 

9.1.4. Summary.............. ............................................................................................ ........... 74 

9.2. Annual Ozone Cycle and Decade Trend at South Pole ....... ....................................................... 75 

9 .2. 1. Introduction .. .... .... ........ .... ........ ............ .... .... ........ .... .... .... .... .. ...... .................... .... ....... 75 

9.2.2. Seasonal Ozone Variations at South Pole ......... ........................................................... 75 

9 .2.3. Long-Term Decreasing Ozone Trend at South Pole .. .... .... ...... .. .... .... ........ ........ .... ....... 7 5 

9.2.4. Summary and Conclusions .......................................................................................... 76 

9 .3. Wintertime Black Carbon Aerosol Measurements Over the Southwestern United States, 

December 1989 ... .................................................................................... ............................... 77 

9 .3.1. Introduction .. .................... ........ .... ........ ........ .... ................ ........ .... ............ ........ .... ....... 77 

9.3.2. Experimental Methods ................................................................................................. 77 

9.3.3. Results and Discussion ............................................. ................................................ ... 77 

9.4. References ..................................................... .................................... ....................................... 80 

10. Cooperative Programs............................... ........................................................................................... 81 

Precipitation Chemistry 

R.S. Artz ...................................................................................................................... 81 

iv 
Continuous Aerosol Monitoring with the Epiphaniometer al MLO 

U. Baltenperger, H.W. Gaeggeler, and D.T. Jost................................ ......................... 83 

Antarctic Ultraviolet Spectroradiometer Monitoring Program 

C.R. Booth, T. lucas, J. Yeh, and D. Neuschuler ........... :............................................. 85 

Chemical Resolution of Fine Aerosol Mass at MLO: The Role of Organic Mauer 

T.A. Cahill, l.K. Wilkinson, and R.A. Eldred ................................................... ........... 88 

Artificial Windshielding of Precipitation Gauges in the Arctic 

G.P. Clagett ................................................................................................................ 92 

UVB Monitoring Data from Rockville, Maryland 

D.l. Correll, C. Clark, R. Goodrich, and D. Hayes ..................................................... 93 

Roberston-Berger UVB Meter 

G.F. Cotton ................................................................................................................. 95 

The CSIRO Latitudinal Gradient Study: Methane Data from Air Samples 

Collected at CMDL Baseline Observatories and at Cape Grim, Tasmania 

P. Fraser, P. Steele, R. Francey, and G. Pearman .................................... .... ............... 97 

Secular Variation in the Carbon-13 Content of Atmospheric Carbon Dioxide 

I. Friedman, J. Gleason, and A. Warden...... ................................................................. 101 

Snow Bunting Nesting Study at Barrow, Alaska 

J.C. George, K. Bagne, and M. leinberger .................................................................. 104 

A New Look at Optical Depth Retrieval With the Multiple Field of View Sunphotometer 

P.F. Hein, J.M. Davis, and S.K. Cox ........................................................................... 105 

Tropospheric Nitrogen Oxide Measurements During Spring at Barrow 

R.E. Honrath and D.A. Jaffee ...................................................................................... 107 

Chemical Analyses of Atmospheric Particulates and Gases at MLO 

C.R. Jensen, X. Cal, and W.H. Zoller .......................................................................... 110 

A Temperature Inversion Climatology for Barrow: 1976-1985 

J.D. Kahl ..................................................................................................................... 112 

The Global Precipitation Chemistry Project 

G.E. Likens and J.M. Miller ....................................................................................... 115 

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

R. Larsen and C. Sanderson ........................................................................................ 117 

Total Nitrate Variations at Mauna Loa 

G. lee and B .J. Huebert ....... ................................ .................... ................ ............ ....... 119 

Seasonal and Latitudinal Trends in the t3Cf12C Ratio of Methane 

P. Quay, S. King, J. Stlltsman, and D. Wilbur......... ..................................................... 121 

Aerosol Constituents at American Samoa, November 1989 

D.l. Savoie, J.M. Prospero, R. Arimoto, and R.A. Duce ....... ....................................... 123 

Update on the 0-Ring Bias as Determined from MLO Precipitation Chemistry Samples 

G.J. Stensland ............................................................................................................. 125 

Trends of the Carbon Isolopi Composition of Atmospheric Methane in the 

Southern Hemisphere 

C.M. Stevens and A. Engelkemeir ................................................................................ 126 

Bromine and Surface Ozone Almosphric Chemistry at Barrow, Alaska, During Spring 1989 

W.T. Sturges, R.C. Schnell, S.J. Oltmans, S. landsberger, and S.-M. Li ...................... 127 

USGS Barrow Observatory 

J. Townshend...................................................................... .. ....................................... 130 

Radon from Distant Continents Detected at the Mauna Loa Observatory 

S. Whittle stone ...... ................................................ ........ ........ .... ................ ................... 131 

11 . International Activities 1989 . ........ ......................... ....... .... .... .. .. .... ........ ........ .... .... .... ........ ........ .... .... ... 134 

12. Publications and Presentations by CMDL Staff, 1989 .......................................................................... 136 

13. Acronyms and Abbreviations .... .... ........................ .... ........ ........ ... ......... ........ .... .... ........ .... .... .... .. .. ....... 139 

v 
Director's Office 

James Peterson, Director 

Bernard Mendonca, Deputy Director 

EUen Hardman, Secretary 

Antonio Diaz, Guest Scientist 

Dale Gillette, Physical Scientist 

Jon Kahl, NRC Post Doctorate 

Tezz Marquardt, CIRES 

Karen ~&Swain, CIR.ES Student 

Ted MuUen, Electronic Technician 

Rita Rosson, Editorial Assistant 

Russell Schnell, CIR.ES 

Patrick Sheridan, NRC Post Doctorate 

Donna Smith, CU Work Study 

Matthew Steiman, CU Work Study 

William Sturges, CIRES 

Denise Theede, Program Clerk 

Mark Vanderiet Elect. Tech. 

Bill Van Lecvan, CU Work Study 

Acquisition and Data Management 

Group 

Gary Herbert, Chief 

Dee Dee MitcheU, Secretary 

Mark Bieniulis, ClRES 

Michael Ellis, Physical Science Aid 

Joyce Harris, Computer Specialist 

James McCutcheon, CIRES 

Steve Roughton, Computer Assistant 

Kenneth Thaut, Electronic Technician 

Aerosols and Radiation Monitoring 

Group 

John DeLuisi, Chief 

Marilyn Van Asche, Secretary 

Larry R. Arnold, Physical Science Aid 

Barry Bodhaine, Meteorologist 

EUsworth Dutton, Meteorologist 

Rudy Haas, Mathematician 

Fred Kreiner, CIRES 

David Longenecker, CIRES 

Donald Nelson, Meteorologist 

Gayland Pounder, Physical Science Aid 

Patrick Reddy, CIRES 

Kevin Schlatter, CIR.ES 

Michael Shanahan, Physical Science Aid 

Scott Siao, Physics Science Aid 

Robert Stone, CIR ES 

Barbara Thomson, Physical Science Aid 

CMDL Staff, 1989 

Air Quality Group 

Joseph Boatman, Chief 

Dee Dee Mitchell, Secretary 

Cynthia Crouch, CIRES 

Laureen Gunter, Meteorologist 

Young Kim, CIRES 

Menachem Luria, CIRES 

John Ray, CIRES 

Hennan Sievering, CIRES 

Timothy Straube, Physical Science Aid 

Charles Van Valin, Research Chemist 

Dennis Wellman, Engineer 

Stan Wilkison, Computer Programmer 

Carbon Cycle Group 

Pieter Tans, CIRES 

Lee Prendergast, Secretary 

Todd Aten, CIRES 

Thomas Conway, Research Chemist 

Brian Hirsch, CO-OP 

Darryl Kaurin, CO-OP 

Duane Kitzis, CIRES 

Patricia Lang, CIRES 

Amy Lee, Data Analyst Technician 

Terry Lesoing, CO-OP 

RusseU Martin, CIRES 

Kenneth Masarie, CIRES 

Paul Novelli, CIRES 

Vernon Preston, CO-OP 

L. Paul Steele, CIRES 

Gregory Summers, CO-OP 

Kirk Thoning, CIRES 

Anthony Vaughn, Physical Science Aid 

Lee Watennan, Research Chemist 

Ozone Group 

Walter Komhyr, Oiief 

Lee Prendergast, Secretary 

Brandon Bird, Physical Science Aid 

Robert Evans, CIRES 

Robert Grass, Physicist 

Gloria Koenig, Computer Programmer 

Jeffrey Lathrop, CO-OP 

Kent Leonard, CIRES 

Samuel Oltmans, Physicist 

Dan Oppennan, CO-OP 

Christopher Platt, Physical Science Aid 

Frank Polacek, ill, Meteorological 

Technician 

Dorothy Quincy, CIRES 

Jim Wendell, Electronic Technican 

LaRae Williams, Physical Science Aid 

Vl 

Nitrous Oxide and Halocarbons Group 

James Elkins, Oiief 

Marilyn Van Asche, Secretary 

Christina Brunson, CIRES 

James Butler, Research Chemist 

Thomas Baring, Physical Science Aid 

ScO!t Cummings, Physical Science Aid 

Keith Egan, CIR ES 

Brad Hall, CIR.ES 

Bradley Halter, CIRES 

Thayne Thompson, Physicist 

Jeffrey Sczechowski, CIRES 

Thomas Swanson, CIRES 

Barrow Observatory 

Daniel Endres, Station Chief 

Timothy Quakenbush, 

Electronic Engineer 

Mauna Loa Observatory 

Elmer Robinson, Director 

Judith Pereira, Program Support Technician 

Ame Aust ring, Physical Sci en ti st 

Lynne Bonnan, Physical Science Aid 

John Chin, Physicist 

Thomu Defoor, Electronic Engineer 

Barbara Kereanan, Data Oerk 

Darryl Kuniyuki, NOAA Jr. FeUow 

Steven Ryan, Physical Scientist 

Mamoru Shibata, Electronic Technician 

Alan Yoshinaga, Chemist 

Samoa Observatory 

Steven Ryan, Station Oiief 

Carl Fanner, Station Oiief 

M. Emily Wilson-Godinet, 

Electronic Technician 

South Pole Observatory 

Elizabeth Crozer, NOAA Corps 

Mark \Viney, Elect. Engineer 

Carl Groeneveld, NOAA Corps 

Fred Schrom, ElecL Technician 
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: 

CMDL Station Information 

Barrow (IlRW) 

71.3233 

156.6067 

Okm 

GMT-9 

8:00 am-5:00 pm 

(907) 852-6500 

(907) 852-6500 

Officer in Charge 

NOAA/ERL/CMDL 

Pouch 8888 

Barrow, AK 99723 

Samoa (SMO) 

-14.2522 

170.5628 

0.03 km 

GMT-11 

8:00 am-5:00 pm 

011 -( 684) 622-7455 

011 -(684) 699-9953 

U.S. Dept. of Commerce 

NOAA - CMDL 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 arn-5:00 pm 

(808) 961-3788 

(808) 961-3788 

U.S. Dept. of Commerce 

NOAA - Mauna Loa Observatory 

P.O. Box 275 

Hilo, HI 96720 

U.S. Dept. of Commerce 

NOAA - Mauna Loa Observatory 

154 W aianuenue Ave. 

Hilo, HI 96720 

South Pole (SPO) 

-90.000 

0.000 

2.8 km 

GMT +12 

8:00 am - 5:00 pm 

Relayed through CMDL Boulder 

Officer in Charge, CMDL Program 

Box 400 US ARP 

C!O NA VSUPPFORANT AR CTI CA 

FPO San Francisco, CA 96692 

ATTN: South Pole #S-257 

I.Lowell 

CLIMATE MONITORING AND DIAGNOSTICS LABORATORY 

NO. 18 

SUMMARY REPORT 1989 

1. Introduction 

The year 1989 marked several significant events in the 

history and organization of NOAA's Geophysical Monitoring for Climatic Change (GMCC) program that was formed 

in 1972. The most important was the retirement of Dr. 

Lester Machta as the Director of NOAA 's Air Resources 

Laboratory, GMCC's parent Laboratory. Lester was the 

force behind the formation of GMCC, and he served as its 

Laboratory Director continuously through 1989. In the 

beginning there were only two GMCC Observatories--

Mauna Loa and the South Pole-and only a handful of 

scientists in Boulder. Under Lester's guidance and direction, 

GMCC grew to a $5 million per year program with nearly 

100 staff, four primary observatories, and many secondary 

sampling sites scattered over the globe. We continue to be 

gratified that the work we do has immediate application to 

international concerns about greenhouse gas climate 

warming and stratospheric ozone depletion. 

In January 1990, as part of an ERL reorganization, GMCC 

activities were transferred, along with those of the NOAA 

Climate Research Group, to a newly formed NOAA 

Laboratory, the Climate Monitoring and Diagnostics 

Laboratory (CMDL). Dr. Eldon Ferguson was named the 

CMDL Director. Eldon has many years of experience in the 

NOAA research laboratories, including previous direction of 

the Aeronomy Laboratory. With our new structure, we look 

toward the future with a positive view of the usefulness of 

our Jong-term monitoring activities and their application to 

research in climate and global change. 

The title change this year for our annual report reflects the 

reorganization described above. Note that although the title 

has changed, the numbering of the reports has continued. 

The research summary for 1989 of the Climate Research 

Group is not included in this report. 
2. Observatory Reports 

2.1. MAUNA LOA the CAMS delayed its full operation. In April 1989, the 

CMDL microbarograph at MLO was removed from service. 

E. ROBI:-.ISON In May, continuous monitoring of radon was begun with the 

installation of an instrument by ANSTO, and in December 

2. 1.1 . OPERATIONS The Paul Scherrer Institute of Switzerland installed an 

In January 1989, the eruption of Kilauea Volcano on the 

Island of Hawaii passed its sixth "birthday." During 1989 

the eruption activity caused an increasing amount of damage 

in Kalapana and coastal areas of the Hawaii Volcanoes 

National Park. Because of the attention given to this 

eruption by the media, it is useful to evaluate the eruption 

activity relative to the MLO operations and programs. First, 

these Kilauea lava flows originate from a site on the east rift 

zone of Kilauea 35 km south of Hilo and 58 km eastsoutheast of MLO at an altitude of 670 m MSL. The fumes 

produced by this eruption typically move toward the 

southwest from the emission site and are limited primarily to 

the marine boundary layer. Prevailing winds bring the 

volcanic plume haze to the western or Kona side of the 

island and from there the plume occasionally reaches MLO 

as part of the typical afternoon boundary layer upslope wind 

regime. The program of sulfur gas monitoring was able to 

document incidents of this nature. However, with regard to 

the Jong-term atmospheric background monitoring program 

conducted at MLO, no significant impact is believed to result 

from the Kilauea eruption because the Kilauea plume is 

mixed into the marine boundary l ayer and marine houndary 

layer upslope flow periods with or without volcanic 

constituents are generally excluded from the MLO record. 

Marine boundary layer events have always been of concern 

because they may have been influenced by biological effects 

(e.g., C02 vegetation exchange) or a wide variety of urban 

anthropogenic emissions. Thus we conclude that at present 

the additional presence of volcanic plume constituents in the 

marine boundary layer does not pose a problem for the MLO 

record. 

The 1989 winter meeting of the AGU held in San 

Francisco in December had a major symposium devoted to 

the photochemical field experiment (MLOPEX) conducted at 

MLO in May and June 1988 by NCAR and other 

atmospheric research groups. NCAR organized both the 

1988 experiment and the 1989 AGU symposium. 

2. 1.2. PROGRAMS 

The major CMDL and cooperative programs carried out at 

MLO in 1989 are shown in Table 2.1, which is similar to 

Table 2.1. of the 1988 Summary Report [Elkins and Rosson, 

1989]. with the following exceptions. Three programs were 

added (one CMDL and two cooperative) and three programs 

were dropped (one CMDL and two cooperative). The 

CMDL aerosol measurement program was expanded to 

include continuous monitoring of carbon aerosol concentrations using an aethalometer. This instrument was installed in 

May, although difficulties in matching the output signal to 

2 

epiphaniometer at MLO, a device that measures the total 

surface area of the atmospheric aerosol particles. Sunphotometer observations of turbidity for AES Canada and the 

collection of flask air sampl es for USGS, Denver, for 13C 

measurements were discontinued. Further information about 

some of the MLO programs is given next and also in 

subsequent sections where the technical results o f CMDL 

groups and cooperative investigators are presented . 

Carbon Dioxide 

The CMDL Siemans Ultramat-3 and the SIO Applied 

Physics IR C02 analyzers were operated side by side without 

significant downtime throughout the year. Routine 

maintenance and calibrations were done on both instruments 

as required and according to schedule. The Ultramat-3 

instrument has been in operation continuously since August 

5, 1987. 

The preliminary average MLO C02 concentration for 

1989 was 352.8 ppm. The growth rate between 1988 and 

1989 was approximately 2.0 ppm yr·1. This is an increase in 

the C02 growth rate compared with that of the early 1970s 

when it was only 0.7 ppm yr·l. Outgassing from the volcanic 

vents at the caldera and along the northeast rift of Mauna 

Loa continued to cause periodic observable peaks in some of 

the C0 2 records. These events occurred primarily between 

midnight and 0800 LST of the following day, during the 

downslope wind regime. The erratic traces in the C02 

records caused by these events were easily identified by 

visually scanning the chart records or by setting up a 

computerized data screening procedure. Table 2.2 gives the 

estimated frequency of Mauna Loa venting for 1989. Such 

venting episodes were detected and excluded from the MLO 

C02 record mainly on the basis of criteria for C02 concentration, C02 variability, and wind sector. The annual total of 

84 hours for these events in 1989 was 1.0% of the total time 

when C01 was measured at MLO. The criterion for the C01 

standard deviation screening was 1.0 ppm, which is the value 

suggested by Thoning et al. [1989). Estimated venting 

episode frequencies reported in previous Summary Reports 

[e.g., Elkins and Rosson, 1989; Bodhaine and Rosson, 1988), 

used other and sometimes less definitive criteria than were 

used to obtain the estimates of Table 2.2. 

Methane 

CH4 concentrations were available throughout the year 

from two types of observations: the continuous operation of 

a Carle automated GC, and weekly collection of air samples 

in 0.5-L glass flasks. The CH4 GC is at MLO, and flask air 

samples are collected at both MLO and Cape Kumukahi at 

sea level on the easternmost po int of the island. Although 

the Carle automated GC system can potentially monitor CO 
Gases 

C02 

Program 

C02, CH4 

CH4 

Surface 0 3 

Total 0 3 

0 3 profiles 

CFC-11, CFC-12, N20 

CFC-11, CFC-12, N20 , 

CC14, CH3CC13 

N20 

Total sulfur gases 

S02 

Aerosols 

Condensation nucle i 

Optical properties 

Stratospheric aerosols 

Black carbon 

Solar Radiation 

Global irradiance 

Direct irradiance 

Diffuse irradiance 

Turbidity 

Solar spectroradiometry 

Meteorology 

Air temperature 

Temperature gradient 

Dewpoint temperature 

Relative humidity 

Pressure 

Wind (speed and direction) 

Precipitation 

Total precipitable water 

Precipitation Chemistry 

pH 

Conductivity 

Chemical components 

TABLE 2.1. Summary of Measurement Programs at MLO in 1989 

Instrument 

Siemens Ultramat-3 IR analyzer 

3-L glass flaskst 

0.5-L glass flasks, through analyzer 

0.5-L glass flasks, P3 pump unitt 

Carle automated GC 

Dasibi oz.one meter 

Dobson spectrophotometer no. 76 

Dobson spectrophotometer no. 76 

(automated Umkehr method) 

Balloonbome ECC sonde 

300-mL stainless steel flasks 

HP5890 automated GC 

Shimadzu automated GC 

CSI flame photometric analyzer• 

TECO pulsed fluorescence analyzer• 

Pollak CNC 

G.E. CNC• 

TSI CNC• 

Four-wavelength nephelometer•: 

450, 500, 700, 850 nm 

Lidar, 694.3 nm 

Aethelometer 

Eppley pyranometers with Q, 

OGI, and RG8 filters 

Eppley pyrheliometer (2) with Q filter• 

Eppley pyrheliometer with Q, OGl, 

RG2, and RG!I filters 

Eppley/Kendall active cavity 

radiometer 

Eppley pyrgeometer with shading disk 

and Q filter• 

J-202 and J-314 sunphotometers with 

380-, 500-. 778-, 862-nm narrowband filters 

PMOD three-wavelength sunphotometer•: 

380, 500, 778 nm; narrowband 

Solar spectroradiometer 

Aspirated thermistor•, 2- and 40-m heights 

Max.-min. thermometers, 2-m height 

Hygrothermograph:j: 

Aspirated thermistors•, 2- and 40-m heights 

Dewpoint hygrometer•, 2-m height 

Hygrothermograph:j: 

Capacitance transducer• 

Microbarograph 

Mecurial barometer 

Bendix Aerovane•, 8.5- and 40-m heights 

Rain gauge, 8-in 

Rain gauge, 8-in§ 

Rain gauge, weighing bucket 

Rain gauge, tipping bucket• 

Fosken IR hygrometer• 

pH meter 

Conductivity bridge 

Ion chromatograph 

3 

Sampling Frequency 

Continuous 

1 pair wk· 1 

1 pair wk-1 

1 pair wk-1 

1 sample (24 min)·1 

Continuous 

3 day·I, weekdays 

2 day·I 

l wk·1 

1 pair wk·1 

1 sample (3h)"I 

1 sample (3h)-1 

Continuous 

Continuous 

1 day·1 

Continuous 

Continuous 

Continuous 

1 profile wk·1 

Continuous 

Continuous 

Continuous 

3 day·I 

1 mo·1 

Continuous 

3 day·I 

Continuous 

Discrete 

Continuous 

1 day·I 

Continuous 

Continuous 

Continuous 

Continuous 

Continuous 

Continuous 

5 wk·I 

Continuous 

5 wk·I 

1 wk·1 

Continuous 

Continuous 

Continuous 

Daily 

Daily 

Daily 
TABLE 2 .1. Summary of Measurement Programs at MLO in 1989--Continued 

Program 

Cooperative Programs 

C02 (SIO) 

C02 , 13C, N20 (SIO) 

Surface S02 (EPA) 

C02 , CO, CH4, 13C/t2e (CSIRO) 

C02, CH4, other trace 

gases (NCAR) 

To1al suspended particles (DOE) 

Turbidity (AES Canada) 

CH4 (13C/t2C) (Univ. of Washington) 

Total suspended particles (EPA) 

Instrument 

Applied Physics IR analyzer 

5-L evaculated glass flaskst 

Chemical bubbler system 

Pressurized glass flask sample 

Evaculated stainless steel flaskst 

High-volume sampler (I filter wk·l) 

Sonotek sunphotometer no. 5698 

35-L evacuated flask 

High-volume sampler 

Ultraviolet radiation (Temple Univ.) UV radiometer (erythema) 

Ultraviolet radiation (Smithsonian) 8-wavelength UV radiometer: 290-325 nm; 

narrowband 

Solar aureole intensity (CSU) 

Precipitation collection (DOE) 

Precipitation collection for 7Be and 10Be 

analysis (ISWS) 

Precipitation collection for organic acid 

analysis (Univ. of Virginia) 

Wet·dry deposition (ISWS, NADP) 

Aerosol chemistry, upslope-downslope 

discrimination (Univ. of Washington) 

Aerosol chemistry (Univ. of Calif.-Davis) 

13C(USGS, Denver) 

Various trace gases (OGC) 

HN03, llCI vapor, aerosols (URI) 

Ration (ANSTO) 

Aerosol surface area (PSI) 

All instruments are at MLO unless indicated. 

Multi-aperture tracking photometer: 

2, 5, IO, 20, 30' fields of view 

Exposed collection pails 

Aerochemetric automatic collector 

Aerochemetric automatic collector 

Aerochemetric automatic collector 

Nuclepore filters 

Programmed filter sampler 

10-L stainless steel flasks 

Stainless steel flaskst 

Filter system 

Aerosol scavenging of Rn 

Epiphaniometer 

•Data from this instrument recorded and processed by CA.VIS. 

t .MLO and Kumukahi. 

~MLO and Kulani Mauka. 

§Kulani Mauka. 

TABLE 2.2. Estimated Frequency of MLO Venting Effects* 

Jan. Feb. March April May June July Aug. Sept. 

Total time (hours) 11 3 2 3 7 3 II II 8 

*Criteria: C02 SD <::1.0 ppm; wind direction sector l 35'-225'; wind speed >i.35 m s·1. 

Oct. 

10 

Sampling Frequency 

Continuous 

I pair wk·1 

Every 12 days; 24-h 

(0000-2400) sample 

I mo·

1 

I pair wk·1 

Continuous 

1·3 day· 1 

I mo·1 

Every 12 days; 24-h 

(0000-2400) sample 

Continuous 

Con1inuous 

Continuous 

Integrated monthly sample 

Integrated 7-day sample 

Collection after each 

rain event 

Integrated 7 ·day sample 

Continuous 

Integrated 3-day sample 

I continuous and I downslope sample (3 days)·t 

Biweekly 

I set wk· I (3 flasks) 

Daily, 2000-0600 LST 

Continuous; integrated 30-min 

samples 

Continuous; integrated 30-min 

samples 

Nov. Dec. Year 

6 9 84 

and C02 concentrations as well as CH4, these species have 

not been analyzed with the MLO instrument. 

Ozone 

monitor; daily total ozone observations and Umkehr ozone 

profile measurements using automated Dobson instrument 

no. 76; and ozone profile measurements using balloonborne 

ECC ozonesondes launched from the Hilo NWS station . 

As in prior years, the MLO ozone measurement program 

consisted of three major phases: continuous surface air 

monitoring at MLO using a Dasibi model 1003-AH ozone 

4 

The MLO-Hilo ECC ozonesonde program through 

September was on a nominal weekly night schedule using 

large 9-kg plastic balloons. Beginning in October, the 
schedule was reduced to three soundings per month using 2-

kg rubber balloons. During 1989, 45 flights were launched; 

44 of these passed through the region of ozone maximum, 

and 39 were successful in providing data to burst altitude. 

The six flights that did not reach the expected peak altitude 

occurred in midsummer; the problem was diagnosed to be 

radiosonde battery failure occurring about 2 hours after 

launch. Obtaining a replacement batch of batteries corrected 

this problem. Of the 39 fully successful flights, 23 were 

made using the 9-kg plastic balloons and 16 using 2-kg 

.rubber balloons. For the 23 plastic balloons, the average 

maximum altitude was 41.4 km; only three failed to reach 

the 40-km target altitude. For the 16 successful flights using 

2-kg balloons, the average maximum altitude was 34.l km. 

The average height of the ozone maximum from the total of 

44 flights was found to be 25.6 km with a standard deviation 

of 2 km. No major trends were discernible in stratospheric 

ozone over Hawaii from the ozonesonde data. 

Total column ozone and Umkehr observations were made 

using automated Dobson instrument rt.o. · 76 whenever 

weather conditions permitted. The total ozone observations 

were made on 160 of the 235 MLO observation days, for an 

observational frequency of 68%. Cloudy weather was 

especially frequent through June, causing the 1989 observing 

frequency to be less than the 80% observing frequency of 

1988. During the year the MLO Dobson instrument was out 

of service 15 days, mainly due to computer control problems. 

From June 13 to August 15, a program of Langley plot 

calibrations was carried out for the WMO standard Dobson 

instrument no. 83 and for Dobson instrument no. 65 from 

Boulder. This calibration program included intercalibrations 

of Dobson instrument no. 83, MLO Dobson instrument no. 

76, and Japanese secondary or regional standard Dobson 

instrument no. 11 6. In addition, part of this summer study 

included simultaneous ozone observations from MLO and 

from a sea-level site on the western, or Kona, side of the 

island. This phase of the program was designed to evaluate 

possible influences of the atmospheric boundary layer on 

Dobson instrument ozone measurements and, in particular, 

on the Langley plot calibrations. 

The Dasibi ozone monitor operated continuously 

throughout the year and experienced only minor problems. 

Routine maintenance and calibrations were carried out on 

schedule. The air sample for the Dasibi is taken from the 

MLO main gas sampling stack through Teflon tubing about 

2-m long. 

Halocarbons and Nitrous Oxide 

Monitoring of atmospheric concentrations of N20, 

CFC-11, CFC-12, CC14 , and CH3CC13 continued at MLO 

using an automated RITS GC system and through the weekly 

collections of pressurized 300-mL air samples in stainless 

steel flasks. The flasks, as in prior years, were sent to the 

CMDL Boulder laboratory for analysis. The RITS GC 

provided ambient atmospheric air concentrations of the trace 

gas species every 3 hours. Although this rather complex 

monitoring system experienced a variety of problems during 

the year, usually resulting in short periods of downtime, 

5 

these conditions could usually be dealt with readily so that 

there were no prolonged or serious breaks in the RITS 

monitoring record. 

Su/fur Gases 

Sulfur gas monitoring continued throughout 1989, 

following the procedures described in the 1988 report [Elkins 

and Rosson, 1989). The two monitoring instruments include 

a CSI flame-photometric total sulfur analyzer (i.e., S02 plus 

any other sulfur gases but not sulfur compound aerosol 

particles) and a TECO pulse fluorescence S02 monitoring 

analyzer. The data from both of these instruments showed 

that the highest concentrations of both S02 and total sulfur 

typically occurred during midday upslope wind conditions. 

These events occurred, presumedly, because of the 

entrainment of Kilauea volcanic emissions into the marine 

boundary layer followed by the transport of this 

contaminated boundary layer air around the south end of the 

island and then north to the Kona area. Southerly downslope 

winds, which can contain evidence of C02 volcanic gas 

venting from the Mauna Loa summit (Table 2.2), were found 

to have little if any characteristic sulfur gas signature. More 

details of this sulfur monitoring program, which received 

major support from the ARL Air Quality Group, are given in 

Section 7.2.l of this Summary Report. 

Aerosols 

The MLO aerosol program consisted of a set of in-situ 

atmospheric monitoring instruments and a remote sensing 

ruby lidar system. In May 1989, the program added an 

aethalometer. This instrument monitors the atmospheric 

concentration of black carbon, i.e., soot or similar darkcolored particles, by tracking the changing optical density of 

a filter surface through which an air sample is drawn 

continuously. Although the aethalometer was originally 

installed in May and data were recorded subsequently by the 

CAMS, it became evident after a short period that extraneous 

signals were being included in the aethalometer CAMS 

record. Modifications requested from the manufacturer were 

made, and a fully usable instrument began operation early in 

1990. The aethalometer supplements the aerosol instruments 

already in operation at MLO, namely, the G.E. and TSI 

CNCs and the four-wavelength nephelometer, by monitoring 

specifically for black carbon aerosol concentrations. The 

Pollak CNC was used as a calibration standard for the G.E. 

and TSI CNCs as in prior years. 

The MLO ruby lidar system was used throughout the year 

to monitor aerosol concentrations in the stratosphere. 

During 1989, 31 lidar aerosol profiles were obtained. Figure 

2.1 shows the integrated non-Rayleigh backscatter (NRBS) 

coefficient results for 1989 as well as for years back to 

January 1985. These data are for the stratospheric layer 

between 16 and 33 km. 

As is apparent from Figure 2.1, the decrease in NRBS that 

began in 1987, following a period of increasing statospheric 

aerosol scattering in 1986, continued during 1989. The 

average NRBS for the 31 observations of 1989 was 0.70 x 

10·

4 sr 1 • This can be compared with the 1988 average NRBS 
4.5 

:;; 40 

0 

3.S ;.-

:; 30 

~\ft~f~ '-' " 

"" '2 5 

~ /: 20 

] 

~ 1.5 ~ 

~ 1.0 

05 

1985 1986 !9S7 1988 1989 ,T,t;i,.1,.1,1,1,., .r;l,i; ~,r,t;JToT"-r;i;v.;r.r;r;r,Q;J;T.r,~;r,;r.r;r.r.f;v,;1;r;r,r,r;r r.i;1, 

Fig. 2.1. Integrated :\'RBS coefficient profile for the stratospheric 

layer between 16 and 33 km at MLO, January 1985-Decembcr 1989. 

of 0.83 x 10·

4 sr·1 for 37 observations. Thus there was an 

apparent 16% decrease in yearly averages between 1988 and 

1989. This expected decrease follows from observations that 

no new volcanic perturbations of the statosphere were 

detected during 1989. Considering the relatively small 

NRBS trend during 1989, it appears that the stratosphere 

may be close to an aerosol base-le'!el concentration value. 

Solar Radiation 

The complement of MLO solar radiation measurements 

continued unchanged in 1989. Instruments exchanged during 

1989 included quartz pyronometer no. 1261 in May and RG8 

pyronometer no. 10153 in November. Replacement units were 

quartz pyronometer no. 12271 and RG8 pyronometer no. 

12616. The active cavity radiometer was in Boulder for 

calibration during September and October. In July the 

pyrheliometer began to indicate a 1 % degradation of output 

relative to the output of the active cavity radiometer. (The 

unit was subsequently replaced in early 1990). 

Sunphotometer calibrations were performed frequently, for 

a yearly total of 17. In June the efficiency of the calibration 

procedure was improved significantly by the development of a 

computerized data entry process using a small portable 

computer. 

The development program in solar spectroradiometry 

continued throughout the year, and numerous changes were 

made in both the mechanical components and the computer 

control system. A major goal for the coming year is the 

implementation of a calibration system that will be compatable 

with the long-term solar spectroradiometric goals of the 

program. 

Meteorology 

Several changes were made in the meteorological sensors 

during 1989. In September a new pressure sensor, SN 225, 

was installed. The old sensor, SN 109, had begun to show 

indications of a very slow lealc. Some past reports regarding 

below-average annual mean pressure at MLO [e.g., Bodhaine 

and Rosson, 1988; Schnell and Rosson, 1987] may have 

resulted in part from this faulty sensor as well as from the 

relatively short MLO climatological barometric pressure 

record. The MLO microbaragraph was talcen out of service in 

April 1989, leaving only the CAMS record to indicate 

pressures and patterns of pressure change. The mercury 

barometer is read daily and used as a check on the continuous 

CAMS pressure record. In November, the 2-m temperature 

and dewpoint sensors were replaced by a TSL hygrothermometer, model no. 1063, SN 46. The TSL was mounted on 

the 40-m tower at 2 m above the ground surface approximately 

30 m west of the previous sensor location. Since the TSL 

system displays maximum and minimum temperatures, as well 

as current temperature and dewpoint, less reliance is now 

placed on the conventional alcohol and mercury thermometers 

and the hygrothermograph in the standard NWS temperature 

shelter to provide for independent spot checks of atmospheric 

temperature and the daily high and low temperatures. 

Other than these changes, the standard set of meteorological 

observations as listed in Table 2.1 continued throughout the 

year without significant problems. The regular schedule of 

maintenance and calibrations was accomplished. 

During 1989 the MLO and NWS climatological files were 

searched and the monthly average precipitation record was 

compiled for the 34-yr period since MLO was established. 

Table 2.3 shows the MLO precipitation climatology for this 

period from January 1956 through December 1989. The 

average annual precipitation was 522 mm. The maximum 

annual total of 1249 mm occurred in 1982. The minimum 

annual percipitation was 155 mm, which occurred in 1983. 

January is the month with the highest average precipitation, 70 

mm, whereas June, with an average of only 15 mm, has the 

lowest monthly average. During this 34-yr period only 26 

months or 6% of the total number of months experienced no 

measurable precipitation. Only September and November did 

not have at least 1 month in this 34-yr period during which 

only a trace or less of rain was recorded. 

TABLE 2.3. Precipitation Climatology at MLO, 1956-1989 

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

Average (mm) 70 42 60 46 35 15 31 45 41 33 51 53 522 

Maximum (mm) 327 257 395 239 148 63 120 163 127 115 185 420 1249 

Year of maximum 1956 1982 1980 1986 1965 1983 1982 1957 1957 1979 1978 1987 1982 

Months :s; Trace 5 4 2 I 3 5 2 1 0 1 0 2 26 

6 
Precipitation Chemistry 

The precipitation chemistry program consisted of daily 

rainfall collections 5 days per week (or the replacement of 

exposed collectors in the case of no rain) at three stations: 

Hilo, 35 km on the Saddle Road, and MLO. In October, 

sample collections at Hilo and 35 km were terminated, but 

MLO was kept on a daily collector change schedule. The 

MLO precipitation chemistry laboratory kept to its 

analytical schedule and performed the required analyses on 

the samples collected locally as well as on precipitation 

samples received from SMO, BRW, and SPO. 

Cooperative Programs 

As shown in Table 2.1, 23 studies were carried out on a 

continuous basis at MLO under the CMDL Cooperative 

Investigator Program. Most of these were ongoing studies 

which have been operated within the MLO program for one 

or more years. At least one of these, the SIO C02 

investigations, predates the 1972 establishment of the 

NOAA/CMDL program. 

The cooperative program for 1989 includes two new 

investigations. In May, ANSTO put into operation a 

continuous ambient atmospheric radon monitor. The radon 

air sample inlet is at the 40-m level of the MLO tall tower. 

Section 10 of this Summary Report describes some initial 

results from this experiment. The second new program was 

installation of an instrument in December to monitor total 

atmospheric aerosol particle surface area with an 

epiphaniometer. This instrument was installed by the Paul 

Scherrer Institute, Switzerland. It is situated in the small 

building near the base of the 40-m tower. The air sample is 

obtained through a 6-m-high inlet adjacent to the building. 

Section 10 gives more details about this program. 

Two cooperative programs were discontinued during the 

year: Canadian AES turbidity observations using a 

sunphotometer were discontinued in June, and the USGS 

(Denver) flask air sample collection program for 13C 

determinations was discontinued in March. 

The MLO cooperative programs in 1989 also included 

several short-period studies (not listed in Table 2.1) during 

which individual investigators set up and operated their 

experiments more or less independently of MLO 

operations. The most extensive program of this type was a 

study of atmospheric ions performed by Georgia Institute 

of Technology during the summer months of June through 

August. Section 10 gives a more detailed description of 

this experiment. Another short-period study was conducted 

by DOE HASL, New York City, during March. The 

objectives of this program were to measure both radon and 

radon daughters at MLO, to identify possible daily 

concentration cycles of these species, and to bracket their 

limiting concentrations. Two other short-period projects 

were carried out by scientists from the NASA Ames 

Laboratory, Mountain View, California. These studies 

were directed toward obtaining absolute calibrations of 

sunphotometer systems. 

7 

2.2. BARROW 

D. ENDRES 

2.2.1. OPERATIONS 

BRW maintained a full schedule of data collection in 

1989, including increasing measurement frequency for 

some programs and the addition of several new programs. 

A 3-mo project requiring an increase in ozonesonde balloon 

flights was conducted to detect possible stratospheric ozone 

depletion during the Arctic winter and early spring. A 

program to measure background levels of NO and NOY was 

begun by the University of Alaska, Fairbanks. Aerosol 

filter samples were obtained by personnel in residence at 

the observatory from CIRES and NCAR during the Arctic 

haze season. The observatory's Temple UV-B meter was 

put back in service after being refurbished and checked at 

CMDL in Boulder. The 1989-1990 two-person CMDL/ 

SPO crew was detailed to BRW in the summer, and each 

member of the crew underwent 2 weeks of intensive 

training in observatory operations before leaving for the 

South Pole in October. 

The normal Arctic weather experienced at Barrow 

caused numerous vehicle breakdowns that disrupted the 

observatory routine throughout the year, and in particular, 

in the winter. Problems from broken shock absorbers to 

wheel bearings locking up were encountered. A new 

pickup truck arrived in November, and it helped alleviate 

some of the vehicle problems. 

A new electrical outlet was installed on a pole on the 

road to the station so that vehicles could be plugged in to it 

to keep them warm during the winter when road and power 

line maintenance was required. Road access to the 

observatory continues to be a major problem because of 

snow drifting during winter storms. Snow removal was 

done by DEW Line personnel and equipment whenever 

possible, especially when major drifting occurred. 

As with vehicle repairs and road maintenance, severe 

weather caused power line breakdowns that required repair 

efforts by observatory personnel to maintain good electrical 

power to the observatory. A major power failure occurred 

when a power line cutout blew apart during one storm. 

Repairs took several days before power was restored. 

The clean room at the observatory was rewired when it 

was noted that one of the two electrical circuits feeding the 

room was loaded to maximum capacity. New circu its were 

added during the rewiring. 

A double-wide trailer was obtained from NWS, Barrow, 

to provide for CMDL housing after government housing for 

CMDL personnel was cut back from two units to one by 

NWS. This trailer unit was reconfigured into two apartments. By the end of the year, remodeling of apartment B 

was finished and work began on apartment A. Walls were 

erected, floors installed, Sheetrock hung and textured, and 

some plumbing and electrical work done. A new boiler for 
the trailer heating unit was installed during December by 

station personnel when the old boiler broke down and was 

unrepairable. 

Numerous autorestarts in the solar/aerosol CAMS box 

were experienced throughout the year. Several attempts 

were made to locate the source of the problem. At one 

time an error in the clock reading of over 5 years, several 

months, and several hours was noted. The data acquisition 

system experienced no other problems. 

2.2.2. PROGRAMS 

Table 2.4 summarizes the 1989 measurement programs 

at BRW. Operational highlights were as follows: 

Carbon Dioxide 

BRW is still operating an old Uras 2T NDIR C02 

analyzer. Plans are being made to replace it. A chopper 

motor was replaced in the instrument when the old one 

failed. A new power line conditioner was installed after 

several power-related problems occurred. An old Cryocool 

H20 freezer unit failed and was replaced with a new FTS 

Systems freezer. No other problems were noted. Flask air 

samples were collected as scheduled with no problems. 

Methane 

A disk drive of the Carle GC data acquisition system 

was damaged by a power spike and was replaced in 

January. A new UPS was installed, replacing the old unit 

whose power capacity was underrated. A stream selection 

valve of the GC system plumbing was replaced when the 

old valve became misaligned. 

Surface Ozone 

A pinched air hose and a bad data display were the only 

problems experienced with the Dasibi instrument in 1989. 

The instrument operated well and was cleaned and 

calibrated as needed. 

Total Ozone 

Observations were made with Dobson spectrophotometer 

no. 91 on a routine schedule. The instrument was sent to 

Boulder for calibration in February, being temporarily 

replaced by Dobson instrument no. 86. In October, 

instrument no. 86 was returned to Boulder after replacement with Dobson instrument no. 91, which has a history of 

observations in BRW. 

Ozone Profiles 

ECC ozonesonde soundings were made during January 

16-April 19, 1989, from the NWS balloon facility at Point 

Barrow by a Boulder CMDL staff member with assistance 

from BR W staff. Instrument launches were conducted at 

approximately 3-day intervals for a total of 33 successful 

flights. Total ozone amounts measured by the ECC sondes 

ranged from about 340 to 520 Dobson units, except for one 

low ozone value of 307 Dobson units. The lower ozone 

amounts occurred on days of high tropopause. No evidence 

8 

was present in the measured ozone profiles of ozone 

depletion similar to that which occurs in Antarctica during 

the austral late winter and early spring. 

H alocarbons 

An ECD of the HP-5890 chromatograph failed in 

February and was replaced. The old detector was sent to 

Boulder. Several leaks developed in the system and were 

fixed, and a bad pump was repaired. The program was 

updated in April by visiting CMDL personnel, and the 

system underwent routine maintenance. In August a printer 

and a hard disk malfunctioned. These were replaced and 

the system was returned to service. CMDL staff returned 

in October to service and upgrade the system. A burnedout flow controller was found in December and replaced . 

Aerosols 

Plastic tubing in the vacuum system of the G.E. CNC 

had become worn and would no longer hold a vacuum. The 

tubing was replaced with copper tubing and tube connectors. A small amount of bleach was added to the water 

reservoir in the G.E. CNC. This has kept algae from 

growing in the water lines. Routine maintenance and 

calibrations were performed on schedule, and no other 

problems were noted. 

The aethalometer required several pump replacements. 

Installation of a new type of pump solved the problem. 

Several light bulbs for the aethalometer were incorrectly 

marked and found to be inadequate. They were replaced 

and no further problems were noted. 

The nephelometer power switch was replaced along with 

several chips. No other problems were noted, and the 

system operated well the rest of the year with only routine 

maintenance and calibrations. 

Solar Radiation 

Solar radiation measurements began at BRW March 2, 

1989, with receipt from CMDL, Boulder, of newly 

calibrated instruments, except for a NIP, which was 

temporarily lost in the mail. The "lost" NIP arrived in 

BRW 2 weeks later and was placed into operation shortly 

thereafter. During May a drive cable in the HP data logger 

system printer twisted and had to be adjusted and cleaned. 

During September the albedo rack was dismantled and 

cleaned. Several rusted bolts were replaced. The rack was 

leveled and several modifications were made to prevent the 

rack from sinking into the thawing tundra. Connectors 

were cleaned and all instruments were returned to service. 

The operational amplifiers driving the solar instrumentation amplifier board were replaced with upgraded operational amplifiers to correct a persistent noise problem. The 

old system had an unacceptable level of noise, and the new 

amplifiers appear to have reduced the noise. 

Meteorology 

The worst wind storm in the recorded history of Barrow 

occurred in February when winds averaged 33.6 ms·1 for 

several hours. A peak gust of 43.5 ms· 1 was recorded at 
TABLE 2.4. Summary of Measurement Programs at BRW in 1989 

Gases 

C02 

Program 

C02, CH4, CO 

CH4 , CO, C02 

Surface 0 3 

Total 0 3 

0 3 profiles 

CFC-I I, CFC-12, CFC-113, Np 

CFC-I I, CFC-12, CFC-113, N20, 

CCJ4 , CH3CC13 

N20 

Aerosols 

Condensation nuclei 

Optical properties 

Black carbon 

Solar and Terrestrial Radiation 

Global irradiance 

Direcl irradiance 

Terrestrial (IR) radiation 

Turbidily 

Albedo 

Meteorology 

Air lemperarnre 

Dewpoinl temperalure 

Pressure 

Wind (speed and direclion) 

Precipilation 

Precipitation Chem is try 

pH 

Conduclivity 

Cooperative Programs 

Total surface parliculates (DOE) 

Aerosol chemistry (URI) 

Precipitation gauge (ASCS) 

Magnetic fields (USGS) 

Various trace gases (OGC) 

C01 , CH4, other trace gases (NCAR) 

l3C, 1so. col (CSIRO) 

col. l3C, NlO (SIO) 

Halocarbon monitoring (Univ. of 

Calif., Irvine) 

Earthquake detection 

(Univ. of Alaska) 

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

NO, NOY (Univ. of Alaska) 

Ultralow frequency waves (Univ. of Tokyo) 

UVB (ARL) 

Air chemistry ions, organic acid, halogens, 

nitrous oxides (CIRES) 

Air chemistry (Florida State Univ.) 

Instrument 

URAS-2T IR analyzer 

3-L glass flasks 

0.5-L glass Oasks, through analyzer 

0.5-L glass flasks, P3 pump unit 

Carle automated GC 

Dasibi ozone meter 

Dobson spectrophotometer no. 91 

Balloonbome ECC sonde 

300-mL stainless steel flasks 

HP5890 automated GC 

Shimadzu automated GC 

Pollak CNC 

G.E. CNC 

Four-wavelength nephelometer 

Aethelometer 

Eppley pyranometers with Q and RG8 filters 

Tracking NIP 

Eppley pyrheliometer with Q, OGl, 

RG2, and RG8 filters 

Eppley pyrgeometer 

Sunphotometers with 380-, 500-, 778-, 

and 862-nm narrowband filters 

Eppley pyranometer and pyrgeometer 

Thcrrn istor, 2 levels 

.Max.-min. therrnometers 

Dewpoint hygrometer 

Capacitance transducer 

Mercurial barometer 

Bendix Aerovane 

Rain gauge, tipping bucket 

pH meter (samples analyzed at MLO) 

Conductivity bridge (samples analyzed at MLO) 

High-volume sample r (1 filter wk·1) 

High-volume sample r (1 filter wk·l) 

Wyoming shielded precipitation gauge 

Magnetometer 

Stainless steel flasks 

3-L stainless steel flasks 

5-L glass flasks 

5-L evacuated glass flasks 

Various stainless steel flasks 

Seismograph 

35-L stainless steel flasks 

Chemiluminscence 

Magnetometer 

Robinson -Berger meter 

Sample tubes and filters 

24 filters 

9 

Sampling Frequency 

Continuous 

1 pair wk·1 

1 pair wk·t 

I pair wk· 1 

1 sample (24 min)·l 

Continuous 

3 day-1 

1 (3 days)·t, winter 

1 pair wk·l 

1 sample (3 h)"l 

1 sample (3 h)" 1 

1 day· 1 

Continuous 

Continuous 

Continuous 

Continuous 

Continuous 

Discrete 

Continuous 

Discrete 

Continuous 

Continuous 

I day·1 

Continuous 

Continuous 

Discrete 

Continuous 

Discrete 

Discrete 

Continuous 

Continuous 

2mo·1 

Continuous 

I set wk·1 (3 flasks set ·

1) 

I pair wk·l 

I pair (2 wk)"1 

I pair wk·l 

I set (3 mo)·1 

Continuous, check 

site I wk·l 

change tap~ I mo·t 

1 (2 wk)·l 

Continuous 

Continuous 

Continuous 

I day·1 

I day·1 
BRW as well as at the NWS office in town. Several villages 

along the coast reported winds in excess of 44.8 ms· 1• The 

old BRW wind speed observatory record was 29.6 ms·I set in 

1986. BRW set five new record temperature lows during the 

last week in January and seven new temperature highs during 

the first week in February. 

A new syncro was installed in the Aerovane anemometer 

after it was determined that the old one had worn enough to 

give inaccurate readings. 

Several times during the year erratic readings were noted 

on the TSL dewpoint hygrothermometer. The problem was 

traced to bad connections in the wiring to the sensor card and 

to badly soldered joints of some components on the cards. 

Several printed-circuit boards were replaced throughout the 

year as connectors corroded. 

All maintenance was performed as scheduled and no 

further problems were noted. 

Precipitation 

Samples were collected routinely and sent to MLO for 

analysis. Even though July 1989 was the wettest July on 

record, few samples were collected. The cause was the low 

rate of precipitation during most 24-h periods. A light 

drizzle fell most of the month. 

Cooperative Programs 

Personnel from University of Alaska, Fairbanks, arrived 

at BRW to install an NO, NOY chemiluminescence converter 

into the instrument measuring these trace gases. NOY 

compounds are converted to NO using reduction with CO in 

a gold tube maintained at a temperature of 300'C. The 

instrument operated generally satisfactory with no major 

down time. 

The DOE high-volume air pump was replaced in May 

because the old pump was damaged during the February 

wind storm. The wind knocked the entire pump and housing 

onto its side. 

High winds caused drifting snow to enter the door of the 

USGS observatory building. The winds also caused the 

power lines to slap together, and a fuse was blown in the 

protonrnagnetometer. A tape data acquisition unit also 

developed problems during this time. 

Several new rain gauges were installed in 1989 by the 

Alaska Soil Conservation Service as part of an experiment to 

determine the efficiency of different types of collectors. The 

project involves several sites across the state. It has been 

shown that errors of up to 300% can be induced by some of 

the collection methods. 

Several types of air filter samples were obtained for and 

with personnel from NCAR during the spring Arctic haze 

episode. The program operated for 2 months, after which 

time all equipment was sent back to NCAR in Boulder. 

Several filter packs, known as "jet packs" were obtained 

for and with CIRES personnel to study the spring bromine 

injection from the ocean into the atmosphere when ice breakup 

occurs. The duration of this project was about 2 months. 

Argonne National Laboratory set up a small Shimadzu GC 

at BRW to search for non-CH4 hydrocarbons. The GC was 

damaged in shipping and never worked the way it was 

supposed to. 

The URI filter pump blew completely off the filter unit 

platform during the high winds in February. The pump was 

packed with snow and was moved indoors for servicing. 

After the pump was cleaned it ran well the rest of the year. 

The ultralow-frequency magnetometer recorder had 

several recurring problems. A drive belt tended to become 

loose and would not grip the drive gear. Personnel from the 

University of Tokyo were in BRW during August to replace 

the unit and install a new sensor. 

The Temple University UV meter was returned to service 

in July. Responsibility was turned over to CMDL for 

maintenance of the sensor/data logger unit. Data will be sent 

to ARL in Silver Spring for final analysis. 

NCS International installed an offshore navigation 

antennae near the BRW observatory during the summer. It 

was used as one part of a number of antennae set up to help 

ships navigate to Prudhoe Bay during the summer. BRW 

was chosen because of its remoteness and because of its 

proximity to a baseline survey marker. 

During September an acoustic sounder, or SODAR, 

system was installed by NOAA/WPL personnel. It is used to 

study inversion layer formation. Useful information will be 

gathered to enable the investigators to learn more about how 

surface inversions form in the Arctic, how they break up, 

how strong they get, and how long they last during the Arctic 

winter and spring. 

2.3. SAMOA 

J.C. FARMER 

2.3.1. OPERATIONS 

During 1989 there were many changes at SMO. A new 

station chief was hired in April. During this same period, the 

electronics technician was on maternity leave. The observatory was able to operate quite successfully, however, 

with the use of some temporary help. There were also many 

changes with the observatory facilities and the government 

housing. After the new station chief arrived, a major effort 

was put into upgrading the houses used by the CMDL 

observatory staff. The houses suffered from some neglect 

and limited budgets. New furniture was purchased, termite 

damage was repaired, and remodeling was done on the 

kitchens, bathrooms, and living-room windows. 

At the beginning of the year new power lines were 

installed at Matatula Point to help remedy recurring power 

outages, surges, and brownouts that periodically hindered the 

measurement programs. Trees were trimmed that were 

beginning to block some of the solar radiation instruments. 

Minor, but necessary repairs, were made to the main 

observatory building to improve the observatory's operation 

and maintain a safer measurement environment. The 

installation of new C02 sampling lines to Matatula Point 

began in late October. It was also decided to renovate the 

old Ekto building, since the small building at the base of the 

10 
tower was in very bad shape. This work was nearly completed 

by the end of the year. The hardwood posts around the outside 

of the observatory were stripped of the old varnish and two 

coats of marine varnish were applied. The generator failed to 

operate properly during November. A new battery and cable 

corrected the problem. 

2.3.2. PROGRAMS 

Table 2.5 summarizes the programs at SMO for 1989. 

Further descriptions of some of the programs follow. 

Carbon Dioxide 

Continuous C01 measurements were interrupted for most of 

April because of power problems at Matatula Point. A 

problem with the Air Cadet pumps used in the C01 analyzer 

system began surfacing in August. Apparently, because of the 

heavy load put on the pumps, the plastic heads were cracking 

on a regular basis, causing small leaks. This problem 

continued throughout the remainder of the year, necessitating 

frequent replacement of the damaged pump heads with new 

ones. A new cooler from FTS Systems was installed in place 

of a worn-out Cryocool unit; it has worked well, although a 

new design for a lid for the cooler is badly needed to prevent 

the accumulation of water within the cooler's alcohol bath. 

The installation of two new air sampling lines to Matatula 

Point was under way in late October and neared completion by 

the end of the year. The old Ekto building at the point was 

refurbished to house the water-trap system for the col 

sampling lines. 

Surface Ozone 

Observations continued during 1989 with no significant 

problems or downtime. 

Total Ozone 

Observations were conducted throughout the year without 

difficulty using Dobson instrument no. 42. The instrument 

was calibrated relative to secondary standard Dobson 

instrument no. 65 in May 1989. 

Ozone Profiles 

ECC ozonesonde soundings that had been made at SMO at 

a frequency of one per 2 weeks in 1988 were discontinued in 

July 1989. Six soundings were made during 1989. 

/lalocarbons and Nitrous Oxide 

The HP-5890 and the Shimadzu gas chromatographs 

operated all year with relatively minor problems. There was a 

continual problem with the Shimadzu GC not coming up 

online after a power failure. The only other problem during 

the year was loss of calibration gas in one tank during 

November. An old tank of calibration gas was found at the 

observatory and installed to maintain the system in operation 

pending receipt of new calibration gas from Boulder. The new 

tank of calibration gas arrived in late December and was put 

into use. The old calibration gas tank was then returned to 

Boulder so that it could be recalibrated. The chromatograph 

systems were operating on only one tank of calibration gas at 

the end of the year. The chromatograph systems' software 

was upgraded in April. 

Flask air sampling continued on a weekly basis when flasks 

were available. LEAPS flasks were substituted for the CMDL 

300-mL flasks once per month when possible. 

Aerosols 

The G.E. CNC had several problems during the year. It 

was sent to Boulder for repair on two occasions and was there 

at year's end. The nephelometer worked well throughout the 

year. The contacts on the two rotary switches of the 

nephelometer were cleaned in July when certain switch 

positions began giving erroneous readings. The aerosol air 

sampling stack showed signs of wear. Cracks were found in 

several places, including the sample ports. These were all 

repaired successfully. Severe corrosion was also noted on the 

frame for the stack. 

Solar Radiation 

The pyranometers and pyrheliometer were operated without 

difficulty. The filter-wheel NIP also operated well. One of 

the sunphotometers had a broken reset switch during the last 

half of the year. No replacement was received from Boulder. 

Meteorology 

The meteorology program added a dewpoint sensor to its 

list of instruments during 1989. The driest month and wettest 

month on record were recorded in 1989. In August SMO 

received only 1.5 cm of rainfall (0.5 cm at the NWS site) and 

in November rainfall totaled over 40.6 cm. All instruments 

performed well during the year. 

Precipitation Chemistry 

Daily precipitation samples continued to be analyzed for 

pH and conductivity during the year. These samples were then 

sent to MLO for further analyses. No problems with the 

Aerochem wet/dry collector occurred during the year. 

Cooperative Programs 

11 

The cooperative programs at the observatory changed 

somewhat during the year. Three programs were discontinued: the air sampling programs of the USGS, the Argonne 

National Laboratory, and the U.S. Bureau of Mines. Two new 

programs were added during 1989: the University of 

Washington and the University of California, Irvine, started 

programs to study 13CHJl2CH4 and light hydrocarbons, 

respectively. Similar programs exist at other CMDL observatories. 

The most significant cooperative program involvement 

during the year was the observatory staff's participation in the 

NASA GLOBE Program through the SEASPAN Project of the 

University of Miami. During the month of November, daily 

filter collections were made to provide ground measurement 

support for the program. A new collection system was 

installed on the Ekto tower from which fi.Iters were exposed on 

a daily basis. The previous filter collections had been made on 

top of the tower at Matatula Point. 
TABLE 2.5. Summary of Measurement Programs at SMO in 1989 

Program 

Surface 0 3 Total 0 3 0 3 profiles 

CFC-I I, CFC-12, N20 

CFC-II, CFC-12, Np, CC14, 

CH3CC13 

N20 

Aerosols 

Condensation nuclei 

Optical properties 

Solar Radiation 

Global irradiance 

Direct irradiance 

Turbidity 

Meteorology 

Air temperature 

Dewpoint temperature 

Pressure 

Wind (speed and direction) 

Precipitation 

Precipitation Chemistry 

pH 

Conductivity 

Cooperative Programs 

C02 , 13C, N20 (SlO) 

GAGE project: CFC-I I, CFC- 12, 

N20, Cll 3CCI3 , CC14 (OGC) 

Various trace gases (OGC) 

13C, 1so, C02 (CSIRO) 

Wei-dry deposition (NADP) 

Bulk deposition (EML) 

Hi-vol sampler (EML) 

Hi-vol sampler (SEASPAN Project) 

C02, CH4, trace gases (NCAR) 13C/12C ratio (Univ. of Wash.) 

Light hydrocarbons (UCl) 

Instrument 

URAS-2T IR analyzer 

3-L glass flasks 

0.5-L glass flasks, through analyzer 

0.5-L glass flasks, P3 pump unit 

Dasibi ozone meter 

Dobson spectrophotometer no. 42 

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 RG8 filters 

Eppley pyranometers with Q filte rs on tilted mounts 

Eppley pyrheliometer with Q filter 

Eppley pyrheliometer with Q, OGI, 

RG2, and RG8 filters 

Sunphotometers with 380-, 500-, 778-, 

and 862-nm narrowband filters 

Therm is tors (2) 

Max.-min. thermometers 

Polished mirror 

Capacitance transducer 

Mercurial barometer 

Bendix Aerovane 

Rain gauge, weighing bucket 

Rain gauge, tipping bucket 

Rain gauge, plastic bulk 

Aerochem wet/dry collector 

Fisher model 805 meter 

Beckman model RC-16C meter 

5-L evacuated glass flasks 

HP5880 gas chromatograph 

Stainless steel flasks 

5-L glass flasks 

HASL Chemetrics wet-dry collector 

Plastic bucket 

High-volume sampler 

High-volume sampler 

Evacuated stainless steel flasks 

30-L pressurized cylinder 

1-L evacuated stainless steel flasks 

12 

Sampling Frequency 

Continuous 

I pair wk·1 

I pair wk·1 

I pair wk"1 

Continuous 

4 day·1 

2mo·1 

I pair wk-1 

I sample (2 h)"l 

I sample (2 h)·l 

I day·1 

Continuous 

Continuous 

Continuous 

Continuous 

Continuous 

Discrete 

Discrete 

Continuous 

I day·1 

Continuous 

Continuous 

I wk- 1 

Continuous 

Continuous 

Continuous 

I day· 1 

I day·1 

I day- 1 (CMDL); 

I wk·l (NADP) 

I day·1 (CMDL); 

I wk·l (NADP) 

3 flasks wk- 1 

I h-1 

3 flasks wk-I 

(3 flasks set" 1) 

I pair mo·1 

I wk- 1, wet; 

discrete, dry 

Continuous (I bucket mo-I) 

Continuous (I filter wk- 1) 

Continuous (I filter wk- 1) 

I pair wk- 1 

2mo·1 

3-4 flasks qtr·l 
2.4. SOUTH POLE 

E. CROZER 

2.4. 1. OPERATIONS 

CMDL atmospheric monitoring programs at AmundsenScott (South Pole) station, Antarctica, are conducted in 

cooperation with NSF. Amundsen-Scott station is about 150 

. m from the geographical South Pole at an elevation of about 

2.8 km. 

Operations at South Pole arc conducted on an annual basis 

from about November l lo October 31 of each year. The 

station is accessible by U.S. Navy ski-equipped LC-130 

aircraft from about November l to February 15. During the 

rest of the year, the station is inaccessible and no supplies or 

mail can be delivered with the exception of one mid-winter 

airdrop in June. 

Measurements of atmospheric trace gas constituents are 

made in the CAF, which is located upwina of the main 

complex of the Amundsen-Scott station. Because the winds 

at the South Pole blow from the northeast 98% of the lime, 

the CAF is suitably placed lo sample uncontaminated air. 

The area upwind of the CAF is known as the Clean Air 

Sector and is off limits lo all personnel, vehicles, and 

aircraft. 

Materials were ordered in preparation for refurbishing the 

CAF during the 1989-1990 summer. The CAF requires 

electrical rewiring and re-insulation of the roof. Several 

building inspections were made by electricians in early 1989, 

and in the course of the inspections il was discovered that 

one power line coming into the CAF was supplying only 

95 V. The vohage was increased to JOO V by bypassing the 

CAF isolation transformer, which was causing part of the 

voltage drop. On the whole, very few power outages were 

experienced during the year. There were several planned 

outages while the CAF power supply was worked on and 

only a few unplanned outages of short duration. Most of the 

CAF equipment has UPS backup power supplies lo assure 

minimal data Joss. 

During the summer SPO acquired a Micro-VAX computer 

to replace the PDP-11 in use for many years. The installation of the new computer also included a dedicated VAX 

terminal at the CAF. The VAX could also be accessed via 

two personal computers at the CAF. At the present time 

there is only one line to the CAF, and all PCs and terminals 

must share this line. Plans call for inclusion of the CAF in 

the station's Ethernet network, allowing the PCs and 

terminal to access the VAX independently. The network 

would also facilitate data transfer from the CAF to the VAX 

because communications programs would not have to be 

used. 

Heating and cooling inside of the CAF continued to be a 

problem. During the summer, solar heating, added to 

interior hot spots generated by instrument clusters, resulted 

in uneven and elevated temperatures inside the CAF. These 

occurrences arc particularly evident when the sun shines 

through the CAF windows on calm days when outside air 

temperatures arc relatively warm. Pulling the interior shades 

over the CAF windows has minimal effect, as the air behind 

the shades and inside the three-pane windows heats to over 

l 50°F, transferring heat into the building. During the 

winter, cold outside temperatures in combination with strong 

winds, produce cold spots inside the CAF. These cold spots 

are in areas that arc distant from where instrument clusters 

normally generate enough heat to compensate for the cooling 

events. Circulation of air throughout the CAF could improve 

this situation. Installation of reflective film on outside storm 

windows would most likely reduce the amount of heat 

conducted through the windows and still allow light into the 

room. The use of reflective film, along with wall-mounted 

fans, will be tried during the summer of 1989-1990. 

In March there was a fire at the ATS-3 communication 

satellite ground station in Florida. The station was destroyed 

and SPO was left without ATS-3 communications for several 

weeks. The ATS-3 was the only satellite used for SPO 

communications this season. During this down time, 

communication with Boulder was maintained by reverting to 

HF transmissions through McMurdo to the Commercial 

Refile Center in Georgia, then via telex to Boulder. The 

University of Miami set up a temporary station to receive 

and send ATS-3 communications until the main groundstalion was rebuilt and activated in September. An unusual 

number of solar flare events blacked out HF communications 

several limes over the course of the winter and in the austral 

spring. 

2.4.2. PROGRAMS 

The CMDL programs al SPO during 1989 were essentially 

the same as in the previous year; atmospheric measurements 

included carbon dioxide, surface and total ozone, ozone 

vertical distribution, halocarbons, meteorology, and solar 

radiation. In addition, CMDL personnel operated a number 

of cooperative projects for other institutions. Only CMDL 

and affiliated programs were conducted at the CAF this year, 

contrary to past years when several other institutions 

maintained experiments there with their own personnel. 

Table 2.6 summarizes the programs at SPO. Further 

discussion of some of the programs follows: 

Carbon Dioxide 

The C02 analyzer system was thoroughly checked for 

leaks at the beginning of the summer. Some leaks were 

found and stopped, and the data quality improved. Flask 

samples were obtained weekly, with the method of sample 

collection alternating between use of a portable P3 pump unit 

and sampling through the C02 analyzer apparatus. 

Surface Ozone 

Surface ozone was measured with a Dasibi ozone meter. 

13 

No problems were experienced with the Dasibi instrument 

itself, although the data were not always recorded correctly 

by the CAMS system. 
TABLE 2.6. Summary of Measurement Programs at SPO in 1989 

Program 

Surface 0 3 

Tola! 0 3 

Ozone profiles 

CFC- I I, CFC-12, N20, CH3C03, CCl4 

CFC-I I, CFC-12, X20 

Aerosols 

Condensation nuclei 

Optical properties 

Carbon aerosols 

Solar and Terrestrial Radiation 

Global irradiance 

Dirct irradiance 

Turbidity 

Albedo 

Meteorology 

Air temperature 

Snow temperature 

Pressure 

Wind (speed and direction) 

Frost-point temperature 

Cooperative Programs 

C02, 13C, N20 (SIO) 

Total surface particulates (DOE) 

Various 1race gases (OGC) 

14C ~OAA/ARL) 

Snow acidi1iy (:\OAA/ARL) 

Interhcmispheric 13C/1

4

C (CSIRO) 

Cl 14, C02, CO ~CAR) 

Cltraviolct radiation ~SF) 

Polar stratospheric clouds (Univ. of Rome) 

Total Ozone 

Instrument 

URAS-2T IR analyrer 

0.5-L glass flasks, through analyzer 

0-5L glass flasks, P3 pump unit 

Dasibi ozone meter 

Dobson spectropholometer no. 82 

Balloonbome ECC sonde 

Shirnadzu aulomated mini-2 gas chromatographs 

300-mL stainless steel flasks 

300-mL stainless steel fl asks 

Pollack CNC 

G.E.CNC 

Four-wavelength nephelometer 

Aethalometer 

Eppley pyranomters with Q and RG8 filt ers 

Eppley pymeliometer with Q, OG I, RG2, 

and RGS filters 

SunpholOmeters with 380-, 500-, 778-, 

and 862-nm narrowband filters 

Eppley pyranometers with Q and RG8 

filters, downward facing 

Platinum resistor, 2- and 20-m heights 

Platinum resistor, 0.5 cm 

Capacitance transducer 

Mercurial barometer 

Bendix Aerovane 

Hygrometer 

5-L evacuated glass flasks 

High-volume sampler 

Stainless steel flasks 

3,000 psi spheres 

125-mL Nalgene flasks 

5-L glass flasks 

2.5-L steel flasks 

UV radiometer, data logger 

Optical lidar 

Sampling Frequency 

Continuous 

I pair twice mo·I 

I pair twice mo·1 

Continuous 

3 day·! 

I wk·l, summer, autumn, winter, 

I (3 day)'1, spring 

I sample (3 h)"1 

I pair wk·1, summer 

3 wk·1, summer 

2 day·1 

Continuous 

Continuous 

Continuous 

Continuous, summer 

Discrete, summer 

Discrete, summer 

Continuous, summer 

Continuous 

Continuous 

Continuous 

2 times wk·1 

Continuous 

Con1inuous 

2 mo·1 (3 flasks sampJe·1) 

Continuous 

( 4 filters mo· I) 

Twice mo·1 (3 flasks se1·t) 

500 psi day·t 

I (2 wk)'1 

I or 2 flasks mo· 1 

Daily, winier 

Periodic 

Instrumen1 inoperaiive 

Total ozone measurements were made with Dobson 

spectrophotometer no. 82. This instrument worked well all 

year without calibration drift. The only impediment to 

observations was the weather, especially when winter moon 

observations had to be made. 

plastic balloons were used for the flights almost exclusively. The balloons were launched from the ballooninflation tower. 

Very few instrument failures were experienced prior to 

September. September brought on a rash of unexplained 

radiosonde and ozonesonde failures with no consistent 

causes. Often sondes were launched on successive days in 

order to maintain the once every 3-day night schedule. 

Despite the age of the radiosonde signal device tracking 

equipment, no sonde data were lost due to its failure. A long 

period of bad weather and high winds contributed to the 

difficulty in launching the sondes during springtime. 

Ozone Profiles 

ECC ozonesondes were launched once a week for most 

of the year except during September through November 

months when launches were made every 3 days to study 

Antarctica springtime ozone depletion. Winzen 19K 

14 
Halocarbons and Nitrous Oxide 

Two automated gas chromatographs were operated all 

year. The systems were overhauled during the summer. 

GCl continued to function all year with no problems. GC2 

ran all year but experienced an unknown problem in July 

that affected the data. Column bakes and hydrogen purges 

were tried on GC2 with no improvement. An extra long 

hydrogen purge was made in September that improved data 

quality considerably. 

Halocarbon air sample flasks were filled during the 

summer and retrograded to CMDL Boulder. Samples were 

not collected during the winter. 

Aerosols 

Although problems were encountered with the Pollak 

counter all year, measurements were obtained. The G.E. 

CNC was not working at station opening in 1988. After 

completely dismantling the instrument it was discovered 

that the valve shaft was inserted 180° out of phase. When 

this was corrected, the instrument functioned all year with 

only minor problems. With the Pollak counter not always 

working properly, it was difficult to ensure that the G.E. 

CNC was always giving accurate readings. A new TSI 

CNC was installed early in the season and operated with no 

problems. It provided a good CNC record for the year. 

The nephelometer was on line all year with no problems. 

Solar Radiation 

This program was continued as in the past. A new 

albedo rack was installed at the beginning of the summer. 

The new rack proved to be sturdy and easy for one person 

to rotate by 180' when intercalibraling with upward-facing 

pyranometers. A new upward-facing pyranomeler was also 

installed. All instruments operated normally during the 

summer months. The pyranometers were removed from 

their mounts and stored during wintertime. There were a 

few problems with reinslallation at sunrise when it was 

found that electrical cables had been damaged by the high 

winds during spring (e.g., the motor on the tracking 

pyranometer failed). These problems were all corrected by 

the beginning of October. 

Meteorology 

As in previous years, meteorological observations 

included measurements of temperatures at 2 and 20 m, 

pressure, wind speed and direction, and frost point temperature. Snow surface temperature measurements made in the 

past at SPO were discontinued at the beginning of the 

summer. 

New temperature probes and cables for the 2- and 20-m 

measurements were installed during the summer. This 

proved to be a lengthy operation; calibrations were performed before, during. and after the installations. Calibrating the new probes took several days. using different 

calibration constants. The 10-m temperature probe failed on 

day 120 and was inoperative until day 174. The dewpoint 

hygrometer worked only until the temperature reached 

-60°C. At lower temperatures the values became negative 

and not reliable. 

Cooperative Programs 

The majority of the cooperative programs listed in Table 

2.6 were continued from the previous year. The USGS and 

SUNY A programs were discontinued. Problems were 

experienced with the alignment of the University of Rome 

aerosol lidars. Despite the large amount of work done on the 

lasers, the system was never operable. The NSF UYB 

radiometer was upgraded with new computers and new 

programs. It experienced various intermiuent problems 

throughout the year, which were worked on through frequent 

communications with BSI. the developer of the instrument. 

2.5. REFERENCES 

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

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

Air Resources Laboratory, Boulder, CO, 1988. 

15 

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

Climatic Changt, No. 17: Summary Report 1988, 142 pp., NOAA 

Air Resources Laboratory, Boulder, CO, 1989. 

Schnell, R.D., and R.M. Rosson (Eds.), Geophysical Moniloring for 

Climatic Change, No. 15: Summary Report 1986, 155 pp., NOAA 

Air Resources Laboratory, Boulder, CO, 1987. 

Thoning, K.W, P.P. Tans, and W.D. Komhyr, Abnospheric carbon 

dioxide at Mauna Loa Observatory, 2, Analysis of the NOAA GMCC 

Data, 1974-1985, J. Geophys. Rts., 94(06), 8549-8565, 1989. 
3. Aerosols and Radiation Monitoring Group 

B.A. BODHAINE (Editor), J.J. DELUISI, E.G. DUTTON, D.W. NELSON, AND R. STONE 

3.1. CONTINUING PROGRAMS 

3.1.1. SURFACE AEROSOLS 

The aerosol monitoring program at BRW, MLO, SMO, 

and SPO continued during 1989 as in previous years. CN 

concentration was measured continuously with a G.E. CN 

counter and daily calibration points were provided by Pollak 

CN counters at all stations. TSI (butanol-based) CN 

counters have been operated at MLO since May 1988 and at 

SPO since January 1989. TSI CN counters will be instaJled 

at BRW and SMO during 1990. After a I-year overlap of the 

new TSI CN counter with the existing G.E. CN counter at 

each station, the G.E. CN counters wilJ be retired. Aerosol 

scattering extinction coefficient (o,P) at 450-, 550-, 700-, and 

850-nm wavelengths was measured continuously at each 

station with a four-wavelength nephelometcr. Aerosol black 

carbon concentration was measured continuously using 

aethalometers at BRW since April 1988 and at SPO since 

December 1986. An aethalometer wilJ be installed at MLO 

during 1990. 

Figure 3.1 shows 1989 daily geometric means of CN 

concentration, a"'. and Angstrom exponent at the CMDL 

stations (except at SPO where only CN data were obtained). 

Three independent values of Angstrom exponent were 

calculated from the four channels of a"' data using the 

relation a = -ti.aop!ti.I.., where a is Angstrom exponent and I.. 

is wavelength. The interpretation of a in terms of aerosol 

size distribution was discussed by Bodhaine and DeLuisi 

(1985). Monthly geometric means of the 1989 aerosol data 

are listed in Table 3.1. A graphical presentation of the 

monthly geometric means of the entire data record for the 

four stations is shown in Figure 3.2. 

The BR W data in Figure 3.1 show a a"' maximum of 

about 2 x I0-5 m· 1 during winter and spring, typical of the 

well-known Arctic haze. The BRW Jong-term record in 

Figure 3.2 clearly shows this annual cycle in a •p· No 850-nm 

data for BRW are shown in Table 3.1 because of instrument 

problems that required deletion of much of the data at that 

wavelength. The BRW CN record shows a more variable 

semiannual cycle, having a maximum that usually coincides 

with the maximum in crap and another maximum in late 

summer or early spring. The secondary maximum in late 

summer is thought to be caused by local oceanic emissions 

of DMS gas that is eventually converted to sulfate aerosol 

[Radke et al., 1990). 

The MLO a"' data in Figure 3.1 are fairly typical; high 

values occur in April and May and low values in fall and 

TABLE 3.1. Monthly Geometric Means During 1989 of CN Concentration (cm·3), and O'sp (m- 1) at 450, 550, 700, 

and 850 nm, for BRW, MLO, and SMO, and of CN Concentration for SPO 

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

BRW 

CN 304 272 515 340 201 415 834 485 320 272 129 149 

cr,P (450) 1.35-5 8.18-6 1.62-5 1.21 -5 6.88-6 2.81-6 2.73-6 3.66-6 2.54-6 3.44-6 8.86-6 1.26-5 

cr,P (550) 1.25-5 7.54-6 1.40-5 1.02-5 5.61-6 2.21-6 2.40-6 3.32-6 2.49-6 3.12-6 7.84-6 1.10-5 

cr,P (700) 8.80-6 5.44-6 8.93-6 6.51-6 3.34-6 1.36-6 1.72-6 2.44-6 2. 11 -6 2.37-6 5.57-6 7.35-6 

MLO 

CN 258 181 181 190 220 249 242 247 230 233 176 235 

cr,P (450) 5.98-7 8.50-7 1.81 -6 2.74-6 5.17-6 1.84-6 1.76-6 1.07-6 9.20-7 1.52-6 1.14-6 5.90-7 

cr,P (550) 4.29-7 6.45-7 1.33-6 2.09-6 4.09-6 1.39-6 1.26-6 7.49-7 6.57-7 1.09-6 8.25-7 4.16-7 

cr,P (700) 2.92-7 4.94-7 9.75-7 1.56-6 3.05-6 1.02-6 8.41 -7 5.16-7 4.67-7 7.12-7 5.68-7 2.73-7 

SMO 

CN 285 24 1 190 232 230 174 23 1 222 27 1 267 201 

cr,P (450) 1.98-5 1.95-5 1.76-5 1.96-5 2.09-5 1.52-5 1.64-5 2.1 2-5 2.0 1-5 1.61-5 2.00-5 

cr,P (550) 1.90-5 1.84-5 I. 70-5 1.82-5 2.08-5 1.49-5 1.57-5 2. 10-5 1.92-5 1.57-5 1.93-5 

cr,P (700) 1.88-5 1.80-5 1.71 -5 1.75-5 2. 14-5 1.50-5 1.48-5 2. 12-5 1.90-5 1.57-5 1.96-5 

cr,P (850) 2.00-5 1.89-5 1.82-5 1.82-5 2.3 1-5 1.69-5 1.52-5 2.27-5 2.00-5 I. 78-5 2.12-5 

SPO 

CN 186 194 139 29 25 22 18 14 25 66 237 

A compact exponential format is used for O"' such that 1.35-5 = 1.35 x 10-s. 

16 
I I ?-il+-'!!'1i<-1r~'-;;i'R-.i~.,..,....,.+--r.111+--t--:--+---+-.--H1-.M~~?S 

~ ~ 

~Y+---11---+-++--+--l!f.~l+'liH-_,._+-"-"-4--~--+~ b 

s '3 

..,~ 

' 

~~~~~ -'---'-- ~...._~ _ _,_____. _ _.__J...__._~ 

. . n+-n-1r-:--to -lfr-t -H+ k/H-!IH..--l-..Hr---tth--Hl--+---+n e 

s ~ 

z z U -JIL-4ljl'--i---l-'1!.J.l~μ_---j--i--!..\--+--l~IA.,LWl!-.l-i-NU 3N 3 

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

1989 

AEROSOL DATA FOR SAMOA 

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

M 

~~ iJil I fficifT4 =B~~ ' M 

' 

_,_____. _ _.__ '---'----'------'--'---'------'----'--'---'-

·~~---~~-~~-~-~~-~-~~ 

M ~ 

, e ,M -+---+---+---+----1------+--__,___.___...._..___M e I 

s s z z uN Nu 

3 3 

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

1989 

AEROSOL DATA FOR MAUNA LOA 

i i ~~--::-:1""1HH?.4!iiw:....JJ+ ~H-Ai~--Ylit--ri~i-1:1t-1:v11-1.;..,-H--J-~ s 

~ . ~ 

~ 'i +-'' ---l---+--+--+--+---11---+-+--+--+--1----+,.. b 

s ' 3 

M- M I I 

E n+--Hl---i--.f.--+-c-+.--1---l--+--+--+--l-4n E 

s s z z 

~N ~ 

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

1989 

AEROSOL DATA FOR SOUTH POLE 

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

eN~"ii>--'i!H-...!.:..:ill.---t-+.-+-~i------:-+----,+.--,.,f'lt, .+--1---+N e 

s ~ 

z 

u 

3 

z +----t---+--+--+--H-+Hl--i.+--ff--+--+--1----+- U 

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

1989 

~ 

Fig, 3, I. Daily geometric means for 1989 of CJ , CN data, and Angstrom exponents (alpha) at BRW, MLO, and SMO; and of CN data at SPO. 

Data for MLO are included only for 0000-0800 LST. CJ data arc shown for 450 (dotted curve), 550 (solid curve), 700 (dashed curve), and 850 

(long-dashed curve) nm. Angstrom exponents were caldulated from 450- and 550-nm CJ data (dotted curve), 550- and 700-nm CJ •p data (solid 

curve), and 700- and 850-nm CJrp data (dashed curve). The CN data represented by squares Tor SMO and SPO are from lhe Pollak CN counter. 

winter. Large events in April and May, caused by the 

long-range transport of Asian desert dust in the upper 

troposphere to the vicinity of Hawaii, dominate the record. 

As discussed in the previous Summary Report [Elkins and 

Rosson, 1989), CJ'P values have been generally higher since 

the installation of the new nephelometer in 1985 and have 

not reached the low values expected in winter. A nephelometer-comparison experiment will be performed in 1990 to 

determine if the new MLO nephelometer is less sensitive 

than the old one. This should help determine if CJrp has 

generally increased at MLO. The increasing trend in CJi!> at 

17 

MLO is obviously caused by higher winter values in the 

l atter part of the record. No 850-nm data for MLO are 

given in Table 3.1 because of instrument problems that 

required deletion of much of the data at that wavelength. 

The MLO CN record shown in Figure 3.1 is fairly typical, 

giving an annual geometric mean concentration of 218 

cm·3, compared with 216 cm·3 for the previous year. Note 

that all MLO aerosol data presented here are in the form of 

geometric means during 0000-0800 HST (1000-1800 UT) 

in order to include data for downslope wind conditions 

only. 
L 

AEROSOL DATA FOR BARROW N n a ~ M ID ~ ~ ~ ~ M ~ M M 

% =-~,f-?--~iif .. r±4 r..+:¥~t>H i T T 

<;--~---

- r ------~----- ~. • 

~ I ~ f ~~r ~. --.-., ~ -~--.--1---+----l-+---'--~ 

?, .,:!'.;.. ~· -.! '! t _1,e__,-_...,.,_1-_'i,.._-....____.._,,_____.__'1----__.._-'---'i'-__:... u :'l .... 1--t--~ -' -..-- ' 

~ -, -31 -~ -r--r- N n a n M ID ~ ~ ~ M M ~ M M 

YEAR 

AEROSOL DATA FOR SAMOA n W H M ID ~ ~ ~ M ~ ~ ~ M 

'": ~ .... ~<:'J-

:2~_: ~i---~~ ~ ~- .- : -I 1. I i Hi 

~~~~}I I I 1 ~~ ;::: -: .... --+----- --------'-----'----'"' E 

\:--'-· _,.._ -~ 'i :..~ - ---.~;J"l....!.. ~ ~ 1- .... ?-.- "' • • 1 ~~ N c 

I ~ ~ ~ ~ --~--.----____.;---,--; --'------+ - n ~ n M ID ~ ~ ~ ~ ~ ~ M ~ 

YEAR 

: ·~- :1 ,\I .§_ '°-+1t--.-ft--tt----r.-<i-lc1• ~ + ·= 

g. ·~·""':"" •I --;;:;i \;j --1" ' \or 0~4----"f.----4-"l--·-+-~J~·-·~--\~·---t~~_,,_ 

s .. . ~~~I ' 

Fig. 3.2. Monthly geometric means ofCJ'E.'. CN data, and Angstrom exponents (alpha), at BRW, MLO, SMO, and SPO for the entire record. 

See the Figure 3.1 legend for plot details. Trend line data are given in Table 3.2. 

The SMO CJ"' and CN data continued as in previous years 

with no significant annual cycle or long-term trend. The 

SMO 1989 annual mean is about 1.80 x 10-5 m· 1 for CJ"' (550 

nm) and about 229 cm·3 for CN concentration, representative 

of the background marine boundary layer in that region. The 

SMO nephelometer experienced electronic problems in April 

and May; the automatic CN counter was down from 

mid-February to mid-June and mid-November through 

December. The CN record was augmented with Pollak 

counter observations when available. A detailed analysis of 

the SMO data record through 1983 was presented by 

Bodhaine and DeLuisi [1985). 

The SPO CN data for 1989 from the TSI CN counter are 

presented in Figure 3.1. These data show a strong annual 

cycle reaching a maximum of about 200 cm·3 in the austral 

summer and a minimum of about 10 cm-3 in the winter, 

similar to previous years. On the same graph are daily 

means from the Pollak CN counter. Instrument problems 

with the SPO nephelometer caused loss of CJ"' data for the 

entire year. Referring to the long-term data set for SPO 

shown in Figure 3.2, the CJ"' data generally show intermediate 

values in the austral summer, a minimum in May, and large 

events, sometimes exceeding 10·6 m·1, in late winter. These 

large aerosol events are caused by the transport of sea salt in 

the upper troposphere from stormy regions near the Antarctic 

coast to the interior of the continent. Analyses of the SPO 

data were presented by Bodhaine et al. (1986, 1987]. 

The least-squares trend lines in Figure 3.2 were calculated 

using the common logarithms of the monthly means for the 

entire data record. Trend data are summarized in Table 3.2. 

Similar trend lines have been calculated and presented in 

previous Summary Reports. 

3.1.2. SOLAR AND THERMAL RADIATION 

/nJroduction 

Surface radiation budget, atmospheric transmission, and 

aerosol remote sensing measurement projects at the four 

18 
TABLE3.2 Least-Squares Trend Analysis of the Common 

Logarithms of the Data Shown in Figure 3.2• 

Parameter Slope Intercept S.E. Trend,% yrt 

BRW CN 0.0179 0.826 0.285 4.21 

cr,P --0.00154 -5.14 0.378 --0.35 

MLO CN --0.00705 2.99 0.121 -1.61 

cr,P 0.0196 -7.70 0.311 6.05 

SMO CN --0.00807 3.12 0.111 -1.84 

cr,P --0.00185 -4.67 0.119 --0.43 

SPO CN --0.00333 1.93 0.431 --0.76 

cr,P --0.00660 -7.10 0.189 -1.53 

•Tue time axes in Figure 3.2 arc in fractional years, with a data 

point centered at the center of a month; e.g., Jan. 1974 = 74.042; 

Feb. = 74.125; etc. 

CMDL observatories continued through the year with no 

significant modifications in the measurement systems. Table 

3.3 shows the current observatory monitoring projects being 

overseen by the ARM group. Another ongoing project 

maintained by the ARM group is the surface radiation budget 

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

Erie, Colorado. Annual and diurnal cycles in the nearsurface radiation budget measured at BAO are discussed by 

Dutton [1990b]. A new surface radiation measurement 

project was begun on the island of Kwajalein in the Marshall 

Islands where downwelling solar and thermal infrared 

irradiances are being monitored. The Kwajalein data were 

used in an extensive satellite ground-truth comparison during 

April 1989. The site is also a candidate for long-term 

participation in the WCRP Baseline Surface Radiation 

Network. 

TABLE 3.3. Current Radiation Measurements 

at CMDL Observatories 

SWD swu LWD LWU RG8D DIRQ FWNlP SPIITM MISC 

BRW x x x x x x x x 0 

MLO x 0 0 0 x x x x x 

SMO x 0 0 0 x x x x 0 

SPO x x x x x x x x x 

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

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

LWD, Jongwave downward (sky emitted); LWU, longwave upward 

(earth emitted); RG8D, downward solar (RG8 filter, 0.7 to 3.0 μm) 

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

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

multiwavelength sunphotometer; MISC, miscellaneous-MLO: global 

diffuse solar, downward solar (OCH filter, 0.53 to 3.0 μm), 2-channcl 

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

standard); SPO: RG8 albedo, direct sun (RG8 filter). 

Processing and analysis of the data acquired during the year 

is complete. Results of these and other ARM radiation 

projects during past and preceding years have been used in 

numerous studies of surface radiation budget characteristics, 

light-sensitive atmospheric chemical reactions, satellite 

algorithm verification, climatic impact of volcanic eruptions, 

climatic trends and variability, errors in ozone remote sensing, 

surface optical properties, cloud optical properties, radiative 

transfer calculation verification, instrument development and 

improvement, and solar energy assessment and utilization. 

Data acquired are available in various published reports or 

directly from the ARM radiation project leader. 

Beginning in 1989 a different procedure for assuring the 

long-term calibration stability of the solar radiation sensors 

was implemented for the four CMDL sites. The new procedure involves swapping instruments once every 2 years 

with an instrument recently calibrated at the Boulder Solar 

Radiation Facility. This procedure replaces the system 

whereby the instruments' calibrations were monitored on site 

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

standards will continue as a secondary check on the 

instruments' calibration. 

ObservaJory Activities 

The BRW forced-air system used to prevent ice buildup 

on the pyranometer domes was further refined to improve its 

efficiency. The mounting mechanism that supports the 

global radiometers that observe the upwelling irradiances 

was overhauled; it had surtk into the permafrost and 

sustained minor damage. The pyrgeometers' mode of 

operation was changed by removing the temperature 

compensating battery from both instruments. The battery 

circuit data were only used for real-time monitoring but 

tended to interfere with other signals. 

The MLO Q global pyranometer was exchanged in May; 

instrument 12271 replaced 12616. The automated solar 

tracking dome, which houses continuous recording sunphotometers, operated during the year with only occasional 

unexplained failures. Data were nevertheless obtained 

during about 90% of the time, including unattended 

operation on weekends. The rain sensor that closes the dome 

in the event of significant precipitation is suspected of 

occasionally sending spurious signals, causing unwanted 

dome closures. All other radiation systems operated without 

problems during the year. 

SMO continues to be a severe testing site for radiation 

instrumentation; weather-tight instruments absorb moisture, 

spectral filter material provides a culture for various fungus 

and bacterial growth, and calibration constants drift 3-4 

times faster than expected from specifications. Nonetheless, 

the program is maintained by relatively frequent instrument 

exchanges and calibration corrections. Quartz pyranometer 

12274 replaced instrument 12276 in June. NIP replacement 

is planned during 1990. 

19 

At SPO, upward-facing pyranometer 12271 was replaced 

by instrument 12272 in January 1988. Pyranometer 12271 

demonstrated an extremely steady calibration over the past 

decade, but the base plate became warped, and leveling it 
became impossible. The new albedo rack support system 

served well during its first year of operation but has proved 

to be somewhat difficult to rotate to the upward-facing 

position. The rack is designed to keep the downward facing 

instruments 2-2.5 m above the surface. Jee forming on the 

instruments, particularly on the upward-facing pyrgeometers, 

is checked on nearly a daily basis by the SPO observers, but 

it still accumulates to an extent that data are lost. Data that 

can be determined to be degraded by icing are edited from 

the data base during post processing. 

Results 

Annual averages of total downward solar irradiances at 

BRW, MLO, SMO, and SPO for times that the sun is above 

the horizon, have been calculated and are shown in Figure 

3.3. Net solar radiation follows these variations except at 

BRW where the albedo can be highly variable. Although no 

significant long-term linear trends exist in the data of Figure 

3.3, some features are of considerable interest. The 

magnitude of the interannual variability over the length of 

time shown has only rarely been determined at any globally 

remote site. These variations relate to climatologically 

significant interannual variations in the Earth 's energy 

budgets. Both the MLO and the SMO records demonstrate 

rather steady year-to-year values punctuated by occasional 

large perturbations. Only the dip in 1982 in the MLO record 

can be partially explained; it is most likely due to the 

tremendous injection of aerosols into the stratosphere by the 

El Chichon eruption [Dul/on, 1990a]. Clouds can cause the 

interannual variations but the question of climatological 

interest then would relate to the cause of cloud variations. 

An interesting feature of both the BRW and SPO record, 

especially the SPO record, is the apparent long-term, slowly 

varying (autocorrelated) nature of the time series. Although 

the data records are too short to properly assess the statistical 

w 

u 

~''I 

z j!JU 

0 "" 

.. 

~ 300 

-r --r------r--r 

1.l ~t,ll4 \OA , ' \ /' • 

----- - . j ' . -- . 

50U1H POLE 

B4RROl'I 

. ----------------------- I Stl ,--.---.--r--.---r--r-----,.---. Iv 71 78 79 80 81 82 83 84 85 86 87 88 8~ 90 

YEAR 

Fig. 3.3. Annual average downward global solar irradiance at the 

four CMDL observatories. The average is for aU hours for which the 

true center of the sun was above the true horizon (refraction not 

included) for the entire hour or at e ither the beginning or end of the 

hour. 

significance of the indicated signals, such variations, if real, 

could be important in forcing climate change. Although the 

downward, or even net, solar irradiance at SPO has never 

been considered a major variable in climatic forcing, the 

atmospheric phenomena causing the SPO variations could 

affect a much larger portion of the Antarctic region. 

Net solar radiation measured at the top of the BAO 300-m 

tower has been used to substantiate a new concept for 

obtaining net solar irradiance at the Earth's surface from 

satellite measurements, as proposed by Cess and Vu/is 

[1989]. The comparison between the BAO net solar 

irradiance with ERBE top-of-the-atmosphere net solar 

observations verified the proposed nearly linear relationship 

between the two quantities during clear-sky conditions [Cess 

et al., 1990]. The new method provides a technique for 

determining surface net solar irradiance over most of the 

globe with higher accuracy than previously achieved while 

not requiring accurate knowledge of the underlying surface 

reflectance (albedo). Work is continuing in applying the 

technique to overcast and partly cloudy skies, with excellent 

initial success. 

For the past 9 years, nominally once a month, a 

comparison has been made at MLO of direct solar beam 

irradiance measurements from an active cavity radiometer 

(ACR) and from an on-line continuous tracking 

pyrheliometer (NIP). Results are shown in Figure 3.4. Each 

plotted data point is derived from an average of 12 ACR 

observations made 15 seconds apart and a simultaneous 

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

comparison was made within a month, all results were 

averaged to obtain the plotted point for the month. Although 

several rather large excursions are evident in the record, the 

long-term stability of the relative calibration of the two 

instruments is indicated to better than ±0.1 % until late 1989. 

Some of the larger excursions in the record are related 

20 

.. 

: 

0 

0 

l "'"n111111111 11111111 11111111111 1 1111 •• ••FTTlmlTTTTTTTfTTTJTI 111111111111111111111 "'''' 1I11111111; 1 jiillfTTTTTI 

0

81 82 83 84 85 86 87 88 89 90 91 YEAR 

Fig. 3.4. Time series of the ratio of direct solar beam irradiance 

measured at MLO with the continuous tracking J\'IP and wiLh the 

active cavity pyrheliometer. The comparisons were made 

sporadically; each plotted point represents an average fo1 a given 

month. Standard deviations associated with the monthly averages 

are also shown on lhe plot. 
to electrical measurement problems with the ACR. 

However, the shift at the end of 1989 was due to loss of 

sensitivity of the tracking NIP, after nearly 20 years of 

continuous operation. A new tracking NIP, 16657, was put 

on line in early May, and the ratio returned to near 1.00, as 

indicated in Figure 3.4. 

The relative transmission (commonly called apparent 

transmission) of the atmosphere over MLO is monitored with 

a pyrheliometer using a procedure developed by Ellis and 

Pueschel [1971]. The record since 1958 has been shown to 

be very sensitive to small changes in the absolute 

atmospheric transmission and reveals the effects of many 

volcanic eruptions and other aerosol events discussed by 

Mendonca et al. [1978]. The most recent published account 

of the MLO relative transmission record, its water vapor 

sensitivity, and its physical interpretation is given by Dutton 

et al. [1985]. The complete record into 1990 is given in 

Figure 3.5. Note the dramatic effect of the 1982 El Chichon 

eruption (including effects of smaller eruptio~S that have 

occurred since 1982) and the long recovery. The recovery 

appears to be continuing. Both the 12-mo unweighted mean 

apparent transmission centered on December 1989, and the 

individual value for January 1990, are higher than they have 

been since the time of the El Chichon eruption in 1982. The 

effects of the El Chichon aerosol on the different 

components of solar radiation (direct, diffuse, and total) at 

MLO were given by Dutton and Deluisi [1987]. 

3.1.3. SOLAR RADIATION FACILITY 

Operations 1989 

The SRF historical obligations were continued during 

1989. These obligations included, but were not limited to, 

hardware maintenance of NOAA SOLRAD network sensors 

and solar trackers; support of solar radiation measurement 

0 ·~ 

~n9.i 

l;; Vi 0 !J.1 

~ Vi 0 ,qz 

«?; 

~0 1 

II- n .. •n 

<': 

<q n.8? 

a:: 

Q'; n 88 

Cl. 

~ n.n; 

n.Bfi 

.... ~-··11 11 

/~#0:-0'h\·. . -: 

0 .8 :'; • • -r~-,--, ...,-,.-,--.,-- ..,-1 --r- r-r·• -r- • -,--,--. • ,.- '..,- ...,.. • -.- • -.~ 

r. R 6n 6Z 6< 66 68 70 7Z 7< 76 78 sn RZ R I Rr. n R 90 

I E 11R 

Fig. 3.5. Time series of the monthly means of the MLO apparent 

atmospheric transmission. The solid curve denotes lhe 12-mo 

running mean. The theoretical limit is determined from a 

LOWTRAN-modeled case with no aerosol and average MLO water 

vapor and ozone. NOTE: theoretical limit could be exceeded for a 

very dry and low aerosol case. 

programs at the CMDL observatories; installation in 

Kwajalein Atoll in the Pacific of ground-based solar 

radiation sensors; logistics support for and instrument 

calibrations at the BAO site east of Boulder; and instrument calibrations for other ERL laboratories. Thirty-five 

sites in addition to Boulder are supported with regularly 

recalibrated sensors and solar tracking equipment. 

Currently, a mixture of older equatorial mount trackers and 

the newer computer-controlled altitude/azimuth-style units 

are in use. 

Measurements 

The SRF maintained an operational array of sensors on 

the roof of the ERL building in Boulder. Global solar 

radiation measurements using pyranometers and directbeam measurements using pyrheliometers mounted on solar 

trackers were obtained throughout the year. These data are 

summarized in Figure 3.6. The SRF has a capacity for 

collecting data from up to 100 sensors if required. The 

typical mix of sensors on line consists of a core group of 

control sensors whose operation is traceable back to the 

mid-1970's and additional sensors for special studies or 

calibrations. Plots of the daily totals of hourly averaged 

global, diffuse, and direct beam radiation are shown in 

Figure 3.6. The diffuse component was computed as the 

difference between the measured global irradiance and the 

vertical component of the direct beam irradiance, measured 

with a pyranometer and pyrheliometer, respectively. 

Special additions to the measurement programs at the SRF 

during 1989 included installation of a prototype version of a 

rotating shadowband radiometer. It was installed during 

June and continues in operation. This sensor will eventually 

be added to the measurement array at the BAO site, after 

evaluation of its performance characteristics. 

A ground-level set of shortwave radi ation monitoring 

sensors was installed at the BAO site for comparison with 

the array that has been in place at the 300-m level of Lhe 

tower. An automatic tracker carrying two pyrheliometers, 

one with a clear window and the second fitted with an 

RG-8 cuttoff filter, was installed for direct solar beam 

measurements. A pyrgeometer, a clear-dome pyranometer, 

and a pyranome ter wilh an RG-8 dome were installed for 

global measurements. 

Standards Activities 

21 

The SRF reference absolute cavity radiometer, TMI Mark 

VI, serial number 67502 (manufactured by Technical 

Measurements Inc.), was used as a traceable standard for all 

the calibrations performed during 1989. This unit has a 

history of comparisons with other similar units dating back 

to the mid-1970s, and has been compared with Lhe reference 

cavities in the World Standard Group maintained in Davos, 

Switzerland, at regular intervals since its purchase in 1975. 

The most recent comparison to a world standard occurred 

during April 1989, at a WMO-sponsored comparison in 

Ensenada, Mexico. In addition to the international 

comparisons, the SRF reference is compared with other SRF 

cavities when conditions permit. Yearly comparisons with 
e 

I 

:z: 

l 

·~n1•111tul Gh,.,al 

10 D.ul> TQtah, 

1989 

10 

10 

111u~ 

Dail) T.-cah 

1989 

Ou..· .. t Beam 

O:ul) T1"llal' 1989 

lO 100 llO ~lO JOO llO 

r:ig. 3.6. Daily totals of global, diffuse, and direct beam irradiance at the SRF in Boulder during 1989. A pyranometer, a continuously 

shaded pyranometer, and a pyrheliometer were used, respectively, to collect the data. 

the SERI reference units have been conducted since 1985. 

Prior to 1985, the unit had participated in seven New River 

Intercomparisons of Pyrheliometers (NRIPs). 

3.2. SPECIAL PROJECTS 

3.2.1. CN COUNTER COMPARISON ATMLO 

Introduction 

The GMCC aerosol monitoring program at MLO was 

initiated in 1974 and consists of the continuous measurement 

of CN concentration and o,p· The aerosol program was 

described by Bodhaine [1983]; the complete MLO aerosol 

data record was presented by Massey et al. (1987). 

CN concentration is an important measurement at a 

background location such as MLO because it gives the total 

particle concentration regardless of particle size or 

22 

composition. At a background location the particle 

population will generally be an aged aerosol, the so-called 

accumulation mode, that has been subjected to natural 

coagulation, deposition, and cloud processes in the 

atmosphere. The CN concentration in the background 

troposphere, far from continents and anthropogenic 

activities, is generally of the order of hundreds of particles 

per cubic centimeter. The long-term geometric mean CN 

concentration at MLO is about 260 cm·

3. Thus, a CN 

counter sensitive in the range 0-1000 cm·3 is needed. 

An advantage of a CN counter is that it responds to 

particles in the 0.001-0.1 μm diameter size range, the 

so-called nucleation mode, as well as the accumulation mode 

(0.1-1.0 μm diameter). Therefore, CN data may be used to 

identify periods of time when a background sampling site is 

subject to local pollution influences, such as when the local 

wind flow is from the direction of a nearby biogenic or 
combustion source. At MLO, background data are usually 

acceptable during downslope flow and are contaminated 

during periods of upslope flow [Mendonca, 1969]. These 

periods of upslope flow are obvious in the CN record. 

Occasionally, most often in April-May, desert dust 

transported from Asian deserts is detected at MLO [Bodhaine et al., 1981; Parrington et al., 1983]. 

Instrumentation 

CN concentration has been measured continuously at 

MLO since 1974 using a G.E. automatic CN counter [Skala, 

1963]. This instrument measures CN concentrations in the 

range 3-300,000 cm·

3 with a response time of 2 seconds. A 

Pollak CN counter [Metnieks and Pollak, 1959] is located at 

MLO as the on-site standard. Both of these instruments 

employ the expansion cloud chamber technique and use 

water as the condensation medium. Daily calibration points 

obtained with the Pollak counter were used to calibrate the 

G.E. counter [Bodhaine and Murphy, 1980]. 

Because of continuing maintenance and calibration 

problems with the G.E. CN counter, a decision was made in 

1988 to install a TSI Inc. model 3760 alcohol-based CN 

counter at MLO and to phase out use of the G.E. counter. 

The TSI instrument uses a continuous flow of sample air 

through a cooling tube to produce a high supersaturation, and 

uses butyl alcohol as the condensation medium to produce a 

cloud. As the air stream passes through a focused laser 

beam, individual cloud droplets are detected, and an 

electronic pulse for each droplet is provided at the output of 

the instrument. A critical orifice and external vacuum pump 

provide a flow rate of 1.4 L min- 1• The maximum particle 

concentration detectable by this instrument is 10,000 cm·3. 

Coincidence counting errors (two or more particles in the 

laser beam simultaneously), although correctable, become 

significant for high concentrations (about 6% at 10,000 

cm·3). For ease of data acquisition, a frequency-to-voltage 

converter was used to provide a linear 0-10 V output scale in 

which 10 V is equivalent to 10,000 particles cm·3, giving a 

maximum count rate of 235.8 kHz. An additional 

logarithmic 0-10 V output, scaled at 2 V decade·1 from 0.1 to 

10,000 cm·3, was provided as a chart recorder driver. 

Because of its single-particle counting capability, the TSI 

CN counter is sometimes considered an absolute standard. 

It was decided to operate both the G.E. and TSI counters 

during an overlap period on the natural aerosol at MLO. 

Data could then be compared to determine if a correction 

factor is needed to maintain continuity for the long-term data 

set at MLO across this instrument change. 

Data Comparison 

Hourly mean data for February-March 1989 were used for 

a comparison of the two automatic CN counters operating at 

M LO. Figure 3. 7 is a direct tracing of a typical upslope 

wind event recorded for both instruments on a Leeds & 

Northrup chart recorder with 35-s time resolution on each 

channel. It is apparent from Figure 3.7 that not only do the 

general features of the data correspond well, but even the 

smallest details of aerosol variations are reproduced 

23 

faithfully by both instruments. This correspondence 

strengthens the credibility of both instruments and suggests 

that these small variations are indeed real. 

Unedited hourly mean data, recorded on the MLO data 

acquisition system during February-March 1989 for both 

instruments, are shown in Figure 3.8 (left). All data pairs 

were included regardless of data quality unless the data point 

for one or both instruments was missing. A linear regression 

was applied to the logarithms (base 10) of the resulting 1233 

data pairs. Although the fit is very good, large numbers of 

outliers are evident. These outliers were caused primarily by 

daily checks, calibrations, maintenance, and unknown 

reasons for both instruments. Rather than editing the data 

manually, which would require a subjective decision whether 

or not to accept each hourly data point, we wanted a simple 

objective method for removing outliers. 

The outliers were removed by calculating log(G.E.ffSI) 

for each data pair and then removing the points above and 

below 1 standard deviation from the mean of the distribution 

of the 1233 log(G.E.{fSI) data points. Also, any 

concentration larger than 1000 cm·3 was removed to restrict 

the comparison to the concentration range of interest for 

background monitoring at MLO. Figure 3.8 (right) shows 

the result of a linear regression on the remaining 997 data 

points after the outliers were removed. Note that the 

standard error of 0.029 translates to about 6.8%. The 

predicted values of G.E. CN concentration (calculated from 

the regression line) at 10, 100, and 1000 nuclei cm·3 differ 

from the TSI CN concentrations by about +10%, +2%, and5% respectively. 

It is possible that the negative bias of the G.E. counter at 

the higher concentrations could be partially explained by the 

data acquisition method. Data from both instruments were 

acquired at the rate of 1 Hz, and hourly arithmetic mearis 

were calculated by the data acquisition system. Since the 

TSI counter has a linear output, its hourly mean is an 

arithmetic mean. However, since the G.E. counter has a 

logarithmic output, its hourly mean is a geometric mean. 

"' 1000 

6 

5 

-!:'.? 100 

.., 1000 6 

0 

~ 

ci 100 

12 13 14 15 16 17 18 19 20 

March 13, 1989 (LST) 

Fig. 3.7. Time series comparison of TSI (lop) and G.E. (bottom) 

CN counter data during an upslope wind event at MLO on March 

t 3, 1989. These data were recorded on a multichannel chan 

recorder with 35-s time resolution. 
'( 

E 

u 

z 

u 

u.j 

d 

10,000 

1000 

100 

10 

10 

Unedited Data 

c 

Slope= 0.991 

Intercept= 0.014 

S.E. = 0.070 

r = 0.977 

n = 1233 

100 1000 10,000 

TSI CN cm·3 

"' ·e 

u 

z 

u 

u.j 

d 

10,000 

1000 

100 

10 

10 

Edited Data 

Slope= 0.966 

Intercept = 0.078 

S.E. = 0.029 

r = 0.992 

n = 997 

100 1000 10,000 

TSI CN cm·3 

Fig. 3.8. Comparison of TSI and G.E. hourly mean CN concentration at MLO for February-March 1989 for unedited data (left) and data with 

outliers removed (right). The linear regression was performed on the common logarithms of the data. 

Under conditions of high data variability, which commonly 

occurs at higher concentrations, the geometric mean may be 

significantly smaJler than the arithmetic mean. For example, 

if the CN concentration increases linearly from 100 to 1000 

cm·3 , the hourly geometric mean will be on the order of a 

few percent lower than the arithmetic mean. If the CN 

concentration increases exponentially, the difference will be 

about 4%. However, if the concentration varies wildly, the 

difference can be much greater. 

Conclusions 

As a result of this study, the credibility of the Jong-term 

G.E. CN counter data record at MLO has been substantiated. 

The calibration of the G.E. counter is established on site by 

the PoJlak counter; therefore, the present study also may be 

viewed as a comparison between the TSI and Pollak CN 

counters. Since the TSI counter is a single-particle counting 

instrument, many researchers in the aerosol field view it as 

an absolute instrument. This study provides additional 

verification for the calibration of the Pollak CN counter, 

particularly at the low concentrations occurring at 

background locations. Finally, this study shows that the 

water- and alcohol-based instruments give comparable 

results. 

3.2.2. RADIATIVE AND METEOROLOGICAL EFFECTS OF 

TRANSIENT WEATHER DISTURBANCES AT THE SOUTH 

POLE DURING WINTER 

Introduction 

Theoretical models of the atmosphere's general 

circul ation indicate that high-latitude regions are particularly 

susceptible to greenhouse warming because of global 

increases in the concentrations of radiatively active trace 

·gases [e.g., Schlesinger and Mitchell, 1985). Radiative 

forcing due to clouds, however, potentially far exceeds that 

due to gaseous greenhouse wanning [Ramanathan et al., 

1989). Thus, even smaJI changes in frequency, type, or 

spatial distribution of clouds may cause significant climate 

change in polar regions. Analyses of ground-based radiation 

measurements indicate that anomalous surface warming 

occurs in polar regions when clouds are observed [e.g., 

Cogley and Henderson-Sellers, 1984; Stone et al., 1989) and 

that the heating effects are monotonic with increasing cloud 

cover and/or cloud optical depth. The distribution of clouds 

is, in tum, controlled mainly by large-scale dynamical 

processes. The motivation for the present study is to 

understand better the processes that force the lower 

tropospheric radiation, temperature, and wind fields at the 

South Pole. 

Data 

SPO provides an ideal laboratory to study the processes 

thu.t affoct the climate of a large region of the Antarctic 

Plateau. Surface and upper-air meteorological data, 

sky-cover observations, and measurements of the surface 

radiation balance components for SPO were assimilated for 

this study. Two sources of upper-air data were analyzed: 

daily SPO 0000 UT rawinsonde profiles, and the NMC 

global, gridded, upper-air data. 

Data were stratified according to sky-cover (SC) 

observations. Only "clear-sky" (SC < 1/10) and "overcast" 

(SC > 9/10) conditions are analyzed here to contrast the state 

of a cloudy atmosphere relative to a clear one. Results for 

the austral wii:iter months of 1986 are presented. 

Results and Discussion 

Clear-sky conditions at the pole are characterized by a 

weak, steady katabatic flow of cold air from higher terrain, 

and a strong, persistent, surface-based temperature inversion. 

Transient weather disturbances, on the other hand, are 

characterized by increased cloud cover, surface wanning, a 

shift in wind direction, increased wind speed, and a 

weakening of the inversion. Surface warming is well 

correlated with enhancements of downwelling LW radiation 

which, in tum, correlate with increased sky cover [Elkins 

and Rosson, 1989). 

Clouds over the Antarctic Plateau tend to form in the 

warm layer capping the surface-based inversion 

[Schwerdtfeger, 1984). As was discussed by Stone et al. 

[ 1989), surface warming during the austral winter is due, in 

large part, to positive LW cloud radiative forcing. Carroll 

24 
[1983] suggested two other possible mechanisms for surface 

warming at the South Pole: (1) downward mixing of warm 

upper-level air, and (2) northerly warm-air advection (with 

north taken to be the Greenwich meridian). Hogan et al. 

[1982] showed that heat, water vapor, and aerosols are 

transported poleward at preferred levels 4i the troposphere 

when the position of the polar high-pressure ridge, normally 

centered over the high plateau, shifts to a more northerly 

position. 

It is clear that the surface temperature field at the South 

Pole responds to complicated, interrelated radiative and 

dynamical mechanisms that are somehow linked to 

large-scale circulation patterns. We seek to understand these 

mechanisms better in the context of climate change. 

Net Cloud Radiative Effects. Figure 3 .9 is a scatter plot of 

2300 and 0000 UT hourly mean values of net surface 

irradiance stratified according to 0/10 SC and 10/10 SC for 

the 1986 winter season. The 2300 and 0000 UT time periods 

were selected to bracket the rawinsonde launch times for 

subsequent comparisons. Figure 3.9 shows the mean values 

for all clear (35) and all overcast (20) days observed during 

the study period. A significant negative value of net 

irradiance characterizes clear days, and a slightly positive 

value is observed for overcast conditions. Nearly half the 

overcast days show net gains exceeding 10 W m·2, which 

represents a significant convergence of radiant energy at the 

surface available to warm the snow pack and near-surface 

air. 

Tropospheric Temperatures and Winds. Transport 

processes are crucial to the formation and spatial distribution 

of clouds over the Antarctic Plateau. An analysis of the 

surface and uppei level wind fields is therefore essential to 

gain an understanding of these processes. Figures 3.10 

shows surface wind roses for the 35 clear and 20 overcast 

days. Clear days are characterized by surface flow that is 

weak and from the easterly quadrant 90% of the time, 

(o) 

, ' I ' • 

I I , / '· ' / I / ''., 

,///// . I ! / ' I I I ; . I I 

__ .N -. 

--------· -· _.____,-- . 

,.,. --y--·- ... .. -i- -

.... '· \ \ . \ 

\ \ 

1-~--i ___ , ----< 

\ I \ \ . 

,__ __ ,., ____ ·-E- ; 

. \ \ '. · .. .. -... ; 

I \ \ \ \ \ \ /,_ I j~/ ' / I ' I i \ \ \ \ ,\ \ < ··..... ---:-... ,,/,,........ I , i .' : 

\ \ \ \ ,.-' ,_' ·-· ,....'£-· I I /I \ \_ \, x '-....... ·----!__.•· ./ ,/ • F 

\ ··.. '~ ,, ~ -- s' , , . ~ '---.. ! -.- ...,.-.• -.,~w~,-.,~S) ..... ----:-_ _. _, :f,~ 

-- $ ' •s < $ ................... _ ___ r ·- _.,...,,.~ 

c::::u ' I'S < 10 

WS I 10 

,_ 

....__ -~ -- ... ____ ._ 

-

40 

30 ~ 

E 20 

~ 

10 .., 

u 

z 0 < 

~-10 

"" "" --20 

..... 

.., 

z-30 

' ovc 0 CLR 

-40 -r-.-.-.-,r--,.....,......,...-.-........ "r" ........ ..,....,~.......-.............. ..,....,.."T""T ......... .......-1 

7S 100 12S 150 175 200 225 250 

DAY or YEAR 

Fig. 3.9. Selected 2300 and 0000 UT hourly mean values of net 

surface irradiance for April-August 1986. Circles denote clear 

conditions and filled triangles denote overcast conditions. The 

dashed and solid lines arc the mean values for the subsets of 35 

clear and 20 overcast days, respectively. 

whereas overcast days are distinctly characterized by much 

stronger, northerly winds. 

Coincident 0000 UT rawinsonde data were used to 

characterize the temperature and the wind profiles for clear 

and overcast conditions. Individual soundings were 

interpolated into prescribed height intervals to enable 

averaging the desired subsets of data for clear and overcast 

days. A shallow surface-based layer of large positive 

temperatu.re gradient is typically overlain by a rather deep 

quasi-isothermal layer of much warmer air throughout the 

winter at the South Pole. The boundary between these layers, 

in most cases, is readily defined by a significant inflection in 

temperature gradient between two adjacent layers, which is 

denoted arbitrarily as the top of the inversion. 

(b) -_ ..;.~ ---. 

... / 

/ /' I ' ,·, .' I v , , I 

:-R·==--

1 L-._........ I \ ,· __ u__ ... ,., /I I / / . , I / ! ; 

n ___ ---/,\ \1'. I I . U. ·'-./\ \-\\I i I - · '/' . \ \_ 

I .... ~ \ \ \ i ', ,, ... ,__ f --· CAUi i 1 I : 

I ----- ··~ I : I 

\ _>l/ii '; - ,\,\ · . ;;,/'/· '• 

\ \ \ \ \ . / ....... .L./ /, I l / I ! \ ' \ '\ ·, :.· ·---' -.... ,,,./ ~ ... " ..... /. ,/ I \_ \ \ ·' .... I ... ~ / .' ' 

·._ \. ." ~.. ..... __ +--..... ' ./'' ".·' ,,,,"" ' ,1 

· ... , ......,_ ....... ·~ ·"~ / - ./ I I-=~=~~ ' ,__ _..,.-· _, '. / 'll'L"'D SPUD 01/ !) ' - .. --.1--- ,.... / " • 

--~ ' ,., < $ ............ _ ,____ .......... /,.Cf:,"" 

-- I'S ;i 10 

--s-------· 

---· 

Fig. 3.10. Surface wind roses for (a) 35 clear days, and (b) 20 overcast days, during the austral winter of 1986. 

25 
Figure 3 .11 is a composite of the resultant mean temperature and wind profiles for the lowest 3165 m of the SPO 

atmosphere for all the clear and all the overcast days during 

the winter of 1986. The depth of the inversion under clear 

and under overcast skies is indicated, as well as wind barbs 

for selected levels. The mean clear-sky wind profile shows 

weak northeasterly flow through the entire depth of the lower 

troposphere. The overcast-sky profile, however, is characterized by much stronger winds increasing and veering with 

height, indicative of northerly to northwesterly warm-air 

advection. The increased wind shear observed through the 

boundary layer suggests that turbulence must also increase. 

Thus sensible and latent heat can more readily mix 

downward from the warm layer to the surface. The 

combination of cloud radiative forcing, warm-air advection, 

and vertical mixing weakens the surface inversion significantly when transient disturbances reach the South Pole. 

Stone and Kahl [1991] suggest that a change in climate in 

this region may be detected by quantifying the bulk wind 

shear in the lower troposphere and the intensity of the 

inversion. A detectable trend in either or both of these 

parameters may then be linked to changes in large-scale 

atmospheric circulation patterns. 

Synoptic-Scale Conditions and Trajectories. To 

understand better the synoptic-scale circulation patterns 

characterizing clear and overcast conditions at the South 

Pole, the upper-air NMC global gridded database was used 

6.0 :f' "i lli 5.0 _, 

Ill 

::c 

::c 

::::: 

..... 

_, 'l.0 c: 

3.0 

sf c. 

-20 -10 

TEHPERRTURE lCJ 

Fig. 3.11. Composite mean temperature profiles (to 6 km altitude) 

at 0000 UT for 35 clear days (dashed) and 20 overcast days (solid) 

during the winter of 1986 at the South Pole. Tops of surface 

inversions are indicated by horizontal dashed and solid lines for the 

clear and overcast days, respectively. The mean wind profiles for 

overcast and clear conditions are shown to the right of the 

temperature profiles. One full barb represents 5 knots. The tic 

marks on the ordinate axes show the levels to which individual 

sounding data were interpolated. 

to produce mean 500-mbar geopotential height fields for all 

clear and all overcast days during July and August of 1986. 

This period best represented the entire winter period, since 

clear and overcast days were reasonably well distributed. 

Each field was analyzed for the region poleward of 60'S 

latitude. The results for the set of (13) clear days and (9) 

overcast days are presented in Figure 3.12. 

The mean clear-day 500-mbar height field (Figure 

3.12a) is characterized by a weak, high-pressure ridge 

oriented northwest-southeast along the axis of the east 

Antarctic Plateau coupled with a region of weak, low 

pressure over West Antarctica extending from the Weddell 

Sea to the Ross Sea. For overcast conditions at the pole 

(Figure 3.12b) the high-pressure ridge intensifies and 

shifts to a more northerly position. The low-pressure 

system deepens in a two-lobe pattern, with one center 

over the Weddell Sea and another over the Ross Sea. The 

coupling of the Weddell Sea low and the high-pressure 

ridge over the plateau produces a sufficient pressure 

gradient force to break down the normal continental 

outflow of air caused by subsidence aloft and katabatic 

flow near the surface. A cyclonic flow results, providing 

the necessary mechanism to transport warm, marine air 

and energy poleward from the region of the Weddell Sea. 

This conclusion is supported by analyses of isobaric 

trajectories using the method of Harris (1982). Back 

trajectories at the 700-mbar level, extending 2.5 days 

upwind, are presented in Figure 3 .12 for all clear and all 

overcast days during the study period. A katabatic flow 

from higher on the plateau, initiated by intense regional 

radiative cooling [e.g., Parish and Bromwich, 1987). 

typifies clear-sky conditions, whereas rapid transport from 

the northern quadrant is characteristic of overcast 

conditions. Southwesterly transport has also been 

documented [Bodhaine et al., 1986), and apparently occurs 

when the gradient between the East Antarctic high-pressure 

ridge and the Ross Sea low-pressure center is of sufficient 

magnitude to force marine air poleward over the 

Transantarctic Mountain Range. 

Summary and Conclusions 

Analysis of the 1986 South Pole radiation data indicates 

that positive net cloud radiative forcing occurs during the 

austral winter when overcast conditions prevail. The 

resulting convergence of radiant energy in the lower 

troposphere combined with an increase in the horizontal 

and vertical flux of sensible and latent heat causes a 

significant weakening of the surface-based temperature 

inversion relative to clear-sky conditions. These processes 

are directly linked regionally to the dynamical state of the 

lower atmosphere, in that cloudiness and increased 

advection occur under rather well-defined synoptic 

conditions. Northerly transport of heat and moisture is 

favored when the Weddell Sea low-pressure system 

deepens and the East Antarctic high-pressure ridge 

intensifies, resulting in a pressure gradient force sufficient 

to reverse the normal katabatic outflow from the plateau. 

26 
20· w o· 20' £ 

60' w 

. . ,~. 

~· 

60' E 60' w 

oo" w eo' E eo' ~ 

100' E 100' W 

120° w 120' E 120' w 

140' w 140• E 140° w 140• E 

160· w 

(c) 160' £ 160° If (d) 160' E 

Fig. 3.12. Mean geopotentia.l height fields (in meters) for the 500-mbar pressure surface south of 60' latitude for (a) 13 clear days, and {b) 9 

overcast days, during July and August 1986, and 2.5-day 700-mbar back trajectories from the South Pole for (c) all clear days and (d) all 

overcast days during the winter of 1986. 

The inversion intensity and bulk wind shear are suggested 

as appropriate indices to characterize the South Pole 

troposphere as it responds to varying regional circulation 

patterns. As such, these parameters may be useful 

indicators of climate change. 

3.2.3. CONFIRMATION OF GROUND-BASED MEASUREMENTS OF OZONE AND STRATOSPHERIC AEROSOL 

AND COMPUTATIONS OF UMKEHR PROFILE 

AEROSOL ERRORS 

Introduction 

During the early phase of the El 

aerosols into the stratosphere, 

Chichon injection of 

ground-based lidar 

measurements provided the bulk of information on 

stratospheric aerosol profiles. These measurements, 

together with ozone profiles derived from balloon 

ozonesonde observations, were used to correct Umkehr 

ozone profiles that were subsequently examined for trends 

during the period 1979-1986. (Umkehr observations are 

adversely affected by stratospheric aerosols.) The lidar 

observations were point measurements, not necessarily 

co-located with Umkehr measurements, and although it is 

generally assumed that stratospheric aerosols rapidly 

become uniformly spread over the globe, and more so 

zonally, confirmation of the procedure we used was 

desirable. Our recent work has concentrated mainly on the 

application of SAGE II data for (1) validating the zonal 

27 
10·1 .----------~----~------..., 

(a) (b) 

I 

: .... 

,_ · .. ---~·;;;·-.--···._, .. _r_·-_···-· ;?< .. '.:: .... ::-. -.,.._-'-,.--"--

-.. ·~ ······ ..... 

10·} --:----::-::--::---::::-: ---:~-~,_......,,,....,._._._-~--~------' Bi.O M .S BS.Co as.s 86.0 86.S 87.0 87. S 88.0 88.S 89.0 IO~q,S 85.0 as.s 86.0 86.S 81.0 81.S 88.0 88. S 89.0 

Year Year 

Fig. 3.13. Comparison of aerosol optical thickness ('t) derived from lidar observations (dashed-curve) and SAGE II observations (solid 

curve), at (a) MLO and (b) Boulder, Colorado. 

representativeness of lidar aerosol and balloon ozone profile 

data for correcting Umkehr observations for aerosol effects, 

and (2) using SAGE II aerosol and ozone data alone for 

correcting ozone profiles derived from Umkehr observations 

made during 1984-1988. 

Stratospheric Aerosols 

The eruption of El Chichon produced greater than an 

order of magnitude increase in the equatorial stratospheric 

aerosol. Because of global spreading of the aerosols, 

Umkehr observations made in 1982 and later suffered serious 

errors. The only measurements of stratospheric aerosols 

available shortly after the eruption were from a network of 

lidar stations. Measurements from a selected set of northern 

midlatitude stations in this network were used to correct 

Umkehr ozone profiles from 1977 to 1986. The assumptions 

that were customarily invoked to reduce the lidar data 

introduced uncertainties that could only be assessed when 

SAGE II data became available. The SAGE measurements 

began in 1984, 2 years after the El Chichon eruption. We 

conducted a preliminary comparison of lidar and SAGE II 

measurements made at MLO (19.3 ' N) and Boulder, Colorado 

(40'N), with SAGE II measurements averaged zonally in 

10' -wide latitude bands centered at 20'N and 40'N. The 

SAGE II data were used to calculate aerosol optical 

thickness and lidar backscatter ratios (1 + aerosol/Rayleigh), 

with aerosol extinction-to-backscatter ratio assumed to be 

50. 

Figure 3 .13 compares aerosol optical thickness derived 

from MLO lidar and the Boulder lidar data with similar data 

from SAGE II observations. The 1988 SAGE II data were 

not edited for cirrus contamination and therefore are noisy. 

The comparisons show reasonably good agreement at both 

latitudes; however, note that there appears to be an annual 

cycle difference at the Boulder latitude. The difference is 

attributed to two likely factors. The first stems from use of a 

standard atmosphere to calculate Rayleigh backscatter. At 

40'N the seasonal variation in air density with altitude is 

strong, while at 20'N the variation is relatively weak. The 

second results from use of 1.03 as the lidar backscatter 

minimum found in the troposphere or near the tropopause. It 

turns out that the Boulder ruby lidar backscatter minimum 

frequently appeared to exist (we are not sure that this is real) 

in the troposphere at 5 km, or higher, above the surface. 

Also, the SAGE II data show that the tropopause aerosol 

minimum backscatter varies with season. It is suspected that 

the 1.03 minimum value may not be completely valid for the 

lidar normalization. Examination of 1985 and 1986 

backscatter ratios calculated from SAGE II data in the 

vicinity of the tropopause suggests that the normalization 

procedure could be improved. Table 3.4 presents provisional 

mean aerosol backscatter data, mean aerosol extinction data, 

and mean heights of aerosol backscatter minima for 20'N 

and 40' N, derived from the 2 years of SAGE II observations. 

Note the large variabilities in the extinction and the 

backscatter ratios at 40' N compared with those observed at 

20'N. The backscatter ratios exhibit an annual cycle (not 

shown) at 40'N with amplitude ranging from 1.01 to 1.06. 

Another useful comparison of aerosol profile features is the 

altitude of median optical thickness, i.e., the altitude at which 

one-half the optical depth is above and one-half is below. 

Figure 3.14 shows comparisons of MLO and Boulder lidar 

results with SAGE II results. Here again, the 1988 SAGE II 

data have not been edited for cirrus contamination. Overall, 

the gross features of these comparisons show good agreement. 

TABLE 3.4. Near-Tropopause Mean Minimum Values of 

Aerosol Extinction and Aerosol Backscatter Ratios, and 

Mean Altitudes of Aerosol Backscatter Minima at 20' N 

and 40'N, Derived for SAGE II Observations Made 

in 1985 and 1986 

Mean Backscatter 

Latitude, Extinction,• Minimum Mean 

'N km"' Altitude, km 

20 0.00045 ± 0.(XXJ2 l 14.6 ± 1.2 

40 0.00126 ± 0.00058 14.3 ±I.I 

Indicated variabilities are standard deviations. 

•Aerosol extinction to backscatter ratio is 50 ± 5. 

Backscatter 

Ratiot 

1.010 ± 0.003 

1.032± 0.015 

t Lidar backscatter ratio is defined by <Re + Me)IRe where Re is the 

Rayleigh backscattering and Me is Mie scattering. 

28 
1:.0 

?t.S 

- :1 0 

~ :v.s 

~ :o.o 

t:_ 19.S 

N I~ 0 

18 s 

16.0 

17.j .. 0 .!H.'S d~ 66.0 86 S d7. 0 d7.S 

Year 

88.0 8&.S 6J 0 

Fig. 3.1.4. Comparison of the altitude of median aerosol optical 

thickness for lidar observations (dashed curve) and SAGE II observations (solid curve). The upper plot shows MLO dat.a and the lower plot 

shows Boulder dat.a. 

An interesting difference in altitude of 1.5-2.0 km is evident 

for the measurements made at the. twQ different latitudes. 

Differences in aerosol profile features are related to 

differences in atmospheric structure and dynamics at the two 

latitudes. 

Ozone Profiles 

Computations of stratospheric aerosol-induced errors in 

Umkehr ozone profiles are ozone profile dependent. 

Therefore, it is important to use ozone profiles that are 

representative of conditions in the regions where 

stratospheric aerosol information is derived. Before SAGE 

II ozone data became available, aerosol-induced errors in 

Umkehr profiles were calculated using monthly ozone profile 

climatology data to 30 km altitude derived from ozonesonde 

flights made at MLO and Boulder. An average ozone profile 

from 30 to 80 km, currently in use for SB UV-2 satellite 

ozone data processing, is attached to the ozonesonde profile 

at 30 km. 

Table 3.5 compares monthly average SAGE II ozone data 

(zonal) with ozonesonde and Umkehr data at MLO. These 

results provide a measure of the zonal representativeness of 

the ground-based measurements. The second column in 

Table 3.5 is the bias in the comparison observations in terms 

of the percentage difference in ozone referenced to the 

SAGE data. The third column in the table is the 

root-mean-square difference between the two types of 

measurements, while the fourth column lists the 

root-mean-square differences with biases removed. 

Root-mean-square difference with bias removed is a better 

measure of the ozone sensing variability of the two types of 

measurements. In layers 1 and 2 the Umkehr and SAGE II 

measurements are fraught with difficulties; the Umkehr 

sensitivity to ozone is minimal, and the SAGE measurements 

are affected by cirrus. Therefore, these layers are not 

included in the comparison. 

Comparison of Lidar and SAGE /I Error Calculations 

Calculations of the stratospheric aerosol error to Umkehr 

ozone profiles were made with the monthly average 

ozonesonde and lidar data from MLO. Similar calculations 

were made through the use of the SAGE II data representing 

TABLE 3.5 Comparison of Climatological SAGE II Ozone 

Data at MLO With Climatological Ozonesonde 

and Umkehr Data at MLO 

Umkehr 

Layer 

No. 

Bias, 

% 

RMS Error, 

% 

RMS Error, 

(Bias Removed), 

% 

SAGE II and OzonLsonde Data Compared 

6 -5.6 7.2 4.5 

5 -2.5 3.2 2. 1 

4 -5.9 7.7 4.8 

3 -8.3 23.9 22.4 

SAGE II and Umluhr Data Compared 

9 -6.4 10.3 8.0 

8 2.5 6.4 5.9 

7 3.1 6.2 5.3 

6 -1.3 4.4 4.2 

5 4.5 5.5 3.3 

4 -3.5 6.8 5.8 

3 -6.1 5.7 5.2 

a 1 O' -wide latitude band centered at 20' for MLO. Plots of 

the results for 1985 are compared in Figure 3.15. The good 

agreement noted in this comparison suggests that the lidar 

.-.......... rn-10.s _ .. ···-- Layer 9 ~ ····~-- ................ ..-·"· ~--.. c -9. 0 · ....... · .. ~ .. 

() -7 5 \ :a . ·-- E- -6. 0 

ill 

() 

.... 

.... -5.4 

a. -4.8 ----- 0 

.-< -4.2 

0 -3.6 0 

Layer 8 

----.. -----... ,,~-- -"- -:.:..__-...,,.""_ ........ ----

---~ 

s... -3.0 

v 

a. 

~ -2.4 ··- Layer 7 

s... -1. 8 0 

s... -1. 2 s... 

(il -.6 

,. ··- ......... -- ~ 

01 2 3 4 5 6 7 8 9 10 II 12 

MONTH 

Fig. 3.15. Comparison of calculated stratospheric aerosol-induced 

errors in Umkehr profile layers 7-9 derived from SAGE II data for 

20'N latitude (solid-line curve) and MLO lidar data for 19' latitude 

(dashed-line curve), obtained in 1985. Layer 9 is at approximately 

45 km; layer 8 is at approximately 40 km; and layer 7 is at 

approximately 35 km. The indicated errors are well within the daily 

noise level of the Umkehr observations. 

29 
measurements used for the aerosol error corrections are 

reasonably representative of existing conditions. 

Conclusion 

The availability of SAGE II data has greatly increased the 

stratospheric aerosol data base for calculating errors to 

Umkehr ozone profiles. Moreover, whether ground-based 

lidar or satellite stratospheric aerosol data are used to 

calculate these errors, the results are consistent. This work 

served as an independent verification of the use of lidar 

stratospheric aerosol profile data to correct Umkehr 

measurements before 1984 when only lidar data were 

available. 

4. REFERENCES 

Bodhaine, B.A., Aerosol measurements at four background sites, 

J . Geophys. Res., 88, 10753-10768, 1983. 

Bodhaine, B.A., and J.J. DeLuisi, An aerosol climatology of 

Samoa, J. Atmos. 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., 

ll, 305-312, 1980. 

Bodhaine, B.A., B.G. Mendonca , J. M. Harris, and J. M. Miller, 

Seasonal variations in aerosols and atmospheric transmission at 

Mauna Loa Observatory, J. Geophys. Res .. 86, 7395-7398, 

1981. 

Bodhaine, B.A., J.J. DeLuisi, J.M. Harris, P. Houmere, and S. 

Bauman, Aerosol measurements at the South Pole, Tel/us, 38B, 

223-235, 1986. 

Bodhaine, B.A., J.J. DeLuisi, J.M. Harris, P. Houmere, and S. 

Bauman, PIXE analysis of South Pole aerosol, Nuc/. Instr. 

Meth., 822, 24 1-247, 1987. 

Carroll, J.J., Studies of atmospheric energy transfer at the South 

Pole, Ant. J . U.S .. 18(5), 248-249, 1983. 

Cess, R.D., and LL. Vulis, Inferring surface solar absorption from 

broadband satellite measurements, J. Climate., 2, 974-985, 

1989. 

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

surface solar absorption from broadband satellite 

measurements for clear skies: Comparison with surface 

measurements, J . Climate, accepted, 1990. . 

Cogley, J.G., and A. Henderson-Sellers, Effects of cloudiness on 

the high-latitude surface radiation budget, Mon . Weather Rev., 

112, 1017- 1032, 1984. 

Dutton, E.G., Comments on "Major volcanic eruptions and 

climate: a critical review," J. Climate, 3, 587-588, 1990a. 

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

diurnal cycle measured from a high tower near Boulder, CO, J. 

Climate, in press, l 990b. 

Dutton, E.G., and J.J. DeLuisi, Measurements of solar radiation at 

Mauna Loa observatory, 1978- 1985, with emphasis on the 

effects of the eruption of El Chichon, NOAA Data Rep. ERL 

ARL.J3, 35 pp., NOAA Air Resources Laboratory, Boulder, 

CO, 1987. 

Dutton, E.G., J.J. DeLuisi, and A.P. Austring, Interpretation of 

Mauna Loa atmospheric transmission relative to aerosols, using 

photometric precipitable water amounts, J. Almas. Chem., 3, 53~. 

1985. 

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

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

NOAA Air Resources Laboratory, Boulder, CO, 1989. 

Ellis, H.T., and R.F. Pueschel, Solar radiation: Absence of a;r 

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

Harris, J.M., The GMCC atmospheric trajectory program, NOAA 

Tech .. Memo. ERL ARL-116, 30 pp., NOAA Air Resources 

Laboratory, Boulder, CO, 1982. 

Hogan, A., S. Barnard, J. Samson, and W. Winters, The transport 

of heat, water vapor and particulate material to the South Polar 

Plateau, J. Geophys. Res., 87(C6), 4287-4292, 1982. 

Massey, D.M., T.K. Quakenbush, and B.A. Bodhaine, 

Condensation nuclei and aerosol scattering extinction 

measurements at Mauna Loa Observatory: 1974-1985, NOAA 

Data Rep. ERL ARL-14, 174 pp., NOAA Air Resources 

Laboratory, Silver Spring, MD, 1987. 

Mendonca, B.G., Local wind circulation on the slopes of Mauna 

Loa, J. Appl. Meteorol .. 8, 533-541, 1969. 

Mendonca, B.G., K.J. Hanson, and J.J. DeLuisi, Volcanically 

related secular trends in atmospheric transmission at Mauna 

Loa, Hawaii, Science, 202, 513-515, 1978. 

Metnieks, A.L .. and L.W. Pollak, Instruction for use of photoelectric condensation nucleus counters, Geophys. Bull. No. 16, 

School of Cosmic Physics, Dublin Institute for Advanced Study, 

Dublin, Ireland, 1959. 

Parish, T.R., and D.H. Bromwich, The surface wind field over the 

Antarctic ice sheets, Nature, 328, 51-54, 1987. 

Parrington, J.R., W.H. Zoller, and N.K. Aras, Asian dust: Seasonal 

transport to the Hawaiian Islands, Science, 220, 195-197, 1983. 

Radke, L.F., C.A. Brock, R.J. Ferek, and D.J. Coffman, Summertime Arctic hazes, Paper A52B-03 presented at the AGU Fall 

Annual Meeting, San Francisco, December 3-7, 1990. 

Ramanathan, V., R.D. Cess, E.F. Harrison, P. Minnis, B.R. 

Barkstrom, E. Ahmad, and D. Hartmann, Cloud-radiative forcing 

and climate: Results from the Earth Radiation Budget 

Experiment, Science, 243, 57-63, 1989. 

Schlesinger, M.E., and J.F.B. Mitchell, Model projections of 

equilibrium climatic response to an increased carbon dioxide 

concentration, in Projecting the Climatic Effects of Increasing 

Carbon Dioxide, DOEIER·0237, edited by M.C. MacCracken 

and F.M. Luther, pp. 81-147, U.S. Dept. of Energy, Carbon 

Dioxide Research Division, Livermore, CA, 1985. 

Schwerdtfeger, W., Weather and Climate of the Antarctic, Elsevier 

Science, Amsterdam, 1984. 

Skala, G.F., A new instrument for the continuous measurement of 

condensation nuclei, Anal. Chem., 35, 702-706, 1963. 

Stone, R.S., and J.D. Kahl, Variations in boundary layer properties 

associated with clouds and transient weather disturbances at the 

South Pole during winter, J. Geophys. Res., 96 (D3), 

537-5144, l 991. 

Stone, R.S., E.G. Dutton, and J.J. DeLuisi, Surface radiation and 

temperature variations associated with cloudiness at the South 

Pole, Ant. J. U.S., 24, 230-232, 1989. 

30 
4. Carbon Cycle Group 

P. NOVELLI (Editor), T.J. CONWAY, D.G. KlTZIS, P.M. LANG, R. MARTIN, K. MASARIE, 

L.P. STEELE, P .P. TANS, K.W. THONlNG, AND L.S. WATERMAN 

4.1. CONTINUING PROGRAMS 

4.1.1. CONTINUOUS IN-SITU AND FLASK SAMPLE 

CARBON DIOXIDE MEASUREMENTS 

The concentration of atmospheric C02 was measured with 

continuously operating NDIR analyzers at the four CMDL 

observatories during 1989 as in previous years. Monthly and 

annual mean C02 concentrations [in the WMO 1985 mole 

fraction scale (X85)] are given in Table 4.1. These values are 

provisional, pending final calibrations of station standards. 

Preliminary selected daily average C02 concentrations for 

1989 are plotted versus time for the four observatories in 

Figure 4.1. The C02 measurement programs and data for 

MLO (through 1985) and SMO (through 1987) were analyzed 

in detail; and the results were published in 1989 [Komhyr et 

al., 1989; Thoning et al., 1989; Waterman et al., 1989]. 

The continuous C02 measurements made at BRW in 1989 

exhibited an increase in the number of hourly-averaged 

concentrations showing high short-term variability. Figure 

4.2 shows unselected (except for instrumental malfunctions) 

hourly-averaged BRW data for 1987, 1988, and 1989. 

Higher .variability, especially in the months of May, June, 

July, and August was evident in 1989. In addition, the 

distribution of standard deviations of the hourly averages 

showed an increase in the number of hours with large (>0.3 

ppm) variability for 1989. These variable concentrations 

were not always correlated with wind directions from the 

town of Barrow (except for January and February), but did 

show some correlation with temperature. Anomalously 

warm periods showed high variability in C02• Continuous 

CH4 measurements from BRW showed this same effect. 

TABLE 4.1. Provisional Monthly C02 Concentrations 

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

from the 1989 Continuous Analyzer Data 

BRW MLO SMO SPO 

Jan . . 360.88 352.72 351.29 349.03 

Feb. 358.16 353.16 351.62 348.99 

March 359.15 353.68 351.38 348.90 

April 359.27 355.29 351.40 348.98 

May 358.74 355.54 35 1.66 349.75 

June 357.04 355.02 350.73 350.20 

July 349.34 353.70 351.04 350.55 

Aug. 344.48 351.30 351.07 350.96 

Sept. 346.18 349.89 350.62 351.04 

Oct. 351.19 350.19 350.21 351.08 

Nov. 355.81 351.42 350.63 350.42 

Dec. 358.29 352.76 350.60 349.89 

Annual 354.88 352.89 351.02 349.98 

E' 

Q. 

~ 

N 

0 

(.) 

360 

355 

350 

345 

345 

360 

355 

. 

\ .. • . . ~ .... ~ 11.·1~ .• ""-\ .1• ~. ~ 

.~ . . -' . :r ::; # ~ ... ... ,\ ·• ':.. .,. ·~ 'ti#' 

\ 

.. .. )• ,~ .. • :· :1. BRW 

MLO 

- • a..\. 350 -~- --- .... 

345 

36 0 

355 

SHO 

35 0~----------:----------------------4 

345 

SPO 

JAN f'EB HAR APR HAY JUN JUL AUG SEP OCT NOV OEC 

1989 

Fig. 4.1. Preliminary selected 1989 daily-average C02 concentrations from the in-situ measurements at BRW, MLO, SMO, and SPO. 

Because June, July, and August were unusually warm in 

1989, this suggests a relationship between C01 and CH4 

concentrations and temperature during the summer. 

In 1989 the conversion from synthetic-air standards to 

natural-air C02 standards was begun. Natural air standards 

were prepared using dried ambient air collected at the Cl site 

on Niwot Ridge (NWR), Colorado. The C01 concentrations 

were adjusted during the tank-filling procedure either by 

adding a small amount of air with a very high C02 

concentration or by dilution with air having a very low C02 

concentration. These cylinders will be used as station 

standards, station working gases, flask analysis working 

gases, and test gases. Our goal is to make all C01 

measurements with respect to natural-air C01 reference 

gases. This should eliminate the possibility of small carrier 

gas effects, which may vary from one NDIR instrument to 

another [Griffith, 1982; Bodhaine and Rosson, 1988). This 

31 
370 1987 

J :wi.~-~.I , 1' l~~ u 340 ~~ 

330 .RC l{J Ill IR Ill Alf Al. 11£ !ill' ((1 IOI [( 

e 

0. 

.e 

N 

0 

u 

330 "' 

370 

e 360 0. 

~ 350 

0 

u 340 

]0 JR< 

l[i lfl! ({I IOI lfC 

fCI Al. OCI 101 IC 

Fig. 4.2. Unselected hourly-average C01 concentrations measured 

at BRW during 1987-1 989. 

conversion will require filling - 75 cylinders per year at the 

NWR site. 

The measurement of the global distribution of 

atmospheric C01 from flask samples collected at the CMDL 

cooperative flask sampling network continued. In 1989 the 

network consisted of 29 sites (fable 4.2); two sampling sites 

in Bermuda were added to the network in 1989, one on the 

west coast (BMW) and one on the east coast (BME). 

Provisional annual mean C02 concentrations are also given 

in Table 4.2. The Pacific air sampling program.(called PAC) 

aboard the container ship Southland Star also continued in 

1989. 

The measurement of atmospheric CO was expanded to 

several more flask network sites in 1989 (see section 4.3). 

Because the CO measurements require flasks equipped with 

Teflon 0 -ring stopcocks rather than the greased stopcocks 

used for C02, we overlapped sampling in the two types of 

flasks to ensure that no offsets were introduced into the col 

time series. These field comparisons showed no significant 

offset due to the Teflon 0-rings. In fact, they resulted in 

significantly improved sample quality at several sites. 

Figure 4.3 shows the percentage of acceptable pair-samples 

(defined as having a C02 pair difference of <= 0.5 ppm), 

according to sample stopcock types, for six sites where 

overlapped sampling was conducted. 

Code 

ALT 

AMS 

ASC 

AVI 

AZR 

BME 

TABLE 4.2. Provisional 1989 Annual Mean C01 

Concentrations From the Flask Network Sites 

Station C02, ppbv 

Alen, N.W.T., Canada 355.1 

Amsterdam Island 350.5 

Ascension Island 351.7 

St. Croix, Virgin Islands 353.5 

Terceira Island, Azores I I 

Bermuda (east coast) [ J 

BMW Bermuda (west coast) [ J 

BRW Barrow, Alaska 355.1 

CBA Cold Bay, Alaska 354.4 

CGO Cape Grim, Tasmania 350.3 

CHR Christmas Island 353.3 

CMO Cape Meares, Oregon 354.4 

GMI Guam, Mariana Islands 353.6 

HBA Halley Bay, Antarctica [] 

KEY Key Biscayne, Florida 354.4 

KUM Cape Kumukahi, Hawaii 352.9 

MBC Mould Bay, Canada 355.6 

MID Midway Island 354.1 

MLO Mauna Loa, Hawaii 352.8 

NWR Niwot Ridge, Colorado 353.1 

PSA Palmer Station, Antarctica 350.9 

RPB Ragged Point, Barbados 352.9 

SEY Mah~ Island, Seychelles 352.3 

SGI South Georgia Island [ J 

SHM Shemya Island, Alaska 354.5 

SMO American Samoa 351.7 

SPO South Pole, Antarctica 350.4 

STM Ocean Station M 354.0 

SYO Syowa Station, Antarctica 349.7 

Square brackets indicate insufficient data to calculate annual 

mean. 

At Ascension, Cape Kumukahi, SMO, and Guam the 

percentage of acceptable pairs increased from -60% for the 

greased stopcock flasks to better than 80% for the Teflon 

0-ring stopcocks. The already high percentages of acceptable pairs at BRW and MLO increased only slightly. This 

suggests that the greased stopcocks produce variable 

amounu of contamination in the flasks under conditions of 

intense sunlight, high temperatures, and/or high humidity, 

leading to poor pair agreement. On the basis of these results, 

we have discontinued sampling in greased stopcock flasks at 

these sites. Also, a long-term program has been initiated to 

convert to use of larger flasks (2.5 L) equipped with Teflon 

0-ring stopcocks at all sampling sites. 

The globally averaged col growth rate determined from 

the flask network data reached a peak of -2.6 ppm yr·

1 in 

late 1987-early 1988 (Figure 4.4). This peak was followed 

by a minimum of -1.2 ppm yr1 in early 1989. The average 

growth rate for 1988 was -2.0 ppm yr·1, and for 1989 it was 

- 1.6 ppm yr·I. As reported earlier [Elkins and Rosson, 

1989), the 1987-1988 growth rate variations were consistent 

with previous El Nino/Southern Oscillation patterns. It 

appears that the changes in global atmospheric col 

concentration are even more complicated and less well 

understood than we previously believed. 

32 
GREASED 

~ 

100 

Ii Acceptable Pairs 

80 . 

60 . 

40 

20 

ASC 189l KUM 189) SMO 1891 

TEFl.011 .... 

BffN 1891 MLO 1891 GMI IHI 

Fig. 4.3. Percentage of fluk sample pain meeting the O.S ppm C02 

pair difference criterion. During 1989 samples were collected at 

these six sites in standard greased-stopcock fl11k1 and aho in flask• 

equipped with Teflon 0 -ring stopcocks. 

···························-······························-·······-········ .. ············-··--········· ' 

YEAR 

Fig. 4.4. The globally averaged C02 growth rate determined from 

the flask network data for 1981-1989. 

Figure 4.5 shows the normalized . annual-mean C02 

latitude gradients determined from the flask network data for 

1981-1987, 1988, and 1989. The north pole-to-south pole 

difference increased from -2.8 ppm (1981-1987 mean), to 

-3.6 ppm in 1988, and then to -4.6 ppm in 1989. To 

establish the robustness of this result, we plotted the 

difference between annual hemispheric means calculated 

from the flask network data (Figure 4 .6). A linear regression 

analysis reveals that the hemispheric difference is increasing 

at 0.13 ppm yr1 (cr = 0.03 ppm yr1; r : 0.84). Analysis of 

the in-situ data from the four CMDL observatories yields a 

similar result. These results suggest that a change is 

occurring in the relative magnitudes of northern and southern 

hemisphere C02 sources and sinks. 

90°5 

5 

4 

3 

2 

•+ 

0 + 

- I 

30°5 

1989 

1988 

1981 - 1987 

30°N 90°N 

! 

~'/~/r .. ·· I j I ( . ! ..r / .. · . I.·· 

;ti.··~· 

- .5 

}'/ 

1.1·· ,f··· 

SINCLFiTITUDE l 

.5 

Fig. 4.S. A comparison of lhe 1988 (x) and 1989 (0) C02 latitude 

gradients determined from flask network data, with the mean 

gradient for 198 1-1987 ( O ). The curves are third-degree 

polynomials fitted to the annual means; the three curves are forced 

through 0 at the South Pole. 

33 

e 

Q. 

~ 2 

... 0 

0 

I . 

~-· Sou•hom-• 

~ - ~ ~ ~ - ~ - ~ ~ Year 

Fig. 4.6. Differences between northern hemisphere and southern 

hemisphere annual C02 averages determined from the flask 

network data for 1981-1990. A linear regression analysis shows a 

significant trend in the interhemispheric difference of 0.13 ppm 

yr·l (a= 0.03 ppm yr1; r = 0.84). 
Preliminary results obtained using the two-dimension al 

model of Tans et al. [1989] provide no clear explanation of 

the observations. In 1988 the model requires a larger 

northern hemisphere source and in 1989 a larger southern 

hemisphere sink. Changes in known and estimated fossil 

fuel C02 emissions are too small to account for the observed 

trend in the latitude gradient. A source/sink imbalance of -1 

x 101s g C yr·l, or -20% of the annual fossil fuel C02 

emissions, is needed to produce a 1 ppm increase in the north 

pole-to-south pole difference. This startling result highlights 

our incomplete understanding of the global carbon cycle and, 

therefore, the fundamental uncertainty inherent in all 

predictions of future atmospheric C02 and greenhouse effect 

scenarios. 

4.1.2. FLASK SAMPLE METHANE MEASUREMENTS 

During 1989 the determination of the global distribution 

of atmospheric CH4 continued. Measurements of the 

atmospheric CH4 concentration were made from weekly flask 

sample s collected at 29 sites in the CMDL flask sampling 

n etwork. Provisional annual mean CH4 concentrations, 

calculated from the monthly means for each site in the flask 

network are shown in Table 4.3. Missing annual mean 

values indicate that there were insufficient data during 1989 

for that particular site. We began collecting flask samples 

from BME in February and BMW in May 1989. Azores and 

Seychelles had sampling problems that resulted in large gaps 

in the data record for 1989. Samples from Halley Bay for 

the latter part of 1989 have not yet arrived in Boulder. The 

CH4 measurement data for the past 6 years are shown in 

Figure 4.7. (Data from the high altitude sites at NWR and 

DEGREE 

s 90 JO 

0 1989 

1~60 

1988 

0 1987 

~ 1986 

1985 

1720 a 1904 

:0 1680 0. 

.9: 

.. I IG~O 0 

1600 

1560 

OI:OII.: 0111 0 u n.u>-U1 u::: >: "' U\I'.:U'1Q._ uu: "' u: 

- I. 0 - . 8 -.6 - .. - .2 

S I NE 

TABLE 4.3. Provisional 1989 Annual Mean CH4 

Concentrations From the Flask Network Sites 

Code 

ALT 

AMS 

ASC 

AVI 

AZR 

BME 

BMW 

BRW 

CBA 

CGO 

CHR 

CMO 

GMI 

HBA 

KEY 

KUM 

MBC 

MID 

MLO 

NWR 

PSA 

RPB 

SEY 

SGI 

SHM 

SMO 

SPO 

STM 

SYO 

Station 

Alert, N.W.T., Canada 

Amsterdam Island 

Ascension Island 

St. Croix, Virgin Islands 

Terceira Island, Azores 

Bermuda (east coast) 

Bermuda (west coast) 

Barrow, Alaska 

Cold Bay, Alaska 

Cape Grim, Tasmania 

Christmas Island 

Cape Meares, Oregon 

Guam, Mariana Islands 

Halley Bay, Antarctica 

Key Biscayne, Florida 

Cape Kumukahi, Hawaii 

Mould Bay, Canada 

Midway Island 

Mauna Loa, Hawaii 

Niwot Ridge, Colorado 

Palmer Station, Antarctica 

Ragged Point, Barbados 

Mahe Island, Seychelles 

South Georgia Island 

Shemya Island, Alaska 

American Samoa (Matatula Point) 

South Pole, Antarctica 

Ocean Station M 

Syowa Station, Antarctica 

CH4 , ppbv 

1777.2 

1635.6 

1647.1 

1704.4 

[) 

[I 

[) 

1790.6 

1763.3 

1635.4 

1662.9 

1756.0 

1695.7 

[I 

1721.7 

1707.1 

1779.8 

1729.5 

1696.8 

1725.3 

1633.9 

1702.5 

[I 

I I 

1770.7 

1643.2 

1633.8 

1765.2 

1634.4 

Square brackets indicate insufficient data to calculate annual 

mean. 

OF LATITUDE 

0 30 90 N 

"' m .... ,_.I: ""'' "' 0 T. <I: I:'.t UtI n.i: >:J w- N >: J..Cl ~O'.C>J 

u Q'. C) <r.~ "'" a: U UlV c.nm:..:~ 

0 . z . ~ .6 .9 I . 0 

OF LATITUDE 

Fig. 4.7. Latitudinal distribution of the annual mean CH4 concentrations for 1984-1989. Annual means are determined from flask samples. 

Data from the high-altitude sites MLO and NWR are excluded. The small circles are data from the Southland Star. 

34 
MLO are not included.) Annual mean CH4 concentrations in 

the figure are plotted as a function of sine latitude for the 

years 1984 to 1989. (Sine latitude was used to better 

represent relative global surface areas for each latitudinal 

band.) 

Three important points concerning the global distribution 

of CH4 in the troposphere are apparent in Figure 4.7. First, 

there is a strong gradient in the CH4 concentration between 

the northern and southern hemispheres, ·which reflects the 

greater CH4 source strength in the north. Second, the 

atmospheric CH4 concentration is increasing rapidly, by 

approximately 0.8% per year. Third, the CH4 concentration 

varies little from site to site in the southern hemisphere. The 

average growth rate for SPO, calculated from 12-month 

running means, is 11.9 ppbv yr1• 

In addition to weekly samples collected at sites in the flask 

sampling network, flask samples were collected aboard the 

container ship Southland Star. The flasks were collected at 

approximately 5• latitude intervals (Table 4.4). Approximately 17 samples were collected at each latitude during 

the year, at roughly 3-week intervals. The provisional 1989 

annual mean CH4 concentrations are shown in Figure 4.7 as 

the small circles. Agreement between shipboard and flask site 

samples was excellent, strongly supporting our view that the 

global distribution of CH4 in the marine boundary layer can be 

reliably evaluated through the flask network. 

4.1.3. IN-SITU METHANE MEASUREMENTS ATMLO 

CH4 measurements at MLO continued in 1989. Boulder 

personnel traveled to MLO and completely overhauled the GC 

and sampling systems. The internal switching valves of the 

GC, which can lead to poor-quality data when operating 

unsatisfactorily, were replaced. This preventative maintenance ensured an urtinterrupted stream of data. A new 

secondary standard, calibrated against the four CMDL primary 

methane standards, was put into service. 

TABLE 4.4. Provisional 1989 Annual Mean CH4 

Concentrations From the Southland Star 

Shipboard Flasks 

Latitude CH4 , ppbv 

35·s 1637.7 

3o·s 1636.8 

2s·s 1636.9 

20·s 1640.7 

15·s 1642.2 

1o·s 1649.0 

5·s 1659.3 

Equator 1666.3 

5°N 1668.8 

l0°N 1681.2 

15°N 1699.3 

20°N 1707.4 

25°N 1724.3 

30°N 1733.9 

T~e daily average CH4 concentrations for 1987-1989 are 

shown in Figure 4.8. Daily averages were calculated after 

removing data from periods when the GC was performing 

unsatisfactorily. The causes for the approximately 40 ppbv 

variations in CH4 concentration occurring on the time scale 

of days to weeks are as yet unclear. A thorough analysis of 

these variations is in progress. Provisional monthly averages 

from the in-situ measurements at MLO are shown in Table 

4.5. These monthly averages were calculated from the daily 

average CH4 concentrations and exclude data edited for 

instrument performance. During 1989 the CH4 GC system at 

MW was operating satisfactorily for 89% of the time. The 

in-situ measurements were in good agreement with the CH4 

concentrations determined in flask samples (Figure 4.9). 

4.1.4. IN-SITU METHANE MEASUREMENTS AT BRW 

In-situ measurements of CH4 at BRW continued in 1989 

with a frequency of 60 measurements per day. Daily 

averages are shown in Figure 4.10 for the period 1986-1989. 

During 1989 the CH4 GC system at BRW was operating 

1120 

nQ. 

.!?; 

r. .. 1080 

(.) 

16'0 

1911 1• I .. 

Fig. 4.8. Unselected daily average CH4 concentrations for MLO for 

1987-1989. Gaps in the data are due to inslrumenl malfunctions. 

Month 

Jan. 

Feb. 

March 

April 

May 

June 

July 

Aug. 

Sept. 

Oct. 

Nov. 

Dec. 

35 

TABLE 4.5. Provisional 1989 ln-Situ CH4 

Monthly Means at MW 

CH4 , ppbv Std. Dev., ppbv 

1706.9 8.39 

1697.9 10.11 

1693.8 10.41 

1705.0 9.60 

1697.6 10.30 

1687.6 8.19 

1681.3 4.42 

1687.2 7.47 

1703.2 9.18 

1701.0 9.16 

1705.6 13.05 

1710.0 8.68 
1850 

:0- 1800 

a. 

~ 

'I.. 

u 1750 

~ 1700 

1650 

1650 1700 1750 1800 1850 

IN-SITU CH4 (ppb) 

Fig. 4.9. Atmospheric CH4 concentrations at MLO (o) and BRW 

(t1) from flask samples versus the corresponding hourly-average 

in-situ CH4 concentration for each site. The comparison period is 

April 1987 through December 1989. The dashed line represents 

perfect agreement between the two types of measurements. 

2300 

2COO 

2100 

:0- <ooo 

~L~~ .. J~ a. 

~ 

. 

'I. 1900 

~lJ u 

~A.~J.J 1800 

1100 

1600 · - 1986 1981 1988 1989 

Fig. 4.10. Unselected daily average CH4 concentrations for BRW 

for 1986-1989. 

satisfactorily 92% of the time. The data presented in Figure 

4.10 are unselected for wind speed and direction. The large 

short-term variations in CH4 concentrations result from local 

contamination sources that affect the site during periods when 

winds blow from specific directions (for example, from the 

direction of the town). Selected monthly averages (calculated 

from daily-average CH4 concentrations) are listed in Table 4.6. 

These CH4 values are assoc iated with wind speeds greater than 

3 m s·l and within a sector defined as 20' to 11 O'. On the 

basis of CMDL meteorological data from BRW, 1989 was an 

anomalous year when winds were predominantly from the 

west during January, February, and March. Agreement 

between the flask samples collected at BRW and the in-situ 

measurements was excellent, as shown in Figure 4.9. 

36 

TABLE 4.6 . Provisional 1989 In-Situ CH4 

Monthly Means at BRW 

Month CH4 , ppbv Std. Dev., ppbv 

Jan. 1790.5 • 

Feb. 179 1.1 10.94 

March 1795.6 18.33 

April 1780.2 6.05 

May 1766.8 6.53 

June 1758.1 IO. I I 

July 1777.8 27.79 

Aug. 1814.8 54.63 

Sept. 1785.7 39.33 

Oct. 1787.9 20.96 

Nov. 1801.3 27.89 

Dec. 1797.7 8.21 

•This concenlration represents only day of this month. 

standard deviation was not calculated. 

4.1.5. FLASK SAMPLE CARBON MONOXIDE 

MEASUREMENTS 

The 

In collaboration with the Halocarbons Group, we have 

established a set of 17 gravimetric reference gas mixtures for 

use in the measurement of atmospheric CO. The mixing 

ratios of the gravimetric standards range from 25 to 1003 

ppb (parts per billion by mole fraction) (Table 4.7). This 

concentration range covers that present in the background 

troposphere (approximately 50 to 250 ppb), and also those 

levels found in remote locations affected by anthropogenic 

activities such as biomass burning. The standards are 

contained in 5.9-L aluminum cylinders with brass fittings. 

Standards with CO concentrations reflecting those in the 

atmosphere were prepared from one of three highconcentration "parents." Two parents were prepared 

gravimetrically from 99 .97% CO to have CO concentrations 

of -250 ppm, from which a total of 14 lower-concentration 

standards were prepared. In addition, we prepared three 

low-concentration standards using a NIST SRM (CO 

concentration of 9.7 ppm) as the parent. Comparison of 

standards derived from the gravimetric standards with those 

derived from the SRM show no statistical difference between 

the two scales. Therefore, all low-concentration standards 

were pooled to define a new reference scale for CO (Figure 

4.11 ). 

The CO scale defined by the gravimetric standards was 

used to create a set of six internally consistent secondary 

standards. These secondary standards, all of natural air, 

were obtained at NWR and are contained in 29-L aluminum 

cylinders. The standards range in concentration from 

approximately 100 to 200 ppb (Table 4.8). Intercomparison 

of the CO content of the air contained in the 29-L cylinders 

has shown that these cylinders are stable with respect to CO 

for at least 2 years. However, we found the CO content of 

the primary standards to be increasing at rates ranging from 

1 to 3 ppb yr·l. Comparison of CO reference scales defined 

with and without the standards exhibiting CO growth showed 

no significant difference. Therefore, although the useful 
TABLE 4.7. Primary CO Standards 

Cylinder ID 

FF31482 

FF31476 

FF31460 

FF32804 

FF3 1459 

FF3 1474 

FF3 1475 

FF32780 

FF3 1450 

FF32792 

FF31451 

FF32788 

FF32805 

FF32813 

FF32799 

FF31488 

FF32819 

Date• 

April 8, 1988 

April 8, 1988 

April·?, 1989 

April I 0, 1989 

April I 0, 1989 

April 17, 1989 

July 7, 1989 

July 6, 1989 

July 6, 1989 

July 6, 1989 

Aug. 2, 1989 

Aug. 2, 1989 

Aug. 3, 1989 

Aug. 4, 1989 

Aug. 4, 1989 

Aug. 6, 1989 

Oct. 9, 1989 

*Date of standard preparation. 

CO Mole Fraction, 

ppb 

45.22 

110.8 

107.1 

145.1 

199.1 

128.1 

76.59 

344.0 

49.98 

166.0 

25.25 

254.1 t 

74.851 

141.9t 

Blank* 

291.5 

1002.9 

!These standards were prepared using a NIST SRM as the parent. 

All other standards were prepared from one of two high-concentration 

CO standards prepared by gravimetric methods in our laboratory. 

*The blank was prepared using Ultrapure air as the parent. 

2000 

1750 

<II 1500 \/) 

c 

0 

a. 

\/) 

<II 1250 a:: 

0 

<II 1000 .._ 

<( 

"O 

<II 

N 750 0 

E 

0 

z 500 

250 

0 

0 200 400 600 800 1000 

CO Concentrotion ( ppb) 

Fig. 4.11. Chromatographic peak area response versus CO concentration for all atmospheric-level gravimetric standards. The solid 

circles are standards prepared from one of two "parents" by gravimetric methods in our laboratory; the inverted triangles represent 

standards prepared using a NIST SRM as the parent. Each point 

represents the mean area response of al least 15 aliquou, normalized to 

the air contained in a 29-L cylinder, which is believed to be stable with 

respect to CO over time. The standard error of the mean is contained 

within the size of the point. The normalization procedure removes small 

effects due to both short- and long-term detector variations. The solid 

line represents the linear least squares fit to the data. 

37 

TABLE 4.8. Secondary CO Standards* 

Cylinder ID Ai rt Date* CO Mole Fraction, 

ppbf 

AAL-17262 NWR Nov. 1987 113.9 ± 1.5 

AAL-17268 NWR Nov. 1987 127.7 ± 2.0 

AAL-17269 NWR Nov. 1987 118.5 ± 0.6 

CC68734 NWR Dec. 1988 159.7 ± 1.5 

CC61344 NWR Dec. 1988 181.5 ± 1.5 

CC64035 NWR Nov. 1989 113.9 ± I.I 

*Concentrations for the secondary standards were calculated using 

the empirical relationship between area response and CO concentration determined using the gravimetric primary standards. 

!Air used for the reference gas. NWR indicates that the air was 

collected by our lab at Ni wot Ridge, Colorado. 

*Date of the final fill of the cylinder. 

fCO concentrations arc referenced against the NOAA/CMDL 

gravimetric standards. The quoted uncertainty is one standard 

deviation. 

lifetime of some cylinders may be limited, CO growth has 

not affected the overall scale defined by the set of standards. 

We compared our standards with two certified, NISTtraceable CO standards purchased from Scott-Marrin, Inc. 

(CO concentrations of these standards were 0.49 ppb and 

0.98 ppb). The concentrations assigned these standards by 

the manufacturer agreed to within 3% with the concentrations that we calculated with reference to our CO scale. We 

also compared our reference scale with a CO standard 

maintained at CSIRO, which is tied to the sc ale developed 

and distributed by OGC. One cylinder of natural, dried air, 

having an unknown CO concentration, was calibrated by 

both laboratories. Results of this intercomparison showed 

that CO concentrations referenced against the standard scale 

developed at CMDL are 25% greater than those calculated 

using the CSIRO standard. This result agreed well with that 

of Weeks et al. [1989), who found that the concentration of a 

CO standard, when referenced to the OGC scale, was 22% 

lower than that calculated against a NIST-traceable standard. 

The measurement of CO concentrations in flask samples 

collected at BRW, NWR, and SMO continued in 1989. In 

addition, we began measuring CO levels at the following 

CMDL cooperative flask sampling network sites (the date of 

the first sample is given in parentheses): Ascension Island 

(02/02); Cape Kumukahi (03/07); MLO (07 /07); Guam 

(09/1 O); and Christmas Island (25/12). These sites were 

chosen on the basis of several criteria including latitude, 

sample transit time between the site and Boulder (sample 

contamination is associated with long storage time), and 

scientific value (i.e., samples from Ascension Island, at 

nearly the same latitude as SMO, provide information on 

longitudinal variations in CO levels). CO measurements 

were made only in glass flasks fitted with Teflon 0-ring 

stopcocks. CO was measured at all sites in flasks of 0.5-L 

volume (except Christmas Island where only 3 -L Teflon 
0 -ring flasks were used); al Cape Kumukahi, BRW, and 

SMO, CO was also measured in flasks having volume of 

approximately 3 L. 

The record of monthly mean CO concentrations 

determined in flasks filled at BRW during 1989 is presented 

in Figure 4.12. The seasonal concentration variations 

observed at this site are typical of the northern hemisphere: 

higher concentrations were found in winter, lower concentrations were observed in summer. This seasonal cycle, in large 

part, reflects variations in hydroxyl radical [e.g .. Logan et 

al., 1981]. As noted in section 4.2, meteorological 

conditions at BRW were unusual during the winter of 1989 

in that winds were predominantly from sectors not 

considered to transport "background" air to the sampling site. 

Local contamination may have elevated CO concentrations 

above background levels; however, local CO sources are not 

believed to drive the observed seasonal variations. They 

could, however, affect the magnitude of the seasonal 

concentration amplitudes. The high CO concentrations 

observed in January reflect, in part, a period of very high CO 

concentrations (up to 270 ppb) associated with an Arctic 

high-pressure system situated over BRW during the middle 

of the month. 

4.2. SPECIAL PROJECTS 

4.2.1. AGASP III 

On six aircraft flights during AGASP III, 186 air samples 

were collected throughout the Arctic troposphere and lower 

stratosphere in glass flasks equipped with Teflon 0-ring 

stopcocks. These flask samples were analyzed for concentrations of C02 by NDIR analysis; CH4 by GC/FID; and CO by 

a mercuric oxide reduction technique. 

The concentrations of the three gases varied significantly 

both horizontally and vertically. Elevated trace gas 

concentrations were found in layers with high anthropogenic 

aerosol concentrations (Arctic haze). The data from flight 

306 are shown as an example (Figure 4.13). The 

concentrations of C0 2, CH4, and CO were highly correlated 

during all flights. A linear regression of CH4 versus C02 for 

pooled data from all flights yielded a correlation coefficient 

(r2) of 0.88 with a slope of 13.5 ppb CH4/ppm C01 (n = 186). 

For CO versus C01 a pooled linear regression gave r2 = 0.91 

with a slope of 12.4 ppb CO/ppm C01 (n = 183). C01, CH4, 

and CO also exhibited mean vertical gradients with slopes of 

-0.56 ppm knrl, -6.6 ppb k.m·l, and -5.79 ppb km·1, respectively. 

Since the C02 variations observed in the Arctic 

atmosphere during winter are due lo variations in the 

transport of anthropogenic col from lower latitudes, these 

results suggest that the CH4 and CO data might be similarly 

interpreted. Using reliable estimates of C02 emissions for 

various source regions, it should be possible to estimate 

corresponding regional CH4 and CO sources using the 

measured CHJC02 and CO/C01 ratios. Such estimates are 

important in light of the large uncertainties in current 

estimates of global CH4 and CO emissions. 

0 '--~~-'---'~-'-~'----'-~......____.L--L..~.J.._--'L-_J 

Jon Feb Mar Apr Moy Jun Jul Aug Sep Oct Nov Oec Jan 

Time (months) 

Fig. 4.12. Monthly mean CO concentrations determined in flask 

samples collected at BRW during 1989. Each point represents the 

mean of about four weekly samples, with at least two aliquots 

analyud from a single sample. Instrument precision on replicate 

samples was always better than 1 %. The error bars represent one 

standard deviation around the mean. 

4.2.2. SHIPBOARD SAMPLING 

During January and February, the National Marine 

Fisheries Service conducted its first expedition to the 

Antarctic using the NOAA ship Surveyor. The primary 

purpose of the cruise was to provide fisheries data for the 

U.S. delegation that advises the Convention for the Conservation of Antarctic Marine Living Resources, an agency of 

the Antarctic Treaty system. The Carbon Cycle Group used 

this opportunity lo make continuous measurements of C01 in 

surface waters of Lhe Scotia Sea area of the southern oceans 

[Waterman, 1989]. The expedition made stops at Palmer 

Station, Antarctica, and at Bird Island, South Georgia 

(remote sampling sites in the flask network). 

The shipboard measurement system was fully operational 

before departure from Punta Arenas, Chile. A nearly 

complete record of both atmospheric C01 concentrations and 

pC01 in the surface ocean was obtained along the entire Leg 

I track. Preliminary examination of pC01 values shows 

areas of both undersaturation and supersaturation, with 

sometimes sharp boundaries. These conditions were first 

observed in the Drake Passage crossing. The total area 

surveyed represents a small portion of the southern oceans 

and should not be construed as representative of the whole 

region. 

38 
351 352 353 354 355 356 357 358 359 360 361 362 363 364 C02 (ppm} 

.μ 

Q) 

Q) 

u... 

"'CJ 

c 

ftl 

(I) 

:::J 

0 

.c. 

t28 

26 

24 

22 

20 

18 

16 

14 

12 

10 

8 

6 

4 

2 

-&---"'>E) 

HAZf LAYEii - -

---- ~- - -~ 

~ -e..... 

;::o 

~: 1620 1640 1660 1680 1700 1720 

G---

---

1740 

a CH4 

A C02 

0 co 

---

-i;i 

\ 

\ 

,...E 

0:-- - - - - -G 

bl 

\ 

l 

1760 1780 1800 CH4 (ppb} 

~~-l- -l- -l---_J~- -L.. _JL-.. ~~-L--~---1~~_.i.__ ___J 

150 170 190 210 230 250 270 290 310 330 350 370 co (ppb} 

Fig. 4.13. Concentrations of C02, CH4, and CO measured in fla sk samples collected during flight 306 (March 21 1989) as part of the 

AG ASP ill mission. ' 

4.3. REFERENCES 

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

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

NOAA Air Resources Laboratory, Boulder, CO, 1988. 

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

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

NOAA Air Resources Laboratory, Boulder, CO, 1989. 

Griffith, D.W.T., Calculations of carrier gas effects in nondispersive 

infrared analyzers, I, Theory, Tel/us, 34, 376-384, 1982. 

Komhyr, W.D., T.B. Harris, L.S. Waterman, J.F.S. Chin, and K.W. 

Thoning, Atmospheric carbon dioxide at Mauna Loa Observatory, I, NOAA Global Monitoring for Climatic Change 

measurements with a nondispersive infrared analyzer, 

1974-1985, 1. Geophys. Res., 94, 8533-8547, 1989. 

Logan, J.A., M.J. Prather, S.C. Wofsy, and M.B. McE!roy, 

Tropospheric chemistry: A global perspective, J. Gtophys. Res., 

86, 72 10-7254, 1981. 

39 

Tans, P.P., T J. Conway, and T. Nakazawa, Latirudinal distribution of 

the sources and sinks of atmospheric carbon dioxide derived from 

surface observations and an atmospheric transport model, J. 

Geophys. Res., 94, 5151 -5172, 1989. 

Thoning, K.W., P.P. Tans, and W.D. Komhyr, AUnospheric carbon 

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

GMCC data, 1974-1985, J. Geophys. Res., 94, 8549-8565, 1989. 

Waterman, L.S., Monitor air and surface water C02 content, Leg I, in 

United States Antarctic Marine Living Resources Program, Cruise 

Report AMIR 8901, edited by Roger Hewiu, pp. 9-10, NOAA 

National Marine Fisheries Service, La Jolla, CA, 1989. 

Waterman, L.S., D.W. Nelson, W.D. Komhyr, T.B. Harris, K.W. 

Thoning, and P.P. Tans, AUnospheric carbon dioxide 

measurements at Cape Matatula, American Samoa, 1976-1987, J. 

Geophys. Res., 94, 14817-14829, 1989. 

Weeks, I.A., I.E. Galbally, P.J. Fraser, and G. Matthews, Comparison 

of the carbon monoxide standards used at Cape Grim and 

Aspendale, in Base/int 1987, edited by B.W. Forgan and G.P. 

Ayers, pp. 21-25, CSIRO, Melbourne, Australia, 1989. 
5. Ozone Group 

S.J. 0LTMANS (Editor), W.D. KOMHYR, R.D. GRASS, R.D. EVANS, G.L. KOENIG, R.K. LEONARD, AND D.H. QUINCY 

5.1. CONTINUING PROGRAMS 

5.1.1. TOTAL OZONE OBSERVATIONS 

Routine total ozone observations were made with Dobson 

spectrophotometers during 1989 at 16 stations that make up 

the U.S. total ozone station network (fable 5.1). Of all the 

stations, five are operated by CMDL personnel, four are 

operated by NWS, three are domestic cooperative stations, 

and four are foreign cooperative stations. Ozone measurements at the Tallahassee, Florida, Dobson instrument station, 

operated by Florida State University, were terminated 

November 30, 1989. Plans are being made to transfer the 

operation of this program to NWS at Tallahassee, Florida. 

Table 5.2 lists provisional monthly mean total ozone 

amounts measured at the various stations during 1989. 

The mean trend in total ozone over the United States, 

derived from provisional total ozone amounts measured from 

1980 through mid-1990 at Bismarck, Boulder, Caribou, 

Fresno, Nashville, Tallahassee, and Wallops Island, is 

-0.34% yrl. This value compares favorably with the trend 

of -0.46% yr1 derived from corrected TOMS satellite data 

TABLE 5.1. U.S. Dobson Ozone Spectrophotometer Station Network for 1989 

Station Period of Record Instrument No. Agency 

Bismarck, ND Jan. 1, 1963-present 33 NOAA 

Caribou, ME Jan. 1, 1963-present 34 NOAA 

Wall ops Is., VA July 1, 1967-present 38 NOAA; NASA 

SMO Dec. 19, 1975-present 42 NOAA 

Tallahassee, FL May 2, 1964-Nov. 30, 1989 58 NOAA; Florida State University 

Boulder, CO Sept. 1, 1966-present 61 NOAA 

Poker Flat, AK March 6, 1984-present 63 NOAA; University of Alaska 

Lauder, New Zealand Jan. 29, 1987-present 72 NOAA; DSIR 

MLO Jan. 2, 1964-present 76 NOAA 

Nashville, TN Jan. 2, 1963-present 79 NOAA 

Perth, Australia July 30, 1984-present 81 NOAA; Australian Bureau Meteorology 

SPO Nov. 17, 1961 -present 82 NOAA 

Haute Provence, France Sept. 2, 1983-present 85 NOAA;CNRS 

Huancayo, Peru Feb. 14, 1964-present 87 NOAA; IGP 

BRW June 6, 1986-present 91 NOAA 

Fresno, CA June 22, 1983-present 94 NOAA 

TABLE 5.2. Provisional 1989 Monthly Mean Total Ozone Amounts (m-atm-cm) 

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

Bismarck, ND 352 362 364 380 353 347 309 313 303 295 307 342 

Caribou, ME 357 366 398 423 365 355 357 335 312 310 320 385 

Wallops Is., VA 320 315 341 374 377 333 337 322 205 205 298 310 

SMO 263 248 252 256 254 267 265 265 278 271 272 267 

Tallahassee, FL 285 296 296 323 323 296 299 294 284 272 

Boulder, CO 321 313 329 339 341 335 307 298 289 282 287 317 

Poker Flat, AK 374 372 355 323 300 292 

Lauder, New Zealand 290 286 280 271 298 319 340 358 337 370 339 308 

MLO 264 277 280 301 309 268 282 277 279 267 253 248 

Nashville, TN 297 308 323 352 350 342 319 317 301 296 295 303 

Perth, Australia 287 276 278 278 284 295 313 324 334 339 320 301 

SPO 286 269 263 245 268 259 161 235 303 

Haute Provence, France 327 355 342 395 360 353 330 323 310 287 299 312 

Huancayo, Peru 262 262 252 256 254 253 258 259 273 262 264 259 

BRW 420 439 376 345 327 311 301 

Fresno, CA 319 319 316 333 338 327 313 311 302 290 274 279 

40 
obtained from late 1979 through mid-1990 in a zonal band 

centered at 40'N latitude (R. Stolarski, NASA Goddard 

Space Flight Center, private communication, 1991). At 

MLO and SMO in the equatorial Pacific, ozone decreased 

during 1976-1987 at rates of -0.27% yr1 and-0.41% yr', 

respectively (Figure 5.1). (Prior to 1976, ozone at MLO had 

been increasing at 0.34% yr· 1.) However, since mid-1988, 

ozone amounts at these locations have increased. Essentially 

zero ozone trends are computed at MLO and SMO from 14 

years of data ending in August 1990 (Figure 5.1). 

Allhough stratospheric ozone amounts are expected to 

decline as more and more anthropogenic CFCs reach the 

stratosphere, the pattern of ozone changes described here 

suggests that other mechanisms may also be at work to cause 

the changes. Times of enhanced UV flux associated with the 

11 -year solar cycle may increase column ozone amount by 

0.7-2.0% [Watson et al., 1988]. Recent work [Komhyr et al., 

1991] suggests that long-term changes in atmospheric 

circulation processes resulting from tropical sea surface 

temperature changes may also lead to approximately decadal 

trends in ozone. 

Figure 5.2 plots mean total ozone amounts measured at 

South Pole during October 15-31 of 1962-1989. (MidOctober is when Dobson spectrophotometer total ozone 

observations first become possible each year at South Pole 

following the polar night.) Note that the 1989 mean value 

approached that of 1987, which to date has been the record 

low. The 1988 ozone depletion was considerably less 

severe; the mean October 15-30 total ozone amount was 

comparable with values that occurred several times prior to 

1978. 

5.1.2. DOBSON SPECTROPHOTOMETER CALIBRATIONS 

During 1989 CMDL continued its program of upgrading 

and calibrating Dobson ozone spectrophotometers of the 

global Dobson instrument network. Instruments calibrated in 

1989 are listed in Table 5.3. In March 1989 the Pretoria, 

South Africa, instrument no. 89 was received in Boulder for 

recalibration. It was modified with U.S. solid-state 

electronics, optically aligned, recalibrated, and returned to 

Pretoria. All calibrations were performed relative to World 

Standard Dobson spectrophotometer no. 83 . 

Provisional calibration of the four U. S. Dobson 

instrumenlS showed them to be out of calibration as follows: 

no. 63, - 0.2%; no. 65, +0.5%; no. 92, +1.5%; and no. 94, 

+1.1%. A positive sign indicates that the instrument was 

measuring ozone values too high. Japanese instrument no. 

116 was found to be out of calibration by +1.05%. No 

calibration check was made on the Pretoria instrument, since 

it was not operational when it arrived in Boulder, and it had 

not been used in Pretoria for 16 years. 

5.1.3. UMKEHR OBSERVATIONS 

Umkehr observations with automated Dobson ozone 

spectrophotometers were continued during 1989 in Boulder, 

Colorado (40'N, 105'W); Mauna Loa, Hawaii (20'N, 

41 

~~ 

~~ 

~o 

o"~ 

< ' MAUNA LOA --- -o. '""" .,,,, ~' "'. Q o --0, Tt&D. -OJ.4 2 171 IYI' 

... 1' 1-~-..,--r--,--..---.--...-~--,--r--,--....---.--..----l 

76 78 80 82 8~ 86 88 90 

YEAR 

Fig. 5.1. Ozone trends al MLO and SMO for 1976-1987 (dashed 

lines) and August 1, 1976-August 31, 1990 (solid lines). The trends 

are least-squares regressions fitted to the ozone monthly anomalies. 

Indicated uncertainties are 95% confidence limits (t-statistic). 

5 

e. 300 -

w 

z 

0 

N 

0 

_J 

~ 

~ 200 

100 

1960 1970 1980 1990 

YEAR 

Fig. 5.2. South Pole October 15-31 mean total ozone amounts in 

Dobson units for 1962-1989. 

TABLE 5.3. Dobson Spectrophotometers Calibrated in 1989 

Country Station Instrument No. 

South Africa Pretoria 89 

Japan Tateno 116 

United States Poker Flat 63 

United States Boulder 65 

United States Barrow 91 

United States Fresno 94 
156°W); Haute Provence Observatory, France (44'N, 6'E); 

Poker Flat, Alaska (65°N, 148'W); Perth, Australia (32' S, 

l l6°E); and Lauder, New Zealand (45'S, 169'E). A total of 

1242 ozone profiles were obtained. All provisional data 

have been archived at the WMO World Ozone Data Centre, 

Atmospheric Environment Service, Downsview, Canada. 

Umkehr observations were also made at Huancayo, Peru, 

but manually. Operation of the instrument in the automatic 

mode failed, and because of political turmoil in the country, 

replacement of electronic parts has not been possible. 

Communications have become a problem between the 

observatory and Boulder. 

5 .1.4. TROPOSPl-IERlC OZONE 

The first year of surface ozone observations from three of 

the AEROCE sites in the North Atlantic provide a first 

glimpse of the pattern of ozone behavior in lhis region. 

Although only a few months of data have been obtained at 

Mace Head, Ireland, nearly a year's data have been obtained 

at Barbados and more than a year's data at Bermuda. 

Because the AEROCE sites are surrounded by several major 

continents, it will eventually be possible, using the 

information from a number of the chemical measurements 

being made at the sites, to decipher the role of anthropogenic 

emissions on the ozone distribution in this region. 

Several important characteristics of the ozone distribution 

at Bermuda and Barbados can be seen even in the short 

available record. At Bermuda there is a prominent seasonal 

cycle (Figure 5.3) with a spring maximum and late summer 

minimum. During the spring peak season hourly average 

mixing ratios occasionally exceeded 75 ppb, and day-to-day 

fluctuations were large (Figure 5.4). This pattern appears to 

reflect rather sudden influxes of ozone and then a gradual 

decay before the appearance of another pulse of high ozone. 

f 

'" '" 

6 1 

llOllTH 

10 11 12 

Fig. 5.3. Ozone volume mixing ratio by month at Bermuda for 

1989. The X's denote mean values, the dots indicate median values, 

the boxes represent the middle 50th percentiles, and the bars, the 

middle 90th percentiles. 

0 

.... 

"' <D 

CD o . a. <D 

a. 

_.,., _ o"' 

I- 0 

a: "' 0:: 

(!) "' ~ 

~~ x 

2= 

~ g ::> 

~~ > 

w~

z 

N- o"' · 

0 

5 I 0 I 5 20 25 30 

DAY 

Fig. 5.4. Hourly ozone volume mixing ratios in pans per billion at 

Bermuda for May 1989. 

Such fluctuations are on a time scale similar to synopticscale meteorological disburbances. During the summer, 

however, the pulses of ozone are smaller and less frequent 

and there is a general overall decline in the ozone 

concentration. This reflects the dominating influence of the 

Bermuda high-pressure system that prevents weather systems 

from the north and west from reaching Bermuda. Under the 

influence of high pressure, it appears that ozone is gradually 

destroyed as hydroxol increases and nitrogen oxides remain 

low. 

A diurnal cycle is evident at Barbados (Figure 5.5) with 

maximum concentrations in the morning and minima in the 

afternoon. This pattern is very similar to that at SMO 

(14 'S), which is the same distance south of the equator as 

Barbados (14 'N) is north of the equator. This "reverse" 

diurnal cycle appears to be typical of the tropical marine 

lower atmosphere [0/tmans, 1981; Johnson et al., 1990] 

where odd nitrogen (NO, = NO + N02) concentrations arc 

low. 

As at Bermuda, the seasonal surface ozone variation at 

Barbados is also prominent (Figure 5.6), with the ozone 

peaking early in the year. Again the pattern is very similar 

to that at SMO, but the maximum at Barbados is in January 

and at SMO in July. The minima occur also 6 months apart. 

The amplitude of the seasonal cyce at the two sites is nearly 

identical. Barbados, however, has an annual mean ozone 

concentration that is 7.5 ppb (-50%) higher than the SMO 

annual mean. This is in keeping with the overall pattern of 

higher tropospheric ozone concentrations in the northern 

hemisphere. 

42 

Surface ozone monthly means for the four CMDL sites 

with longer observational records are shown in Figure 5.7. 
"' 

a; M· 

a... 

a... 

a -"' 

...... 

a: - - Cl: 

x 

w"' :E ' :::> 

_J 

OM 

>' 

I 2 3 1 5678910 111 213 1115 16 17 181920212223 21 

LST 

Fig. 5.5. Average ozone volume mixing ratio deviations from daily 

means for each hour of the day at Barbados, derived from nearly 

one year's observations. Symbols are as in Fig. 5.3. 

0 

.., 

<II 

a: 

Ol 

c~ 

~ .g_ 20 ~ ..9- Q) 

§ 10 

0 

> o I 

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

Month 

Fig. 5.6. Daily surface ozone volume mixing ratios in parts per 

billion al Barbados for 1989. 

Superimposed on the plots are linear-least-squares ozone 

trend lines derived from fits to plots of surface ozone 

monthly anomalies. At MLO the last 6 years of average 

concentrations have markedly slowed the long-term surface 

ozone growth rate. The positive ozone trend of nearly 1 % 

yr 1 at BRW is the result mainly of large increases in ozone 

with time during summer and autumn months, as discussed 

in last year's report [Elkins and Rosson, 1989). At SMO the 

strong temporal decrease in surface ozone that has occurred 

during summer months has been offset by modest ozone 

increases during the remainder of the year. At SPO the 

marginally significant overall decrease in surface ozone is a 

result of the strong decrease during summer months, a time 

of the seasonal minimum in tropospheric ozone. 

43 

40 

I i I I I 

35 Barrow 0.91!:0.35% yr·! 

30 

25t=-~-ttt-tfl-l+f-i:H-HJ:W.l~H-+~~Ffd-H-1 

20 

15 

10 

:C Mauna Loa 0.43 !: 0.34°/o yr 1 

..s 35 

30 

25 

20 

20 

15 

10 

i--~~~~~~t:-+-l+W-4+-l-+-~a.+a.+~-'r-i~4-H-..... 

25 

20r=-~~-.:i=-tff=-t:1~H-+.++H+.f4.l.:W~,,ff-:;f:l:i~ 

15 

10 

5 I I II I I 

70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 

Year 

Fig. 5.7. Monthly mean surface ozone partial pressures at BRW, 

MLO, SMO, and SPO. Trend lines (dashed) are linear-least-squares 

fits to monthly ozone anomalies. Solid lines represent the mean 

ozone partial pressures for the periods of record. Uncertainties in 

the indicated trend estimates are 95% confidence limits. 

5.1.5. 0ZONESONDE OBSERVATIONS 

Weekly measurements of atmospheric ozone vertical 

distribution with ECC ozonesondes were continued at Hilo, 

Hawaii. Ozone soundings were also made at Boulder, 

Colorado, and SMO, but at irregular intervals, yielding about 

20 profiles at each site. ECC ozonesondes were also flown 

at SPO [Komhyr et al., 1990a]. 

The 1989 observations at SPO were a continuation of a 

program that began in 1986 to study Antarctic springtime 

ozone depletion. A total of 60 balloon ozonesonde 

soundings were made. The instruments were flown once per 

week, except during the months of September-Nove mber 

when frequency was increased to 2-3 soundings per week. 

Figure 5.8 compares ozone profile data for August 20 or 

21, 1987-1989, with that for October 9 or 10, 1987-1989. 

The August profiles, having total ozone amounts of 263-272 

DU, and shown in Figure 5.8 only for the region of the 
1 ·SOUTH POLE I 

-ID 

:i::: 

a: C26Jl 25 :::J 

I.fl 

lQ. _ 

--- a: 20 

Cl. 

s 

100 

AOO 87 <272) 15 

200 -e9 CX:T 87 ( 12 7) 10 

10 CX:T 88 ( 197) 

9 89 C I 36 > I 

----- 5 

so 100 150 200 250 

PARllAL PR[SSUR[ or OZONE IMBl 

300 -90 -70 -$0 -30 - 10 

TEHPERATURE I 'Cl 

10 JO 

Fig. 5.8. South Pole ozone and air temperature profiles, al times (-October 9) in 1987-1989, of Antarctic springtime maximum ozone 

destruction. The August profiles, shown for comparison, indicate the amount of ozone present in the region of the normal stratospheric ozone 

maximum prior 10 onset each year of the ozone depletion process. 

Antarctic stratospheric ozone maximum, represent the ozone 

distributions at SPO at 190-30 mb prior to onset each year of 

the Antarctic springtime ozone .!epletion phenomenon. 

Stratospheric ozone depletion at South Pole generally begins 

in late August or early September and reaches a maximum 

October 9-10, at which time the minimum total ozone 

amount for the year is observed. 

Note from Figure 5.8 that the degree of ozone depletion 

in October 1989 approached that in October 1981-- a year 

of record depletion. Almost total destruction of ozone 

occurred in the 100-50 mb region. Minimum observed 

total ozone amounts were 127 and 136 DU on October 9 in 

1987 and 1989, respectively. In contrast, ozone depletion 

in 1988 was considerably less severe, the October 10 total 

ozone value being 197 DU. Breakdown of the Antarctic 

circumpolar vortex and ozone recovery began early in 

December in 1987, about 2 weeks earlier in 1989, but early 

in November in 1988. 

5.1.6. VALIDATION OF SATELLITE INSTRUMENT 

OZONE DATA 

CMDL maintains and operates World Standard Dobson 

spectrophotometer no. 83, which was designated in 1980 by 

the WMO as the primary standard Dobson spectrophotometer 

44 

for the world. The instrument was established as a standard 

for total ozone measurements in the United States in 1962. 

Long-term total ozone measurement precision of the 

instrument has been maintained throughout the years to ±0.5% 

[Komhyr et al., 1989]. Since the mid 1970's, the instrument 

has been used extensively to calibrate Dobson ozone 

spectrophotometers of the global Dobson instrument 

network. 

Total ozone data, obtained with instrument no. 83 at MLO 

since 1979 while calibrating the instrument, have been used 

to validate TOMS and SBUV satellite instrument ozone data 

obtained aboard the Nimbus 7 satellite [McPeters and 

Komhyr, 1991]. Results are shown in Figure 5.9 where the 

TOMS and SBUV ozone data are compared with data from 

instrument no. 83 as well as from 39 select Dobson stations 

of the global Dobson station network. Note that relative to 

instrument no. 83, the TOMS instrument calibration has 

drifted 7% in 10 years. The cause has been degradation of a 

diffuser plate aboard the Nimbus satellite that is periodically 

viewed by the TOMS and SBUV instruments. 

5.1.7. STRATOSPHERIC WATER VAPOR 

A continuing program of approximately monthly balloon 

frost-point hygrometer soundings at Boulder since 1981 has 
•. 

. -.:-. ......----·------ . --... - ----- TOMS· 183 

TOMS - 39 slalions - • 

u. 2 !!, 

:: I z 

w 

g 0 

w 

"- . 1 

·2 

·3 

··~- ~':'._ . 

SBUV • 39 slalions "'-

"

4 

79 80 81 82 83 84 85 86 87 88 89 90 91 

YEAR 

Fig. 5.9. Calibration drifts of TOMS and SBUV satellite ozone 

inslruments relative to the calibration levels of World Standard 

Dobson instrument no. 83 (183) and of 39 foleCt Dobson instrumenls 

of the global Dobson instrument network. Results were derived 

from total ozone observations made during satellite and groundbased instrument comparisons. The version 5 algorithm was used in 

processing 1he satellite data. 

delineated several important features of the seasonal and 

long-term behavior of upper tropospheric and stratospheric 

water vapor [Bodhaine and Rosson, 1988; Elkins and 

Rosson, 1989). Based on data from 1981-89, average water 

vapor volume m1xmg ratios at selected atmospheric 

pressures between 250 and 17 mh are shown in Table 5.4. 

Note the rapid drop in water vapor across the tropopause, 

the minimum near 80 mb, and the gradual increase in mixing 

ratio with altitude in the stratosphere. 

Since the launch of the SAGE II satellite sensor in 1984, a 

number of balloonbome, frost-point hygrometers have been 

flown to provide correlative stratospheric water vapor 

profiles for satellite measurement validation. As part of this 

effort, balloon measurements have been made in Boulder, 

Colorado; Laramie, Wyoming; Fairbanks, Alaska; and Pago 

Pago, American Samoa. An example of correlative 

measurement profiles is shown in Figure 5.10. The 

TABLE 5.4. Stratospheric Water Vapor Mean Volume 

Mixing Ratio for 1981-1989 at Boulder, Colorado 

Pressure, 

mb 

250 

120 

80 

50 

40 

25 

17 

Approximate Mean H20-Vapor Mixing Ra1io 

Altitude, Mixing Ratio, Std. Dev., Number 

km ppmv ppmv of Obs. 

10.5 

15.0 

17.5 

20.5 

22.0 

25.0 

27.5 

68.27 

3.97 

3.61 

4.01 

4. 14 

4.27 

4.35 

52.53 

1.35 

0.44 

0.32 

0.29 

0.30 

0.33 

82 

83 

83 

80 

78 

72 

33 

•. . . ~ SAG( 11 

JI OCT 85 IJJBZ 

LAI. 11.6 Lll·1G. • 101 .5 

• BC• .OfR JI OCT 8$ 16lii! t Al. 10.0 1111.G. • iOS. 2 

' s 6 1 e VOLUll[ MI x ING RAT IOI rr11v I 10 

Fig. 5.10. Stratospheric water vapor mixing ratio profiles derived 

from SAGE II satellite observations (solid line) and from balloonborne, frost-point hygrometer soundings at Boulder (dashed line). 

satellite-obtained profile is a preliminary one; final 

corrections for interference from aerosols and ozone will he 

applied later. The overall agreement, however, appears to be 

very good. The difference in the layer 19-28 km may result 

from a partially unaccounted for interference by ozone in the 

satellite profile retrieval algorithm. 

In January 1989 an experiment was conducted at Alert, 

Northwest Territories, Canada, to investigate the formation 

and properties of polar stratospheric clouds (PSCs) during 

the Arctic night [Rosen et al., 1989). The presence and 

optical characteristics of the PSCs were measured using a 

balloonbome sensor that measures the optical backscatter at 

two wavelengths from a xenon flash lamp triggered every 7 

seconds. The sonde is especially sensitive to large particles 

that may be present in PSCs. Water vapor, backscatter ratio, 

ozone, and temperature were measured during the balloon 

soundings; their profiles are shown in Figure 5.11. The high 

backscatter ratios shown for the red channel (950 nm) of the 

backscatter sonde below 200 mb (Figure 5.1 lb) are 

associated with tropospheric ice clouds. The water vapor 

mixing ratios in this region (Figure 5.1 la) show saturated or 

even possibly supersaturated conditions. The enhanced 

backscatter in the region 100-25 mb is the signature of PSCs. 

Water vapor mixing ratios in that region are high (6-10 

ppmv) but not saturated. Thus these are not water ice 

crystals but nitric acid trihydrate (HN03 • 3H20) particles 

that form at temperatures above the frostpoint of water. 

Depending on the mixing ratios of water and HN03, the 

nitric acid trihydrate clouds form at temperatures colder than 

45 
30 30 

10 ( a ) 10 , ~) 

... · 25 25 : 20 : 20 

20 20 

3 50 '3 50 

s E s E 

0 = Q) = 

:s cu ~ cu 15 

~ 15 :J) 

~ (/) 100 :ll 100 (/) 

0 < Q) < a: ct 

200 10 200 10 

5 500 

5 

500 

1000 1000 

1 10 100 1000 2.0 3.0 4.0 5.0 6.0 

Water Vapor Mixing Ratio (pprnv) Backscatter Ratio 

Temperature (°C) 

-80 -60 -40 -20 

30 

10 (c) 

25 

20 

20 

'.O 50 s E Cl) ~ 

... 15 J ::J 

II) 

II) 100 Cl) 

... < Q. 

200 10 

" ·. 

.. ·· ... 5 

500 ·· .. 

1000 

0 100 200 

Ozone Partial Pressure (nb) 

Fig. 5. 11. Vertical profiles from Alert, Northwest Territories, Canada, on January 21, 1989, for (a) water vapor volume mixing ratio (solid 

line) and saturation mixing ratio (dotted line); (b) backscatter ratio from the PSC sonde; and (c) ozone partial pressure (solid line) and 

temperature (dotted line). 

46 
about -78'C. As can be seen in Figure 5.llc, temperatures 

reach this low value near the 100-mb level. If temperatures 

drop below water saturation (--80'C at 100 mb and -- 84'C 

at 30 mb), then water ice crystals will form. These larger 

particles will fall out of the stratosphere, removing both 

water vapor and HN03• At the time of these measurements 

no significant dehydration is noted. On January 21 it is 

still dark at Alert (82'N) and over much of the Arctic. 

Since sunlight is required for chlorine that has been 

released by heteorogeneous reactions on PSCs to catalytically destroy ozone, destruction should not yet have begun. 

Figure 5.1 lc shows that this is indeed the case. Ozone 

profiles obtained l ater in February do suggest that ozone 

was destroyed [Evans, 1990). A similar set of measurements is planned for 1990. 

5.2. SPECIAL PROJECTS 

5 .2.1. STRATOSPHERIC OZONE INTERCOMPARISON 

CAMPAIGN 

A NASA-sponsored campaign was conducted at the JPL 

Table Mountain Facility in California July 19 to August 2, 

1989, to intercompare the performance of several kinds of 

instruments measuring stratospheric ozone. Participating 

scientific groups and instruments were NOAA/CMDL and 

NASA/Wallops Island, with ECC ozonesondes; JPL and 

NASAJGSFC, with lidars; and Millitech Corporation, with 

a microwave instrument. Additionally, participants from 

NOAA/CMDL and from AES made total ozone and 

Umkehr observations with Dobson and Brewer spectrophotometers, respectively. Overall, results of the ozone 

measurement comparisons were highly satisfactory 

[Komhyr et al., 1990b]. 

Mean results of 10 sets of comparison measurements are 

shown in Figure 5.12a. "Blind" data are plotted in the 

figure; they were obtained during the campaign prior to 

availability of the data for general examination. Only 2 of 

10 ECC ozonesondes reached an altitude of 39 km; most of 

the rest of the instruments reached altitudes of 34-36 km. 

Figure 5.12b indicates that the ECC ozonesondes, the two 

lidars, and the microwave instrument measured ozone 

amounts between about 20 and 36 km altitude that agreed 

to ±5%. In the region of 36-39 km, ECC ozonesondes 

measured 10% less ozone than did the JPL lidar and the 

microwave instrument, and about 6% less ozone than did 

the NASA/GSFC lidar. 

Seven sets of quasi-simultaneous ozonesonde and 

conventional Umkehr observations were obtained during 

the campaign. Total ozone amounts used in processing the 

raw Umkehr data by the standard inversion method, 

applicable to observations on C wavelengths, were expressed 

47 

\ 

\ 

(a) 

1--~---,,--~--,-~~-.-~~-.-~~-~ 

0 I 2 l ~ 

MEAN OZONE DENSITY 

(b) 

~..i-~~--.~~~-r~~~.----.r---r 

-20 -10 0 10 20 

~ X OZONE DlfffRENCE 

Fig. 5.12. (a) ECC oronesonde (-),IPL lidar (---), GSFC lidar 

-·) and Millitec Corporation microwave(-·) mean ozone number 

densities obtained from I 0 sets of observations at Table Mountain; 

and (b) mean ozone differences in percent: ECC ozonesonde minus 

JPL Jidar (-), minus GSFC lidar (---), and minus Millitec 

Corporation microwave(·-). 
in the Bass and Paur (1985] ozone absorption coefficient 

scale. Averaged data, with the sonde data reduced to 

Umkehr ozone layers, are plotted in Figure 5.13. Because 

the balloon ascents reached varying maximum altitudes, 

there were seven comparisons in Umkehr layers 1 to 5, six 

in layer 6, and two in layer 7. 

Tropospheric differences are large as expected, since the 

Umkehr technique is not very sensitive to ozone in this 

region. The Umkehr method also generally underestimates 

ozone in the region of ozone maximum. In Umkehr layers 

6 and 7, above the ozone maximum, the Umkehr and 

balloon soundings give results that agree to ±5%. 

5.2.2. 0ZONESONDE OBSERVATIONS AT MIRNY, 

A NTARCTICA 

Measurements of the vertical distribution of atmospheric 

ozone were made at Mirny (66.33"S, 93.00'E, elevation 40 m), 

Antarctica, during 1989 to study the ozone decrease 

-..0 

E 

-(]) 

.... 

:J 

(/) 

(/) 

(]) 

.... 

a.. 

. 98 

1.96 

3.9 

7.8 

15.6 

31.2 

62.5 

125 

250 

4.7:1.0 

16.3:1.4 

(+4.5%) 48.4:3.0 

(-3.9%) : 92.3:3.8 

(-9.3%) ~ 126.4:!: 3.1 

.... 

(-4.6%) 109.7:3.8 

(+6.3%) 52.4:4.4 

32.8:t3.2 

38.3:t8.9 

···········SON DES 

-DOBSON 1000 ...__ ........... _ ___. _ ___. __ _. 

0 50 100 150 200 

03 Partial Pressure (nb) 

Fig. 5.13. Averaged data from seven pairs of ECC ozonesonde and 

Dobson instrument Umkehr observations obtained quasisimultaneously during July 23-30, 1989. Indicated ozone partial 

pressures (nb) with standard deviations apply to the Dobson Umkchr 

data. Values in parentheses are mean percent differences in layer 

ozone for the sonde and Dobson instrument Umkehrs. 

48 

indicated in Antarctica in recent years by Dobson 

spectrophotometer and satellite total observations [Komhyr et 

al., 1990c]. The project was a joint U.S.-U.S.S.R. effort 

conducted under the auspices of the US-USSR Bilateral 

Agreement on Environmental Protection--Working Group 

VIII. Most of the observations (20 of 24) were made during 

late winter and spring (August-November). Whereas the 

polar vortex (and, hence, the region of the Antarctic 

springtime ozone depletion) was displaced roughly to the 

west-northwest of South Pole in 1988, i.e., away from 

Mirny, it was situated approximately symmetrically about 

the Pole in 1989. As a result, stratospheric temperatures 

over Mirny during the latter part of August and in September 

1989 were cold enough between 12 and 23 km altitude to 

sustain polar stratospheric clouds and, hence, partial ozone 

destruction by heterogeneous photochemical processes. 

Maximum ozone depletion at Mirny was observed in the 

ECC ozonesonde sounding of October 15 (Figure 5.14). 

Ozone amounts increased substantially above about 70 mb 

over Mirny following mid-October, but reduced ozone 

amounts persisted in the lower stratosphere through 

November . 

5.2.3. 0ZONESONDE OBSERVATIONS AT BRW 

During the early 1989 Airborne Arctic Stratospheric 

Expedition conducted in the eastern Arctic to study 

CD 

:c: 

-60 

TEMPERATURE I 'C J 

- 10 -20 0 20 

20l-H--\~-..+..:~+-~__.::....,._~t-~~-t-~-=--t:.?rt--:---t 

0: 

::l 

(/) 

0: 

a.. 

IQOQt-....L----l~~-1.__;,._~_i_~--''-'-~~-1-~-=--

0 SO 100 ISO 200 2SO 300 

PARTIAL PRESSURE or OZONC INBI 

Fig. 5.14. Ozonesonde (solid line) and air temperature (dashed 

line) data, showing maximum ozone depletion on October 15, 1989. 
possible wintertime stratospheric ozone destruction such as 

1~a1 which occurs in springtime in Antarctica, ECC 

ozonesondes were flown by CMDL personnel at BRW in an 

attempt to detect possible similar ozone destruction in the 

western Arctic. A total of 33 ozone soundings were made, 

spanning the time interval of January 16-April 19. 

No unequivocal evidence appeared in the ozone profiles 

of ozone destruction similar to that which occurs in 

Antarctica in the presence of PSCs. Stratospheric temperatures were never colder than - 70'C and were often as warm 

as -50'C. Thus even nitric acid trihydrate PSCs, which form 

at warmer temperatures (approximately - 78') than do pure 

ice crystal clouds, were not present in the stratosphere over 

BRW. Neither was there evidence in the ozone profiles of 

stratospheric transport of partially depleted ozone from the 

eastern Arctic to the BRW area. 

The BRW ozone profiles could be categorized into two 

basic classes: those that occurred January 25-30, February 

22-March 8, and March 17-24, having characteristics of 

polar air masses with ozone tropopatise press~re· ~llitudes of 

350-450 mb and total ozone of 450-540 DU; and all others 

I -

.... 2 

a: 

·~ 

0 

5 I Tf: BARROM 

1'i OAT(: 22 rrn 09 

1111(: 1027 z ltlS I : CCC 'iA0903 

TlllAL. 03 : 

10 SONOf. 01: 531. 

. ------ ---~-----

ORT(: 21 rce 69 

TIH( : 0119 Z 

I NS l : CCC 5AO'IO I 

50110[ 03: 356. 

. - - - '-----' _I 

so 11111 1')0 200 250 300 

nznur f'nPl 10!. PR[SSIJR[lllfl I 

- 15 

JO 

25 

20 

· IS 

10 

s 

Fig. 5.15. ECC ozonesonde profiles obtained at BRW February 21 

and 22, showing an increase in total ozone of 48% io 1.5 days time. 

The symbols circle, box, and triangle on the ordinate axis of the plot 

denote approximate pressure altitudes of the tropical, mid-latitude, 

and polar tropopause, respectively. 

(except one) having characteristics of mid-latitude air masses 

with ozone tropopause pressure al!itudes of 200-300 mb and 

total ozone of 350-400 DU. One ozone profile, that of 

February 6 with total ozone of 307 DU, exhibited an ozone 

tropopause near 100 mb, characteristic of ozone profiles in 

tropical regions. 

Figure 5.15 is a plot of BRW ozone profiles of February 

21 and 22 obtained 1.5 days apart. Note the large increase in 

ozone (48%) during the interval. The ozone profile of 

February 21 exhibits features of both tropical and 

mid-latitude air masses, whereas that of February 22 typifies 

polar air mass ozone profiles. 

5.3. REFERENCES 

Bass, A.M. , and R.J. Paur, The ultra-violet cross-sections of ozone, 

I, the measurements, in Atmospheric Ozone, Proceedings of the 

Quadrennial Ozone Symposium, Halkidiki, Greece, pp. 

606-1610, D. Reidel, Hingham, MA, 1985. 

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

for Climatic Change, No. 16: Summary Report 1987, I 10 pp., 

NOAA Environmental Research Laboratories, Boulder, CO, 

1988. 

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

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

Environmental Research Laboratories, Boulder, CO, 1989. 

Evans, W.J.F., Ozone depletion in the Arctic vortex at Alert during 

February 1989, Geophys. Res. Lei/., 17, 167-170, 1990. 

Johnson, J.E., R.H. Gammon, J. Larsen, T.S. Bates, S.J. Oltmans, 

and J.C. Farmer, Ozone in the marine boundary layer over the 

Pacific and Indian Oceans: Latitudinal gradients and diurnal 

cycles, J. Geophys. Res .. 95, 11,847-11,856, 1990 . 

Komhyr, W.D., R.D. Grass, and R.K. Leonard, Dobson 

spectrophotometer 83: A standard for total oz.one measurements, 

1962-1987,J. Geophys. Res., 94(D7), 9847-9861, 1989. 

Komhyr, W.D., E.A. Crozer, J.A. Lathrop, and M.A. Winey, ECC 

oz.onesonde observations at South Pole, Antarctica during 1989, 

NOAA Data Report ERL CMDL-5, 247 pp., NOAA Environmental Research Laboratories, Boulder, CO, I 990a . 

49 

Komhyr, W.D., J.A. Lathrop, and D.P. Opperman, ECC ozonesonde 

and Dobson Umkehr observations during STOIC 1989, Digest of 

Topical Meeting on Remote Sensing of the Atmosphere, 1990, 

Vol. 4, pp. 441-444, Optical Society of America, Washington, 

DC, 1990b. 

Komhyr, W.D., J.A. Lathrop, V.N. Arbuzova, V.U. Khattalov, VJ. 

Pilipenko, and V. V. Rudakov, ECC oz.onesonde observations at 

Mimy, Antarctica, during 1989, NOAA Data Report ERL 

CMDL-4, 84 pp., NOAA Environmental Research Laboratories, 

Boulder, CO, 1990c. 

Komhyr, W.D., SJ. Oltmans, R.D. Grass, and R.K. Leonard, 

Possible influence of long-term sea surface temperature 

anomalies in the tropical Pacific on global ozone, Can. J. Phys., 

in press, 1991. 

McPeter.;, R.D., and W.D. Komhyr, Long-term changes in SBUV/ 

TOMS relative to World Primary Standard Dobson 

spectrophotometer 83, J. Geophys. Res., 6J(D2), 2987-2993, 1991. 

Oltmans, SJ., Surface ozone measurements in clean air, J. Geophys. 

Res., 86(C2), 1174-1180, 1981. 

Rosen, J.M., SJ. Oltmans, and W.F. Evans, Balloonbome 

observations of PSCs, frost point, ozone, and nitric acid in the 

North Pole vonex, Geophys. Rts. Lm .. 16, 79 1-794, 1989. 

Watson, R.T., M.J. Prather, and M.J. Kurylo, Present state of 

knowledge of the upper atmosphere 1988: An assessment repon, 

NASA Reference Publication 1208, 200 pp., NASA Office of 

Space Scie. ce and Applications, Washington, DC, 1988. 
6. Acquisition and Data Management 

G. HERBERT (Editor), J. HARRIS, M. BIENULIS, AND J. MCCUTCHEON 

6.1. CONTINUING PROGRAMS 

6.1. 1. STATION CLIMATOLOGY 

The CMDL station climatology is derived from surface 

weather observations of wind direction, wind speed, station 

pressure, air and dewpoint temperature, and precipitation 

amount. The 13-year station climatologies are an important 

record for the interpretation of measured values of aerosols, 

trace gases, and climatic change. The sensors currently in use 

were selected not only for high accuracy but also for ruggedness, to minimize failures in the extreme conditions of the polar 

regions (Table 6.1). Since the last reporting of the complement 

of instrumentation at the stations [Nickerson, 1986], the 

dcwpoint hygrometer has been changed to correspond to the 

hygrometer used by the NWS. To the extent that it is practical, 

WMO siting standards arc followed. 

Barrow 

Descriptions of the BRW station and its climate are given in 

previous GMCC Summary Reports [e.g., DeLuisi, 1981]. Wind 

roses of hourly average resultant wind direction and speed are 

presented in 16 direction classes and 4 speed classes (Figure 

6.1). The distribution of wind by direction for the 1989 wind 

rose shows a higher percentage of winds from the southwest 

quadrant (3 1%) compared with the 12-year climatology (19%). 

The "clean-air sector," the northeast-southeast quadrant, showed 

a decreased percentage of winds (55%) compared with the 

12-year climatology (60%). The anomalous southwest winds 

were primai-ily recorded during the months of January-March. 

The year's peak gust of 43 m s-t on February 25, was the highest 

wind speed ever recorded at the station. 

The average temperature for 1989 (Table 6.2) was 2.4 ' C 

warmer than the climatological average of -12.7 'C. The 

year's minimum temperature of -47'C occurred on January 

26, and the maximum of 21 'C on August l 0, which ties the 

all-time high. January was 7 'C colder than normal, and the 

average pressure for the month was 3 hPa lower than 

normal. On January 30 the pressure reached 1057 hPa, 

matching the old high-pressure record. The high-pressure 

ridge over Alaska persisted into March, advecting Pacific 

maritime air northward and causing unseasonably warm 

temperatures. February 1989 was the warmest February on 

record with a -13 'C average, which is 13 'C above normal. 

Monthly mean temperatures were above normal for 9 

months in 1989. 

Mauna Loa 

In this report the climatology of MLO is regarded as 

consisting of two distinct regimes (Table 6.3) because the 

bimodal distribution of the wind direction changes 

generally consistently with the time of day. The day 

(upslope) period (0600-1800 LST) and the night 

(downslope) period (1800-0600 LST) define the two 

regimes. The 12-year day and night wind roses illustrate 

the two distinct wind patterns (Figure 6.2). 

Day regime. The 12-year day wind rose (Figure 6.2) 

indicates that light wind speeds in the northwest-northeast 

sector were observed nearly 50% of the time. This 

represents the upslope flow attributed to the daytime 

heating of Mauna Loa. The 1989 day wind rose (Figure 

6.3) compares well with the 12-year rose except for strong 

west-southwesterlies representative of storm-related winds 

through the 12-year period. The day wind roses are more 

TABLE 6.1. CMDL Meteorological Sensor Deployment 

BRW MLO SMO SPO 

Sensor Serial Elevation, Serial Elevation, Serial Elevation, Serial Elevation, 

No. m No. m No. m No. m 

Primary anemometer 576 16.7 931 8.5 782 13.7 585 12.2 

Secondary wind Aerovane• 883 38.5 

Pressure transducert 2366 9 225 3397 752 30 8 2841 

Mercurial barometer 641 9 278 3397 961 30 

Air temperature At 8801 2.5 8807 1.7 8807 9 703 2.2 

Air temperature B§ 8802 15.3 8809 37.8 8808 2.3 701 23.2 

Air temperature Ct 8 3.1 46 2.0 2 9.0 835 2.2 

Dewpoint temperature hygrometer* • 8 3.1 46 2.0 I 9.0 3720 2.2 

*Aerovane, Bendix, Inc., model no. 141, Baltimore, MD. 

t Pressure transducer, Rosemount, Inc., model no. 1201Flb, Minneapolis, MN. Heights of all pressure sensors are given with respect Lo MSL 

iLinearized thermistors, Yellow Springs Inst. Co., model no. 44212, Yellow Springs, OH. 

§Thermometer, positioned at the top of the local sampling towerto facilitate an estimation of boundary layer stability. 

••l!ygrothermometer, Technical Services Laboratory model no. 1063, Fort Walton Beach, FL 

50 
BARROW 

1989 

w -.! ___ ; ___ ; 

WINO SPEED (M/ S) 

WS 5 

=5 S WS < 10 

i=::::::J W S ~ I 0 

WIND ROSE 

E 

WINO FREQ 

BARROW 

1977 - 88 

w 

WINO SPEED (M/ S) 

-- 5 ~ lfS < 5 

=5 ~ WS < 10 

i=::::::J W S ~ I 0 

.. i 

.... j 

WIND ROSE 

WIND FREQ 

~ 

E 

Fig. 6.1. Wind roses of surface winds for BRW for 1989 Oeft) and 1977-1988 (right). The distributions of the resultant wind direction and speed are 

in units of percent occurrence for the year and 12-year period, respectively. Wind speed is displayed as a function of direction in three speed classes. 

TABLE 6.2. BRW 1989 Monthly Climate Summary 

Jan. Feb. March April May June July Aug. Sept. Oct. Nov. Dec. 1989 

Prevailing wind w SSW NW ENE E E E E ENE ENE ENE ENE ENE 

direction 

Average wind 5.7 8.6 5.7 6.4 4.9 4.7 5.6 6.1 6.6 7.1 6.1 8.1 6.3 

speed (m s -1) 

Maximum wind 14 33 17 14 13 15 17 16 14 19 17 19 33 

speed* (m s·1) 

Direction of max. 114 232 105 249 80 346 239 272 77 79 72 7 1 232 

wind* (deg.) 

Average station 1011.3 1019.4 1022.8 1017.0 1018.3 1013.8 1009.9 1008.3 1011.9 1011.1 1017.4 1019.7 1015.0 

pressure (hPa) 

Maximum pressure• 1057 1055 1044 1033 1034 1025 1024 1021 1027 1044 1034 1038 1057 

(hPa) 

Minimum pressure• 986 981 1005 998 1002 996 996 999 996 981 1008 1003 981 

(hPa) 

Average air -31.6 -13.0 - 22.4 - 14.4 -8.2 1.3 6.4 7.6 1.7 -7.3 -23.5 - 22.7 -10.3 

temperature ('C) 

Maximum temperature• -3 -2 - 1 2 3 14 18 21 15 3 - 12 - 12 21 

('C) 

Minimum temperature• -47 -36 -40 -29 -24 -4 -1 0 -3 -25 -32 -41 -47 

("C) 

Average dewpoint -35.6 - 14.9 -26.0 - 17.0 -10.! --0.9 6.2 3.8 -3.2 -13.8 -28.3 -25.5 -14.8 

temperature ('C) 

Maximum dewpoint -6 -2 -2 0 2 13 13 8 2 - 18 - 13 13 

temperature• ('C) 

Minimum dewpoint -53 -41 -45 -33 -27 -8 -3 -4 -8 - 30 -36 -45 - 53 

temperature• ('C) 

Precipitation (mm) 0 27 0 2 0 8 61 25 19 0 0 144 

Instrument heights: wind, 16.7 m; pressure, 9 m (MSL); air and dewpoint temperature, 2.5 m. Wind and temperature instruments are on a tower 25 m 

northeast of the main building. 

•Maximum and minimum values are hourly averages. 

51 
i 

, 

MAUNA LOA 

1977-BB 

...... -: .. '·. / 

/ ... , I / l '· .. · ,. 

, 

! 

I ! 

/ 

/ . 

'

! l / 

, . I { I .... ) ..... : ...... , ... ~ ;. i \ i \ i 

; ~ \ 

\ \ \ 

-·-·... ---~~- ··· f-··-·· .... 

--+-·-·····-. .-·-·t-·--·· -~ 

·. \ \ \. ..... .· .... · ..... ! __ .... ....... ,,,. ........... ... ·-.. _L ... -·· .. -

WIND SPEED (M/ S) 

--5,1'5<5 

=5' WS < 10 

c=::JWS ~ 10 

....... I 

-~ ~~---~:~= L~·~:=- ......... .. ... ,..,, 

,·· 

WIND ROSE 

·• ..... 

\,_ \ . 

....... ·\ .. 

\\ "\ \ 

.. \ \. \ •. ' \ \ \ \ \ ~ 

L..J ... 1 \, ..... \ .... \E, -· 

f l I ' J ; f : : : 

i / I I i J . / ... // 

, I 

·· ..... . • ,, • .r 

... -· 

... ·· ~ 

WlllD FREQ 

:r. 

MAUNA LOA 

1977-BB __ ,,...-

.. ·· . .. ·· 

,..,,.--· --------- ..................... 

- --. ·-........ ~-~ 

WIND ROSE 

·~ ... 

/ 

WIND FREQ 

lt 

\ 

Fig. 6.2. Wind roses of the surface winds for MLO for J 9TI-J 988 day (left) and night (right). The distributions of resultant wind direction and speed are 

given in units of percent occurrence for the 12-year period. Wind speed is displayed as a function of direction in three speed classes . 

MAUNA LOA 

1989 

f ./ 

j I I 

/. i 

I 

i ! 

w -I 

\ 

! 

\ 

\ 

.. 

.. ·· 

,E ·x 

/ ,,."' 

/ 

--

...... 

--- ........ --~~: .. :·· ···· .. WIND ROSE 

-· ··-;----..... . .......... ....... .. I ·- _ .. , -···---. ..... 

...... ··· 

MAUNA LOA 

1989 ... 

\ 

\ "· 

.---· 

i-,, ___ __,_·>,.. ,' ···- ··.. '·-... WIND SPEED (M/S) 

--5,WS < 5 ·· ... 

=z!5 ' WS < 10 ·-.. 

WS ~ 10 ·-·~ 

WIND ROSE 

... 

'1ND fREQ 

lt 

Fig. 6.3. Wind roses of the surface winds for MLO for 1989 day (left) and night (right). The distributions 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. Note the scale change in the 

night plOl for 1989. 

52 
Prevailing wind 

direction 

Average wind 

speed (ms ·

1) 

Maximum wind 

speed• (m s·1) 

Direction of max. 

wind• (deg.) 

Average station 

pressure (hPa) 

~aximum pressure• 

(hPa) 

Minimum pressure• 

(hPa) 

Average air 

temperature ('C) 

~aximum temperature• 

("C) 

Minimum temperature• 

("C) 

Average dewpoint 

temperature ("C) 

Precipitation (mm) 

Prevailing wind 

direction 

Average wind 

speed (m s ·

1) 

Ylaximum wind 

speed• (m s·1) 

Direction of max. 

wind• (deg.) 

Average station 

pressure (hPa) 

Maximum pressure• 

(hPa) 

Minimum pressure• 

(hPa) 

Average air 

temperature ('C) 

Maximum temperature• 

('C) 

Minimum temperature• 

('C) 

Average dewpoint 

temperature ("C) 

Precipitation (mm) 

TABLE 6.3. MLO 1989 Monthly Climate Sununary 

Jan. Feb. March April May June July Aug. ScpL OcL Nov. Dec. 1989 

Day 

SE SE SE N NNW NE SE NNE N N NW W N 

5.4 4.5 5.7 3.5 4.0 3.9 5.3 3.8 3.5 3.3 4.2 4.7 4.3 

12 15 14 11 12 12 15 9 9 11 14 12 15 

151 160 129 159 249 164 163 158 156 146 131 283 160 

678.6 678.1 679.4 678.1 680.4 681.4 681.8 681.2 680.2 680.5 680.1 678.9 679.9 

682 682 684 681 683 685 684 683 682 684 685 684 685 

675 674 673 674 676 679 679 679 679 678 677 67 1 671 

4.4 4.8 7.1 5.3 7.4 10.6 10.4 10.8 10.9 8.7 9.1 7.4 8.1 

10 11 15 12 13 18 16 18 18 15 15 15 18 

-4 -3 -1 -1 2 2 3 2 3 -3 -4 

-4.2 -3.5 -4.2 -0.6 -2.0 -4.3 -2.3 -3.2 -4.3 1.5 -9.7 -11.1 -3.9 

47 46 30 115 75 30 70 17 13 23 19 486 

NighJ 

SSE SSE SE SSW SSE SSE SSE SSE SSE S SSE WSW SSE 

5.8 5.1 5.8 3.4 4.1 4.4 5.8 3.6 3.8 2.8 4.2 4.8 4.5 

13 13 20 12 9 12 19 12 11 10 13 11 20 

157 227 230 157 238 166 149 159 159 160 131 279 230 

678.7 678.2 679.3 678.0 680.4 681.2 681.6 681.0 680.1 680.6 680.1 679.0 679.9 

682 682 683 681 683 685 684 683 682 683 684 684 685 

675 673 672 674 676 679 679 679 678 678 677 672 672 

1.2 1.6 3.0 2.2 3.4 6.0 5.8 6.3 6.4 5.3 5.2 3.4 4.2 

6 6 8 7 9 13 12 13 13 9 9 9 13 

- 4 -3 - 1 -1 - 1 2 3 2 -3 -4 

-7.3 -6.6 -6.9 -5.5 -5.7 -9.9 -5.8 -10.6 -12.2 -1.7 -14.6 -14.8 -8.5 

19 27 13 20 8 30 2 0 20 0 12 153 

Instrument heights: wind, 8.5 m; pressure, 3397 m (MSL); air and dewpoint temperature, 2.0 m. Wind and temperature instruments are on a tower 15 m 

southwest of the main building. 

•Maximum and minimum values are hourly averages. 

uniformly distributed than the night wind roses, possibly 

because of the occurrence of variable wind directions during 

the transition periods of dawn and dusk, most of which are 

included in this regime. 

53 

Night regime. The 12-year night wind rose (Figure 6.2) 

shows that 75% of all winds observed were from the 

southwest-southeast downslope wind sector. The 1989 wind 

rose (Figure 6.3) shows a higher percentage of south-
southeasterly winds than does the 12-year rose. These 

anomalous winds are most prevalent in the January-March 

period. Storm-related winds (WS ~ 10 m s·1) are evident in the 

12-year night wind rose, but are considerably reduced in the 

1989 night wind rose. 

The 1989 average day-night temperature difference is 3.9·c, 

and the average dewpoint depression for 1989 is 12.4.C (Table 

6.3). The year's maximum temperature of 18.1•c occurred on 

'June 21 and the minimum of -4°C occurred on January 5. The 

lowest pressure in 1989 of 671 hPa occurred December 12. The 

year's peak gust of 29 m s·I from the southwest was recorded on 

March 2. The precipitation total for 1989 of 639 mm is 120% of 

the normal yearly precipitation. During January-May, 400 mm 

of precipitation was measured, which was 63% of the annual 

amounts. In April the highest precipitation amount of 135 mm 

was measured. August-December recorded only 107 mm 

(17%); November recorded only a trace. The MLO precipitation pattern for 1989 may be correl.ated .with the. La Nina event 

of 1988. 

Samoa 

A comparison of SMO's 1989 wind rose with that for the 

12-year period shows a higher percentage (13%) of northnorthwest winds in 1989 (Figure 6.4). Winds were 

predominantly from the south-southeast sector (53%) in 1989, 

which agrees with the 12-year wind climatology (56%). The 

anomalous northerly winds occurred primarily in January and 

February. The peak gust in 1989 of 29 m s·1 on January 7 set 

a new January record. 

The average temperature for 1989 of 26.6 'C is consistent 

with the 12-year average of 27°C, although January and 

February were a degree colder than normal (Table 6.4). The 

average pressure for 1989 of 1001.5 is 0.5 hPa higher than the 

12-year average of 1001.0 hPa. High pressure values were 

evident during January-March, a time period of anomalously 

northerly winds. 

The precipitation total for 1989 was 2535 mm. This is 375 

mm above the normal yearly amount. Anomalous amounts 

were measured at the beginning of 1989 and in November, 

which measured a record 422 mm. The SMO dry season 

(June-September) was present again in 1989. The most rain 

measured in a 24-h period occurred on December 13 when 149 

mm was reported. The anomalous precipitation, high pressure, 

and northerly winds for the first 3 months of 1989 can be 

correlated with the La Nina event of 1988. Previous periods 

of below-normal sea surface temperatures in the eastern 

tropical Pacific have demonstrated anomalous precipitation 

patterns in many areas of the globe [Arkin, 1989]. 

South Pole 

The distribution of the surface wind direction in 1989 is 

nearly identical to that of the 12-year pattern (Figure 6.5) with 

winds predominantly from the northeast sector (80%). · A 

slightly higher percentage of winds from the east-southeast 

direction can be seen in the 1989 wind rose compared with the 

12-year wind rose. The irregular east-southeast wind 

directions were primarily observed in April. Strong winds 

from the Antarctic plateau were measured during the winter 

period. The strongest of these winds measured 18 m s·I on 

August 24, and set a new August wind speed record. 

The 1989 temperature and pressure averages are consistent 

with the 12-year record, although April, May, and June were 

anomalous (Table 6.5). The average pressure for May of 

668.3 hPa is 10 hPa below the May normal, and temperatures 

averaged 4°C colder than normal during the period. The 

strong winds in August broke the inversion, mixing down 

warm air from aloft, and causing the average surface temperature for August to be 2.5'C warmer than normal. The 

maximum pressure for 1989 of 706 hPa on August 28 was 1 

hPa short of tying the all time high pressure record. 

6.1.2. DATA MANAGEMENT 

During 1989 the performance of the CAMS surpassed that 

of pre'llious years, having an overall downtime of less than 1 %. 

Table 6.6 gives the CAMS operations summary according to 

block type for 1989. The longest downtimes occurred for the 

C02 CAMS at BRW and SPO. These systems were offline 

for 1-2 weeks while the col analyzer and the flow equipment 

were overhauled. 

Every observatory experienced power outages from time to 

time that caused brief losses of data. At MLO the CAMS 

system memory board, a tape controller, and a power supply 

were replaced. Most of the data lost at SMO was due to 

operator error during personnel changeovers, as well as tape 

and tape drive problems. Most notable among the latter was 

the problem of capstans that harl drier!, harclenerl, and cracked, 

leading to errors in writing and reading the tapes. These were 

replaced and the problems disappeared. BRW had a few 

problems related to worn out tapes. 

In an attempt to minimize the effects of two other CAMS 

problems that can cause loss of data, A&DM personnel 

devised a monthly hardware test with the object of locating the 

problems before data are lost. The two problems are clock 

failure when CAMS operations are interrupted, and periodic 

random access memory failure. A clock failure can happen if 

the clock's power circuit is not activated or if the battery is 

worn out; the results are spurious dates and times being 

recorded. The hardware test involves unplugging each box at 

the beginning of each month when data tapes are changed. 

After 1 minute, the operator plugs the box in again, checks the 

clock, and reads the front panel message and the calibration 

constants. If the clock or the memory is not able to recover 

from the deliberate power outage, the problem can be fixed 

during the hardware test and data loss should be reduced. 

During 1989, a CAMS status report was developed that 

provides information on the number of missing blocks 

according to station, box, and tape number, and the overall 

percentage of data acquisition by station for the month. 

Comments are added to the report form to document hardware 

problems, and the form is distributed to the CMDL Director's 

office and the observatories once a month. 

54 
SAMOA 

1989 

' i 

w 

WIND SPEED (M/ S) 

--5,ll'S<5 

=5' WS < 10 

WS l 10 

..... --- ·--·-~r·-·· ·"' - ·--1-···· .... · . ···--r··-· 

,/ ···.-=l~~: 

·,' 

I 

/ . 

··i ··· . ..i .. _, . .f_ ... 

\. \ \ \ 

' ' 

....... 

.. ~·-· 

i 

----i--·· _ __ T1 ·· ······· . 

---~· -- ·· 

·-....... ! 

·-.. --:·.··· ·-·=-rWIND ROSE 

\ \ ··. \ \ 

\ \ \.. \. 

\ \ \ \ \ 

~ \ \ 

.. lJ _LL.L ! ! I I l E 

.! ! : ~ / 

/ / 

_..····· ... ······ 

. I 

I ' ' ' 

I I 

/ ! 

! 

' 

i 

ll'lND rREQ 

"' 

SAMOA 

1977-88 

\ 

\ 

\ 

. . 

' 

\ i 

! 

WIND SPEED (M/ S) 

--5,WS<5 

=5' WS < 10 

•s l 10 

1 -- ~ ••. 

\ 

/ 

WIND ROSE 

\ 

\ 

/ 

I 

\ 

i f I / / 

I 

ll'lHD rREQ 

"' 

Fig. 6.4. Wind roses of the surface wind for SMO for 1989 (left) and 1977-1988 (right). The distributions of the resultant wind direction 

and speed are in units of percent occurrence for the year and 12-year period, respectively. Wind speed is displayed as a function of 

direction in three speed c lasses. 

Prevailing wind 

direction 

Average wind 

speed (ms ·t) 

Maximum wind 

speed• (m s·1) 

Direction of max. 

wind• (deg.) 

Average station 

pressure (hPa) 

Maximum pressure• 

(hPa) 

Minimum pressure• 

(hPa) 

Average air 

temperature ('C) 

'.\1aximum temperature• 

('C) 

:-.iinimum temperature• 

('C) 

Precipitation (mm) 

TABLE 6.4. SMO 1989 Monthly Climate Swnmary 

Jan. Feb. March April May June July Aug. Sept. 

NNW :-/NW SE SE SSE SSE SSE SSE SE 

5.9 5.8 5.0 5.3 4.8 7.7 6.2 5.8 7.9 

17 15 12 12 10 14 13 12 13 

342 92 160 53 124 160 159 156 

999.3 1000.4 1001.4 1000.5 1002.1 1003.6 1003.2 1003.4 1003.5 

1004 1004 1005 1004 1005 1006 1007 1008 1006 

994 997 998 997 999 999 1000 1000 999 

26.6 26.7 27.2 27.3 26.8 26.5 25.8 26.0 26.5 

31 30 31 32 31 29 31 30 29 

22 22 22 23 23 22 23 24 23 

3 12 298 236 250 130 87 171 14 21 

Oct. '.'\ov. Dec. 1989 

SE SE SSE SSE 

5.9 5.2 4.5 5.8 

13 13 12 17 

155 94 141 342 

1001.9 999.6 999.2 1001.5 

1006 1004 1005 1008 

998 996 990 990 

26.7 26.6 26.8 26.6 

31 31 32 32 

23 22 23 22 

249 422 345 2535 

Instrument heights: wind, 13.7 m; pressure, 30 m (MSL); air temperature, 9 m. Wind and temperature instruments are on Lauagae Ridge, 110 m 

northeast of the main building. Pressure sensors are in the main building. 

•Maximum and minimum values are hourly averages. 

55 
··- SOUTH POLE WIND ROSE 

1989 -- : .. -. l}J ... _::: 

. / 

/ ' / 

/ / 

/ -.:, .-··· ·, · 

WS ~ 10 

' --·-··-':""·------

' . ---· ' ,;• .. ·.>···· "· .•. 

', 

\ 

\ 

\ \.. \ 

\. \ \ 

\ \ \ \ 

WIND fREQ 

r. 

Fig. 6.5. Wind roses of the surface wind for SPO for 1989 (left) and 1977-1988 (right). The distributions of the resultant wind direction and speed arc in 

units of percent occurrence for the year and 12-year period, respectively. Wind speed is displayed as a function of direction in three speed classes. 

Prevailing wind 

direction 

Average wind 

speed (ms ·1) 

Maximum wind 

speed• (m s· 1) 

Diree1ion of max. 

wind• (deg.) 

Average station 

pressure (hPa) 

Maximum pressure• 

(hPa) 

Minimum pressure• 

(hPa) 

Average air 

temperature ('C) 

Maximum temperature• 

('C) . 

Minimum temperature• 

('C) 

TABLE 6.S. SPO 1989 Monthly Climate Summary 

Jan. Feb. March April May June July Aug. Sept. Oct. Nov. Dec. 1989 

E ENE NE ESE E E NNE NE NE E N NNE NE 

3.3 4.6 5.8 5.8 5.9 5.7 6.9 7.1 7.3 5.2 5.1 5.7 5.7 

8 10 12 12 14 12 15 17 13 10 10 12 17 

10 321 7 116 35 10 343 308 22 36 18 357 308 

688.0 681.8 682.l 680.2 668.3 671.7 673.9 679.4 676.8 674.5 682.9 689.9 679.l 

694 692 699 703 680 682 689 706 693 689 696 696 706 

681 668 67 4 661 653 663 651 659 653 657 669 681 651 

-28.0 -40.4 -53.6 -(i().5 -62.0 -61.9 -58.5 -56.5 -58.1 -53.1 -37.5 -25.0 -49.6 

-20 -27 -39 -37 -39 -45 -38 -37 -41 -35 -26 -20 -20 

-38 -54 -67 -74 -75 -78 -78 -75 -74 -66 -48 -32 -78 

Instrument heights: wind, 12.2 m; pressure 2841 m (MSL); air temperature, 2.2 m. The anemometer and thermometer arc on a tower 100 m grid 

east-southeast of CAF. Pressure measurements are made inside CAF. 

•Maximum and minimum values are hourly averages. 

56 
TABLE6.6. CMDL CAMS Operations Summary, 1989 

Blocks Recorded and [Blocks Missing] 

Block Expected No. of 

Type Description Blocks 1989* BRW MLO SMO SPO 

A Hourly aerosol data 2190 2164 (26] 217 (19] 2159 [31] 2171 (1 9] 

B Secondary aerosol data Variable 2140 2158 24 1623 

H Daily aerosol data 365 362 [4] 363 [2] 360 [5J 363 (2J 

s Hourly solar radiation data 8760 8659 [103] 8681 (79] 8637 (123] 8686 [74] 

T Daily solar radiation data 365 343 [4Jt 157 [2Jt 184 [OJt 57 [3Jt 

c Hourly C02 data Variable 8006 [170] 8339 [9] 8325 (90] 8183 (169] 

D Daily C02 data 365 356 [4J 363 [OJ 361 [4] 358 [7J 

E Hourly C02 calibration data Variable 410 371 341 393 

F C02 calibration report 52 53 53 48 53 

M Hourly meteorological data 4380 4357 [23] 4362 [20] 4346 [36] 4376 [SJ 

0 Daily surface owne data 365 365 (OJ 364 [IJ 362 (3] 365 [OJ 

w Daily meteorological data 365 365 [OJ 364 [l] 362 [3J 365 [OJ 

I Meteorological calibration 365 363 [2J 364 [l] 362 [3] 365 [OJ 

N Surface owne calibration 52 53 61 62 33 

*Discrepancies between the expected number of blocks and blocks recorded+ blocks missing are due to clock problems or autorestarts. 

tT block added to data suite during 1989. 

6.2. SPECIAL PROJECT: ATMOSPHERIC TRAJECTORIES 

CMDL isobaric trajectory calculations have been 

documented by Harris (1982], and isentropic trajectories 

have been described in Harris and Bodhaine (1983] and 

validated by Herbert et al. [1989]. In addition, most 

Summary Reports contain an article describing the latest 

developments in and studies using atmospheric trajectories. 

Input available for the trajectory calculations consists of 

13 years of gridded meteorological data from NMC. A 

shorter but comparable data set from ECMWF is also 

available for 1980-1989. The latter data set is used in 

comparison studies and for trajectories computed using 

three-dimensions, which were developed this year because 

ECMWF provides vertical wind speeds at each mandatory 

pressure level. The three-dimensional trajectories track the 

winds according to the u, v, and w fields so that an estimate 

of the vertical motion in the atmosphere can be provided 

along with the usual horizontal trajectory estimate. Some 

three-dimensional trajectories were produced for AGASP II 

case studies. They compared favorably with those produced 

by a University of Washington model. 

The following includes most of the organizations for 

which atmospheric trajectories were produced during 1989: 

Institute of Marine Geology, Italy; National Research Center 

for Marine Environmental Forecasts, P.R.C.; University 

College Galway, Ireland; Center for Atmospheric Science, 

Mexico; Institute of Natural Science, Korea; Institute for 

Atmospheric Physics, Yugoslavia; Academy of Atmospheric 

Physics, U.S.S.R.; University of Las Palmas, Spain; 

Atmospheric Environment Service, Canada; Idaho National 

Engineering Loaboratory; Lawrence Berkeley Laboratory; 

NCAR; USGS; University of Colorado; University of 

Alabama; AOML; PMEL; and ARL. CMDL staff responded 

to more than 60 requests for trajectories from within the 

Laboratory as well as from other government agencies, 

universities, and research organizations. Whenever possible, 

trajectories are provided for collaborative studies whose 

theme reflects CMDL's mission. 

A study was completed in 1989 [Harr is and Kahl, 1990] 

that used cluster analysis of trajectories to describe the 

principle flow regimes affecting MLO. Eight years 

(1981-1988) of 10-day MLO back trajectories on the 500-and 

700-hPa surfaces were analyzed. Cluster analysis is a 

multivariate technique that groups cases based on their 

similarity. A method was chosen that minimizes the 

within-group variances, with the result of grouping trajectories that describe similar wind flow patterns. These 

patterns could then each be represented with a cluster mean 

or average trajectory for the cluster, thereby summarizing 

many trajectories with only a few distinct flow patterns. 

The analysis was performed for both levels for each year 

to examine the year-to-year variability. Then trajectories 

were clustered by month to describe the seasonal variations 

in MLO's flow regime. Figure 6.6 shows six cluster means 

for typical years at both levels: (a) 1984, 700 hPa, and (b) 

1983, 500 hPa. Clusters for other years appear in Harris and 

Kahl [1990]. In Figure 6.7, 700-hPa clusters obtained for 

three months, (a) August, (b) October, and (c) December, 

show the transition from the summer easterly tradewind 

regime to the winter flow dominated by westerly winds. 

This trajectory climatology disclosed the following 

features of MLO's flow patterns: 

(1) The gross features of atmospheric transport to MLO 

are similar from year to year. 

57 

(2) Easterly transport occurs 38-54% of the time at 700 

hPa. It is most frequent in summer but is present during all 

months. Easterly winds are not as pronounced at 500 hPa. 

(3) Strong westerly transport from Asia or beyond is 

frequent at both levels. This pattern is strongest at 500 hPa 
50° N 

1983 (b) 

30° N 

10° N 

I 0 ° W 10 ° E 30 ° E 110° E 130° E 150 E 170° E 170° W 150° W 130° W 

Fig. 6.6. Atmospheric transport regimes for MLO, depicted by cluster-mean trajectories at (a) 700 hPa, 1984, and (b) 500 hPa, 1983. Plus signs indicate 

I-day upwind intervals. The nwnbers 10 days upwind of MLO show the percentage of complete trajectories occurring in the cluster (top number) and 

and arbitrary cluster number used for identification (bottom nwnber). 

I 

"', r· • 1 

58 

Fig. 6.7. Atmospheric transport regimes for MLO, by month, depicted 

by cluster-mean back trajectories at 700 hPa for the period 1981-1988: 

(a) August, (b) October, and (c) December. Symbols are as in Figure 

6.6. 
because of the influence of the subtropical jet stream; the 

longest trajectories occur from October through May. 

(4) Both levels exhibit westerly flow patterns that curve 

anticyclonically to approach MLO from the north and northeast. 

This pattern is most pronounced at 700 hPa. 

(5) The flow climatology indicates an annual progression 

from westerly transport during winter to easterly transport 

during summer and a transition corresponding to the migration 

of the North Pacific anticyclone. 

(6) The greatest directional shear between the 500- and 

700-hPa levels occurs during winter and the least during July, 

August, and September. 

6. 3. REFERENCES 

Arkin, P.A., Seasonal Climate Summary, Vol. 2, 737 pp., NOAA/NWS 

Climate Analysis Center, National Meteorological Center, 

Washington, DC, 1989. 

DeLuisi, J.J. (Ed.), Geophysical Monitoring for Climatic Change, No. 9: 

Summary Report 1980, 163 pp., NOAA Environmental Research 

Laboratories, Boulder, CO, 1981. 

Harris, J.M., The GMCC atmospheric trajectory program, NOAA Tech . 

Memo. ERL AR/..,.116, 30 pp .. NOAA Environmental Research 

Laboratories, Boulder, CO, 1982. 

Harris J.M., and B.A., Bodhaine (Eds.), Geophysical Monitoring for 

Climatic Change, No.11: Summary Report 1982, pp. 67-75, NOAA 

Environmental Research Laboratories, Boulder, CO, 1983. 

Harris, J.M.. and J.D. Kahl, A descriptive atmospheric transport 

climatology for the Mauna Loa Observatory using clustered 

trajectories, J. Gtophys. Res .. 95(09), 13651-13667, 1990. 

Herbert, G.A .. J.M. Harris, and B.A. Bodhaine, Atmospheric transport 

during AGASP II: The Alaskan flights (2-10 April 1986), Atmos. 

Environ., 23, 2521-2536, 1989. 

Nickerson, E.C. (Ed.), Geophysical Monitoring for Climatic Change, 

No. 13: Summary Report 1984, 111 pp., NOAA Environmental 

Research Laboratories, Boulder, CO, 1986. 

59 
7. Air Quality Group 

J. BOATMAN (Editor), L. GUNTER, M. LURIA,J. RAY, H. SIEVERING, B. WATKINS, AND C. VAN VALIN 

7.1. CONTINUING PROGRAMS 

7 .1.1. INTRODUCTION 

Research objectives of the AQG are: (1) to improve 

understanding of the acidic deposition phenomenon; (2) to 

determine the amount and fate of various trace species that 

are advected eastward from North America; (3) to provide an 

observational data base to validate the acid deposition 

models; and (4) to gain a better understanding of the 

concentration of acid-causing agents within clouds. 

Emphasis during 1989 was on a new, related activity funded 

by the U.S. Anny Atmosphere Research Group, namely, 

characterization of natural aerosol background in clean 

continental air. The work was conducted aboard the NOAA 

King Air research aircraft (Figure 7.1). Table 7.1 

summarizes the research flights made by the King Air in 

support of our activities during 1989. 

7 .1.2. ATMOSPHERIC LID AR VALIDATION EXPERIMENT 

ALIVE was part of a coordinated multi-institution study 

of aerosol optical properties over a remote continental 

I ~Pfol» • 1 r.,,,,,.,.,. I -----------

1 

TtlC/lnlcian 

(opllona/) 

Fig. 7.1. The NOAA King Air C-90, configured for research. 

TABLE 7.1. NOAA King Air Research Flights 

During 1989 

Date Start, End, 

MST MST 

AUVE-1 

Feb. 7 0823 1018 

Feb. 8 (flight 1) 0745 0938 

Feb. 8 (flight 2) 1520 1705 

Feb. 8 (flight 3) 2107 2255 

Feb.9 1510 1700 

Feb. 10 (flight 1) 0708 0901 

Feb. 10 (flight 2) 1512 1703 

AUVE-2 

July 10 (flight 1) 0817 0946 

July 10 (flight 2) 1330 1518 

July 11 (flight 1) 0703 0900 

July 11 (flight 2) \241 1622 

July 12 (flight 1) 0639 0913 

July 12 (flight 2) 1830 2106 

July 13 1735 2002 

July 14 0237 0502 

AUVE-3 

Dec. 11 0815 1024 

Dec. 11 1503 1725 

Dec. 12 0804 1107 

Dec. 12 1440 1718 

Dec. 13 0804 1035 

Dec. 13 1408 1612 

Dec. 14 0751 1026 

Dec. 14 1524 1724 

Dec. 15 0751 1225 

J. Elki11S Research 

Feb. 24 (flight 1) 0903 1220 

Feb. 24 (flight 2) 1444 1632 

region. Measurements were made of meteorological 

variables, condensation nuclei, and aerosol optical scattering 

and absorption, using the NOAA King Air C-90 research 

aircraft (46RF) equipped with navigational, meteorological, 

and aerosol instrumentation. Flights occurred over 

south-central New Mexico in coordination with groundbased lidar measurements. The present data set allows for a 

calculation of the tropospheric column optical extinction and 

an assessment of the contribution of absorption to this 

extinction. 

A goal of the project was to develop an understanding of 

the effect of hydration on the optical properties of internally 

mixed particles containing both scattering and absorbing 

material. This will allow more accurate predictions of 

in-situ aerosol optical properties, based on known source 

strengths, source emission characteristics, and transport 

pathways to the location in question. 

60 
The discussion here is restricted primarily to the results from 

two typical flights in the 16-flight series: one winter flight 

(February 8, 1989) and one summer flight (July 11, 1989). 

Figure 7.2 shows data from the winter flight, plotted as a 

function of pressure and altitude. Figure 7.2a depicts air and 

dewpoint temperatures; Figure 7.2b shows aerosol backscatter 

from the three-wavelength integrating nephelometer; Figure 

7.2c displays the aerosol black carbon content; and Figure 7.2d 

gives the condensation nucleus concentration. This series of 

flights was the first use of the aethalometer aboard the NOAA 

King Air for absorption measurements, and sampling rate 

problems reduced its sensitivity. Consequently, it was necessary 

to average the black carbon data for the flights of the winter 

series. Figure 7 .2c depicts average black carbon concentrations 

in the boundary layer and in the free troposphere for the three 

flights on February 8 and presents similar data for two flights on 

February 10. 

Figure 7.3 shows data for the same variables, but during the 

summer flight The aethalometer sensitivity was improved by 

this time. Therefore, Figure 7 .3c displays average black carbon 

concentrations, representing aerosol accumulations over periods 

of a few minutes. The horizontal bars in Figure 7.3c depict the 

range of aethalometer readings for each averaging period. 

400 e 400 8 

(a) -T (b) ...... - llO""' .... 

'-, ····· Td 5 

,.. __ 

5 llOO 500 I• 

. ' 

:· 4 4 1 ::t 

:D' llOO ... llOO 

.§.. ~ ~:-; 3~ 3 ! w ; . llC --c-:-t(::: . 700 

~ 700 

:1 - ,\, 2 

If 4' IOO U· 100 " . : I :\ I I 0 900 0 100 --i--i- · 

1000 1000 

o40 .ao .. • 7 .. .. ~ ~ 

Tomp-ure (C) 1.o9 (bani) 

•OO ( ) AUVE·I 400 8 

11 ' :=:~:: (d) s 5 500 . . ; ' •880208 3 500 

0 890210:1 ::; I ? 890210_2 4 4~ 

:D' eoo 

: . ·- ·'. ·'.; <:.: :; llOO 

! 3 3! 

1700 

700 2! Fru Tro I hare HI ht I • ~t'(tl~~ F>~~l """""""" l c 100 

:::::::::::.::<· <:::::;{J : 100 i' 1 

0 100 0 100 ·• 

1000 

40 10 120 0 z z 8110k Cubon (ng/m3) L.og (CH) 

Fig. 7.2. Profiles of (a) air and dewpoint temperatures, (b) aerosol 

backscatter (m·1). (c) aerosol black carbon content, and (cf) condensation 

nucleus concentrations (an·3), from measurements on February 8, 1989. 

The black carbon data include measurements on February 10, 1989. 

The data . in Figures 7 .2 and 7 .3 indicate substantial 

differences between the vertical profiles in winter and 

summer. All flights were limited in altitude by local air 

traffic control, so profiles are available only from ground 

level (1.2 km above mean sea level; 886 mb) to a maximum 

altitude of about 4.5 km AGL (520 mb). 

Data from the wintertime flight show clear evidence of a 

polluted boundary layer extending from the surface to 

approximately 750 mb, overlain by clean air. The 

temperature and dewpoint data show an inversion extending 

from 780 to 760, where the relative humidity is fairly high. 

The optical scattering in the boundary and inversion 

layers is high in winter, (1- 5) x 1Q·S m·1, and the condensation nucleus counts are also high, about 1000 cm·3 • Above 

about 750 mb the aircraft entered a layer of drier air with a 

normal temperature lapse rate. Within this layer the optical 

scattering dimirlished greatly with increasing altitude to 

about 10·

7 m·1 at about 700 mb, and the condensation nucleus 

counts declined by a factor of 10 to about I 00 cm·3 • Above 

700 mb, humidity increased again; dewpoirlt temperatures 

approached air temperatures at 500 mb. Optical scattering 

near 500 mb showed occasional excursions that may 

indicate the presence of hygroscopically grown cloud 

nuclei. The aerosol black carbon data, representing the 

measurement averages, show higher concentrations of 

61 

- T 

.... Td 4 (a) 

3 

2 

0 

so---------~ 

(b) 

70 

800 

90 

..... - -NII-• 

1'110fWl· 1·· 

I • 

1000 1000 -~~"T""~~~~-< 

·20 ·10 0 10 20 30 40 -8 0 

T1mper11tur1 (C) Log [b1c1t] 

500..--------~ 500-..--------~ 

:0 

g 70 

! 

I 800 A. 

900 

(c) 4 (d) 

eoo 

3 

700 

2 

800 

0 900 

1000 1000+--.--.----.---,-"T""-l 

0 100 200 300 400 500 0 2 4 e 

Black Carbon (ng/ m3) Log [CM] (#/cm3) 

Fig. 7.3. Profiles of (a) air and dewpoint temperatures, (b) aerosol 

backscatter (m·1), (c) aerosol black carbon content, and (d) 

condensation nucleus concentrations (cm·3), from measurements on 

July 11, 1989. 
70-150 ng m·3 in the boundary layer, diminishing to 30-50 ng 

m·3 in the cleaner layer aloft. 

In contrast, the summertime data presented in Figure 7.3 

show that the aircraft was at all times within a deep, mixed 

boundary layer of polluted air. The psychrometric plot (Figure 

7.3a) shows a normal temperature lapse rate, and the air being 

dry at all levels. The optical scattering shows large values, 

about 10-s m· 1, and very little vertical structure. Similarly the 

condensation nucleus counts decline by a factor of only 2 from 

ground level to the flight ceiling. In Figures 7.3a, 7.3b, and 

7.3d an inflection is seen at 660-680 mb, suggesting a slight 

change in air mass characteristics at that altitude. The aerosol 

black carbon data show moderately large concentrations at all 

altitudes, with a mean of approximately 100 ng m·

3 but 

slightly lower values at the higher levels. However, none of 

these data show a sharp boundary between a polluted lower 

layer and cleaner air aloft, and so the actual vertical extent of 

the polluted air mass that was sampled is unknown. 

In summary, the wintertime sonndings 'showed a distinct 

boundary layer of polluted air of approximately 1-km depth, 

overlain by clean air. The summertime results showed that the 

aircraft was at all times within a deep, well-mixed layer that 

extended from the surface to above the operational ceiling. In 

both cases, we measured relatively high values of optical 

scattering and absorption, leading to column optical depths of 

around 0.03 for the lowest 5 km segment of the troposphere. 

Absorption typically accounted for 5-10% of the total 

extinction, which was itself of similar magnitude to that 

measured at other remote locations in the southwest United 

States that are impacted by the long-range transport of 

pollutants. It is concluded that the entire region is probably 

suffused with anthropogenic emissions from both nearby and 

distant sources and that distribution and transport are 

dominated by the prevailing meteorology. 

7 .2. SPECIAL PROJECT: SULFUR MONITORING AT MLO 

The longest continuous atmospheric C01 record is from 

measurements performed at MLO [Pales and Keeling, 1965; 

Komhyr et al., 1989, and references therein]. The location of 

the observatory is nearly perfect for global background 

atmospheric measurements because of its remoteness from 

anthropogenic activity, its elevation of 3400 m ASL, and the 

lack of vegetation in the immediate area. But the ongoing 

volcanic activity on the island and its atmospheric release of 

large quantities of C01 and S01 [Casadevall et al., 1987) 

was found to disturb the C01 record under certain 

meteorological conditions [Miller and Chin, 1978). 

The major continuous source of sulfur is the Puu O'o vent 

on the east rift zone of Mauna Loa at an elevation of 500 m 

ASL. Current estimates indicate an emission rate of 

1000-2000 tons S01 day· 1, and an average value of 1200 tons 

day·1 (T. Gerlach, USGS, private communication). The other 

continuous source is the Kilauea crater, which is between 

Puu O'o and the summit of Mauna Loa, at an elevation of 

1000 m ASL. The emission rate from Kilauea is estimated at 

300 tons S01 day·1 [Casadevall et al., 1987). There are also 

smaller sources, but their total contribution is well within the 

estimated uncertainty of the two major ones. In spite of the 

known high S01 emission, there have been no published 

reports on atmospheric S01 concentrations in Hawaii. Gill et 

al. [ 1989) measured particulate sulfur concentrations along 

the west coast of the island and found them to be we11 below 

the U.S. national air quality standards, but 10-20 times 

greater than expected for a remote marine area. 

Little information is available on global background 

concentrations of S01 in the marine boundary layer (BL) and 

the free troposphere (FT) at MLO. Maroulis et al. [1 980) 

reported average S01 concentrations, based on aircraft 

measurements, of 0.089 ± 0.069 and 0.122 ± 0.085 ppbv for 

the BL and FT, respectively, in the Northern Hemisphere, 

and 0.057 ± O.Ql 8 and 0.09 ± 0.021 ppbv for the BL and FT 

in the Southern Hemisphere. Herrmann and Jaeschke (1984) 

reported an average S01 concentration of 209 ng m·3 

(approximately 0.08 ppbv) over the Atlantic Ocean at 

various sites. Berresheim (1987) measured average 

concentrations as low as 0.011 ppbv over the sub-Antarctic 

and Antarctic ocean area. In a series of studies near 

Bermuda [Luria.et al., 1987, 1989), S01 concentrations were 

below the detection limit of 0.1 ppbv, with a few brief 

exceptions. In a more recent study near Bermuda [Luria et 

al., 1990), using a more sensitive technique, 0.06 ± 0.035 

and 0.065 ± 0.04 ppbv were reported as average 

concentrations for the BL and FT respectively. In the latter 

study, comparable values of 0.050 ± 0.040 pptv for both the 

BL and FT were observed using the filter pack technique 

[Boatman et al., 1990). 

AQG began a sulfur monitoring project at MLO in 1988. 

The study was set up to test the following hypotheses: 

(1) Atmospheric sulfur is a surrogate for volcanic 

contamination at MLO. 

(2) The background atmospheric sulfur concentration in 

the FT 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 S01 gas monitor 

was installed in November 1988. The CSI device measures 

all sulfur gases, has a detection limit of 1 ppbv for 1-min 

samples, and has a response time of 10 seconds. The TECO 

device measures only S01, has a detection limit of 0.1 ppbv 

for 1-min samples, and a response time of 1 minute. The 

two instruments are described by Boatman et al. (1988). 

Data obtained in 1989 indicate that most of the time, S01 

concentrations at MLO are as low as those observed in other 

remote locations. Occasionaily, high nighttime S01 events 

were observed. Because they occurred in association with 

abnormally high C01 concentrations, the source is believed 

to be volcanic, with emissions near the MLO summit. 

Highest S01 levels, up to 1000 times background levels, 

were observed at times concurrent with daytime upslope 

winds having a predominant wind direction of northerly to 

northeasterly. Major sources of the S01 were most likely the 

Puu O'o vent on the east rift zone of Mauna Loa, and the 

Kilauea crater. An annual cycle (high wintertime, low 

summertime values) in S01 was also observed and is 

tentatively attributed in part to the seasonal variations in sol 

to so;· conversion rate. 

62 
7.3. REFERENCES 

Berresheim, H., Biogenic sulfur emission from the sub-Antarctic 

and Antarctic oceans, J. Geophys. Ru .. 92, 13245-13262, 

1987. 

Boatman, J.F., M. Luria, C.C. Van Valin, and D.L. Wellman, 

Continuous atmospheric measurements aboard an aircraft: A 

comparison between the flame photometric and the pulsed 

fluorescence methods, Atmos. Environ., 22, 1949-1956, 1988. 

Boatman, J.F., W.C. Keene, M. Luria, J.D. Ray, C.A. Barwell, K. 

Gorzelska, M. Fennel, D.R. Hastie, A.A.P. Pszenny, and D. 

Whelpdale, An intercomparison of the chemical and 

meteorological data generated from aircraft and shipboard 

sampling during GCE/CASE/W A TOX, NOAA Tech. Memo. 

ERL ARL-186, 26 pp., NOAA Air Resources Laboratory, 

Silver Spring, MD, 1990. 

Casadevall, T.J., J.B. Stokes, L.P. Greenland, L.L. Malinconico, 

J.R. Casadevall, and B.T. Furukawa, S01 and C01 emission 

rates at Kilauea Volcano, 1979-1984, in Volcanism in Hawaii, 

edited by R.W Decker and T.L. Wright, U.S. Geological 

Survey Professional Paper 1350, pp. 771-780, USGS, 

Washington, DC, 1987. 

Gill, T.E., T.H. Tanda, T.A. Cahill, D. Taylor, and H. Matsuura, 

Air quality on Hawaii Island during a Kilauea eruption, paper 

presented at the 82nd Annual Meeting of the Air and Waste 

Management Association, Anaheim, CA, June 1989. 

63 

Herrmann, J., and W. Jaescke, Measurements of H1S and S01 over 

the Atlantic Ocean, J. Atmcs. Chem., 1, 111 -123, 1984. 

Komhyr, W.D., T.B. Harris, L.S. Waterman, J.F.S. Chin, and K.W. 

Thoning, Atmospheric carbon dioxide at Mauna Loa Observatory: 

NOAA/GMCC measurements with a nondispenive infrared 

analyzer, 1974-1985,J. Geophys. Ru., 94, 11429-11436, 1989. 

Luria, M., C.C. Van Valin, J.F. Boatman, D.L. Wellman, and R.F. 

Pueschel, Sulfur dioxide flux measurements over the western 

Atlantic Ocean. Atmcs. Environ., 21, 1631 -1636, 1987. 

Luria, M., C.C. Van Valin, J.N. Galloway, W.C. Keen, D.L. Wellman, 

H. Sievering, and J.F. Boatman, The relationship between 

dimethylaulfide and particulate sulfate in the mid-Atlantic Ocean 

atmosphere, Atmcs. Environ., 23, 139-147, 1989. 

Luria, M., C.C. Van Valin, R.L. Gunter, W.C. Keene, D.L. Wellman, 

J.N. Galloway, H. Sievering, and J.F. Boatman, Measurements of 

low concentration of sulfur dioxide over the western Atlantic 

Ocean during CASE/WA TOX, Global Biogeochem. Cycles, 

submitted, 1990. 

Maroulis, P.J., A.L. Torres, A.B. Goldberg, and A.R. Bandy, 

Atmospheric S02 measurements on project GAMTAG, J. 

Gtophys. Res., 85, 7545-7549, 1980. 

Miller, J.M., and J.F.S. Oiin, Shon term disturbances in the carbon 

dioxide recorded at Mauna Loa Observatory, Geophys. Res. Lett., 

5, 669-671, 1978. 

Pales, J.C., and C.D. Keeling, The concentration of carbon dioxide in 

Hawaii, J. Geophys. Ru., 70, 6053-6076, 1965. 
8. Nitrous Oxide and Halocarbons Group 

T.M. THOMPSON (Editor), J.W. ELKINS, J.H. BUTLER, B.D. HALL, K.B. EGAN, C.M. BRUNSON, 

J. SCZECHOWSIG, AND T.H. SWANSON 

8.1. CONTINUING PROGRAMS 

8.1.1. FLASKSAMPLES 

The flask air-sampling program continued at BRW, NWR, 

MLO, SMO, SPO, and ALT as usual throughout the year, 

with only two minor changes. Larger 1-L flask pairs were 

pressurized monthly beginning in March at BRW, NWR, 

MLO, and SMO to meet the larger sample requirements of 

the LEAPS project. In November, personnel at SPO began 

using a higher pressure pump (3 atm) to fill flask pairs 

during their summer s~pling period. All CMDL stations 

will convert to this higher pressure pump in early 1990 to 

provide sufficient sample amounts for both the LEAPS and 

flask projects. 

The automated flask analysis system was completed 

according to the original design. However, extensive tests 

showed some problem areas and the need for redesign. The 

redesign was completed, and implementation and tests will 

continue into 1990. 

Two calibration gas tanks, T3088 and 62631, were 

intercompared with standards maintained by the OGIST in 

Beaverton, Oregon. This work was done in late April. 

Preliminary monthly mean N20, CFC-11, and CFC-12 

concentrations measured at BRW, NWR, MLO, SMO, and 

SPO during 1989 are listed in Table 8.1. Figure 8.1 shows 

monthly mean N20 data for these stations for 1977-1989. 

The annual N20 increase is approximately 0.2% at all the 

sites. BRW data exhibit a weak annual cycle. This cycle is 

more apparent in the continuous GC record. 

CFC-12 and CFC-11 monthly mean concentrations a.re 

plotted in Figures 8.2 and 8.3. For the 1977-1984 period, the 

annual increase for each is less than it is for the 1985-1989 

period. It appears that the source strength of these two 

halocarbons is increasing. The ratio of CFC-12 to CFC-11 

concentrations has shown no significant change during the 

13-year period, and therefore usage of the two gases is 

increasing proportionately. 

N20, CFC-11 , and CFC-12 data for ALT continued to be 

erratic; results from flask pairs did not match well. Actual 

flask pair averages are shown in Figure 8.4. BRW and ALT 

data compare favorably on average. 

8.1.2. RITS CONTINUOUS GAS CHROMATOGRAPH 

SYSTEMS AT CMDL BASELINE STATIONS 

In-situ sampling of air continued at BRW, MLO, and 

SMO. Eight analyses were made each day for N20, CFC-12, 

CFC-11, CFC-113, methyl chloroform (1, 1, 1-trichloroethane), and carbon tetrachloride. At SPO, these gases were 

sampled and analyzed 12 times per day [Elkins et al., 1988]. 

In January 1989 processing of the chromatographic data 

began for both peak area and peak height. Concentrations 

based on peak height a.re sometimes more precise, yielding 

less scatter in the data. Small peaks such as those of methyl 

chloroform and carbon tetrachloride are prone to precision 

problems, especially if other substances are not 

chromatographically resolved from them. Processing 

programs were written to retrieve pre-1989 chromatograms 

and determine peak heights. A SMO peak-height data base 

TABLE 8.1. Monthly Mean Concentrations in 1989 of N20 (ppb by mole fraction in dry air), CFC-12 (ppt), and 

CFC-11 (ppt) From Air Samples Collected in Flask Pairs at BRW, NWR, MLO, SMO, and SPO 

N20 CFC-12 CFC-II 

1989 BRW NWR MLO SMO SPO BRW NWR MLO SMO SPO BRW NWR MLO SMO SPO 

Jan. 308.5 308.8 308.1 305.9 307.1 459.5 453.6 453.7 437.4 427.4 274.6 269.6 266.6 260.4 

Feb. 309.7 311.5 309.1 309.0 460.0 455.8 447.4 440.5 276.7 270.9 264.3 257.1 

March 307.8 308.4 308.6 307.9 460.8 447.0 450.9 435.0 278.3 267.7 265.6 258.9 

April 309.2 309.4 309.7 306.5 461.6 455.3 454.I 437.8 278.5 270.8 269.6 258.4 

May 309.4 310.6 308.8 306.5 463.1 459.I 452.8 440.6 276.6 271.1 268.8 258.7 

June 308.7 311.6 309.4 308.5 459.8 461.4 461.9 432.2 275.6 272.4 270.2 254.2 

July 310.9 309.8 308.4 306.6 468. I 475.4 453.8 443.1 279.1 285.7 268.4 258.9 

Aug. 309.3 311.5 309.3 309.2 464.1 468.3 458.4 442.3 274.9 277.1 271.3 263.3 

Sept. 309.0 310.0 309.7 308.2 467.1 467.5 460.6 445.2 277.6 279.6 273.7 262.I 

Oct. 308.4 310.6 309.7 306.9 471.0 464.2 464.1 448.4 283.5 275.9 273.8 263.S 

Nov. 310.4 309.6 308.4 307.8 477.1 470.8 467.2 448.I 290.0 280.7 272.2 263.8 

Dec. 309.4 309.4 309.S 308.0 308.2 478.1 468.1 459.7 4Sl.6 445.7 288.2 276.7 276.3 266.2 259.8 

These data are provisional, pending final calibration. 

64 
320 

310 

-300 .c 

Q. 290 

.s 310 

I: 300 

0 

+:: 290 

ca 

.... 310 ... 

I: 300 Q) 

(,) 290 

I: 

0 310 

0 300 

ON290 

z 310 

300 

290 

-

-

. 

-

. 

-

-

-

-

BRW . . ·- ··• ~ 

'¥.- -.. .. - - Slope= 0.60 +- 0.04 ppb yr-1 

NWR . . ·~ .. .... .. ,. . .. . - - Slope" 0.63 +- 0.05 ppb yr·1 

MLO -- - . . ·- . ... , ... . -- . ........... .... - Slope ,. 0.66 +- 0.04 ppb yr-1 

SMO ... - . ·.. . ; - - .. - , ... ,-·. ., Slope .. 0.72 +- 0.05 ppb yr-1 

SPO - .. .. .. ' ....... - Slope = o.58 .... o.o9 ppb yr-1 

11 78 79 00 01 02 83 84 es 0e 01 88 89 

Time (year) 

Fig. 8.1. Monthly mean concentrations of N20 (C02 and H20 

corrected) from the CMDL flask air sample network. The trends 

and 95% confidence intervals are also shown. 

was created using these programs. Other station peak-height 

data will be similarly obtained in 1990. 

In April the BRW system was modified so that all three 

columns could be backflushed. MLO and SMO systems 

were previously modified in 1988. Precision has been 

improved because of this change. 

Time (year) 

Fig. 8.2. Monthly mean dry concentrations of CFC-12 from the 

CMDL flask air sample network. The trends and 95% confidence 

intervals arc also shown. 

300 

250 BRW 

~200 

C.150 

.S100 

I: 250 NWR 

0 200 

... 150 ca 

.... 100 ... MLO I: 250 

Q) 200 (,) 150 I: 

0 100 

0 250 SMO 

,... 200 ,... I 150 

0 

u. 

100 

250 SPO 

0 200 

150 Slope= 9.30 .... 0.63 p yr-1 100 n 78 79 80 81 82 83 84 es 88 87 88 89 

Time (year) 

Fig. 8.3. Monthly mean dry concentrations of CFC-I I from the 

CMDL flask air sample network. The trends and 95% confidence 

intervals arc also shown. 

65 

N . . . ........ .. 490 

'7 460 

u . . .. ··~ ········· .. '-········· .. .. ............ , ..... .,,,. u. 

u 

b - 430 - • 

310-4-~~~~~~~~~-+-~~~~~~~~~~ 

~ ~ -"' ~ 280 - ..................... ............ .... .................. . . ... -

u. 250 - -

u 220 c 

1988 1989 

Fig. 8.4. Flask sample concentrations for (a) N20, (b) CFC-12, and 

(c) CFC-I I at Alert observatory, Canada. The dashed lines are 

spline fits to corresponding BRW flask sample data, for comparison. 

In June a new operations manager was hired to oversee 

the operation of the equipment at the field sites, provide 

support when equipment or software failures occur, and 

supply expendables like carrier gas, paper, and disks. 

Version 4.2 of the software was completed and tested. 

This revision changes the way gas is sampled at the field 

sites. Previously the order of analyses was (1) calibration 

gas 1, (2) calibration gas 2, and (3) outside air. Now the 

order is (1) calibration gas 1, (2) outside air sample 1, (3) 

calibration gas 2, and (4) outside air sample 2. This 

increases the number of times air is sampled from once every 
3 hours to once every 2 hours for hourly analyses. Another 

change incorporated in the software is storing data using two 

floppy disk drives instead of a single floppy drive and an 

emulated disk in RAM. 

Both software changes also required hardware changes. 

In October, an eight-port stream selection valve replaced the 

old six-port valve at BRW. A dual high-density (1.5 Mbyte) 

floppy drive was installed. These same hardware and 

software changes will be made at the other sites in early 

1990. 

A new RITS GC system, incorporating the new software 

and hardware, was set up and tested in Boulder. This 

equipment will be moved to NWR in early 1990 to complete 

the in-situ measurement program. All flask sites except ALT 

will then have GC's. 

Because of increased data processing needs, an HP340 

workstation was purchased with a 330-Mbyte hard disk. 

This is the first acquisition toward the move to a group 

computer network. 

The 2.5-year record of daily average N20 concentrations 

from the in-situ GC's at BRW, MLO, and SMO is shown in 

Figure 8.5. The annual cycle at BRW has a February 

maximum and an August-September minimum similar to the 

periods of the maximum and minimum observed in C02 

concentrations at BRW. Data for SMO in 1988 appear to be 

cyclic, but the cycle is not repeated. Because N20 has a 

s easonal cycle and is growing at a small rate, it is difficult to 

establish an annual growth rate with only 2 years of data. 

The calculated growth rate of atmospheric N20 concentration 

for 1988-1989 at BRW is about 0.6 ppb yr1. However, the 

MLO record for N20 shows li1tle growth because of the short 

record period and larger experimental error in the 1987 data. 

t 312_,...,.......:,....,.......,....,....... ............................................................................................ ~ 

-308 

.c 

Cl. 

Q.304 

- BRW g 312~_._ ............... 4-+...--+-+-+--+-+ __ -+-......_++-+-+-HH-+-++-i 

;: 

t! 308 

-

c 

Cl) 304 

u 

c 

:··. 

MLO 

0 312~-+-+-+-+-+-+-........ -+-+-+-<1-+-+++-4-+-+-+-++-+-1-+--+-i--Ht--1 

0 

0 308 I'll 

z 

SMO 

300 JJASONDJFMAMJJASO~OJFMAMJJASONO 

1987 1988 1989 

Fig. 8.5. N20 daily mean concenlralions at BRW, MLO, and SMO 

obtained from the in-situ RITS GC's. The trends were generated 

using least squares regression analysis. 

The growth rate at SMO during 1988-1989 is about 1 ppb 

yr 1• This value is higher than at other stations and may be 

the result of calibration gas problems associated with 

calibration gas tartk changes in 1988. 

66 

Daily mean CFC-12 concentrations derived from the gas 

chromatograph measurements are shown in Figure 8.6. The 

annual increase is about 19 ppt yr·1 during 1988-1989 for all 

three stations. This result confirms observations from flask 

data during the past few years. 

Carbon tetrachloride concentration at our sampling sites 

appears to have been steady during the past 2 years, in the 

range of 100-110 ppt. As an example, SMO data are shown 

in Figure 8.7. 

550_,.....,.....,........,...,.....,....,.....,....,,....,......,....,. ....... ,.....,....,.........,..........,.. .............................................. .., 

-Q. 500 

Q. 

-450 

c: 

0 BRW 

+: 5504-+-+-+-+-+-+-t-+-+-1~+-+-+-+-+-+-t-+-+-~-+-I~+-+-+-+-+~ 

ca 

I.. 

c 500 

Cl) 

u c: 450 

0 MLO 

0550+-+......,-+-+-+-++-+-+-+-+......,-+-+-+-+-+-++-+-+-+-+-+-+-+-+-H 

C\I 

,... u 500 

u.. 

(.) 450 

SMO 

4oo JJASONDJFMAMJJASONDJFMAMJJASOND 

1987 1988 1989 

Fig. 8.6. CFC-12 daily mean concentrations at BRW, MLO, and 

SMO obtained from the in-situ RITS GC's. 

115 

':t::" 

Q. 110 

Q. 

-105 ~ 

-

0 100 

0 

95 

SMO 

90-l--+---+~+--+--+--+---+~+---+--+--+--1 

1989 

Fig. 8.7. SMO CCl4 concentrations from the in-situ RITS GC. The 

air was sampled every 3 hours. 
Quantization of methyl chloroform still remains a problem 

because of an unknown contaminant in some of our 

calibration gases. 

8.1.3. Low ELECTRON ATIACHMENTPOTENTIAL 

SPECIES 

Although formal flask sampling for LEAPS gases began 

in March, a number of changes were made throughout the 

year in the sampling and analysis of LEAPS gases. By 

November, one of the main problems limiting these 

measurements was resolved when the old flask pump at SPO 

was replaced with a new sampling pump capable of filling 

flasks to a gauge pressure of 3 atm. The same type of pump 

will be installed at the other CMDL stations early in 1990. 

Contamination tests have shown the pumps to be clean and 

not a source of CFC-113, a commonly used cleaning agent. 

Analytical columns were changed as the GC was optimized 

for the various measurements. Initially, gases were 

separated with a 0.53 mm x 50 m methyl-silicone column, 

which was changed in August to a 0.53 mmx 25 m Poraplot 

Q column, and was ultimately replaced by a 0.32 mmx 10 m 

Poraplot Q column. The Chrompack cryotrap was modified 

extensively to allow for the direct measurement of samples 

from flasks and to improve overall sensitivity of the 

measurements. 

Insufficient data are available to calculate atmospheric 

trends of the LEAPS gases from flask air samples collected 

at the CMDL stations. However, flask samples collected 

from over the Pacific Ocean during the RITS-89 cruise 

(January-April) on the NOAA ship Discoverer were analyzed 

for H-1301, H-1211, and CFC-113, as were five 8-L flask air 

samples remaining from the SAGA II cruise (May-July 

1987) in the West Pacific and East Indian Oceans. Growth 

rates for these gases (Table 8.2) were estimated both by 

considering the differences between 1987 and 1989 

measurements and by evaluating the latitudinal gradients 

(Figure 8.8). These estimates are only preliminary; they are 

based on small data sets, representing only two "snapshots" 

in time. Also, the northern hemispheric CFC-113 values 

from the 1989 cruise were affected by urban contamination 

TABLE 8.2. Estimated Annual Growth Rates for LEAPS 

Gases, Calculated from RITS-89 and SAGA II (1987) Data 

Gas 

H-1301 

H-1211 

CFC- 113 

Method 1 

25.7% 

4.4% 

10.1% 

Method 2 

23.6% 

10.8% 

Data are shown in Figure 8.8. Method 1 involves direct 

calculations of the average difference between samples collected 

between 30'S and 40'N on both cruises. Method 2 involves 

calculations based on the measured latitudinal gradient, a relative 

production of 20:1 for the two hemispheres, and an assumed 

interhemispheric exchange time of 1 year [see Butler ti al., 1989). 

67 

3 

2.5 H-1301 

1.5 

2 

~ 1·'-..... -~ -... a 0.5 Q. 

Q. 

-

0 2 .5 H-1211 

:; 2 

a: 1.5 .... .... ~.l- en 

c • 

:8 0.5 b 

:E 

>o CF::JJ ... 70 c 

eo 

50 

40 

~ c 

30-70 ~ 0 35 70 

Latitude 

Fig. 8.8. Dry mixing ratios versus latitude in degrees for (a) 

H-1301, (b) H-1211, and (c) CFC-113, measured in flask air 

samples collected during SAGA Il in 1987 (triangles) and the RITS 

cruise of 1989 (circles), and in air from a cylinder filled at NWR in 

1988 (stars). Estimated growth rates are given in Table 8.2. 

as the ship proceeded along the California coast during a 

period of strong offshore winds. The growth rates for 

H-1301 calculated by either method agreed well, but there is 

a discrepancy in results for H-1211. This discrepancy should 

be resolved when more data from our stations become 

available. 

Sample concentrations of the LEAPS gases to date have 

been determined by response ratio to CFC-12 compared 

with the same ratio for a cylinder of NWR air (Scott 

cylinder SRL-K-009288, Aculife-5-treated steel, filled 

November 1988 at NWR). However, a detailed evaluation of 

the response curves for gravimetrically prepared standards 

shows that the response of the halons, and to a lesser extent 

CFC-113 and CFC-12, is nonlinear (Figure 8.9). 

Consequently, the LEAPS GC will be modified further in 

1990 to allow measurement of exact sample volume so that 

nonlinearities in the response can be evaluated. This will 

lead not only to more accurate results but also much better 

precision. 

8.1.4. GRAVIMETRIC STANDARDS 

A principal goal for 1989 was the development of 

independent calibration scales for all RITS gases. CFC-113, 
1.1 1.4 -.. 1-.. .. .... .... .... a .... ............ .... b 1 ,_ .... .... - 1.2 - . .. - .... .. .. .... .... .. .. - .... .. .. .... G> ...... .... en 0.9 ,_ "It ... - 1 - ..~ c - H-1301 ..... ...... 0 H-1211 .... Q. .... en 

G> 0.8 0.8 '"--·· 

a: 0 1 2 3 0 0.5 1 1.5 2 u 

c 1.1 1.2 0 

(.) 

- c d ... t-·······e- 1.1 

0 1 ......... -. .. .......... ._ . u • ·-···· 

ca 1 

u. ........... G> 0.9 ,_ - en ........... ~---····· ~ CFC-113 0.9 c CFC-22 0 

Q. 

en 0.8 0.8 

G> 0 1 2 3 4 0 1 2 3 4 5 8 a: 1.2 Normalized Response "C 

G> 

~ .. ~---··· e 

ca .... 1.1 .. - E -- --

_ .. ... .. .. 0 

z 1 •• 

CFC-12 

0.9 

0 5 10 15 20 

Normalized Response 

Fig. 8.9. Response curves for (a) H-1301, (b) H-1211, (c), CFC- 113, (d') CFC-22, and (e) CFC- 12. The data show that nonlinearities in the 

detector response should be considered in measuring these gas concentrations. (Although CFC- 12 is not a LEAPS gas, it is used to estimate 

sample volume for the LEAPS measurements.) A horizontal plot for the response factor is indicative of a true linear response of the detector 

to the compound being analyzed. 

CH3CC13, and CC14 have proved to be the most difficult to 

quantify. Several measures were taken to improve our 

ability to prepare accurate standards at the part per trillion 

level. Aluminum tranfer tubes were Aculife-treated to 

minimize adsorption and surface reactions during the 

transfer step for CH3CC13 and CC14• Specially cleaned 

valves containing as little CFC-113 as possible were 

purchased and tested. 

The gravimetric standards prepared in 1989 are shown in 

Table 8.3. The CFC-113 standards were prepared in both 

Aculife-treated aluminum cylinders and 33-L stainless steel 

cans to investigate possible valve contamination, and a 

calibration curve (Figure 8.10) was prepared. No valve 

bias was observed within experimental error. CMDL 

participated in an intercomparison in which flask air was 

analyzed for CFC-113. Our result was 36% higher than 

68 

that of OGIST (fable 8.4). 

Another goal for 1989 was to replace calibration 

standards at the CMDL observatories and to obtain 

standards for use during cruises and in the laboratory. This 

was accomplished by filling several Aculife-treated 

aluminum tanks and 33-L stainless steel cans with NWR 

air. These working standards were carefully calibrated 

using our gravimetric standards. Two each of the new 

working standards were installed at BRW, MLO, and SMO 

observatories. These new standards should eliminate 

CFC-113 contamination problems and help resolve minor 

discrepancies in results obtained among stations. 

Standards support for various other projects continued as 

in the past. As indicated in Table 8.3, standards were 

prepared for the LEAPS project, special RITS projects, and 

the CMDL Carbon Cycle Group. 
TABLE 8.3. CMDL Gravimetric Standards Prepared in 1989 

Set Compounds in Cylinder No. of Cylinders Range Project 

CFC-I I, CFC-113, CH3CCl3, CC14 2 

2 N10 2 

3 N10, C02 4 

4 N10,C02 7 

5 CFC-113, CFC-I I 6 

6 H-1301 2 

7 H-1211 I 

8 CFC-22 2 

9 co 8 

2 

,, 

-

G> CFC-113 N .A 1.5 s.d. 2 ppt ca " 

E 

... Jt,,:' 0 1 ,• 

c 

- Jt,,:' 

G> " fl) 

c 0.5 ... 0 ,. 

Q. 

fl) 

G> ~ 

a: 0 

0 25 50 75 100 125 

Concentration (ppt) 

Fig. 8.10. The normalized calibration curve for CFC-113. It is 

linear in the 10-1 20 ppt range and has a residual standard deviation 

of about 2 ppt. 

TAB LE 8 .4. Comparison of Concentration Scales for 

CFC-1 13 from CMDL and OGIST 

NOAA 

OGIST 

CFC-113, 

ppt 

69.9 

51.0 

Standard Deviation, 

ppt 

1.9 

0.6 

8.2. SPECIAL PROJECTS 

8.2. l. RITS DISCOVERER CRUISE 

Atmospheric and surface water N10, CFC-11, CFC-113, 

methyl chloroform, and CC14 were measured aboard the 

ppb, ppt NOAA/RITS 

ppb NOAA/RITS 

ppb NOAA/RITS 

ppm NOAA/RITS 

ppb, ppt NOAA/RITS 

ppm, ppb NOAA/LEAPS 

ppt NOAA/LEAPS 

ppm, ppb NOAA/LEAPS 

ppm, ppb NOAA/CC 

NOAA research ship Discoverer on the RITS-89 cruise from 

February to April 1989. Dissolved N20 at depth was also 

measured. The cruise track extended south from 47'N to 

60'S along l lO' W and then returned northward along 140' W 

(Figure 8.11). The purpose of the cruise was (1) to measure 

the interhemispheric gradient of these trace gases in the 

atmosphere, (2) to quantify the ocean's effect on these trace 

gases in the surface waters, (3) to measure the biological rate 

for production of dissolved N10, and (4) to compare these 

measurements to those from CMDL observatories. Surface 

waters near the equator were found to have N20 supersaturations as high as 140%. Resulls from this cruise indicate that 

previous estimates for the global production of N10 may 

have underestimated the strength of the ocean source, which 

could be as high as 30% of the total natural source. 

8.2.2. Fr-IR SPECTROMETER ARCHIVE PROJECT 

Working in collaboration with scientists at NOAO/NSO, 

CMDL scientists from the CC and NOAH Groups restarted 

FT-IR spectrometric observations in January 1989 at Kitt 

Peak, Arizona (30'N, 112'W), which had been terminated in 

1985. The purpose of resuming the observations was to 

compare trace gas concentrations derived from the FT-IR 

spectrometer observations with values determined from flask 

air samples collected at the nearest CMDL site , NWR (40'N, 

105'W). The sun is tracked at Kitt Peak by a solar telescope, 

and its beam is directed into an FT-IR spectrometer. Trace 

gases present in the atmosphere absorb incoming solar IR 

radiation. Concentrations of trace gases can be determined 

by measuring integrated areas of absorption lines and 

comparing these measured values to published line-strength 

data. Wallace and Livingston [1990a, b] have reanalyzed 

C01, CH4, N10, and CO spectra obtained at Kitt Peak during 

1979-1985 using the diatomic lines of oxygen as an internal 

standard to yield average atmospheric concentration values 

for these gases. 

69 

Spectroscopic C01 measurements made at Kitt Peak during 

1978-1989 yield a mean growth rate of 0.49% per year 
' ' .... '. - ... . '40-N 

Tahiti · -:- - E~fst'eY · · · -:- -· -· · -:· · · ' ' ' 

.' .lslaf.id . . ' 

I I • t 

- - - - - - - - - - - -- -- - - - - - --- - - - -

IR/TS891• I 

·, - - - . - . ; 40 s-. -

- - - - - -· - - - - - - _. - - - - - - J - - - - - -

120 V! 80 w 40 V/ 

Fig. 8.11 . Cruise track of the RrTS expedition in the eastern Pacific Ocean. 

whereas NWR flask air-sample data yield a mean C01 

growth rate of 0.48% (Figure 8.12a). There is a difference 

of - 10 ppm between the scales of the two measurement 

techniques, perhaps due to errors associated with the 

absolute line strengths or to differences in the features of the 

vertical profiles of 0 1 and C01 . A similar comparison of 

CH4 concentrations also shows a bias in the measurements 

e 

a. 

.s 

N 

0 

(.) 

~ 

i5 

a. 

I: 

~ 

390 

380 

370 

360 -

350 

340 

330 

320 

310 

78 

a 

80 

KITT PEAK 

82 8 4 

Time (year) 

400 

390 

6 

380 6 e 370 a. 

Si 

360 N 

0 

(.) 

350 ~ z 340 

330 

320 

86 88 90 

(-60 ppb), as well as a difference in growth rates that is not 

statistically significant. Data from Kitt Peak yield a growth 

rate of 1.01 % per year compared with 0.76% per year for the 

NWR data (Figure 8.12b). Although the NWR CH4 flask 

record began in 1983, air in cylinders was collected at NWR 

between 1977 and 1979, and was recently analyzed for CH4 • 

Including these new data and assuming a linear growth for 

1900 . 2000 

b 6 

:a 1800 

KITT PEAK flJoo ~ ~ 1900 

a. :a .s a. 

" Ji? .s :i:: " (.) 1700 1800 :i:: ~ 

6 0 0 

i5 "A 60.0:. 6

6 

a. ~ 

I: z 1600 1700 

~ 

1500 1600 

78 80 82 84 86 88 90 

Time (year) 

Fig. 8. 12. Comparisons of CMDL flask sample data from NWR (squares) with NSO data derived from IR spectra measured at Kitt Peak, 

Arizona (triangles) (a) C0 1 and (b) CH4. 

70 
the complete NWR ·record gives a calculated growth rate of 

-1 % per year, in good agreement with the spectrometric 

record. 

In early 1991 a CMDL Ff-IR spectrometer will be moved 

to the fifth floor of the building in Boulder. Operation of the 

spectrometer and archiving of spectra will begin in the 

summer of 1991 to complement observations made at Kitt 

Peak. 

8.2.3. AIRBORNE GAS CHROMATOGRAPH 

Testing of a Shimadzu Mini-2 gas chromatograph 

continued aboard the NOAA King Air research aircraft. 

Tylan mass flow controllers were used to maintain a steady 

carrier gas flow rate. In February N20 was measured in 

coal-fired power plant plumes near Miami, Florida. Np was also measured in the Pawnee Power Plant plume near 

Brush, Colorado (Figure 8.13) on July 28. Although data 

obtained during the flight were not as precise as station data, 

we did not detect parts per million levels of N20 in the 

plumes, and it was therefore concluded that combustion is a 

minor source of atmospheric N20. During the flight in the 

Pawnee Power Plant plume, air samples were collected in 

500 mL airbags for subsequent analyses. Before the flight, 

the stability of N20 in the airbags was examined over the 

course of 24 hours. The airbags proved to be a reliable and 

inexpensive method of collecting air samples for quick N20 

analysis. Flue gas samples were also collected at the power 

plant. 

High variability in the Np in-situ flight data was 

atLributed to changes in the ECD cell pressure. Because the 

ECD sensitivity increases with decreasing atmospheric 

pressure, an absolute backpressure regulator was subsequently installed on the ECD outlet to maintain a constant 

cell pressure. Two flights were then made over eastern 

Colorado on Septe~ber 7 and 8 during which CFC-11 was 

measured with the in-situ GC, and flask air samples were 

collected. With use of both the backpressure regulator and 

Tylan mass flow controllers, on-board CFC-11 measurements improved; results agreed with flask sample CFC-11 

concentrations as well as with the CFC-11 value obtained at 

our sampling site at NWR (Figure 8.14). 

:c 

Q. 

Q. 

q,. -

z 

310 

300 

8 

PaiYnee Power Pl~nt Qrush, Coloradp . . . . : + : . . . . 

~· " • + + :· ~ • + + 

• I ' ' • t 

~ -..!. ' :..... • ···············-···~-----···········-~·-·········! ..... . . . ' . ' ' . . ' ' ' ' ' : : + GC 

~ ~ •airbag . . 

9 10 11 

Local time (hour) 

Fig. 8. 13. Concentrations of N20 in the plume at the Pawnee Power 

Plant, Brush, Colorado, on July 28, 1989, derived from in-situ GC 

(pluses) and airbag sample (circles) measurements aboard the 

NOAA King-Air aircraft. 

300 -..----------------, 

b * 

::c 

E 

-

400 

500 

600 

700 

a • • ......................... ~ ................................... . 

i+~ ** 

...................... + ..··#··+·+··························· 

+• * ····················································-········· 

····························+···························· • " · * ••.••.•••. A ••••.•.•. . 

.,,, 

200 250 300 

CFC-11 (ppt) 

350 50000 70000 90000 

Response 

Fig. 8.14. CFC-I I concentrations measured over central Colorado September 8 and 9, 1989, aboard the NOAA King-Air aircraft. (a) Aircraft 

CFC-1 1 data obtained from in-situ GC measurements (pluses) and from flask air samples (triangles) are compared with NWR flask sample 

data (circle). (b) The relative response (peak height) of the in-situ GC while a gas standard was analyzed during thL flight. The relative 

standard deviation for measuring CFC-I I in the standard during the flight was better than 3.0%. 

71 
8.3. REFERENCES 

Butler, J.H., J.W. Elkins, T.M. Thompson, and K.B. Egan, 

Tropospheric and dissolved N20 of the west Pacific and cast 

Indian Oceans during the El Nino-Southern Oscillation event 

of 1987, J. Geophys. Ru., 94(Dl2), 14,865-14,877, 1989. 

Elkins, J.W., T.M. Thompson, B.D. Hall, K.B. Egan, and J.H. 

Butler, NOAA/GMCC halocarbons and nitrous oxide 

measurements at the South Pole, Ant. J. U. S., 23, 176-177, 

72 

1988. 

Wallace, L., and W. Livingston, Spectroscopic observations of 

atmospheric trace gases over Kitt Peak, 1, Carbon dioxide and 

methagc from 1979 to 1985, J. Geophys. Ru., 95(D7), 

9823-9827, 1990a. 

Wallace, L., and W. Livingston, Spectroscopic observations at 

atmospheric trace gases over Kitt Peale, 2, Nitrous oxide and 

carbon monoxide from 1979 to 1985, J. Geophys. Ru, 

95(Dl0), 16,383-16,390, 1990b. 
9. Director's Office 

9.1. A JOINT U.S./U.S.S.R. EXPERIMENT FOR 

THE STUDY OF DESERT DUST AND ITS 

IMPACT ON LOCAL METEOROLOGICAL 

CoNDmONS AND CLIMATE 

DALE A. GILLEITE 

9 .1.1. lN1RODUCTION 

A joint U.S./U.S.S.R. expedition to study the causes and 

effects of desert dust on the environment was carried out in 

Tadzhikistan, S.S.R .. in September 1989. The expedition was 

conducted under the auspices of the bilateral U.S./U.S.S.R. 

Working Group VIlI (Influence of Environmental Changes on 

Climate). Nine American scientists and one French scientist 

were led administratively by NOAA; 28 Soviet scientists were 

led by Academician George Golitsyn. Table 9.1 lists the U.S. 

participants, their institutions, and research topics. Equipment 

setup began at the individual sites on September 5, and 

measurements began on September 6 and continued until 

September 27, 1989. 

9.1.2. PURPOSE 

The purpose of the expedition was to measure desert dust 

production, to determine chemical and physical properties of the 

dust, and to assess the effects of the dust on meteorological 

conditions and climate. Characterization of physical properties 

of the dust focused on optical and radiative properties, while the 

chemical composition study focused on finding a possible 

interaction of the alkaline component of the dust with acidic 

components of gaseous and particulate air pollution in the city 

of Dushanbe. The experiment was designed to attempt to 

provide a mass balance of dust production, transport, and 

deposition in a watershed feeding the Aral Sea (the Kafimigan 

River Valley in Tadzhikistan south of Dushanbe; see Figure 9.1. 

Thus the experiment was a complete assessment of dust 

production by a desert and the climatic and environmental 

consequences of that dust. 

9.1.3. ACTIVITIES 

The Kaftrnigan River Valley is located within several deserts 

of Central Asia. The probability of rairtfall in the Shaartuz 

region of southwestern Tadzhikistan near the Amu Darya River 

is less than 1 day during June 1-September 1. Experiments 

concerned with aerodynamic, soil, optical, and chemical 

characteristics of the source region were conducted at site 1 (see 

Figure 9.1). This site is near the center of a local dust source 

area observed by officials of the village of Shaartuz. 

Micrometeorological measurements made at site 1 provided 

information on vertical fluxes of suspended dust. Special 

attention was paid to the aerodynamic partitioning of momentum between the abrading surface and nonerodible vegetation 

and the effect of the cryptogamic crusts observed in these desert 

soils. Specialists concerned with the effects of cryptogarnic 

TABLE 9.1 U. S. Investigators and Analyses to be Done 

Investigator 

D. Gillette 

(NOAA) 

J. Del..uisi 

(NOAA) 

B. Bodhaine 

(NOAA) 

D. MacKinnon 

(USGS) 

J. Dobrowolski 

(Utah St Univ.) 

E. Pauenon 

(Georgia Tedi.) 

J. Winchester 

(Florida St. Univ.) 

B. Musick 

(Univ. of New Mex.) 

L. Ganes 

(Univ. of Paris) 

P. StodclOn 

(Univ. of Colo.) 

Data Reduction/Analysis 

Transport modeling, momentum 

partitioning, dust size distributions, 

vertical mass flux, saltation flux, 

threshold velocities 

Optical depth, single scattering albedo, 

asymmetry parameter, aerosol mass 

in atmospheric column 

Time series of nephelometer 

Optical/radiative parameterization, 

remote sensing, mass flux of aerosol 

transport 

Cryptogamic soil crusting, soil 

properties/deposition 

Single scattering albedo, asymmetry 

parameter, size distribution of dust 

PIXE analysis of streakers, statistical 

analysis of PIXE data 

Vegetative/aerodynamic properties 

Siz.e/composition of aerosols 

Threshold velocity of dust 

crusts and desert vegetation and geology carefully surveyed the 

area and sampled soil, vegetation, and cryptogarnic crusts. Dust 

samples were collected to determine chemical composition and 

size distribution. Visibility, mass concentration, and solar 

photometer measurements, including optical thickness 

detennlnations, provided data for use in optical calculations, 

including optical thickness determinations. It is commonly 

believed that source regions in Afghanistan are responsible for 

producing much of the dust transported up the Kaftrnigan River 

Valley (hence the name for the dust-bearing wind, Afghanetz). 

One goal of the experiment was to find the strongest source of 

dust. 

Frequency mapping of dust storms showed that 10 to 30 dust 

storms are to be expected annually in southern Tadzhikistan just 

north of the Amu Darya River in the Kaftrnigan River Valley. 

The peak season for the storms is summer so one would expect 

dust storms to occur in early September, the time of the 

birtational experiment. Dominant summer winds blow directly 

up the river valley (from the south). We focused on conditions 

in the Kafimigan River Valley, from the Amu Darya River 

(Afghanistan border) to Dushanbe. As seen in Figure 9.1, the 

73 
,__. 0 15 30 45 

KM 

500 1000 1500 2000 ) 000 

. >J.n"IVtlo (!-'.! 

Fig 9.1. The experiment sites in the Kafimigan River Valley. Site 1 is 

Shaartu7; site 2 is Isenbai. 

river valley narrows from approximately 25 km in width at the 

Amu Darya to about 5 km near Dushanbe. The desert area at 

site 1 is in the most southerly part of the valley, an area of about 

700 kml. Micrometeorological measurements made near the 

center of this source area will be generalized to the entire desert 

area of the river valley from Amu Darya to Dushanbe. By using 

meteorological data provided by the Tadzhik Hydrometeorological Service, we specified parameters for a dust flux model to 

estimate dust fluxes to Dushanbe. 

To evaluate dust transport model estimates described above, 

we calculated dust flux estimates at a downwind location in the 

river valley. At this location, designated as site 2 in Figure 9.1, 

detailed measurements of optical properties along with solar 

photometry measurements were made to determine the total 

atmospheric column mass loading of aerosol being transported 

up the valley. Site 2 is at the village oflsenbai, within 70 km of 

Dushanbe in that part of the Kafimigan River Valley that is only 

about 15 km wide. There is no local dust production or local 

sources of urban pollution near this site. Average wind speed 

measured at site 2 provided a transport velocity to calculate 

mass flux for computations of the total mass concentration cross 

section of desert dust being transported up the Kafimigan Valley 

to Dushanbe. Measured optical and physical properties of the 

dust were used to calculate total atmospheric column dust 

masses from the solar photometer measureme!lts. Other 

physical and optical properties measured were single scattering 

albedo, asymmetry parameter, size distribution, and real and 

imaginary index of refraction. An integrating nephelometer was 

used to measure aerosol scattering extinction directly. 

Continuous measurements were made with the integrating 

nephelometer to establish a time series of aerosol data for the 

entire experimental time period. Filtration samples and 

automated "streaker" samples were obtained from aerosols 

during dust storm transport up the river valley. These samples 

were used for optical studies and chemical composition 

determinations. 

NOAA A VHRR satellite data were obtained for the 

experimental region and the time of the experiment. The 

ground-based optical, radiative, and aerosol mass flux data were 

used to interpret the remotely sensed satellite images before and 

during dust storms. 

Our third experiment site in the Kafimigan Valley was at the 

Tadzhik Physical Technical Institute in Dushanbe. The 

instrument used there was the "streaker" aerosol sampler 

designed to sample automatically and continuously during the 

experimental period. From data obtained. a continuous time 

series will be established for the aerosol composition for 

Dushanbe. Experimental evidence is being sought for the 

absorption of sulfur by the alkaline desert aerosol. The source 

of the sulfur would be urban air pollution produced at 

Dushanbe. The sulfur would be present as CaS04 , converted 

from S02 by reaction with CaC03 in the desert aerosol. 

Additional sampling by two other streakers at sites 1 and 2 was 

used to establish relationships of sulfur and the desert aerosol. 

9.1.4. SUMM:ARY 

The Kafimigan Valley Desert Dust Experiment was 

scientifically divided into five problem areas to encompass the 

work of the combined team of investigators. When taken 

together, these five areas give an integrated scientific picture of 

the causes and consequences of desert dust. The first concerned 

specification of the source area of the dust. Biological, physical, 

and chemical investigations were included in this specification. 

The second i.Qvolved. the. specification of the dust movement: 

flux of dust from the source area, flux of dust to the surface, and 

transport of dust by the wind (source/sink/transport). The third, 

which was extremely important, was the physical and .optical 

description of the dust. It includes one of the principal reasons 

for performing the experiment: to assess the climatic consequences of desert dust. The fourth dealt with the description of 

the chemistry of the dust, namely, its transformation and 

interaction with other aerosols and gases, especially those 

having pollution origin. The fifth concerned determining the 

large-scale structure of the dust storms sampled and synthesis of 

the system in models. 

Dust storms were experienced on September 16 and 20, 

1989. The first dust storm was smaller in magnitude' than the 

second. The storm of September 20 had winds of more than 20 

m s·• at desert site 1 and more than 7 m s·

1 at valley site 2; site 1 

was a source of dust for 58 minutes. The experiment was 

successful in providing data for all five problem areas. Analysis 

of the data is now under way, and a meeting concerned with the 

first results of the binational experiment will take place in 

Nalchi.k, U.S.S.R .. in September 1990. 

74 
9 .2. ANNUAL OZONE CYCLE AND DECADE 

TREND AT SOUTII PoLE 

R.C. SCHNELL. S.C. Lru (Atro110myLabora1<>ry),S.J. OLTMANS, 

R.S. STONE, DJ. HOFMANN, 

W.T. STURGES, E.G. DllITON, 

M. T'RAINER (Atronomy Laborat<>ry). AND J.M. HARRIS 

9.2.1. INTRODUCTION 

Surface ozone at South Pole, Antarctica, displays a distinct 

summer minimum having a significant downward trend, over 

the period 1976 to 1990. We suggest that the trend in summer 

ozone minima is caused by enhanced photochemical destruction 

of ozone in the lower troposphere due to the increased 

penetration of UV radiation associated with the stratospheric 

ozone hole. In addition, the trend in surface ozone is highly 

correlated with increased cloudiness over the same period, 

suggesting an influence of atmospheric dynamics. 

9.2.2. SEASONAL OZONE VARIATIONS AT SOUTH POLE 

The Jong-term surface ozone record al SPO was studied lo 

determine annual and long-term patterns. Figure 9.2a shows the 

CMDL hourly average ozone data from SPO (2.8 km MSL), 

averaged weekly for 1981-1987. Figure 9.2b shows the 

corresponding mean daily solar radiation measured at the 

surface at SPO, and modeled for South Pole, McMurdo 

(77.9'S), and the Antarctic Circle. As the sun rises at the pole in 

late Seplember, ozone begins a period of decline and greater 

variability, which continues until austral sunset. At that time, 

ozone begins a steady recovery, pea.king in July and August. 

Th.is negative correlation between surface ozone concentration 

and solar radiation suggests that tropospheric ozone is being 

photochemically destroyed seasonally in the Antarctic as it is in 

the Arctic [Ollman.s et al., 1989]. 

At SPO, decline in ozone begins around the middle of 

September, but significant solar radiation levels needed to 

initiate the classic low NO. ozone destruction reaction are not 

reached at the pole until mid-October. Ample solar radiation 

amounts are, however, seen at the Antarctic Circle by early 

September, suggesting that the springtime ozone depletion 

observed at SPO has its origin at lower latitudes and is 

subsequently transported to the pole. Isobaric back trajectories 

on the 500-mb surface were examined for September-December 

1987. During each month, numerous trajectories indicated 

Jong-range transport from north of 75'S within 2.5 days. 

Moreover, transport from north of 65'S in 2.5 days was not 

uncommon. 

Evidence of effective meridional flow to SPO can also be 

seen in a representative austral summer ozone depletion event 

measured at SPO and the coincident air temperature time series, 

presented in Figure 9.3. A 1986 ozone depletion event 

beginning on day 339 and ending on day 344 is correlated with 

the intrusion of a warm ai.r mass. This ozone depletion event 

was associated with much warmer air temperatures, overcast 

skies, and elevated sea salt concentrations, suggesting the 

presence of marine air transported inland from a coastal region. 

"~ -------------~------.., 

a 

=.1..,....JC.....,.- 0 2 , 6 -~~ e 10 12 H -~15 II io ~-22 2t ~.,.....,~-- 26 28 lO ll lt 36 J!) tO --~---' t2 \t 1°6 ta s.o S2 

h[[~ 

J~·· fES r.

0 R N'R MY M .M. AUG SEP CCT •• ~v OcC 

MONTH 

Fig. 9.2.(a) Box and whisker plots showing lhe seasonal mean surface 

ozone cycle and variability at South Pole for January 1981 to December 

1987. The median (dot), the upper and lower quaniles (ends of lhe 

boxes), and upper and lower fifth percentiles (ends of the whiskers) of 

wcckJy average ozone values arc shown. (b) Observed daily mean 

global solar radiation at South Pole (dots) and modeled clear-sky solar. 

radiation at McMurdo, at the latitude of lhe Antarctic Circle, and at the 

Soulh Pole. 

Such marine air intrusion events have been shown to occur 

regularly at South Pole [Bodhaine et al., 1986]. These events at 

SPO are consistent with the notion that the seasonal depletion of 

ozone first occurs in the lower troposphere at lower latitudes and 

that ozone-depleted air is subsequently transported inland. 

9.2.3. LONG-TERM DECREASING OZONE TREND AT 

SOUTH POLE 

The SPO ozone record from 1975 to 1989 (Figure 9.4) shows 

a statistically significant downward trend in the near-surface 

ozone concentration for the austral summer months (December, 

January, February, and March). The decrease is about J 7% over 

the 14-year period, or a rate of about 0.32 ppbv annually when 

fitted linearly. No statistically significant trend can be found for 

other seasons. However, a closer examination of these data 

suggests that a tendency toward a small ozone decrease is first 

75 
-18,--~--~-~--~-~--~-~---+40 

- 18 

,--...-20 

u 

0 

--22 

Q) 

5-24 

_, 

~ -26 

Q) 

0.-28 

E 

~ -30 

-321 

38 

32'.Q 

0. 

0. 

28 '-' 

Q) 

i:: 

0 24 N 

0 

20 

34 +---.--.-----.---.- -.---.--~---1-1e 

JJS JJ9 J<O J4 I J 42 J4J JH J45 J46 

Day of Year 

Fig. 9.3. South Pole surface orone conccntratioru and the nur-surfacc 

air temperature record, for December 4-11, 1986 (austral summer). 

40 

30 

20 

40 

,.-..._ 30 

,D 

0.. 

0.. 

..__, 20 

JUL . • • •• • • ••• . . • • 

• 

OCT • • • 

~ 

• 

. ·· ~ 

~ 

z 

0 

N 

40 JAN 

0 30 

20 

40 APR 

• • • 30 

~ • r-. -

20 

AUG • • SEP 

----===- ~ 

• 

------- _. . • 

NOV DEC 

~ 

• 

~ 

....... ~ . ~ ~ • • 

FEB MAR 

• 

~ 

• • 

MAY JUN 

• _..,_. · • • . - .... · ~ 

r - -

• 

75777981 83 858789 7577798183851719 75777911138517 89 

YEAR 

Fig. 9.4. Mean surface oi.ooe mixing ratios by month for 1975-1989. 

The solid line is a linear least-squares fu to the data for each month. 

The dotted lines arc 9S% confidence intervals for the trend lines. The 

December, January, Febr111ry, and March trends arc significant at the 

95% level. 

detected in October, reaches a maximwn decreasing rate during 

January, and completely disappears by May. The seasonal 

pattern (Figure 9.2a), with the surface ozone minimwn during 

the austral swnmer, is similar to the seasonal pattern in the 

long-term trend that shows the largest decreases occurring 

during the swnmer months. This suggests that photochemical 

processes are important both in the seasonal cycle and in the 

long term. 

The downward trend in the mean January-February solar 

irradiance is well correlated with a downward trend in surface 

ozone concentrations measured at the pole, as shown in Figure 

9.5. The observed sky cover for South Pole from 1957 to 1990 

is shown in the insert (Figure 9.5). A trend to increased 

cloudiness in the last decade of the record is apparent The data 

in Figure 9 .5 suggest that ozone-depleted air transported from 

lower latitudes contributes significantly to the surface ozone loss 

during the late austral sw:nmer months at South Pole. However, 

an examination of the solar irradiance data by month shows that 

the significant downward trend in solar irra.diance exists only in 

January and February, whereas the decrease of surface orone 

appears to start as early as October and lasts until the end of 

April (Figure 9.4). Thus, although the transport mechanism 

may contribute significantly to the observed downward trend in 

tropospheric ozone during January and February, it appears it is 

not the major contributor during other months . 

9.2.4. SUMMARY AND CONCLUSIONS 

An austral summer surface ozone minimum with a significant 

long-term decreasing trend (1.13% yrl during 1976 to 1990) has 

been documented at SPO. The seasonal variation is most likely 

76 

b 

llO 

~!" \t"JJ 26 ;:; 

!: • 

.. - 25 

E l ~ .. 300 ; H "" ~ 

4 

w --- ~ 25 ..0 

u )9 u .. to " ,. u 

.. "! \ 0. 

z HU 0. 

< 290 22 0 w < z c: 21 0 c: ;. N 

0 

c: 280 JAN- FEB TRENDS 20 -- _, 

< AT SOUTH POLE --- 0 --"""'··· IRRADIANCE 19 (/) ---0-- OZONE: 

270 18 

75 76 77 78 79 80 81 82 8l 84 85 86 87 88 89 90 

YEAR 

Fig. 9.S(a) Mean January-February surface ozone concentrations and 

linear trend line for 1976-1990 (connected docs and solid line referenced 

to right scale) compared with the mean January-Febr111ry solar 

irradiance (measurements initiated in 1976) flux measured at the South 

Pole (triangles referenced to left scale). The trend in solar irradiancc for 

the 14-ycar period is represented by the dashed line, which is 

anticorrclated with observed cloudiness at the South Pole. (b) The 

long-term record of South Pole sky cover (since 1957) for JanuaryFebruary. A 15% lowess smoothing function was applied to the 

monthly averages of multiple (up to 24) observations. 
associated with increased photochemical ozone destruction due 

to the annual increase in solar radiation at that time, the 

transport of ozone-depleted air from lower latitudes accounting 

for the early springtime onset of the reduction. 

The decreasing trend in summer surface ozone at SPO since 

1979 is very likely the result of enhanced photochemical 

destruction of ozone in the lower troposphere due to increased 

penetration of UV radiation associated with the stratospheric 

ozone hole. The solar irradiance at South Pole, which is 

inversely proportional to the cloudiness caused by inflow of 

marine air to South Pole, also shows a significant downward 

trend for January and February over the same period. This trend 

correlates very well with the downward trend in ozone 

concentrations. 

9.3. WINTERTIME BLACK CARBON AEROSOL 

MEASUREMENTS OVER TIIE SOUTIIWESTERN 

UNITED ST A TES, DECEMBER 1989 

PATRICKJ. SHERIDAN,RUSSELLC. SCHNELL, 

AND JOE F. BOATMAN 

9 .3.1. INTRODUCTION 

This experiment is the third in a series designed to characterize the aerosol over the high desert of south<entral New 

Mexico and to document aerosol variability as a function of 

season. atmospheric flow patterns, and altitude of collection. 

The two previous aircraft-based aerosol sampling missions were 

conducted in May and July 1989. The field experiment 

documented in this paper will be referred to as ALIVE-3 (the 

third Atmospheric Lidar Validation Experiment). 

Sampling procedures were similar to those used in the 

previous experiments. Unlike in the earlier studies, however, 

high concentrations of carbonaceous particles were observed in 

many ALIVE-3 cascade impactor samples. This paper describes 

cascade impactor aerosol carbon measurements collected during 

the ALIVE-3 flights and concurrent bulk aerosol black C 

measurements. Our attempts to correlate the bulk and 

individual-particle aerosol C data are discussed. 

9.3.2. EXPERIMENTAL METHODS 

Aerosol samples were collected by aircraft over New Mexico 

during December 11-15, 1989. The research platform for this 

study was the NOAA King Air aircraft operated by the Air 

Resources Laboratory. As in the earlier programs, care was 

taken in this program to limit the lengths and bending of tubing 

upstream of our aerosol samplers so that particle losses would 

be kept to a minimum. No evidence was found (e.g., the total 

absence of very large or very small particles, or obvious 

particulate contamination) that would lead one to believe that 

sampling was biased in some way relative to the previous 

experiments. 

Cascade impactor aerosol samples were collected at 

predetermined altitudes in the sampling area. For each flight, 

one low-altitude aerosol sample (within the PBL) and one 

high-altitude sample (above the PBL) were collected. The 

samplers were five-stage PIXE Corporation cascade impactors. 

Particles were collected directly onto thin (10-20 nm thick) 

Formvar films supported by Ni TEM grids. The grids were 

commercially prepared in clean-room facilities and were 

checked for possible contamination before use. 

An AEM was employed to obtain information on individual 

particle chemistry and morphology and on the aerosol size 

distribution [Sheridan, 1989a]. An ultrathin window x-ray 

spectrometer interfaced with the microscope permitted the 

detection of x-rays more energetic (i.e, from heavier elements) 

than those of Be. Thus, the interesting light elements C and 0 

(and occasionally N) were directly observable in discrete 

particles. High-resolution photomicrographs were taken of 

individual particles and particulate deposits on films from all 

analyzed stages. 

Characterization of the fine fraction of the aerosol collected 

during ALIVE-3 was performed by AEM of particles on the 

stage 1 (0.25-μm aerodynamic cutoff diameter) films. 

Preliminary characterization for each sample included counting 

and classifying all particles within a finite area (a rectangle on 

the viewing screen of the electron microscope) on a film portion 

directly under the impactor jet. Analysis of this central aerosol 

deposit continued until at least 300 particles were counted and 

resulted in the determination of approximate relative loadings on 

the films, which, since collected volumes were similar for all 

samples, reflect relative particle concentrations in the atmosphere. 

Aerosol black C measurements were made continuously and 

in real time onboard the King Air aircraft over a wide range of 

altitudes. An aethalometer was used to collect the aerosol and 

to convert aerosol extinction to black C concentrations [Hansen, 

1991]. Vertical profiles of aerosol black C concentration were 

then constructed over the study area. 

9.3.3. RESULTS AND DISCUSSION 

The results of the individual-particle analysis portion of this 

study are based on fine-particle (stage 1) data, which we know 

from previous work contains most of the aerosol C information 

[Sheridan, 1986]. The majority of superrnicrometer particles 

collected on coarse-fraction impactor stages resembled various 

types of soil dust, a finding that is consistent with previous 

aerosol studies in this region [Sheridan, l 989a, b]. Recent 

studies show that the soil component is responsible for only a 

small fraction of the total optical extinction in the visible and 

near-infrared spectral regions [Hansen, 1991]. 

The composition of the fine aerosol was quite variable during 

the experiment. The stage 1 aerosol samples collected during 

ALIVE-3 have been classified as one of three major types. 

Aerosol class 1 consisted primarily of fine, solid (NH4)

2S04 

particles. In this class of aerosol sample, >80% (sometimes as 

high as 95%) of the total number of analyzed particles were 

solid (i.e., neutralized) sulfates. 

77 

The second major type of aerosol (aerosol class 2) contained 

a significant number fraction (15-51 %) of small, spherical 

C-rich (SC) particles externally mixed with the sulfates. These 

C-rich spheres ranged between -0.05 and - 1.0 μm in diameter, 

and had a median size of about 0.2 μm. This type of aerosol 
was observed most frequently in low-altitude samples collected 

during the last half of the experiment (December 13-15). 

Scientists aboard the aircraft visually confirmed the El Paso 

urban plume in the research area at this time [Gun/er et al., 

1991]. The compositions of the aerosol samples collected on 

these days suggest increased wintertime combustion activities in 

the El Paso area as likely aerosol sources. This macroclass of 

aerosol was not observed in our two previous (late spring and 

suinmer) ALIVE electron microscope aerosol studies, where 

generally -1 % or less of the stage 1 particles were found to be 

C-rich with an obvious combustion (i.e., spherical) morphology. 

The third type of aerosol (aerosol class 3) consisted of a large 

number fraction (near 50%) of nonspherical C-rich (NSC) 

particles. Particles of this type were observed in the previous 

ALIVE aerosol studies, but again in much smaller numbers. 

These particles were classified as "non-combustion C" in past 

reports [Sheridan, l 989a, b], but may actually be combustionderived black C resulting from a sour~e w\th a lo.wer combustion temperature and/or a different fuel mix than that of 

spherical combustion C particles. Concurrent aethalometer 

measurements suggest that this might indeed be the case 

[Gunter et al., 1991]. The various morphologies of C-rich 

particles collected during the ALIVE-3 flights are shown in 

Figure 9.6 

Sixteen of the eighteen fine aerosol samples collected during 

ALIVE-3 fit into one of the three general categories described 

above. The two anomalous samples had moderate fractions of 

C-rich particles (23% of all analyzed particles in both samples 

were SC and/or NSC), but not large enough fractions of either 

discrete type to fit the definition of the "significant SC" or 

"significant NSC" aerosol classes. 

' 

# • . ~ 

~ ,· 

. ·.• .. .. 

• ' • 

. • . 

Other major particle types that were less frequently observed 

in the fine aerosols included liquid (acidic) sulfate, soil dust, 

composite sulfate/crustal, composite carbonaceous/crustal, 

Na/Cl-rich, K/Cl-rich, and rounded-to-spherical Fe-, Ti-, Feffiand Zn-rich particles. These types of particles collectively 

constituted <10% of the fine aerosol particles on all stage 1 

films. 

The individual particle aerosol data were compared with 

concurrent aethalometer data to determine if trends in the bulk 

aerosol black C concentrations are observable through 

microanalysis of the aerosol. Table 9.2 shows the fractions of 

SC and NSC particles, along with the sum of these values 

representing a total C (TC) fraction. Concurrent black C 

aethalometer measurements for the December flights were taken 

from the King Air vertical profiles [Gunter et al., 1991] and are 

listed next to the microanalysis data. It was initially assumed 

that if a high correlation between the bulk and individualparticle data existed, it would be most obvious when comparing 

the aethalometer and SC (i.e., combustion) particle data. 

However, a quick inspection of the electron microscope data 

shows that NSC data relate much better to aethalometer 

measurements for the first two samples than do the SC data. 

It is also apparent that aethalometer measurements are 

inherently dependent not only on aerosol composition but also 

on aerosol mass (or filter loading). A load factor (LF), directly 

proportional to the particulate loading on each grid, was 

calculated by coWlting all particles within a finite area on the 

most heavily loaded portion of the stage 1 films. Multiplying 

the fraction of NSC, SC, and TC particles by this LF creates 

dimensionless parameters (columns 8-10) that reflect both 

aerosol composition and mass. We expected these parameters, 

O.lpm 

. ... 

Fig. 9.6. Different morphologies of carbonaceous particles collected during the AUVE-3 flights. (a) Small C-rich spheres observed in abundance in 

low-altitude samples during December 13-15. (b) Heavy loadings of nonspherical C-rich particles found in samples I and 2. (c) A carbonaceous 

chain aggregate particle. These larger combustion-derived particles were infrequently observed in most samples. (<i) High-magnification field of view 

of the two types of combustion-morphology black C particles. 

78 
TABLE9.2. Carbonaceous Fine-Particle Fractions and Load Factor Data From the Final Stage of the ALIYE-3 Cascade 

Impactor Samples, and Concurrent Aethalometer Black C Measurements for Comparison 

Aethalorneter 

Sampling Black C, 

Sample No. Level ngm·3 NSC SC TC LF WNSC wsc WTC 

1 L 210 0.49 0.0'2 0.51 7 3.43 0.14 3.57 

2 H 245 0.54 O.D3 0.57 17 9.18 0.51 9.69 

3 L 115 O.D7 O.D7 0.14 4 0.28 0.28 0.64 

4 H 65 0.12 0.03 0.15 6 0.72 0.18 0.90 

5 L ND 0.0'2 0.0'2 0.04 5 0.10 0.10 0.20 

6 H ND 0.19 0.04 0.23 8 1.52 0.32 1.84 

7 L 150 0.11 0.04 0.15 5 0.55 0.20 0.75 

8 H 100 0.0') 0.05 0.14 5 0.45 0.25 0.70 

9 L 90 0.04 0.05 0.0') 5 0.20 0.25 0.45 

10 H 60 O.D7 0.17 0.24 4 0.28 0.68 0,96 

11 L 238 0.06 0.23 0.29 6 0.36 1.38 1.74 

12 H 105 0.13 0.10 0.23 5 0.65 0.50 1.15 

13 L 75 0.05 0.19 0.24 4 0.20 0.76 0.96 

14 H 50 0.06 0.04 0.10 4 0.24 0.16 0.40 

15 L 275 0.14 II 0.51 0.65 6 0.84 3.06 3.90 

16 H 45 0.04 0.19 0.23 3 0.12 0.57 0.69 

17 L 195 0.05 0.39 0.44 6 0.30 2.34 2.64 

18 H 75 0.03 0.15 0.18 5 0.15 0.75 0.90 

NSC = nonspherical C-rich particles; SC= spherical C-rich particles; TC= total carbon fraction; LF =load factor; WNSC = weighted NSC; WSC = 

weighted SC; WTC = weighled TC; L = samples oollecled at --6500 ft ASL; H = samples collected at -9500 ft ASL; ND= no data. 

especially the weighted SC (WSC, column 9) and weighted TC 

(WTC, column 10), to correlate best with bullc aerosol black C 

measurements. 

A linear least-squares fit was performed for each 

microanalytical parameter against the aethalometer data. The 

correlations for the 16 aethalometer measurements (a malfunction on December 12 resulted in no concurrent aethalometer 

data for two of the samples) and the appropriate electron 

microscope data are presented in Table 9.3. For the first three 

correlations, which compare the aethalometer data with the 

fractions of NSC, SC, and TC particles on stage 1 films, the data 

show a strong correlation between TC and the bulk aerosol 

black C measurements (rTC = 0.83). The fact that the TC versus 

aethalometer correlation is so much stronger than the SC versus 

aethalometer correlation is surprising, since SC (thought to be 

combustion C) is presumably what the aethalometer measures. 

The TC versus aethalometer data comparison, however, is 

bolstered by the relationships in samples 1 and 2. These heavy 

deposits of NSC particles probably contained significant 

amounts of nonspherical black C, which the aethalometer 

detected. If samples l and 2 are ignored, the correlation 

coefficients for TC versus aethalometer and SC versus 

aethalometer change to 0.76 and 0.71, respectively. 

The correlation between LF and the aethalometer data in 

Table 9.3 is not so strong, but suggests that aerosol loading 

alone on filters plays some role in aerosol extinction measurements. This contention is further supported by the comparisons 

between aethalometer data and the dimensionless parameters 

WNSC, WSC, and WTC. Incorporation of the LF into these 

parameters improves the correlation between the aethalometer 

79 

TABLE 9.3. Comparison of Electron Microscope 

Individual-Particle Data with Concurrent 

Aethalometer Black C Measurements 

Comparison 

Aethalometer versus NSC 

Aethalometer versus SC 

Aethalometer versus TC 

Aethalometer versus LF 

Aethalometer versus WNSC 

Aethalometer versus WSC 

Aethalometer versus WTC 

Correlation 

(r) 

0.55 

0.43 

0.83 

0.59 

0.51 

0.58 

0.71 

Correlation coefficients result from linear least-squares fits of the data. 

measurements and SC from rsc = 0.43 to rwsc = 0.58. The 

correlation between TC and aethalometer data is weakened by 

factoring in the LF (rTc = 0.83; rwrc = 0.71), but this is 

primarily due to the extremely heavy loading of C-rich particles 

in sample 2 that is not supported by a correspondingly large 

black C measurement 

Overall, the correlations between the individual-particle and 

bulk aerosol data are impressive, and show that at least the 

heavy episodes of black C aerosol detected by the aethalometer 

are observable using microanalytical techniques. Much of the 

variation between the data sets occurred during episodes of 

lower black C concentrations, which are not as easily detected 
using electron microscopy as are the high-concentration 

samples. Weaker correlation coefficients might be expected, 

considering the facts that (1) the cascade impactor samples 

were collected for - 10-min periods while the aircraft flew 

through horizontal inhomogeneities in the aerosol over a 

sampling area of several hundred square kilometers, and (2) 

the two sampling inlets were of similar, but not identical, size 

and shape and probably passed different fractions of the 

aerosol to the internal aerosol collectors. Correlation 

coefficients in the 0.6-0.8 range are noteworthy for the 

comparison of these very different types of measurements. 

Other studies [e.g., Sheridan, 1986] have concluded that direct 

comparisons of simultaneously-collected bulk aerosol and 

individual-particle data often show much worse correlations 

(r <0.5) than were found in the present study. 

At least two explanations are possible for the TC parameter 

comparing better with aethalometer data than did the SC (soot) 

parameter. Either the aethalometer is sensitive to optical 

extinction by aerosol other than black C, or the irregular 

C-rich aerosol collected primarily in samples 1 and 2 was 

composed significantly of black C. The morphologies. of these 

particles are not what we normally expect for sooty C, but 

perhaps a lower-temperature combustion process that produces 

a large fraction of nonspherical soot was the source. Whatever 

the source of these particles was, it is clear that the 

aethalometer gave a strong signal for black C aerosol at this 

time. This is the first time to our knowledge that direct 

comparisons of this type for black C aerosol have been made; 

answers to some of the questions generated here will 

undoubtedly require further study. 

80 

Aclawwltdgme"'3. We thank Dennis Garvey and the U.S. Anny 

Atmocpheric Sciences Laboratory (White Sands Missile Range) for the 

funding bf much of this worit. We a!Jo acknowledge mcrnben of the 

NOAA Air Quality Group, especially Dennis Wellman, Laureen Gunter, 

and Stan Wilkison for assistance in aircraft installation and sample 

collection. 

9.4. REFERENCES 

Bodhaine, B.A., J.J. DeLuisi, and J.M. Harris, Aerosol mcarurcmenu at 

the South Pole, Tel/us, 38B, 223-235, 1986. 

Gunter, L, J.F. Boatman, M. Luria, J. Ray, H. Si~ering, B. Watkins, 

and C. Van Valin, Report to U.S. Anny Atmospheric Sciences 

Laboratory at ALIVE-3 flight operations, in preparation, NOAA 

ARL Air Quaity Group, Boulder, CO, 1991. 

Hansen, A.D.A., Report to U.S. Anny Atmospheric Sciences Laboratory 

on aethalc:meter black carbon mcasuremenu during ALIVE-3, in 

preparation, Lawrence Berlcelcy Laboratories, Berlcelcy, CA, 1991. 

Oltmans, S.J., R.C. Schnell, PJ. Sheridan, R.E. Peterson, S.-M. U. J.W. 

Winchester, P.P. Tans, W.T. Sturges, J.D. Kahl, and LA. Barrie, 

Seuonal surface ozone and filterable bromine relatioo1hip1 in the 

high Arctic, Atmos. Environ., 23, 2431-2441, 1989. 

Sheridan, P J., The use of analytical electroo microlCOpY for the 

individual particle analysis of the Arctic hue aerosol, Ph.D. 

dissertatioo, University of Maryland, College Park, December 1986. 

Sheridan, P.J., Analytical electron micl'OICOpC analysis of aerosol 

sampled over White Sanda Missile Range, New Mexico, May 3-4, 

1989, Final Report to the U.S. Anny Atmospheric Sciences 

Laboratory, Cooperative Irutihlte for Research in Environmental 

Sciences, Boulder, CO, 25 pp., 1989a 

Sheridan, P.J., Analytical electron rnicroccope analysis of aerocol 

sampled over White Sands Missile Range, New Mexico, July 10-14, 

1989, Final Report to the U.S. Anny Atmospheric Sciencea 

Laboratory, Cooperative Irutihlte for Research in Environmental 

Sciences, Boulder, CO, 30 pp., 1989b. 
10. Cooperative Programs 

Precipitation Chemistry 

R.S. ARTZ 

NOAA, Air Resources Laboratory, Silver Spring, Maryland 20910 

1. INTRODUCTION 

Precipitation chemistry measurements continued generally 

unchanged at the four CMDL stations and at twelve regional 

stations. Several changes were instituted in two regional 

programs as a result of the completion of an additional 

statistical intercomparison, and work continues in restructuring the CMDL program. 

2. CMDL BASELINE MEASUREMENTS 

CMDL bimonthly chemistry measurements of snow 

samples continued normally at both BRW and SPO. At 

SMO, collection continued using the Aerochem Metrics 

sampler. Analysis results from the 1989 CMDL samples are 

not yet available. 

Sampling on the Island of Hawaii continued only at MLO; 

Hilo and 22 Mile Site collections were suspended pending 

the outcome of quality assurance tests using the funnel and 

bottle collectors. (Previous comparison of CMDL MLO data 

with University of Virginia Aerochem Metrics data indicated 

problems of acidification resulting from the use of the funnel 

and bottle collectors.) MLO CMDL data for 1989 are not 

available for additional comparisons. 

3. NADP REGIONAL BASELINE MEASUREMENTS 

NADP [1990] measurements continued normally at MLO, 

SMO, and 12 regional stations. As a result of a second 

statistical intercomparison conducted for stations in 

Mississippi, the Meridian station was closed. A replacement 

station was found for the Salem, Illinois, station closed in 

December 1988, just outside of the nearby town of Omega. 

Current plans are to include the NADP station in Puerto Rico 

as part of the NOAA precipitation chemistry network, 

beginning in FY 1990 or early in FY 1991. 

4. NADP MLO AND SMO 1989 PRECIPITATION 

CHEMISTRY DATA 

As noted in previous years, precipitation at MLO is 

mainly a very dilute solution of sulfuric acid and little else 

for most samples. Figure 1 shows that although the vast 

majority of samples have so; and H+ concentrations of 

approximately 20 μeq L·1 or less, concentrations in excess of 

60 μeq L·1 are occasionally observed in weekly samples. 

Also note from Figure 1 that so: concentrations tend to 

exceed H+ concentrations, a condition not typically observed 

in continental North American precipitation. A more careful 

81 

'O 

~ <D 

r:T 

! 0 

+ 

J: 

z ' 0 0 ,. 00 i== '<t 

< a: 

.... 

z 

UJ 

(.) 

z 

0 0 0 (.) N 

0 

0 

0 0 

0 20 40 60 80 

CONCENTRATION so; (μeq L'1

) 

Fig. I. NADP concen1rations of hydrogen ion versus sulfate at 

MLO, 1989. Note that sulfate concentrations are typically larger 

than laboratory hydrogen ion concentrations. 

study of this condition indicates that cation to anion balances 

are always close to unity (or as in Figure 2, cation minus 

values are near zero) when so; concentrations are low. 

Conversely, ion balances may be very poor when so; values 

are large, suggesting that unmeasured cations frequently 

exist in 'samples having high so;. 

Figure 3 shows that the marine influence on MLO 

precipitation is typically very small. Na+ and Cl· concentrations are in most cases less than 5 μ eq L-1 and the excess 

(non-seasalt) CI· concentrations (calculated using Na+ 

concentration) are always less than approximately 3 μeq L·I. 

Of note in Figure 3, however, are the three samples with 

relatively high concentrations of Na•, which result in an 

overcorrection of seasalt CI-. This indicates that the samples 

may have been contaminated with additional Na+, or more 

likely, that a small terrestrial source of Na+ also exists. 

Sample number 31 appears to be from an event that was 

substantially influenced by marine source regions. 

Figure 4 compares NADP laboratory and field H+ 

concentrations for SMO, 1989. Note that in all cases (except 

for one outlier, not shown) the H+ values are no higher than 

approximately 18 μeq L- 1• Also note that with rare 
10 

70 

10 

;_, •O 

er 

.. .. .:'; 

z 

0 30 

j:: 20 < 

a: 

..... 10 

z 

UJ 

u 

z 

0 -10 

u -20 

-30 

-&O 

I 11 I] 15 17 II 21 2J 2' 27 2' ll ll JS 

- CATIONS·ANIONS CS::sl soi- CONCENTRATION 

Fig. 2. NADP sulfate concentrations and cation minus anion values 

at MLO, 1989. The ion differences are nearly zero when sulfate 

concentrations are low, but high sulfate concentrations typically 

occur during weeks when ion differences are negative. Negative ion 

differences may indicate the existence of unmeasured cations. 

00000 Na + >H<-++-IH< Cl- 20 ••••• Cl-,, 

.:., 0 r::r 0 

! 

z 10 0 0 ~ 

< er 

I-: z 

w 

u 

z 

0 

u 0 

10-1-.~~~~~~~~ ~~~~~~~~~~-r-rl 

0 5 10 15 20 25 30 

SAMPLE IJUMBER (WEEKS) 

3 5 40 

Fig. 3. NADP concentrations of sodium, chloride, and excess 

(non-seasalt) chloride at MLO, 1989. 

20 

-- Loborolory H+ 

OJII] Field H+ 0 

0 

15 

.:., 

CT 

! 

z 

0 

~ ~ 0 

< 10 er 0 o ca 0 I- 0 z 

w 

u 

z 

0 

u 

5 

10 20 30 40 50 60 

SAMPLE NUMBER (WEEl<S) 

Fig. 4. NADP laboratory and field hydrogen ion concentrations at 

SMO, 1989. Differences may be due to the disappearance of the 

organic acids over time or the effects of contamination from the 

bucket lid 0-ring . 

exception, the laboratory values are lower than the field 

values. This is common in precipitation chemistry samples, 

indicating the disappearance of the organic acids over time 

and possibly the effects of some contamination from the 

bucket lid 0-ring. Other data from SMO indicate that the 

extremely low background values routinely observed in 

weekly samples are essentially unchanged from past years. 

5 .. REFERENCE 

National Atmospheric Deposition Program, NADPINTN Annual 

Data Summary, Precipitation Chemistry in the United Sta/ts, 

1989, Natural Resource Ecology Laboratory, Colorado State 

University, Fort Collins. 1990. 

82 
Continuous Aerosol Monitoring with the Epiphaniometer at MLO 

U. BALTENSPERGER,l H.W. GAEGGELER, AND D.T. ]OST 

Paw Scherrer b1.sti1uu, CH-5232 Villig~n PSI, Swilurland 

In December 1989, an epiphaniometer was installed at 

MLO. This instrument was developed recently [Giiggeler et 

al., 1989] and has the ability for continuous aerosol 

monitoring even at very low aerosol concentrations 

[Baltensperger et al., 1990]. 

The system is described in detail by Giiggeler et al. [1989]. 

A schematic diagram is shown in Figure 1. Aerosols are 

pumped through a chamber containing radioactive lead 

isotopes (211Pb). These single lead atoms are produced at a 

constant rate by the decay of a short-lived radon isotope 

(219Rn) emanating from a Jong-lived actinium source (2Z1 Ac). 

21 l Pb atoms attached to aerosol particles are transported 

through a capillary that acts as a diffusion barrier for nonattached lead atoms. At the end of the capillary, the aerosol 

particles and with them the attached lead atoms, are deposited 

on a filter. The resulting activity on the filter is measured 

continuously by a surface barrier detector by means of the 

a-decay of the bismuth isotope 211Bi, the daughter of 211Pb. 

Because of the relatively short half-life of 211Pb, aerosols can 

Air-- ===:::;i Capillary 

227Ac Source 

,_, 

EH13 '"'---"''CPU & 

EEB3 Data 

Mic roterminal 

Seria l Output-------1 

l.4emary 

be continuously monitored by the epiphaniometer, without 

changing or transporting the filter. 

Calibration experiments with artificial aerosols showed that 

the attachment coefficient of the 211 Pb atoms can be described 

by the Fuchs theory of coagulation [Fuchs, 1964; Seinfeld, 

1986]. Since the device delivers a signal that is proportional 

to the "Fuchs surface" of the aerosol particles [Guggeler et al., 

1989] it was called epiphaniometer (Greek epiphania = surface 

of a body). According to Fuchs, at small aerodynamic 

diameters (d < 100 nm, free molecular regime) the epiphaniometer signal is proportional to d2. At large aerodynamic 

diameters (>3 μm, hydrodynamic regime) the signal is 

proportional to d. In the intermediate regime, the obtained 

signal is proportional to dx, with x varying between 1 and 2, 

depending on particle diameter. Therefore, for a polydisperse 

aerosol, the obtained signal is proportional to the integral of 

the differential products dN • dS, with N = particle concentration and S = "Fuchs surface" = Tt • d•. Thus, the size 

distribution of an aerosol has to be known in order to calculate 

ex - Detector 

Temperature 

Filter 

Analog 

1/0 

Meter 

-out 

~otar 

Control 

Fig. 1. Schematic diagram of the epiphaniometer. 

I Present address: Department of Oiemical F.ngineering, California 

Institute of Technology, Pasadena, California 91125. 

83 
60000 

50000 

·= E 40000 

0 

C"l 

~ 30000 

c.. 

en 

.. 

§ 20000 

0 

u 

10000 

19 20 21 22 23 24 25 26 27 28 29 30 31 

Date (December 1989, CUT) 

Fig. 2. First epiphaniometer data from MLO for December 1989. 

the geometrical surface or the volume concentration. Despite 

this limitation, the epiphaniometer is well suited for aerosol 

monitoring. Its excellent sensitivity allows for measurements 

also at very low concentrations 'found, for example, at 

high-alpine sites. Because of the low flow rate of 1 L min·l, 

the device consumes only 8 W, including counting and data 

processing. It is therefore suitable for battery operation, and it 

has been used together with a solar panel for continuous 

aerosol measurements in the Swiss Alps at heights up to 4450 

m ASL [Baltensperger et al., 1990]. 

Figure 2 shows the first epiphaniometer data from MLO for 

December 1989. With the chosen time resolution of 30 min 

the lowest values found for this period are 2 orders of 

magnitude above the detection limit. Preliminary compariS-Ons 

show very good agreement with CNC and nephelometer data. 

On several days the usual pattern of diurnal variation caused 

by up-slope winds can be seen. 

Aclcnowledg~nt. We thanlc E. Robinson and A. Yoshinaga for their 

cooperation and surveillance of the epiphaniometer. Parts of this 

work were supported by the Swiss National Science Foundation. 

REFERENCES 

Baltensperger, U., H.W. Gaggeler, D.T. Jost, M. Emmenegger, and 

W. Nageli, Continuous background aerosol monitoring with the 

epiphaniometer, Atmos. Environ., 24A, in preu, 1990. 

Fuchs, N.A., Mechanics of Aerosols, Pergamon, New York, 1964. 

Gaggeler, H.W., U. Baltcnspergcr, M. F.mmcncggcr, D.T. Jost, A. 

Schmidt-Ott, P. Haller, and M. Hofmann, The epiphaniometer, a 

new device for continuous aerosol monitoring, J. Aerosol Sci., 20, 

557-564, 1989. 

Seinfeld, J.H., Atmospheric Chemistry alld Plrysic1 of Air PollwJiOll, 

John Wiley, New York, 1986. 

84 
Antarctic Ultraviolet Spectroradiometer Monitoring Program 

CHARLES R. BOOTH, Tnvi LUCAS, JONA TIIAN YEH, AND DA YID NEUSCHULER 

Biospherical Instruments Inc., San Diego, California 92117 

1. INTRODUCTION 

The establishment of a monitoring network for UV radiation 

has been a critical part of the U.S. Antarctic Program. Its 

purpose is to evaluate the consequences of stratospheric ozone 

depletion on the health and productivity of Antarctic organisms 

and personnel. Monitoring network sites are listed in Table 1. 

This network has collected data showing strong correlations 

between ozone depletion and elevated levels of shortwavelength UV irradiance. 

2. METIIODOLOGY 

The spectroradiometer system, manufactured by Biospherical 

Instruments, is designed for permanent mounting in a staffed 

facility and for continuous operation. The system is automatic, 

needing anention only for data transfer and periodic inspection. 

The instrument has wavelength and intensity calibration lamps 

for automatic calibrations at programmed intervals. An 

IBM-compatible computer is used to control the system and log 

the data. 

The double monochromator is the heart of the system which 

is configured with 167-μm input/output slits and a 250 μm 

intermediate slit. The throughput is f/3.5, and the focal length is 

0.1 m. The holographic grating is blazed for 1200 grooves m.m·1 

at 250 run. It can resolve spectral features that are approximately 0.5 run wide. The wavelength of interest is selected by 

changing the angle of the two tandem diffraction gratings 

relative to the input, output, and intermediate slits. The gratings 

are remotely turned with a computer-controlled stepping motor. 

The photomultiplier tube is a 28-mm-diameter 11-stage device 

with a bialkali cathode and a quartz window. Temperatures of 

the monochromator and photomultiplier are carefully controlled. 

Automatically actuated calibration sources (tungsten lamp and 

mercury discharge lamps) perform several calibration checks 

each day. The system is periodically calibrated using an optical 

standard traceable to NIST. 

3. RESULTS 

The amount of short wavelength UV radiation incident on the 

earth is governed by several factors, the most important being 

solar zenith angle, cloud cover, and atmospheric ozone 

concentration. Although 1988 and 1989 both showed considerable depletion of the ozone layer over Antarctica, the geographical distribution of the ozone "hole" as a function of time was 

different. A dramatic effect of the ozone depletion is seen in 

Figure 1. Here we compare spectral scans recorded at 

McMurdo at the same time on October 20 in 1988 and 1989. In 

1988, the TOMS satellite (A. Krueger, NASA Goddard 

Spaceflight Center, Greenbelt, Maryland, private communication, 1989) reported total column ozone concentration of 386 

DU, a relatively high level; 1 year later the concentration was 

161 DU, showing considerable ozone depletion. 

Most of the concern over ozone depletion has arisen because 

of the prediction that this would have significant biological 

impact. The spectral expression of this impact is commonly 

called the dose weighting or action spectra weighting. Figure 2 

shows the product of the irradiance spectra shown in Figure 1 

and the DNA damage action spectra determined by Setlow 

[1974]. This dosage increases dramatically at wavelengths 

shorter than about 310 run. The total dosage that an organism 

with this spectral susceptibility would receive is the integral of 

the area under the curves shown in Figure 2. The integrated 

doses from Figure 2, along with other spectral integrals and 

integrated biological doses, are given in Table 2. The effect of 

the enhanced UVB, reaching several thousand percent below 

303 run, is dramatic. It is interesting to note, also, that the effect 

of UVB, when defined as being 290-315 nm. is nearly twice that 

compared with the more popularly defined UVB of 290-320 run. 

TABLE 1. UV Monitoring Sites 

Site 

McMurdo 

Palmer 

Souih Pole 

Ushuaia, Argentina 

Barrow, Alaska 

La Jolla, California 

Longi1ude, 

deg. 

166.40E 

64.03W 

0 

68.00W 

156.78W 

117.3W 

Latitude, 

deg. 

77.SlS 

64.46S 

90.00S 

54.59S 

71.30N 

32.13N 

•CADIC: Centro Austral de lnvestigaciones Cien1ificas, Argentina 

85 

Established 

March 1988 

May 1988 

February 1988 

November 1988 

Fall 1990 

1991 

Location 

Arrival heights 

Clean air building 

Oear air building 

CA DIC• 
100 

10 

'e 

c 

N 

g 0.1 

~ ::!. 0.01 

0.001 

0.0001 

290 295 300 305 310 315 320 32S 330 335 340 

Wavelength (run) 

Fig. I. Log plot of irradiance (J!W cm·2 nm·1) recorded at 0100 UT on October 20, in 1988 (solid boxes) and 1989 (hollow boxes). TOMS-reported 

total column ozone was 386 DU (Dobson Units) in 1988 and 161DUin1989. 

0.01 

0.001 

·e 

c 

N 

'g 0.0001 

~ ::!. 

0.00001 

290 295 300 305 310 315 320 32S 340 Wavelength (run) 

Fig. 2. Log plot of dose weighted irradiance (J!W cm·2 nm·l) recorded al 0100 UT on October 20, in 1988 (solid boxes) and 1989 (hollow boxes). 

Setlow's DNA action spectrum [Set/ow, 1974] weighting was used. 

TABLE 2. Comparisons of24-h Averaged High Resolution 

Spectral lrradiance Recorded During October 20 in 1988 

and 1989, and of Computed Biological Doses 

1988 1989 % Difference 

/rradiance, μW cm·2 

UVB (290-315 nm) 3.53 14.74 +317% 

UVB (290-320 nm) 11.61 31.77 +174% 

298-303 nm 0.006 0.213 +3439 

UV A (320-400 nm) 602 786 +31% 

Visible (400-600 nm) 2892 3811 +32% 

Biological Dose, μW cm·2 

Skin [Diffey, 1987] 0.84 2.56 +206% 

DNA [Set/ow, 1974] 0.003 0.023 +638% 

Fish [Hunter, 1979] 0.02 0.074 +267% 

TOMS ozone concentrations were 386 DU in 1988 and 161 DU in 

1989, a difference of -58%. 

86 

Even with ozone highly depleted, the low sun angle at 

McMurdo on October 20 does not allow significant measurements of irradiance to be made below 290 nm. 

For wavelengths shorter than 290 run in the UVB portion of 

the spectrum, the effects of atmospheric ozone concentration on 

irradiance levels predominate the effects of cloud density. 

Figure 3 examines the period approaching October 20, 1989, as 

recorded by the spectroradiometer at McMurdo. During this 

period the total column ozone ranged from a maximum of 255 

DU to a minimum of 161 DU, nearly a record low for 

McMurdo. The mid-UV irradiance (shown at 350 run in Figure 

4) varied only slightly during this period, possibly due to 

varying cloud densities; the shorter UV irradiance (at 300 nm 

Figure 3) is much more variable, and shows a strong correlation 

with ozone concentrations reported by the TOMS satellite. The 

high-frequency variability exhibited at fringe areas of the ozone 

hole presents challenges in assessing the effects of ozone 

depletion on living organisms. It also suggests that a profound 

biological impact might occur if a stationary region of ozone 

depletion were to occur over a region of high biological activity. 
0.1 

0.09 

o.oa 

0.07 

0.06 

0.05 

0.04 

0.03 

0.02 

0.01 

300 

250 

200 

150 

100 

50 

0 

10/14/89 10/ 15/ 89 10/18/ 89 10/ 17 /89 10/18/89 10/19/ 89 10/ '20/89 10/ 21 / 89 

0 

10/22/ 89 

Fig. 3. Time series of irradiance and total orone recorded at McMurdo station during passage over the station of an ozone-depleted region. The 

downtrending line with the solid boxes is the total column orone (DU, right scale) reported by the TOMS satellite. The hollow boxes denote the 

irradiance (μW cm·2 nm·1, left scale) at 300 nm. Solar zenith angle during the time of the measurements ranged from 66' to 92'. 

25 300 

250 

200 

15 

150 

10 

100 

5 50 

10/ 15/89 10/18/89 10/17/89 10/18/89 10/ 19/89 10/ '20/89 10/ 21/89 

0 

10/22/89 

Fig. 4. Time aeries of mid-UV (350 nm) irradiance and total ozone recorded at McMurdo during passage over the station of an ozone-depicted region. 

Tiie downtrcnding line with the solid boxes is the total column ozone (DU, right scale) reported by the TOMS sateUite. Tiie hoUow boxes denote the 

irradiance (μW cm·2 nm·l, left scale). Solar zenith angle during the time of the measurements ranged from 66' to 92'. 

4. SUMMARY 

The establislunent of a monitoring network for UV radiation 

has been a critical part of the U.S. Antarctic Program. Its 

purpose is to evaluate the consequences of stratospheric ozone 

depletion on the health and productivity of Antarctic organisms 

and personnel. This monitoring network supports scientific 

researchers in Antarctica, and has provided independent 

confirmation of the role of the ozone layer in moderating UV 

solar irradiance. 

Aclutowltdg~nl. This research and monitoring activity was funded by 

contract A9H074 to Biospherical Instruments from ITf Antarctic 

Services, Inc., and AOT-000010 from Antarctic Support Associates 

under direction of NSF, Division of Polar Programs. Data from the NSF 

87 

UV Spectroradiometer Net work is available to aU qualified researchers. 

NSF grantees have priority access to these data. For more information, 

contact Dr. Polly Penhale, Division of Polar Programs, National Science 

Foundation, 1800 G St. N.W., Washington, D.C. 20550. 

5. REFERENCES 

Diffey, B L., A comparison of dosimeters used for solar ultraviolet 

radiometry, Photochem. Photobio., 46, 55-60, 1987. 

Hunter, J. H., J. H. Taylor, and H. G. Moser, The effect of untraviolet 

irradiation on eggs and larvae of the northern anchovy, Engraulis 

mordax, and the pacific mackerel, Scomber japonicus, during the 

embryonic stage, Photochem. Photobicl., 29, 325-338, 1979. 

Setlow, R. B., The wavelengths in sunlight effective in producing skin 

cancer: A theoretical analysis, Proc. NaJ . Acad. Sci. U.S.A., 71(9), 

3363-3366, 1974. 
Chemical Resolution of Fine Aerosol Mass at MLO: The Role of Organic Matter 

T. A. CAHILL, L. K. WILKINSOJ-f, AND R. A. ELDRED 

University of California, Davis, Crocker Nuclear Laboratory, Air Quality Group, Davis, California 95616 

1. INTRODUCTION 

On March 2,1988, the U.S. remote-area fine particulate 

network (IMPROVE) [Eldred et al., 1989) initiated routine 

monitoring of fine (DP < 2.5 μm) 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 the Hawaii Volcanoes National 

Park (HA VO). 

The protocols for MLO call for a continuous sample of 

approximately 3 days duration (MALOl) and a clean-air 

(downslope only) sample over the same 3-day period 

selected by the Maryland System (MAL02) (Zoller et al., 

personal communication). Size segregation is accomplished 

through a nominally 2.5-μm cyclone (modified by altitude), 

and samples are collected on 25-mm stretched Teflon filters. 

Samples are mailed weekly to Davis, California.where 

analyses are done for (1) mass (gravimetric); (2) elemental 

content, Na to U (PIXE); (3) hydrogen (PESA); and (4) H, 

Be, B, C, N, 0, and Na (FAST) [Cahill et al., 1984]. With 

the availability of organic matter from the hydrogen content 

of the filters by means of PESA, we can now attempt a 

resolution of fine mass into all its chemical components. 

2. RECONSTRUCTION OF FINE MASS 

Figure 1 shows a comparison between the reconstruction 

of fine mass (sum of chemical species) to the fine mass 

measured by weighing the filters for the period March 

1-November 30, 1989. The sample chosen was for 

downslope winds only (MAL02) March 1-November 30, 

1989, but a similar result is available for the averaged 

sample (MALO!). The value of r2 (0.96) and the intercept (1 

ng m·3) show that all measurements are precise and that 

systematic offset is negligible. The slope (0.84) shows that 

84% of the weighted mass is recovered by this reconstruction. There are several possible reasons why this value is 

less than 100%. Most chemical species are measured in a 

vacuum, so volatiles such as water are driven from the 

sample. Further, the exact chemical state of the sulfur is 

uncertain. We normally assume ammonium sulfate at other 

remote U.S. sites, but that is not at all certain at MLO. Since 

across the United States we normally recover 93% of the 

gravimetric mass by this procedure, we suspect that the 

sulfates include a component of sulfuric acid and/or 

ammonium bisulfate, which would tend to raise the 

reconstructed mass above 90%. Finally, some components 

such as chlorides and nitrates are not incorporated into the 

reconstruction mass. 

88 

4000 . 

........ 

t') 

* * 2 

'-... 

Ill 

E 

0 

'--

0' 

0 

c 

0 

c 

<( 

2 

u 

a::: 

0. 

... 

0. MF (nanograms/M .. 3) 4000. 

Fig. I. Reconstructed fine mass (RCMA) versus measured fine 

mass (MF) for MLO, March I-November 30, 1989, in downslope 

winds (MAL02). The slope is 0.84; r

2 = 0.96. 

3. COMPARISON OF DATA FROM MLO AND HAVO 

Further information may be gained by comparing the 

MLO data with similar data from the HA VO IMPROVE site 

near the Visitor Center, at an elevation of 1.25 km MSL 

(Table 1). At this site, nitrates and chlorides are also 

measured, and reconstructed mass closely matches weighted 

mass. If we assume that nitrates fall off from HA VO to 

MLO in proportion to the sulfates, and assume that chlorides 

in smoke from agricultural burning fall off in the same ratio, 

MLO reconstructed mass closely approximates the gravimetric mass also. However, this agreement cannot be taken 

too seriously because of uncertainties in the carbon soot 

conversion and the extrapolations. 

Nevertheless, the comparison data are quite revealing in 

many areas. The importance of organic matter in downslope 

winds (MAL02) is somewhat surprising, considering the 

presumed strong organic-matter sources in Hawaiian 

vegetation, agricultural burning, and petroleum use. Yet, 

this does not appear to be the case for fine aerosols. We do 

not believe this is a measurement error, since the IMPROVE 

protocols call for two independent measurements of organic 

matter, one by combustion from quartz filters, and one by 

hydrogen from Teflon filters. The excellent agreement 

obtained for over 1300 samples by two different techniques 

(and two different laboratories) makes us confident that no 

major error exists in the MAL02 data [Cahill et al., 1990]. 

4. COMPARISON OF AVERAGE TO DOWNSLOPE 

WIND SAMPLES AT MLO 

To understand the relatively elevated organic matter 

present in the downslope-wind (MAL02) samples, we can 
TAB LE 1. Comparison of Aerosols 

Parameter Measured 

HAVO, 

ng m·3 

MALO! 

(Average), 

ng m·3 

MLO 

MAL02 

(Downwind Only), 

ng m·3 

Coarse Aerosols (DP< 10 μ.m) 

Mass 14,501 NA NA 

Fine Aerosols (DP< 2.5 μ.m) 

Mass (gravimetric) 1825 1107 893 

Major Species 

Sulfates [as (NH4)iS04] 

Chlorides• 

Organic matter (II) 

Nitrates (as N114!'\03) 

Soils 

Soot carbon (?)t 

870 

312 

129 

98 

93 

190 

1692 

629 

130 

86 

71 

105 

165 

lT86 

430 

(El) 99 (El) 

149 

(E2) 48 (E2) 

82 

99 

907 

Tracer Species 

Nonsoil potassium (smoke) 

Vanadium 

Nickel 

Copper 

Zinc 

Arsenic 

Selenium 

Bromine 

Lead 

9.1 

0.6 

0.4 

0.6 

1.7 

0.2; 

0.3; 

0.8 

1.0 

EI = Extrapolated based on non soil potassium, since sea-level source. 

E2 = Extrapolated based on sulfates. 

•As NaCl-496 ng m-3. 

3.8 2.9 

0.2 0.4; 

0.1 0.2 

0.2 0.4 

0.6 0.6 

<0.1 <0.1 

<0.1 <0.1 

0.3 0.4 

0.4 0.5 

tConversion from optical absorption to soot carbon mass estimated-no local calibration. 

tLess than 30% of values above minimum detectable limit. 

examine the other major components, namely, sulfur 

(sulfates) and organic matter, shown in Figures 2 and 3. 

Although the patterns are clearly uncorrelated, more 

information can be gained by examining sulfur in average 

(MALOl) and downslope-wind samples, shown in Figure 4. 

Sulfur in the average samples is always greater than or equal 

to sulfur in the downslope-wind samples, very much like 

gravimetric mass. This is not the case for organic matter 

(Figure 5), which shows both poor correlation between 

MALOl and MAL02 samples, and numerous times when 

organics in downslope winds were higher than averaged 

values, in agreement with data in Table 1. Thus, it is not 

surprising that organic matter and sulfur are essentially 

uncorrelated (Figure 6), having rl = 0.17. 

What does correlate with organic matter in downslope 

wind samples? The two components that correlate best are 

both tracers of smoke: optical absorption, expressed as soot 

carbon (Figure 7), and nonsoil potassium, which is typically 

5 to 8% of smoke mass (Figure 8). Thus, the conclusion 

must be that most of the organic matter is due to smoke, 

despite the fact that it occurs in downslope winds. The 

evidence 'of sulfur, however, hints that the smoke organics 

are not Hawaiian, or they too would follow the pattern of 

Figure 4. Further support for this hypothesis is provided by 

the observation that organic matter peaks during periods of 

dust transport from Asian sources [Cahill et al., 1989). 

There exists, however, an organic component not 

associated with smoke, as shown by the nonzero intercept of 

both graphs. From 50 ng m·3 (absorption intercept) to 100 

ng m·l (nonsoil potassium intercept) of the organic matter is 

not smoke related, the non-smoke-related organic matter 

being as large as 270 ng ml on some days. 

5. CONCLUSIO'.'< 

In conclusion, a reasonable reconstruction of fine 

gravimetric mass has been made at MLO for both daily 

average conditions and downslope-wind conditions. Fine 

89 
~ 

... 

""' 

e 

c. 

.=. 

"" 

'"° 

OJ/ 01 /9? 11/ J0/ 8rt FINE STAGE (< 2.5μ) 

Fig 2. Fine particulate sulfur at MLO in downslope winds 

(MAL02). Some data are missing, October 1989. 

"" 

... 

.'00 

i 

g' 

; i"o) 

... ' 

II 11 11 111 1

1

' 11 11 

(1 .1/01 / 89 11 / lfl/ AO FINE STAGE(< 2.5μ) 

Fig. 3. Fine particulate organic mass from hydrogen at MLO in 

downslope winds (MAL02). Some data are missing, October 1989. 

550. 

,,....._, 

n 

* * :::2 

"'-.. 

l/l 

E 

0 

L 

(JI 

0 

c 

0 

c 

(/) 

0. 

.). 

/ 

o. s 

/ 

/ 

1 • . 

/ 

/ 

/' 

/ 

• / 

(nanogrnms/M**3) 

/ 

550. 

Fig. 4. Fine particulate sulfur, MALO! (x-axis), versus MAL02 

(y-axis), March I-November 30, 1989. The averaged values 

(MALO!) are always greater than or equal to values ii:i downslope 

winds (MAL02) as indicated by the dashed line in the figure. 

90 

550. ,.....,. 

n 

* * :::2 

"'-.. 

Ill 

E 

0 

L 

O' 

0 

c 

0 

c ....__, 

I 

~ ~1 

0. 

0. OMH (na nogroms/ M**3) 550. 

Fig. 5. Fine particulate organic matter, MALO! (x-axis), versus 

MAL02 (y-axis), March I-November 30, 1989. Compare with 

Figure 4. 

550. ,,....._, 

t") 

* * 2 

"'-.. 

l/l 

E 

~ 

01 

0 

c 

0 

c 

I 

:::::!' 

. 

.. 

.. 

. 

. ·' 

0 .o f----l--+----l- -+---+--+---+- +---+__J 

0. s (na nograms/M**3 ) 550. 

Fig. 6. Fine particulate sulfur versus organic matter at MAL02, 

March I-November 30, 1989. Note the lack of correlation; r2 = 0.17. 

500. ,.....,. 

n 

* * :::::!' 

' l/l 

E 

0 

L 

O' 

0 

c 

0 

c ....__, 

~ 

_J 

0. 

0. 

.. •. . . . 

OMH 

550. (nonograms/Mu3) 

Fig. 7. Optical absorption (LR) versus fine particulate organic 

matter (OMH) at MAL02, March I-November 30, 1989. The 

correlation r2 = 0.64; the slope is 1.02. 
80. ,........ 

10 

* 

~ * 

" Cl) 

E 

0 

..... 

Ol 

0 

c 

0 

c ...__,, 

z 

0 

z 

::.:: 

0. .. 0. OMH 

.. 

. (nonogroms/M**3) 550. 

Fig. 8. Excess fine potassium (KNON), a smoke tracer, versus 

organic matter (OMH) at MAL02, March I-November 30, 1989. 

The correlation r2 = 0.60. 

aerosol mass at MLO at 3.47 km averages about 60% of that 

at the HA VO Visitor Center at 1.25 km, while the downslope 

component averages about 50% of that of the HA VO site. 

One might expect much lower values at MLO, but this is not 

91 

the case. Even more surpnsmg is that organic matter is 

greater in MLO downslope winds than at HA VO. We have 

tentatively separated the organic matter into a smoke-related 

component (-60% of organic mass) and a non-smoke-related 

component (-40% of organic mass). With the availability of 

a full year's data, further studies are planned to examine the 

two components relative to meteorological conditions, with 

the goal of confirming the Asian source of organic matter. 

6. REFERENCES 

Cahill, T.A., R.A. Eldred, D. Shadoan, P.J. Feeney, B.H. Kusko, and 

T. Matsuda, Complete elemental analysis of aerosols: PIXE, 

FAST, LIPM, and mass, Nuc/. /nstrum. Meth., BJ, 291-295, 

1984. 

Cahill, T.A., L.K. Wilkinson, P. Beveridgr,, and T. Tanada, Fine 

particulate matter at Mauna Loa Observatory March 1988 to 

February 1989, in Geophysical Monitoring for Climatic Change, 

No. 17: Summary Report 1988, edited by J.W. Elkins and R.M. 

Rosson, pp. 82-84, NOAA Air Resources Laboratory, Boulder, 

CO, 1989. 

Cahill, T.A., R.A. Eldred, L.K. Wilkinson, and B.P. Perley, Spatial 

and temporal trends of fine particles at remote U.S. sites, Paper 

90-66.4 presented at the 83rd Annual Meeting and Exhibition, 

Air and Waste Management Association, Pittsburgh, PA, June 

24-29, 1990. 

Eldred, R.A .. T.A. Cahill, L.K. Wilkinson, P.J Feeney, and W. 

M&lm, Particulate characterization at remote sites across the 

U.S.: First-year results of the NPS/IMPROVE Network, 

Proceedings of Annual Meeting, Air and Waste Management 

Association, Anaheim, CA, paper 89-151.3, 1989. 
Artificial Windshielding of Precipitation Gauges in the Arctic 

GEORGE P. CLAGETT 

Soil Conversation Service, Anchorage, Alaska 99501 

1. INTRODUCTION 

Precipitation gauges can provide good measurements of 

the water equivalent of snow precipitation, provided the 

gauge is protected or shielded from wind effects. Unfortunately, there are no standards for collecting snow 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 ~tudies of artificial shields in the United 

States and Canada have produced a wide range of results. 

This must be, in part, due to the wide range of weather 

conditions under which the various studies have been 

conducted. A lingering problem is applying the results to the 

local conditions of Alaska's tundra regions. 

2. METHODS 

A study of the windshield alternatives, under the unique 

conditions of Alaska's Arctic coastal region, was set up at 

the CMDL facility at BRW during September 1989. 

Snowfall catches from four newly installed prel:ipitation 

storage gauges were compared with that from an existing 

storage gauge protected by a Wyoming shield [Hanson, 

1988). Two of the new gauges were shielded-one with a 

Nipher shield [Goodison et al., 1983] and the other with an 

Alter shield [Alter, 1937}--and two were unshielded. One 

of the unshielded gauges was serviced on an event basis, the 

same as the three shielded gauges. The other unshielded 

gauge was treated as if it were a remote gauge, allowing rime 

to build up and dissipate naturally to see what effects rime 

had on the overall catch. The four newly installed gauges 

are 20.3 cm in diameter x 100 cm tall, mounted with the 

orifice 2 m above the normal ground surface. The existing 

Wyoming-shielded gauge is 30.5 cm in diameter x 2 m tall, 

and is equipped with a Leupold-Stevens water-level recorder. 

3. RESULTS 

Provisional results from the 1989-1990 winter season 

indicate that the Wyoming-shielded gauge provided slightly 

more than 6.0 cm of snowfall water-equivalent catch. The 

Nipher-shielded gauge caught 3.9 cm of water-equivalent 

precipitation, or only 64% of that of the Wyoming-shield 

gauge. The Alter-shielded gauge caught 2.9 cm, or slightly 

less than half that caught by the the Wyoming-shielded 

gauge. The unshielded but serviced gauge caught only 1.7 

cm of water-equivalent snowfall which was less than 28% of 

that of the Wyoming-shielded gauge. The unshielded and 

-ion-serviced gauge caught the least amount of snowfall, only 

1.1 cm water equivalent, or 17% of the snowfall caught by 

the Wyoming-shielded gauge. 

These results are generally what was expected with one 

exception: the Nipher-shielded gauge was expected to catch 

as much snow as did the Wyoming-shielded gauge. The 

results otherwise confirm that the unshielded and Altershielded gauges do not catch adequate amounts of 

precipitation at exposed and windy locations during 

snowfall events. 

Aclcnowledg~nt. Appreciation is expressed to D. Endres, Station 

Chief, BRW, who serviced the precipitation gauges and collected 

the snow samples. 

4. REFERENCES 

Alter, :;.c., Shield storage prec1p1tation gauges, Mon. Weather 

Rev., 65, 262-265, 1937. 

Goodison, B.E., V.R. Turner, and J.E. Metcalfe, A nipher-type 

shield for recording precipitation gauges, Proceedings, 5th 

Symposium on Meteorological Observatio11.t and !11.ttrununtation, Toronto, Ontario, Canada, pp. 2-126, American 

Meterological Society, Boston, 1983. 

Hanson, C.L., Precipitation measured by gages protected by the 

Wyoming shield and the dual-gauge sytem, ProcudingJ, 56th 

Western Snow Conference, Kalispell, Montana, pp. 174-177, 

Colorado State University, Fort Collins, 1988. 

92 
UVB Monitoring Data from Rockville, Maryland . . 

DA YID L. CORRELL, CARL CLARK, R USSELL GOODRICH, AND DOUGLASS HA YES 

Smithsonian Environmental Research Center, P.O. Box 28, Edgewater, Maryland 21037 

Our laboratory has been 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' highprecision, accurately calibrated, interference-filter spectral 

radiometers. Significant data sets have been collected at 

BRW (71 'N); Rockville and Edgewater, Maryland (39'N); 

Tallahassee, Florida (30'N); MLO (19' N); Republic of 

Panama (9'N); and SPO (90'S). Long-term data sets are now 

being edited and analyzed for publication and archiving; 

these sets include data from 1976 to the present at Rockville 

and from August 1984 to the present 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 sunset, and effects of cloud cover; and correcting 

for calibration changes, malfunctioning equipment, and 

altered equipment design. 

Rockville data from 1976 through 1989 have now been 

edited and are archived on 9-track computer tapes. These 

data are available in archived format on floppy discs with a 

de-archiving manual and software, for $100. Extensive 

analyses of these data are in progress, and a few highlights 

are reported here. Requests for data and additional information should be directed to David L. Correll, Director, at the 

above address. 

A new-generation, 18-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 modern electronics, 

but also improved PC-based data acqumllon and 

microprocessor-controlled choices of set gains over 3 orders 

of magnitude for different channels in the same operational 

instrument. Both the present radiometers and the 

radiometers under development operate as cosine light 

collectors to measure global irradiance. We are currently 

surveying possible additional station sites in order to attain 

an optimal range of latitudes for future data collection. 

Dobson spectrophotometer ozone data from Wallops 

Island, Virginia (Figure 1), were used to drive the Green 

model [Runde/, 1986; Green, 1983; Green et al., 1980; 

Schippnick and Green, 1982] for calculations of predicted 

UVB flux incident on Earth at 39'N latitude under clear-sky 

conditions and at a fixed solar secant. These predictions 

were then compared with actual data from Rockville under 

those conditions (Figures 2-4). In these comparisons we 

used the effective center wavelength for the appropriate 

spectra radiometer channel. These effective center 

wavelengths were obtained by convoluting the appropriate 

interference filter and blocking filter transmission curves, 

detector spectral response curves, and calibration lamp and 

global irradiance spectral curves. In Figure 2, 305-nm 

monitoring data at a morning solar secant of 2.5 for clear-sky 

days are compared with Green model predictions. The 

results are generally close. In Figures 3 and 4, monitoring 

data for 305 and 320 nm, respectively, at morning secants of 

1.5 under clear-sky conditions are compared with Green 

model predictions. For 305-nm data, the comparisons are 

close, although a secular variation is evident in the observational data for which we currently have no satisfactory 

explanation. For the 320-nm data, the model predictions are 

consistently about 10-20% higher than the monitoring data. 

This is probably due to the effects of atmospheric gases such 

as S02, and to aerosols, whose effects are not included in the 

model calculations. Certainly the changes in global 

irradiance we are reporting are not due to significant changes 

in UVB radiation incident on the earth's atmosphere [Lean, 

1989). 

0.7,-------- -----------, 

0.65 

0 .6 

~ 0.55 

~ ::;; 0.5 

2. 0.45 w 

z 0.4 

~ 0.35 

0.3 

0.25 

0.2 - - ---. Mar-71 Dec-73 Aug-76 May-lS ~·62 Nov·64 Aug·67 May-90 

DATE 

V DATA - SMOOTHING = 0.2- SMOOTHING =4 

Fig. I. Dobson spectrophotometer ozone data from the Wallops 

Island station, used as inputs to the Green model. 

c 

~ E 

-E 

:::!E 

O' 

"' ::i 

~ (/) 

z 

w 

~ 

0.8 

0.7 ROCKVILLE DATA 

0.6 

GREEN MODEL 

0.5 

0.4 I 

0.3 

0.2 

0.1 

• • • . 

• 

• 

0-1----.----.---- .----......---.----.------1 

May·79 Oct-60 Feb·62 Jul-63 Nov·64 Mar-66 Aug·87 Dec·66 

DATE 

Fig. 2. Comparison of Green model predictions with Rockville, 

Maryland (30'N), UVB fluxes at 305 nm on clear days al a solar 

secant of 2.5. 

93 
c 

.€ 

E 

.!:;. 

~ 

.[ 

::2. 

~ (fl 

z 

w 

~ 

3 

a a 

25 CCl a ROCKVILLE DATA 

80 

2 

1.5 a 

0.5 ~11 a 

-1--~~----.-~~ ..--~~----.-~~~..--~~-'i<i'-~---1 

Sep-75 May-78 Feb-81 Nov-83 Aug-86 May-89 Feb-92 

DATE 

Fig. 3. Comparison of Green model predictions with Rockville, 

Maryland (39.N), UVB fluxes at 305 nm on clear days at a solar 

secant of 1.5. 

REFERENCES 

Green, A.E.S., The penetration of ultraviolet radiation to the ground, 

Physiol. Plant, 58, 351-359, 1983. 

Green, A.E.S., KR. Cross, and L.A. Smith, Improved analytic 

characterization of ultraviolet skylight, Photochem. Photobiol., 31, 

59-65, 1980. 

Lean, J., Contribution of ultraviolet irradiance variations to 

c 

~ 

i 

! 

~ (/) 

z 

w 

~ 

16 

a 

14 

12 

10 

8 

6 

,,~~ilJ ,,, , f !"I -;,~ 0 

"'a a a ~ a ROCKVILLE DATA Cb 

4 

2 

GREEN MODEL 

O-r-~~----.-~~~..--~~----.-~~~..--~~-1'cP>-~--1 

Sep-75 May-78 Feb-81 Nov-83 Aug-86 May-89 Feb-92 

DATE 

Fig. 4. Comparison of Green model predictions with 

Rockville, Maryland (39.N), UVB fluxes at 320 nm on clear 

days at a solar secant of 1.5. 

changes in the sun's total irradiance, Science, 244, 197-200, 

1989. 

Runde!, R., Subroutine for Schippnick and Green model, in 

Slratospheric Ozone Reduction, Solar Ultraviolet Radiation and 

Plant Life, edited by R.C. Worrest and M.M. Caldwell, pp. 

361-364, Springer-Verlag, Berlin, 1986. 

Schippnick, P.F., and A.E.S. Green, Analytical characterization of 

spectral actinic flux and spectral irradiance in the middle 

Ultraviolet, Photochem. Photobiol., 35, 89-101, 1982. 

94 
Roberston-Berger UVB Meter 

GERALD F. COTTON 

NOAA, Air Rtsources Laboratory, Si/vu Spring, Maryland 20910 

1. INTRODUCTION 

MLO has served as one of the original 10 monitoring sites 

for the Roberson-Berger (R-B) sunburning meter network 

since its inception in 1974. An additional 35 sites, including 

11 non-U .S. sites, distributed unevenly worldwide, have 

operated with varying lengths of record. The period of 

record of the individual R-B observing sites is given in Table 

I. Until June 1989, the Skin and Cancer Hospital of Temple 

University has maintained the network, principally with 

contract support from the NIH, DOT, and EPA, and with 

extensive field support by NOAA 's ERL and NWS. Because 

the Skin and Cancer Hospital closed this year, the operation 

of the network is being reviewed to determine whether 

measurements should be continued to overlap with measurements by more sophisticated instrumentation. The National 

Cancer Institute of NIH retains the data archive along with 

ancillary meteorological information. 

I. 

2. 

3. 

4. 

5. 

6. 

7. 

8. 

9. 

10. 

11. 

12. 

13. 

14. 

15. 

16. 

17. 

18. 

19. 

20. 

21. 

22. 

23. 

24. 

25. 

I. 

2. 

3. 

4. 

5. 

6. 

7. 

8. 

9. 

10. 

11. 

TABLE 1. Robertson-Berger Meter Network Period of Record 

and Number of Complete Years of Data Through 1987 

Station Period of Record 

U.S. Stations 

Albuquerque, NM Jan. 1974-Present 

Atlanta/Emory, GA Oct. 1977-Sept. 1987 

Bismarck, ND Jan. 1974-Feb. 1987 

Burlington, VT Oct. 1985-Present 

Concord, NH Oct. 1985-Present 

Des Moines, IA Jan. 1974-Dec. 1987 

Detroit, MI Sept. 1977-Present 

El Paso, TX Jan. 1974-Prescnt 

Ft. Wonh, TX Jan. 1974-Present 

Gainesville, FL Jan. 1975-Aug. 1980 

Honeybrook, PA Jan. 1975-July 1985 

La Jolla, CA May 1979-Mar. 1983 

Lihue, HI Feb. 1987-Present 

Mauna Loa, HI Jan. 1974-Present 

Miami, FL May 1986-Present 

Minneapolis, MN Jan. 1974-Present 

New Orleans, LA Nov. 1977-Present 

Oakland/Redwood City, CA Jan. 1974-Present 

Philadelphia, PA Jan. 1974-Present 

Pt. Barrow, AK Oct. 1978-Present 

Rockville, MD Sept. 1978-July 1985 

Salt Lake City, UT Oct. 1977-Present 

Seat1Je, WA Oct. 1977-Present 

Tallahassee, FL Jan. 1974-May 1986 

Tucson, AZ Jan. 1980-Present 

Non-U.S. Stations 

Brisbane, Australia Oct. 1974-April 1981 

Melbourne, Australia Dec. 1974-Nov. 1986 

Hamburg, Germany Feb. 1976-June 1983 

Hamilton, New Zealand May 1980-Present 

Invercargill, !'i'ew Zealand Sept. 1981-0ct. 1985 

Barro Colorado, Panama Nov. 1978-Prescnt 

Belsk, Poland May 1975-Present 

Warsaw, Poland June 1975-Sept. 1976 

Norrkoping, Sweden Oct. 1982-Presenl 

Basel, Switzerland Mar. 1980-Present 

Davos, Switzerland Jan. 1975-Present 

95 

Years of Data 

12 

7 

11 

2 

2 

9 

10 

13 

14 

2 

JO 

3 

0 

12 

0 

13 

4 

12 

14 

8 

5 

9 

9 

12 

6 

7 

II 

5 

3 

2 

3 

II 

I 

4 

7 

13 
2. INSTRUMENTATION AND DATA 

The R-B meter was selected in the early 1970's as a 

UV-monitoring instrument at the surface for the Climatic 

Impact Assessment Program [CIAP, 1975] sponsored by the 

DOT in reaction to concerns about possible climate impacts 

by the projected supersonic air transportation 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 

1/lOOth that at 295-300 nm. Although the performance of 

the R-B meter has always been controversial, especially with 

respect to the wide UVB bandwidth and more recently with 

possible long-term instability (calibration drift) [Scotto et al., 

1988). it has proved to be a rugged, reliable instrument in the 

field. The Temple University staff maintained individual 

instrument calibrations, which were performed annually 

through 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 et al., 1975; Machta et al., 1976; Barton·, 1983; 

and Paltridge and Barton, 1978). In addition, DeLuisi and 

Harris [1983] performed an important, though limited, study 

of the meter behavior, providing estimates of the radiant 

energy of the somewhat arbitrary R-B sunburn units of 

measurement under certain conditions. Finally, there have 

been efforts 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 University. 

Data from these instruments are unavailable at this writing. 

The published results of the CSIRO Australian network 

(1975-1981) include both types of instrumentation [Barton, 

1983; Paltridge and Barton, 1978]. 

The data from the R-B observing sites are retained as 

half-hourly sunburn units, which are archived with daily and 

monthly · sunburn-unit totals and with observed daily and 

monthly Dobson spectrophotometer total ozone values, 

percent sunshine, total cloudiness, and broadband solar 

radiation amounts, where these are available. These data 

may be obtained from Joseph Scotto, National Cancer 

Institute, NIH, Public Health Service, Bethesda, MD 20892. 

3. REFERENCES 

Barton, I.I., The Australian UV-B monitoring network, Technical 

Paper No. 46, 12 pp., CSIRO, Division of Atmospheric Physics, 

Melbourne, Australia, 1983. 

Berger, D, The sunburning ultraviolet meter: Design and performance, Photoclum. Photobiol .. 24, 587, 1976. 

Berger, D., Product Brochure, Solar Light Co., Philadelphia, 

Pennsylvania, 1989. 

ClAP (Climate Impact Assessment Program), Impacts of climatic 

change on the biosphere, CIAP Monograph 5, Final Report, 

DOT-TST-75.55, Department of Transportation, Washington, 

DC, 1975. 

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

energy of a Robenson-Berger Meter sunburn unit, Almos 

Environ., 17(4), 751-538, 1983. 

Machta, L., G. Cotton, W. Hass, and W. Komhyr, Erythemal 

ultraviolet solar radiation and environmental factors, Proc. of tlu 

Fourth Conference on tlu Climatic Impact Assessment Program, 

DOT-TSC-OST-75-38, pp. 405-411, National Technical 

Information Service, Springfield, VA, 1976. 

Mo, T., A.T. Chai, and A.E.S. Green, An absolute calibration of the 

sunburn meter, CIAP Monograph 5, Appusdu L, Department of 

Transportation, Washington, DC, 1975. 

Paltridge, G.W., and I.I. Barton, Erythemal utraviolet radiation 

distribution over Australia: Calculation, detailed results, and 

input data, Technical Paper No. 33, 48 pp., CSIRO, Division of 

Atmospheric Physics, Melbourne, Australia, 1978. 

Scotto, ]., G. Cotton, F. Urbach, D. Berger, and T. Fears, Biologically effective ultraviolet radiation : Surface measurements in the 

United States, 1974-1985, Science, 239, 762-764, 1988. 

96 
The CSIRO Latitudinal Gradient Study: Methane Data from Air Samples 

Collected at CMDL Baseline Observatories and at Cape Grim, Tasmania 

PAUL FRASER, PAUL STEELE, ROGER FRANCEY, AND GRAEME PEARMAN 

CS/RO, Division of Atmospheric Research, Aspe!lda/e, Victoria, Australia 3195 

1. INTRODUCTION 

In 1983 the CSIRO Division of Atmospheric Research, 

with the logistical support of NOAA/CMDL, commenced 

flask sampling of air at the four CMDL baseline atmospheric 

observatories. The principal purpose of this sampling 

program is to measure the isotopic composition (13C and 180) 

of atmospheric col. and to assess seasonal and geographic 

variations in these species [Francey et al., 1989). In 

addition to the isotopic analyses of C01, the 5-L flask 

samples are also analyzed at CSIRO for CH4, CO, and C01, 

by the method of gas chromatography, using a flame 

ionization detector [Fraser, 1984; Fraser et al., 1986; P. J. 

Fraser et al., Methane in the southern troposphere: Observations and analysis, in preparation, 1990). In this report we 

present the CSIRO CH4 data from the 5-L flask samples, 

together with the CSIRO record of atmospheric CH4 

measured at Cape Grim, Tasmania, for 1984-1988. We 

compare these data with the CH4 mixing ratios obtained by 

the CMDL program through flask sampling at the same five 

sites [Steele at al., 1987; Lang et al., 1990a, b). 

2. DATA 

The CSIRO monthly mean CH4 data from the CMDL 

observatory sites and from Cape Grim are given in Tables 

1-5. These CSIRO data are shown in Figure l, with monthly 

average data obtained by CMDL at the same sites from air 

samples collected in 0.5-L glass flasks [Steele et al., 1987; 

Lang et al., 1990a ,b). The CSIRO data are referenced to a 

calibration scale that was derived from several calibrated 

natural air standards supplied by OGIST (formerly OGC) 

[Rasmussen and Khalil, 1981; Fraser et al., 1986). In a 

similar fashion, the CMDL data are referenced to a calibration scale based on two tanks of calibrated natural air 

purchased from OGIST in 1983-1984 [Lang et al., 1990a]. 

3. DISCUSSION 

Inspection of Figure 1 reveals a striking level of agreement between the two data sets. For each month at each site 

we calculated, when possible, the ratio of the CMDL value 

to the CSIRO value. The average values of these ratios for 

each site are shown in Table 6. At all sites these average 

ratios are not significantly different from unity (Table 6). 

There are noticeable differences between the two programs 

for specific months at BRW, MLO, and SMO. Almost 

certainly these are due to the lower sampling frequency in 

the CSIRO program; a representative monthly mean mixing 

ratio is not always captured. 

TABLE 1. Monthly Mean CH4 Data (ppbv) From 5-L 

Glass Flask Samples Collected at BRW During 

1984-1988 and Analyzed at CSIRO 

Month 1984 1985 1986 1987 1988 

Jan. 1725 1749 1766 1786 

Feb. 1742 

March 1718 1743 1796 

April 1738 1778 1753 

May 1703 1727 1744 1751 1752 

June 1702 1708 1730 1738 

July 1739 1755 

Aug. 1706 1722 1711 1728 1736 

Sept. 1705 1745 

Oct. 1715 1775 1777 

Nov. 1725 1774 1811 

Dec. 1760 1767 1779 

Annual Mean 1720 1734 1748 1761 1765 

The average number of flasks filled per month is two. 

TABLE 2. Monthly Mean CH4 Data (ppbv) From 5-L 

Glass Flask Samples Collected at MLO During 

1984-1988 and Analyzed at CSIRO 

Month 1984 1985 1986 1987 1988 

Jan 1649 1671 1670 

Feb. 1658 1642 1676 1687 

March 1630 1664 1658 1696 

April 1639 1653 1672 1669 

May 1617 1659 1650 1674 

June 1627 1651 1637 1680 1676 

July 1618 1647 1667 1675 

Aug. 1622 1628 1663 1651 1689 

Sept. 1652 1631 1632 1653 1692 

Oct. 1640 1672 1691 1697 1668 

Nov. 1636 1665 1663 1679 

Dec. 1638 1662 1669 1661 1725 

Annual Mean 1634 1652 1661 1669 1687 

The average number of flasks filled per month is two. 

The results shown in Table 6 indicate that, in an average 

sense, there is very good agreement between the CMDL and 

CSIRO measurements of atmospheric CH4 • It is notable that 

the two sites at which the standard deviation of the average 

ratio of the monthly mean concentrations is lowest (Cape 

Grim and South Pole) are those sites where we expect the 

97 
TABLE 3. Monthly Mean CH4 Data (ppbv) From 5-L 

Glass Flask Samples Collected at SMO During 

1984-1988 and Analyzed at CSIRO 

Month 1984 198S 1986 1987 1988 

Jan. 1S71 1612 1619 1607 

Feb. 1634 

March 1S63 IS86 1619 1618 

April 1572 1591 1S98 1607 1628 

May 1578 1591 1611 1604 1638 

June 157S 1593 1613 1629 

July 1586 1601 1616 1626 1638 

Aug. 1S87 1591 1614 1625 1637 

Sept. 1586 1599 1610 1631 1635 

Oct. 1588 1604 1608 1627 1636 

Nov. 1594 1604 

Dec. 1590 1602 1602 1620 1650 

Annual Mean 1581 1593 1608 1619 1632 

The average number of flasks filled per month is one. 

TABLE4. Monthly Mean Methane Data (ppbv) From 5-L 

Glass Flask Samples Collected at SPO During 

1984-1988 and Analyzed at CSIRO 

Month 1984 1985 1986 1987 1988 

Jan. 1570 1581 1599 

Feb. 1551 1568 1596 1607 

March IS51 1569 1584 1596 1606 

April !SSS 1574 1582 1600 1605 

May 1565 1583 1589 1606 1612 

June 1573 1591 1600 1615 1619 

July 1581 IS94 1606 1619 1627 

Aug. JS86 1603 1611 1626 163S 

Sept. 1602 1616 1629 163S 

Oct. JS87 1602 J6i7 1639 ~OV. 1586 1596 1611 1628 163S 

Dec. 1578 1587 1607 1613 

Annual Mean 1571 1587 1599 1613 1622 

The average number of flasks filled per month is one. 

lowest short-term variability in atmospheric CH4 concentrations, because they are the most distant from the known CH4 

sources (largely concentrated in the northern hemisphere). 

These findings suggest that the overall level of agreement 

between the CH4 calibration scales in these two programs is 

better than about 3 ppbv . For a more precise_ definition of 

the relationship between these calibration scales, we need to 

carry out a regular exchange of appropriate standard gases. 

This has now commenced. 

TABLE 5. Monthly Mean CH4 Data (ppbv) From Glass snd 

Stainless Steel Flask Samples Collected at Cape Grim, 

Tasmania, During 1984-1988 and Analyzed at CSIRO 

Month 1984 198S 1986 1987 1988 

Jan. 1S61 1S69 1S83 1S98 161S 

Feb. ISS7 IS6S !S80 IS93 1606 

March 1S56 1S69 1583 IS97 1606 

April 156S IS74 1588 1604 1612 

May 1S72 1S82 1599 1612 1620 

June 1S79 1586 1601 1615 1626 

July 158S IS94 1610 1626 1634 

Aug. 1593 1602 1614 1628 1638 

Sept. 1591 1603 1616 1628 1642 

Oct. 1S87 1602 1616 1630 1642 

Nov. JS84 IS97 1612 1626 1634 

Dec. 1580 IS88 1606 1619 1628 

Annual Mean 1574 1S86 1601 1615 1625 

The average number of flasks filled per month is 20-25 

TABLE 6. Average of the Monthly Mean CH4 

Concentration Ratios (CMDL/CSIRO) 

Observed at the Five Sites for 1984-1988 

Station Ratio No. Months 

BRW 1.000 (0.007) 39 

MLO 1.000 (0.008) 51 

SMO 1.000 (0.006) so 

Cape Grim 1.000 (0.002) 57 

SPO 1.000 (0.003) S4 

The number in parentheses is one standard deviation of the mean. 

The last column refers to the number of months in which a monthly 

value was obtained from both programs. 

Other important elements to consider in the comparison of 

the CSIRO and CMDL CH4 data sets are the differences 

between the two programs in both flask types and sampling 

methods. The latter has been the subject of an ongoing 

cooperative study at Cape Grim since 1984. The first results 

of this study have been reported by Steele at el. (1989) and 

Conway et al. (1990), and indicate clearly that there are no 

significant differences in the CH4 concentrations obtained 

when air samples are collected by the different sampling 

methods. To address the issue of different flask types, a very 

detailed comparison of the CSIRO and CMDL flask records 

at Cape Grim is now being undertaken. 

98 
1700 ~ 

I 

CH4- Maun a Loa 

1700 Ia - CSIRO . - NOAA 0 • • a I- 1650 ••• • •a 

·~ •11 ~•Da • oa • ••~o 

,.......... 

> 

....0 

0... 

1600 -

0... 1 650 - ....__,, 

~ 1600 lo •• 

Cl:'.: 

01 1550 '-

c 

x 

o olll 

• 

I 

I 

a 8 a 

• !i!. 

2 I I 

CH4 - Cape Grim 

1 650 ._ o - CSIRO 

• - NOAA 

1 600 '-

I I 

CH4 - South Pole 

1 650 ~ a ·- CSIRO 

• - NOAA 

1600 ~ 

I 

1984 

I 

I 

a 

I 

a 

!• •o ·~~·i•~•~ • a• •• 0 •o! 0 0 

I 

I 

I 

I 

1986 

I 

-

-

I 

0 

0 

-

-

I 

-

I 

-

I 

-

I 

1988 

Fig. 1. Monthly mean CH4 mixing ratios (ppbv) from air samples collected in 5-L glass flasks at the four CMDL baseline observatories and 

in glass and stainless steel flasks at Cape Grim, Tasmania, all analyzed at CSIRO (open squares). The monthly mean data at these five same 

sites from the CMDL program are also shown (filled triangles). 

99 
4. REFERENCES 

Conway, T.J., L.P. Steele, P.M. Lang, and L.S. Watennan, 

NOAA/GMCC carbon dioxide and methane measurements at 

Cape Grim, in BaseliM Atmospheric Program (Australia) 1988, 

edited by S. Wilson and G.P. Ayers, CSIRO, Melbourne, 

Australia, in press, 1990. . 

Francey, R.J., P.J. Fraser, and G.I. Peannan, The CSIRO latitudinal 

gradient study of C02 isotopes, in Geophysical Monitoring for 

Climatic Change, No 17: Summary Report 1988, edited by J.W. 

Elkins and R.M. Rosson, pp. 91-93, NOAA Air Resources 

Laboratory, Boulder, CO, 1989. 

Fraser, P.J., Atmospheric methane and carbon monoxide 

observations at Cape Grim, Tasmania, in Baseline Atmospheric 

Program (Australia) 1981-1982, edited by R.J. Francey, 

Canberra Publishing and Printing Co., pp. 25-36, Canberra, 

Australia, 1984. 

Fraser, P.J., P. Hyson, R.A. Rasmussen, A.I. Crawford, and M.A.K. 

Khalil, 1986, Methane, carbon monoxide and methylchlorofonn 

in the southern hemisphere, J. Atmos. Chem., 4, 3-42, 1986. 

Lang, P.M., L.P. Steele, R.C. Manin, and K.A. Maurie, Atmospheric methane data for the period 1983-1985 from the 

NOAA/GMCC global coopentive flask sampling network, 

NOAA Tech. Memo. ERL CMDL-1, 90 pp., NOAA 

Environmental Research Labontories, Boulder, CO, 1990o. 

Lang, P.M., L.P. Steele, and R.C. Manin, Atmospheric methane 

data for the period 1986-1988 from the CMDL global 

cooperative fluk sampling network, NOAA Tcclt. Memo. ERL 

CMDL, 108 pp., NOAA Environmental Researcli Laboratories, Boulder, CO, in preu, l 990b. 

Rumuuen, R.A., and M.A.K. Khalil, Atmospheric methane (CHJ: 

Trends and seasonal cycles, J. GeoplsY1. Ru., 86, 9826-9832, 

1981. 

Steele, L.P., P.J. Fnser, R.A. Rasmu11en, M.A.K. Khalil, T.J. 

Conway, A.I. Crawford, R.H. Gammon, K.A. Manrie, and 

K.W.Thoning, The global distribution of methane in the 

troposphere, J. Atmo.r. Chun. 5, 125-171, 1987. 

Steele, L.P., T.J. Conway, L.S. Watennan, and P.M. Lang, The 

NOAA/GMCC mea1uremenu of CH4 and C02 from fluk air 

samples at Cape Grim, in Ba.ulitu Atmo1pltcric Program 

(Australia) 1987, edited by B.W. Forgan and G.P. Ayers, pp. 

48-50, CSIRO, Melbourne, Au1tnlia, 1989. 

100 
Secular Variation in the Carbon-13 Content of Atmospheric Carbon Dioxide 

I. FRIEDMAN, J. GLEASON, A.ND A.WARDEN 

U.S. Geological Survey, Denver, Colorado 90225 

1. INTRODUCTION 

Measurements were made of the o13C of atmospheric C02 , 

separated cryogenically from samples of air collected from 

early 1981 to early 1989 at MLO, BRW, SMO, and SPO. 

2. EXPERIMENTAL PROCEDURES 

The efficiency of the C02 separation and purification was 

checked by filling our stainless steel 10-L flasks with air 

from a single high-pressure cylinder. A series of 16 air 

samples was processed over a period of 4 months in 

1980-1981, yielding an average S13 C value of -8.081%0 with 

a standard deviation of 0.034%0. A similar experiment was 

carried out over a period of 2 weeks in 1989 when six 

replicate samples from another high-pressure cylinder that 

was filled at the same time as the first cylinder gave an 

average S13 C value of -8.140%0 with a standard deviation of 

0.0020/oo. The difference of 0.06%0 between the two sets of 

determinations carried out 8 years apart is not considered 

significant in view of the long storage time and the fact that 

the air in each fl ask might have initially been slightly 

different. 

3. CORRECTION FOR N20 

During the cryogenic separation of C02 from air, N20, 

present in air at about 0.3 ppm, is separated together with the 

C02. Because N20 has the same isotopic masses as C02, it 

interferes with mass spectrometric analysis of the C02, and a 

correction must be applied to the final 013 C results [Craig 

and Keeling, 1963 ]. Al though the theoretical correction is 

about +0.32%0, in practice the correction depends upon the 

relative efficiency of ionization of the two gases in the 

cj 

..... 

i:O 

·-

:.> 

gi -.... 

u c. 

"8 

c 

() 

,, 

"" 0 

0 

· 1 

· 2 

-3 

~ 

· 5 

-6 

-7 

001 

Cnrbon Dioxide - NitroU9 Oxide l\lli-tures 

Exporimen1at m .ittutos 

T ;\·r 

A" 

y • · 036 · 2 12X R "'2 .. 0 99 

~\ 

f\lole % ~20 in co! . ., 

Fig. I. The observed change in S 13C (per mil) as N20 is added to 

C02. The proponion of N20 is given in mole pcrcenl. 

particular mass spectrometer used for the analysis. For 

example, Mook et al. [ 1983] found that their instrument 

required a correction of about +0.18 ± 0.06%0. This value was 

obtained by Mook et al. by passing C02 over copper metal at 

700'C. We could not detect a change in S13C greater than 

0.01 %0 upon repeated passage of our atmospheric co2 over 

copper metal at 700'C which should remove the N20 by 

reducing it to nitrogen. 

To determine the efficiency of ionization of N20 for our 

mass spectrometer, we made a series of mixtures of tank 

N20 and pure C02 prepared by the reaction of 100% 

phosphoric acid with our standard limestone. The data 

shown in Figure 1 indicate that the efficiency of ionization 

of N20 in our instrument is equal to that of C02. Accordingly, all the o13C data reported in this paper have been 

corrected by adding 0.320/oo to the analytical values. 

4. RESULTS 

4.1 . COMPARlSON W!TII RESULTS OF PREVIOUS 

INVESTIGATORS 

There was an overlap in sample collection between Mook 

et al. [1983] and our group at MLO during 1981 and at SPO 

during the latter one-half of 1981. Figure 2 is a plot of both 

South Pole 

. 7 .0 +..._.._.._.__.. ............. ..._ ........ ._... .................. ..._.._'-+ 

E -7.5 

... 

(!) 

0. -8.0 

cJ 

.., -8.5 ;;c, 

-9.0 

1095 

E -7.5 

.... 

(!) 

0. -8.0 

cJ 

.., -.8.5 

"° 

0 

~ Mooketal. 

e Friedman et al. 

1980 1981 1982 

1460 Date 1825 2190 

MaunaLoa 

~ Mooketal. .... _.,.,__ Friedman et al. 

1980 1981 1982 

365 Date 730 1095 

Fig. 2. o13C values from Mook et al. [ 1983) and from the current 

analysis, for samples collected al SPO and MLO. 

101 
MaunaLoa 

-6.5 380 

375 

- -7.0 370 ·- E E co 365 0. .... -7.5 0. v Cl 360 0. M 

0.. -8.0 355 0 

u I u 

"' > 350 

(,Q -8.5 345 

340 

-9.0 335 

0 365 730 1095 1460 1825 2190 2555 2920 3285 3650 

Point Barrow 

-6.5 390 

1983 1985 1987 1989 

-7.0 

.. J\ . 

+0.006 per mil/year 

~ 380 

- -7.5 . t1. E --E co ._,,,. ... -~ oi ... f 370 0. 

.... -8.0 '''If 0. 

v Cl C-13 0. i 360 M 

-8.5 C02-ppm ."'! .. 0 0.. . ·~': .. u 

> -9.0 - ,-. . ' 350 u .... .. . . • . : 

~ ',t • . . . . (,Q . ~ . ..,. . ~ . ... i.: -9.5 .. • 

'"' 

.. a 340 ./ . . . . .. .., 'i ••• +1.41 ppm/year 

-10.0 330 

0 365 730 1095 1460 1825 2190 2555 2920 3285 

Samoa 

-6.5 - 368 

1981 l1983 1985 1987 1989 

-7.0 -0.028 per mil/year 363 

--- :: I! • E E co ~ ... .,, :: ~ 358 0. .... -7.5 ~~!~ !"• 1 • 0. v Cl 

0. Ht • 353 M 

• 0.. -8.0 1o 0 

u I --- C-13 348 u .... > • ,. (,Q ....•... C02-ppm -8.5 343 

+1.54 ppm/year 

-9. 0 -r-,....-.;r=;;:;;...,...,...,....,...,...'l"'T" .............. ....,.. ....... .,...,..,...,. .............................................. ...,.., ................................................... +- 338 

-

E ~ .... 0 v 

0. ~ 

u::i 

u I 

"' > (,Q 

0 365 730 

-7.5 

-8.0 

-8.5 

1095 1460 1825 2190 2555 2920 3285 

South Pole 

+1.45 ppm/year 

350 E 

0. 

0. 

0 "' 

340 u 

-9.0 +;: ..... 'OT'l..,...,l""O'T,....,.......,.,.,..,.,..,.,.......,.,..,..,...,.,.,..~ ........... ......, ........................... ---"""" ..................... ...+- 330 

0 365 730 1095 1460 1825 2190 2555 2920 3285 3650 4015 4380 4745 

Date 

Fig. 3. o13C (per mil) and C02 concentration (ppm). Data from Mook et al. [1983) for SPO and MLO are included in the plots. All sample 

analyses were made relative to the Vienna PDB air standard. C02 concentration data are from CMDL and from Mook et al. [1983). 

102 
sets of data for the two collection sites. Our data deviate 

from those of Mook et al. during two periods at MLO. We 

have no explanation for this. However, the remainder of the 

MLO data as well as the data from SPO show good agreement between the sets of data from both laboratories. In 

assessing Jong-term changes in o13C, we have included the 

Mook et al. (1983] MLO data for 1980 and their SPO data 

for 1977-1980. 

4.2. DISCUSSION 

The results shown in Figure 3, which include data from 

Mook et al. (1983], indicate that the Jong-term changes in 

li13C are -0.012%0 yr1 at MLO (1980-1989), -0.028%0 yr1 at 

SMO (1981-1989), and -0.016%0 yr1 at SPO (1977- 1989). 

Although the record at BRW indicated a change of +-0.006%0 

yr1 (1981-1989), the large seasonal changes in 1i13 C at this 

station make this value suspect. Seasonal changes in li13 C at 

MLO and BRW can be explained by the uptake of C02 by 

plants during the summer, which has a delta value of 

approximately -27%0. 

In addition to seasonal changes in 1i13C, we observed large 

changes of about -0.4%0 at MLO, SMO, and SPO that were 

coincident with the 1982-1983 El Nino. No such change was 

observed at BRW. A smaller change in 1i13 C that may be 

related to the 1985 El Nino was observed in samples from 

SPO collected in late 1985 through early 1986. These 

effects of the El Nino emphasize the importance of 

ocean-atmosphere exchange on the C02 cycle. 

5. REFERENCES 

Craig, H., and C.D. Keeling, The effects of atmospheric N20 on 

the measured isotopic composition of atmospheric C02, 

Geochim. Cosmochim. Acta, 27, 549-551, 1963. 

Mook, W.G., M. Koopmans, A.F. Carter, and C.D. Keeling, 

Seasonal, lati1udinal, and secular variations in the abundance 

and isotopic ratios of atmospheric carbon dioxide, I, Results 

from land stations,!. Geophys. Res., 88, 10,915-10,933, 1983. 

103 
Snow Bunting Nesting Study at Barrow, Alaska 

JOHN C. GEORGE, KIRSTEN BAGNE, ANo MARC LEWBERGER 

Departmel'I/ of Wildlife Managemel'I/, North Slope Borough, Barrow, Alaska 99723 

1. INTRODUCTION AND BACKGROUND 

Snow buntings (Plectrophenax nivalis) are obligate cavity 

ncsters, yet they do breed above tree line on the North Slope. 

They typically nest in or on artificial structures along Alaska's 

North Slope and in rocky crags in the Canadian Arctic [Johnson 

and Herter, 1989). It would seem that such species would be 

"nest limited" in the Alaskan Arctic since they require manmade 

structures as a nesting platform. 

The Department of Wildlife Management undertook the 

nesting project in an attempt to increase the number of nesting 

passerine birds in the Barrow area. The department also wanted 

to do a small demonstration project to show some beneficial 

aspects of wildlife management to the people of the North 

Slope. Our working hypothesis was that artificial nests would 

be readily used by snow buntings in the Barrow area and that 

their numbers would increase. 

2. OBJECTIVES 

The major objectives of the study were: (1) erect artificial 

nest boxes around the village of Barrow; (2) monitor the use of 

artificial nest boxes by passerine birds and gather life history 

data if possible, with emphasis on nesting initiation, time of 

hatching, numbers of eggs laid, and numbers of young fledged; 

and (3) increase the nesting population of snow buntings in the 

Barrow area. 

3. METHODS 

On May 2, 1989, 14 bird houses were erected near Barrow 

and the Northern Arctic Research Laboratory, primarily on 

telephone poles. We checked the houses at least once each 

week for bird use, and also logged sightings of other bird 

species during the inspections. The bird houses were 15.5 cm x 

15.5 cm x 15.5 cm boxes with a 5-cm-diarneter hole. They were 

labeled with sequential numbers from 1 to 14. 

During the 1989 season, snow birds nested in 3 of the 14 

boxes (numbers 2, 6, and 10) and possibly successfully fledged 

young in one of them. The basic results of the nest observations 

are summarized in Table 1. Nest building began on about May 

·27, and egg laying started by about June 16. Hatching began 

June 30 in nest number 6. The young began fledging around 

July 15-20. 

During the 1990 season, four nest boxes were used of which 

two appeared to be successful. The basic results of the nest 

observations are summarized in Table 1. No data were gathered 

on nest building. Egg laying began about June 4. Eggs were 

noted to have hatched by June 13-somewhat earlier than in 

1989. Young from two nests appeared to have successfully 

fledged, in particular in nest number 2. 

TABLE 1. Basic Snow Bunting Nesting Study 

Nest Nesting Egg Date Number 

Site Building Laying Hatched of Eggs Comments 

1989 

2 5 Nest failed(?) 

6 May27 June 16-23 June 30 5 Nest failed 

10 <.June 16 <.June 23 >3 Probably 

successful 

1990 

<.June 15 June 18 6 Two chicks 

fledged(?) 

by July 2 

2 June 4 June 11-13 7 Five fledged 

by June 27; 

two eggs 

failed 

7 <.June 25 5 

II June 4 <.July 2 6 

Dates are approximate in most cases, u neats were checked approximately once per week. 

Nest building begins in late May in the Barrow area. Egg 

laying appears to begin by June 4, but can continue into late 

June. Hatching dates appear to be variable, ranging from 

roughly June 11 to July 2. Observations, however, were not 

frequent enough to determine all hatching dates with great 

accuracy. The females generally laid 5-7 eggs. In past years, 

we have noted the young remaining (and feeding) in the Barrow 

area until November. For both years studied, three of seven 

nesting attempts (43%) appeared to be successful. It is not 

known why other nests failed. 

Initially, it seems, we can refute our hypothesis that snow 

buntings are nest-limited near Barrow. However, it may be the 

case, as for other species, that the birds take several sea.sons to 

become familiar with a nest site before they start using it 

(George Divoky, personal communication, 1989). Another 

possibility is that other factors are limiting snow bunting 

populations near Barrow. 

Acknowledgments. We acknowledge George Divolcy foe auiltance in 

nest design and Lane Franidi for coostn1ction of the nest boxe1. The 

auistance of NOAA/CMDL staff for allowing us to place nen boxes on 

their buildings and power poles is appreciated. 

4. REFERENCE 

Johnson, S., and D. Herter, The birds of the Beaufort Sea, BP 

Exploration (Alaska) Inc., Environmental and Regulatory Affain, 

Anchorage, AK, 265-267, 1989. 

104 
A New Look at Optical Depth Retrieval With the Multiple 

Field of View Sunphotometer 

PAUL F. HEIN, JOHN M. DAVIS, AND STEPHEN K. Cox 

Colorado Stale University, Departnunl of Atmospheric Science, Fort Collins, Colorado 80523 

1. INTRODUCTION 

The multiple field of view (MFOV) sunphotometer was 

designed to infer the optical thickness of clouds from the 

surface by viewing the direct plus diffuse components of 

solar radiance. The instrument was deployed at MLO in 

1987 and has been collecting data since then. Recently a 

new approach for retrieving the desired optical depth was 

developed that not only allows simpler processing of the 

data, but also gives new insight into limitations on the upper 

range of optical depths that can be measured. 

2. DESCRIPTION OF THE INSTRUMENT 

The MFOV sunphotometer was first built and tested at the 

Department of Atmospheric Science at CSU to determine the 

optical thickness of clouds of small to moderate optical 

depth, such as are common in layers of cirrus cloudiness 

[Raschke and Cox, 1983). The instrument consists of five 

high-quality silicon photodetectors whose fields of view 

(fov) are coaligned and deployed so that the central line of 

sight tracks the solar disk (see Figure 1). The detectors have 

a broad response in the visible portion of the spectrum; thus 

the optical depth 't must be interpreted as a broadband 

parameter. 

The instrument is mounted on an equatorial tracking 

device for continuous alignment throughout the day. Each 

fov is of different size (2, 5, 10, 20, and 28' full angle) to 

detect differences in the nearly forward-scattered radiative 

field. The initial application of the instrument relied on 

Fig. 1. Schematic of the MFOV sun photometer. 

concurrent pyrheliometric measurements to provide a 

direct-beam trartSmittance that was used to scale the output 

of the photometric detectors to radiometric values. The 

measurements in each fov were interpreted by Monte Carlo 

modeling of the amounts of irradiance expected at each 

detector viewing clouds of various optical thicknesses. A 

slightly different method of analyzing the data is now 

presented that not only is simpler, but also gives insight into 

the upper limit of retrievable optical depths. 

3. DATA ANALYSIS 

A Monte Carlo model was used to calculate the solar 

irradiance expected in each of the fov. The modeled 

irradiances were divided by the extraterrestrial irradiance to 

form "transmittances" for each fov. The ratios are not 

transmittances in the strictest sense of the definition, since 

scattered radiation is included in the measurements. 

Denoting the ratios in each fov by T(fov), where fov is the 

set (5, 10, 20, 28), other ratios were taken, namely the ratios 

of T(fov)ff(28). Doing so eliminates the need for specification of a scaling factor when the same ratios are formed from 

measured values; i.e., it allows the modeled and measured 

ratios to be used independently to infer the optical depth. 

Figure 2 depicts the modeled transmittance ratios as a 

function of fov for various optical depths, 't. The values 

were calculated for a solar zenith angle of O' and a surface 

albedo of 0.15. A stratocumulus cloud droplet distribution 

was used in Mie calculations to provide the single-particle 

scattering parameters. The calculation was performed for the 

visible portion of the spectrum. 

It is obvious from the convergence of the curves (Figure 

2) at optical depths near 10.0 that the method will not be 

usefui at large optical depths. Furthermore, we show as 

follows that the shapes of the curves have a physical 

interpretation related to the radiation scattered into each 

detector: In a monochromatic sense, the trartSmittance may 

be written simply as T = e~. If the measurement by a 

particular detector is denoted by 

T(fov) =exp (-['t - 't,(fov)]}, (1) 

where 't, is a parameter that accounts for the radiation 

scattered into the detector's fov, effectively increasing the 

reading, then the ratio of two such measurements, depicted in 

Figure 2, may be expressed as 

T(fov) W'S) = exp ['t, (28) -'t, (fov)) . (2) 

105 
1.0 

09 

0.8 T = 

07 •• .... 

29 0 .. T = O) 0.6 (", • • .··e:,. ~ v ......_ 0 c, ~ 

T = 4 4 > " .... 2 0. ·1 tT = 5J 0 

03 

T 7.2 • 

0.2 [ T 0 6 

- · 

0.1 6 

oul T = 10 0 

0 5 10 15 20 25 30 

r1elt1 of View (oegrees) 

Fig. 2. Modeled transmittance ratios versus fov for various optical 

depths 't, a solar zenith angle of o·, and a surface albedo of 0.15. 

In (2), it is assumed that the actual transmissivity is the same 

for all detectors, which should be the case if the calibration 

is correct. Thus each curve , according to this formulation, 

decays exponentially in a manner related to the difference in 

the exponents that describe the amount of energy scattered 

into the detectors at each fov . For small 't , multiple 

scattering is small· and so is the value of the exponent. The 

curve at 't = 1.5 shows a relatively small decay as a result. 

Since the exponent in (2) is expressed as the difference 

between the optical depths attributed to scattering into the 

fov, and since the volume scattering coefficient may be 

expressed in terms of an integral of the phase function over 

scattering angles, it is reasonable to expect the exponent to 

also be related to the difference in the angles themselves, at 

least in the first-order sense. If so, a reasonable guess at 

fitting the curves in Figure 2 would be 

T(fov) "T<m =exp [-a(-c) (28 - 0rov )] , (3) 

where a(-c) is an optical depth parameter and 0 rov is the 

angular fov. When this is done and the values of a(t) are 

plotted as a function of 't, a nearly linear relationship results 

for 't < 10 (Figure 3 ). Thus for small optical depths, the 

value of a(-c) is nearly linearly related to't. The slope of this 

line may change with different types of scattering functions 

and with solar zenith angle, and is the .subject of future 

research; however, once the linear relationship is obtained in 

this form, it is a simple matter to relate the ratios of 

transmittances to the optical depth. For example, if the 

relationship in Figure 3 is expressed as a(-c) = m't + b, where 

m is slope and b is intercept, then the optical depth i~ 

obtained as 

10 

9 

8 

7 

0 6 .... 

~ <lJ 5 E 

~ 

0 

a. 4 

3 

2 

0 

0 5 10 15 20 25 

TAU 

Fig. 3. The parameter a('t) plotted as a function of 't, for a solar 

zenith angle of o·. 

't = _..!_ { ln[T(fov)/T(28)] _ b} m 28 - 0rov (4) 

The kink in the fit of a("C) is exaggerated by the lack of 

data points for 10 < 't < 20. It is another indication, as seen 

in Figure 2, that the MFOY sunphotometer optical depth 

retrieval should be used for optically thinner clouds and only 

as a fl ag of thicker clouds when the inferred thickness is 

larger. 

4. FUTURE RESEARCH 

In addition to continued maintenance of the MFOV 

sunphotometer at MLO and ongoing data collection, a 

modeling effort is indicated to examine the behavior of the 

sensitivity of the algorithm for computing 't to changes in 

solar zenith angle and cloud microphysics. For example, 

cirrus cloud crystals may produce a significantly different 

value for the slope m in (4) in which case it may be 

necessary to search for additional information on cloud type 

in the MFOV sunphotometer signal. This signal may be 

found by incorporating phase function information into the 

exponent of (3). Alternately, with a more refined choice of 

the fov number and precision, ways may be found to extract 

properties of the scattering phase function and the optical 

depth simultaneously. 

5. REFERENCE 

Raschke, R.A., and S.K. Cox, Instrumentation and technique for 

deducing cloud optical depth, J. Clim. Appl. Meleorol., 22 , 

1887-1893, 1983. 

106 
Tropospheric Nitrogen Oxide Measurements During Spring at Barrow 

R. E. HONRATH AND D. A. JAFFE 

University of Alaska, Geophysical lnstituu and Department of Chemistry, Fairbanks, Alaska 99775.{)800 

1. INTRODUCTION 

Nitrogen oxides are critical in the chemistry of the 

atmosphere [Crutzen, 1979]. By controlling the photochemical production of ozone and hydroxyl radicals in the 

troposphere, NO, (NO + N02) plays a central role in 

atmospheric photochemistry. Additionally, NO, is a precursor 

to nitric acid (HN03), a major constituent of acid rain 

[Galloway and Likens, 1981). Other nitrogen oxides, such as 

peroxyacetyl nitrate (PAN), may have a significant part in the 

global distribution and lifetime of nitrogen oxides [Singh, 

1987]. The concentration of total reactive nitrogen (NOY = 

NO+ N02 + HN03 + Np5 +PAN+ RON02 +particulateNO) + ... ) can be used as a surrogate for the individual species 

and can provide valuable information on transport and removal 

processes, especially in situations where measurements of 

individual species are limited by resources or instrument 

sensitivities. In addition, it is possible that unknown and/or 

unmeasured compounds make up a significant fraction of the 

total NOY reservoir in remote areas [Singh, 1987]. 

The role of anthropogenic nitrogen oxides in changes in 

Arctic tropospheric ozone concentrations is not well understood. Surface ozone at BRW during summer has shown a 2% 

yrl increase since 1973 [Oltmans and Komhyr, 1986]. 

Industrial nitrogen oxide emissions from the Prudhoe Bay area 

could be responsible for the observed summer surface 0 3 

increase, although to date the available summer NOY data do 

not support this hypothesis. Alternatively, photochemical 0 3 

production resulting from lower-latitude NO, sources could 

also contribute to the observed 0 3 increase. 

2. EXPERIMENTAL PROCEDURES 

NO and NOY were measured from March 2 to April 7, 1989, 

using a high-sensitivity chemiluminescent detector built at the 

University of Alaska, Fairbanks [HonraJh and Jaffe, 1990; 

Jaffe et al., 1990). NOY is detected as NO following reduction 

in a heated converter. The accuracy and precision of low-level 

NO and NOY measurements at BRW have steadily improved. 

The detection limit during the spring 1989 measurements was 

75 ppt for NO, and about 120 ppt for NOY. The current 

detection limit for this instrument is 5 ppt for NO or NOY, with 

an estimated uncertainty of ±15% at concentrations well above 

the detection limit. Since NO, is produced in virtually all 

combustion processes, it is necessary to carefully screen the 

data to eliminate local impacts on the data. To remove any 

possibility of local sources affecting the measurements, we 

screened the data by wind direction and variability. Data 

shown here were obtained only when the winds were not from 

the direction of significant local sources and exhibited low 

variability. 

3. RESULTS 

Two types of measurement conditions were identified in the 

data record after screening by wind direction and arribient 

variability [Jaffe et al., 1990]: background periods and events. 

Background periods correspond to times when NO and NOY 

concentrations were constant and low relative to values in the 

overall data record. Inspection of the raw data also revealed 

several events, during which ambient NO and NOY concentrations changed smoothly and reached high values even though 

wind was generally from the clean sector (5'-130'). Maximum 

NOY levels exceeded 3 ppb during each event. 

3.1. BACKGROUND PERIODS 

Eleven background periods were identified. Concentrations 

varied very little during individual periods, but larger 

differences were observed among the periods. A histogram of 

all NOY measurements during the springtime background 

periods (N = 885) is shown in Figure l. Median NOY levels 

during each of the 11 background periods ranged from 280 to 

850 ppt, with an overall median of 616 ppt. NO 

concentrations during background periods were all below our 

detection limit of 75 ppt. On the basis of a photostationarystate calculation, NO, levels must have been below 145 ppt, at 

least during clear midday periods [Jaffe et al., 1990). 

An analysis of 850 mb back trajectories [Jaffe et al., 1990; 

Harris, 1982] shows that these measurements are consistent 

with the understanding of a generally contaminated reservoir 

of air over the Arctic basin during winter and spring, 

.. 

c 

go "' 2: -., 

8 

0 

c 

"' 

~ 

.. Cl. .... 

I uJ. I 

11 • .. 250 $0) 7~ ,000 1250 

NOy Concen1ra11on (pp!) 

Fig. I. Histogram of background NOY concentrations during spring 

1989 at BRW. 

107 
regenerated by episodic transport from source regions. The 

relatively constant and high NOY levels during Arctic 

trajectories are indicative of a high-NOY Arctic reservoir. 

Lower NOY levels during periods of transport from the south 

are probably due to enhanced scrubbing of air by the greater 

frequency and amount of precipitation in those regions. 

Interestingly, spring concentrations were higher than summer 

concentrations, even during southerly flow, a finding that is 

consistent with the increased lifetime of NOY reservoir 

compounds, such as PAN, during winter [Singh and Hanst, 

1981]. 

3.2. EVENTS 

During this campaign, four identifiable pollution events 

were observed, lasting from 12-60 hours each, as shown in 

Figure 2. For event!, NOY reached a peak of 16.4 ppb, while 

NO reached 1.4 ppb. The suddenness with which such events 

occur and the extremely high NOY concentrations observed are 

not characteristic of arctic haze at a background site. 

Moreover, the relatively smooth changes in NOY concentration 

during such events contrast sharply with the well-characterized 

high-variability signatures of local (Barrow) pollution sources 

[Honrath and Jaffe, 1990]. 

Figure 3 shows a plot of the observed NOY concentrations 

during events and background periods in 1989 versus the local 

wind direction. The events were observed to occur when wind 

directions were in the range of 98° to 233 •. Highest NOY 

concentrations were observed when local winds were from 

l10° to 120°, suggesting that the nitrogen oxide source 

responsible for these events is in that sector. The only major 

NO source in that direction is the Prudhoe Bay oil production 

co~plex, at l ll 0 from BRW and approximately 300 km 

distant. The NO. emissions from those facilities arise from 

natural gas combustion and are estimated at 10,000-15,000 

metric tons yr1 (J. Coutts, personal communication, 1989). 

Other data, including estimated NO. concentrations and S02 

and SO~ filter measurements, are consistent with a Prudhoe 

Bay source. It is interesting to note that Prudhoe Bay was first 

suggested as a possible influence on the BRW record by Radke 

et al. (1976], based on measurements of condensation nuclei at 

BRW during 1970. 

Pollution episodes at BRW due to a non-local sources, 

having a very similar appearance, have been previously 

attributed to long-range transport events [Hansen et al., 1989]. 

A comparison of these nitrogen oxide data with black carbon, 

C02

, and CH4 data is currently under way and should prove to 

be very useful in characterizing these events. 

4. SUMlv'IARY 

As a result of this measurement program, we have learned 

much about nitrogen oxides in the Arctic atmosphere. In 

particular we have found the following about background NOY 

and NOY events: 

(I) Background NO . NOY concentrations in the Arctic y In . are significantly higher in spring than in summer. spnng, 

surface NOY levels at BRW appear to be comparable to 

concentrations in the free troposphere outside of Arctic haze 

layers [Dickerson, 1985], with haze-layer concentrations being 

about twice as high. In addition, springtime NO concentra- '1 

tions during southerly flow (as indicated by 850 mb 

trajectories) were 50-70% of the levels observed when 

trajectories indicated that Arctic air was being sampled at 

BRW. During southerly flow, springtime NOY concentrationa 

were higher than those in summer, providing evidence for an 

increased NOY lifetime during winter. NO. concentrations in 

the arctic during spring are estimated to be 0-20% of NOY 

concentrations. 

Event 1 

•t1 tw!S •11 

Event 3 

- - ..... 

:11=:;:::::;: ========~Event4~1 9G'•O ~12 tn!u .,;;,, ~11 ~ to'22 

Day ol Year I HOUt (Univetsal Timel 

Fig. 2. N?Y. concentrations during events observed in the spring of 

1989 at BRw. 

ea 

6 • Event 1 

• • Event 2 

• • Event 3 o • Event 4 

• • Background Periods 

120 ,., 240 

Wind Direction - - Fig. 3. NO concentrations during cvenu and background periods 

(spring 1989J versus surface wind direction at BRW. 

108 
(2) NOY events. Substantially elevated NOY concentrations (to 16 ppb) were observed in the spring of 1989 during 

four events lasting from 12-60 hours. Substantial evidence 

suggests that emissions from the Prudhoe Bay industrial 

region were responsible: (1) slow and smooth concentration 

variations during the events indicated that local (Barrow) 

sources were not the cause; (2) the correlation with local wind 

direction indicated that the source was in the 110' :120' sector, 

consistent with Prudhoe Bay, which lies at a 111' bearing from 

Barrow; (3) the ratio of NO,: NOY estimated for these events is 

very high (to 0.87), indicating that the NOY enrichment was 

almost entirely due to NO, and that very fresh NO, emissions 

were responsible for the events; and (4) filter measurements of 

so; and S02 did not indicate enrichment of sulfur compounds 

during the events. This is consistent with a source, such as 

Prudhoe Bay, which is rich in NO,. 

Although the CMDL site at Barrow is in a remote region, it 

is affected by local, regional, and global-scale pollutant 

sources. To differentiate between these sources, we must 

select data collected at such a site with great care so that 

measurements are representative of specific, identifiable air 

masses. Our data indicate that atmospheric transport processes 

can bring different air masses to the BRW site on a time scale 

of hours. Daily, weekly, or monthly means may therefore not 

be adequate to discriminate between different air masses. In 

general, measurement systems that provide high time 

resolution data will provide greater insight into complex 

atmospheric processes at a site such as BRW. 

Aclcnowledg~nts. Trajectories were calculated by Joyce Harris 

(CMDL, Boulder, Colorado). W. T. Sturges, S.-M. Li, and the staff of 

BRW helped with sample collection. We are also thankful for 

assistance from the North Slope Borough Department of Wildlife 

Managemenl. This work was supported by NSF grant A TM 

88-14518. 

5. REFERENCES 

Crutz.en, PJ., The role of NO and N02 in the chemistry of the 

troposphere and stratosphere, Ann. Rev. Earth Planet. Sci., 7, 

443-472, 1979. 

Dickerson, R.R., Reactive nitrogen compounds in the Arctic, J. 

Geophys. Ru., 90, 10,739-10,743, 1985. 

Galloway, J.N., and G.E. Likens, Acid precipitation: The importance 

of nitric acid, Atmos. Environ., 15, 1081 -1085, 1981. 

Hansen, A.D.A., T.J. Conway, L.P. Steele, B.A. Bodhaine, K.W. 

Thoning, P. Tans, and T. Novakov, Correlations among 

combustion effluent species at Barrow, Alaska: Aerosol black 

carbon, carbon dioxide, and methane, J. Atmos. Chem., 9, 283 -299, 

1989. 

Harris, J.M., The GMCC atmospheric trajectory program, NOAA 

Tech. Memo. ERL ARL-116, Air Resources Laboratory, Rockville, 

MD, 1982. 

Honrath, R.E., and D.A. Jaffe, Measurements of nitrogen oxides in the 

Arctic, Geophys. Res. Lei/., 17, 611~14, 1990. 

Jaffe, D.A., R.E. Hanrath, J.A. Herring, and S.M. Li, Measurement of 

nitrogen oxides at Barrow, Alaska: Evidence for regional and 

northern hemispheric sources of pollution, J. Geophys. Res., 

submitted, 1990. 

Oltrnans, S., and W.P. Komhyr, Surface ozone distributions and 

variations from 1973-1984: Measurements at the NOAA 

Geophysical Monitoring for Climatic Change baseline observatories, J. Geophys. Res., 91, 5229-5236, 1986. 

Radke, L.F .. P.V. Hobbs, and J.E. Pinnons, Observations of cloud 

condensation nuclei, sodium-containing particles, ice nuclei and 

the light-scattering coefficient near Barrow, Alaska, J. Appl. 

Meteorol., 15, 982-995, 1976. 

Singh, H.B., Reactive nitrogen in the troposphere, Environ . Sci. 

Technol .. 21, 320-327, 1987. 

Singh, H.B., and P.L. Hanst, Peroxyacetyl nitrate (PAN) in the 

unpolluted atmosphere: An important reservoir for nitrogen oxides, 

G1oph-μ. Res. Lei/., 8, 941-944, 1981. 

109 
Chemical Analyses of Atmospheric Particulates and Gases at MLO 

C. R. JENSEN, X. CAI, AND W. H. ZOLLER 

University of Washington, Seattle, Washington 98195 

1. INTRODUCTION 

Atmospheric particulate samples have been collected 

continuously at MLO using the selective sampling system 

installed in 1979 [Parrington, 1983]. This system was 

originally designed to collect either upslope or downslope 

aerosol samples, based on wind direction, wind speed, time 

of day, and CN concentration. During conditions that did 

not fit into either upslope or downslope parameters, an 

interim sample was collected. In 1985 two changes were 

made. First, the separate upslope sampling was discontinued 

by setting only downslope parameters and making all other 

conditions interim. Second, 7LiOH-treated filters were 

added to collect downslope gases. Dow,nslope samples since 

1985 have therefore been collected on Teflon, Nuclepore, 

and treated filters, while the interim samples have been 

collected on Nuclepore filters. We are currently working on 

analyzing a backlog of samples from 1985 to the present 

using two methods: instrumental neutron activation analysis 

is used to characterize particulates collected on Teflon and 

Nuclepore filters; ion chromatography is used to measure 

water-soluble ions on the Teflon and Nuclepore filters, and 

absorbed gases on the treated filters. 

2. PRELIMINARY RESULTS AND DISCUSSION 

2.1. INSTRUMENTAL NEUTRON ACTIVATION ANALYSIS 

RESULTS 

Initial calculations for several elements collected on 

downslope Teflon filters show increased concentrations 

during the dust season (mid-February to July) as expected 

[Bodhaine et al., 1981; Parrington et al., 1983]. Figure 1 

shows this trend for Mn and V in 1987; the highest concentrations are in the spring, especially April and May. 

Mean concentrations for several elements during 1987 clean 

and dust seasons, and the ratios of dust to clean averages are 

given in Table 1. The predominantly crustal elements Al, V, 

and Mn show a fivefold to ninefold increase during the dust 

season, while the predominantly marine elements Na, Cl, and 

Br show only a twofold increase. 

2.2. ION CHROMATOGRAPHY ANALYSIS 

Figure 2 shows initial results for so; and S02 from April 

1989 to April 1990. Only one sample was collected for the 

2-wk period from the end of February to the middle of 

March 1990 due to a snow storm that closed the road to 

MLO. The so; measured on downslope Teflon filters snows 

no distinct trends. The increase from January to April 1990 

may indicate the beginning of the dust season, but more data 

are needed to confirm this. Unfortunately some data are 

missing for the spring of 1989, so that the trend in so; 

(•) 

V A U .o 

Mont.b 

G.7 

(b) 

... 

,,s 

"" O.• 

.€ 

OI) 

i:: O.l 

0.2 

0.1 

u 

Mont.b 

Fig. 1. Concentrations (ng m· 3) of (a) Mn and (b) V, 1987. Each 

sample is collected for I week. 

during the 1989 dust season is difficult to discern. The S02 

measured on downslope treated filters does not exhibit 

increased concentrations during dust seasons. The increase 

in S02 between September and December 1989 may be due 

to gaseous volcanic eruptions at Kilauea that reach the 

observatory when the eruptive clouds break the marine 

boundary layer and enter the free troposphere. 

Because downslope samples are simultaneously collected 

on Teflon and Nuclepore filters, we can compare the 

collection efficiencies of the two types of filter. Figure 3 

shows a comparison of the 1989-1990 monthly averages for 

so; on Teflon and Nuclepore filters. Both types of filters 

have about the same collection efficiency for so;. 

110 
,_, 1.7 

I.I (•) I.I (b) 

... 

1.4 

... l.J 

... l.l 

. .. 

"" 0.7 

-€ 0.1 Cl) 

::I. o.a 

"" 0.t 

.€ ... Cl) 

:I. 0.7 

... 

1\ O.l 

.... 0.l 

0.1 D 

o.a 

o.s 

... 

O.l 

0.1 

v 0 H ' v 0 ' v 

Month ~fonl.b. 

Fig. 2. Concentrations (μg m·3) of (a) so; and (b) S02, 1989- 1990. Each sample is collected for 1 week. 

:oo 

100 

-

"" 400 

.§ 

ao 

c lOO 

200 

100 

v 0 H 

month V A 

CZ) Teflon c:;::sJ '.\'uclcporc 

Fig. 3. Comparison of so; collection efficiencies of Teflon and 

Nuclepore filters at MLO during 1989-1990. Monthly averages 

(ng m·3) are compared. 

3. O NGOING RESEARCH 

Samples are still being collected continuously using the 

system started in 1985. We are currently analyzing all the 

samples collected since 1985 and doing additional data 

analysis. All data from 1979 to the present will be combined 

to give a 12-yr record of atmospheric particulates and a 6-yr 

record of atmospheric gases at MLO. To obtain more 

TAB LE 1. Mean Concentrations of Several Elements 

During 1987 Clean and Dust Seasons 

Mean 

Element Concentration, ng m·3 Dust/Clean 

Clean Dust Ratio 

Al 23.3 122.3 5.2 

v 0.0186 0.1604 8.6 

Mn 0.37 1.69 4.6 

Na 22.0 49.5 2.3 

Cl 2.4 6.5 2.7 

Br 0.61 0.98 1.6 

information, we also plan to use inductively coupled plasma 

analysis on the samples from 1985 to the present to measure 

additional elements. 

Acknowledgments. Support for the research was supplied in part by 

NSF grant 62632. We also thank the NOAA/CMDL staff at MLO 

for the collection of air filter samples and the staff at Los Alamos 

National Laboratory for assistance with instrumental neutron 

activation analysis. 

REFERENCES 

Bodhaine, B.A., B.G. Mendonca, J.M. Harris, and J.M. Miller, 

Seasonal variations in aerosols and atmospheric transmission at 

Mauna Loa Observatory,]. Geophys. Res., 86, 7395-7398, 198 1. 

Parrington, J.R., The chemistry of background atmospheric particles 

collected at Maun a Loa Observatory, Hawaii, Ph.D. thesis, 

Un iversity of Maryland, 1983. 

Parrington, J.R., W.H. Zoller, and N.K. Aras, Asian dust: Seasonal 

transport to the Hawaiian Islands, Science, 220, 195-197, 1983. 

111 
A Temperature Inversion Climatology for Barrow: 1976-1985 

JONATHAN D. KAHL 

University of Wisconsin, Department of Geosciences, Milwauku, Wisconsin 53201 

1. INTRODUCTION 

The tropospheric temperature inversion is an ubiquitous 

feature of the high-latitude climate. In the Arctic, the 

inversion is a complicated phenomenon involving interactions between surface radiative cooling, subsidence, and 

warm-air advection [Vowinckel and Orvig, 1970; Busch et 

al., 1982). Multiple inversion layers are frequently found in 

Arctic temperature soundings [Belmont, 1957). The 

inversion layer nearest the surface, the low-level temperature 

inversion, is primarily driven by a deficit of solar radiation at 

the earth's surface. The low-level inversion inhibits the 

mixing of surface-level air with air of the overlying "free" 

troposphere and thus plays an important role in the dynamics 

of the Arctic planetary boundary layer. 

The low-level temperature inversion has been linked to 

topics of current interest in Arctic research, including the 

occurrence and transport of Arctic haze [Bridgman et al., 

1989) and the destruction of boundary layer ozone at the 

onset of polar sunrise [Barrie et al., 1988). In addition, 

knowledge of inversion characteristics is needed to model 

the movement of sea ice [Overland, 1985) and to estimate 

the fluxes of heat and moisture through leads and polynyas 

[Barry and Miles, 1988). 

This paper describes the climatological characteristics of 

the low-level temperature inversion at BRW, the site of a 

background atmospheric chemistry monitoring station in 

continuous operation since 1972 [Bodhaine, 1983). The 

results should assist research on current problems in Arctic 

meteorology, air chemistry, and oceanography. 

2. RESULTS 

Twice-daily rawinsonde ascents for 1976-1985 were 

analyzed in this study; only 6.5% of the soundings were 

missing. The rawinsonde data were supplemented with 

3-hourly surface observations to compute cloud-cover 

statistics (Section 2.2). An inversion-detection algoritlun 

was developed to identify low-level inversion characteristics 

objectively. This algorithm is described by Kahl [1990). 

2.1. INVERSION CHARACTERISTICS 

Three fundamental inversion characteristics are determined for each sounding throughout the 10-yr analysis 

period: height of inversion base, inversion depth, and 

temperature difference across the inversion. The monthly 

distributions of these characteristics are shown in Figures 

1-3. The data are displayed as "box and whisker" diagrams, 

showing the 5th, 25th, 50th (median), 75th, and 95th 

percentiles (thus 90% of the distribution occurs within the 

extent of the whiskers). Numerical summaries of these 

distributions are given in Table 1. 

During the entire 1976-1985 analysis period, the inversion 

base (Figure 1) was situated at the surface over 39% of the 

time at BRW. The inversion was surface-based at least 25% 

of the time during all months but May, June, and September. 

Surface-based inversions occurred more than half the time 

from November through February. Perhaps more interesting 

is the observation that the inversion was frequently based 

above the surface, even during the winter months. Thus, the 

commonly-used term "surface temperature inversion" is a 

misnomer; "low-level temperature inversion" 1s more 

appropriate. 

Monthly distributions of inversion depth for 1976-1985 

are shown in Figure 2. The median depths were greatest in 

March (-850 m) and smallest in September (-250 m). The 

largest monthly variations in inversion depth occurred during 

the coldest months, November through April, with interquartile ranges of 700-800 m. 

Distributions of temperature difference across the 

inversion for 1976-1985 are shown in Figure 3. These data 

exhibit the same seasonal trends as do inversion depth data 

(Figure 2); a median maximum of 11 'C occurred in February 

and a minimum of 2'C in September. 

2.2. RELATIONSHIP OF THE INVERSION TO CLOUD 

COVER 

The inversion characteristics shown in Figures 1-3 do not 

exhibit a simple annual cycle of deeper, surface-based 

inversions in the coldest months followed by shallower, 

elevated inversions in the warmer months. Rather, a 

temporary plateau is reached in the months of June, July, and 

August whereby the median inversion base retreats toward 

the surface, while the median depth and temperature 

difference decrease less rapidly or even remain constant. 

This pattern is investigated further by comparing the median 

inversion depths with mean cloud cover statistics. The cloud 

cover is analyzed in the form of total sky cover (including 

fog) recorded in the 3-hourly surface observations for the 

period 1976-1985. 

The sky-cover data are shown in Figure 4, along with the 

median inversion depths of Figure 2. The most notable 

feature of the sky-cover climatology is the extreme cloudiness at the Alaskan coastal stations, particularly durin ~ 

May-October, having mean values in excess of 70%. This is 

primarily due to the prevailing easterly wind off the Beaufort 

Sea. Also prominent is the plateau from May to July when 

the springtime sky-cover increase is halted at about 75%. In 

August the increase resumes, and the sky cover reaches a 

peak of about 90% in September. The inversion depth 

closely follows the armual cycle of clear-sky percentages; the 

middle-year plateau in inversion depth corresponds to the 

plateau in the sky-cover climatology. 

112 
2000 - ·1 T-1 

ll~I llT or INVERSION DASE 1800 - UARROI\', Al.ASKA: 1976- 1985 

1600 i 

.... I ~00 -

I <.> I ... 1200 -

~ 

I "' 1000 - Q 

:::> 

... 800 -

~ i= 

_, 

... 600 -

400 

200 

M A M s 0 N D 

llONTll 

Fig. I. Monthly distributions of height of inversion base at BRW, 

1976-1985. The box and whisker diagrams show upper and lower 

quartiles (lop and bottom of box), median (asterisk), and 5th and 

95th percentiles (outer extent of whiskers). 

2000 "l 

I NVERSI ON OEPTll 

1800 - BARROll'. ALA SKA 1976- 1985 

1600 

I~ 00 -

I -

"' l 1200 

j ~ ~ i: I 0011 -

o~l .... 

.., 

Q 800 

~~D~rJ 600 -

400 I 

I ! I 200 

0 ,------r-, - T 

r M A M J J A s 0 N D 

HONTll 

Fig. 2. Monthly distributions of inve rsion depth at BRW, 1976-

1985. The box and whisker diagrams show upper and lower 

quartiles (top and bottom of box), median (asterisk), and 5th and 

95th percentiles (outer extent of whiskers). 

3. DISCUSSION 

The climatic features of inversions and cloud cover along 

the Alaskan Arctic coast are part of the complex interactions 

between radiative forcings [Maykut and Church, 1973), 

synoptic activity [Serreze and Barry , 1988), and sea-ice 

dynamics [Barry et al., 1979]. During the winter, the l arge 

radiation deficit at the surface fosters the development and 

maintenance of strong inversions, primarily based on the 

surface. Synoptic activity in the Alaskan Arctic basin at that 

time is dominated by anticyclones, and the coastal waters are 

covered with continuous land-fast ice. 

24 

22 TEMPERAT URE Dirr. ACR OSS I NVERSION 

p 20 

BARROW, ALA SKA: 1976- 198 5 

"' 18 - u 

z 16 -

"' 

~~~ "' "' 14 I ... i ... I I 

Q 12 

~~ "' 10 "' 

~~ ~~8~ :::> 

... 8 ... 

"' "' 6 .... ! ! )I 

"' ... 2 8 ! ! ' 

0 = : 

F' M A M A s 0 N 0 

llONTll 

Fig. 3. Monthly distributions of temperature difference across the 

inversion at BRW, 1976-1985. The box and whisker diagrams show 

upper and lower quartiles (top and bottom of box), median 

(asterisk), and 5th and 95th percentiles (outer extent of whiskers). 

100 1000 

90 900 

80 800 2 / ~ 70 , 700 :c 

.. "' .._ 

"' > "' 00 - tiOO 0 

0 

u z 

0 

>- 50 - 500 c;; .. "' "' "' > 40 400 :!:: 

30 - BARROI 300 

BARTER ISLAND ... 20 ~- 200 

F II .. s 0 H 

llONTll 

Fig. 4. Mean monthly sky cover, in percent, from 3-hourly surface 

observations at BRW and at Barter Island, Alaska. Also shown is 

the monthly median inversion depth from Figure 2 and approximate 

breakup and formation dates of the land-fast sea ice [a fter Barry ti 

al., 1979]. 

Beginning in March, the radiation deficit is reduced by a 

rapid increase in solar irradiance combined with a relatively 

high frequency of clear skies. Throughout the spring the 

surface temperature rises, accelerating ablation and decreasing the thermal stability near the surface. A mixed layer 

forms above the surface, elevating the inversion. At this 

time the cloudiness also increases, weakening the inversion 

through the increased longwave radiative flux to the surface. 

Synoptic activity continues to be dominated by anticyclones, 

while the coastal ice remains stable. The increase in 

cloudiness and decrease in inversion depth co7ltinues until 

May when a plateau is reached. 

113 
TABLE 1. Cumulative Frequency Distributions oflnversion Characteristics at BRW, 1976-1985 

Percentile* Jan. Feb. March April May June July August Sept. Oct. Nov. Dec. All 

Height of Inversion Base (m AGL) 

5 0 0 0 0 0 0 0 0 0 0 0 0 0 

10 0 0 0 0 0 0 0 0 0 0 0 0 0 

25 0 0 0 0 Ill 31 0 0 49 0 0 0 0 

50 0 0 44 117 282 187 89 179 382 343 0 0 116 

75 147 169 166 254 521 401 197 420 797 747 216 177 329 

90 326 337 287 401 736 730 452 922 1489 1185 413 331 653 

95 464 485 397 515 916 1076 799 1453 2415 1490 532 471 977 

Inversion Depth (m) 

5 80 82 86 83 68 76 82 63 41 50 58 58 65 

10 150 176 213 126 113 120 114 98 59 71 94 103 100 

25 405 469 525 366 220 215 209 197 111 137 227 311 232 

50 686 79 1 855 668 429 405 410 342 222 277 555 657 492 

75 1032 1183 1212 1066 702 594 601 538 399 538 876 1026 833 

90 1330 1490 1516 1359 941 791 856 782 590 826 1200 1294 1203 

95 1563 1711 1765 1472 1134 935 982 976 737 1058 1354 1459 1395 

Temperature Difference Across In version ("CJ 

5 1.0 1.0 1.2 0.7 0.4 0.3 0.3 0.2 0.1 0.3 0.4 0.4 0.3 

10 2.6 3.4 3.5 1.9 0.9 0.7 0.7 0.4 0.3 0.5 I.I 1.4 0.8 

25 6.3 6.7 6.4 3.9 2.7 2.0 2.5 1.5 0.8 1.0 3.3 4.0 2.6 

50 10.3 10.8 9.1 6.8 5.4 4.7 5.2 3.5 1.8 2.5 6.0 8.1 5.8 

75 14.4 14.2 12.1 9.8 8.5 7.4 8.3 6.0 3.8 4.7 9.8 11.7 9.9 

90 18.8 17.4 15.3 12.4 I I.I 10.3 11.9 9.1 6.2 7.3 12.6 14.7 13.6 

95 21.5 19.2 17.3 13.9 13.5 11.5 13 .5 12.1 7.7 10.3 14.6 16.7 15.9 

*The value corresponding to the nth percentile indicates that n% of the distribution is less than or equal to that value. 

In describing the radiation climate of BRW, Maykut, and 

Church ( 1973] note that 70% of the annual radiative flux to 

the -surface occurs as longwave radiation. This is consistent 

with the observed relationship between inversion depth and 

cloud cover (Figure 4). However, the surface radiation 

budget fails to explain the late summer peak in cloud cover 

and the associated weakening of the inversion. A more 

likely explanation is that the apparent equilibrium between 

the mean radiative and cloud forcings, established in May, 

breaks down in July with the breakup of the land-fast sea ice 

[Barry et al., 1979). Large areas of open water, combined 

with prevailing easterly winds [Harris and Herbert, 1980] 

and the summer peak in the frequency of cyclone activity 

[Serreze and Barry, 1988). result in nearly continuous sky 

cover from August until October. Longwave radiation from 

this enhanced cloud cover further weakens the inversion 

until October when the coastal waters begin to freeze. 

4. REFERENCES 

Barrie, L.A., J.W. Bottenheim, R.C. Schnell, P.J. Crutzen, and R.A. 

Rasmussen, Ozone destruction and photochemical reactions at 

polar sunrise in the lower Arctic a1mosphere, Nature, 334, 

138-141, 1988. 

Barry, R.G., and M.W. Miles, Lead patterns in Arctic sea ice from 

remote sensing data: Characteristics, controls and almospheric 

interactions, Ex1ended Abstracts Volwne, Second Conference on 

Polar Meteorology and Oceanography, Madison, WI, March 29-31, 

1988, pp. 40-43, American Meteorological Society, Boston, 1988. 

Barry, R.G., R.E. Moritz, and J.C. Rogers, The fast ice regimes of the 

Beaufort and Chukchi Sea coasts, Alaska, Cold Regions Sci. 

Technol., J, 129-152, 1979. 

Belmont, A.D., Lower tropospheric inversions at ice island T-3, J. 

Atmos. Terr. Phys., Special Supplement, Part I, 215-284, 1957. 

Bodhaine, B.A., Aerosol measurements at four background sites, J. 

Geophys. Res., 88, 10,753-10,768, 1983. 

Bridgman, H., R.C. Schnell, J.D. Kahl, G.A. Herbert, and E. Joranger, 

A major haze event near Point Burow., Alaska during AGASP-II, 

2-3 April 1986: Analysis of probable source regions and transport 

pathways, Atmos. Environ., 23, 2537-2549, 1989. 

Busch, N., U. Ebel, H. Kraus, and E. Schaller, The structure of the 

subpolar inversion-capped ABL, Arch. Meteorol. Geophy:r. 

Bioc/im .. 3JA, 1-18, 1982. 

Harris, J.M., and G.A. Herbert, Carbon dioxide, condensation nuclei 

and wind climatology of the Barrow GMCC Observatory 

(1973-1979), NOAA Data Report ERL ARL-2, Air Resources 

Laboratory, Silver Spring, MD, 112 pp., 1980. 

Kahl, J.D., Characteristics of the low-level temperature along the 

Alaskan Arctic coast, J. Climatol., in press, 1990. 

Maykut, G.A., and P.E. Church, Radiation climate of Barrow, Alaska, 

1962-1966, J. Appl. Meteorol., 12, 620-628, 1973. 

Overland, J.E., Atmospheric boundary layer structure and drag 

coefficients over sea ice, J. Geophys Res., 90, 9029-9049, 1985.• 

Serreze, M.C., and R.G. Barry, Synoptic activity in the Arctic basin, 

1979-1985,J. Climate, J, 1276-1295, 1988. 

Vowinckel, E., and S. Orvig, The climate of the North Polar Basin, in 

World Survey of Climatology, Vol. 14: Climates of the Polar 

Regions, edited by S. Orvig, pp. 129-226, Elsevier, Amsterdam, 

1970. 

114 
The Global Precipitation Chemistry Project 

WILLIAM C. KEENE AND JAMES N. GALLOWAY 

University of Virginia, Charlottesville, Virginia 22903 

GENE E. LIKENS 

Institute of Ecosystem Studies, Cary Arboretum, Millbrook, New York 12545 

JOHN M. MILLER 

NOAA, Air Resources Laboratory, Silver Spring, Maryland 20910 

1. INTRODUCTION 

Anthropogenic emissions of S02 and NO. 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: (I) What was 

the composition of precipitation prior to the advent of 

fossil-fuel combustion, and (2) To what degree does the 

long-distance transport of sulfur and nitrogen species 

influence the composition of the remote troposphere? The 

GPCP was initiated in 1979 to address these questions. 

Principal objectives are to measure the chemical composition 

of precipitation in remote areas of the world and to 

determine major processes controlling measured 

compos1t1on. Earlier reports of the GPCP compare the 

composition of precipitation in remote and impacted regions 

[Galloway et al., 1982, 1984, 1987); quantify the importance 

of, evaluate sources of, and intercompare measurement 

techniques for carboxylic acids in the atmosphere [Keene et 

al., 1983, 1989; Keene and Galloway , 1984a, b, 1985, 1986, 

198 8); evaluate the cycling of amine compounds in the 

atmosphere [Gorzelska and Galloway, 1990]; assess factors 

controlling the chemical composition of precipitation at 

remote locations [Jickells et al., 1982; Church et al., 1982; 

Galloway and Gaudry, 1984; Dayan et al., 1985; Likens et 

al., 1987; Keene et al., 1990); and present objective methods 

for differentiating seasalt and non-seasalt constituents in 

marine precipitation and aerosols [Keene et al., 1986; 

Hawley et al., 1988]. This report summarizes results of a 

study made to determine processes controlling the composition of precipitation on Amsterdam Island, Indian Ocean, and 

describes experiments conducted with formicine ants in 

order to arrive at a preliminary estimate of the contribution 

of formic acid by the ants to the global formic acid budget of 

the atmosphere. On-going research is briefly summarized. 

2. MATERIALS AND METHODS 

Samples of precipitation were collected by event in 

scrupulously washed polyethylene containers. Immediately 

after collection, pH was measured, samples were treated with 

CHC1

3 to prevent biological activity, and aliquots were sent 

to the University of Virgirlia 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. 

Three colonies each from three different species of 

formicine ants were collected in central Virginia. Each 

colony was placed in a 61 x 20 x 20 cm Teflon-lined 

plexiglass enclosure swept with 16 L min·1 of ambient air. 

Formic acid (HCOOH) in the inlet and outlet air streams was 

sampled with mist chambers, and concentrations were 

measured by ion chromatography. Emissions of HCOOH 

from each colony were determined from differences in 

HCOOH concentrations in the inlet and outlet air streams. 

To assess the representativeness of data generated by this 

procedure, emissions were also measured in the field by 

inverting the enclosure over an undisturbed ant colony and 

operating it as above. The colony was subsequently 

collected and placed inside the enclosure. Emissions from 

the enclosed colony were then measured. An average 

detection limit of 3.8 nmol per colony hour (0.0054 nmol per 

ant hour) was calculated from 10 replicate 1-h enclosure 

blanks. 

3. RESULTS AND DISCUSSION 

3.1. PROCESSES CONTROLLING THE CHEMICAL 

COMPOSITION OF PRECIPITATION ON AMSTERDAM 

ISLAND, INDIAN OCEAN 

Samples of precipitation were collected on an event basis 

at Amsterdam Island in the central Indian Ocean from May 

1980 through January 1987 [Moody et al., 1990]. The 

quality-assured data set correspondCd to 179 samples 

analyzed for major inorganic ions, and a subset of 142 

samples analyzed for major carboxylic species. Back 

trajectories and 222Rn data were used to identify source 

regions for air masses generating precipitation at the site. 

The technique of cluster analysis was applied to determine 

the influence of source region and trarisport velocity on the 

chemical composition of precipitation. The most important 

source regions in terms of ion deposition were Madagascar 

and/or southeast Africa, and the oceanic region north and 

east of Amsterdam Island. Several processes were found to 

influence variability in the chemical composition of 

prec1p1tation. These include seasonality in the source 

strength of biogenic precursors for non-seasalt so; and 

carboxylic acids, seasonality in continental influences, 

variations in source region driven by daily changes in 

meteorology, and seasonal and interarmual differences in 

transport and removal patterns. Interannual differences in 

non-seasalt so; concentrations, in particular, suggest a 

115 
relationship with changes in large-scale atmospheric 

circulation patterns, defined by the Southern Oscillation 

phenomenon. 

3.2. ATMOSPHERIC FORMIC ACID FROM FORMICINE 

ANTS 

Comparisons between em1ss1ons of HCOOH from 

undistrubed and enclosed colonies of formicine ants indicate 

that representative data were generated by the experimental 

technique [Donoghue, 1990). The average rate of HCOOH 

emission from the nine colonies tested was 0.43 ± 0.16 nmol 

per ant hour. A marked diel periodicity was observed; 70% 

of the HCOOH was emitted during the day between 0900 

and 1700 LST. The emission rate exhibited a significant 

positive correlation with temperature. Assuming instantaneous vertical mixing to 1000 m, a 1-day atmospheric 

lifetime, and population densities reported in the literature, 

we estimate that formicine ants contribute approximately 

4% of ambient HCOOH concentrations during the growing 

season in central Virginia. On the basis of estimated 

source strengths for HCOOH and ant population densities 

from the literature, we estimate that formicine ants 

contribute 24% of HCOOH in the atmosphere over the 

world's continents. 

4. ONGOING RESEARCH 

Research efforts currently under way within the GPCP 

include analysis of a 15-year data record for precipitation 

chemistry at MLO; assessment of processes controlling the 

chemical composition of precipitation at Cape Point, South 

Africa; Torres del Paine, Chile; and Lijiang, China; 

evaluation of linkages between the cycling of sulfur and 

nitrogen in the remote atmosphere; and interpretation of 

atmospheric transport patterns in north central Siberia. 

5. REFERENCES 

Church, T.M., J.N. Galloway, T.D. Jickells, and A.H. Knap, The 

chemistry of western Atlantic precipitation al the mid-Atlantic 

coast and on Bermuda, J. Geophys. Res., 87, 11,013-11,018, 

1982. 

Dayan, U., J.M. Miller, W.C. Keene, and J.N. Galloway, A 

meteorological analysis of precipitation chemistry data from 

Alaska, Atmos. Environ., 19, 651-657, 1985. 

Donoghue, C., Atmospheric formic acid from formicine ants, M. S. 

thesis, University of Virginia, unpublished, 1990. 

Galloway, J.N., and A. Gaudry, The chemistry of precipitation on 

Amsterdam Island, Indian Ocean, Atmos. Environ., 18, 

2649-2656, 1984. 

Galloway, J.N., G.E. Likens, W.C. Keene, and J.M. Miller, The 

composition of precipitation in remote areas of the world, J. 

Geophys. Res., 87, 8771-8786, 1982. 

Galloway, J.N., G.E. Likens, and M.E. Hawley, Acid precipitation: 

Natural versus anthropogenic compounds, Science, 226, 

829-830, 1984. 

Galloway, J.N., D. Zhao, J. Xiong, and G.E. Likens, Acid rain: 

China, United States and a remote area, Science, 236, 

1559-1562, 1987. 

Gon.elska, K., and J. N. Galloway, Amine nitrogen in the 

atmospheric environment over the North Atlantic Ocean, Global 

Biogtochem. Cycles, submillcd, 1990. 

Hawley, M.E., J.N. Galloway, and W.C. Keene, Standard error 

calculations for non-sea-salt constituents in marine precipitation, 

Water Air Soil Pollut., 42, 87-102, 1988. 

Jickells, T.C., A.H. Knap, T.M. Church, J.N. Galloway, and J.M. 

Miller, Acid precipitation on Bennuda, Nature, 297, 55-56, 

1982. 

Keene, W.C., and J.N. Galloway, A note on acid rain in an Arnn.on 

rainforest, Tel/us, 368, 137-138, 1984a. 

Keene, W.C., and J.N. Galloway, Organic acidity in precipitation of 

North America, Atmos. Environ., 18, 2491-2497, 1984b. 

Keene, W.C., and J.N. Galloway, Gran's titrations: Inherent errors 

in measuring the acidity of precipitation, Atmo.r. Environ., 19, 

199-202, 1985. 

Keene, W.C., and J.N. Galloway, Considerations regarding sources 

for formic and acetic acids in the troposphere, J. Geophys. Re.r., 

91, 14,466-14,474, 1986. 

Keene, W.C., and J.N. Galloway, The biogeochemical cycling of 

formic and acetic acids through the troposphere: An overview 

of current understanding, Tel/us, 408, 322-334, 1988. 

Keene, W.C., J.N. Galloway, and D.H. Holden, Jr., Measurement 

of weak organic acidity in precipitation from remote areas of 

the world, J. Geophys. Res., 88, 5122-5130, 1983. 

Keene, W.C., A.A.P. Pszenny, J.N. Galloway, and M.E. Hawley, 

' Sea-salt corrections and interpretation of constituent ratios in 

marine precipitation, J. Geophys. Res., 91, 6647-6658, 1986. 

Keene, W.C., R.W. Talbot, M.O. Andreae, K. Beecher, H. 

Berresheim, M. Castro, J.C. Farmer, J.N. Galloway, M.R. 

Hoffmann, S.-M. Li, J.R. Maben, J.W. Munger, R.B. Norton, 

A.A.P. Pszenny, H. Puxbaum, H. Westberg, and W. 

Winiwarter, An intercomparison of measurement syllems for 

· vapor and particulate phase concentrations of formic and 

acetic acids, J. Geophys. Res., 94, 6457-6471, 1989. 

Keene, W.C., G. Wu, R.S. Artz, J.N. Galloway, 1. Liu, J.M. 

Harris, and J.M. Miller, Processes controlling the chemical 

composition of precipitation at a remote temperate continental 

site in south-central China, Proc. of the International 

Conferences on Global and Regional Environmental 

Atmospheric Chemistry, edited by C.S. Kiang, Beijing, PRC, in 

press, 1990. 

Likens, G.E., W.C. Keene, J.M. Miller, and J.N. Galloway, The 

chemistry of precipitation from a remote, terrestrial site in 

Australia, J. Geophys. Res., 92, 13,299-13,314, 1987. 

Moody, J.L., A.A.P. Pszenny, A. Gaudry, J.N. Galloway, W.C. 

116 

Keene, and G. Polian, Precipitation composition and its 

variability in the southern Indian Ocean, 1980-1987. J. 

Geophys. Ru., submitted, 1990. 
Radioactivity in the Surface Air at BRW, MLO, SMO, and SPO 

RICHARD LARSEN AND COLIN SANDERSON 

U.S. Department of Energy, Environmental Measurements Laboratory, New York, New York 10014-3621 

1. NTRODUCTION 

Air filter samples are routinely collected by CMDL 

personnel at BRW, MLO, SMO, and SPO for EML's Surface 

Air Sampling Program (SASP). The primary objective of 

this program is to study the temporal and spatial distribution 

of specific natural and anthropogenic radionuclides in the 

surface air. Of the radionuclides that are analyzed by 

gamma-ray spectrometry, only the naturally occurring 

radioisotopes 7Be and 21opb are still readily measured in 

most of the filter samples. 7Be (half-life 53.2 days) is 

produced by cosmic-ray interactions in the upper troposphere 

and the stratosphere. 210Pb (half-life 2 1 years) is a decay 

product of 222Rn, which is a natural radioisotope emitted 

from soils. Because of their distinctly different source 

regions, these radioisotopes serve as tracers for upper and 

lower tropospheric sources and tr!IJlsport processes. 

2. MATERIALS AND METii ODS 

High-volume air filter samples are continuously collected 

on approximately a weekly basis using Microdon filter 

material. The air samplers move - 1700 m3 of air per day 

through a 20-cm diameter filter. 

The weekly filter samples collected at BRW and MLO are 

analyzed by compressing a section of each filter into a 1-2 

cm3 cylinder, which is analyzed by gamma-ray spectrometry 

using a high-purity germanium (HPGe) detector with a 

1.5-cm diameter well. For each site, one-half of each of the 

weekly filter samples are added together to form a monthly 

TABLE 1. Monthly Surface Air Concentrations of Radionuclides at BRW, MLO, SMO, and SPO During 1989 

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

BRW Gamma (cpm m·3) • • • • • < 0.01 <0.01 <0.0 1 <0.01 <0.01 <0.0 1 <0.0 1 

MLO Gamma (cpm m·3) <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.0 1 < 0.01 < 0.01 <0.01 <0.01 <0.01 

SMO Gamma (cpm m·3) <0.01 <0.01 <0.01 <0.01 <0.01 <0.0 1 <0.01 <0.0 1 <0.01 <0.01 <0.0 1 <0.01 

SPO Gamma (cpm m·3) <0.0 1 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.0 1 <0.01 • <0.01 <0.01 

BRW 7Be (mBq m·3) • • • • • 0.2 0.5 0.6 0.6 I.I 1.4 1.5 

MLO 7Be (mBq m·3) 5.8 6.1 6.7 5.4 4.9 5.7 4.2 5.0 5.4 3.3 5.9 5.1 

SMO 7Be (mBq m·3) 1.7 1.8 1.7 1.3 1.9 2.3 3.0 3.7 3.5 1.9 I. 9 2.1 

SPO 7Be (mBq m·3) 3.6 4.7 3.2t 1.4 l.4t 1.6 1.8 1.7 1.5 • 1.2 3.0 

BRW 95zr (μBq m·3) • • • • • <4.8 <2.2 <4.5 <2.2 <6.4 <4.0 <3 .0 

MLO 95zr (μBq m·3) <10.6 <8.7 <20.5 <4.9 <12.0 <7.2 <4.8 <7.0 <5.7 <9.4 <4.1 <I I.I 

SMO 95zr (μBq m·3) <6.5 <6.2 <2.9 <3.7 <3.1 <10.3 <2.9 <3.1 <2.6 <2.0 <7.3 <1.6 

SPO 95zr (μBq m·3) <4.0 <70.8 <67.5 <31.0 <48.4 <8.6 <I I.I <14.9 <I 8.4 • 33.1 <10.7 

BRW t37Cs (μBq m·3) • • • • <1.0 <0.8 <1.2 <0.7 <1.2 <0.9 <0.9 

MLO 1J1cs (μBq m·

3) <4.5 <3.5 <3.0 <2.2 <3.7 <2.5 <2.1 <2.1 <2.1 <2.2 <1.3 <4.0 

SMO t37Cs (μBq m·3) <1 .6 <2. 1 <1.4 <1.1 <1.3 <3.2 <1.0 <0.9 <I.I <1.6 <1.7 <1.8 

SPO t37cs (μBq m·3) <1.7 <1.8 <1.3 <1.4 <1.7 <0.8 <1.4 <2.0 <2.5 • <4.1 <1.7 

BRW 144Ce (μBq m·3) • • • • • <3.3 <2.8 <5.1 <2.0 <5.0 <2.9 <3.1 

MLO 144Ce (μBq m·3) <18.4 <14.l <13.4 <7.6 <15.7 <10.7 <7.5 <8.6 <8.6 <9.2 <5.3 <16.6 

SMO 144Ce (μBq m·3) <6.4 <6.1 <5.5 <4.5 <5.2 <15.2 <4.6 <4.8 <5.1 <2.5 <8.6 <2.4 

SPO 144Ce (μBq m·3) <6.9 <11.5 <8.2 <8.6 <10.2 <3.9 <6.8 <7.4 <11.4 • <16.4 <7.6 

BRW 210pb (mBq m·3) • • • • • 0.02 0.06 0.10 0.10 0.25 0.87 0.97 

MLO 210pb (mBq m·3) 0.15 0.25 0.34 0.28 0.31 0.26 0.27 0.19 0.27 0.16 0.29 0.20 

SMO 210pb (mBq m·3) • • • • • • • • • • • 

SPO 210pb (mBq m·3) 0.03 0.05 0.01 O.D3 0.01 0.04 0.03 0.02t 0.03 • <0.0 1 0.04 

*No data 

tUncertainty is between 20% and 100%; uncertainty for all other concentrations is <20%. 

117 
composite sample. These composite samples are compressed 

into a 45-cm3 plastic planchet, and are routinely analyzed for 

several gamma-ray-emitting radionuclides using either HPGe 

n-type low-energy coaxial or Ge(Li) or HPGe p-type coaxial 

high-resolution germanium detectors. Detailed information 

on SASP is periodically published [Larsen and Sanderson, 

1990]. 

3. RESULTS 

The results of the analyses of several radionuclides and 

the total gamma-ray activities for the monthly composite 

samples from filters collected at BRW, MLO, SMO, and 

SPO during 1989 are reported in Table 1. The total 

gamma-ray activities are reported in units of counts per 

minute (cpm) per standard cubic meter (15'C, 1 atm) of 

sampled air. The surface air concentrations of 7Be and 210Pb 

are reported in millibecquerels (mBq) per _s.tandard cubic 

meter of air, and 95Zr, 137Cs, and 144Ce are reported in 

microbecquerels (μBq) per standard cubic meter of air. The 

concentrations are reported as corrected for radioactive 

decay to the midpoint of the month of collection. The results 

of the analyses on the weekly samples from BRW and MLO 

are being prepared for publication as an EML report. 

4. DISCUSSION 

There were no armounced atmospheric nuclear weapom 

tests or other reported significant releases of radioactive 

materials into the atmosphere during 1989, and the concentrations of fission products such as 95Zr, 137Cs, and '44Ce were at 

or below the lower limits of detection for the analytical and 

sampling techniques that we currently use to measure them. 

Monthly mean concentrations continue to show a seasonal 

cycle for 7Be at all CMDL sites, and a seasonal cycle for 21opb 

at BRW and MLO. 

Acknowledgme111. We thank the NOAA/CMDL s1aff at BRW, MLO, 

SMO, and SPO for the collection of air filter samples for the SASP. 

5. REFERENCE 

Larsen, R.J., and C.G. Sanderson, Annual report of the surface air 

sampling program, EML-524, 120 pp., U.S. Department of Energy 

Environmental Measurements Laboratory, New York, 1990. 

118 
Total Nitrate Variations at Mauna Loa 

G. LEE AND B. J. HUEBERT 

University of Rhode Island, Graduate School of Oceanography, Na"aganselt, Rhode Island 02882-1197 

1. INTRODUCTION 

Much of the NO and N02 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, the total nitrate concentration (nitric acid vapor and 

aerosol nitrate) represents a fair estimate of the total 

odd-nitrogen concentration [Galasyn et al.,1987a, b; 

Robin.son and Harris, 1987]. 

With support from NSF, we have measured nitrate 

concentrations at MLO for several years to help identify the 

important sources of odd-nitrogen compounds in remote 

parts of the globe. Since August 1988, in collaboration with 

the MLO staff, we have been measuring total nitrate every 

night. 

2. MATERIALS AND METHODS 

Initially, one nylon filter was exposed each night from 

2000 to 0800 LST to collect the total nitrate. During the 

summers of 1988 and 1989, a Teflon/nylon filter pack 

method, which entails the separate collection and measurement of nitric acid vapor and nitrate aerosol, was used. We 

began using this method exclusively in March 1990 in an 

attempt to ascertain the causes of the spring and summer 

increases in total nitrate from changes in its composition 

with time. 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. SHORT-TERM VARIATIONS 

Figure 1 shows the total nitrate vanatton from August 

1988 to July 1990. All samples measured at MLO have been 

included. No period of steady (less than a 50% change) 

concentration lasting more than 10 days was measured. 

Total nitrate concentrations fluctuated unpredictably from 

day to day. Some of the short-term decreases in total nitrate 

appear, however, to be related to approaching frontal zones 

and rain storms. It is most likely, also, that some of the 

positive spikes in the total nitrate reflect local island sources. 

Generally, the magnitude of total nitrate short-term variation 

during spring and summer is much larger than that of fall and 

winter. Extensive synoptic and dynamic analyses are 

required to examine closely the details of these short-term 

variations. 

900 

BOO 

700 ...... 

> 

c.. 

sBOO 

c 500 .g 

~ 400 " ... 

<J 

c 300 0 

u 

200 

100 

0 

200 300 400 500 600 

,~; 700 800 900 1000 

Aug. ea Dec.88 Apr.89 Aug.89 Dec.89 Apr.90 Aug.00 

Fig. 1. Total nitrate versus time at MLO, August 1988-July 

1990. 

3.2. LONGER-TERM VARIATIONS 

The most apparent feature of the longer-term variations in 

total nitrate at MLO is the concentration increase during 

spring and summer months (Figure 2). This annual variation 

has been observed every year. Total nitrate in 1989 was 

higher and more variable than that of 1990. It is unknown 

whether the causes of the springtime high concentrations are 

fundamentally different from those in summer. In 1990 a 

slight concentration dip is evident in May. Because samples 

were not measured during June 1989, the details of spring 

and summer total nitrate variations are still unclear. 

300 

...... 

~ 250 

sc 

.g 200 .. 

... 

" u 150 

f f 

<J 

~ c 

~ 0 

f f 

u 

.... 

0 100 

z 

r ~ f f 50 r ~ r ~ 0..,...-.-0-:-r-r-r--r-"T'"-r-.-r-,--,--.,......,.-.-.--,--,---,--.--..-,.--.-.+ Aug. 88 Dec.88 Apr. 89 Aug.89 Dec.'89 Apr.Ila Aug.90 

Fig. 2. Monthly mean total nitrate concentrati ons at MLO with 

standard deviations. 

119 
The averages and standard deviations of total nitrate 

concentration in winter are small. Compared with data 

obtained in past years, the large concentrations of total 

nitrate in December 1989, which lasted about a week, were 

unusual. 

4. ONGOING RESEARCH 

We are continuing our nightly sampling from the tower 

with the help of the MLO staff. Although equipment 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 and 

confirm both the frequency and source of high nitrate events 

during the next year . 

5. REFERENCES 

Galasyn, J.F., K.L. Tschudy, and BJ. Huebert, Seasonal and diurnal 

variability of nitric acid vapor and ionic aerosol 1pecie1 in the 

remote free troposphere at Mauna Loa, Hawaii, J. Geophys. Res., 

92, 3105-3133, 1987a. 

Galasyn, J.F., K.L. Tschudy, and BJ. Huebert, Authors' Reply to 

the Comment of Robinson and Harris, /. Geophys. Res., 92, 

14,868, 1987b. 

Robinson, E., and J. Harris, Comment oo "Seasonal and diurnal 

variability of nitric acid vapor and ionic aerosol species in the 

remote free troposphere at Mauna Loa, Hawaii," by Galasyn, 

Tschudy, & Huebert, J. Geophys. Res., 92, 14,865-14,867, 1987. 

120 
Seasonal and Latitudinal Trends in the 13C/I2C Ratio of Methane 

PAUL QUAY, STAGG ICING, JOHN STUTSMAN, AND DAVID WILBUR 

University of Washington, School of Oceanography WB-10, Seattle, Washington 98195 

1. INTRODUCTION 

The isotopic composition of methane (CH4) can be used to 

distinguish between various CH4 sources [e.g., Stevens and 

Engelkemeir, 1988; Wahlen et al., 1989; Quay et al., 1990]. 

CH4 released from natural gas and biomass burning sources 

has a distinctly higher 13C/12C ratio than does CH4 

microbially produced in anoxic environments like rice 

paddies, wetlands, and ruminants. Our research at the 

CMDL sites has focused on measuring the seasonal and 

latitudinal trends in the llC/12C ratio of CH4 . We intend to 

use the measured trends in 13CH4 to constrain the spatial and 

temporal variability in the release rate of CH4 from wetlands 

and biomass burning sources. Results of these measurements 

are discussed in Quay et al. [1990). 

2. SAMPLING AND ANALYSIS 

We have been collecting CH4 samples for isotopic 

analysis from the CMDL sites at BRW and MLO, and at a 

site on the Washington coast (48.N, 126'W) since 1987. In 

1989 we initiated a similar sampling program at SMO. We 

also have had samples collected at Cape Grim (41 'S, 144'E) 

by CSIRO. We ship a pre-evacuated 35- or 15-L flask to the 

sampling site, where the flask is simply opened, allowed to 

fill to atmospheric pressure, and then returned to our 

laboratory. The CH4 concentration at time of collection is 

provided by CMDL. Air samples are collected approximately biweekly, except at Cape Grim where collection 

is bimonthly. CH4 in the air sample is extracted, purified, 

and combusted to C02 under high vacuum following the 

procedure developed by Stevens and Rust [1982]. The C02 

is measured for its •3C/12C ratio using a Finnigan MAT251 

mass spectrometer. This procedure yields a C02 sample 

volume of -30 μL for mass spectrometric analysis. 

l3C/12C of the atmospheric CH4 is reported relative 

to 13C/12C of a standard (PDB) using the del notation (Ii): 

where sam is the sample and std is the standard. The 

precision of our S13C measurement is about± 0.04%0, based 

on standards analyzed over the last year. 

3. RESULTS AND DISCUSSION 

The results of our llCH4 measurements at our three 

northern hemisphere sampling sites are presented in Figure 

1. The 13CH4 data at BRW and the Olympic Peninsula do 

not show a significant interannual change; at MLO there 

appears to be a slight increase in 13CH4 with time. The 

PT. BARROW 

•47.0r---r--,--,.----,.--,--,.---,.--,--......---.-~~ 

0 

0 

ooo oooo o o 0 oeo 

0 

;5 -47.~ o 0 qr{}o o 0 "" oC19 dlo o o o oo o o<o o o o roc{Jl oo 

0 0 <19 0 

0 

,.... 

0 

ef3., -49.0 

u .., 

0 

00 

0 

a 

0 

0 

-oo.o'---:-:---'--..__.._ _ _,__..___,_ _ _._ _ _,____.'---1...--.J 

- - 1987 - OCT - ~ 1988 AA OCT - ~ 1 -989 OCT 

OLYMPIC PN. 

-40.Sr---r--,.--,.---,.--,.--,.----.-....,---r---.r---.---, 

c:Q ·47.0 

0 

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x"' oo6' o u -47.4 00 0 

.... ':x:P 0 0 0 

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cf. 

..._, -47.8 

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0 0 

0 0 Oo 

0 

0 

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0 0 0 

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oQioo o o 

0 0 

·48.2 .___.__......__.___.__.....__.___.._ _ _..__.....___. _ _.__J 

J~ N'R 1 9"~7 OCI - N'R 19"~8 OCT J~ N'R 1~89 •OCT 

MAUNA LOA 

-40.a .----,.--,.--,.--,.--,--...---.--.--....---.r---.---, 

c:o 

0 

"" -47.0 .,; 

> 

... ::::: -41.2 

u 

... 

0 

C) -47,4 

0 

~ u -o.o !:! 

c:; 

-o -47.a 

0 

o ocf 

0 0 

00 0 0 0 

0 

0 

0 

.O '---'--......__.___,_ _ _,__..___,_ _ _._ _ _,____. _ _,__J 

- - 198- 7 OCT - ~ 1988 AA OCT - ~ 1989 - OCT 

Fig. I. Time series for the Ii 13C of atmospheric CH4 at three 

clean-air sites in the northern hemisphere. 

121 
-46.5.-----~---,- -.....----.---~---.----~-----. 

co 

0 

P. 

~ ... -47 .0 

::c 

u 

._ 

0 

c; 

0 

~ -47.5 

;;;> 

CG Ml OP PB 

I 

-48.0'---~--_J,_-~----'--~~--'---~-_J 

concentration, we estimate a kinetic isotope effect during 

CH4 oxidation (i.e., k1:ifk1:J of 0.993 [Quay et al., 1990]. 

Our measured global mean average 1> 11C of -47.2%0, when 

coupled with a kinetic fractional effect of 0.993, yields a 

value of -53 .3%o for the Ii 13C of the global CH4 source. An 

estimate of the CH4 released from biomass burning can be 

derived from the li13C of the global source [e.g. Stevens and 

Engelk£meir, 1988]. We estimate that biomass burning 

contributes - 11 % of the total CH4 source strength or - 60 Tg 

yr' based on a total source strength of -550 Tg yr1 [Quay et 

al., 1990]. 

4. REFERENCES 

1.60 1.65 1. 70 

CH4 ( ppmv) 

1.75 1.80 

Fig. 2. Relationship between the mean annual Ii l3C and concentration of atmospheric CH4 at Cape Grim (CG; 41'S, 144'E), MLO 

(ML; 19'N, 155'W), Olympic Peninsula (OP; 48'W, 126'W), and 

BRW (PB; 71'N, 156'W). 

annual mean IJCH4 values increase southward from an 

annual mean value of -47.6%0 at BRW to -47.0Yoo at Cape 

Grim, Figure 2. There is an inverse correlation between 

annual mean CH4 concentration and 13CH4 (Figure 2). This 

trend is expected because of the isotopic fractionation during 

OH oxidation of CH4 when 12CH4 is oxidized at a slightly 

faster rate than 13CH4 [e.g., Davidson et al., 1987). On the 

basis of the inverse correlation b etween 13CH4 and CH4 

Davidson, J.A., C. A. Cantrell, S.C. Tyler, R.E. Shetter, R.J. 

Cicerone, and J.G. Calvert, Carbon kinetic isotope effect in the 

reaction ofCH4 with OH,J. Geophys. Res., 92, 2195-2199, 1987. 

Quay, P.D., S.L. King, J. Stutsman, D.O. Wilbur, L.P. Steele, I. 

Fung, R.H. Gammon, T.A. Brown, G.W. Farwell, P.M. Grootes, 

and F.H. Schmidt, Carbon isotopic composition of atmospheric 

CH4 : Fossil and biomass burning source strengths, Global 

Biogeochem. Cycles, in press, 1990. 

Stevens, C.M., and A. Engelkemeir, Stable carbon isotopic 

composition of methane from some natural 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. 

Wahlen, M., N. Tanaka, R. Henry, B. Deck, J. Zeglen, J.S. Vogel, J. 

122 

Southon, A. Shemish, R. Fairbanks, and W. Broecker, Carbon-14 

in methane sources and in atmospheric methane: Contribution 

from fossil carbon, Science, 245, 286-290, 1989. 
Aerosol Constituents at American Samoa, November 1989 

DEt-.'NIS L. SAVOIE Al'\D JOSEPH M. PROSPERO 

University of Miami, Rosenstiel School of Marine and Atmospheric Science, Division of Marine and Atmospheric Chemistry 

Miami, Florida 33149-1098 

RICHARD ARL\10TO A~D ROBERT A. DUCE 

University of Rhode Island, Graduate School of Oceanography, Center for Atmospheric Chemistry Studies 

Narragansett, Rhode Island 02882-1197 

1. INTRODUCTION 

A major goal of our cooperative work at SMO is to define 

more rigorously the sources, atmospheric pathways, and 

fluxes of particulate nitrogen and sulfur species in the remote 

marine atmosphere. Toward this end, we continue to collect 

weekly bulk aerosol samples at SMO where past studies 

[e.g., Arimoto et al., 1987] indicate that the transport of soil 

material and pollutants from continental sources is extremely 

low. In addition, daily aerosol samples were collected 

throughout November 1989, as part of our support for the 

First Survey Flight of the NASA, GLOBE. The objective of 

GLOBE is to assess the feasibility of a space-based lidar 

system that could provide vertical profiles of winds over a 

substantial portion of the earth. Our task in this endeavor 

was to place the period of the flight within a climatological 

framework by comparing the November 1989 results with 

those from our long-term record. We also used this 

opportunity to make our first measurements of ammonium 

and to investigate further the relationship between MSA and 

nss sulfate at remote sites. 

As with our normal weekly samples, the daily samples 

were collected from onshore winds by drawing air through 

20 x 25 cm Whatrnan 41 filters at a flow rate of 1.1 m3 min-1. 

Nitrate, sulfate, and MSA in aqueous extracts of the filters 

were determined by ion chromatography, ammonium by 

automated colorimetry, and sodium by flame atomic 

absorption at the University of Miami; aluminum 

concentrations were measured by neutron activation analysis 

at the University of Rhode Island. Mineral aerosol was 

estimated from aluminum, which constitutes about 8% of the 

mineral aerosol mass. Nss sulfate was estimated as total 

sulfate minus sodium times 0.2517, the sulfate to sodium 

mass ratio in seawater. 

2. MEAN CONCENTRATIONS 

Samples included in this study were collected from 

October 31 through November 30, 1989. The wind was 

out-of-sector more than 80% of the time during the 

collection of the last sample of the series and therefore the 

results from that sample are not considered here. For the 

other samples, the nitrate, sulfate, sodium, and MSA 

concentrations in the samples were all well above their 

detection limits; concentrations on the filters were at least 10 

times higher than in the blanks, and the net concentrations 

(total-blank) were always at least 50 times higher than the 

standard deviation of the blank. In contrast, the ammonium 

and aluminum blanks accounted for a major fraction of the 

total concentrations of these species in most of the samples. 

Gross ammonium concentrations in the samples were usually 

only a factor of 2 higher than the blanks, and most net 

concentrations were only factors of 3-4 higher than the 

standard deviation of the blank. For aluminum, the gross 

sample concentrations were frequently within the range of 

the blanks and were never more than a factor of 3 higher 

than the average blank. Because the reported sample 

concentrations are based on the net sample concentration 

(gross minus average blank), calculated negative 

concentrations frequently result when the atmospheric 

concentrations are extremely low, as is the case for 

aluminum. Though the results clearly attest to the very low 

concentrations of ammonium and mineral dust at the site. the 

high relative errors for these constituents make it difficult to 

assess the real day-to-day variations in their concentrations. 

Four of the samples were collected over 2-day (as 

opposed to I-day) periods. In calculating the statistical 

parameters for the data set, we assigned each day of these 

2-day periods the same set of concentrations, i.e., the mean 

concentrations for the 2-day period. The statistics calculated 

on this basis are presented in Table 1 along with other 

comparative data. The levels of most of the various 

constituents are roughly equivalent to those from the 

complete long-term data set and to those from all previous 

Novembers. Moreover, the similarity of the SMO and 

Rarotonga (21 '15'S, 159'45'W) data indicate that the SMO 

concentrations may apply to a broad region of the tropical 

South Pacific. There are, however, some temporal and 

geographical differences that are significant and may prove 

to be important. 

The mean nitrate concentration at SMO during November 

1989 is about 35% higher than the long-term (1983-1987) 

November mean and 55% higher than the overall 1983-1987 

mean. Although the various means at Rarotonga exhibit a 

similar trend, the differences are not as dramatic. Also, 

while the overall long-term means at SMO and Rarotonga 

are esentially identical, the November 1989 mean at SMO is 

about 25% higher than that at Rarotonga. 

The mean nss sulfate concentration during November 

1989 is identical to the 1983-1987 November mean and also 

does not differ significantly from the overall 1983-1987 

mean. As with nitrate, the November 1989 mean nss sulfate 

at SMO is significantly higher than that at Rarotonga by 

about 30%. 

123 
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°' c 

~ 

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0 

... 

.. 

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AMERICAN SAMOA 

150 

100 

50 

0 

-50 

0.4'1 2 5 211 

0.3 

0.2 

0.1 

0.8 

0.5 

o.• 

0.3 

0.2 

0.1 

JO 

25 

20 

15 

10 

5 

60 

50 

•O 

30 

20 

10 

0 

-1 

15 

10 

5 

0+1,1.~~ 

-1 2 5 8 11 1• 17 20 23 28 29 

Sample Start Date: November 1989 

Fig. 1. Daily-average concentrations of chemical species in 

a1mospheric particulates at SMO during November 1989. 

M 

-I 

8 

bl) 

::t 

-

< {/) 

~ 

0.07 

0.06 

0.05 

0.04 

0.03 

0.02 

0.01 

• ramimc Ia. (11N11-1eea) 

• Samoa (11N13-19N) 

0 Samoa (NOY., 11N19) & 

C Rarotonp (NOY., 11N19) 

N•93, r 2-o.ee 

G.o. Wean RaUo: 

0.0801-t:_0.00.1 

c 

• • • 

0 0 

0.00 +-~--.----.-..--~-.....---.-....--__.... 

0.0 0.2 0.4 0.6 0.8 1.0 

NSS Sul!ate {μg m-3) 

Fig. 2. MSA versus nss sulfate at SMO, Fanning Island, and 

Rarotonga for various time periods. 

Ac/c.nowltdgnunts. We thank T. Snowdon, R. Nees, Huang F., 

Huang T., and M. Izaguirre (all of the University of Miami) and J.D. 

Cullen (University of Rhode Island) for their technical assistance. 

We also thank C. Farmer and E. Wilson-Godinet (NOAA/CMDLJ 

SMO) for maintaining and operating our sampling systems. We 

gratefully acknowledge the cooperation of B. Mendonca and 

NOAA/CMDL Boulder for allowing us to continue our program at 

SMO. This work was supported under NASA contract NAG 8-621. 

5. REFERENCES 

Arimoto, R., R.A. Duce, B.J. Ray, A.O. Hewiu, and J. Williams, Trace 

elements in the atmosphere of American Samoa: Concmtratioos and 

deposition to the tropical South Pacific, J . Gtophys. Res., 92, 

8465-8479, 1987. 

Prospero, J.M., and D.L Savoie, Effect of continental sources on nitrate 

concentrations over the Pacific Ocean, NaJwt, 339, 687-689, 1989. 

Prospero, J.M., M. Uematsu, and D.L Savoie, Mineral aerosol transport 

to the Pacific Ocean, in Chemical Oceanography, vol. JO, edited by 

J.P. Riley, R. Chester, and R.A. Duce, pp. 188-218, Academic, 

Londoo, 1989. 

Quinn, P.K., R.J. Charlson, and T.S. Bates, Simultaneous observationJ 

of ammonia in the atmosphere and ocean, NaJwt, 335, 336-338, 

1988. 

Saltzman, E.S., D.L Savoie, J.M. Prospero, and R.G. Zika, Atmospheric 

methancsulfonic acid and non-aeasalt sulfate at Fanning and 

American Samoa, Gtophys. Rt.s. u11., 12, 437-440, 1985. 

Saltzman, E.S., D.L Savoie, J.M. Prospero, and R.G. Zill, 

Methanesulfonic acid and non-sea-salt sulfate in Pacific air. Regional 

and seasonal varia1ions, J. Atmos. Chem., 4, 227-24-0, 1986. 

Savoie, D.L., J.M. Prospero, and E.S. Saltzman, Nitrate, non-seasalt 

sulfate and methanesulfonate over the Pacific Ocean, in Chemical 

Oceanography, vol. JO, edited by J.P. Riley, R. Chester, and R.A. 

Duce, pp. 219-250, Academic, London, 1989a. 

Savoie, D.L., J.M. Prospero, J.T. Merrill, and M. Uematsu, Nitrate in the 

atmospheric boundary layer of the tiopical South Pacific: 

Implications regarding sources and transport, J. Almm-. Chem. 8, 

391-415, i 989b. 

Savoie, D.L., J.M. Prospero, R. Larsen, and E.S. Saltzman, Nitrogen and 

sulfur species in aerosols at Mawson, An1.arctica, and their 

relationship to natural radioouclides, J. Atmos. Chem., in preparation, 

1990. 

124 
Update on the 0-Ring Bias as Determined from MLO 

Precipitation Chemistry Samples 

G. J. STENSLAND 

Illinois Stale Water Survey, Atmospheric Science Division, Champaign, Illinois 61820 

In a cooperative study with the CMDL staff at MLO, 

special precipitation samples were collected to evaluate the 

bias (contamination) introduced into the chemical results by 

the 0 -ring in the lid of the collection/shipping container. 

This 0 -ring bias may be important for other data sets 

because the majority of precipitation chemistry networks in 

the United States have used this collection/shipping 

container since 1978. Sample collection in this cooperative 

project began in February 1984, and by December 1987, 73 

sample sets had been collected. A summary of the 0-ring 

effect on pH for these first 73 samples was presented in the 

Geophysical Monitoring for Climatic Change. No. 17: 

Summary Report 1988 [Elkins and Rosson, 1989]. 

Sample collection continued through October 1989. The 

complete sample set (117 samples) has now been analyzed 

and quality assured. The research in progress consists of a 

final interpretation of these 117 sample sets to determine the 

0-ring bias on pH, so;, NO;, ~.CA++,MG+, NA•, 

and K•. Results will be compared with results from 

measurements obtained at a Pennsylvania site and a 

Baltimore site that should be published next year. 

REFERENCE 

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

Climatic Change, No. 17: Summary Report 1988, 130 pp., 

NOAA Air Resources Laboratory, Boulder, CO, 1989. 

125 
Trends of the Carbon Isotopic Composition of Atmospheric 

Methane in the Southern Hemisphere 

C. M. STEVENS AND A. ENGELKEMEIR 

Argonne National Laboratory, Chemical Technology Division, Argonne, lllinois 60439 

The Jong-term trend of the stable carbon isotopic 

composition of atmospheric CH4 in the southern hemisphere 

was investigated using air samples collected at SMO. The 

objective of this program is to apply the results to understanding the causes of the increasing global concentration of 

atmospheric CH4 • The interpretations of the results to date, 

including those of the only air samples collected in 1989, 

were summarized by Stevens and Engelk.meir [1989). These 

results show 13CH4 increasing in both hemispheres, but with 

a greater rate of increase in the southern hemisphere. 

Increasing fluxes of isotopically ..hea'ly C2H4 ·from biomass 

burning in the southern hemisphere during the past decade 

are calculated to be 3-4 Tg yr2 (fg = 1012 g), which is 50% 

of the increasing concentration of atmospheric CH4 and 

hence a major cause of atmospheric CH4 increase. A 

detailed analysis of the isotopic results will be given in a 

forthcoming paper. 

REFERENCES 

Stevens, C.M., and A. Engelkemeir, Trends of the carbon isotopic 

composition of atmospheric methane, in Geophysical Monitoring 

for Climatic Change, No. 17: Summary Report 1988, edited by J. 

W. Elkins, pp. 131-132 NOAA Air Resources Laboratory, 

Boulder, CO, 1989. 

126 
Bromine and Surface Ozone Atmospheric Chemistry at Barrow, Alaska, 

During Spring 1989 

W. T. STuRGES A:"\'D R. C. SCll:"\'ELL 

Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, Colorado 80309-0216 

S. J. 0LT:vtA:"\'S 

NOAA, Climate Monitoring and Diagnostics l..Aboratory, Boulder, Colorado 80303-3328 

S. LA~DSBERGER 

University of Illin ois, Department of Nuclear Engineering, Urbana, Illinois 61801 

S.-M. LI 

Atmospheric Environment Service, Downsview, Ontario MJIJ 5T4, Canada 

1. l:'\-rRODUCll0:--1 

Surface ozone and particulate and gaseous bromine were 

measured at BRW during March and April 1989 lo examine 

the causes of surface ozone destrnction during the Arctic 

spring. A simple photochemical experiment was pcrfom1ed to 

investigate the rate of particulate bromine formation. 

2. METllODOLOGY 

Sam pies were collected during 12-h periods, with changeover at about 1000 and 2220 LST. Particulate bromine was 

collected on PTFE or Nuclcpore membranes. Organic halogen 

gases were collected by absorption in Tcnax GC chromatography absorbent in 4-mm-insidc-diamctcr glass tubes. 

Inorganic bromine gases were collected on KOH-impregnated 

cellulose filters downstream of either a PTFE filter or an MgO 

denuder and filter combination. Ozone data, consisting of 

consecutive hourly average concentrations, were obtained 

from routine measurements at BRW by CMDL staff, as were 

meteorological data. 

PTFE filter samples were analyzed by neutron activation 

analysis (NAA). Nucleporc filters were water extracted for 

bromide ion analysis by ion chromatography. Tenax tubes 

were thermally desorbcd into a gas chromatograph, and 

organic halogenated species were measured with an electron 

capture detector. 

A simple experiment was performed at BRW to determine 

if filterable bromine formation could be induced in the 

ambient nighttime atmosphere by illumination with Jongwavelcngth UV (actinic) light. Air drawn into the building 

was split through two identical Pyrex glass tube chambers, one 

of which was surrounded by actinic fluorescent tubes that 

simulate the actinic spectrum of midday solar radiation at 

BRW at that time of year. The other chamber was blacked out 

and acted as a control for the illuminated chamber results. 

Both chambers were connected to filter packs. Experiments 

were conducted during the hours of total darkness and only 

when the air was flowing off the Arctic Ocean so that the key 

bromine species would be present, but not at times when 

ozone was already almost completely removed so as to 

prohibit further reactions. 

3. RESULTS A:-\D DISCUSSIO:-\ 

The surface ozone record for the study period is shown in 

the top panel of Figure I. Several large negative excursions in 

ozone arc numbered 1-5. Episodes with concentrations more 

typical of a well-mixed and nondcpleted troposphere are 

identified by the letters A-C. These high-ozone periods 

occurred during either incursions of Pacific air or downslope 

air off the Brooks Range mountains. There was no consistent 

evidence for an impact on ozone during airflow from local 

combustion sources, taken as occurring when winds were from 

215-320' (a Jess stringent definition than normal of the 

clean-air sector is required in considering ozone chemistry). 

Particulate total bromine (f-Br) amounts measured by NAA 

are shown in the center panel of Figure 1. The major ozone 

depiction events occurred during Limes of elevated f-Br, 

although the f-Br record is incomplete during several of these 

events due to difficulties in access to the station. 

Bromoform concentrations are plotted in the lower panel of 

Figure 1. Dibromochloromcthanc and bromodichloromcthanc 

concentrations (not shown in the figure) were strongly 

correlated to bromoform, but at about an order of magnitude 

lower levels [Sturges et al., 1990a], suggesting a common 

origin, which we believe to be Arctic sea ice microalgae 

[Sturges et al., 1990b]. Bromoform peaked at about the same 

time as f-Br, approximately coinciding with ozone depletion 

events I and 2. 

Inorganic gaseous bromine is discussed by Sturges et al. 

( l 990a]. It was found to be a relatively minor component of 

total atmospheric bromine, and was not strongly correlated to 

ozone depletion. 

Figure 2 shows the amount of f-Br formed in the illuminated chamber in excess of that measured in the (dark) control 

chamber. The gradient of the line implies a rate of formation 

off-Br of 7.9 ng Br m·3 min· 1; i.e., it would take on the order 

of minutes to form the ambient f-Br concentrations observed 

in this study. A study of air mass trajectories and satellite 

127 
';'40 

.0 

Cl. 

0.30 ...._ 

~ 20 

0 

N 

0 10 

4 

2 

,-.... 

.., 300 I 

E 

O> 

c 

200 .._ 

~ 

CD 

Q) 

100 -0 

:::J 

0 

:;: 'lfll?O ~ 

0 0 

a.. ,-..20-+-~~~~~~~~~~~~~~~~~--:e:t._-+­

> -Cl. 

Cl. ...._ 

E 

~10 

0 

-0 

E 

0 

~ 

CD 

••••• Night sample 

G0BB£l Day sample 

O-t-,....,..-r-T""T....,.e!IB-.......,.-.-..,........-.-..,.............,.eg.-,-.-.,.--,-.--.--r-r--.--r-+ 

70 80 90 100 

Day of Year (1989) 

Fig. I. Ozone, particulate bromine (f-Br), and bromoform gu measurements from March JI to April 10 (LST), 1989, at BRW. Open 1ymboh 

are day samples; filled symbols are night samples. In the top panel, numbers 1-5 refer to ozone depiction cvenu, and lettcn A-C refer to 

high-ozone periods. 

images during this period [Sturges et al., 1990a] indicated 

that ozone depletion was associated with transport from open 

leads in the Arctic Ocean, at most 1 or 2 days upwind. This 

also indicates that the reaction rates of bromine-ozone 

photochemistry are rapid. 

Such rapid photochemistry disagTees with a model of 

ozone destruction involving gas-phase photolysis of 

bromoform [Barrie et al., 1988]. Can the two sets of 

observations be reconciled? One clue comes from a 

comparison of the NAA and IC results (Figure 3). Total 

bromine was invariably higher than bromide ion, and the 

greatest discrepancy was at night. We propose that organic 

bromine-rich particles undergo reactions to produce more 

readily photolyzable forms of bromine with an accompanying conversion to inorganic bromine in the particle. 

Independent evidence for the existence of such particles has 

been recently shown (P. J. Sheridan, personal communication, AGASP ill mission). Leads may be a possible source 

of these particles. 

4. CONCLUSIONS 

Dramatic surface ozone destruction events at BRW in 

the spring are accompanied by elevated levels of filterable 

bromine (f-Br) and organic bromine gases. Photochemical 

experiments showed a rapid formation potential for f-Br in 

the Arctic spring atmosphere; there is also evidence that 

ozone depletion is a rapid process. Simple gas-phase 

photolysis of bromoform is evidently too slow to account 

for such fast reactions, but there is evidence that organic 

128 
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30 

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'"O 

Q) 20 E 

'-

0 

'-

en 10 

Q) 

-0 

::J 

u 

- 0 '-

0 

CL 

10+--.--.--.--,--,--,-·-,--,--,-~~~~~~~~~ -+ 

0 1 2 3 

Residence Time (min) 

Fig. 2. Excess f-Br fonned in the photochemical chamber. The 

error bars arc anal ytical uncertainty (1 sigma). 

bromines in the particulate phase may take part in fast 

photolytic processes. 

ck wledg~nts. We acknowledge support and assistance from 

the National Research Council, NOAA/CMDL, the BRW staff, and 

the North Slope Borough. 

REFERENCES 

Barrie, L.A., J.W. Bottenheim, R.C. Schnell, P.J. Crutzcn, and R.A. 

40 ~INAA 

IC 

30 ,--.. 

... 

I 

E 

O> 

c 20 

-Q) 

c 

E 

0 10 I.. 

CD 

4-~~~~~~-.-~~~~-.-~~~~ ....... ~~~-+ 

85 90 95 100 

Day of Year (1989) 

Fig. 3. Comparison of analyses of total elemental bromine by NAA 

and of bromide ion by IC. Open symbols are day samples, filled 

symbols are night samples. 

Rasmussen, Ozone destruction and photochemical reactions al polar 

sunrise in the lower Arctic atmosphere, Nature, 334, 138-141, 

1988. 

Sturges, W.T., R.C. Schnell, S. Landsberger, S.J. Oltmans, J.M. 

Harris, and S.-M. Li, Chemical and meteorological influences on 

surface ozone destruction at Barrow, Alaska, during spring 1989, 

Atmos. Environ., submitted, 1990a. 

Sturges, W.T., C.W. Sullivan, R.C. Schnell, L.E. Heidt, and W.H. 

129 

Pollack, Bromine production by Antarctic ice algae: The source of 

ozone-depleting bromine radicals in the polar troposphere?, 

Nature, submitted, 1990b. 
USGS Barrow Observatory 

JACK TOWNSHEND 

U.S. Geological Survey, College Observatory, Fairbanlcs, Alaska 99775-5160 

The USGS Barrow observatory is the northernmost of 

this agency's 12 continuously recording, digital magnetic 

observatories. As such, it serves as a singularly important 

site in a global network of observing stations whose 

combined data define the planetary magnetic field and 

track its secular change. Ground stations such as that at 

Barrow are controls for field modeling by harmonic 

analysis, essential reference stations for airborne and 

satellite surveys, and absolute calibration locations for 

field survey instrumentation. The observatory is operated 

from the USGS College Observatory at the University of 

Alaska in Fairbanks, as a satellite station. Staff scientists 

from the College Observatory visit the site bimonthly to 

make absolute observations, perform routine equipment 

maintenance, and retrieve data on magnetic tape. Staff 

from NOAA CMDL make weekly visits to the site to 

check equipment operation and occasionally perform 

emergency service when problems occur and a staff 

person is not available from the College Observatory to 

make repairs. 

The primary equipment used to acquire the magnetic 

data is an EDA FM-lOOBR Triaxial fluxgate magnetometer, 

an EDA PPM-105 proton free-precession magnetometer, an 

observatory magnetometer interface system, and several 

pier-mounted instruments for absolute control of observations. Data are retrieved by telephone periodically through 

a computer modem by the USGS office in Golden, 

Colorado. 

A seismograph is operated on site in a vault 6.1 m 

beneath the ground surface. Access to the vault is down a 

ladder through a 76.2-cm-diameter vertical tunnel. The 

present seismic program is operated in cooperation with the 

Geophysical Institute at the University of Alaska, Fairbanks. 

The USGS Barrow observatory has been in continuous 

operation since 1949. 

130 
Radon from Distant Continents Detected at the Mauna Loa Observatory 

S. WHITTLESTONE 

Australian Nuclear Science and Technology Organization, PMB J, Menai, NSIV, 2037 Australia 

1. INTRODUCTION 

Radon is widely used as a tracer for air masses that have 

passed over land within the last few days, because radon is 

an inert gas unaffected by chemical interactions in transit 

and because land emits about 100 times more radon per 

square meter than does the ocean [Wilkening and Clements, 

1975). 

Previous continuous observations of maritime radon have 

been at sea level [Lambert et al., 1970; Whittlestone, 1985a; 

Downey et al., 1989; Pereira et al., 1988). At a station on 

the coast at sea level, the direct contribution of local land to 

the radon concentration in onshore winds is negligible. 

Events in which radon is transported from distant continents 

are clearly defined. For example, at Macquarie Island, about 

2000 km south of Australia in the Southern Ocean, radon 

concentrations are generally below 100 mBq m·3 but can rise 

to more than 1000 mBq m·3 when the air is from Australia 

[Downey et al., 1989). Air mass trajectory calculations 

confirmed the continental origin of the air at times of 

enhanced radon concentrations. Radon measurements at 

such sites provide evidence of continental contamination of 

baseline air samples, an indication of dilution of the 

continental air during its trajectory, and accurate timing of 

air mass transport for assessment of air transport models. 

MLO is located on the north-northeast slope of the Mauna 

Loa volcano at an altitude of 3397 m. This is above the 

trade wind inversion at some times and below it at others. 

Air influenced by the island is most likely to reach the 

observatory when sun warms the mountain, causing 

convective "upslope" winds. Radon measurements at this 

site could certainly provide evidence of contamination of 

baseline air, but it was not clear prior to this study whether 

the knowledge gained would contribute significantly to that 

obtained from several other parameters already used at MLO 

to characterize the air mass. Some preliminary measurements by Hutter et al. [1989] have shown that there is a 

substantial difference between the radon concentrations 

during episodes when the wind is from the island (upslope 

winds) compared with concentrations in free-tropospheric 

air. 

Only long-term observations could determine the 

concentrations in the boundary layer, in the free troposphere, 

or from the island under a range of air mass transport 

conditions. This study presents preliminary data from 

continuous measurement of radon at MLO during AugustDecember 1989. Meteorological data were correlated with 

the radon concentrations. A number of particular events 

were singled out to demonstrate the range of radon concentrations from local and distant sources. 

2. INSTRUMENTATION 

The radon detector was modeled on that described by 

Whittlestone [1985b). The sensitivity was 0.189 counts s·l 

for a concentration of 1 Bq m·3. A 30% statistical error from 

a 1-h count was obtained at a concentration of 15 mBq m·3. 

The background count rate of the detector was difficult lo 

evaluate. An upper limit was set by the median of the 10 

lowest concentrations measured during the 5-month period, 

that is 30 mBq m·3. The detector response time was 90 

minutes to 50% of maximum. 

3. RESULTS 

Figure 1 shows five typical summer days in August, 

having a strong diurnal cycle in all parameters. The 

maximum radon and particle concentrations occurred during 

periods of upslope (northerly) winds. A high dew point 

during these periods confirms the presence of moist 

boundary layer air. The initial impression from Figure 1, 

that radon is strongly correlated with particles, does not hold 

in general. On August 28, there was a strong radon signal, 

but few particles. This most likely arose because the radon 

source was broadly distributed, whereas particles generally 

come from human habitations. The upslope winds inevitably 

brought radon, but brought many particles only when the 

trajectory was over a town or some other source of particles. 

A more detailed analysis of data for the whole month of 

August showed that radon levels were low even for moist air, 

except when the wind was upslope, bringing radon from the 

island. Such radon concentrations indicated, therefore, that 

the air in both the free troposphere and the boundary layer 

had not contacted land for a period long compared with the 

4-day half-life of radon. 

In November, the weather conditions were different, 

having predominantly southerly local winds (Figure 2) and 

low dewpoint. The radon levels were much higher, having 

peaks up to 700 mBq m·3 on a background of 250 mBq m·3, 

compared with peaks of about 250 mBq m·

3 on a background 

of 70 mBq m·3 in August. There was no positive correlation 

with particles, and no systematic increase during upslope 

wind directions. In fact, c lose examination of the data shows 

that the highest radon concentrations generally occurred 

when the air was sampled from the free troposphere, i.e., 

when dewpoint and particle concentrations were lowest. 

Radon concentrations in the boundary layer were low, and 

most of what was measured could be allributed to local 

sources. From the radon measurements, then, it appears that 

air from a distant continent had been mixed into the free 

131 
0 

........... 

.... - 0.. I 

VI .r:. 

0 ·-

20 

10 z E i ....... ol'.--'l'.:!.....i'---'~~c.......~4-....._..._.1!.._1....1.J'---'-L~1....1....:~....L-...l 

z 

0 0 j::: z (.) 

i~ 0 

1-

z 

5 0.. ....... 

(.) 

N 

w 

s 

E 

N 

~ ....... -15 0 

VI • .... ....... _, .. (.)I 

~ ~ 500 <( ....... 

0.. 

:;-- 300 

z 1E 8 <T 200 <( a> 

0:: 5 100 

25 26 27 

OATE 

29 

0 

t:j~ 0.. I 

VI .C 

oz E - .._, :i:: 

z 

0 0 i:: 

~~ :i:: 0:: 

Ci 

20 

10 

17 19 

DATE 

20 

Fig. I. Meteorological data, particle count~, and radon concentrations at MLO in August 1989. 

Fig. 2. Meteorological data, particle counts, and radon concentrations at MLO in November 1989. 

140 E 160 E 

CD 700 hPa 

+ 500 hPa 

180 w 160 w 

Fig. 3. Back trajectory calculations ending at MLO at 0200 on November 19, 1989. 

132 
troposphere and transported to the observatory with 

relatively little mixing to the boundary layer. 

This interpretation of the radon results was confirmed by 

back trajectory calculations. Figure 3 shows a typical 

trajectory for the boundary layer (700 hPa) and the free 

troposphere (500 hPa) for the period shown in Figure 2. 

Symbols are plotted for each day of the trajectory . The 

free-tropospheric air (dashed line) had come fr.om Asia in 

about 5 days. Transport was much slower in the boundary 

layer and had not passed near land during the 10 days before 

reaching the observatory. 

4. CONCLUSIONS 

Radon measured at MLO with a limit of detection of 15 

mBq m-3 has provided unequivocal real-time proof that the 

air contacted land during the few weeks before it reached 

MLO. This applies equally to boundary layer and freetropospheric air. Radon is therefore a valuable addition to 

the other parameters such as wind speed, wind direction, and 

dew point used to characterize the air sampled at MLO. 

The absolute values of the radon concentrations at MLO 

are similar to those of another remote location, Macquarie 

Island, ranging from about 20 to more than 1000 mBq m·3. 

The maximum concentrations of radon in the lower boundary 

layer and the free troposphere are also very similar. This 

indicates that Jong range transport of a non-reactive gas can 

be just as efficient via the free troposphere as transport in the 

boundary layer. 

Aclcnowledgments. The author is grateful 10 CMDL for providing the 

laboratory space and technical support for this work. Particular 

thanks are due to Elmer Robinson for his assistance during installation 

and S. Ryan for his skilled maintenance and operation of the detector. 

5. REFERENCES 

Hutter, A.R .. A.C. George, M.L. Maiello, I.:vt. Fisenne, R.J. Larsen, 

H.L. Beck, and F.C. Wilson, 222Rn, 222Rn progeny and ~n 

progeny as atmospheric tracers of air mass al the :vfauna Loa 

Observatory, 26 pp., Internal report of the Environmental 

Measurements Laboratory, U.S. Department of Energy, New York, 

NY, 1989. 

Downey, A., J.D. Jasper, J. Gras, and S. Whinlestone, Lower 

tropospheric transport over the Southern Ocean, J. Atmos. Chem., 

in press, 1989. 

Lambert, G., G. Polian, and D. Taupin, Existence of periodicity in 

radon concentrations and in the large-scale circulation al lower 

altitudes between 400 and 700 south, J. Geophys. Res., 75, 

2341-2345. 1970. 

Pereira, E.B., A.W. Setzer, and 1.F.A.Cavalcanti, 222Rn in the Antarctic 

Peninsula during 1986, Radial. Pro/. Dosim., 24(14), 85-88, 1988. 

Whiulestone, S., Radon measurements as an aid to the interpretaLion of 

atmospheric monitoring,!. Atmos. Chem., 3, 187-201, 1985a. 

Whittlestone, S., A high sensitivity Rn detector incorporating a particle 

generator, Health Phys., 49 (5), 847-852, 1985b. 

Wilkening, M.11., and W.E. Clements, Radon-222 from the ocean 

surface, J . Geophys. Res., 80, 3828-3831, 1975. 

133 
11. International Activities, 1989 

CMDL co.~tinued cooperative flask air sampling agreements with Australia (Cape Grim), Barbados (Ragged Point), 

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). Sampling was begun in Bermuda in 

cooperation with the AEROCE program. 

P. Tans, J. Peterson, and K. Thoning attended the Third 

International Carbon Dioxide Conference on Analysis and 

Evaluation of Atmospheric C02 Data Present and Past, held 

October 16-20 in Hinterzarten, Federal Republic of Germany. 

P. Tans visited CSIRO, Division of Atmospheric 

Research, in Melbourne, Australia, on June 19-July 22, to 

work with R. Francey on C02 stable isotopes. 

L. Waterman and representatives of the Chevron Shipping 

and Chevron Research Companies met 1n San Francisco to 

discuss the collection of shipboard air samples aboard 

Chevron vessels. Since emphasis will be on investigation of 

continental sources of CH4 , vessel routes near Asia were 

examined. One such route runs between Singapore and 

Hong Kong in the South China Sea. The suitability of the 

route and the vessel will be tested using an NDIR analyzer to 

make continuous measurements of C02 simultaneously with 

flask sampling on the first voyage. It is planned to have the 

flasks shipped via Singapore. 

A public service commendation plaque was presented in 

San Francisco by L. Waterman to Captain M. McGilvary of 

the MV Southland Star to recognize the collection of the 

lOOOth atmospheric sample by the vessel's deck officers. 

Operation Pacific Air was begun in 1986 to collect air 

samples on the ship's route between the U.S. West Coast and 

Auckland, New Zealand. 

L. Waterman visited Palmer Station, operated by NSF, on 

January 10. The regular air sampling site was inspected, and 

a set of samples was collected by a U.S. Navy volunteer. 

Strategies for collecting samples when the wind was coming 

from directions other than the clean air sector and for 

expediting the return of samples to Boulder on both research 

and cruise ship calls were discussed. L. Waterman also 

visited the British Antarctic Survey station on Bird Island, 

South Georgia, on January 26. He made direct contacts with 

the BAS winter-over staff. They were provided with 

instructions on the use of the P3 air sampler and given a 

short-form manual and equipment diagrams. Nine cases of 

flasks accumulated from previous years of unsuccessful 

attempts to initiate the program were returned to Boulder. 

During February, as part of the return trip from Antarctica, 

L. Waterman visited flask sampling sites at Barbados, at the 

West Indies Laboratory (Teague Bay), and at St. Croix (U.S. 

Virgin Islands). A seminar was given for the West I~dies 

Laboratory staff on the flask network C02 and CH4 results. 

Finally, new sites were selected at St. David's Head and 

Southhampton, Bermuda. 

During March, T. Conway participated in the AGASP-III 

project based in Bodo, Norway. One-hundred eighty-six 

flask air samples were collected on six flights in the Arctic. 

134 

The samples were analyzed in Boulder for C02, CH4, and 

CO. G. Herbert also participated in the AGASP-III project. 

He served as operations meteorologist for the Arctic haze 

sampling phase of this program. 

E. Dutton traveled to Kwajalein in the Marshall Islands in 

March to establish a surface radiation monitoring site. He 

presented a paper entitled "An extraordinary site for surface 

radiation budget/satellite ground-truth studies" at the IAMAP 

89 Fifth Scientific Assembly of the International Association 

of Meteorology and Atmospheric Physics, in Reading, 

England, held July 31-August 12. 

The NOAA reference absolute cavity radiometer was 

taken to Ensenada, Mexico, in April by D. Nelson for a 

WMO-sanctioned regional comparison of pyrheliometers. 

The NOAA instrument was one of a contingent of 10 U.S. 

cavity radiometers that participated. While at the comparison, he gave a short presentation on the current status of 

the U.S. Solar Radiation Network and the development and 

operation of the new Eppley automatic solar trackers. 

B. Bodhaine participated in the International Conference 

on Global and Regional Environmental Atmospheric 

Chemistry in Beijing, China, May 2-11, and presented a 

paper entitled "Aerosol monitoring at Mauna Loa 

Observatory." 

As part of U.S.(U.S.S.R. Working Group VIII (Influence 

of Environmental Changes on Climate), B. Bodhaine, J. 

DeLuisi (U.S. Organizer), and D. Gillette participated in the 

First Soviet-American Symposium on Atmospheric Aerosols 

and Climate at the Institute of Experimental Meteorology, in 

Obninsk, U.S.S.R., held August 28-September 1. The 

purpose of this symposium was to formulate recommendations concerning what aerosol measurements should be made 

to help understand the effects of aerosols on climate. The 

meeting was attended by nine American scientists and 

numerous Sov iet scientists. At the symposium, J. DeLuisi 

presented a paper entitled "Aerosol optical thickness 

measurements for climate modeling," and B. Bodhaine 

presented a paper entitled, "Background aerosol measurements at CMDL stations." 

Following the Obninsk symposium, B. Bodhaine and D. 

Gillette traveled to Dushanbe, Tadzhikistan, U.S.S.R., to 

participate in the U.S.S.R./U.S. Desert Aerosol Experiment 

on September 3-9. This experiment was designed to study 

dust storms and desertification in southern U.S.S.R. Nine 

American and many Soviet scientists participated in the 

study. 

At a Geneva meeting held October 19-21, 1988, the Joint 

Scientific Committee Working Group on Radiative Fluxes 

recommended that the World Climate Research Program 

(WCRP) establish a global baseline network of surface 

stations to measure the solar and terrestrial longwave fluxes 

to help meet the requirements for long-term data sets on 

global surface radiation balance components. The mission of 

this network would be to monitor long-term trends in 

radiation fluxes at the surface and to provide validation data 

for satellite determinations of the surface radiation budget. 
The network would consist of 10-20 strategically located sites 

and would take advantage of existing national sites that meet 

established criteria. The WCRP requested J. DeLuisi's 

assistance to organize the network. At the WCRP Workshop 

on Surface Radiation Budget held at Wunburg, Germany, 

October 30-November 3, 1989, a special session, chaired by J. 

DeLuisi, was held to establish the guidelines for a Baseline 

Surface Radiation Network (BSRN). A report containing the 

workshop's recommendations was written and circulated. It 

became the basis of the BSRN plan, which was issued later. 

J. Elkins attended the Intergovernmental Panel on Climate 

Change (IPCC) meeting sponsored by the WMO and the 

United Nations Environment Program in Cambridge, 

Massachusetts, on October 19. He wrote the N20 section for 

the IPCC report and was acknowledged as a contributor to 

Climate Change, The JPCC Scientific AssessmenJ, Cambridge 

University Press, 1990. 

Total ozone and Umkehr observations continued to be made 

with automated Dobson ozone spectrophotometers at the 

CMDL-foreign cooperative stations of Haute Provence, 

France; Lauder, New Zealand; and Perth, Australia. Similar 

observations were made with a manually operated Dobson 

instrument at Huancayo, Peru. 

R. Evans traveled to MLO during the summer to set up a 

program for checking the state of calibration of World 

Standard Dobson Spectrophotometer no. 83 and to calibrate 

Japanese secondary Standard Dobson instrument no. 116. 

During the summer of 1989, R. Grass optically aligned, 

electronically revamped, and calibrated Pretoria, South Africa, 

Dobson instrument no. 89. He also provided training to M. 

Zunkel of the South African Weather Bureau on the operation, 

maintenance, and calibration of Dobson instruments. 

Surface ozone measurements began at a new AEROCE site, 

Mace Head, Ireland. Similar observations continued in 

Barbados and Bermuda. 

In July, B. Mendonca traveled to Budapest, Hungary, at the 

request of the Hungarian Government, to consult with the 

WMO on the development of a background air pollution 

monitoring network for Hungary. In December, he consulted 

with the Costa Rican Government and the WMO in San Jose, 

Costa Rica, about setting up baseline climate observatories. 

At the invitation of the WMO, J. Peterson attended a 

working meeting in Geneva, Switzerland, May 19-26, to 

finalize publication of the World Climate Data Program 

Review of the Global Climate System for 1986-1988. During 

October 20-24, he presented a paper at a meeting on Monitoring and Assessment of Changing Composition of the Troposphere in Sofia, Bulgaria. He traveled to Taipei, Taiwan, to 

present an invited paper at the U .S.-Taiwan Bilateral Workshop on Long-Tenn Air Quality Changes and Their Climatic 

Impact, held November 18-19. 

On February 4-April 20, members of the Nitrous Oxide and 

Halocarbons Group participated in the RITS 1989 cruise 

aboard the NOAA RIV Discoverer traveling across the central 

and eastern Pacific Ocean. The purpose of this international 

expedition was to measure N20, CFC-11, CFC12, CFC-113, 

CH3CC13, and CCJ.. in air and surface sea water, to measure 

N20 at depth, and to collect flask samples for analysis of 

LEAPS gases between Seattle and the edge of the ice cap near 

Antarctica, and return. The cruise was divided into three 

major legs. T. Thompson helped install the equipment on the 

ship before the first leg. J. Butler and B. Halter ran the 

instruments on the first leg from Seattle to Easter Island. B. 

Halter continued on the second leg from Easter Island to 

Tahiti. C. Brunson joined the ship in Tahiti for the third and 

final leg of the cruise back to Seattle. 

135 
12. Publications and Presentations by CMDL Staff, 1989 

Anderson, S.M., A.C. Delany, F.C. Fehsenfeld, P.D. Goldan, C.E. 

Kolb, B.A. Ridley, and L.P. Steele, Status of chemical sensors 

for flux measurements, in Global Tropospheric Chemistry, 

Chemical Fluxes in the Global Atmcsphere, edited by D.H. 

Lenschow and B.B. Hicks, pp. 47-68, National Center for 

Atmospheric Research, Boulder, CO, 1989. 

Andreae, M., A.C. Delany, S. Liu, 1. Logan, L.P. Steele, H. 

Westberg, and R. Zika, Key aspects of species related to global 

biogeochemical cycles, in Global Tropospheric Chemistry, 

Chemical Fluxes in the Global Atmcsphere, edited by D.H. 

Lenschow and B.B. Hicks, pp. 9-29, National Center for 

Atmospheric Research, Boulder, CO, 1989. 

Bodhaine, B.A., Aerosol monitoring at Mauna Loa Observatory, 

paper Gl1-8 presented at the International Conference on Global 

and Regional Environmental Atmospheric Chemistry, Beijing, 

China, May 3-10, 1989. 

Bodhaine, B.A., Background aerosol measurements at GMCC 

stations, paper presented at the First Soviet-American Symposium on Aerosols and Climate, Obninsk, U.S.S.R., August 

28-September 1, 1989. 

Bodhaine, B.A., Barrow surface aerosol: 1976-1986, Atmos. 

Environ., 23, 2357-2369, 1989. 

Bodhaine, B.A., South Pole aerosol measurements, Ant. J. U. S., 24, 

233-235, 1989. 

Bodhaine, B.A., N.C. Ahlquist, and R.C. Schnell, Three-wavelength 

nephelometer suitable for aircraft measurements of background 

aerosol scattering extinction coefficient, paper 3P.20 presented at 

the 1989 Annual Meeting of the American Association for 

Aerosol Research, Reno, NV, October 9-13, 1989. 

Bodhaine, B.A., E.G. Dutton, 1.1. DeLuisi, G.A. Herbert, G.E. 

Shaw, and A.D.A. Hansen, Surfa ce aerosol measurements at 

Barrow during AGASP 11, J. Almos. Chem., 9, 213-224, 1989. 

Bridgman, H.A., R.C. Schnell, G.A. Herbert, B.A. Bodhaine, and 

S.1. Oltmans, Meteorology and haze structure during AGASP 11, 

Part 2, Canadian Arctic flights, 13-16 April 1986, J. Almos. 

Chem., 9, 49-10, 1989. 

Butler, 1.H., and 1.W. Elkins, An automated headspace technique for 

the measurement of N20 in water and sea water, paper presented 

at the Oceanography Society Inaugural Meeting, Monterey, CA, 

August 27-30, 1989. 

Butler, 1.H., 1.W. Elkins, T.M. Thompson, and K.B. Egan, 

Tropospheric and dissolved N20 of the west Pacific and east 

Indian Oceans during the El Nino Southern Oscillation event of 

1987, J. Geophys. Res .. 94(DJ2), 14,865-14,877, 1989. 

Conway, T.1., and L.P. Steele, Carbon dioxide and methane in the 

Arctic atmosphere, J. Atmcs. Chem., 9, 81-99, 1989. 

DeLuisi, 1., Aerosol optical thickness measurements for climate 

modeling, paper presented at the First Soviet-American 

Symposium on Atmospheric Aerosols and Climate, Obninsk, 

U.S.S.R., August 28-September 1, 1989. 

DeLuisi, 1.1., E.G. Dutton, G.L. Koenig, U.U. Longenecker, and P.1. 

Reddy, Zenith-sky cloud detection for automated Dobson 

Umkehr measurements, in Ozone in the Atmosphere, Proceedings, Quadrennial Ozone Symposium 1988 and Tropospheric 

Ozone Workshop, Halkidiki, Greece, edited by R.D. Bojkov and 

P. Fabian, pp. 736-738, A. Deepak, Hampton, VA, 1989. 

DeLuisi, 1.1., D.U. Longenecker, C.L. Mateer, and DJ. Wuebbles, 

An analysis of northern middle-latitude Umkehr measurements 

corrected for stratospheric aerosols for 1979-1986, J. Geophys. 

Res., 94(D7), 9837-9846, 1989. 

Dutton, E.G., 1.1. DeLuisi, and R.D. Cess, An extraordinary site for 

surface radiation budget/satellite ground-truth studies, paper 

presented at the IAMAP 89 Fifth Scientific Assembly of the 

International Association of Meteorology and Atmospheric 

Physics, Reading, England, July 31-August 12, 1989. 

Dutton, E.G., 1.1. DeLuisi, and G. Herbert, Shortwave aerosol 

optical depth measured on board the NOAA WP-3D, AGASP-II, 

April 1986, J. Atmos. Chem., 9, 71-79, 1989. 

Dutton, E.G., R.S. Stone, and 1.1. DeLuisi, South Pole surface 

radiation balance measurements April 1986 to February 1988, 

NOAA Data Rep. ERL ARL-17, 49 pp., NOAA Air Resources 

Laboratory, Boulder, CO, 1989. 

Elkins, 1.W., Nitrous oxide and the orone layer, paper presented at 

the University of Virginia, Department of Environmental 

Sciences, Charlottesville, VA, October 25, 1989. 

Elkins, 1.W., Recent developments and controversies in atmospheric 

trace gas standards, presented at the Center for Analytical 

Chemistry Colloquium Series, NIST, Gaithersburg, MD, October 

24, 1989. 

Elkins, 1.W., Referee's report (ATLAS-WAS stratospheric nitrous 

oxide intercomparison), presented at the NASA Summer Science 

Meeting, Lake Tahoe, CA, July 17, 1989. 

Elkins, 1.W., Sources and sinks for atmospheric nitrous oxide, paper 

presented at NASA Ames Research Center, Moffett Field, CA, 

August 15, 1989. 

Elkins, 1.W., The state of the research for atmospheric nitrous 

oxide, presented at the Intergovernmental Panel for Climatic 

Change (IPCC), Cambridge, MA, October 19, 1989. 

Elkins, 1.W., Techniques for the preparation of gas standards for 

atmospheric CC14, paper presented at the NOAA/ARL Idaho 

Springs Laboratory, Idaho Falls, ID, April 20, 1989. 

Elkins, 1.W., Trends and distributions of atmospheric nitrous oxide, 

presented at the Atmospheric Chemistry Seminar, Harvard 

University, Department of Earth and Planetary Sciences, 

Cambridge, MA, October 20, 1989. 

Elkins, 1.W., and T.M. Thompson, Measurements of nitrous oxide 

(N20, trichlorofluoromethane (CFC-11 ), and dichlorodifluoromethane (CFC-12) at Niwot Ridge, Colorado, since 

1977, paper presented at the Front Range Branch AGU 

Conference, Colorado School of Mines, Golden, CO, February 

12-14, 1989. 

Elkins, 1.W., T.M. Thompson, B .. Hall, K.B. Egan, and J.H. Butler, 

NOAA/GMCC halocarbons and nitrous oxide measurements at 

the South Pole, Alli. J. U.S .. 23(5), 176-177, 1988. 

Evans, R.D., G.L. Koenig, W.D. Komhyr, 1. Eauon, and P. March~. 

Umkehr observations at five automated Dobson 

spectrophotometer stations in 1986 and 1987, in Ozone in the 

Atmcsphere, Proceedings, Qwadrennial Ozone Symposiwn 1988 

and Tropospheric Ozone Workshop, Hallcidilci, Greece, edited by 

R.D. Bojkov and P. Fabian, pp. 151-154, A. Deepak, Hampton, 

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Fiacco, G., W.D. Komhyr, and D. Fui, Is ozone destroyed during 

the Antarctic polar night in the presence of polar stratospheric 

clouds? Nature, 341(6241), 426-427, 1989. 

Franchois, P.R., G. Koenig, R.D. Evans, and W.D. Komhyr, 

Comparison of ECC oronesonde and Umkehr profiles at Boulder, 

Colorado, 1985-1987, and Mauna Loa, Hawaii, 1985-1987, in 

Ozone in the At11Wsphere, Proceedings, Quadre1111ial Ozone 

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Deepak, Hampton, VA, 1989. 

Grass, R.D., and W.D. Komhyr, Traveling standard lamp calibration 

checks of Dobson ozone spectrophotometers during 1985-1987, 

in Ozone in the At11Wsphere, Proceedings, Qwadrennia/ Ozone 

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Hansen, A.D.A., B.A. Bodhaine, T.J. Conway, and J.D. Kahl, 

Long-range transport of combustion plumes acrou the Arctic: 

Preservation of signature ratios of aerosol blaclc carbon, C02, 

136 
and CH4 , paper 4D.3 presented at the 1989 Annual Meeting of 

the American Association for Aerosol Research, Reno, NV, 

October 9-13, 1989. 

Hansen, A.D.A., T.J. Conway, L.P. Steele, B.A. Bodhaine, K.W. 

Thoning, P. Tans, and T. Novakov, Correlations among 

combustion effluent species at Barrow, Alaska: Aerosol black 

carbon, carbon dioxide, and methane, J. Atmos. Chem., 9, 

283-299, 1989. 

Herbert, G.A., J.M. Harris, and B.A. Bodhaine, Atmospheric 

transport during AGASP-II: The Alaskan flights (April 2-10, 

1986), Atmos. Environ., 23(11), 2521-2535, 1989. 

Herbert, G.A., R.C. Schnell, H.A. Bridgman, B.A. Bodhaine, S.J. 

Oltmans, and G.E. Shaw, Meteorology and haze structure during 

AGASP-II, Part 1, Alaskan Arctic flights, 2-10 April 1986, J. 

Atmos. Chem., 9, 17-48, 1989. 

Kahl, J.D., J.M. Harris, G.A. Herbert, and M.P. Olson, lntercomparison of three long-range trajectory models applied to Arctic 

haze, Tel/us, 4lb, 524-536, 1989. 

Kolb, C.E., F.C. Fehsenfeld, L.P. Steele, and P.O. Goldan, Flux 

measurement program plan, in Global Tropospheric Chemistry, 

Chemical Fluxes in the Global Atmosphere, edited by D.H. 

Lenschow and B.B. Hicks, pp. 69-82, National Center for 

Atmospheric Research, Boulder, CO, 1989. 

Komhyr,W.D., R.D. Grass, R.D. Evans, and R.K. Leonard, Results 

of international Dobson spectrophotometer and Brewer 

spectrometer intercomparisons, Arosa, Switzerland, 1986, in 

Ozone in the Atmosphere, Proceedings, Quadrennial Ozone 

Symposium 1988 and Tropospheric Ozone Work.shop, Halkidiki, 

Greece, edited by R.D. Bojkov and P. Fabian, pp. 776-779, .A. 

Deepak, Hampton, VA, 1989. 

Komhyr, W.D., R.D. Grass, and R.K. Leonard, Calibration of 

primary standard Dobson spectrophotometer no. 83 and total 

ozone trends at Mauna Loa Observatory, Hawaii, and American 

Samoa, South Pacific, in Ozone in the Atmosphere, Proceedings, 

Quadrennial Ozone Symposium 1988 and Tropospheric Ozone 

\Vorkshop, /lalkidiki, Greece, edited by R.D. Bojkov nnd P. 

Fabian, pp. 85-87, A. Deepak, Hampton, VA, 1989. 

Komhyr, W.D., R.D. Grass, and R.K. Leonard, Dobson 

spectrophotometer 83: A standard for total ozone measurements, 

1962-1987, J. Geophys. Res., 94(D7), 9847-9861, 1989. 

Komhyr, W.D., R.D. Grass, P.J. Reitelbach, S.E. Kuester, P.R. 

Franchois, and M.L. Fanning, Total ozone, ozone vertical 

distributions, and stratospheric temperature at South Pole, 

Antarctica, in 1986 and 1987, J. Geophys. Res., 94(09), 

11,429-11,436, 1989. 

Komhyr, W.D., T.B. Harris, L.S. Waterman, J.F.S. Chin, and K.W. 

Thoning, Atmospheric carbon dioxide at Mauna Loa Observatory, I, NOAA Global Monitoring for Climatic Change 

measurements with a nondispersive infrared analyzer, 

1974-1985, J. Geophys. Res., 94, 8533-8547, 1989. 

Komhyr, W.D., I.A. Lathrop, V.N. Arbuzova, V.V. Khattatov, P.G. 

Nureyev, V.V. Rudakov, and 1.V. Zamyshleyev, ECC 

ozonesonde observations at Mirny, Antarctica in 1988, NOAA 

Data Rep. ERL ARL-19, 125 pp., NOAA Air Resources 

Laboratory, Silver Spring, MD, 1989. 

Komhyr, W.D., J.A. Lathrop, R.W. Poston, and T.O. Mullen, ECC 

ozonesonde observations at South Pole, Antarctica, during 1988, 

NOAA Data Rep. ERL ARL-18, 277 pp., NOAA Air Resources 

Laboratory, Silver Spring, MD, 1989. 

Komhyr, W.D., S.J. Oltmans, P.R. Franchois, W.F. Evans, and W.A. 

Matthews, The lati-tudinal distribution of ozone to 35 km 

altitude from ECC ozonesonde observations, Ozone in the 

Atmosphere, Proceedings, Quadrennial Ozone Symposium 1988 

and Tropospheric Ozone Work.shop, edited by R.D. Bojkov and 

P. Fabian, pp. 147-150, A. Deepak, Hampton, VA. 1989. 

Komhyr, W.D., S.J. Oltmans, R.D. Grass, P.R. Franchois, and R.K. 

Leonard, Changes in total ozone and ozone vertical distributions 

at South Pole, Antarctica, 1962-1987, Ozone in the Atmosphere, 

Proceedings, Quadrennial Ozone Symposium 1988 and 

Tropospheric Ozone Work.shop, edited by R.D. Bojkov and P. 

Fabian, pp. 28-31 , A. Deepak, Hampton, VA, 1989. 

Lowe, D.C., C. Brenninkmeijer, M. Manning, S.C. Tyler, E. 

Dlugokencky, P. Steele, and P. Lang, Carbon isotopic composition of atmospheric methane, paper A21A-4 presented at the Fall 

AGU Meeting, San Francisco, CA, December 4-8, EOS, 70(43), 

1017, 1989. 

Margitan, J.J., G.A. Brothers, E.V. Browell, D. Cariolle, M.T. 

Coffey, J.C. Farman, C.B. Farmer, G.L. Gregory, J.W. Harder, 

D.J. Hofmann, W. Hypes, S. Ismail, R.O. Jakoubek, W. Komhyr, 

S. Kooi, A.J. Krueger, J.C. Larsen, W. Mankin, M.P. McCormick, G.H. Mount, M.H. Proffitt, A.R. Ravishankara, A.L. 

Schmeltekopf, W.L. Starr, G.C. Toon, A. Torres, A.F. Tuck, A. 

Wahner, and I. Watterson, lntercomparison of ozone measurements over Antarctica, J. Geophys. Res., 94(Dl4), 

16,557-16,569, 1989. 

Matthews, W.A., W.D. Komhyr, and P.R. Franchois, Vertical 

distribution and variation in atmospheric ozone over Lauder, 

New Zealand, in Ozone in the Atmosphere, Proceedings, 

Quadrennial Ozone Symposium 1988 and Tropospheric Ozone 

Work.shop, edited by R.D. Bojkov and P. Fabian, pp. 85-87, A. 

Deepak, Hampton, VA, 1989. 

McPeters, R.D., and W.D. Komhyr, Long-term changes in 

SBUV{TOMS relative to the world primary standard Dobson 

instrument, in Ozone in the Atmosphere, Proceedings, Quadrennial Ozone Symposium 1988 and Tropospheric Ozone Work.shop, 

edited by R.D. Bojkov and P. Fabian, pp. 265-267, A. Deepak, 

Hampton, VA, 1989. 

Oltmans, S.J., W.D. Komhyr, P.R. Franchois, and W.A. Matthews, 

Tropospheric ozone: Variations from surface and ECC 

ozonesonde observations, in Ozone in the Atmosphere, 

Proceedings, Quadrennial Ozone Symposium 1988 and 

Tropospheric Ozone Work.shop, edited by R.D. Bojkov and P. 

Fabian, pp. 539-543, A. Deepak, Hampton, VA, 1989. 

Oltmans, SJ., W.E. Raatz, and W.D. Komhyr, On the transfer of 

stratospheric ozone into the troposphere near the North Pole, J. 

Atmos. Chem, 9, 245-254, 1989. 

Oltmans, SJ., R.C. Schnell, P.J. Sheridan, R.E. Peterson, S.M. Li, 

J.W. Winchester, P.P. Tans, W.T. Sturges, J.D. Kahl, and L.A. 

Barrie, Seasonal surface ozone and filterable bromine relationship in the high Arctic, Atmos. Envron., 23(11), 2431-2441 , 

1989. 

Oltmans, S.J., P.J. Sheridan, R.C. Schnell, R.E. Peterson, J.W. 

Winchester, L.A. Barrie, J.D. Kahl, and W.D. Komhyr, 

Springtime ozone fluctuations at high Arctic latitudes and their 

possible relationship to atmospheric bromine, in Ozone in the 

Atmosphere, Proceedings, Quadrennial Ozone Symposium 1988 

and Tropospheric Ozone Work.shop, edited by R.D. Bojkov and 

P. Fabian, pp. 498-501, A. Deepak, Hampton, VA, 1989. 

Peterson, J.T., NOAA long-term trace gas monitoring, paper presented 

at the U.S.-Taiwan Bilateral Workshop on Long-Term Air Quality 

Changes and Their Qimatic Impact, Taipei, Taiwan, November 

18-19, 1989. 

Sachse, G.W., K.B. Bartleu, R.C. Harriss, G.F. Hill L.O. Wade, L.G. 

Burney, J.E. Collins, Jr., and LP. Steele, Airborne measurements 

of methane and carbon monoxide during ABLE-3A, paper 

Al lA-04 presented at the Spring AGU Meeting, Baltimore, MD, 

May 7-23, EOS, 70(15), 282, 1989. 

Schnell, R.C., and B.A. Bodhaine, The Arctic basin atmospheric 

chemistry retort, paper 2D.1 presented at the 1989 Annual Meeting 

of the American Association for Aerosol Research, Reno, NV, 

October 9-13, 1989. 

Schnell, R.C., T.B. Watson, and B.A. Bodhaine, NOAA WP-30 

instrumentation and flight operations on AGASP-ll, J. Atmos. 

Chem., 9, 1-16, 1989. 

Steele, LP. , T J. Conway, L.S. Waterman, and P.M. Lang, The 

NOANGMCC measurements of CH4 and C02 from air samples 

collected at Cape Grim, in Baseline 1987, edited by B.W. Forgan 

and G.P. Ayers, pp. 48-50, Department of Administrative Services, 

137 
Bureau of Meteorology, in cooperation with CSIRO, Division of 

Atmospheric Research, Aspendale, Australia, 1989. 

Tans, P.P., T.J. Conway, and T. Nakazawa, Latitudinal distribution of 

the sources and sinks of atmospheric carbon dioxide derived from 

surface observations and an atmospheric transpon model, J. 

Geophys. Res., 94, 5151-5172, 1989. 

Thoning, K.W, T.J. Conway, P.P. Tans, and J.T. Peterson, Recent 

atmospheric C02 growth rates, Third International Conference on 

Analysis and Evaluation of Atmospheric C02 Data Present and 

Past, Hinterzanen, Federal Republic of Germany, October 16-20, 

1989, WMO Environmental PolluJion Monitoring and Reuarch 

Progress Report No. 59, 237, World Meteorological Organization, 

Geneva, Switzerland, 1989. 

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

dioxide at Mauna Loa Observatory, 2, Analysis of NOAA GMCC 

Data, 1974-1985, J. Geophys. Res., 94(D6), 8549-8565, 1989. 

Thoning, K.W., P.P. Tans, T.J. Conway, and LS. Waterman, 

Indication of a decrease in the amplitude of the C02 seasonal 

cycle, Third International Conference on Analysis and Evaluation 

of Atmospheric C02 Data Present and Past, Hinterzanen, Federal 

Republic of Germany, October 16-20, 1989, WMO Environmental 

Pol/uJion Monitoring and Research Progress Report No. 59, p. 

236, World Meteorological Organization, Geneva, Switzerland, 

1989. 

Waterman, L.S., D.W. Nelson, W.D. Komhyr, T.B. Harris, K,W. 

138 

Thoning, and P.P. Tans, Atmospheric carbon dioxide measurements at Cape Matatula, American Samoa, 1976-1987, J. Geophys. 

Res., 94(D12), 14817-14829, 1989. 
ACR 

ADVR 

AEM 

AEROCE 

AES 

A GASP 

AGL 

AGU 

ALIVE 

ALT 

ANL 

ANSTO 

AOML 

AQG 

ARL 

ARM 

ASCS 

ASL 

ATS 

BAO 

BAS 

BRW 

CAF 

CAMS 

CFC 

CFC-11 

CFC-12 

CIRES 

CMDL 

CN 

CNC 

COR 

CSI 

CSIRO/DAR 

CSU 

DB 

DEW 

OMS 

DNA 

DOT 

EPA 

DSIR 

DU 

ECC 

ECO 

EC-GC 

ECMWF 

EKTO 

EML 

ENSO 

EPA 

ERBE 

ERL 

FAST 

FID 

13. Acronyms and Abbreviations 

active cavity radiometer 

Advanced Very-High-Resolution Radiometer 

analytical electron microscope 

Atmosphere/Ocean Chemistry Experiment 

Atmospheric Environment Service, Canada 

Arctic Gas and Aerosol Sampling Program 

above ground level 

American Geophysical Union 

Atmospheric Lidar Val id at ion Experiment 

Alert Observatory, Canada 

Argonne National Laboratory 

Australian Nuclear Science and Technology Organization 

Atlantic Oceanographic and Meteorological Laboratory, Miami, Florida (ERL) 

Air Quality Group, Boulder, Colorado (ARL) 

Air Resources Laboratory, Silver Spring, Maryland (ERL) 

Aerosols and Radiation Monitoring Group, Boulder, Colorado (CMDL) 

Alaska Soil Conservation Service 

above sea level 

Application Technology Satellite 

Boulder Atmospheric Observatory 

British Antarctic Survey 

Barrow Observatory, Barrow, Alaska (CMDL) 

Clean Air Facility 

Control and Monitoring System 

chlorofluorcarbon 

trichlorofluoromethane 

dichlorodifluoromethane 

Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, Colorado 

Climate Monitoring and Diagnostics Laboratory, Boulder, Colorado (ERL) (formerly GMCC) 

condensation nuclei 

condensation nucleus counter 

correlation coefficient 

Columbia Scientific, Inc. 

Commonwealth Scientific and Industrial Research Organization/Division of Atmospheric Research, 

Australia 

Colorado State University 

direct-beam [irradiance] 

distant early warning 

dimethyl sulfide 

Deoxyribonucleic acid 

Department of Transportation 

Environmental Protection Agency 

Department of Scientific and Industrial Research, New Zealand 

Dobson units 

electrochemical concentration cell 

electron capture detector 

electron capture-gas chromatograph 

European Centre for Medium Range Weather Forecasts 

[a commercial name for a prefabricated building] 

Environmental Measurements Laboratory 

El Nino/Southern Oscillation 

Environmental Protection Agency 

Earth Radiation Budget Experiment 

Environmental Research Laboratories, Boulder, Colorado (NOAA) 

forward alpha scattering techniques 

flame ionization detector 

139 
FS 

FTIR 

GC 

G.E. 

GSFC 

GLOBE 

GMCC 

HASL 

HP 

HST 

IBM 

IC 

IMPROVE 

IR 

ISWS 

JPL 

LEAPS 

LST 

LW 

LWD 

LWRF 

MLO 

MLOPEX 

MSL 

NADP 

NASA 

NCAR 

NCS 

NDIR 

NIH 

NIP 

NIST 

NMC 

NOAA 

NOAH 

NPS 

NRBS 

NSF 

NSO 

NWR 

NWS 

OGC 

OGIST 

PBL 

PC 

PDB 

PESA 

PIXE 

PMEL 

PMOD 

PMT 

PRC 

PSC 

PSI 

PTFE 

p3 

RITS 

RSD 

Forest Service 

Fourier transform infrared (spectroscopy) 

gas chromatograph 

General Electric 

Goddard Space Flight Center 

Global Backscatter Experiment 

Geophysical Monitoring for Climatic Change, Boulder, Colorado (ARL) (now CMDL) 

Health and Safety Laboratory 

Hewlett-Packard 

Hawaii standard time 

International Business Machines 

ion chromatography 

Interagency Monitoring of Protected Visual Environments 

infrared 

Illinois State Water Survey 

Jet Propulsion Laboratory 

Low Electron Attachment Potential Species 

local standard time 

longwave 

longwave downward irradiance 

longwave radiative forcing 

Mauna Loa Observatory, Hav.:aii (CMDL) 

MLO Photochemical Experiment 

mean sea level 

National Atmospheric Deposition Program 

National Aeronautics and Space Administration 

National Center for Atmospheric Research 

Navigation Consulting Services 

non-dispersive infrared analyzer 

National Institutes of Health 

normal incidence pyrheliometer 

National Institute for Standards and Technology (formerly NBS) 

National Meteorological Center 

National Oceanic and Atmospheric Administration 

Nitrous Oxide And Halocarbons Group, Boulder, Colorado (CMDL) 

National Park Service 

non-Rayleigh backscatter 

National Science Foundation 

National Solar Observatory 

Ni wot Ridge, Colorado 

National Weather Service 

Oregon Graduate Center (now OGIST) 

Oregon Graduate Institute of Science and Technlogy (formerly OGC) 

planetary boundary layer 

personal computer 

pee dee belemnite 

proton elastic scattering analysis 

Proton-Induced X-ray Emission 

Pacific Marine Environmental Laboratory, Seattle, Washington (ERL) 

Physikalisch-Meteorologisches Observatorium Davos [World Radiation Center] 

photomultipier tube 

People's Republic of China 

Polar stratospheric cloud 

Paul Scherrer Institute, Switzerland 

polytetrafluoroethylene (Teflon) 

Portable Pressurizer Pack (air sampler) 

Radiatively Important Trace Species 

residual standard deviation 

140 
SAGE 

SASP 

SBUV 

SC 

SEAR EX 

SEASPAN 

SERI 

SIO 

SMO 

SOI 

SOLRAD 

SPO 

SRF 

SRM 

SUNYA 

TECO 

TEM 

TOMS 

TSI 

TSL 

TSP 

UCI 

URAS 

URI 

USDA 

USGS 

UT 

UV 

UVB 

WCRP 

WMO 

WPL 

Stratospheric Aerosol and Gas Experiment 

Surface Air Sampling Program 

solar backscattered ultraviolet (satellite ozone instrument) 

sky cover 

Sea-Air Exchange Experiment 

SEAREX South Pacific Aerosol Network 

Solar Energy Research Institute 

Scripps Institution of Oceanography 

Samoa Observatory, American Samoa (CMDL) 

Southern Oscillation Index 

Solar Radiation 

South Pole Observatory, Antarctica (CMDL) 

Solar Radiation Facility (CMDL) 

standard reference material 

State University of New York at Albany 

Thermal Electron Company 

transmission electron microscope 

Total Ozone Mapping Spectrometer 

Thermo Systems Incorporated 

Technical Services Laboratory 

total suspended particulate 

University of California, Irvine 

[a commercial col analyzer] 

University of Rhode Island 

United States Department of Agriculture 

United States Geological Survey 

universal time 

ultraviolet 

ultraviolet B band 

World Climate Research Program 

World Meteorological Organization 

Wave Propagation Laboratory, Boulder, Colorado (ERL) 

<>U.S. GOVERNMENT PRINTING OFFICE: t 9 9 t - s 7 3 - o o 2/2 1 o 6 s 141