u.s. DEPARTMENT 

OF COMMERCE 

NATIONAL 

OCEANIC AND 

ATMOSPHERIC 

ADMINISTRATION 

ENVIRONMENTAL 

RESEARCH 

LABORATORIES 

rl Report 1981 

• 

• 

• 

• 
Geophysical Monitoring 

for Cli matic Change 

No. 10 

Summ ary Report 1981 

Barry A. Bodh aine and Joyce M. Harris, Ed itors 

Air Resources Laboratories 

Geophysica l Mon itoring for Climatic Change 

Boulder, Colorado 

December 1982 

U.S. DEPARTM ENT DF COMMERCE 

Malcolm Baldrige, Secretary 

National Oceanic and Atmospheric Administration 

John V. Byrn e, Admin istrator 

En vironmental Research Laboratories 

George H. Ludwig, 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. 

ii 
CONTENTS 

FOREWORD . 

PREFACE . 

ACRONYMS. 

1. 

2 . 

3. 

4. 

Sill1l'lARY . 

OBSERVATORY REPORTS 

2 .1 

2 . 2 

2.3 

2 .4 

~Iauna Loa . 

Barrow . . 

Samoa. . . 

South Pole 

CONTINUING GMCC PROGRMIS 

3 . 1 

3.2 

3 . 3 

3.4 

3.5 

3.6 

3 .7 

3.8 

3.9 

3.10 

3.11 

3.12 

3 .13 

Carbon Dioxide 

Tota 1 Ozone. . 

Ozone Vertical Distribution. 

Surface Ozone . 

Stratospheric Water Vapor .. 

Halocarbons and Nitrous Oxide. 

Stratospheric Aerosols--Lidar. 

Surface Aerosols . . 

Solar Radiation ..... 

Station Climatology. . . 

Precipitation Chemistry. 

Data Management ..... 

Atmospheric Trajectories 

SPECIAL PROJECTS . . . . . . . 

4.1 

4.2 

4.3 

4.4 

4.5 

4.6 

4.7 

4 . 8 

4.9 

4.10 

4 .11 

4.12 

4.13 

Modeling the Atmospheric CO 2 Concentration 

Analysis of SPO's CO 2 Record for 19 76 -1980 

Atmospheric CO 2 Variations Measured in the North 

Pacific Region and the Southern Oscillation . . . 

CO 2 Flux Estimation at BRW . . . . . . . . 

Air Mass Types Associated With Extremes in Winter 

CO 2 Co ncentration at BRW . . . . . . . . . . . . . 

Calibration of Pollak Condensation Nucleus Counters. 

Supersaturation and Expansion Ratios i n Condensation 

Nuc l eus Counters . . . . . . . . . . . . . . . . . 

Correction to Long-Term Umke hr Data Using the MLO 

Solar Transmission Record .......... . 

Compa risons Between Backscattered Ultraviolet , Standard 

Umkeh r, and Short Umkehr Measurements of Ozone 

Concentration . ............ . 

Cloud Chemistry and Radiation Experiment at Whiteface 

Mountain, N.Y .. ...... . .... . 

Calibration of a Solar Infrared Hygrometer 

Sunphotometer Intercomparison. . 

The Photovoltaic Power System at SMO ... 

iii 

Page 

v 

vii 

viii 

1 

4 

4 

9 

12 

16 

21 

21 

29 

31 

34 

34 

37 

40 

41 

49 

58 

65 

68 

71 

75 

75 

76 

78 

81 

84 

85 

87 

89 

92 

94 

98 

101 

102 
5. 

6. 

7 . 

8. 

9. 

COOPERATIVE PROGRMlS . . . 

5.1 

5.2 

5.3 

5.4 

5.5 

5.6 

5.7 

5 .8 

5 .9 

5.10 

5.11 

5. 12 

5.13 

5. 14 

5.15 

5. 16 

Ultraviolet Erythema Global Measuring Network 

(D. Berger) . . ... ... . ... ... .. ..... . 

NO fleasurements at flLO (J. F. Noxon) ......... . 

OnXthe Relationship Between Surface Air Temperature and 

Concentration of Pollution-Derived El ements at BRW 

(W . E. Raatz). . . . . ..... . 

Atmospheric 210Pb at BRW and MLO (H. W. Feely and 

C. G. Sanderson) .. . ......... . 

Air Chemistry Monitoring at Palmer Station (E. Robinson 

and W. L. Bamesberger). . . ... . . . .. . 

SEAREX Atmospheric Chemistry Studies at SflO (B. J. Ray 

and R. A. Duce) ...... .. ..... . 

Atmospheric Trace Gases and Arctic Haze at BRW 

(R. A. Rasmussen and M. A. K. Khalil) .. 

Time Series Analysis of Light-Scattering Data from 

flLO (M. Da rzi and J. W. Winches ter). . . . . . . . 

Radiation fleas urements at BRW (G. Wend l er and F. Eaton) .. 

Optical Measurements of Blowing Snow at SPO (F. Eaton 

and G . Wendler). . . . . . . . . . . . . . . . . . 

Light Absorption Studies at MLO (A. D. Clarke and 

R. J . Charlson) ........... . .. . 

Eight-Year Air Chemistry Measurement Pro gram a t 

SPO (D. Cronn and E. Robinson) . . . 

Trace-Element Sampling at BRW (K. A. Rahn) . 

Graphitic Carbon-to-Lead Ratio as a Tracer for Sources 

of the Arcti c Aerosol (H. Rosen, A. D. A. Hansen, 

T. Novakov, and B. A. Bodhaine) ..... . .... .. ... . 

Effects of Sulfate and Non-Sulfate Particles on Light 

Scattering and Precipitation Chemistry at MLO 

(A. C. Dittenhoefer) ........... . 

Stochastic Simulation Modeling of the Global 

Carbon Cycle (L. P. Stee l e). 

INTERNATIONAL ACTIVITIES . . . 

PUBLICATIONS AND PRESENTATIONS BY GMCC STAFY, 1981 

REFERENCES . 

GMCC STAFF, 1981 

iv 

Page 

105 

105 

105 

106 

107 

108 

109 

114 

120 

124 

125 

125 

131 

132 

134 

137 

140 

142 

144 

148 

157 
FOREWORD 

It is a pleasure to introduce this 10th anniversary volume of the G~!CC 

annual report . GMCC had its origins in early 1971 when Don Pack, ARL Deputy 

Director, prepared a program development plan for submission to t he NOAA administration. That plan outlined certain necessary climate-rela t ed research 

and monitoring programs to be done within NOAA. Mu ch of the pl an was approved, and early in fiscal year 1972 GMCC was formed within ARL of NOAA. 

Don Pack served as the first director until his retirement in 1975, when 

Kirby Hanson became director. 

During these first 10 years, GMCC matured as a scientific organization. 

I nitia lly, mu ch of the effort was devoted to construction of observatories at 

Barrow, Samoa, and the South Pole; developing new programs; purchasing and 

siting instruments at the observatories; and developing data processing procedures. Now, with logistical and operational aspects of many programs operating smoothly, we have more time for data analysis. Consequently, program maturity has been evidenced by significant publications on interpretation of our 

data. 

We now have four primary areas of effort in GMCC. First, we maintain and 

operate our four baseline observatories. A major accomplishment of the pa st 

year was hosting the SEAREX experiment at Samoa, an intensive investigation of 

sea -air exchange of trace species by a consortium of university and private 

investigators. Second, we devote a major effort toward the CO 2 -climate problem. GMCC has taken the l ead, both nationally and internationally, in the 

monitoring of atmospheric concentrations of CO 2 , R~cently, we have completed 

expansion of our flask sampling network to 20 locations. Our third major interest involves studies related to ozone depletion. During 198 1 we developed 

the capability to make routine and inexpensive ozone sound ings to 40 km by 

means of a balloon-borne instrument package. Finally, we focus on atmospheric 

aeroso ls and their impact on solar radiation. Particular accomplishments were 

an e nhanced understanding of Arctic haze at Barrow and a clear documentation 

of dust transport from Asia to Hawaii during spring, with its associated 

impact on solar radiation reaching Mauna Loa. 

The year 198 1 was one of transition, both within GMCC as I became Director, and also in the Federal Administration. A new NOAA Administrator, John 

Byrne, and a new ERL Director, George Ludwig, were appointed. The goals of 

the new Administration in Washington have been c learly stated to be less 

Federal involvement in many areas and a reduced Federal budget . Our challenge 

is to maintain and improve our important scientific programs within this outloo k of constrained resources. I am confident that we will meet this challenge. 

v 

J. T. Peterson 

Director 

Geophysical Monitoring 

for Climatic Change 

PREFACE 

This document presents a summary of the research operations and accomplishments by the Geophysical Monitoring for Climatic Change (G~ICC) program 

and by outside investigators working cooperatively with GMCC in 1981. It includes descriptions of management and operations at GMCC's four baseline sites, 

scientific data from the measurement projects, conclusions from analyses of 

data, and recent basic research achievements. 

The GMCC program, established in 1971, is one of five research programs 

within the Air Resources Laboratories under t he directorship of Lester Machta. 

Its four observatories are located at Barrow, Alaska (in service since 1973); 

Mauna Loa, Hawaii (in service since 1956); American Samoa (in service since 

1973); and South Pole (in service since 1957). Background measurements of 

aerosols, gases, and solar radiation that are important to the climate of the 

Earth are made at the observatories. The primary groups within GMCC are 

Monitoring Trace Gases, Aerosols and Radiation Monitoring, Acquisition and 

Data Management, and Analysis and Interpretation. Specific names of individuals in GMCC are not given in the main text of the report; however, t he 

members hip of each GMCC group is given in sec. 9. Publications and presentations by GMCC staff are given in sec. 7. 

vii 
ACR 

A&D~l 

ALE 

ARL 

ARM 

ASCS 

ASRC 

A.U. 

BRW 

BUV 

CAF 

CDC 

C~1A 

CN 

CNC 

CSIRO 

DN 

DOE 

DOY 

dpm 

ECC 

EDXA 

EML 

EPA 

ERL 

GMIBIT 

G.E. 

GMCC 

HASL 

IAEA 

ICDAS 

II CAMS 

IR 

IS 

KUl'1 

LBL 

MLa 

MSL 

NADP 

NARL 

NCC 

ND IR 

NIP 

NMC 

NOAA 

NRL 

NSF 

NWR 

NWS 

OGC 

OPC 

ACRONY~IS AND ABBREVIATIONS 

Active cavity radiometer 

Acquisition and Data ~lanage ent (mICC), Boulder, Colo . 

Atmospheric Lifetime Experiment 

Air Resources Laboratories, Rockvi lle , Md. (ERL ) 

Aerosols and Radiation Monito ring (GMCC ) 

Alaska Soil Conservation Service 

Atmospheric Sciences Research Cente r, SUNYA, Albany, N.Y. 

Astronomical Unit 

Barrow Observatory, Barrow, Al aska (GMCC) 

Backscattered ultraviolet 

Clean Air Facility 

Control Data Corporation 

Chemical Manufacturers Association 

Condensation nuclei 

Condensation nucleus counter 

Commonwealth Scientific and Industrial Res ea rch Organization , 

Aus tra lia 

Departure from normal 

Department of Energy 

Day of year, Julian 

Disintegrations per minute 

Electrochemical concentra tion cell 

Energy dispersive X-ray analysis 

Environmental Heasurements Laboratory (DOE) 

Environmental Protection Agency 

Envi ronmenta 1 Resea rch Labora tories , Bould er, Colo. (NOAA) 

Gridded atmospheric multileve l backward isobaric trajec tories 

General Electric 

Geophysical ~loni to ring for Climatic Change, Boulder, Colo. (ARL) 

Health and Safety Laboratory (EPA) 

International Atomic Energy Agency, Vienna, Austria 

Inst rumentation Co ntrol and Data Acquisition System 

Interactive Instrumentation Control and Monitoring System 

Infra red 

Integrating sandwich 

Cape Kumukahi, Hawaii 

Lawrence Berkeley Laboratory, Berke ley, Calif. 

Mauna Loa Observatory, Hawaii (GHCC) 

~lean sea level 

National Atmospheric Deposition Program 

Naval Arctic Research Labora t ory, Barrow, Alaska 

National Climatic Center , Asheville, N.C. 

Nondispersive infrared 

Normal incidence pyrheliometer 

National Meteorological Center, Suitland, Md. 

National Oceanic and Atmospheric Administration 

Naval Research Laboratory, Was hington , D.C. 

National Science Foundation, Wa shington, D.C. 

Niwot Ridge, Colo. 

National Weather Service 

Oregon Graduate Center , Beave rton, Ore. 

Optical particle counter 

viii 
PIXE 

PRON 

p3 

RDOS 

SBUV 

SCN 

SEAREX 

SEN 

SIO 

SNO 

SPO 

SRL 

SST 

SUNYA 

URI 

USGS 

UPS 

UV 

WDC-A 

Wl10 

WPL 

WSU 

Parti c l e i nduced X-ray emission 

Programmable r ead-only memory 

Portable pressurizing pack 

Real-Time Dis k Operating Syst'em 

Solar backscattered ultraviolet 

Standard cub ic meter 

Sea -Air Exchange program 

Scanning elec tron microscope 

Scripps Institute of Oceanography, La Jolla, Ca lif . 

Samoa Observatory, American Samoa (GNCC) 

South Pole Observa t ory, Antarcti ca (GNCC) 

Smith sonian Institution Radiation Biology Laboratory 

Sea surface temperature 

State University of New York at Albany 

Universit y of Rh ode Island, Kingston, R.I. 

United St ates Geological Survey 

Universal power supply 

Ultraviol et 

World Data Center-A, Asheville, N.C . 

World Ne t eoro l ogica l Organization, Geneva, Switzerland 

Wave Propagation Laboratory (ERL), Boulder, Colo. 

Wa s hington State University, Pullman, Wash. 

ix 

GEOPHYSICAL NONITORING FOR CLlNATIC CHANGE 

NO . 10 

Summary Report 1981 

1 . SUNl'IARY 

At NLO, a computer system, consisting of an LSI-11/2 processor, disk, 

t erminal, and printer, was installed and made operational in the Hilo office. 

A second computer system, consisting of an LSI -11/23 processor, terminal, and 

casse tte tape unit for upgrading the lidar system, was received and made ready 

(or installation. Plans for the construction of lava barriers upslope from 

flLO were comp leted during the year. In the event of a volcanic eruption near 

the sumillit of Hauna Loa, a lava flow approaching the observa tory would be diverted for all but very large flows. 

At BRW, NARL remained in a caretaker status, and BRW continued to receive 

power from an existing generator that has remained in opera ton at NARL. A 

14- x 20 -ft hut was acquired from NARL and installed near the GflCC station to 

act as a garage for station vehicles. 

At SNO, the SEAREX sampling program was comp leted as part of a comprehensive experiment to investigate gaseous and aerosol sea-air exchange. Three 

buildings located on Natatula Point and one building on the ridge remain for 

lise by the GflCC program. A five-section tower was construc ted on Hatatula 

Point to act as the sampling platform for the GNCC CO. program. 

At SPO, no significant additions to facilities were made, and all programs operated normally. GNCC propo sed to the NSF that a Clean Air Sector be 

maintained upwind from the station between 3300 and 1100 grid directions. 

The routine GNCC measurement programs at the observatories continued. 

These include carbon dioxide, total column and surface ozone, CFC-11 and - 12, 

Ilitrous oxide, aerosol scattering coefficient, eN concentration, solar radiation, precipitation chemistry, and meteorological variables. Balloon mea s urements of stratospheric water vapor and ozone profiles were continued in 

Boulder, as were Umkehr ozone profiles. Lidar measurements of stratospheric 

aerosol profiles continued at NLO. Total ozone measurements continued at the 

four GMCC stations, one foreign cooperative station, and seven stations in the 

contiguous United States . Ozone observations were reinstated a t the Tallahassee, Fla., station. The C02 flask sampling program included a total of 20 

si tes , with new stations established at Ocean Station M and Falkland Islands. 

Data for 1979-1981 show a clear seasonal cycle superimpo sed on a secular 

growth rate of abo ut 1.4 ppm yr- 1 . The amplitude of the seasonal cycle is 

Illaximum at the northernmost latitudes and is small in the Southern Hemisphere. 

Participation conti nued in the Wl'10 Global Ozone Research and flonitoring 

Project to upgrade Dobson spectrophotometers thro ughout the world. Automation 

of a Dobson instrument for routine Umkehr measurements was completed . That 

instrument may also be used in a semiautomatic mode for the measurement of 

total ozone. 
Halocarbon and N20 analysi s capabilities were increased through the 

addition of a totally reconditioned gas chromatograph in t he Boulder laboratory. An absolute calibration system for trace gases such as CFC- II, 

CFC-I2, a nd N2 0 was devised. This system involves the preparation of a mixture of t he gas with CO 2 , dilution to trace levels, and subsequent detection 

using the standard CO 2 meas ureme nt te chnique with highly accurate CO 2 gas 

standards. Sampling of CFC- 11 , CFC-12, and N20 continued at five sites. 

CFC-1 1 and CFC- 12 data show mean mixing ratios i n the ranges 188-205 pptv 

and 321-345 pptv, respectively, and growth rates in the ranges 11-) 4 pptv yr 1 

and 12-18 pptv yr- 1 , respectively. N2 0 data show mean mixing ratios in the 

range 301-304 pptv, indicating that the gas is wel l mixed globally . N2 0_ 

growth rates for BRW, NWR , MLO, and SPO are in the range 0.5-1.8 pptv yr 1 

A modification of the ARL trajectory program was implemented on the NOAA 

CDC 750 comp uter i n Boulder. The new program computes and displays isobaric 

trajectories at multip l e pressure levels. These back trajectories can be 

calculated for up to 10 days for any destination in the Northern Hemisphere. 

A climatology of trajectories is being assembled for MLO and Bermuda. 

GMCC personnel conducted nwnerous research projects and data analyses 

based on the routine measurement programs. Several studies used the CO 2 data 

record. A two-dimensional model of the global CO 2 distribution was developed 

t hat includes atmospheric mi xing , oceanic uptake, biospheric fluxes, and fossil fuel combustion. By variation of the unknown parameters it is possible to 

interact with the model to facilitate the planning of sampling strategies and 

the estimation of oceanic and biospheric CO 2 fluxes. Analysis of the SPO CO 2 

record for 1976- 1980 showed that the data can be approximated by a function 

incl ud i ng a t hird-degree polynomial and first and second harmonics. An annual 

cycle and secular increase are clearly evident in the data. Correlations 

among CO 2 variations and sea surface temperature in the North Pacific, and the 

Southern Oscillation were examined. The Southern Oscillation may influence 

sea surface temperatures, whic h in turn may affect CO 2 concentrations. A 

study of t he CO 2 vertica l flux over the Arctic tundra at BRW was performed 

using sampling l ines at 0.3- and 10-m heights. The results suggested that the 

BRW CO 2 cycle can be f ully explained only by including the influence of midlatitude vegetation . In a case study, air masses at BRW were c l assified into 

two types by l ook ing at radiosonde wind, temperature, and moisture profiles as 

well as meteorological parameters at t he station, and computed trajectories . 

CO 2 concentrations tended to be higher when an Arctic air mass was present, 

i.e., co ld , dry ai r with a l ong residence time in the Arctic . When a warm, 

wet air mass from the North Pacific or North Atlantic regions was present, CO 2 

concentrations tended to be low. 

A laboratory experiment was performed to verify the calibration of CNC's. 

Furthermore, because confusion was found in the literature, a consistent 

theory of expa nsion ratio and s upersaturation in CNC's was developed. 

Work continued on development of the Umkehr method for measurement of 

ozone profiles i n the atmosphere and development of a method for the correction of Umkehr data for the effects of stratospheric aeroso l s using the MLO 

solar radiation record. Ozone data collected using the BUV instrument and the 

Umkehr method were compared to study the degradation with time of satelliteborne BUV. 

2 
A sununer experiment was organized at Whiteface ~1o unt ai n to investigate 

the absorption of solar radiation in c l ouds and the effects of aerosol scavenging in the clouds. This was the first comprehensive attempt to meas ur e the 

effects of absorbing aerosols located both within and between c l oud droplets. 

The GMCC standard solar infrared hygrometer was calibrated in Boulder by 

comparison with Denver radiosonde data and a WPL mi crowave water vapor meter. 

GMCC sponsored a comparison of 12 sunphotometers of 5 different types by means 

of atmospheric observations over a 2-mo period in Boulder . 

Under a DOE grant, a contract was let for the construction of a photovolta i c power system at SMO. This so l ar power system will provide 1 kW of 

continuous power and will have sufficient battery backup t o carr y the electrical load of the observatory for two consecutive sunl ess days. 

In 1981, GMCC again supported a substantia l number of coopera tive research projects. These projects are listed in sec. 2 for each station. Sixteen summary reports from these cooperative projects are i nc luded in sec. 5. 

They cover such topics as the global network of erythema meas urements; measurement of tropospheric NO at MLO, with a novel method using t he rising and setting s un and moon as li~ht sources; severa l studies on pollution-derived aerosols and gases at BRW, MLO, SMO, and SPO; a comprehe nsive r eport on t he SEAREX 

program at SMO; studies on the light absorptive properties of aeroso l s at MLO 

using a new technique called the i ntegrating sandwich; sources of the Arctic 

aerosol using the ratio of graphitic carbon to lead as a tracer; some effects 

of sulfate and nonsulfate aerosol particles on light sca ttering and precipitation chemistry at MLO; and mathematical models of the global carbon cycle usiug methods derived from control and system theory. 

3 
2. OBSERVATORY REPORTS 

2.1 Nauna Loa 

2. 1.1 Facilities 

A major improvement in NLO facilities was effected in 198 1 by the purc hase of a powe rful computer system for the Hilo office. Although there were 

serious problems with the system as it was delivered (damaged heads on the 

disk system, seve ra l f eatures not i ncluded, and the mounting cabinet not 

s h ipped), the problems were eventually resolved and t he ba sic system was 

insta l led a nd operationa l by October. The comp one nts in the basi c system are 

t he LSI-Il/2 central processing unit, magnetic disk, video terminal, and line 

printer . Periphera l s that were purchased, but not installed by the end of the 

year , are a nine-track tape drive, TU-58 cartridge system, automatic plotter, 

and paper-tape reader . The system operated reliably and received relatively 

heavy usage for various aspects of the NLO program during the last 3 months of 

the year . 

The comp etiti ve bids for a second, but less complete, computer system 

were received in Septemb er, and the computer was delivered in October . This 

second system is to be used for upgrading the lidar operation , and for eventua l a utomation of lidar observations. Although the LSI-ll /23 central processing unit is more powerful than that in the Hilo office, the peripherals for 

it consist of only a video terminal and a TU-58 tape cartridge system. The 

system was awaiting delivery of the bootstrap, read-only memory, and parallel 

I/O boards at year's end. 

Since the tele scope dome that presently houses the lidar will be needed 

for a new solar tracker, the decision was made to erect a specially modified 

steel building for the lidar . The principal modification required was a n 

opening in the roof for the lidar observations . Design specifications for the 

building and roof opening were completed in August, and a contra c t was let in 

Septemb er to Porta House, Inc . , Oakland, Calif., for supply of the prefabricated building (without the roof opening) . The building had not yet arrived 

in Hilo by t he end of the year . 

Be ca use of operational problems with the four-wavelength nephe lome ter, 

t he i nstrument was taken offline a nd shipped to Bo ulder for repair in late 

June. Unfortunately , repair was delayed and no nephelometer data were obtained from 1 J une to 31 Decembe r . 

A G.E. dewpoint hygrometer, installed at NLO in early February, operated 

largely trouble free during mo s t of the year . 

Operation of ICDAS was reasonably satisfactory , but the problem of spurious rewinding of the magnetic tape, with a consequent outage of the system, 

was exper ienc ed several times during the year. In an attempt to minimi ze the 

effects of t he tape rewinds, a software routine was added in February to the 

operational program to reposition the tape at the end-of-file mark before 

writing on t he tape . This was moderately successful for a utomatic recovery 

from a spurious rewind. 

Since t he observatory is lo cated about 45 mi from Hilo and ICDAS failures 

can occur at any time, it was decided that a method of checking on system 

4 
operation by tel ephone would be desirable. Such a device was developed by the 

observatory staff and was installed in March. It has proved to be very us eful, parti cularly on holidays and weekends, for che cking system status, and on 

severa l occasions t he period of outage has been decreased. 

In July a replacement NOVA 1220 computer was installed in an attempt to 

increase the reliability of ICDAS ope rations. The frequency of outages was 

decreased, but not completely e limi nated, by the replacement. System failures 

due to sta ti c discharges were also minimized by the insta llation of antistatic 

mats around the ICDAS rack. In spite of all mea sures taken, however , some 

failures continued throughout the yea r . 

A supply of spare parts (Pockels cell, r'lby rod, flash lamp, optical 

reflectors) for the lidar system was assembled in late 1981 in an effort to 

prevent any long interruptions of lidar operation in the future. A main contributing fa ctor to component fai lures during 1981 was the vertical orientation of the laser, which permits dust particles to fallon the optical surfaces thus causing hot spots to develop in t he laser beam . A logical so lution 

to this fallout dust problem would be to mount the laser in a horizontal 

o rientation a nd install a reflecting mirror for projecting the beam vertica lly . Such a provision should be considered in future planning for the 

system. 

Detailed plans were completed for the construction of lava barriers upsl ope f rom the observatory for diverting po ssible lava flows resulting from 

volcanic eruptions near the summit of tlauna Loa. J. Lockwood of the Hawaiian 

Vo l ca no Observa tory, who was mainly responsible for the plans, made arrangements for H. Moore of USGS , Menlo Park, Ca lif., to analyze the behavior of 

lava flows approaching such diversion barriers, using numerical mode l s. 

Moore's study indicated that the proposed barriers would indeed protect the 

observatory from a ll but very large volume s and speeds of lava flows and that 

it was unlikely that the upper reaches of Mauna Loa would generate such large 

flows. Thus it was decided t o proceed with the project as time and budget 

permit, and to retain Lockwood as project leader for the task. 

Howa rd T. Ellis, who served on the observatory staff since February 1961, 

retired in February 1981 after 20 years at MLO. A personal account of his 

experiences during the early years a t MLO ca n be found in Ellis (1978). 

2. 1. 2 Programs 

The principal programs carried out at MLO during 1981 are lis ted in 

table 1. Brief comments on the programs follow. 

Carbon Dioxide 

The concentration of atmospheric CO 2 was continuously monitored by GMCC's 

URAS-2 NDIR gas analyzer thFoughout the year . The instrument performed satisfactorily without maj or problems. Preliminar~ results indicated that the rate 

of i ncrease of atmospheric CO 2 was 1.5 ppm yr 1 for 1981. 

The weekly CO 2 flask sampling programs for GMCC at MLO and KUM were 

carried out successfully during the year. The sampling programs involved 

exposing a pair of evacuate d 5 - 2 flasks and expos ing, by flush and fill 

5 
Table 1.--Swnmary of sampl i ng programs at NLO in 1981 

Program 

Gases 

ca;bon dioxide 

Surface ozone 

Tota} ozone 

Halo carbons 

Aerosols 

Condensat i on IHIC Ie i 

Optical properties 

Stratospheric aerosols 

Skylight polarization 

Solar Radiation 

Global irradiance 

Direct irrad iance 

Turbidity 

~Ieteorology 

Air temperature 

Soil temperature 

Del-'point temper ature 

Relative humidity 

Pressure 

Wind (speed and direction) 

Precipitation 

Tota I precipi table I-'ater 

PreCipitation Chemistry 

pH 

Condu ctivity 

Chemical components 

Coopera tive Programs 

Carhon dioxide (SID) 

Carbon monoxide Ulax 

Planck lnst.) 

Surface S02 (EPA) 

Total surfa ce particulates 

( DOE) 

Instrument 

URAS- 2 infrared analyzer 

0.5 - £ glass flasks, pl 

0.5-£ glass flasks, through analyzer 

5- £ evacuated g lass flasks 

Dasibi ozone meter 

Dobson spe ctrophotometer no. 63 

Dobson spectrophotometer no. 83 

300- ml stain less Sleel fla s ks 

Pol l ak CNC 

G.E. CNC 

Four-",'avelength nephelometer 

Lidar 

Polarizing radiometer 

Eppley pyranometers: Q, RG8 

Eppl ey pyrheli omete r: Q 

Eppley pyrheliometer: Q, OGl, RG2, RG8 

Eppley pyrheliome ter 

with i3 narrowba nd filt ers 

Sunpho t ometer .... ith 380- and SOO -nm 

na rro ... 'ba nd filters 

Thermisto r 

tlax. -min. thermometers 

Hy gro thermograph 

Thermistor 

Dewpoint hygrometer 

Hygrothermog r aph 

Sling psychrometer 

Capacitance transducer 

Hicrobarograph 

~Iercurial barome t er 

Bendix Aerovane 

Rain B"'ge, 8- in 

Rain gage, B-in 

Rain gage, tipping bucket 

Foskett infrared hygrometer 

pH meter 

Conduc tivity bridge 

Ion chromatograph 

Infrared analyzer (Appl ied Physics) 

5- £ evacuated glass flasks 

Special system 

Chemical bubbler system 

High-vol ume sampler 

Total surface parti culates Hi gh-volume sample r 

(EPA) 

Atmosphe ri c e l ec t r i ci ty 

(Univ . of ~linnesoLa) 

Ultraviole t radiation 

(Temple Un i v.) 

Precipilation collection 

(DOE) 

Precipi l ation co llecti on 

(EPA) 

Precipitation co llec ti on 

(Univ. o f Paris) 

Precipi tation col lecti on 

(lAEA) 

!,o,'et-dry deposition 

(Univ. of Illinois) 

Aerosol chemistry 

(florida State Univ. 

Aerosol chemistry 

(Univ. of Maryland) 

Aerosol chemi stry 

(Univ. of Califo rnia ) 

Aerosol chemis try 

(Univ. of Arizona) 

Carbon-I) (USGS) 

Field mill, air conductivity meter, 

surface antenna 

Ultraviolet radiometer 

HASL .... et-d ry collect o r 

Hisco model 93 

Likens funnel collector 

Likens funnel co l l ecto r 

Exposed collection pail s 

Special filters 

Nuclepore filters 

Nu c l epore filters and impactors 

Quartz filters 

10 - 1 stain less steel flasks 

6 

Sampling 

frequency 

Continuolls 

I pair ... 'k- I 

1 pair .... k- I 

I pair ... ·k- I 

Continuous 3 day - I 

Discre t e 1 pair ... 'k- I 

Discrete 

Co ntinuous 

Con tinuous 

Disc rete 

Discrete 

Continuous 

Conti nuous 

Di scre t e 

Continuous 

Discrete 

Co ntinuous I day - I 

Co ntinuous 

Co nt i nuous 

Continuous 

Cont inuous 

Discrete 

Continuous 

Con tinuous 

Discrete 

Continuous 

1 day-I 

Twice wk-' 

Cont inuous 

Continuous 

Discrete 

Discrete 

Discre t e 

Continuou s 

1 pair ... 'k- I 

Continuous 

Every 12 days 

Continuous 

Every 12 days 

Continuous 

Co ntinuous 

Continuous 

Continuous 

T .... ice wk- I 

Twice .... k- I 

Con tinuous 

COllti nuous 

Con ti nuous 

Night only 

Cont inuous 

Rema rks 

ountain and seacoast 

ou nta in and seacoast 

Special obs . during summer 

4 meas., ",'eekdays; 0 , weekends 

450, 550, 700 . 850 nm 

694 . 3 nm, 2 J 

8 I-'avel engths 

I1LO and Kulani Hauka 

HLO and Kul ani Mauka 

Kul ani Hauka 

Rain .... ater col lections , 6 s ites 

Hountain and seacoast 

Equipment inoperab l e a fter 

26 Jan 

De pe nde nt on .... ind direc tion; 

1 filter wk- I 

Radiati on responsible for sunburning of s ki n 

NADP 

Equ ipmen t inoperable after 

22 Jul 

Day- nigh t disc r iminati on 

Day-ni ght di sc riminati on 
Table 2.--Monthly occurrences of outgassing from the 

vo l canic caldera on Mauna Loa 

Jan Fe b Mar Apr May Jun Jul Aug Sep Oct Nov Dec 

No . of days 1 5 6 5 2 7 8 5 9 11 6 7 

Percent of days 3 18 19 17 6 23 26 16 30 35 20 23 

methods, a pair of 0 .5-2 double-stopcock fla sks at both locations . No flasks 

were lost or broken during s hipment. 

Vertica l profiles of CO 2 at MLO were studied during 1981. Nine air in -

takes were mounted at 10- f t intervals from gro und l evel to 80 ft. Air from 

each i ntake line was sampl ed for 5 minutes. Thus, air from five different 

intake lines could be samp led in a 3D-min period. A reference gas of known 

concentration of C02 was used to comp are with the air samp les at ~-h interva l s . A URAS-1 NDIR gas analyzer was used for the measurements, and data were 

recorded on a strip chart recorder. All data were analyzed by hand. The prelimina ry results show that the differences in CO2 concentration at different 

heights a long the 80-ft tower were negligibly small (within 0.5 ppm) . 

Outgassing from the volcanic caldera at the summ it of ~!auna Loa was 

frequently registered in the CO 2 records. It occurred mainly between midnight 

and 0800 LST during t he southerly downslope wind flow regime . Tab l e 2 shows 

the monthly occurrences of outgassing that appear in the C02 records. 

Ozone 

Su rface ozone was measured continuousl y t h ro ughout the year with a Dasib~ 

ozone meter. 

Total ozone in the atmospheric co lumn was measured a t MLO on each of 

approximately 250 days during 1981. In additi on, a specia l series of ozone 

measurements was taken over a 2 -mo period during the s ummer, in response to a 

request from Boul der. 

Surface Aerosol s 

Operation of the G.E. and Pollak CNC's was normal. 

As mentioned in sec . 2.1.1, the fo ur-wavelength nephelometer operated 

reasonably satisfactorily during the first 4 months of 1981, but was inoperable during t he remainder of the year . 

Stratospheric Aerosols--Lidar 

The stratosphe ri c cloud from the eruption of Mt. St . Helens in May 1980 

was still observed over Hawaii t hrougho ut 1981, usi ng lidar. The cloud became 

less pronounced, however, and was difficult to distinguish from the ba ckground 

Junge layer . 

Operati on of the lidar was re liable during t he first and last parts of 

the year, and valuab l e data were taken on a weekly basis, weather permitting, 

7 
from 1 January to 25 March and from 14 October to 31 December. During the 

intervening period, occasional observations were taken, but equipment problems 

prevented a normal schedule. The problems are briefly outlined as follows . 

(1) The Pockels cell fai led on 25 March because of a window fracture due 

to a n air bubble in the ce ll. The spare cell was found to be of the wrong 

type, being designed for "switch off" rather than "switch on" operation of the 

laser. In an attempt to get the old cell (Apollo) repaired, it was learned 

that Apol l o no longer supplies or services this type of cell, so a new cel l, 

ordered from a different supplier, was not delivered until June. 

(2) This new cell was defective, and it failed during the second set of 

observations made with it. Since it was still under warranty, the company 

repaired it without cos t, but observations were de l ayed. 

(3) After the repaired ce ll was i nstalled , its windows were damaged because the laser power density exceeded t he damage threshold of the components. 

The poor condition of the ruby rod was probably the reason for the damage, but 

to forestal l excessive energy output, a laser calorimeter was purchased for 

checki ng energy output. The Pockels cell was again returned to the company 

for repair, and t he ruby rod was repolished. The whole system was again 

operationa l on 14 October, and it operated satisfactorily for the remainder of 

the year. 

Solar Radiation 

Solar radiation observations continued without serious problems in 

1981. tleasurements with OGI and GG22 pyranometers were t e rminated on 27 March 

in response to a request from Boulder. MLO's pyrheliometer and pyranometer 

responses were comp ared with those of circulating reference standard instruments in March and April. An ACR was added to the t!LO complement of instruments in June. A defective filter block on the 13-channel radiometer was 

replaced by a newly recalibrated one in July, and in September the signals 

from radiometer channels 8 , 12, and 13 were put on ICDAS channels 18, 17, and 

20, respectively. 

Meteorology 

t!eteorological measurements continued withput major problems throughou t the yea L. 

Precipitation Chemistry 

Precipitation chemistry and related programs continued normally through 

1981. 

Cooperative Programs 

Most of the cooperative programs listed in table 1 continued through 1981 

without major difficulties. The following items are worthy of special note: 

(1) A. Dittenhoefer, a visitor at MLO under the National Research Counc il 

Associateship program, completed his 18-mo visit to MLO in May and took a new 

position with Enviroplan, Inc ., West Orange, N.J.; (2) equipment from the Max 

Planck Institute, Mainz, Germany, for measuring carbon monoxide fai l ed on 

26 January, and no further measurements were made during 1981; (3) J. Noxon, of 

8 
ERL in Boulder measured NO at MLO during several days in each of the months 

of April, June, and Novemb~r; (4) A. Clarke, of the University of Washington, 

s pent 4 weeks from 23 May to 19 June meas uring the absorption properties of 

aerosols at MLO; (5) aerosol sampling by means of the streaker from Florida 

State University was inde finitely suspended on 22 July, whe n the motor failed 

and no repla cement was available; and (6) in a special program, nine pairs of 

flask samples taken during a 3-wk period in July were sent to R. Rasmussen of 

OGC for ana l yses of their gaseous content. 

2. 1 . 3 ~!auna Loa ~leteorological Museum 

J. Cross, a retired forestry specialist, continued to se rve as a 

volunteer cura t or for the full year. The collection of the mu seum was increased during t he year by t he following items: (1) the slide rule owned a nd 

used for many years by the late H. Wexl e r; ( 2) a wind recorder of the type 

used in mos t weather stations in the United States beginning in the 19 20' s ; 

(3) three boxes of books, pamphlets, tapes, and other materials on met eo rological and astronomical subjects; (4) a rain gage of the weighing-bucke t 

type; and (5) misce llaneous publications on various subje c ts in me teorology 

and related fields. 

2 . 2 Barrow 

2.2. 1 Fa cilities 

WIth t ht:! drasLic reduction of operations at NARL there was great concern 

that the e l ectrical power s uppli ed t o BRW would be dis continued. Several contingency plans were investigated in the event that NARL wa s completely shut 

down. For example, insta llation of a power line from the station to t he 

Dewli ne station was suggested. The estimated cost for hauling a nd sinking 

power poles was ove r $3 0,000. Fortuna tely, it has become increasingly apparent that the USGS , required to maintain power to the local gas fields, will 

most likely opera te the ex i sting power gene rators at NARL and will event ually 

become the administrative agency for NARL. Arrangements are being made for 

t he station to continue to receive power from NARL when the administrative 

transition is made . 

In Septemb er , a 14- x 20-ft Wannigan hut was acquire d from NARL and stationed approxima tely 100 ft no r th of the ma in building. With the addition of 

a garage door, it has become a convenie nt storage area for the s nowmobil e and 

all-terrain vehi c le. 

The access road running from the Dewline s tation to the observa to ry site 

is in need of significant repair. The road requires at lea st another layer of 

gravel and binder fo r it to be crowned a nd smoo thed properly. 

After losing many set'vices f rom NARL, an imprest fund was granted the 

station chief to make modera t e purchases and to facilitate the payment of 

certain services such as the telephone hill. 

Through an i nteragency transfer, a 1979 G~!C pickup truck was obtained 

from NARL. The 1973 International truck was exce ssed, and the Sidewinder allterrain vehi c l e, whi ch has countless problems from a froz en engine block to a 

flooded carbureto r, may be excessed soon. 

9 
2.2.2 Programs 

Programs carried out at BRW are listed in table 3. Comments on some 

selec t ed programs follow. 

Carbon Di oxide 

The URAS analyzer performed well the 'entire year. Heat taping of the 

freezer hose to eliminate fro st buildup ha s been s uccessful. 

A new syst em was initiated 

flasks is sampled in parallel. 

sampling line about 5 ft long, 

the observer . 

Ozone 

for sampling 2-Q flasks outdoors. A pair of 

These flasks are housed in a briefcase with a 

thus minimizing the ris k of contamination from 

There were no major problems with the Dasibi surface ozone meter or the 

Dobson no. 76 spectrophotometer . 

Ha locarbons 

Weekly flask sampling went smoothly. 

Surface Aerosols 

The Pollak CNC and the four-wavelength nephelometer performed well throughout the year. The G.E. CNC had a series of problems from inadequate wiring to 

a flooded casting and was in Boulder for repair for much of the year. 

In December, BRW received a Knollenberg aerosol sprectrometer t o measure 

the size distribution of aerosols. The la ser head was malfunctioning, and the 

instrument was sent back to Boulder f or repair. 

Stratospheri c Aerosols--Lidar 

The lidar system did not f unction properly this year. With its complex 

method of operation, its extensive maintenance requirements, and the less-thanideal location at NARL, t his syst em will apparentl y require a grea t deal of 

attention to be operational. 

Solar Radiation 

Satisfactory solar radiation measurements were taken this year. In 

Harch two of the pyranometers (OGI and GG22) were r emoved and shipped to 

Boulder as requested. The other two pyranometers (QI and RG8) remained in 

operation the entire year . 

Heteorology 

No significant problems were encount ered. A tempera ture gradient system 

was received in December . One temperature probe will be pla ced near the top 

of the meteorological tower, and the other will be installed near the bottom. 

Calibrated together , they will detect any significant t emperature gradient 

near the ground. 

10 
Table 3.--Summary of sampling programs at BRW in 1981 

Program 

Gases 

-----carbon dioxide 

Surface ozone 

Total ozone 

Ha loca rbons 

Aerosols 

Condensation nuc l ei 

Opti cal properties 

Solar Radiation 

Global irradia nc e 

Direct irradiance 

Turbid ity 

Neteorology 

Air temperature 

Soil temperature 

Temperature gradient 

De\<"'point temperature 

Relative humidity 

Pressure 

Wind (speed and direction) 

Precipitation Chemis try 

pH 

Conductivity 

Coopera tive Programs 

Tota l surface particulates (DOE) 

Aerosol chemistry (URI) 

Particulates (Carnegie -Mellon Univ.) 

Particulates (OGC , BNL, NBS) 

Global radiation (SRL) 

Ultraviolet ra diation (Temp le Univ .) 

Ca rbon dioxide (SID) 

Precipitation gage (ASCS) 

Carbonaceous partic l es (LBL ) 

Halocarbons (OGC) 

Incident and reflected radiation 

(Univ. of Al aska) 

Magnetic fields (USGS) 

Ca rbon-I 3 (USGS) 

Instrument 

URAS - 2T infrared analyzer 

O.S - R glass flasks, p3 

0 . 5-R glass fla sks, through analyzer 

5-R evacuated glass flasks 

Dasibi ozone meter 

Dobson spectrophotome ter no. 76 

300-ml st a i nle ss steel flasks 

Polla k CNC 

G.E . CNC 

Four-wave l ength nephe l ome te r 

Eppley pyranometers : Q, RGB 

Eppley pyrheliometer: Q 

Eppley pyrhel iometer: Q, OG l, RG2, RGB 

Sunphotometer with 380- and 500 -run 

narrowband filters 

Thermistor 

Max .-min. thermometers 

Hygrothermograph 

Thermistor 

2 vertically separated t hermistors 

Dewpoi nt hygrome te r 

Hygro the rmograph 

Capacitance transdu ce r 

l1icroba rograph 

uri l barome ter 

Bendix Aerovane 

pH meter (samples ana l yzed at I1LO) 

Co ndu ctivity bridge (sample s analyzed 

at tlLO) 

High- volume sampler 

High- vol ume samplers 

Hi gh volume sampl e r 

High-vol ume sampler 

6 Eppley pyranome t ers 

Ultraviole t radiometer 

5-R evacuated gla ss fla s ks 

Wyoming shiel ded precipitation gage 

Dichotomous sampler 

(qua rtz and Millipore filters) 

High-volume filter 

5-Q stainless stee l fla s ks 

Up -dm,on pyranome t ers 

Magnetometer obse rvatory 

10- R stainless st ee l flasks 

11 

Sampli ng 

frequency 

Cont.inuous 

1 pair ..... k- ) 

1 pai r wk- 1 

Ipa irwk-) 

Co ntinuous 3 day - t 

1 pair wk 1 

Disc rete 

Co ntinuous 

Co nt inuous 

Continuous 

Co ntinuous 

Discrete 

Disc rete 

Co ntinuous 1 day -I 

Co ntinuous 

Continuous 

Co nt inuous 

Co nti nuous 

Co ntinuous 

Co nti nuou s 

Co ntinuous 

Discrete 

Contlnuous 

Discrete 

2 mo- 1 (approx. 

Oct-Hay) 

Co ntinuous ( 1 fil t er ..... k- 1 ) 

Cont inuous (one , 1 filter da y-t; 

the other , on an 

episodi c basi.s) 

Co ntinuous (filter 

expo sed on episodic basis) 

Co ntinuous 

(Jan-Apr) 

Co ntin uous 

Cont in uous 1 pair wk - 1 

2 mo- 1 

Continuous (1 set 

of filters wk - 1 ) 

Co ntinuous (l filter day-I) 

I wk -1 (3 flasks 

sample-I) 

Co ntinuous (program 

ended in Nov) 

sLation check wk- I 

pair mo - I 
Precipitation Chemistry 

Snow s amples were taken twice a month from January to ~Iay and October to 

December. Rain samples were taken on an episodic basis. After accumulating 

several samples, they were mailed to ~ILO for analysis. 

ICDAS 

A new multiplexer was installed in January. The entire system performed 

excellently. There was less than 2% downtime for the entire year . 

Cooperative Programs 

A program to measure 13C began this year for the USGS. A pa ir of sampling tanks, used to store ambient air once a month, were sent to De nver for 

analysis. It was soon dis covered that water was condensing inside the tanks. 

It was speculated that this condensation was forming during the sampling 

period. To remedy this situation the tanks were warmed by a torch during the 

sampling period. 

Carnegie-Mellon University began a filter program of measuring particulates on an episodic basis when the air was coming from the Clean Air Sector 

(free of any local contamination sources such as the town of Barrow or the 

town dump). 

Checking of the unattended USGS ma gnetometer site, l ocated approximately 

500 ft west of the station, was begun once a week. The date and time were 

r outinely l ogged on the chart records, various e lectrica l values were recorded, 

and any significant malfunctions were to be reported to the USGS offic~ in 

Fairbanks. 

LBL modified its carbon particulate sampling program by (1) adding a 

dichotomous filter sampler that uses two quartz and two Millipore filters, 

(2) moving the high-volume filter system indoors, and (3) eliminating the snow 

samples. 

The precipitation gage sampling program included checking the gage at BRW 

and at the village of Atkasuk, about 60 mi south of Barrow. These monthly 

visits to Atkasuk were discontinued indefinitely to save observer time for 

work at BRW. An agreement ha s been made whereby the local school in Atkasuk 

will take the responsibility for chec king the gage and will be reimbursed for 

its services by the state Soil Conservation Service. 

2.3 Samoa 

2.3.1 Facilities 

No additions to SMO facilities were made by mICC during 1981, but completion of the SEAREX project (discussed in sec 5.6) in August r es ulted in some 

additions . Specifica lly, the structures used for the SEAREX operation were 

retained with t he exception of one, which was dismantled. Four small buildings remain, three located at the base of the stairs to Matatula Point and one 

on the ridge, adjacent to the mICC remote sampling tower. 

l2 
The orginal sampling tower at ~!atatula Point consisted of two GMCC sections and two sections belonging to R. Duce . The SEAREX project shipped in 15 

additional sections and constructed a 10-section tower and a 7-section tower 

using t he 2 sections belonging to Duce. When SEAREX was completed, 19 sections were shipped to New Zealand for the 1983 SEAREX operation; thus G~!CC was 

able to construct a 5-section tower at t he point. This tower is the primary 

sampling platform for the G~!CC CO 2 program. The continuous ana l yzer sample 

line is mounted on the tower, and all CO2 flask samples are obtained from the 

top level. 

Additionally, the special high-voltage powerline stepdown transformer 

installed to provide power to the SEAREX operation at the point was not 

r emoved. The line was buried and the stepdown transformer was left in place 

in one of the remaining SEAREX buildings. This provides a valuable asset for 

possibl e future operations at the point, as a result of the increased electrical power capacit y. 

2.3.2 Programs 

All 1980 programs are sun@arized in table 4. Additional comments follow. 

Carbon Dioxide 

The URAS-2T analyzer operated reliab l y all year, and the only equipment 

change involved installation of a new Hewlett-Packard chart recorder during 

February. An improved moisture remova l system for the air line was i nstalled 

du ring February when the condensation trap system in use since February 1978 

was replaced by a freezeout trap assembly cooled by a CryoCool model CC I00F . 

The freezer system is installed at the point, near the sampling tower, and 

it removes nearly all the water from sampl e air prior to passage through the 

l ong sampl e line to the analyzer . The Cinci nnati Sub -Zero unit remained operational as an added protective trap system. 

During June, a major modification occurred when S~!O switched to CO 2-inair reference gases during a visit by W. Komhyr and L. Waterman. Extensive 

testing of the CO 2 air sampling l i ne was also conducted, using a large 

gas-sampling syringe that was fill ed at the point and carried back to the 

ana l yzer. The air sample was then injected through the Cincinna ti Sub-Zero 

freezer system into the analyzer . Differences in CO 2 concentrations between 

air sampl ed by the syringe and air that had passed through the air sampl e line 

from the point were negligib le . During Septemb er, a GMCC-SIO flask comparison 

p rogram began . Weekly GMCC 0.5-1 and 5-1 flasks plus SIO 5-1 flasks are exposed at the point. GMCC semiweekly sampling was terminated with the onset of 

the intercomparison. 

Ozone 

Concurrent operation of the Dasibi and ECC sensors was continued until 

August, when the ECC program was terminated and the sensor was returned permanently to Boulder. The Dasibi ozone meter then became the primary surface 

ozone monitor . 

A regular Dobson observational schedule was maintained all year, and no 

problems with the instrument (no. 42) were experienced . 

13 
Table 4.--Summary of sampling programs at SMO in 1981 

Program 

Gases 

Carbon dioxide 

Surface ozone 

Tota l ozone 

Halocarbons 

Aerosols 

Conde nsation nuclei 

Optical proporties 

Solar Radiation 

Global irradiance 

Direct irradian~e 

Turb idity 

~leteorology 

Air temperature 

Soil temperature 

Dewpoint temperature 

Relative humidity 

Pressure 

Wind (speed and direction) 

Precipitation 

PreCipitation chemistry 

pH 

Conductivity 

Cooperative Programs 

Carbon dioxide (510) 

ALE project: CFC-ll, CFC-12 , 

N,O, CHC1" CC1, (OGC) 

CH" CO, CO, (OGC) 

CH 3 I, CH3Cl) CH 4 , CO (OGC) 

Carbon-13 (USGS) 

Wet-dry deposition (NADP) 

Wet-dry deposition (EML) 

Bulk deposition (ENL) 

Instrument 

URAS-2T infrared analyzer 

0.5-£ glass flasks, p3 

0.5-2 glass flasks, through analyzer 

5-£ evacuated glass flasks 

Dasibi ozone meter 

ECC meter (terminated Sep 81) 

Dobson spectrophotometer no. 42 

30D-ml stainless steel flasks 

Pollak CNC 

G.E. CNC 

Four-wavelength nephelometer 

Eppley pyranometers: Q, RG8 

Eppley pyranometers (two); Q, on 

tilted mounts 

Eppley pyrheliometer: Q 

Eppley pyrheliome ter: Q, OGl, RG2, RGB 

Sunphotometer with 380- and SOD-om 

narrowband filters 

Thermistor 

Max.-min. thermometers 

Hygrothermograph 

Thermistor 

Dewpoint hygrometer 

Hygrothermograph 

Sling psychrometer 

Capacitance transduce r 

Microbarograph 

Mercurial barometer 

Bendix Aerova ne 

Polyethylene funnel, bottle 

Corning model 125 meter with 

semimicro combination electrode 

Beckman model RC-16C meter 

5-Q evacuated glass flasks 

HP5840A gas chromatograph 

Carle gas chromatograph 

Stainless steel flasks, 3 set- 1 

10-£ stainless steel flasks 

HASL we t-dry collector (new 

Cheme trics, Dec 81) 

HASL wet-dry collector (terminated 

Nay 81) 

Plastic bucket 

14 

Sampling 

frequency 

Continuous 

pair wk- 1 

1 pair wk-] 

1 pair wk- 1 

Continuous 

Continuous 

3 day - 1 

1 pair wk-] 

Discrete 

Co ntinuou s 

Cont inuous 

Continuous 

Continuous 

Continuous 

Discrete 

Discrete 

Continuous 

1 day-l 

Continuous 

Continuous 

Co ntinuous 

Con tinuous 

Discrete 

Continuous 

Continuous 

Discrete 

Continuous 

3 

I 

2 

day-l 

day -, (G~IC C); 

I wk -, (NADP) 

day-' (mICC); 

I wk -, (NADP) 

pair 

h -, wk- t 

h-' 

wk- 1 

pair mo- 1 

wk-] ~ wet; 

2 mo 1, dry 100- 1 

rno -1 
Surface Aerosols 

The G.E. CNC operated all year with the exception of approximately a 1-mo 

period from late tlarch to late April when the instrument was in Boulder for 

repair . 

After an 18-mo absence from SMO, the four-wavelength nephelometer was returned and went back online 14 tlarch. While in the United States, the instrument was fitted with a photomultiplier tube that does not require cooling. A 

marked improvement in instrument performance and reliability resulted. 

Solar Radiation 

During March, the GG22 and OG1 pyranometers were taken offline and 

returned to Boulder. Of the two pyranometers that remained in operation, the 

RG8 pyranometer was replaced in May because of a stained dome, and the quartz 

unit was exchanged in December after a systematic drift in the original SMO 

instrument calibration was discovered. 

The GHCC traveling standard pyranometer and filter wheel pyrheliometer 

were intercompared during June and July . • 

Heteorology 

The Aerovane was repla ced in May . During September, a thre e-comp onent 

anemometer was installed by G. Herbert, while on a station visit . 

Precipitation Chemistry 

Three collection protocols were maintained : (1) GMCC daily collections 

(bulk), (2) NADP we ekly co llection of wet deposition, and (3) EML monthly bulk 

collection. 

Onsite measurements of pH and conductivity were performed on mlcc and 

NADP samples . 

ICDAS 

The data acquisition system operated routinely all year. Immunity to 

island power outages and fluctuations was significantly increased in July when 

the ICDAS UPS was modified to operate at 60 Hz by use of an internal quartz 

frequency source rather than the previous phase-locked loop method that 

tracked the island line frequency. 

Cooperative Programs 

The gas chromatograph from R. Rasmussen's ALE proj ect at OGC was operational all year . A UPS was installed during May to eliminate disruptions 

ca used by power outages. The Carle gas chroma togr ap h was offline from 

1 October through the end of the year . Weekly flask samples were collected 

for OGe all year. 

SEAREX, a comprehensive program for meas urement of sea-air exchange processes, was operational during January, February, June, July, and August 1981 . 

All materials and equipment were then returned to the United States or shipped 

15 
to New Zealand for scheduled 1983 activity there. Details of SEAREX are discussed in sec. 5.6. 

2.4 South Pole 

2.4 .1 Facilities 

spa conti nued operations for the 1981 season wi th few problems a nd little 

downtime in the CAF. There were some modifications made to the internal and 

roof layouts of the CAF; figs . 1 and 2 illustrate the new layouts. The GMCC 

Summary Report for 1978 (Me ndonca, 19 79 , figs . 3 a nd 4) s hows the old layouts. 

The changes made inside we r e (1) the removal of SIO CO 2 flasks from the storage cabine t, (2) the pl acement of the surface ozone equipment in a separate 

rack, and (3) the removal of WPL equipment and racks from the so l ar radiation 

room. These a rra ngements allowed for more storage space for spa programs, and 

improved the e nvironme nt for the surfa ce ozone instruments. The electric 

field mill (removed 7 Decemb er 1980), the UV radiometer (disco ntinued), and 

the GG22 pyra nometer (dis continued) no longer reside on the CAF roof. The 

University of Maryland' s Atmospheric Chemistry Program (cooperative program) 

reduced the height of their three high-volume sampling stacks by 3-5 ft. The 

remova l of the elec tri c field mill and shortening of the samp ling stacks may 

have reduced the amount of so l ar radiation data lost because of s hadow in t erfere nce. 

Figure 3 shows the general layout of spa and the area proposed by GMCC to 

NSF as the Cl ean Air Sector. Questions concerni ng the exact boundaries of the 

sect or arose during the year. Specifi ca l ly GMCC proposed that a Clea n Air 

Sector be maintained upwind of t he station, between 330 0 and 1100 grid, and 

suggest ed if possible that no structures be installed i n the sector. Fu rther, 

the Science Sector between 1100 and 1500 should be maintained far enough upwind of the station t o e liminate the possibility of detection of pollutants 

from t emporary structures for scientifi c studies. Portabl e gene r a tors s hould 

not be placed in the Science Sector. 

Measurements for both the Clean Air and Science Sectors begi n at the grid 

NW corner of the CAF. During a ustral summer , airc raft ac tivity ext e nds i nto 

t he Clean Air Sec tor. Al lowa nces can a l so be made for temporary s pecial proj ects that may require the use of the Clean Air Sector or Science Sector. 

Electrical power t o the CAF was adeq uate . In July 1981, two new e l ectrica l outlets were installed near t he sampling st ack to resolve the e l ectrica l 

problem of overloaded circuits from additional equipment. 

The GMCC sampling st ack did not require interna l clea ning. A heat l amp 

was installed to alleviate ice buildup along the outer portion of the stack 

inside the CAF. The lamp, capable of being raised or l owered, slowl y melted 

t he ice without causing dama ge to the stack or affecting t he air being sampled. 

In previous years, use of a heat gun, blow torch, hammer , and screwdriver was 

the method for melting or chipping the ice from t he s t ack. 

TW0 static ma ts, placed in front of and behind the ICDAS racks, and a 

humidifier were used throughout the year to suppress static discharge . 

The first spa air drop occurred on 22 June. 

16 
Moisture 

Monitor 

co, Tanks 

Cryocool 

File 

Sampling 

Stacks 

Pollak 

....--Grld North 

File 

(] 

ooks 

Hi-Vol Pumps 

Univ. of Marylan 

GMCC Cooperative 

Repair 

Bench 

Common 

Storage 

Fgl~~~g GMT~~k~02 

Co ff e-::e:.LJ In-='. 

\ 

Shelves 

Porch 

Dobson 

~ 

Shelves Solar 

Radiation 

D Room 

(NOAAI 

GMCC) 

FW NIP 

= 

Figure 1.--Interior plan of CAF at sPa, 1981. 

>----------17.1 m-----------

t:@ 000 0 

GMCC Univ. of Maryland [] D 

Sampling Stacks Air Sampling Stacks DOEIEML Dobson Hatch 

Pump Enclosure 

7 .6 m 

Pyranometers 

RG NWS NIP 

0 I !Jill I I 0 

OG a 

-Grid North 

111111111111 II 

Figure 2 . --Roof plan of CAF at sPa, 1981. 

17 

Dobson Room 

(NOAAlGMCC) 
Grid North 

~~O. 

!pr:valiing Wind 

Fuel Arch 

Biomed Arch 

Main Entrance 

Generator Arch 

Garage Arch 

To Summercamp 

'\ 

Geodesic 

Dome 

330· 

\ 

" \ Clean Ai r Sector 

GMCC 

~_.Met. Tower 

30.5 m~.snow Temp. 

lf1New CAF 

IT, r91.5 m I \(Science ........ A I Sector ........ Uo·1 \ Old CAF I [](unde~round) 

I Met. Tower\ 

I \ 

I \ Skylab 

I \ 

Snow Pit I 

(Water Supply) I 

........ 110 · ...... 

Figure 3.--Amundsen-Scott Station at South Pole, 1981. 

2.4.2 Programs 

SPO programs for 1981 are listed in table 5 and are briefly described 

below. 

Carbon Dioxide 

The CO 2 program operated well all season. The intercalibration of 

nitrogen and air standards was conducted as instructed on 3-5 December and 

26-27 December 1980. The lid of the U-Tainer cold bath was redesigned 

10 February to allow easier access to the thermometer and water traps. In 

earl y April a heat lamp was installed on the bench in front of the CryoCool 

unit to eliminate an ice buildup problem around the cryogenic probe. A precision drive for the chopper motor was installed 18 June to improve data 

quality and to eliminate the glitches believed to be caused by powerline frequency instability. 

Discrete flask samples were alternately taken on the CAF roof and through 

the analyzer system until 16 April. The sampling sequence then changed to 

roof, analyzer, ground, analyzer, roof. The p3 unit arrived at SPO on the air 

drop and was in operation 21 July. The sampling sequence was changed to roof, 

ground, analyzer, roof . 

Zero drift occurred during the year as in previous years. It is believed 

to be temperature-induced, the main trouble source being the Chroma lox heater 

18 
Table 5.--Summary of sampling programs at SPO in 1981 

Program 

Gases 

--carbon dioxide 

Surface ozone 

Total ozone 

lIalocarbons 

Aerosols 

Condensation nuclei 

Optical properties 

Solar radiation 

Global irradiance 

Direct irradiance 

Turbidity 

Heteorology 

Air temperature 

Snow temperature 

Room temperature 

Water vapor density 

Pressure 

Wind (speed and direction) 

Cooperative Programs 

Instrument 

URAS-2T infrared analyzer 

0.5-t glass fla s ks, pl 

0.5-£ glass flasks. through analyzer 

Dasibi ozone meter 

Dobson spectrophotometer no. 83 

300-011 stainless steel flasks 

Pollak CNC 

G.E. CNC 

Four-..... avelength nephelometer 

Epp l ey pyranometers: Q, OGI. RGB 

Eppley pyrheliometers: Q, RGB 

Eppley pyrheliometer: Q, OGl , RG2, RG8 

Sunphotometer with 380- and 500-nm 

nano,,"'band filters 

Thermistor 

Thermistor 

Thermistor 

Du Pont 303 moisture monitor 

Capacitance transducer 

~1i cr(')ha rograph 

~lercurial baromeler 

Bendix Aerovane 

Carbon dioxide (SID) 5-{ evacuat ed glass flasks 

Total surface particulates High-volume sampler 

(DOE) 

Total surface particulates High-volume sampler 

(EPA) 

Aerosol chemistry (Univ. 

of Iar yla nd ) 

Aerosol chemistry (URI) 

Halocarbons (OGC) 

Carbon-13 (USGS) 

High-volume samplers 

iligh-volume samplers 

5 - £ stainless steel flasks 

10-£ stainless sleel cylinder 

Sampling 

frequency 

Continuous 

Ipairwk- 1 

I pair wk- j 

Continuous 

3 day-j 

pair ..... k- I 

pair ..... k- 1 • 

austral summer 

pair mo- I 

austral winter 

Discrete 

Continuolls 

Continuous 

Continuous 

Continllolls 

Discrete 

Discrete 

Continuous 

Continuous 

Continuous 

Continuous 

Continuous 

Continuous 

Discrete 

Continuous 

2 mo - I (3 flasks 

sample-I) 

Continuolls 

(l filter wk- I ) 

Continuous 

(l fil ter ,,"'k- 1 ) 

Continuous 

Continuous 

3 summer-I 

(3 flasks 

sample -I) 

Discrete 

Remarks 

Jan 74-present 

(excl. Nov 78-

Nov 79) 

JU" BI-present 

Nov 79 - present 

J," 76-present 

Dec 63 -present 

J," 77-Dec 79 

J," SO-present 

Jan SO-present 

Jan 74-present 

Ja n 74-present 

Jan 79-Dec 79 

Jan SI-Dec 81 

Feb 74-present 

Oct 75 -present 

Jan 77-present 

Jan 74 -presen t 

~la r 77 -present 

tla r 77-present 

Jul 7S-present 

~lar 77-present 

Dec 75-present 

Feb SO-present 

J," SO-present 

Dec 75-present 

1957-present 

~Iay 70-present 

la y 70-present 

Jan 79-present 

Jan 79-present 

1980-present 

Jan BI - present 

behind the analyzer. Therefore a cardboard partition was placed between the 

analyzer a nd the heater earl y in the season, and a suggestion was made to the 

incoming crew to move the heater. 

Ozone 

Operation of the surface ozone program continued, with the addition of a 

Dasibi 1323 as the sta ndard instrument. The Dasibi 1323 and the Mec-1000 

ozone generator no . 205 were installed and onl ine 17 December 1980. A new 

Watanabe Hicroservo recorder was installed on 20 January to replace the 

Rustrak recorder . 

19 
The Dasibi 1316 was tranferred to its own rack from the G.E. CNC rack on 

18 September to corr ect for a high instrument t emp era ture of about 40°C. 

Surface Aerosols 

The Pol l ak CNC operated well all year. The G.E. CNC was sent to Boulder 

for repair 10 Novemb er and returned to SPO and online 29 De cember 1980 . It 

went down again 8 October 1981 and was returned to Boulder for repair. 

The four-wave l e ngth nephelometer obtained good results from January to 

December 1981 . It arrived at SPO with minor damage from shipment and was 

online 28 January. 

Solar Radiation 

The quartz standard intercomparison using quartz secondary standard no . 

12562 was conduc t e d from 15 January to 5 February. Starting 19 September 

1981, the GG22 pyranometer and the UV radiometer were discontinued. 

Meteoro l ogy 

There were no ma jor problems with the meteoro logy program except the 

Du Pont 303 moisture monitor. The data from the moisture monitor are questionable. There were p roblems with the ce lls and difficulties in regul ating 

the flow rate. 

On 15 January the radiation shie l d was installed on the temperature 

sen sor unit . 

ICDAS 

The NOVA 1220 wa s replaced with a newer NOVA 1220 on 9 Janua ry . Because 

of unrepairable mechani cal parts , the teletype was replaced 13 May with a 

spare unit from the st a tion Meteorology Office . All other ICDAS-related 

equipment operated continuously all year wi thout difficulty. 

20 
3. CONTINUING GtICC PROGRAl'IS 

3.1 Carbon Dioxide 

3.1 . 1 Analyzer CO 2 Mea s ur ements 

CO 2 meas urements made wi th continuously operating NDIR gas analyzers were 

continued during 1981 at the four GtICC stations (BRW, MLO, SMO, and SPO). 

Data acquisition and processing procedures remained identical to those described in GtICC Summary Reports for 1977 and 1978 (Peterson, 1978; Mendonca, 

1979 ) . The compl e te re cord of continuous mea s urements at the four s tations 

through 1981 is presented i n table 6, in the form of provisional monthly mean 

CO 2 mole fractions, and plotted in fig. 4. These values, expressed in the 

provisional ~IO 1974 CO 2 -in- a ir mole fraction sca le, are preliminary . Final 

values incorporating the best de t ermina tion of carrier gas effects and final 

working-standard gas concentrations s hould be available earl y in 1983 for the 

full continuous r ecord at each of the stations. Relative errors in the provisional values (table 6) are genera lly estimated to be less than 1 ppm, except for the firs t 3 years at BRW and occasional parts of the SPO re co rd where 

press ure-broadening corrections have been made with l ess certainty, and at SMO 

where portions of the r eco rd require editing because of occurrences of sample 

l i ne contamination. The questionable SMO data occurred from mid-October 1977 

t o earl y February 1978 a nd from mid-Octobe r 1978 to early February 1979 . Systematic errors are believed to be less tha n ±1 ppm relative t o a n absolute CO 2 

mol e fract ion scale. The provisional values of table 6 are a subset of the 

full record and have been selected to e liminate unreliable data resulting from 

meas urement problems and to e limina t e highly va riable data that are probably 

r epresenta t ive of l ocal pollution . 

Table 6. --Provisiona l monthly mea n CO 2 fra c tions (ppm) 

for BRW, ~ILO, S~!O , and SPO 

Yeu ,,, F.b Hn Ap' H.y ,,, "I A,S S.p 0« No. Do< 

BRO 

1973 324.4 322.6 325.6 330.3 334. I 334.4 

1974 338.2 336.8 331.5 338.8 337.J 336.4 331.0 325. I 325.8 330.1 333.3 336.3 

1975 338.3 340.6 338.8 338.4 339.2 336.3 328.8 324.6 325.8 329.7 335.3 336.8 

1976 337 .4 331.8 338.7 339.0 338.2 331.\ 331.3 323.6 325. 1 330.0 334.1 336.4 

1977 336.7 336.7 338.1 339.0 339.2 331. 7 330. I 326. I 321. 9 331.6 334.1 338.8 

1978 339.3 )40.0 341.7 341.0 342.1 339.6 332.4 328.1 328.4 331.8 338.1 338.5 

1979 339.0 340.3 341.6 341 .4 34] .9 340.9 332.3 327. 2 329.2 332.3 337.5 340.4 

1980 34\.0 341 . 1 342.9 343.5 343.1 341.9 336.5 331.7 331.3 331.9 340.4 342.8 

1981 343.3 344.6 343.7 345. I 346.1 343.6 336.2 331. 1 333.0 337.8 340.3 343.9 

H10 

1974 332.9 331.7 330.5 328.5 326.9 326.8 327.9 329.3 

19 75 330.4 331.2 331.8 332.9 333 .6 333.0 331.3 329.4 328.0 328.0 328.9 329.2 

19 76 331.3 332.3 333.1 334.4 334.5 334.0 332.1 330 .1 328.4 328.3 329.9 331.4 

1917 332.4 332.8 334.6 335.8 336 .5 336.0 334. 1 332.1 330.7 330.9 332.2 333.5 

1978 334.6 335.0 336.3 337.5 337.8 337. 6 335.9 334. I 33 1.8 332.0 333.4 334 .7 

1919 335.8 336 .3 331.5 338.6 338.5 338.8 337. 2 335.2 333.7 334.0 334.9 336.1 

1980 337.4 337.9 339.5 340 .3 341.0 340.8 338.7 336.8 335.1 335.2 336.4 337 .5 

1981 338.6 340.1 341.3 342.1 342 .6 342.2 340.0 338.0 336.6 336.8 338.4 339 .6 

5110 

)916 333 . 5 333. 1 332.6 332.5 331.8 332.3 332.1 332.4 332.6 332 . 7 333.1 333.1 

1977 333.1 332.1 333.5 333.4 334 .0 334.9 334.4 334.3 334.1 335.3 335.4 336.7 

1978 337 . 8 335.4 335.6 335.8 335. 5 ]]5.7 335 . 3 335.8 337.3 338.3 338.2 339.2 

1979 340.6 335.8 336.5 335.9 336.2 336.7 336.6 336.6 336 .9 337.0 337.2 

1980 337.9 337.9 338.2 337.5 338.0 338.2 338.1 337.6 337.5 337 . 4 337.8 338.4 

1981 338.7 339.0 338.3 339.1 338.' 339 .1 338.9 339.0 339 .0 338 .7 339. 1 339.5 

SI'Q 

1975 329.8 329.8 329 . 8 329.' 329. I 329.7 330.5 331.2 331.6 331.9 331.1 330.0 

1916 329.7 329.5 329.3 329.3 329.3 329.5 329.9 330.4 331.0 331. I 331.2 33 1.1 

1977 330.6 331.5 331.3 331.' 331. 4 331.6 331. 9 332.3 332.6 333.0 333.0 332.6 

1978 332.3 332.5 333.1 333.6 333 .6 334.1 33' .Io 335.2 335.9 335.9 335.7 

1979 

1980 335.7 335.5 335 . 6 335.4 335. 5 335.9 336.' 336.7 336.9 337.5 337.5 336.6 

1981 337.3 337.2 337 . 3 337.3 337. 5 337.8 338.1 338.3 338 .6 338.4 338.2 337 .7 

21 
~ 

0... 

0... 

0'" 

(.) 

350 

-BRW 

0 c MLO 

345 -SMO 

0 o SPO 

340 

335 

330 

325 

320L-1-97-3~--19-7-4-L-1-97-5~--19-7-6-L-9-7-7-L-1-9-7-8-L-19-7-9-L-1-9~80~--19-8-1~ 

Year 

Figure 4.--Provisional monthly mean CO. mole fractions for GMCC observatories. 

3.1.2 Flask Sample CO 2 Measurements 

The GMCC CO 2 flask sampling program was expanded in 1981 to 20 stations, 

with startup sampling at Ocean Station M (66°N 02°E) and at Port Stanley, 

Falkland Islands (51°42'S 57°52'W). All stations active in 1981 are listed in 

the mlcc Summary Report for 1980 (DeLuisi, 1981, p. 20), with detailed station 

information (coordinates, elevation, and cooperating institutions and countries) given in the GMCC Summary Report for 1979 (Herbert, 1980, p. 19). 

The edited flask data for 1979-1981 are presented in fig. 5 for the 20 

flask stations in order of decreasing latitude. The data have been tightly 

edited for background cond itions. Large portions of the period of severe contamination in 1979-1980 have been omitted entirely. The pair agreement criterion was chosen at 51 ppm. The record has also been scrutinized for large 

year-to-year changes in the seasonal pattern resulting from sample degradation 

due to long storage or from problems at the time of analysis. Occasional outlying values ($2% of the data), although probably representing valid atmospheric concentrations, have been reje c ted from the selected set as not representative of background conditions. They were generally more than five standard deviations from the envelope of the selected data, as approximated by the 

dotted lines in fig. 5. 

Edited in the manner described, the 3-yr flask record at most stations 

reveals a stab le and characteristic seasona l pattern superimposed on a percept i ble seculaE growth rate of - 1.4 ppm yr- ' The fastest rate of CO 2 increase 

(- 1.5 ppm yr 1) is found at midlatitude s of the Northern Hemisphere, which i s 

22 
::;; 

DDZ 

345 

340 

335 

330 

325 

345 

340 

335 

330 

a 325 

~ LL 

w 345 -.J 

§i 340 

ON 335 

U 

330 

325 

345 

340 

335 

330 

325 

Mould Bay 

Barrow 

1979 

76N 11 9W I 

71N 156W 

1980 

Station M 66N 002E 

;~'~:, ,I.!~: ~ .. 

"" ~. 

, 

1981 

-ti' " 

~-"--\~ ~ 

i! ot'" .... , . 

Figure 5.--Edited CO 2 flask data f or 1979-1981 at 20 st ations. Values 

are presented in the 1974 wtlO CO2 -in-air mole fraction scale. The symbol x represents a reliable paired value; the symbol a represents a lessreliable, generally unpai red value. The dotted lines represent handdrawn estimates of the envelope of the data, selec t ed for background 

conditions. 

consistent with the l ocation of fossil fuel sources; significantly lower va lues (- 1.2 ppm yr-') are observed f or midl atitudes of the Southern Hemisphere. 

The latitude dependence of the seasonal amplitude (fig. 6) reveals a maximum (-16 ppm) at high northern l atitudes (- 600 N) that is an order of magnitude greater than the mean f or the Southern Hemisphere (-1.5 ppm). There is a 

clear indication of a stronger CO 2 seasonality at t he Antarctic ice edge 

(2 ppm at Palmer Station, 65°S) than at the South Pole (1 .5 ppm). In fig . 6, 

values for ~!LO (20 0 N, elev. 3400 m), NWR (40 0 N, 3750 m), Point Six tlountain 

(47°N , 2500 m) , Azores ( 39°N 27°W, sea level, North Atlantic) , and Station tI 

23 
5 

f= 

u 

<1 

Ct: 

lL 

W 

-' o 

::< 

0'" 

u 

345 

340 "I 

335 

330 -

. '. "' i 0 • ,," ... . ..... ...····· ·· ~ 

.. f 

... •f, ..•..•. ·.·. ~f ./...... . ......... ! 0, ' 0;;./' // ......... ~ .. .:. <?.. .. ...... 0. ...... .... 

0'" 

' . 

325 t Point Six Mt. 47N 11 4W 

r.-'~rT-''-rT-'~~~~~~~~'-~-''-''-''-~-''-~ 

345 

340 

335 

330 

325 

345 

340 

335 

330 

325 

345 

340 

335 

330 

325 

\ 0

1 

.. 

Niwot Ridge 40N I06W 

Azores 39N 027W 

" '0" 

~~~~~ •. ~:~ "' ~~ . ,.-0 .. .. .... . .•.. . • •.• ,," ~ ••. 

'.~ ". "" ·· .I · .... 

... ..... , .... 

·· .... 0": ... . 

Key Biscayne 26N 080W 

, , 

1979 1960 

, .Q •• '."0' ....... . 

.. . .•.• ··l '· , .( •.•. .0. ... . . 

··· ········i ···· 

. ............. . 

1961 

Figure 5 .--Edited CO 2 flask data for 1979-1981 at 20 stations--Continued. 

(66°N 02°E, sea l evel, North Atlantic) have been plotted with a different symbol (0) for comp arison, but. we re not include d in the fourth-order polynomial 

fit (smooth curve ) to the data (*). Stations a t higher elevations or very 

di fferent longitudes (0) have smaller CO 2 sea sonal amplitude s. The lower amplitudes at Azo r es and Station M in the No rth Atlantic suggest an ocean seasonality of -2 ppm worki ng out of phase with the dominant land biosphere seasonali t y at t hese l atitude s. Weathership Papa (P) data are plotte d for comparison. The seas ona l ity for a sea level, midl a titude northe rn station will 

be available next yea r with startup data from Cape ares, Ore . 

Although the sea sonal variations at s evera l stations (Fa lklands, Cosmos, 

Key Biscayne , Azores, NWR, Point Six Mountain) a r e not yet well characterized, 

t he full set of 20 sta tions reporting in 1981 may be synthesized to give a 

fair representation of the global CO 2 sea s onality. Figure 7 presents a three -

dimensional pe r spec tive on the global 1981 CO 2 distribution. Although some 

24 
::;; 

(L 

(L 

z 

o 

i= 

~ 0:: 

LL 

W 

-.J 

o 

::;; 

ON 

<..> 

345 

345 

340 

335 

330 

325 

345 

340 

335 

330 

325 

345 

340 

335 

330 

325 

Cape Kumukahi 20N 155W 

Mauna Lao 20N 156W 

.;J;JiM..... ,,' . y:,·····'··,··:.\1oi .,. .. , .... '\. . "' . .. .•.. ~ . . l .l. , " ," .. 

SI. Craix 

Guam 

" , 1979 1980 

18N 065W 

13N 145E 

, 

1981 

Figure 5.--Edited CO 2 fla s k data for 1979-1981 at 20 stations--Continued. 

residual local bumpine ss reflects the need for additional editing of outlying 

value s , the major features of the global distribution are clear, especially 

the dominance of the Northern Hemisphere, high-latitude drawdown of CO 2 in 

l ate s ummer . This northern seasonality is transported across the equator to 

15°-200 S. The " zero-phase" l a titude, or e ffective equator for CO 2 seasonality 

is a flat trough a t 15°-300 S. The most pronounced southern seasonality is in 

the l a titude band 50 0 -70 0 S (Falklands to Palmer Station), and ma y well be related to seasonal variation of sea-ice cover and upwelling-downwelling in the 

Anta rc tic circumpolar current. Removing stations that are not at sea l evel 

and those in the Northern Hemisphere at very disparate longitudes woul d certa inly smooth the Northe rn Hemisphere patte rn. The secular increase ha s not 

been removed, so each latitude strip tends upward by -1.3 ppm over the l -yr 

timespan . 

To i mp rove the quality of flask samples collected for CO 2 ana lyses , several i mportant change s were made during 1981 in the sampling methodology. 

25 
~ CL 

Z 

o 

~ W 

..J 

~ 

d" 

u 

345 

340 

335 

330 

325 

345 

340 

335 

330 

325 

345 

340 

335 

330 

325 

345 

340 

335 

330 

325 

Seychelles 0 5S 055E , , , , , , , 

Ascension 08S 014W 

. ...... . 

,"""j;Ii;; '. • .. :,;~ \..'''' ..•. ; .

..... . ..... ". 4 ° 1 ".:p" " ....• , ....•. _ ..... ' . ..,. . ". 

.... .. .... /~. 

Cosmos 12S 075W 

............................ ·;,;,;;a··!:Ah·· ,y; . . ....... ,." ...... ;.1; 

···· ·· r' ~ ..... ftIuIJ.:~~.,H' fo-··· ·· "'i j·~· ~'I'\~ .. ~ ... :'!' ~ •. ~"' ·· ""'·~f""' :"'-- fIIolI! ' "....... . 

Samoa 15S 171W 

1979 1980 1981 

Figure 5.--Edited CO 2 fla s k data f or 1979- 1981 at 20 stations--Continued. 

First, following the discove ry that many of the gla ss flasks containe d a powdery residue resulting from decomposition of t races of silicone greas e during 

heat treating of the flasks, a p rogram was initiated to reclean all fla s ks 

with an aqueous so lution of hydrofluori c acid. Second, the method of flask 

preparation was changed from silicone-greased stop coc ks a nd evacuated fla s ks 

to Apiezon-greased stopcocks and flasks i nitially evacuated and then fill e d t o 

a slight positive pressure with a low-C0 2 reference gas prior to shipment t o 

the s ampling stations. Also in 198 1, a small portable air-pumping syst em, p3 , 

was developed, tested, and dep l oyed t o a ll 20 sta tions . The system i s us e d t o 

collect pairs of air sample s simultaneous l y in se ries in 0 .5-Q glass fl as ks 

that are pressurized to approximately 1 . 3 atm . Introduction of the p3 system 

dramatically improved pair sampl e agreement a t most stations. 

A milestone was reached in June 1981 when CO 2 -in-N2 ca libration gases 

were replaced at MLO and SMO with CO 2 -in-air calibration gases. Use of 

CO 2 -in-N2 had been discontinued in the GMCC flask samp ling p rogram in January 

26 
345 

340 

335 

330 

315 

345 

340 

~ 335 

CL 

z 

o 

f= 

u 

« 

a:: 

lL 

330 

315 

w 345 --' o 

::ii 340 

ON 335 

U 

330 

315 

345 

f#A~:. ./j+. ~~:~t;o.·:~·~~~~.· ~~ o 

Amsterdam 38S 078E 

Falkland 52S 058W 

Palmer Station 65S 046W 

, 

340 ,«".-, .. " .• . v ...... ",-o ··· l" lOli J,0"N' 'l'f.·· ·:-! 

335 :.~~<fj . !I\I\~66· 4·, :::::.'~: p~ :1.·· ,, ~: iA :iX.KA~: .... ... . 

330 

315 South Pole 90S 025W 

1979 1980 1981 

Figure 5.--Edited CO 2 flask data f or 1979-1981 at 20 stations--Continued. 

1979, and conversion to use of CO 2 -in-air was made at BRW and SPO during 

middl e and l ate 19 80, respectively . The us e of CO 2 -in-air calibration gase s 

eliminates the need to apply co llision-broadening corrections to CO 2 data. 

As a check on CO 2 flask sample data qual ity , several CO 2 data comparison 

programs were initiated in 198 1 (Komhyr et al., 1982). One such program invo l ves routine comparison of GMCC and SIO CO 2 flask sample data for BRW, KUM , 

~lLO, and S~ 0. The GMCC and SIO samp l es are co llec ted at these stations qua sisimultaneously , and data. are e~c hang d wi thout prior knowledge of the cooperating laboratory's results. For 54 se ts of data compared during June through 

De cemb er 1981, the mean GMCC-SIO CO 2 concentration difference was 0.06 ppm. 

In a similar effort performed according to a WHO recommendation (~lO, 1981), a 

program was initiated late in 1981 with SIO whereby 12 G~lCC fla s ks are sent to 

SIO for exposure four times each year. When sampling conditions are sa tisfac -

to ry , SIO collects CO 2 air samples in the GMC C flasks using GMCC te chnique s 

and, quasi-simultaneously, in SIO sampling flasks. GMCC flasks are returned 

27 
E 

~ 

~ 

~ 

~ 

~ "' 

.!l 

16 

14 

12 

OJ 0 

0 

• 0 

6 

• I 

2 

~=-~_~~_~60~_~'5~_~30~_~I5~~O--~=-~~~~.L5~60L-~~L-~90 

Lotitude 

Figure 6.--Meridiona l distribution of 

the amplitude of the sea sonal CO 2 concentration . The solid line is a 

fourth- order polynominal fit to the 

data (*), and the symbol 0 represents 

stations either not at sea level or at 

very disparate longitudes , which were 

not included in the fit. Weathership 

p data are plotted for comp arison. 

to Boulder for analysis, and S10 flasks are analyzed at S10. Exchange of 

sample analysis data between the two laboratories is through Wl'1O in Geneva. 

Finally in yet another endeavor to assess CO 2 data quality, GMCC flasks 

and continuous apalyzer data at BRW, MLO, and SMO were intercompared beginning 

in June 1981 when use of CO 2 -in-air calibration gases was extended to all 

three stations. On the average , biases of only 0.1-0.2 ppm were observed 

(Komhyr et al., 1982). Such agreement in results is gratifying considering 

that the methodologies of flask and continuously operating analyzer CO 2 measurements differ significantly and that widely different environmental conditions are represented, namely, the humid, sea l eve l atmosphere of SMO and the 

dry, rarefied air of MLO. 

160 

Day or 

Figure 7.--Three-dimensional representation of the edited 1981 global 

atmospheric CO 2 distribution from the 20 flask sampling stations, a synthesis of the 1981 data presented for each station in fig. S. 

28 
3.1.3 Miscellaneous 

Thomas B. Harris retired in August 1981 after 34 years of government 

service, of which the last 10 years were in the GMCC program. Harris participated in the si te selection of the GMCC observatories a nd was responsible 

for the operation of instrumentation in the CO 2 monitoring program . 

3 . 2 Total Ozone 

3.2.1 Routine Observing Program 

Routine total ozone observa tions with Dobson ozone spectrophotometers 

were continued in 1981 at the four GMCC stations, one foreign cooperative station, three domestic cooperative stations, three NWS stations, and GNCC headquarters, Boulder. Table 7 lists the 12 stations, instrument numbers, the 

agencies responsible for taking observations, and observing time periods for 

which data are available. 

During June, July, and August 1981, World Standard Dobson Ozo ne Spectrophotometer no. 83 was operated at MLO to check its calibration. No significant change was found. In September 1981 a trip was made to Nashvil le, Tenn ., 

to erect a new 10-ft 6-in Ash Dome spectrophotometer s helter and to train station observers in the operation of the Dobson instrument. On 5 October 1981 

observa tions of total ozone were reinstated at Tallahassee , Fla. They had 

been temporarily terminated at that station in May 1979 . 

3.2.2 Calibration Check of Dobson Spectrophotometers in the Global Network 

In 1981 G~!CC began a proje ct in cooperation with the WHO Global Ozone 

Research and Monitoring Project. The global Dobson ozone spectrophotometer 

station network was divided into seven regions to check the calibration levels 

of those instruments in use throughout the world. A standard l amp power supply and two calibra ted sta ndard lamps will be shipped to each region. Upon 

Table 7.--U.S. Dobson ozone spectrophotometer station network for 1981 

Station Period of record Instrument no. Agency 

Bismarck, N.D. 1 Jan 1963-present 33 NOAA 

Caribou, Maine 1 Jan 1963-present 34 NOAA 

Tutuila Is., Samoa 19 Dec 1975-present 42 NOAA 

Tallahassee, Fla. 2 Jun 1973-present 58 NOAA-Fla. 

State Univ. 

Mauna Loa, Hawaii 2 Jan 1964-present 63 NOAA 

Wallops Is. , Va . 1 Jul 1967-present 38 NOAA-NASA 

Barrow, Alaska 2 Aug 1973-present 76 NOAA 

Nashville, Tenn. 1 Jan 1963 -present 79 NOAA 

Boulder, Colo. 1 Sep 1966-present 82 NOAA 

White Sands, N. ~!. 5 Jan 1972-present 86 NOAA-Dept. 

of Army 

Huancayo, Peru 14 Feb 1964-present 87 NOAA-Huancayo 

Obs. 

Amundsen-Scott, Ant. 5 Dec 1963-present 80 NOAA 

29 
recelvlng the lamp unit, observers at each station will perform standard 

tests on the Dobson instrument and determine the N-va lue for each lamp. 

suIts of the tests will be sent to Boulder for ana l ysi s to determine the 

bration status of each instrument and to identify instruments requiring 

recalibration. 

lamp 

Recali3.2.3 tlodernization and Calibration of Dob son Spectrophotometers 

During 1981 GNCC personnel continued to participate in the Wl10 Global 

Ozone Research and Monitoring Project to upgrade the quality of Dobson spectrophotometers throughout the world. In June, Dobson instrument no. 64 from 

Potsdam, G.D .R, arrived in Boulder for modification and recalibration. New 

electronic circuitry and an electromecha ni ca l phase-sensitive rectifier were 

installed. After installation of an "air-space" optical wedge and alignment 

of optical components, instrument no. 64 was calibrated by direct comparison 

with the World Standard Dobson Instrument no . 83 and returned to Potsdam. 

In August, U.K. instrument no. 41 arrived in Boulder for modification and 

recalibration. A provisional calibration showed it to be +2.7% out of calibration. The U.K. technician who accompanied the instrument to Boulder installed new solid state electronics and a new optical wedge. After alignment 

of the optical components, the instrument was calibra ted by direct comparison 

with instrument no. 83 and returned to the United Kingdom. 

Nashville, Tenn., instrument no. 79 and Tallahassee, Fla., instrument 

no. 58 were recalled to Boulder for minor modifications and recalibration. 

Results of intercomparisons made with these two instruments and instrument 

no. 83 indicated that the Nashville calibration was +3.33% in error, and the 

Tallahassee calibration was -2.62% in error. 

3.2 . 4 Total Ozone tlonthly Neans 

Daily 1981 total ozone values (applicable to local apparent noon) for all 

stations in the U.S. network have been submitted to and are available from the 

World Ozone Data Center, Atmospheric Environment Service, 4905 Dufferin 

Street, Downsview, Ontario N3H5T4. Table 8 lists monthly mean 1981 total 

ozone amounts for the NOAA observatories and cqopera tive stations. 

Table 8 .--Provisional 1981 monthly mean total ozone amounts (mi lli-atm-cm) 

Station Jan Feb tla r Apr tlay Jun Jul Aug Sep Oct Nov Dec 

Bismarck, N.D. 350 386 378 383 371 347 314 311 292 303 310 358 

Caribou, ~laine 390 381 427 435 401 386 364 333 32 1 320 335 339 

Wallops Is., Va. 340 350 374 351 370 324 328 321 307 296 305 323 

Tutuila Is., Samoa 256 254 260 256 263 265 264 258 268 268 272 266 

Tallahassee, Fla. 279 28 1 287 

Mauna Loa, Hawaii 241 251 268 288 28 1 278 269 269 268 264 254 254 

Ba rrow, Ala s ka 432 387 368 350 320 327 

Nashville, Tenn. 334 357 362 347 374 346 347 287 291 320 

Boulder, Colo. 322 346 357 343 369 322 313 307 298 293 287 306 

White Sands, N.N. 300 315 331 322 340 320 317 315 281 285 270 272 

Huancayo, Peru 265 261 263 267 265 271 268 275 278 281 279 273 

30 
3.3 Ozone Verti~al Distribution 

3.3. 1 Umkehr Observations 

Umkehr observations yielding ozone profiles were continued at Boulder 

during 1981 with Dobson spectrophotometer no. 81. In December, regular measurements were begun using the automated Dobson instrument no . 61. The manual 

observations were continued during December to obtain comparison data. 

Instrument no. 61 has been automated by mating an HP-85 computer to it 

for control and data processing. By con trolling stepping motors to perform 

functions normally performed manually by an observer, the HP-85 selects the 

wavelengths at whic h observations are made and measures the difference in 

light intensity between strongly and weakly absorbing ozone lines. The shutter of the Ash Dome shelter has also been automated. (Precipitation detectors 

are used to keep the shelter closed during adverse observing conditions.) 

Umkehr observations are, therefore, completely automatic. Total ozone measurements have been semiautomated. After setting a sun director on the instrument 's light inlet window and orientating t he instrument correctly with respect to the sun, the operator merely activates a switch to initiate the total 

ozone measurement. About 2 minutes l ater the computer outputs the total ozone 

amount in Dobson units. 

At the request of EPA and CMA , a proposal was written for automation of 

six additional Dobson spectrophotometers and establishment of a global auto-

,"ated Dobson instrument Umkehr observation station network by 30 April 1984. 

Data from the network are expected to provide information on possible longterm ozone destruction (e.g., by halocarbons) near 40 km. Data obtained will 

also be useful for comparison with satellite-derived atmospheric ozone vertical distributions. 

3.3.2 Umkehr Data Analysis 

Monthly mean ozone partial pressures derived from Umkehr observations for 

nine levels in the atmosphere are shown in fig . 8 for the 4 years of observations made in Boulder. In the layers below 4 mb a discernible annual variation exists. Below the 30-mb layer this cycle is associated with the wintertime poleward transport of ozone and s hows a springtime maximum. Above 30 mb 

but below 4 mb the seasonal maximum occurs during the summer corresponding to 

a maximum in t he photochemical production of ozone. In the two layers above 

4 mb (note the mu ch-e xpanded scale for these two layers in fig. 8) a semiannual cycle appears to predominate . It is in these top two layers that the 

largest percentage change due to the impact of halocarbons is expected. These 

data from Boulder show no .readily discernible long-term trend for the 4 years 

of data shown. 

3.3 . 3 ECC Ozone so nde Observations 

A program was conducted during 1981 to extend balloon-borne ECC ozonesonde observations to the photochemically important stratospheric region of 

40 km . The initial effort was concentrated in developing a reliable but inexpensive and easy-to-handle balloon vehicle system to carry the ozonesondes to 

desired heights. Some success was obtained with neoprene rubber balloons 

31 
" " ~ 

0 

c 

• Z 

.< 

• ; 

" " 

~ Q. 

~ 

~ Q. 

• C 

0 

N 

0 

,0 

8 

6 A ... 

::~ ~ ... 

:~ 0---0-0'" ---

,oo~ 0....,,/" •• 

75 

'25~ "y.-.-

100 

125~ ,00 

:~ ~ .. -

:~ j\" 25 

2:~ ~ .. NO O~ 0 8S, I , 3 0 5 :s :s 5 '" 8 5 , , , . , 6 6 6 8 7 " 9 4 10 10 5 8 6 :5 8 6 I 7 1 5 5 6 7 5 

350 A .. • 

300 • 

250 0 J , M J F M A M J J A S O N 0 J f M A M J J 

I 1978 1979 1980 I 1981 

Figure 8 . --Monthly mean ozone amounts at various levels in the atmo sphere obtained from Umkehr observations in Boulder, Colo. 

whose performance characteristics were found, however, to vary from batch to 

batch. Overall success rate in achi eving 40-km heights was unde r 50%. In 

late 1981 a new plastic balloon ma teria l became commercially available that 

enabled balloons to be fabricated from materia l only about 0.006 ~n thick. 

Whereas previously available plastic sheet balloons capable of carrying a 2-kg 

ozone sonde payload to 40 km weighed nearly 25 kg and required la rge amounts of 

helium, balloons made from the new material weigh only 7.5 kg and r equire only 

two tanks of helium for inflation (about 15 SC~1). Success rate in using the 

new balloons has been nearly 100%. 

Ozone vertical distributions to 40 km measured in Boulder during 1981 are 

shown in fig. 9. The soundings were made with Science Pump type 3A ECC ozonesondes. As a result of errors in pressure measurements above about 5 mb and 

variations in pumping efficiency from instrument to instrument, considerable 

32 
2 

5 -35 

10 

:0 20 

E. 

i" 

~ 50 ~ 

~ 

i" 

Cl. 100 

200 

500 

1000 .1 .2 

0 100 150 0 50 100 150 0 50 100 150 0 50 100 150 

Partial Pressure of Ozone ",mb) 

2 

5 -35 -35 

10 

:0 20 

E. 

i" 

~ 50 ~ 

~ 

i" 

Cl. 100 

200 

500 

1000 .2 .1 .2 

0 50 100 150 0 100 150 0 50 100 150 0 50 100 150 

Partial Pressure of Ozone ~mb) 

Figure 9 . --High-altitude ECC ozone soundings made in Boulder, Colo. , 

during 1981. 

uncertainty exists in the reliability of the sonde dat a a t a ltitudes above 

10 mb. Recently, a new pump for ECC ozone sondes has been developed (Komhyr, 

1981) that is expected to perform more reliably at high altitudes. Pump components are fabricated from TFE Teflon reinforced with 15% glass fibers . The 

piston and cylinders are of conventional design with circular cross sections, 

but the cylinder is fitted with externally located rubber rings that compress 

thin, flexible portions of the cylinder wall aga inst the piston to form an 

effective piston- cylinder seal. Type 4A ECC ozone sondes are equipped with the 

new pumps. The new pumps are currently being tested t o determine pumping efficiency at pressures of 100-2 mb. 

33 
3.4 Surface Ozone 

Dasibi ozone photometers were operated at the four GMCC stations throughout the year . All of the station instruments have been intercompared with the 

GMCC standard photometer maintained in Boulder. In addition, three secondary 

standard instruments were established . One of the standards is to be maintained at SPO. The second will be used within the GMCC surface ozone network 

as a traveling standard for use in periodically calibrating station instruments at ~ILO, S~10, and BRW . When not in use as a traveling standard, this 

instrument will be located at MLO for more frequent calibrations of that station's instrument. The third standard is used in the GMCC ozone sonde program, 

and to check the stability of the Boulder standard photometer. Figure 10 diagrams the use of the Dasibi ozone photometers within the GMCC network. 

NBS STANDARO 

PHOTOMETER 

GMCC 

STANDARD 

OASIBI 2172 

SURFACE 

/ 

OZONE 

~ OZONE SONDE 

SECONDARY SECONDARY 

STANDARD STANOARD 

OASIBI 331 4 OA51611603 

I I M AUNA LOA BARROW SAMOA 

OA5 1911328 OA51611321 DASIBI 1326 

I SOUTH POLE 

OA5161 1316 

CALIBRATION 

DASIBI 1323 

Figure 10.--Locations and use s of 

Dasibi ozone photometers in the GMCC 

surface ozone network. 

Data for 1980 have not be en pro ce ssed but will be available in the future. The GMCC Summary Report for 1978 (Mendonca, 1979) and Oltmans (19 81) 

describe shorter time s cal e variations in surf a ce ozone at the GMCC observatories. With the addition of several more years of data it should be possible 

to investigate year-ta-year variations in surfa c e ozone . 

3.5 Stratospheri c Water Vapor 

3.5.1 Operations 

Balloon flights to measure stratospheric water vapor were made monthly 

during the year. Twelve successful flights were made in Boulder, and one 

flight was made in Palestine, Tex., as part of an international intercomparison of water vapor instruments . The measurements were made with frost-point 

hygrometers described in the GMCC Summary Report for 19 78 (Mendonca, 1979). 

34 
3.5.2 Data Analysis 

Figure II portrays the 13 water vapor soundings made during 1981. The 

mass ffilxlng ratio of water vapor is plotted as a function of pressure for the 

region above the tropopause. The strong seasonal variation in the region 

around 100 mb and the relatively constant mixing ratio with alti t ude above 

60 mb are noteworthy. During winter a minimum develops in the 14- to 16-km 

layer. The minimum weakens during the ensuing months and moves upward to the 

19-km level by fall, where it disappears by year's end. A surprising feature 

is the appearance in October of a well-defined minimum, a feature that is seldom seen earlier than January in the Washington, D.C., soundings. This may be 

indicative of slightly different lower stratospheric airflow patterns over the 

t wo sites. 

4 

\ I 

13 Jan 3 Feb 11 Mar 23 Apr 7 May 30Jun 17 Jut 17 Aug 22Sep 

81 Palestine 

Texas 

, 

, 

, 

I 20 

: 

, 

, 

, 

, 

, 

, D 

S 40 -

~ 0 

~ 

~ 

, 

, 

I 

, 

, 

, 

, ~ 60 "-

, 

I 

" , 

50 :, -

, 

, 100 , 

: , 

, 

, 

, 150 , 

, 

~---

200

0 2 2 2 2 2 2 

Mass Mixing Ratio (ppmm) 

Figure 11.--Water vapor mass mixing ratio profiles 

Boulder, Colo., and 1 sounding in Palestine, Tex. 

margin give volume mixing ratio in ppmv. 

190ct 4 Nov 17 Dec 30 

X·43 , 81 

X·35 28 

26 

24 

E 22 ~ 

.c 

'" 20 '0; 

I 

18 

16 

14 

12 

2 2 2 

for 12 soundings in 

Numbers a l ong t he top 

In October two water vapor sondes were launched within 3 hours of each 

other. Good quantitative agreement was achieved, with the differences l ying 

within known measurement uncertainties. 

The 12 soundings made in Boulder provide an opportunity to compare these 

measurements with soundiflg s made from 1964-1980 at Washi ngton, D.C . , by NRL . 

At a level of about 60 mb t he annual cycle in water vapor is relatively sma ll , 

and as fig. 12 shows, the data from Boulder are somewhat less variable than 

earlier data from Washington, D.C. This reduced variability, which is typical 

of all altitudes, is probably a result of the i mproved instrwnentation now 

being used . 

An analysis of the data shown in fig. 12 reveals two importa nt longer 

term cycles. If a 12-mo running mean is appl ied to these data (fig. 13), a 

35 
'. 

'. 

" 

> 

o Washington, DC 

• Boulder, CO 

~~~,--~,,~-7..---7.---,~,--~,~,--~--~--~~ 

Dale 

Figure 12.--Time series of water 

vapor mass mixing ratio at 60 mb for 

Washington, D.C. (open circl es), and 

Boulder, Colo. (filled circl es). 

" . " .. ::; 

~ 

D " 

-1 ~!;---;;--;~-7,---7.---:'" --~.;-, ---;,----:",---;---!. 

Date 

Figure 13.--The 12-mo running mean 

and parabolic trend of monthly water 

vapor mass mixing ratio at Washingt on, D.C., and Boulder, Colo. The 

long-term mean has been subtracted 

from the data. 

quasi-biennial cyc l e is strongly suggested, especia lly after about 1971. 

Because a number of months of data are missing, especially in the late 1970' s 

and in 1980, this finding mu st be considered preliminary. Comparison of this 

variation with the zonal winds at 50 mb at Po nape, located at about 7°N 

(fig. 14), shows that, since 1971 , the minima in midlatitude water vapor concentration follow the minima in the Ponape zonal winds by about 10-12 months. 

This is consist ent with the relationship between stra tospheric ozone behavior 

at the quasi - biennial period (Oltmans and London, 1982). 

Also shown in fig. 13 is a nonlinear trend fit to the data, which shows 

generally increasing values from 1964 to 1972 and decreasing values thereafter. By 1981 the Boulder values were nearly as low as those at the beginning of the observational series at Washington, D.C . 

• 

Date 

36 

Figure 14.--The 12-mo running mean 

of the 50-mb zonal wind at Po nape 

(l°N) . 
3 .6 Ha l ocarbons and Nitrous Oxide 

3.6.1 Opera tions 

Ro utine coll ection of a ir i n stainl ess steel flask pairs continued during 

1981 at the four GNCC stations and a t NWR. Samples were collected weekly at 

a ll stations excep t SPO where biweekly sampling prevailed. Sample quality was 

gene rally high, excep t at SPO where long storage time and extreme t emp e ratures 

degra ded t he samples . Analysis of the air samples for CFC-11 (CC1 3F), CFC-12 

(CC1 2F2 ), and nitrous oxide (N 2 0) conti nued at the Boulde r chromatographic 

l aboratory with f ew instrument probl ems and no procedural change s. 

A used Perkin Elme r 3920 gas chromatograph, obtained in 1980, was totally 

reconditioned in 1981 . Detectors were sent to Nuclear Sources and Services, 

Inc., for clea ning and testing. The electrometer circuit board was exchanged 

for a new one, all new carrier gas lines and controls were installed, temperature circuits we re calibrated, oven insulation was improved, and a sampling 

valve was modified to provide on-column sample injection. After reassembly of 

the chromatograph, tests indi ca t ed that the detector response was high but 

sensitive to e nvironmental temperature changes . 

The chromatographi c l aboratory was reconfigured in Decemb er by installing 

all ancillary equipment in a rack be tween the two gas c.hromatographs. This 

has greatly facilitated samp l e ana lyses. Additions to the l abora t ory in 1981 

were a spare p ress ure manometer system and flow controller system. 

3 . 6.2 Calibration 

The GNCC CFC- ll, CFC- 12, and N20 secondary standard ca libration gas t ank 

(no. 3072) was sent t o R. Rasmussen of OGC in April for its r outine stability 

check. Res ults s howed a dec r ease in CFC-11 and a continuing increase in 

CFC- 12 . 

A question has been raised concerning the stability of the GNCC CFC-12 

calibration secondary standard since no drift of this standard has bee n detected during ca libration intercomparisons performed in Boulder relative to 

two other CFC- 12 ca libration gases. Tank no. 3072 gas has been intercompared 

qu arterl y with t ank no. 3079 gas for 3 years and with tank no. 3088 gas for 

4 years . This problem points to the neccessity of maintaining an independent 

calib ra tion faci lity in Boulder f or the halocarbon and N20 monitoring 

programs . 

An abso lute calibration system for trace gases such as CFC-ll, CFC-12, 

and N2 0 was devised by W. Komhyr in 1979 (mICC Summary Report for 1980, 

DeLuisi, 1981). As applied (e.g., to N20), the method involves preparation by 

gravimetric means of an N2 0/C0 2 ga s mixture of accurately known ma ss ratio, 

and subsequent dilution of this mixture with N20- and CO 2 -free air to approximately ambi ent air conc entra t ions of the se trace gases . From a determination 

of the abso lute CO 2 conc entration in this dilution mixture using accurately 

ca lib rated CO 2 gas standards and an NDIR analyzer, the N2 0 concentration in 

the dilution mixture is readily inferred. CFC- 11 and CFC- 12 trace gases are 

ca libra t ed by a similar method. 

37 
Preliminary work in implementing the calibration technology described 

above has alrea dy bee n accomplished. Calibration data obtained for N2 0 indicate concentration values 10% lower than those obtained at OGC, but i n agreement with those obta ined by other r esearchers . These differences wil l be resolved in the nea r futur e . 

3.6.3 Data Analyses 

Selected 1981 data for CFC-ll, CFC- 12, and N20 have been added to 4 years 

of previous data and are plotted in figs . 15, 16, and 17, respectively. Mean 

concentra tions for 1981 and results of least-squares quadrati c regression 

analyses of the 5-yr data sets for CFC- l1 and CFC-12 are summari zed in 

table 9 . CFC- l1 mean mixing ratios for 1981 are in the range of 188-205 pptv, 

with the highest concentration found at BRW. Regression analyses predict mixing rati os in the range of 135-154 pptv on 1 January 19 77 and growth rates in 

the range of 11-14 pptv yr- 1 . CFC-ll data f or MLO s how a slight but statistically significant decrease in growth rate. CFC-12 mean mixing ratios for 

1981 are in t he range of 321-345 pptv, with the highe st concentration again 

found at BRW. Regression ana l yses predi ct mixing ratios in the range of 239-

276 pptv on 1 January 197 7 and growth rates in the range of 12-18 pptv yr- 1 . 

CFC-12 data f or BRW and SPO s how statistically significant increas es in growth 

rates . The CFC- 12 data incorporate corrections for calibration gas drift as 

indicated by ca librations performed at OGC . It is likely that results for 

CFC-12 will cha nge significantl y foll owing resolution of the gas ca libration 

problem referred t o in sec . 3.6.2. 

Table 9. - -tlean mixing ratios for 1981 and results of least-squares 

quadrati c r egression analyses of GMCC CFC-ll and CFC-12 data 

for 1977-1981;' 

S lati o n No . of Nean mixing Ni x i ng ra tio Growth ra te Grow th rate change 

obs. rat io for 1981 on 1 Jan 1977, ( pptv y r-' ) (pptv yr-z)'t 

(pp t v) (pptv) 

CFC-ll 

BRW 209 204 . 7 153.7 ± 0.45 11.33 ± 0 . 16 

NWR 216 199.0 150 . 5 ± 0 . 47 10.78 ± 0.16 

llLO 210 196.7 141.2 ± 0.80 14.36 ± 0 . 70 - 0. 45 ± 0 .1 3 

5110 221 188. 3 135.4 ± 0.40 11 . 76 ± 0.14 

SPO 75 188.0 138 . 4 ± 1. 89 11 .02 ± 0 . 61 

CFC -1 2 

BRW 190 345 . 4 274.4 ± 2.11 12. 63 ± I. 64 0 . 70 ± 0 .28 

NWR 143 337 .5 275 .5 ± 1. 42 13.78 ± 0.40 

NLO 190 339. 7 267.4 ± 1.22 16.08 ± 0.41 

5110 216 322 . 3 243 . 4 ± 0 . 83 17. 53 ± 0 . 29 

SPO 70 321. 3 239 . 4 ± 3.30 12.09 ± 2.53 1. 36 ± 0.44 

*Coeffi c i e nts a re f o llowed by their standard deviations. 

t98% confi dence interva l . 

38 
0 

" ~ 0 

:; ~ 

0 

· 0 

• 0 

" ~ 0 

., ~ 0 0 

" 0 " 

;; 0 ," \\\R 

g 0 

~ 

~ 0 

~~ 

~ 0 

~ 

~ ~ ~ 

" 0 

0: ;; , 

0: ~ \ 11.0 

'" • 

t: 

!l 

0 

., 

0 

" g 

'i r; 

t: 0 

~ 

~ 0 

0 

0 

:; 

0 

· 

~ 

:-:\10 ~ 

~ 

~ 

~\ O 

.... ~ .... ___ -. ., .. v~·.--,...-.."'''~~ '..' . ..,;"-"". 

" .. ' 

~ ~ 

! I'" .~:" " , . :- ",/.;. ,1 ! 1," ;"-' '.',-,"~ .... , . 1 :., ........ .' 't_ 

77 7. 7') flO '" 77 7. 7') IlO H' 

Figure lS.--GMCC's CFC-II data record . Figure 16.--GMCC's CFC -1 2 data record . 

0 

., 

0 Bill' 

~ 

0 

0 

" 

~ 

§ 

" \\\R 

0 

• 

~ 

~ 

?, 

" 0 

;;- 0 

0: 0 

B • 0 

/ ?, 

\ll.0 . . ": ·I·:'::.-:·--:-:-:: .. ·.~-~··-: ... · .. ~' .-:·:'·~7·.;· ....... ·.~·:·· ... \.' .. ·~ .. -· .. ·"'· ... :·.:..··\ 

~ 

§ 

" ~\lO 

0 

• ':" ...... : •.. , .••• ~ ..... ~_.'.:J~.: ..... ;:-;:: .•• ::, ... '!':*,,:~ '-.~' ~.:~:.:''''01:~':>- ..... 

~ 

~ :-' I _' ,", ..~.y.' ..~ 1 .. '" 

"I 

Figure 17. - -GMCC' s N 20 da t a record . 

39 
Table 10.--Mean mixing ratios for 1981 and results of least-squares 

quadratic regression ana l yses of GMCC N20 data 

for 1977-1981'" 

Station No. of Mean mixing Mixing ratio Growth rate Growth rate change 

obs . ratio for 1981 on 1 Jan 1977 (pptv yr -1) (pptv yr- 2 )t 

(pptv) (pptv) 

BRW 199 302.5 300.4 ± 0.23 0.47 ± 0.08 

NWR 187 303.2 298.5 ± 0.47 1. 76 ± 0.37 -0.16 ± 0.06 

mo 199 302.0 298.9 ± 0.28 0.70 ± 0 .09 

SMO 197 304. 1 297.4 ± 0.58 3.67 ± 0.45 -0.48 ± 0.08 

SPO 94 301. 1 297.6 ± 0.39 0.78 ± 0.11 

';'i'Coefficients are followed by their standard deviations. 

t98% confidence interval. 

Mean concentrations and summary results for similar regression analyses 

of the N2 0 data are presented in table 10. N2 0 mean mixing ratios for 1981 

are in the range of 301-304 pptv, indicating that the gas is well mixed globally. Regression analyses predict mixing ratios in the range of 297-300 pptv 

on 1 Januaty 1977. Growth rates are in the range of 0.5-1.8 pptv yr- 1 , except 

for SMO, which shows the much larger growth rate of 3.67 pptv yr- ' t hat is not 

yet explained. N20 data for NWR and SMO show small but statistically significant decreases in growth rates. 

3 . 7 Stratospheric Aerosols--Lidar 

3.7.1 Operations 

Twenty-four successful lidar observations of the stratosphere were made 

during the second half of 1980, and 22 successful observa tions were made 

through 1981. The operational plan for lidar observations calls for an average rate of one observation every 2 weeks during unperturbed stratospheric 

conditions and an increase in the frequency of meas urements where significant 

enhancements in stratospheri c dust are detected. 

3.7.2 Data Analysis 

Lidar data for 1980 and 1981 have been processed and will be published, 

along with a summary, in a NOAA Technical Memorandum. A brief summary of the 

1980-1981 observations is given here in terms of stratospheric dust optical 

depth integrated between approximately 13-15 to 28-30 km, which is the upper 

limit of the sounding. 

Figure 18 shows a plot of stratospheric dust optical depth (A = 694.3 run) 

vs. time using the present data set . No range of uncertainty is given with 

these data; however, a comparison between these values and va lues of stratospheric dust optical depth for 1980 deduced from the MLO apparent transmission 

40 
75.0;-~~~~~~~~~~~;-,,~~~--, 

70.0 

65.0 

60.0 o 

-;:; 55.0 

i:: 

" .g 40.0 n 

035.0 

30.0 

25.0 1980 1981 

20.0 l--'~~~~~'---'~---'--!::-~~:':-c':-'-L---'---' 

~~J&g~8~~~~~~~J~2~8~ Date 

Figure IB.--Stratospheric dust optica l depth (A = 694.3 nm) at HLO as 

deduced from lidar observations duri ng 19BO and 19B1 . 

measurements s howed that thes e va lues do not differ significantly. 

tion of the uncertainty in lidar optica l depth estimation by using 

cal trans mission meas urements is planned. 

Determinaother optiThe data plotted in fig. I B reveal some interesting features. The first 

is tha t the variation i n optical depth from minimum to ma x imum i s about a factor of 3; the second is that the average optical depth of 0.005 (approximate) 

is what could be expected for an unperturbed stratosphere ; a nd the t hi rd is 

that an i ncreasing trend is seen during June to November in 19BO whereas the 

opposite is seen in the 19B1 data. If an a nnual cycle in stra t ospheric dust 

optical depth does exist (as in the case of tropospheric dust opti ca l depth), 

it may be easi l y disguised by volcanic eruptions that are expected to occu r at 

random. As the size of the lidar data record is lengthened it may eventua lly 

be possible to isolate an a nnual cyc l e. 

3.B Surface Aeroso l s 

The G~ CC surface aeroso l monitoring program during 19B1 included t he continuous measurement of CN concentration a nd i ntegrated light sca ttering at 

BRW, HLO, S~10, and SPO. All data were recorded on magnetic tape and ba ckup 

chart recorders. The da t a from the ma gnetic tape are available as both minute 

a nd hourly means . The Leeds and Northrup Speedomax 250 chart recorders print 

about t hree points per minute for each channel and provide information for 

qua l ity contro l in addition to fill- data t o cover downtime for the dat a acquisition system. 

CN concentrations were measured using G.E. automatic CNC's (catalog 

no. 112L42B) with modifications sugge sted by N. Ahlquist of the Univers ity of 

Wa s hington. The modifications have res ulted in improved sensitivity and reliability for these i nstrumen ts and have been discussed in the GHCC Summary 

Report for 1976 (Ha nson, 1977) . Poll a k CNC's (model P, BGI, Inc., Waltham, 

Hass.) are l oca ted at a l l sites as secondary sta ndards to provide calibration 

for the automatic CNC's . A calibration check and a background comp ensation 

adjustment for t he automatic CNC are pe rformed daily. The calibration procedure is explained in detail by Bodhaine and lurphy (19BO). 

Light sca ttering was measured at the GHCC stations using specia lly construc t ed four-wavele ngth integrating nephelometers manufactured by HRI, Inc . , 

41 
Table ll. --Serial numbers of aerosol instrwnents at G~lCC stations 

Instrument 

Pollak CNC 

Nephelometer 

BRW 

16 

105 

NLO 

13 

103 

Stl0 

20 

106 

spa 

15 

107 

Altadena, Calif. These instruments measure a ,the scattering portion of 

sp 

extinction due to particles, simultaneously at 450-, 550-, 700-, and 850-nm 

wavelengths. Operation of the nephelometers is discussed in more detail in 

Hanson (1977) and Bodhaine (1979). Calibration of the nephelometers is performed at 2-mo intervals by filling them with CO 2 gas and adjusting the instrument outputs to agree with the known scattering coefficients of CO 2 , 

Checks of the i nstruments' internal voltages are mad e daily. Weekly relative 

calibrations are performed using the internal calibration objects built into 

the instruments. 

Table 11 gives the seria l numbers of the Pollak CNC's and nephelometers 

located at the GMCC stations. 

3 . 8. 1 Ba r row 

The BRW Pollak CNC operated properly throughout 1981 without problems. 

Daily observations provided routine calibration checks for the G.E. automatic 

eNe. These observations have been keypunched and are available as a separate 

file on the Boulder computer. The G.E. CNC produced acceptable data for 89% 

of the hours in the year. Other than downtime for routine calibration and 

maintenance, the major periods of downtime were DaY 1-1 3 , 111-113, and 

305-314. 

The nephelometer produced acceptable data for 97% of the year, with the 

only signifi ca nt downtime occurring during DaY 7-13, 57, 106, 132 , 237, and 

some minor intermittent problems occasionally during 290-309. 

3.8 . 2 la una Loa 

The MLO aerosol mea s urement program was started in September 1967 by 

B. Mendonca using Gardner counter SN826. Subsequently, A. Hogan of ASRC/SUNYA 

installed Pollak CNC SN13 (to be used to calibrate the G.E. automatic CNC), 

and routine Pollak CNC observations began in June 1974. All data taken with 

the Gardner and Pollak CNC's have been keypunched and are available on the 

Boulder computer. 

The tlLO Pollak CNC operated properly throughout 1981 without problems. 

Daily observations provided routine calibration checks for the G. E. automatic 

CNC. The G.E . CNC produced acceptable data for 87% of the year. The only significant downtime occurred during DaY 56, 59 -61, 64-67, 80-8 1, 84-85, 165-166, 

171- 175, 344, 347-348, and 358-365. Most of these data could be recovered 

from the backup chart recorder. 

The nephelometer produced acceptable data for only 37% of the year. 

Periods of downtime were DaY 45-61, 80-81, 109-110, and 143-365. In June the 

42 
instrument was shipped to Boulder and then to the University of Washington for 

repair, and was down for the remainder of the year. 

3.8.3 Samoa 

The SMa Pollak CNC operated properly throughout 1981 without problems. 

Daily observations provided routine calibration checks for the G.E. CNC. The 

G.E. CNC produced acceptable data for 88% of the year. The only significant 

period of downtime was DaY 80-114 when the instrument was shipped to Boulder 

for repair. 

The SMO nephelometer produced acceptable data for 77% of the year. The 

instrument underwent modifications at the University of Washington to allow 

operation of a Hamamatsu photon-counting photomultiplier at room temperature 

rather than the RCA type C31034, which requires a thermoelectric cooler. The 

instrument experienced no significant downtime after it was installed on 

DaY 74. 

3.8.4 South Po l e 

The spa aerosol measurement program was started by A. Hogan in 1974 with 

the installation of Pollak CNC SNI5, funded by NSF. 

The spa Pollak CNC operated properly throughout 1981 without problems 

except for the period DaY 59-64 when the humidification element in the instrument was dry. The G.E. CNC produced acceptable data for 73% of the year . 

Downtime occurred during DaY 283-365; on opening flight the instrument was 

shipped to Boulder for repair. The problem was unusual a nd was finally traced 

to a dirty meter switch that apparently was causing unpredictable feedback 

paths throughout the circuitry. 

The nephelometer arrived at spa in January 1981 with several broken components and an inoperable high-voltage power supply. The instrument was 

online DaY 30 and produced acceptable data for 64% of the year. Other than 

January, most of the downtime was caused by slow recovery of the instrument 

after a relative calibration. 

3 .8 .5 Data Analysis 

Data analysis ha s proceeded as described in the previous annual reports . 

All observer notes and chart recorder data are examined upon receipt in Boulder to assure proper instrument performance. Aerosol data are stripped from 

the monthly tapes made available by the A&D~I group, and files of hourly means 

and la-min graphics are produced. Missing data are then filled in, and necessary editing and calibration are applied. All aerosol data are available from 

GMCC in printout, microfiche, magnetic tape, or graphic form. 

3 . 8.6 Discussion of Selected Data 

Light scattering a and CN data for the four stations are presented in 

sp 

fig. 19. All available data were used to calculate monthly geometric means, 

43 
-4 

-5 Barrow 

- 6 \ 

-7 

-5 

-6 

~ 6 C="-> ... <"'> fl./\.. "6 ~ _ ~ --=J3 ""'" - ~V~..· VVV"'" 2 

- 4 [ Samoa 

-5 IV ~ ... A.. ... ~ ... -. 

I\. 0'6 

- vv-r 9 ~ 06 > -r 

2 

~ ~ 3 

- 6 t - 7 South Pole 

-8 

2 

1 

74 75 76 77 78 79 80 81 

Year 

'" I 

E 

<.> 

z 

o 

Ol 

.2 

Figure 19 .--Monthly geometric means of all light-scattering IT and eN 

sp 

data acquired at BRW, MLO, S~lO, and SPO . Only 0000-0800 LST data for 

MLO were used . Linear least-squares trend lines are shown for all data 

sets except SPO light scattering. The dashed line for BRW light scatt ering is the trend with 1976 data omitted . Details of t he trend ana l ysis 

are given in table 12. 

44 
Table 12.--Least-squares trend analysis of the common logarithms 

of the data given in fig. 19" 

Slope Intercept S.E . t Trend yr- 1 

BRW 

a (solid) -0.00388 

sp 

-5.037 0.4005 -10.0% 

a (dash) -0.00927 -4.637 0.3522 -23 .0% 

sp 

N 0.0000253 2.253 0.2824 0.7% 

MLO 

a 0.00384 -6.340 0.3387 11. 2% 

sp 

N 0.00104 2.323 0.1164 2.9% 

S~10 

a -0.0041 3 -4.515 0.1198 -10.8% 

sp 

N 0.00231 2.298 0.0181 6.6% 

SPO 

N 0.0000 172 1.684 0.4424 0.05% 

*The scale of the abscissa in fig. 19 is s uch that January 1974 = 1 and 

December 1981 = 96. 

tS.E. = standard err or. 

except for MLO, for which only 0000-0800 LST data were used to avoid possible 

local contamination from the upslope wind. A linear least-squares trend analysis similar to that given in last year's Summary Report (DeLuisi, 1981) was 

applied to the same data set updated by the 1981 data. The trend lines are 

shown in fig. 19, and the trend analyses are given in table 12. 

Long-term trends are generally less pronounced in this year's analysis 

than in la st year's, especially for BRW and SMO light scattering. In each 

case, an additional year of data made a large difference in the trend. Furthermore, in all cases the trend from the beginning nto the end of the record 

is smaller than the standard error of the data about the regression line. 

General discussions of the annual cycles (or lack thereof) and other 

features of the data given in fig. 19 have appeared in the last several GMCC 

Summary Reports. Of note are the current years of SMO and SPO lightscattering data after rather long periods of instrument downtime. Figures 20 

and 21 give a more detailed presentation of SMO and SPO aerosol data for 1981. 

SMO data continue at approximately the same level as in previous years and exhibit negative Angstrom exponents as before, suggesting a marine aerosol with 

a narrow size distribution. SPO light-scattering data show a minimum in April, 

and the austral winter is dominated by events similar to those first seen in 

45 
·+-----+---~~--_+----_r---- ----+_----~--_+----_r----~----+_----t 

~+_--+_--+_--+_--~--~~I~~---JI---~--~I--~--_+~ ~N < ----+---~--~----+_--_+----IL---4_--------~--~---~----+ N 

~ +----r--~----+_--_t----~--~--_+---- --_r_._+!----t_--_t :;i - I ,I~ il. II , °t-----r----l-~~~~~~rd~~"'ct~~~~ ~~~~flf1~vA~~~At° ,L-__ -L __ -l~~~,~··~··_'·~~·~~ .. ~· !V~.~~~·~:,~~LI~ .. ~.~ .. ~·~ .. ~,~~.~.~.'~~_'._·~·~~ .. .. ~V_·L ~,'~~·~.~~.:_·_·~~' ' 

7.-----r_--_,-----,----_r --._----r_--_,----~----_r----._----,_--__r~ 

, • • 

E , 

.. 

'" 

.. " ~ 

...J ' 

~ 

~L-----L---~-----L-----L----~----L-----L---~-----L----~----L---~ ~ 

• 

M 

, ~ 

E 

u 

z 

V 

"" ON 

...J 

~ 

JAN 

I , 

1 

Wi ,;~ ~4'J(1 ~ I hA \J\\\'v/\l\,~ "'''! 1)1/-,,1 / Iv." /" I~' V\V' • 1'1)1 ,\ 

\ 

,t V" ~rl,\JI/ ' 00 ' " I[ , I' " 1 

I I I I 

I 

, I 

I I 

PEB MAR APR ~lAY JUN JUL AUG SEP 

MONTH OP THE YEAR 1981 

OCT NOV 

Vvi4l 

DEC 

Figu.e 20,--Daily geomet.ic mea n eN concentrati on (bottom), fourwavelength light scatte ring (mi ddle), and Angst.om exponent (top) fo. 

1981 at SMO. For eN, the solid line is G.E. eNC data and the s quares 

are Pollak eNe data. For light sca ttering, 450-nm data are dotted, 

550-nm data are solid, 700-nm data are dashed, and 850- nm dat a are 

long-dashed. For Angstrom exponent, a12 i s dotted, a23 is so lid, and 

a 3 4 is da s hed. 

the 1979 data (GtICC Summary Report for 1979, Herbert, 1980). These events 

most likely are caused by the transport of sea sa lt in the troposphere from 

coasta l .egions of the Anta .ctic continent. A s ummary of monthly geometric 

me a ns of light sca ttering and CN conce ntration for al l sta tions is given in 

table 13. 

Figure 22 illustrates representative distributions of aerosols as a 

fun c tion of wind direction a t the four GMCC stations. Each wind rose gives 

wind frequenc y and annua l geometric mean val ues of CN and light scatte ring 

for 36 wind direc tions. In general, it is expected that eN dat a will be mo re 

46 
'" :!ON 

0-

....l-

<: o 

- G 

E ' 

e; 

o 

"" o~ 

....l ' 

" , N 

E 

u 

z 

u 

"" 0-

....l 

o 

1y 

I-' 

JA)I 

V\ . /\ I 

V. J . I ;\ I' "- " \ r\/ ,1\; J Vi -, ~ I / '. 

I 

I I 

I 

A 

~~ AI I ~! 

~ ..!. i 

\ 

\ \, I~' . ,:':': ' ,I \ \ , '/,' 1 ' 'J -

/' II .J " ~.i \, J \ ~/ 

\',,'/ \ " I,' 

I 

V\A \,!\ 

'IN ~)~ 'I ~~ I

lfI\ )\f'-/V 

ii, 'I r\ "1\ ' llwi\t""'" 

I I I 

Ii \ I , 

f EB ;IAR APR MAY J UN J UL AUG SEP 

\IONTH or THE YEAR 19BI 

I 

! '\ j - I . 

I 

r 

v- i 

\.:';: 

r~ JJ Ii ,A~ IV/ '1/;'1'11 8 " 

° 

OCT NOV 

: 

, 

, 

° ("D.j 

",,-0 

° 

DEC 

o 

, 

~ , 

G 

, 

~ , 

o 

Figure 21.--Dai ly geometric mea n CN conce ntration (bottom), fourwavelength light scattering (midd l e), and Angs trom ex ponent (top) for 

1981 at SPO. For CN, the so lid line is G,E, CNC data and the s quares 

are Pollak CNC data, For light sca ttering, 450-nm data a re dotted, 

550- nm data are solid, 700- nm data are das hed, and 850-nm data are longdashed. For Angstrom ex ponent, a 12 is dotted , a2 3 i s solid, and a34 is 

dashed , 

sensitive to local pollution sources. A representative year was chosen for 

eac h station. 

The BRW CN data clearly show the direction of the village, whe reas lightscattering data appear not to respond to the village, MLO CN and light scattering both r e spond clearly to toe upslope wi nd , and i n add ition, small peaks 

are evident when the wind is from the Mauna Loa caldera (about 200 0 bearing 

fwm MLO). SMO CN and light sca ttering are both higher to a small deg ree when 

the wi nd i s from the island (SW) tha n from the ocea n, South Pol e data clearly 

s how the effects of winds from the camp (SW) , 

47 
Table 13. --~Ionthl y geometric means of light-scattering a nd 

CN da t a for 1981 at all GNCC stations 

tlonth a m- 1 eN cm- 3 S!, 

450 nm 550 nm 700 nm 850 nm 

(x 10- 6 ) 

BRIY 

I 12.9 12 . 5 8.93 6.73 5 14 

2 12.2 11.2 7 .58 5.54 316 

3 10. 7 9.89 6 . 73 4.95 185 

4 10.4 9.03 5 .49 3 . 57 217 

5 4. 75 3 .82 2 .1 8 I. 38 140 

6 I. 78 I. 47 0 . 839 0.567 133 

7 2.4 1 2.26 1.7I 1. 36 364 

8 1. 26 1. 13 0.869 0.739 286 

9 2 . 63 2.43 I . 86 I . 41 132 

10 5.05 4. 53 3 .1 6 2.26 88 

II 15.0 13.9 10.6 7.82 237 

12 28.5 27. 1 20. 1 15.5 254 

tlLO 

I 0.471 0.336 0.183 O. lI8 195 

2 0.154 0 . 150 0. 10 1 0.0949 239 

3 1. 37 1. 00 0 . 927 0.684 195 

4 2. 13 I. 68 1. 22 0.9 16 242 

5 I. 54 I. 35 I. 19 I. 11 252 

6 190 

7 294 

8 293 

9 32 1 

10 335 

II 241 

12 284 

SflO 

I 329 

2 447 

3 15.0 14.3 15.3 17.3 451 

4 15. 8 14. 7 15 . 3 17 . 2 317 

5 12.4 11. 8 12.8 14 . 7 25 1 

6 16 . 2 15. 8 17 . 3 19. 5 305 

7 13.2 13.0 14.3 16. 3 405 

8 10 .4 9 . 75 10 . 2 11. 2 366 

9 15.2 13.8 14 . 1 15.4 367 

10 16.7 15. 7 16.3 17.7 323 

II 9 . 45 8 . 87 9.36 10.5 381 

12 11. 0 10 . 4 11. 1 12.4 440 

SPO 

1 0.403 0 . 278 O. 117 0.0565 139 

2 0. 362 0 . 208 0.0986 0.0618 144 

3 0.237 0.134 0 . 0705 0 . 0473 98 

4 0.326 0.220 0 .1 54 0. 123 35 

5 0.252 0.184 0 . 126 0. 102 25 

6 0.309 0.249 0.172 0 .1 41 11 

7 0.378 0.343 0.207 0.150 15 

8 0.265 0.208 O. 127 0.0962 16 

9 0. 378 0.297 0.205 0.158 29 

10 0.403 0.323 0.218 0.178 62 

11 0.459 0.397 0.288 0 . 236 145 

12 0.293 0.185 0.0998 0.0654 137 

48 
W,nd fnoq. Lot; Sudr i 

'." .. .. m- ~ 

'" 

'< , 

'0 

< 

\r E 

• 

". ./ " 

" BARROW Loc gf" , ... 

Tolel Hou,. - ~ S . ~nrn 

N Wind rn q. Lot; Sud i 

'." ,m , • 

'" .-.,. . 

'< -.., 

'0 

< , 

W E 

" SAMOA Lal fI,. 

"" 

Tolel Hou .... . ~ s A_ :I6Onm 

W,nd r req. 

'." 

'" ~ 

'0 

w 

WA USA LOA 

"'" To\al Hou ... . 8524 

'fInd r~. 

'." 

'" 

'< 

'. 

W 

SOUTH POL 

,~, 

N 

< , "»'y!t 

~ 

N 

< ~'" 

" 

- .. --

s 

• 

• 

'. 

Lal Suel .. i , , ,m 

E 

~nm 

E 

Figure 22.--Annual geometri c me an CN concentration (solid), 550- nm light 

scatt ering (dashed), and wind frequency (cente r bars) for BRW, MLO, SMO, 

and SPO, all as a function of wi nd direc t ion displayed on a 36-point 

wind rose. 

3 .9 Sol ar Radiation 

3.9. 1 Introduc tion 

The GMCC solar radiation monitoring program consists of continuous and 

discrete measurements of several short-wave radiative quantities at the four 

base line stations . The major components of the ground-based observi ng program 

have been in qua si-continuous operation since 1975 -19 76 . Oc casional data 

losse s have occurred primarily as a result of data acquisition computer downtime, but also as a result of ca librations, obstructions to instrument field 

of view, so lar tracking erro r s , and misce llaneous instrument failures. Some 

49 
Table 14.--Abbreviations for filter passbands of 

solar radiation instruments 

Abbreviation Filter 

Q Quartz, 280 < A < 3,000 nm 

GG22 Schott glass, 400 < A < 3 ,000 nm 

OGI Schott glass, 530 < A < 3,000 nm 

RG2 Schott glass, 630 < A < 3 ,000 nm 

RG8 Schott glass, 695 < A < 3, 000 nm 

data losses are recoverable from the strip chart backup data-recording system 

but this is not routinely done . A nearly daily (5-7 days a week) documentation of the operation of the solar radiation instrumentation is maintained by 

the station personnel. 

3.9.2 Instrumentation and Data Acquisition 

A detailed summary of the initial instrument arrays at each station is 

given in the GMCC Annual Report for 1976 (Hanson, 1977). Additions and deletions to these instrument arrays are chronicled in subsequent GMCC annual reports. Table 14 gives the abbreviations for all of the filters used in Eppley 

solar radiation instruments in the GMCC program. The monitoring instruments 

as of December 1981, operating at the baseline stations, are given in 

table 15. 

Table 15. --Solar radiation monitoring instruments, December 198 1 

Ins trument'" Station Comments 

BRW ~lLO SMO SPO 

Eppley pyranometer 

Q X. X X X Continuous 

RG8 X X X X Continuous 

OGI X Continuous 

Epp l ey pyrheliometer 

Q X X X Continuous 

RG8 X Continuous 

Q X X X X Discrete 

OGI X X X X Discrete 

RG2 X X X X Discrete 

RG8 X X X X Discrete 

Sunphotometer 

380 nm, narrowband X X X X Discrete 

500 nm, narrowband X X X X Discrete 

Shaded pyranometer X 

Solar IR hygrometer X 

,'·See table 14 for abbreviations . 

50 
Table 16.--Calibration constants for solar radiation 

monitoring instruments 

Ins t rumen t Type-:: 

serial 

numbe r 

12263 

12267 

139 13 

126 16 

10153 

211 9 

139 10 

12502 

126 19 

11946 

133 14 

12271 

12269 

12270 

296S 

13912 

12617 

13909 

G 

G 

Nt 

G 

G 

NT 

Nt 

SG 

G 

NT 

NF 

G 

G 

G 

NT 

Nt 

G 

NF 

Filtert 

Q 

RGS 

Q,OG I, 

RG2,RGS 

Q 

RGS 

Q 

Q,OGI, 

RG2,RGS 

Q 

RGS 

Q 

Q,OGI , 

RG2,RGS 

Q 

OGI 

RGS 

Q 

Q,OGI , 

RG2,RGS 

Q 

Q,OGl, 

RG2 , RG8 

St ation 

BRJ,.,' 

BRW 

BRW 

1110 

LO 

NLO 

mo 

1110 

S~ O 

S~ O 

SNO 

SPO 

SPO 

SPO 

SPO 

SPO 

Ba s i c 

cal i bra tion 

IPS§ 

(mV mW-} cm2) 

0 . 0956 

0 . 0965 

0. OS29 

0 .0794 

0 .0767 

0 .0295 

0 .0825 

0 . 0952 

0. 079 1 

0 . 08 10 

0 .0829 

0 .1072 

O. 1036 

0 . 0978 

0.0259 

0 . OS 15 

0 .08 10 

0 . 0774 

Zero 

o ffse t 

(V) 

-0 .020 

+0 .007 

NA 

- 7 . 997 

- 7 .996 

- 7. 983 

NA 

-S. 095 

- 4 .902 

- 4 .988 

NA 

-7. 896 

- 7.9 49 

- 7.802 

- 7. 9 12 

NA 

NA 

NA 

ICDAS 

Sca le Ch. 

f ac tor 11 0 . 

(mW cm- 2 ) 

11. 51 16 

I I .4S 19 

NA NA 

12 .585 16 

13 . 03 1 19 

33 .824 2 1 

NA NA 

10. 62 1 24 

12 .526 19 

13 . 669 21 

NA NA 

9 .21 3 16 

9 . 42 1 IS 

10 .085 19 

38 . 72 21 

NA NA 

Comments 

Online 

9/ 81 

NA 

NA 

NA Tra ve ling 

s tanda rd 

NA Trave l i ng 

s t andard 

*Typp: G-- g l obal pyranomete r; NT --NIP, continuous t ra c ki ng ; SG --s hade d py ranomete r; 

NF--NIP filter wheel , hand held. 

tSee table 14 for abbrev i ations. 

§TPS ; International Pyrheliometric Sca l e . 

Nole: For absolute ra diation scale , div i de basic cal ibra tion by 1. 026 o r mult i ply sca l e 

[actoL' by 1. 026. 

Ta ble 16 gives the curre nt ca l ibration information for most of these instruments . The ) CDAS constants take into a c count amplified instrument signals 

and a ze r o of fse t used by I CDAS. Radiation quantities in engineering units 

(mW cm- 2 ) can be ob t ained from the ICDAS-recorde d minut e -averaged voltages by 

means of 

EU = (V - OS), SF 

where EU = engi neering un its, V = r eco rded voltage, OS = offset voltage, and 

SF = sca l e f actor . The ICDAS constants vary slightly with time and a re 

r outi ne l y mon itored , but l ong-term changes ( except for amplifier r eplacements) 

a r e l ess tha n 0 . 1%. 

51 
Table 17.--Field instrument intercomparison wi th traveling s tanda rd1' 

Station Inst. 1976 1977 1978 1979 1980 1981 

typet 

BRW G 0.994 0.997 1. 014 1.0092 

BRW NF 1.0039 1.0038 1.0058 

MLO G 1.0016 1. 0031 1.0041 1.0091 1.0081 1.0069 

MLO NF 1. 0071 1.0097 1.0056 1.0016 1.0089 

MLO NT 0.998 1 . 0079 1.0039 1.0054 0.9975 

SMO G 0.990 1.010 1. 0216 1.0343 1.0494 

SMO NF 1.011 1. 0123 1.0075 1.013 

S~ O NT 0.989 

SPO G 0.9905 0.9961 0.9870 0.985 

SPO NF 0.9978 0.9959 

SPO NT 1.0706 1. 07§ 1 . 07§ 1.07§ 

,"Ratio of standard instrument to station instrument. 

tSee tabl e 16 for abbreviations. 

§Comparison between station NF and NT. 

Note: All instruments have quartz filters. 

3.9. 3 Ins trument Inte r comparis on and Inte r calibration 

The bas ic instrument calibrations, originally supplied by the manufacturer, are monitored in two way s : intercomparison with similar instruments at 

the station and inter comparison with GHCC-maintained traveling standard instruments. The traveling standards are in turn intercompared with instruments 

mainta ined in Boulder and inte r calibrated by the NOAA Solar Radiation Faci lity. Only the nonspectral pyranome ters and pyrheliometers are intercompared 

and intercalibrated in this manner. Calibration of the broadband spectral 

instruments depends on a combination of a nonspectral calibration of the instrument sensor and a filter factor. Narrowband spectral instruments can be 

self-calibrated using the Sun as a constant source, but they generally ha ve 

had a calibration transferred from a reference instrument. 

A summary of the intercomparison ratios between t he traveling standards 

and the station quartz pyranometers and pyrheliometers is given in table 17 . 

The ratios are obtaine d from side-by-side measurements over the period of 

several days, which result in several thousand simulta neous measurements per 

comparison for the pyranometers and 20-40 points for the pyrheliometers. The 

only departure significantly greate r than 1% over the 6-yr record is for the 

pyranometer at SMO that was replaced at t he end of 1981 beca use of its apparent calibration drift. The affected data at SMO were corrected for this drift 

before being arch i ved. 

3.9.4 Pyranometer Data 

Solar radiation data can be summarized and presented in numerous way s . 

The generally known dependency of s urface-received solar radiation on highly 

variable quantities such as s olar position, time of day, time of year, amount 

and type of cloudiness, and surface albedo, in addition to atmospheric composition, makes straightforward presentation of all the GMCC data impractical 

here. 

52 
Table 18.--Honthly average of daily total received so lar radiation 

on a horizontal s urfa ce x 10 3 kJ m- 2 absolute sca l e'" 

SRI' mo StlO SPO 

Q RG8 Q RG8 Q RG8 Q RG8 

1979 

J 0.07 0 . 0 19 . 7 10.4 20.8 10. 1 32.8 16.9 

F 0 . 94 0 . 47 16.5 7 . 75 22 .7 11. 7 19 . 1 11.0 

tl 6 .03 3 . 06 25. 1 13 . 3 21.6 10.7 3.74 2. 16 

A 13 . 8 6 . 86 27.0 14. 9 17 .6 8.91 0.0 0 .0 

tl 19. 6 8 . 86 28. I 15 .1 16.2 8.21 0.0 0.0 

J 20 .1 9.68 28 . I 15 .4 14.8 7.60 0.0 0.0 

J 18 . 3 8.49 27 .3 14 .9 15.0 7 .44 0 . 0 0.0 

A 8.2 3.98 27 . 3 14 . 8 19.4 9.85 0.0 0.0 

S 4.9 2 . 29 24.2 13 . 2 19.2 9.66 1. 32 0.82 

0 1. 09 0 . 44 17.3 9 . 32 18.2 9.00 10.7 5 . 66 

N 0.125 0.06 17.5 9 . 02 23.0 11.5 28 .4 14. 5 

D 0.00 0. 0 17.8 9.83 20.5 9 . 93 35. 1 17 . 8 

1980 

J 0.019 0. 01 19.8 10. 6 9.4 8.96 32 . 0 16 . 6 

F 0.896 0.4 3 23.9 12 .4 19.4 9.57 16.7 9 . 17 

t1 5 .19 2 . 98 18.5 10 . 3 20.8 9 . 92 5.26 3 .48 

A 13.6 6.49 29 .3 15 . 2 17.2 8.26 0.0 0.0 

t1 20.0 8.39 26.0 13 . 8 12.7 5.96 0.0 0.0 

J 21. 3 9.54 26.7 14.5 12 .8 6.03 0.0 0.0 

J 15.5 7.67 24.6 13 . 3 14.7 7 . 00 0.0 0.0 

A II t1 27.4 15.0 14.4 6 . 67 0.0 0 .0 

S tl tl 21. 7 11. 7 17 . 0 8 . 23 1. 82 tl 

0 1. 71 O. /3 21.5 12.3 18.0 9 . 44 10. 2 5 .45 

N tl II 2 1. 6 12 .0 20 . 8 10. 3 27 . 8 14. 2 

D 0.00 0.00 19 . 6 11. 0 23 . 6 10 .5 36.9 18 . 5 

1981 

J 0.064 0.0 21 .0 II. 9 20.2 9 . 62 31.1 15 .8 

F 0.911 0.46 23.7 13.3 20.6 9.88 19.3 10.1 

tl 5 .90 2 . 89 27 .0 15 . 2 19.4 9.32 tl II 

A 13.2 6 . 30 26. I 14.5 14 . 2 6.58 0.0 0 . 0 

t1 18.7 8.39 30.3 16.9 15.3 7 .1 9 0.0 0.0 

J 21. 2 9 . 92 29.8 16.5 14.5 7.06 0.0 0 .0 

J 13 . 9 6.49 29.6 16.5 16.7 8.09 0.0 0.0 

A 11. I 5 .1 6 26.9 14 . 8 17 . I 8. 15 0.0 0.0 

S 4.87 2.29 23.7 13.1 19.5 9.35 1. 44 0 . 77 

0 1. 52 0.93 22 . 2 12 .6 18.5 8 . 62 12.0 6.50 

N O. 18 tl 19.4 11. 5 19. 7 9 . 22 28.2 14 . 5 

D 0 . 00 0 . 00 19 . 2 10 . 8 20.0 9 . 65 34 .0 15 . 4 

"'See t ab le 14 for filter abbreviaLions. 

Note: N = missing da ta. 

Examples of several days ' worth of minute-by -minut e pyranometer data were 

given i n the mlCC Summary Report for 1979 (Herbert, 1980) . Py ranometer data 

are being a rchived on a yearly ba sis at NCC. These data are a rchived as hourly integrals of total energy received in the Researc h- Coope rator format. None 

of the known sources of variability were removed except some instrumentrelated errors . The data are not correcte d for possible instrument errors due 

to cosine respons e or ambient t empera ture variations, however . A summary of 

the archived pyranometer data for 1979-198 1 is given in t able 18. Prior t o 

1981, OGI and GG22 pyranometer dat a were a lso archived. 

53 
Table 19.--Pyranometer ra tios averaged fo r 1979-1980 

Station GG22/Q OGI/Q RG8/Q 

BRW 0.913 ± 0.015 0.716 ± 0.033 0.474 ± 0.046 

HLO 0.958 ± 0.028 0.746 ± 0.029 0.544 ± 0.033 

S~IO 0.918 ± 0.013 0.714 ± 0.026 0.483 ± 0.032 

SPO 0.925 ± 0 . 021 0.702 ± 0 . 03 1 0 .5 14 ± 0.031 

The spectral res olution of the archived pyranometer data ca n be demonstrated by taking the ratios of the va lues from the cutoff fi lters to the 

values from the quart z pyranometer. These ratios averaged for all of 1979 and 

1980 hour by hour for all-sky conditions are given i n table 19. The indicated 

range is one standard deviation; the number of points is about 6,000 for eac h 

ra tia. 

Temporal variations in the ultraviolet spectrum would be reflected in the 

GG22/Q ratio whereas changes in the solar infrared r egions a re reflected in 

the RG8 /Q ratio. Ozone and water vapor are the two main atmospheric constituents responsible for variations in the UV and solar IR, respectively. A more 

quantitative analysis of these ratios would be complicated by t he presence of 

cloudy and diffuse sky as well as by variable path length data included in the 

averages. 

3 . 9.5 Pyrhel iometer Data 

Pyrheliometer measurements of the direct sun intensity normal to the 

light path are made for a more complete picture of the nature of solar radiat ion reaching the Earth's s urfa ce. The meas ured direct radiation is a single 

component of the total radiation mea s ured by the pyra nome t ers. Pyrheliometer 

measurements are useful in determining the c l oud-free atmospheric influence on 

surface-based solar radiation mea s ur ements . Unlike the total or all-sky measurements o f the pyranometer, the pyrhe liomet e r meas uremen t s can be reduced to 

remove nearly all of the known sources of va riabil ity except for those due to 

atmospheric compo sition and to the variability of the output of the Sun itself. Figure 23 shows a 5-yr summary of broadpand fi lter wheel NIP data on 

the absolute radiation sca l e corrected t o 1 A.U. f or each station. Each point 

plotted, with the number of observations and sta ndard deviation, is the average of all data falling within a 0.2 relative air mass (HR) interval. These 

measurements are normally made 2-3 time s per day, s ky cond itions permitting. 

Better time resolution in the pres entation of these data would be necessary 

for de tailed discussion, but they are presented in this ma nner as a s ummary 

and for use as reference levels. The de crease in intensity with decreasing 

air mass at HLO is attributed to local diurna l cycles in water vapor and 

aerosols. 

The continuousl y tracking and r ecording pyrheliometers at the baseline 

stations permit the calculation of a relative atmospheri c transmission factor , 

after the technique of Ellis and Pueschel (1971). The technique uses the ratios of the measured solar intensity at consecutive-integer rela tive air 

masses, and averages thes e ratios for a given morning or afternoon. The air 

mass values traditionally used are 5 , 4, 3, and 2. The resulting transmission 

54 
BARROW 

T r--. ¥ Ii , .--.--••• 

Of\1.0 12 ~ 1.6 18 10 2.2 2 I 2.6 2.8 ]0 ].2 '1" 1,6 1. 8 i _O ". 

SAMOA 

" 

•• m MAUNA LOA 

811; 142 18 

O~"'810 

l-~ 

'" r-+-- 1 

",]--+-1 

SOUTH POLE 

" 

0.8 to ,'.2 ,'. 4 {6 ,'. a /0 2'.2 2' . • 2'.6 { S J'.o ]'. 2 ]'. 4 ]'.6 ]'.8 / 0 

". 

Figure 23 .--Direc t irradiance ave raged for 1976- 1980 for f ilters Q, OG1, 

RG2 , a nd RG8 at (a) BRW, (b) HLO, (c) S~lO, and (d) SPO. Variability 

bars show one standard deviation. The number of observations i s given 

along the bar for each indicated air mass i nterva l. 

fa c tor or apparent transmission is independent of instrument calibra tion, independent of instrument drift on time scales longer than one day, independent 

of the extraterrestrial irradiance, but dependent on air mass. As a long-term 

moni to r o f relative atmospher ic transmission, the paramet e r is comp ared day t o 

day at the same air mass valUeS. Of the fo ur baseline stations , only HLO has 

proved suitable for t he long - term calculation of the apparent transmission 

f ac t or. Analysis of t he long-term record a t HLO, starting in 1958 , has been 

given by Hendonca et al. (1978) and Bodhaine et a l. ( 1981b). 

The 1980 and 1981 mon thly average values of HLO apparent transmission are 

presented in table 20 . Beginning i n Harch 1981 the value s are derived by computer f rom t he data recorded on magneti c tape at the st ation. Visual inspec -

tion of t he strip chart records is sti ll r equired to ensure that only cloudfree days are used in the ca l culation. A careful comp aris on was made between 

the computer-derived values and t he previously hand-determine d va lues to ensure consi stency o f t he record . 

55 
Table 20. --MLO apparent atmospheric transmission 

(morning only) 

Hand ca l culated Compute r calculated 

1979 

Sep 

Oct 

Nov 

Dec 

1980 

Jan 

Feb 

Ia r 

Apr 

May 

Jun 

Jul 

Aug 

Sep 

Oct 

Nov 

Dec 

198 1 

Jan 

Feb 

Mar 

Apr 

~Iay 

Jun 

Jul 

Aug 

Sep 

Oct 

Nov 

Dec 

*Less than five days . 

tEdited data. 

3.9.6 Specia l Projects 

0.933 

0.929 

0.924;' 

0.933 

0 . 935 

0. 934 

0.931 

0.925 

0 . 923 

0.927 

0.929 

0.928 

0.931 

0.932 

0.930 

0.931 

0 . 933 

0.934 

0.927 

0.929 

0.932t 

0.930 

0.929 

0.930 

0 . 93 1t 

0.929 

0.931 

0. 933 

0.931 

0 . 927 

0.929 

0.926 

0.929 

0 . 929 

0.930 

0.929 

0.931 

0.93 1 

During 1981, a nd ex tending into 1982, several special projects were undertaken by the GMCC AmI group. Table 21 shows the new or special short-term 

measurements conducted during 1981. Some of these measurements wer e carried 

out f or instrument testing and performance analysis only (Boulder-based measurements). The results of the water vapor meter measurements and an intercomparison of various s unphotomet e rs are reported in secs. 4.11 and 4.12. Data 

from most of the programs indicated in table 21 are not ready for presentation 

at this time. Only the results of the active cavity pyrheliometer measurements at MLO and Boulder are given in the following. 

An Eppley Kendall ACR is a self-calibrating radiometer directly comparable with the Eppley NIP's because of their equal fields of view a nd calibrated spectra l ra nges. The absolute accuracy of the ACR is limited only by 

56 
Table 21 .--Experimental and event measurements 

BRW HLO SHO SPO Boulder Whiteface 

Ht. , N.Y. 

Eppley narrowband & X 

broadband NIP 

(13 channels) 

Spectral albedo X X 

Spectral diffuse X X X X 

s ky /direc t solar 

Spectral extinction X X X X X X 

Total H2O X X X 

Active cavity X X 

pyrheliometer 

the geometry of the optical system and the ability to measure voltage and current. International intercomparison of these instruments has shown that instruments of different design and manufacture all agree to within ±0. 5%, and 

most agree to ±0.25%. 

GHCC Epp l ey Kendall ACR no. 12843 was comp ared with THI ACR no. 67502 of 

the NOAA Solar Radiation Facility on 31 December 1980 and 6 April 1981 . ACR 

no. 67502 is the primary standard of the calibration facility and ha s participated in many internationa l ACR i ntercomparisons held i n Davos, Switzerland . 

The 31 December comparison s howed a 0 . 003% ± 0 . 026% difference between the two 

instruments. A sensitivity of ACR no. 12843 to air currents was observed dUring the intercomparison, and some obviously affected data were removed when 

compiling the comp arison ratio. 

Before the 6 April intercomparison, an insulating jacket and sun s hade 

were fitted to the mlcc ACR. These additions appeared to greatly reduc e the 

air current sensitivity of the instrument. The 6 April intercomparison showed 

a 0.020% ± 0.011% difference, essentially unchanged from the 31 December 

comparison. 

ACR no. 12843 was sent to ~ILO for long- and short-term intercomparisons 

with the tracking NIP no . 2119. (The ca l i bration constant of the NIP was 

0.0288 mV mW- 1 cm2 on the absolute scale.) The results of the monthly average 

difference between these two instruments are given below. 

ACR - NIP x 100 

ACR 

Jun 0 . 40% ± 0.16% 

Jul 0.58% ± 0.20% 

Aug 0 .59% ± 0 . 14% 

Sep 0 . 44% ± 0.18% 

Oct 0.60% ± 0.09% 

Nov 0.67% ± 0.17% 

De c 0 .40% ± 0.10% 

Average 0.53% 

57 
These data represent excellent agreement between a quartz-window, normal incidence pyrheliometer and an ACR, especially in the relative sense where the 

month-to-month variabil ity was le ss than 0.3%. However, most of the compari -

son measurements were taken near midday so the ag reement cannot be projected 

over an entire day. These measurements are continuing in an effort to maintain the current ca libration of the MLO NIP and to back-calibrate the entire 

26-yr NIP record for MLO. 

Late in 1981 plans were initiated to deve lop a semiautomated solar observatory at MLO. . The observatory will be housed in the 16-ft As h Dome cUrrently housing the MLO l idar, which will be moved to a new building. The observatory dome will house a precision active so l ar-t racking spar, data acquisition system, several radiometers, and a semi automated dome control l er . The 

observatory is expected to be put into operation in late 1982. A prototype 

observatory will first be operated in Boulder. 

The high-spectra l -resolution atmospheric transmission model, LOWTRAN 5 . 0 

(Kneizys et al., 1980), has been combined with an extraterrestial solar intensity spectral curve to aid the theoretical calculation of surfa ce-received 

direct solar radiation at GMCC stations. The SOLTRAN (LOWTRAN and SOLAR 

SPECTRUl'l) model along with a nonspectral model of diffuse and direct solar 

radiation (Bird and Hulstrom, 1981) have proved useful in data quality control 

and research . 

The design adaptation and fabrication of a h igh-precision threewavelength sunphotometer was begun by the ARM group in late 198 1 . The design 

is basically that provided by C. Frohlich, which satisfies WMO's recommendaLions for iIlsLrwueIlLs that measure background levels of turbidity or optical 

depth. Current plans call for this instrument to be used as a standard 

against which all narrowband spectral measurements at Gl'lCC will be referenced. 

The instrument will be tested and calibrated at the new so l ar observatory facility at ~lLO. 

Several designs of a narrowband spectral radiometer ha ve been tested in 

an effort to measure the ratio of diffuse sky flux to direct solar flux. Measurement of this rati o permits determination of the aeroso l absorption occurring in a sufficiently optically thi ck event. The diffuse component can be 

either the global (2IT) field or a narrow (few-degree) field, with the resulting absorption determined by observational agreement with radiative transfer 

models. The diffuse/direc t radiometers have been or will be used in fie l d 

programs at BRW, MLO, Boulder, and Whi teface ounta . 

3.10 Station Climatology 

3.10.1 Instrumentation and Data Processing 

A description of meteorological instrumentation and da t a processing 

appears in last year's Summary Report (DeLuisi, 1981). ~leteorologica l data 

from the GMCC stations are stored in tabular form on microfiche and on magnetic tape. The listings on microfiche are organized by station, date, time, 

and variable . The hour l y average value s, sca l ed in metric units, for a single 

GMT day, are listed on a single frame . The variables i nc lude resultant wind 

direction and speed; station pressure; and air, ground, and dewpoint temperatures. Listings of data on microfiche are avai l ab l e 6 months following t he 

58 
end of the year. 

a large volume is 

3 . lO . 2 Ba r row 

Data are also stored on magnetic tape and ca n be s upplied if 

needed. 

BRW is located about 9 km southwest of Point Barrow on a smal l rise in 

t he tundra between two saltwater lagoons. With the Ar c tic Ocean to t he north, 

east, and west, and relatively leve l tundra stretching more than 200 km to the 

south, there are no local topographi c barrie rs to red irec t the wind field . A 

uni form snow and ice cover hides the Alaskan shoreline for 8 months of the 

year. Except for stormy periods t hat bring westerly winds, t he surface winds 

are generally northeasterly in response to the general circul a t ion around the 

two dominant continental high-pressure regi ons in the Arctic. A low- l eve l 

inversion (0 . 1-1 km) separates the more easterly surface winds from mor e 

northerly winds aloft (Hiller, 1981a ). In a r ecent study of the wind clima -

tology a l ong the Alaskan North Slope, Kozo ( 1980) found evide nce of a turning 

of the wind in the surface layer as the res ult of a ba roclinic e ff ect caused 

by the Brooks Range to the south. The effect is s uch that east of BRW, where 

the mountain barrier is c los e to the coast, the winds are turned to the south, 

whereas at BRW s urface winds are northeasterly. Surface wi nd s du ring the summer months are influenced by a loca l sea breeze a long the Beaufort Sea (Kozo , 

1979) . 

The histograms of the hourly average resultant wind speed as a function 

of direction (fig . 24) f or 1977-1980 and for 1981 s how exce llent agreement. 

Exc ep t for the predominance of the five most easterly directions, the dis tribution is surprisingly symmetrical . For the period 1977 -1 980 , easterl y sector 

winds (NE, ENE, E, ESE, and SE) occurred 55% of the time , whereas for winds 

BARROW 

., 

w 

W1SD SPEED (W/ S) 

_ ~, .. s<~ 

C<Z:lI ~ " WS < 10 

c::::J U i" 10 

N 

s 

• 

~ 

111SD flIEQ 

, 

E 

BARROVt' 

77- 80 

w 

'11'1 ND SPEUl (W/ 5) 

_ $t .. ~ 

I"==:J $ 1i -'.'1 < 10 

0 -..'1 llO 

N 

s 

~ 

" ISO f'REQ 

, 

Figure 24 . --Wind rose of s urfa ce winds fo r BRW for 1981, left, a nd 19 77-

1980, right. The distributions of the resultant wi nd direction a nd 

speed are i n units of percent occurren ce for the year and 4-yr period , 

respectively. Wind sEeed is shown as a function of direction in three 

s pe ed classes. 

59 
Table 22. --1981 BRW monthly climate summary'·' 

J,n Feb Apo ay Jun Aug Sep 0 « Nov Deo 

Prevail ing wind ENE EnE ENE E ESE E W ENE ENE EKE ENE E~~ 

di rection 

Average wind 6.3 6.0 6 7 4 . 4 5 . 3 5.0 5 3 4.6 4 8 6.1 5.7 5 . 8 

speed (m s - 1) 

Maximum wind 14141810 12 11 1311 II 16 19 15 

speedt (m s -I ) 

Dire cti on of max. 85 95 95 110 3 10 70 195 255 50 85 85 70 

windt ( deg.) 

Average station 1002.1 10 163 10144 101 58 1014. 7 1010.1 10139 1007 . 9 1012 . I 101 3.8 1009.1 10090 

pressure (rob ) 

Maximum pressuret 1025 1044 1033 1042 1029 1019 lOIS 1030 1028 1030 1026 1041 

(mb) 

~linimum pressuret 986 993 1000 99 5 993 999 983 992 998 1002 989 975 

(mb) 

Average air -18.6 - 26 . 2 - 23.5 -17. 2 - 4 .1 0.9 4.1 3 .6 - 35 -9.1 -185 - 23. 4 

t empe ra lure (Oe) 

Maximum temperaluret -r -1 0 - 8 0 3 12 17 15 6 - 2 - 5 -9 

(0e) 

Ninimum temperaturet - 33 - 38 - 38 - 32 -1 7 - 4 - 3 - I -1 2 - 21 - 29 -33 

(Oe) 

-:'I ns t rumen t heights are as f o llows : wind, 16 m; pressure, 9.5 m (MSL); air and dewpoint t emperature, 3 m. Wind a nd 

t empe rature i ns t rume nts are on a t owe r l oca ted 25 m no rtheast o f the ma in building . 

t~la)(im m and minimum value s are ho ur ly averages. 

10 m s-1 or greater the occurrence from this quadrant is 75% (Harris and 

Herbert, 1980) . As in previous years, the prevailing wind is eastnortheasterly, and sometimes northerly and westerly in December. Table 22 

gives a monthly breakdown of average and extreme values of wind, air temperature, and station pressure. The most striking feature in the 1981 data 

summary is the anomalously low pressure and the warm temperature in January. 

The pressure was 12 .5 mb below the 6-yr average e nding in 1981. The January 

temperature was 4°C warmer than the average for the last 6 years. The maximum 

hourly average wind speed was reported in November to be 19 m s-1 Recent 

studies indicate that the station pressures measured with the pressure transducer at BRW are on the order of 2.5 mb low. 

3.10.3 Mauna Loa 

Throughout much of the year the mi dtropospheric winds in the southcentral Pacific are determined by the position of the Pacific anticyclone. 

This is especially the case in the summer months when the anticyclone is in 

its northernmost position and the winds in the vicinity of Hawaii are light 

and easterly. During the winter months the Pacific anticyclone moves farther 

south and diminishes in size, allowing the southern extent of the midlatitude 

cyclones to pass the islands. This period is characterized by a much higher 

occurrence of westerly winds at all levels. In the transition periods between 

these two dominant patterns, stronger easterly winds are commonly observed. A 

recent study of the beginning point of 10-day back trajectories from MLD shows 

this seasonal breakdown (Miller, 1981b). The largest percentage of the trajectories originate to the east of MLD during the summer months and to the 

6D 
MAUNA LOA 

81 

IV 

' INO SPO:O (II I !) 

_ ~" !l ~ 

c::::ZI 'IS <IO 

D I!l~ 10 

N 

s IISD ntEQ 

, 

E 

MAU NA LOA 

77- 60 

IV 

' ISO SPEED (II/ S) 

_ "!l ~ 

c=J~"'<IO 

O 

N 

s 'ISO n l.l;Q , 

E 

Figure 25.--Wind rose for MLO for 1981, left, and 1977-1980, right. See 

legend for fig. 24. 

northwest during winter months. The highest percentage of long trajectories 

(greate st number beginning beyond 2,000 km from MLO) also occurs iI' LI.e winter . Significant year-ta-year va riations are also observed. 

The surface wind (10-m height) measured at the observatory represents a 

more complex flow regime. For much of the time the synoptic-scale pressure 

gradient influence is overpowered by the lo cal influence of surface heating 

and cooling causing a diurnal upslope-downslope flow (Mendonca, 1969; Miller, 

1978). In even more well-defined flow situations , the twin peaks of Mauna Kea 

and ~Iauna Loa redirect the flow. This is illustrated in part by systematic 

differences between the climatology of trajectory source points and the wind 

distribution at the observatory, as in fig. 25. The combined wind distribution from 1977 through 1980 shows a mu ch higher occurrence of winds with a 

southerly component than does the trajectory analysis . While the synopticscale flow pattern is more easterly or westerly, the effect of Mauna Loa is to 

redirect stronger winds from aloft down the slope with a more southerly component. The departure from symmetry in the distribution of the southerly 

winds is to the south-southwest, the exact direction of the summit of ~launa 

Loa. Higher wind speeds (z10 m S-1) occur mo st commonly (80% of the time) 

with stormy periods and are almost exclusive ly confined to the southerly 

directions. Of particular interest is the relatively large frequency of 

occurrence of winds greater than 10 m S-1 from the south-southeast. The 

upslope-downslope winds are generally represented by speeds of 5 m S-1 or 

less. Such conditions occur approximately 62% of the time. Calm conditions 

(wind speed <0.5 m s-1) occur 2.9% of the time on the basis of the 4-yr average. It is of interest to note that the January 1981 temperature at MLO is 

3.5°C warmer than the 6-yr average ending in 1980. Monthly mean a nd extreme 

values for wind, pressure, and temperature are given in table 23 . Temperature 

measurements are made at MLO using instrumentation similar to that at BRW. 

61 
Table 23 .--1981 MLO monthly climate sununary"''; 

J,n Feb a r Apc Ia y Jun Jul Au, Sep 0" Nov Dec 

Prevailing \"ind SW SW SSE SSE NW SE SSE SSE SSE SW SSE SSE 

direction 

Average wind 

speed (m 5- 1) 

5 3 7.6 5.0 4 5 4.9 7.5 4 3 4.4 4 4 3 4 5 0 5.1 

Ial(im um Idnd 15 17 14 13 10 16 12 14 12 12 14 17 

speedt (m 5 - 1 ) 

Direction of max. 260 225 160 150 295 150 155 145 155 355 ISO 165 

\dndt (deg_ ) 

Average station 680 6 679 6 681.1 680.8 681.4 681 .9 68 1 .7 68 1 .9 681.7 681.1 681 .7 680.5 

pressure (mb) 

Maximum pressuret 685 686 685 685 685 686 684 685 684 685 686 683 

(mb) 

~lin mum pressllcet 676 670 678 676 678 679 678 679 678 677 678 676 

(mb) 

.o\vcrage air 3 6.0 5 . 8 6 .1 9 2 9 3 9 .9 8. 8 . 0 7.4 7.2 6.0 

temperature COe) 

tlaximum tempe ra t u ret 16 16 15 18 18 21 20 19 17 16 17 15 

(0e) 

tlini mum temperatu rc t - 2 -2 - I -1 3 2 0 -1 

(0e) 

"'-Instrument hei ghts: \dnd t 10 m; pre s sure, 3399 m HISL) ; ail' and de'.'poin t t emperature, 2 m. I.lnd and temperature 

s('ns o rs are l ocated approximately 15 m soulh .... ·es L o f t.hc rod ) n building on a to .... 'cr. Pressure sens ors are loca t ed ,n the observatory blli Iding. 

ttlaximuIn and minimum values '" hourly averages 

3.10.4 Samoa 

Since February 1977 both the anemometer and thermometer have been located 

on the sampling tower atop Lauagae Ridge. The anemometer is positioned on t op 

of the tower at a height of 14 m, and the thermometer for mea s ur ing air temperature at a height of 4 m above ground. The dewpoint temperature is meas ured 

from air sampl es drawn from the sampling stack. The wind distribution for t he 

first 4 years of this period is displayed in 16 cl asses of wind direction and 

three classes of speed (fig. 26). The southwesterly trade winds dominate the 

airflow at Cape Matatula, occurring 68% of the time in 1981. This compares 

with 73% for direc tions east through south for the first 4 years of t his 

period. For 1981 winds f rom the northwest quadrant (west through north) 

occurred 17% of the time. This is the s ame as that observed for the preceding 4 years. 

Sea sonal variations of all other meteorological variables are sma ll 

(table 24) in comparison with the other GMCC stations. Only slightly higher 

winds and cooler temperatures occur in the winter than i n su~ner. The annual 

average pressure, tempera ture, and resultant wind spee d for 1981 were 

1000.2 mb, 27.0 0 C, and 4.6 m s- l, respectively. Thes e va lue s comp are with 

1000 . 3 mb, 27.3°C, and 4.6 m s-l, res pec tively, for the previous 4 years. 

62 
SAMOA 

61 

w 

liND SPIZO (W/ S) 

__ .$1..,<5 

IIl:i:33S' . '<IO 

U~IO 

N 

s 'lIND ntflQ. 

, 

E 

SA MOA 

n-BO 

IV 

li ND SPEED (W/ s) 

__ 51" < 5 

m:m:I S , ., " 10 

Dwsllo 

N 

s liND PRIX!. , 

E 

Figure 26.--Wind rose for SMO for 1981, left, and 1977-1980, right. See 

legend for fig. 24. 

Table 24.-- 1981 SMO monthly climate summary* 

J.n feb N" Ap' N.y J,n J,I A'g Sep 0« Nov Oec 

Prevai ling wind SE SE SE SE SE SE ESE ESE ESE SSE SSE SSE 

di reel ion 

Average wind 2.9 3.3 2.7 3.4 5.3 4.7 5.6 4.2 4.3 4.4 3.0 3.6 

speed (m , ' ) 

Maximum wind II 13 16 10 12 12 II 10 II 12 10 II 

speedt (m s - 1) 

Direction of max. 145 320 150 325 140 135 120 60 120 160 155 355 

windt (deg. 

Average stalion 998 996.5 998.2 1000 .2 IODI. 6 1001.9 1002.2 1002.4 1002.3 1001.2 999.8 998.4 

pressure (mb) 

Maximum pressuret lOa) 1002 1004 1006 1006 100] 1006 1007 1007 1006 1005 1005 

(mb) 

Minimum pressuret 994 988 980 995 996 997 998 998 998 995 996 992 

(mb) 

Average air 28.7 27.5 27 .2 27.0 27.0 26.5 25.9 26.3 26.8 26.4 27. 1 27.1 

temperature (OC) 

Maximum tempe raturet 32 J3 31 31 31 31 31 31 31 31 30 30 

(0e) 

~linimum temperaturet 25 23 23 23 24 24 22 23 23 23 24 23 

(0C) 

''I nst rument heights: wi nd, 14 Ill; pressu re, 30 m (HSJ.); a i rand dewpoint temperature, 7 m. Wind and temperature 

senso rs "e located atop Lauagae Ridge, a distance 110 m northeast of t he stati on. Pressu re sensors are locaLed io 

th, s ta li on. 

tMaximum and mi nimum values are hourly ave rages. 

63 
3.10.5 South Pole 

The extent, depth, and duration of t he Antar c tic winter i s clea rly depicted by the very cold average monthly temperatures from April t hrough September at SPO. Iin im um t emperatures observed during these month s are consist ently below -70 °C (-94°F) . See table 25 for 1981 res ults . The very persistent surface wind from a grid northeas te r ly direction i s another domi nant 

climatologica l feature of the pole station . This is an i nversi on wind most of 

the year, f l owing down the Antarctic ice dome. The speed is typically about 

6 m s-'. The station is located on the Amundsen-Scott plateau, at an e l evation of 2.B4 km . The plateau exhibits little topographic relief within a 

100-km radius of the station, and i s near the western edge of the main ridge 

of eastern Antarctica. The highest point (elev. 4 km) on the plateau is about 

900 km east-northeast of the geographi cal South Pole. 

Figure 27 displays, in polar coordinates, the dis tribution of the wind as 

a function of speed and direc tion. In previous years the mo st prevalent wind 

direc tion ha s been east-northeasterly. The mo st prevalent direc tion i n 19B1 

was north-northeasterly . This i s due in large part to a marked increase in 

the percentage of stronger wi nd s (>10 m s-') that are predominantly f rom the 

north . Du r ing the previous 4 years, wind s peeds >10 m s-' have occurred 2% of 

the time. In 19B1 wind speeds >10 m s-' occurre d- 7.9% of the time. Calm conditions (wind speeds <0 . 5 m s-') occurred 0.2% of the time. 

The full extent of the austral winter on the Antarctic plateau i s s hown 

in the e ight monthly average air temperatures that are be low the annual average (-48.6°C); see table 25. The maximum hou r l y average temperature in 19B1 

was -1B.4°C (DOY 364) and the minimum temp erature wa s -7 5 . 6°C (DOY 256). The 

air temperature was mea s ured with a platinum resistance thermome ter (no. 954 

PL-C, Stow Laboratory, Hud son , ~Ia ss .) in a naturally ventil ated radia tion 

shie ld (no. 43103A, R. M. Young, Traverse City, Mich .) at a height of 2 m. 

SOUTH POLE 

8( 

w 

'lIND SPEID (W/ ll) 

-~" ~ 

c:iZZll SSU < IO 

0 11 3 a 10 

N 

• 

S 

E 

~ 

~ 

.. rlSD ntEQ 

, 

SOUTH POLE 

77-80 

IV 

r lSD SPtED (W( S) 

~' ~ 

c::::! ~ , I S " 10 

o _ SilO 

N 

,, ~ 

" 

S 

E 

• 

~ 

~ 

.. 'II so ntEQ 

.. 

Figure 27.- -Wind rose for SPO f or 1981, left, and 1977-19BO, right . See 

legend for fig. 24 . 

I 
Prevai li ng wi nd 

direc t ion 

Average wind 

speed (m 5- 1) 

aximum ""ind 

speedt (m s -I) 

Direction of max . 

wi nd t (deg . ) 

Average s t a t ion 

pressu re (Inb ) 

Maximum pressure t 

(mb) 

Min imum pressuret 

(rob) 

Ave rage a ir 

t emperature ( 0C) 

Table 25. --1981 SPO monthly climate summaryi, 

reb Ap r ay Jon Jol Aos Sep Oc t Nov 

N NNE ENE E N NNE N ENE NnE NE NNE NE 

555.86.26.57.17.5 8836.0 5.15.24.7 

I I 11 13 11 14 13 14 16 14 12 II 9 

I S 10 11 0 11 295 10345 10 20 15 25 30 

684 . 68 1.2 68 45675.7677.4674 .1 678.9681 .1 669B 672 .2673. 9 6783 

694 694 697 704 688 692 693 699 685 692 684 688 

669 674 672 650 666 658 665 663 660 654 660 668 

- 26.5 - 39.4 - 533 -59 . 5 - 545 - 58.8 -562 - 54.6 - 6 1.4 -54 . 1 - 39.5 - 25.8 

Maximum ternpera luret - 2 1 

(0C) 

- 30 - 3& - 37 - 32 - 45 - 40 - 42 -46 -41 - 27 - 18 

li ni mll m t empcra luret -)8 

(Oe) 

-48 - 66 - 73 - 71 - 74 -70 - 67 - 76 - 67 - 52 - 34 

';' I nstrument he i gh t s : I.dnd , 10 m; pr ess ure , 2850 m (MSL); ai r temperatu re , 2 m. The anemometer a nd t he rmometer are 

located 0" it mas t 30 m grid no rth o f t he Clean Ai r Faciilty. Pressure measu rements are mad£' i nsi de Lhf' faciliLY . 

Hlaximum and mi nimum va lues are hourl y ave rage s. 

3.11 Precipitation Chemistry 

Routine and special measurements of precipitation chemistry continued at 

both GMCC bas eline sites (MLO and S~10) and at regional sites . The routine 

measurements at GMCC sites are important in measuring the year-to-year variations of acid ity and in detecting possible long-term trends in precipitation 

chemistry. Recent studies have confirmed that the acidity level at other 

remote sites is similar to that found at GMCC baseline sites (pH 4.5-5.0) 

(Galloway et al ., 1982). Limited, special onsite chemical analyses, in 

addition to pH and conductivities, were performed at MLO and S~10. 

3.11.1 Baseline Measurements 

This is the first full year that ~ILO and SMO have participated in NADP. 

Data from these weekly co llections have been reported in the NADP quarterl y 

report. 

Onsite research measurements have continued, particularly at MLO and SMO. 

At these stations shorter term coll ections are made and samples are analyzed 

for the major ions on the ion chromatograph. The monthly average pH values 

for meas urement sites on the island of Hawaii are shown in fig. 28. Site descriptions have been documented in the GMCC Summary Report for 1977 (Peterson, 

1978) . 

65 
pH 

pH 

pH 

60 

55 

" 

' .5 

55 

5.0 

' .5 

' .0 

5.5 

5.0 

' .5 

Kumukahi 

Komenana Agricultural Complex 

/ -----'" 

/',~ ... - ' , " r-~~,-~-. 

" '... ... 1"'- J ... , I 

/ , 

, 

, 

\ .......... 

' .0 L-L_.1-___'_--'--_L_---'.~...L-L---"-~-L---'_,__--' 

Jan Feb MOl! Apr May Jun Jul Aug Sep OCI Nov Oec "a, 

3 .1 1 .2 Regional Measurements 

Figure 

va lues 

island 

28 .--The monthly average 

fo r measurement sites on 

of Hawaii . 

pH 

the 

The 10 WHO regional sites are also a part of NADP. A s ummary of their 

annua l average pH and ion concentrations is given in table 26. 

3. 11 .3 Washington, D.C., Network 

The pH data from six sites in the Was hington, D.C., area are s hown in 

fig. 29. 

66 
Table 26.--Average ion conce ntration and pH values a t WI'IO 

regional s ites from January 1981 to Decemb er 1981 

WI'IO 

regional sites 

Alamosa, Colo. 

Bishop, Calif . 

Caribou, Haine 

Huron, S. D. 

~Ieridian, Ii ss. 

Pendleton, Ore. 

Princeton , N.J.* 

Raleigh, N.C. 

Salem, Ill. 

Victoria, Tex. 

pH 

5 . 05 

5.87 

4.51 

5 . 69 

4.75 

5.64 

4.38 

4.52 

4.33 

5.01 

so. 

2 .05 

1. 25 

2 . 20 

3 . 17 

2 . 97 

0.45 

4 . 43 

4 . 70 

4.76 

1. 75 

1. 86 

0 .53 

1. 79 

1. 73 

1. 56 

0.96 

2 .15 

2.76 

2 . 32 

0.95 

"'S ince moved to Washington's Crossing , N. J . 

... n nu~1 

"vu~~~ Itt 

--82---

H' 

220 

2eo 

100 

16 ~ 1<0 ::--;: 

120 

100 

00 -

GO 

4 0-

20-

o I I I 

1075 

90---;1<--88--,1.-- 72-- '--65 _--;l)i.,.., --47 -- >---42 

, 

107G 1077 1970 1070 1000 1001 

Cl 

0.79 

0.8 1 

0.23 

0.76 

0.96 

0.30 

0 .50 

0.84 

0.46 

0.58 

pH 

3.7 

3.8 

3.9 

4.0 

4.1 

4.2 

4.3 

4.4 

4.5 

Figure 29. --Weighted monthly average H+ concentration (~mol Q- l x 106 ) 

and pH for t he Washington, D.C., network from 1975 through 1981. The 

" eighted annua l average H+ concentr ation is also given by the numbers at 

the top of the figure. 

67 
3.12 Data Management 

3 . 12. 1 I CDAS 

Each GHCC observatory records continuous data on magnetic tape using a 

minicomputer system called ICDAS . The A&D~l group within G~ CC oversees this 

system, which has been fully operational for more than 5 years. The overall 

performance of ICDAS in 198 1 was the best since its installation. The average 

downtime for the fo ur stations was about 3% or only 11 days out of the year. 

The performance statistics for the indivi.dual stations are as follows: SPO, 

98 . 3%; SMO, 97 .2%; LO, 93.1%; and BRW, 98.6%. 

The main reasons for ICDAS downtime were power problems at HLO and S~lO, a 

faulty multiplexer at BRW, and magnetic tape drive maintenance at MLO and SPO. 

In the middle of July an uninterruptable power supply installed at SMO solved 

most of the power problems there. This power supply was modified to run under 

i nternal oscillator freque ncy control rather than line frequency control. 

Noise levels within ICDAS were quite low by the end of 1981. This is 

attributed to the "quiet" linear power supp lies now in all the NOVA's and the 

fact that most ground loops and loo se connections have been found and removed. 

3.12.2 Reduction Facility 

Initial processing of station data tapes takes place in the reduction 

faci lity in Boulder. In 1981 A&DM renovated the reduction facility by upgrading both its hardware and software. The new hardware consists of a faster 

minicomputer (NOVA 4), a Winchester dis k drive, and a hardware multiply-divide 

board for faster computations. The programs that check and copy the station 

tapes were converted from BASIC to FORTRAN, giving a significant run-time 

savings. Because of the larger disk drive we are now able to operate under 

Data General's RDOS, which is more powerful than the previous operating 

system . 

A DECtape II (TU-58) cassette drive identical to those in the microprocessor-based data systems (s ee sec. 3. 12.3) was installed in the reduction 

facility. The software needed to link the cassettes to the NOVA was written 

so that data recorded on cassettes can be processed in the reduction facility. 

In addition to standard tape processing, the A&D~l group continues to 

support special projects, with the use of the reduction facility. For ex -

ample, a procedure was developed to decode and unpack the data tapes from the 

aerosol spectrometer. These data tapes will be routinely translated to a form 

readily useable on the CDC 750 computer. 

Finally, the A&DM group has upgraded the documentation for the reduction 

facility. The convenient central location of these manuals and instructions 

will make training for newcomers and students an easier task. 

3 . 12 . 3 II CM1S 

In the fall of 1978 members of the A&DN staff began design of a gas flow 

controller using microprocessors for the CO 2 program. The controller was completed early in 1979 and has been in operation since (Harris et al., 1980). 

68 
The success of this effort led to the procurement of a mi croprocessor development laboratory and the subsequent development of a controller for CO 2 gradient meas urement at lLO. Since the construction of these first controllers, 

t he Z80 mi crocomputer has been adapted as standard along with the STD-Z80 bus. 

A sta ndard bus allows simple plug-in access of s uch items as clocks, memory, 

analog-to-digital converters, input-output ports, and other standard f unction 

boa rd s . This collec tion of hardware and operational software ha s been named 

IICANS . Current plans are to begin r e placing ICDAS, project by project, early 

in 1984. 

IICM1S consists of the following: CPU, programmable memory, batterypowered memory, clock and serial input-output port for access to the front 

panel, and cartridge tape drive . The preformatted DECtape II ha s been selected as a recording med i um. It offers maximum reliability and a simplified 

mechanical design. The front panel is modular in design, providing a standard 

10-character keyboard and 8 special-function switches. The ana l og-to-digital 

converter is available with a programmable gain option . The entire unit requires only 7 in of a standard equipment rack. The software will be programmed into PRml so the system will restart automatically after a power 

failure. Variables produced by the system will be stored in memory that is 

backed up by battery. The clock i s also battery powered and will maintain the 

time for 5 days without recharging. The batteries in the memory and the clock 

will require changing every 24 months or so . A function switch will be 

assigned to the three primary pe r ipherals (clock, AID converter, and cartridge 

tape) to allow access and control. Four function switches will be reserved 

for the use of individual programs. 

3.12.4 Archiving 

Table 27 lists the G~lCC data archived at the WDC-A in Asheville, N.C. 

Except for tapes written in Res ea rch-Cooperator format, each archive tape 

contains a preamble in card-image format that describes the data. Copies of 

the tapes c an be obtained from User Services Branch, 05421, National Climatic 

Center, Asheville, NC 28801 (FTS 672-0682 or (704) 258-2850, ext. 682). GNCC 

archive tapes are located in tape dec k no. 9708. 

In addition to these data tapes, GMCC has archived all available CO 2 

flask data from stations in the CO 2 flask network , through 1978, in a yearly 

WDC-A publication, "Global ~lonitoring of the Environment for Selected Atmosphe ri c Constituents. It 

69 
Table 27.--Inventory of GMCC data tapes at World Data Center-A 

No. Tape Date of Para meter Station Period 

name issue of data 

MLONFl 12/ 09/71 Volumetric light MLO 1914-1916 

scatter ing 

2 GPOLOI 1/16/78 Condensation nu c leus BRW 1915 -1 916 

concent ration MLO 1915-1 916 

SPO 1915 -1 916 

3 A18016 3/11 /68 Solar irradiance tlLO 1977 

4 A18083 3/24/7B Solar irradiance SMO 1977 

5 A1B100 3/10/7B Solar i["radiance BRW 1977 

6 A18 104 4/14/78 So lar irradiance MLO 1916 

1 A18 132 5/12/78 NIP radiation BRW, MLO, 1977 

SMO, SPO 

8 A18 139 5/19/78 Wind, pressure, BRW, MLO, 1977 

temperature, SMO, SPO 

humidity 

9 A18146 5/26/78 Solar irradiance SMO 1916 

10 A18160 6/09/78 Solar irradia nce SPO 19 16-1977 

11 A18230 8/18/78 Solar irradiance BRW 1916 

12 A18272 9/19/78 Solar irradiance BRW, MLO 1918, first 

half 

13 A18219 10/06/78 Solar ir radiance SMO 1918, first 

half 

14 A19121 5/01/79 Solar irradiance SMO 1916 

(Research-Cooperator 

format) 

15 A19128 5/01/79 Solar irradiance SMO 1977 

(Research-Cooperator 

format) 

16 Al9208 1/21/79 Solar irradiance tlLO 19 78, second 

half 

11 Al92 22 8/ 10/79 Solar irradiance SMO 1978, second 

half 

18 A800 10 1/25/80 Carbon dioxide HLO 1914-1918 

19 A80011 1/25/80 Ca rbon dioxide SPO 1916 

20 A800 12 1/25/80 Carbon dioxide BRW 1913-1918 

21 A80036 2/05/80 Solar i rradiance BRW 191B, second 

half 

22 A80015 3/16/80 Solar irradiance SPO 191B 

23 AB 11 2B 6/10/B1 Solar irradiance MLO 1919 

24 AB 11 55 6/ 10 /B l So l ar irradiance StlO 1919 

(Researc h- Cooper~tor 

format) 

25 AB 1155 6/ 10/81 So lar irradiance BRW 1919 

(Research-Cooperator 

format) 

26 A8 11 10 1/ 09/81 Solar irradiance SPO 1919 

(Resea rch-Cooperator 

format) 

21 AB1190 8/12/Bl So l ar irradiance BRW 19BO 

(Resea rch-Cooperator 

format) 

28 AB 11 93 8/12/B l Solar irradiance MLO 19BO 

(Research-Cooperator 

format) 

29 A81201 8/12/B l Solar irradiance StlO 1980 

(Research-Cooperator 

format) 

30 AB 1211 B/12/Bl Solar irradiance SPO 19BO 

(Research-Cooperator 

format) 

70 
3.13 Atmospheric Trajectories 

3.13.1 Introduction 

In 1976 an atmospheric trajectory program developed by J . Heffter and A. 

Taylor (GMCC Summary Report f or 1976, Hanson, 1977, p. 60) became opera tional . 

This program runs on the NHC compu ter in Suitland, fld . , and produces printed 

plots. In 1981 J . Harris of GMCC modified the program to run on the NOAA 

CDC 750 compu te r in Boulder so that the GHCC group would have easier access to 

traj ectories. At the same time the program and the output plots were tailored 

to s uit the needs of the scientists in Boulder . Although the accuracy of the 

t ra j ectories is limited by the quality of the input data and t he s implicity of 

the model, these tra j ectories, wh en used in conjunction with other meteoro -

logical parameters, ca n be an effec tive research tool to indicate large-scale 

airflow patterns. 

The new version of the trajectory program is called GAMBIT for gridded 

atmospheric multilevel backward isobaric trajectories. As the name implies, 

the trajectories produced are comput ed from analyzed winds along consta nt 

pressure surfaces. Trajectories at two or three standard leve ls are computed, 

then displayed on a map. Although earlier versions of the program computed 

trajectories by averag ing the winds through a se l ected layer , multiple trajectories at s tandard pressure l evels were fo und to be preferable. In fact, 

the average-layer technique could yield trajectories that are not realistic . 

At MLO for examp le , when northeast trades dominate the lower levels and 

westerl y winds prevail in the up per levels, there is no meaningful average 

between these two distinct wind regimes. 

3 .1 3 . 2 The GA1'lBIT Program 

NCAR in Boulder now furnis hes the meteorological input data on magnetic 

tapes (Jenne, 1975). These data, originating from NNC, are analyzed wi nds at 

10 sta ndard pressure s urfaces: 1000, 850, 700, 500, 400, 300, 250, 200, 150, 

a nd 100 mb. As of the end of 1981, 5 years of data (1976-1980) were obtained 

from NCAR with two data records (0000 and 1200 Z) for each day. The raw 

gridded data are packed in a de nse binary format (NNC, 1979). As standard 

procedure, only the first four levels (1000, 850, 700, and 500 mb) are unpacked . If upper levels are needed they are handled as a special case. As 

the data are unpacked, the order of the records is checked a nd one or two 

missing records are filled by interpolation. Interpolation has been necessary for only a few percent of the data. A gap of three or mor e records 

(>24 hours) constitutes a break in the data. Trajectories must terminate 

where t here is a break in the data, but for the 5-yr period only two breaks 

occurred: 2 days starting 7 August 1980, and the last l~ days of 1980. 

The wi nd data are available in the form of U and V components on a 

65 x 65 grid called the mlC grid for the Northern Hemisphere (fig . 30) . The 

grid is a square matrix overlayin'g a polar stereographic projection of the 

hemisphere with a resolution of about 200 km per grid unit at the equator to 

about 400 km per grid unit at the pole . The wind data are computed by NNC's 

Optimum Interpolation Analysis Hodel (personal communication, R. Jenne, NCAR, 

1981). The model starts with a forecast for the time period and then modifies 

this according t o meteorological observations reported from around the globe. 

As might be expected, obs erva tions are sparsest near the Arctic and densest 

71 
----- :( I _______ I 

~~ I'" 

/I t I =i(\,/'h 

L 1 I i I I( IW 

/~ I :9( :'; ) 

( I I\r-, 1.1' \i! 

J ~~ ~ t--., . ~ " 

: '1' , ~, " ) 

\ j '" '\ 

~ -.J\ ~ f 

'\: 7 /"'\ l)' 

'''-... i li 'hP % '-i'--- ~ L y 

l'\ 

\ 

. 

/ 

v 

I 

\ 

II 

Figure 30. --The 65 x 65 NNC grid for 

the Northern Hemisphere. Grid point 

(0,0) is i n the lower left corner. 

Eve ry fifth grid line i s shown. 

over well-populated landma sses. Where the mode l has f ewe r real observations 

to const rain it, the wind data it produces may be less reliable, so that trajectories in these areas s hould be cross-checked with other data source s. 

The ba sic computations that convert U, V wind components on the NNC grid 

to a trajectory segment are identical t o those in previous versions' of the 

trajectory program (Heffter and Taylor, 19 75). A 10-day trajectory consists 

of eighty 3-h trajectory segments placed end to end. To compute one 3-h segment, the endpoint of the last 3-h s egment is located with respect to the NNC 

grid; i.e . , (latitude, longitude) is conve rted to (x, y) . The wind is calculated at (x, y) using bilinear interpolation from the four grid points surrounding (x, y). The iterative scheme us e d to approxima t e the va lue s of U a nd 

V representative of the 3-h period is the modified Euler method. These values 

are ass umed consta nt for 3 hours to obtain the 3- h segment and the new 

endpoint. 

3 .13. 3 Plotting the Traje c tori es 

Three forms of the plotting program are now in use . The first type, 

shown in fig. 31, plots trajectories for one arrival time, 0000 or 1200 Z 

(shown here for 0000 Z), and three standard levels . The lowest level, in this 

case 85 0 mb, is marked L; the middl e leve l ( 700 mb) is 1'1; and the upper level 

(5 00 mb ) is U. A character, either the letter indicating l eve l or a number, 

appears eve ry 12 hours along the trajectory. The number gives the time in 

days for an air pa rcel to travel from that point to the origin . The second 

t yp e of plot (fig. 32) shows tra ject ories for t wo standard levels and two 

arrival times (0000 and 1200 Z) during the day. Aga in the identifying le tters 

alterna t e with numbers s howing number of da ys back. The legend at the top 

s hows that A and B arrive at 0000 Z, that C and D arrive at 1200 Z, and t hat 

levels 700 and 500 mb are plotted. Finally, the t hird type of plot (fig. 33) 

displays all trajectories for a se lected level over a given time pe riod . This 

output i s useful for climato logical and case studies where one is concerned 

with ge neral airflow patterns, not individual trajectories. Al though these 

three typ es of plots cover most needs, other types are possible. 

72 
Ml.O TRAJEXTORIES ARRI\'I I\G 79113 - 4 '23, 79 AT OZ 

k 6.'iO MB M 700 MS U 500 MB 

300N · 

100 S . 

160" \II" 180°\'1' 

Figure 31. --Sample plot of ~!LO trajectories for one arrival time and 

three isobaric surfaces. 

Wl.O TRAJfX.i'ORIES ARR I VING 79181 - 8/ 10/ 79 

A: f!l ,.. o. C: 127. ,.. o. aoz ,.. o. D. 127. 500 NB 

r? ~oN . 

10° N . 

10° S . 

, 

l200W 

Figure 32.--Sample plot of "LO trajectories for t wo arriva l times and 

two isobaric s ur f aces . 

73 
"1.0 700 .. 8 TRAJfrTORI CS ARRIVINC ?g(J84 1'0 7'9091 

I~'W 

Figure 33 .--Sample pl ot of MLO trajectories arriving over a period of 

8 days along one isobaric surface. 

The trajectory endpoints are computed and saved on magne t ic tape . Once 

on magnetic tape they may be plotted any number of times in any desired form. 

Next year archival of the e ntire set of trajectory endpoints for MLO a nd 

Bermuda (1976-1981) on magnetic tape is planned. Tra j ectories for other 

origins will be computed as the need arises. The GAMBIT program wi ll be 

modified in the f uture to accept the NNe 2 .50 gl obal analyzed winds so that 

not only traj ectories for S~ O and other points in the Southe rn Hemis phe r e can 

be computed, but a ls o data can be available to i nvestigate cross-equatorial 

flow. 

74 
4. SPECIAL PROJECTS 

4.1 Mod e ling the Atmospheric CO 2 Co ncentration 

On a gl oba l sca l e the change of CO 2 concentrati on during the year is 

caused by (1 ) combu stion of fossil fuels that can have a seasonal varia t ion, 

for example, due to space heating in northern latitudes; (2) biospheric uptake 

and output due to amount of biomass, which is a functio n of cha nging seasons , 

land/ocea n ratios, climate patterns, soil fertility, etc .; (3) oceanic upt a ke 

and output, which is a function of pre sence of ice, concentra t ion of CO 2 in 

water , water temperature, wind speed, biological ac tivity in the ocean, ocean 

circula tion, etc . ; and (4) atmospheric mixing, which transports excess CO 2 

produced at one location t o other locations throughout the atmosphere. 

Each of the above four ca uses of variation is considered in modeling atmospheric CO 2 concentrations . The fo ur ingredients of the model are l isted 

below. 

( 1) Atmospheric mixing. A two-dimensional atmospheric diffusion model 

(Machta, 19 74) has been adapted for use in CO 2 modeling. It has 26 vertical 

layers and 9 l a titude ba nd s. Mixing coefficients are derived from bomb debris 

data and other diffusion studies. 

(2) Oceani c uptake. As s hown in f i g . 34, two oceanic layers were added 

t o the Machta a tmospheric diffusion mode l. The first layer, the mixed layer, 

has variab l e depth while the depth of the second layer is held constant . The 

relation between concentration of CO 2 species in the ocean water and the partial pressu re of CO 2 now assumes a constant total alkalinity. The model calculates hydroge n ion activity, then computes the proportion of CO 2 t o total 

dissolved inorganic carbon by using equilibrium constants, which are a function of salinity and water temperature, for dissociation of CO 2 in water. 

The f lux from ocean water to the atmosphere is a part of the model that 

will vary pa rametri cal l y. At pres ent, the f lux is a function of differences 

of partial pressure of CO 2 in the air and in t he water multiplied by a function of wi nd friction velocity. Initial values of total dissolved inorganic 

carbon wi ll be varied in the model. Ice coverage will be added to ocea ni c 

ar eas as a fun c t ion of time as determined from sea ice records. 

(3) Biospheric CO 2 fluxes . Fluxes to and from the biosphere will be 

pa rame t e rs in the model and will be varied in numeri cal experiments . One 

exampl e of biospheric fluxes is shown in fig. 35. 

(4) Fluxes of CO2 from combustion of fo ssil fue l s . These have been 

tabulated by Rotty (1982) as a function of latitude as shown in fig. 36 and 

will be us ed to specify anth ropoge nic CO 2 contributions. 

By variation of unknown parameters, the model can be compared with co nce ntration data to obtain ranges ~f globa l oceanic fluxes and biospheric 

fluxes . Then by eva luating the data, planning sampling stra tegy , and estimating global oceanic and bi ospheric fluxes, adjustments can be made such that 

mod e l and sampled CO 2 concentrations agree within some range of uncertainty. 

75 
4 0 

39 

7 

3 5 

3 

3 

, 

, 

, 

, 

, 

3 

\ 

, 

7 

5 

3 

\ 

, 

7 

5 ~ 

3 ~'"'" 

\ 

, 

6 

5 

3 

\ 

0 

~ 

·0 . 51-

.\ 

Stratosphere 

-

,,,-l\.,e J\1;~ing I 

C;,\o(\ I ':':."'#," 

,...,........ ,_!.!",o~~e~~se ''''''''~ I '"'''' l::::", 

Troposphere 

t . t 

r-H+ , t t T 

m=,~ ~ 

, 

I I I \ I I I I 

90G N 70 . . 50 30 . 10 . 10 . 30 . . 50 70 . . 90 S 

Figure 34.--Schematic presentation 

of the two-dimensional atmosphericocean CO 2 diffusion model . The 

upper part of the figure (atmospheric diffusion) is after Machta 

(1974) , 

0; 

c. 

., 

~ 

E 

N 

0 

U 

lotitude 

Figure 35.--Biospheric fluxes 

(Tg mo- ' , 20° latitude band) as a 

function of latitude and time of 

year . 

'1000_ 

~. 

-. 

Lotitude 

J 

\ 

1 

Figure 36,-:Industrial CO 2 input per 

year (Tg yr 1), after Rotty (1982), 

4.2 Analysis of SPO's CO 2 Record for 1976-1980 

4,2,1 Introduction 

The South Pole, being extremely distant from sources and sinks of CO 2 and 

therefore relative ly free of sources of short-term CO 2 variability, is one of 

the most desirable sampling locations in the world . Its record of CO 2 concentration is a smooth history representative of a large part of the globe. 

However, its remote ne ss and extreme environmental conditions offer difficulties in obtaining data, The CO 2 concentration data record for 1976-1980 had 

three discontinuities of concentrations corresponding to changes of infrared 

sources in the continuous analyzer and in a change of reference gas from 

CO 2 -in-nitrogen to CO 2 -in-air. 

76 
While Noise 

, 100"", , do, .. " 

Period 

4.2.2 Variability of CO 2 at SPO 

" 

1" , 

~ 

j 

r 

] 

1 

1000. .. 

~ .;; 

c 

'" " 

~ 

u 

'" 0. 

rn 

Figure 37.--Spectrum of atmospheric 

CO 2 hourly mean variability. 

tlinute-to-minute variability of CO 2 was found to be practically nonexistent at SPO. All variability of a minute-or-less time scale was explained by 

instrumental noise. Variability of hourly means of CO 2 for 1976 (a · year when 

no discontinuties and little downtime occurred) is shown in fig. 37. Three 

conclusions were drawn from the 1976 data. 

(1) Variability on time sc~les smaller than 12 hours is white nois e. 

There is very little power for variations having time scales smaller than 

75 hours. 

(2) On the basis of a study of residuals for the fitted function, 

f(t) = a + bt + ct 2 + dt 3 + e sin (;~~) + f (

2Tlt) cos 365 

+ g sin (;~~) + h cos (;~~), 

where t = day of yea r, a -h are coefficients determined by the least-squares 

fit, and f(t) is t he predicted CO 2 concentration, no significant spectral 

peaks were left for a single year's fit. Thus it is felt that the above 

function can adequately describe the SPO CO 2 record for 1 year. 

(3) With the exception of instrumental failure or obvious contamination, 

no residual for a fit of 12-hourly values was larger than 0.1 ppm. 

77 
..... . " 

.' 

Figure 38 .--Selected SPO daily CO 2 

means. 

4.2. 3 Data Selection and Discontinuity Removal 

A data selection method followed from point (3) in sec. 4.2.2: 12-hourly 

mean CO 2 values were fitted linearly, and residuals larger than 0.1 ppm were 

removed. The discontinuities of the data were removed by an exponentially 

decaying correction, which assumes that the value for CO 2 was accurate before 

the infrared sources in the continuous analyzer were changed. 

4.2.4 Data Record 

The corrected record of atmospheric CO 2 concentration is shown in fig. 38 

for 1976-1980. The data are reported in the 1974 SIO mole [ca cLion He.le. An 

estimate of the annual mean CO 2 increase from these preliminary d~ta is 

1.4 ppm yr 1. This number is slightly larger than the 1. 3 ppm yr 1 value for 

the linear coefficient of increase reported by Keeling et al. (1976) for the 

period 1957-1971. The annual mean range after the linear increase is removed 

from the record is approximately 1.7 ppm. 

4.3 Atmospheric CO 2 Variations Measured in the North Pacific 

Region and the Southern Oscillation 

Recent research ha s shown that the rate' of change of CO 2 concentrations 

at SPO, Fanning Island, MLO, and Weather Station P (Papa) correlate with an 

index of the Southern Oscillation and the associated El Nino phenomenon 

(Bacastow et al., 1980). These authors further suggest that the relatively 

weak El Nino of 1975 as well as the fully developed El Nino of 1976 were 

linked to atmospheric CO 2 anomalies meas ured at these loca tions . To continue 

this line of research, CO 2 concentration data from the GMCC bas eline stations, 

BRW and MLO, and from Station P were analyzed . Although the data sets were 

different from those used by Bacastow et a l., the data were analyzed in a 

similar manner. The resulting inverted time derivatives of the CO 2 anomalies 

are s hown in fig. 39. 

Figure 39 shows a similarity in the structures of the CO 2 anomaly derivative curves, which supports the view that these stations are measuring 

hemispheric-scale CO 2 perturbations. The CO 2 anomaly in 1975 (the dip in the 

three curves ) decreases with increasing latitude . This featur e is evident in 

the BRW record, but its magnitude is quite small. In contrast, the 1976-1977 

78 
~~ ~ ~~ 1 

~ 0 0. 

- - 1 

w 

~ 2 

;;; 

> 1 

~ 0 

~ - 1 

! :: 

2 _20 . Barrow j l ~ _3L-:::c-'-=--'--=:c--'--=-'-=-"--:~'-:c,-J 

73 74 75 76 77 78 79 

Year 

Figure 39.--Inverted time derivatives of the CO 2 anomaly curves (in 

the manner of Bacastow et al . , 1980) 

at MLO, Weather Station P, and BRW. 

The CO 2 anomalies are the differences between observed monthly 

average CO 2 concentrations and the 

detrended long-term CO 2 record a t 

each location. Long-term growth 

rate factors of 1.0019 for BRWand 

Sta tion P and 1.00423 for MLO were 

used in these calculations. The 

apparent responses to the 1975 El 

Nino and the 1976-1977 anomaly are 

ind ica ted by arrows. 

CO2 anomaly is quite prominent, and its greatest amplitude is at Station P. Moreove r, the phase of the anomaly minimum at Station P slightly precedes that 

at the other two locations. This evidence suggests, but does not prove, that 

different forcing functions produced the two anomalies. 

Other researchers have s hown that the 1976 decreas e in the slope of the 

long- term atmospheric CO 2 concentration records from BRW, Station P, and MLO 

are significantly correlated with coincident SST DN in the North Pacific Ocea n 

(Hanson et al ., 1981; Schnell et al., 1981). At BRW, this decrease was of 

such magnitude that the annual average CO 2 concentration in 1976 was 0.1 ppm 

l ower than i n 1975 ( Peterson et al., 1982). The correlation patterns between 

the CO 2 DN and SST DN for MLO are shown in fig. 40 . In this figure, the 

positive correlation patterns (no lags) in the North Pacific in 1976 are 

worthy of note . 

In an ex tension of the above analysis, corre lations between the Southern 

Oscillation and SST DN were calculated, with the results shown in fig . 41. 

The s haded areas indicate zones of positive correlation of +0.6 and larger. 

By comparing figs. 40 and 41, a marked similarity in the areas of high positive corre lation may be observed for 1974 and 1976. Point correlations of 

+0.9 occur in similar locations in the same years in both series . 

These correlations between the Southern Oscillation and both the North 

Pacific CO 2 DN and the North Pacific SST DN suggest that each is either 

responding to some other undocumented forcing or that one influences the 

o thers . It is known t hat the Southern Oscillation is po sitively coupl ed to 

the North Pacifi c pressure-wind system (i.e., weather) and that t hese teleconnections affec t broad areas of the North Pacifi c (White and Walter, 1973). If 

the Southern Oscillation is directly influencing annual CO 2 concentrations in 

the North Pacific, the mechanism by which it doe s so is uncl ea r. 

One possible mechanism is abnormal seasonal SST. The theoretical atmospheric CO 2 response to ocean coo ling i s a decrease in the slope of the longterm CO 2 trend. Conversely , an abnormal ocean warming increases the slope of 

79 
. , 

-, , -. 

1110' 160' 

('t ' • 

:>. 1 

.~ . 

-.? 1<0' '20' 

/J 

-~ ~(; :' e:~l l\ i · [) . 1 • • 

~ . . ,6 ·.'::;; . . 101 - ••• / . o • ~ •• 

.~ 1974 

'~.'. 

W 1975 

<11 1977 

'2O'E ><0' IW' nlo' 160' ,,:>' 'Xl' 100" •• 

.il' ,978 

12O'[ ,~ 160' 110' 160' ''0' 1/'0' 100"'"' 

tOl'lglllKle 

Figure 40.--Correlations of NLO CO 2 

DN with SST DN, year by year for the 

period 1974-1978. Shading indicates 

correlations 0.6. 

~. 

"'. 1976 

,;c' .. , 

~ 

. . .. : . . . l .L.; 

~' ... 

~.~

~ ~ . 

~ 

t'··

.

··· 

~ . . . • 'l· ~~m/(. 

'0' 1971 

'1'(:'[ '«1' ,ro' 1110' 160' "'0' 'n' 100· ... 

·I ~,:·­ .~, , ... ~ . . '10'[ "0' ,~. ,to- 160' '0(1' 'l'O' .:;0 ..... 

Figure 41.--Co rrelat ions of the 

Southern Oscillation I ndex wi th SST 

DN, year by year for the peri od 1974 -

1978. Shading indi ca t es correlations 0.6. 

t he tre nd. Both the CO 2 anomaly derivative studies and the DN studies for CO 2 

and SST presented above support the s uggestion tha t abnormal seasonal SST's 

affect atmospheric CO 2 concentrations in the Pacific basin. 

Further, if one accepts that the Southern Osc illation is related to 

seasona l North Pac i fic wea the r, and that these wea ther patterns influence SST, 

the correla tion patterns discussed above may be explained. Other exp l anations 

f o r the CO 2 DN' s , s uch a s changes in hemispheric-scale flow or changes in 

global mixing of fossil fuel CO 2 , are being studied. 

80 
4.4 CO 2 Flux Estimation at BRW 

A new CO2 i nl e t l i ne was mounte d 0 . 3 m above t he t undr a a t BRW in J une 

198 1. Samp l es of 5-min dura tion a r e passed th ro ugh the continuous CO 2 analyzer once an hou r on t he ha l f -hour ; the remaining time of the a na l yzer is 

devoted to amb ient air sampl ing from t he line moun t ed 10-m above the tundra , 

and to calib rati on. In conjunc t ion with t he regular CO 2 conce nt r a tions measur ed at 10 m, t he da t a from the groun d l i ne a llow f or rough es t i ma t es of CO 2 

flux into and out of the tund ra. This in turn provides a mea ns for determi ning the role of Arc t ic t und ra vege t ation i n t he global CO 2 cyc l e . 

CO 2 mean concentrations measured at t he t wo l eve l s (pl ot ted in LST and i n 

t he 1974 mol e fraction sca l e ) are s hown i n fig . 42 for a l-wk pe riod i n August 

1981. I n t his figure, a high- amp litude diu r nal cyc l e is evident in the gr ound 

line data, and a diur na l cyc l e of l esser ampl itude is i n the uppe r-li ne data . 

A general trend of decreasing average CO 2 concentra tion is p resent in t he 

upper-li ne data; th is reflect s t he an nual s ummer CO 2 drawdown obse r ved a t BRW . 

The di f fe r e nce in CO2 concentra t ion be t wee n the uppe r and lowe r lines i s 

s hown i n fig. 43 for the same period as i n fig. 42. CO 2 va lues be l ow the zero 

line represent pe riods when smal l er CO 2 concentrations were meas ured near 

ground level, and va lues above t he zero l ine represent periods whe n ground 

l eve l CO 2 concentrations we r e higher . For this wee k in August the r e we r e mor e 

hours whe n the CO 2 concen tra t ion was lower nearer the ground tha n the oppos ite . 

CO 2 fluxes into and out of t he tundra were estima t ed using the CO 2 concentration differences in fig. 43 along with measu r ed wind speeds and deri ved 

7 

~ 

! 

- Air line 1 (10 m) 

Air line 2 (0.3 m) 

,-----,----,----,----,----,----, 

" 10 II 12 13 

AUGUST 1981 

Figure 42. - - Hou r l y mean CO 2 concen -

trations meas ured a t two l eve l s at 

BRW. The inlet t o the lower l i ne i s 

0 . 3 m above the t undr a vege t ation; 

t he height of the vegetation is an 

average 0 . 2 m. The CO2 concentrat ions meas ured a t the 10-10 height 

constitute the a tmosphe r ic CO 2 rec -

ord for BRW. Time is gi ven i n LST. 

81 

M 

~ 

N 

~ 

? 0 ~ 

0. :=:0 ~ 8 9 

<l 7 

~ , 

N 

, 

~ , 

M , 7 +----,--~--,-+ -r----.- '-._-" ag iO U 12 13 

AUG UST 1981 

Figure 43.--C02 concentrati on measu red at 0 .3 10 minus t ha t at 10 m. 

Negative va lues r ep resent periods of 

CO 2 upta ke by t he vege t a tion , and 

positive va l ues represent CO 2 egress 

fr om the vegeta ti on . Time i s g iven 

in LST. 
mixing coefficients. These estimations a<e necessarily <ough because ( 1) CO 2 

concentration data were not obtained at exactly the same time for t he two 

heights sampled; (2) wind data were obtained at on l y one height ( 10 m); a nd 

(3) tempe<ature stratification data were not avai l able. Nonethe less, estimates of CO 2 vertical fluxe s were calculated using the method of Se hme l a nd 

Hodgson (1976) . The vertical CO 2 flux was expressed as 

The val ues of Xhi and 

vertical heights Zhi 

Brownian diffusivity, 

I Zh' 

Xl )p 1 1 dz/(E 

a a Z 

+ D) . 

10 

Xlo are mass mixi ng ra tias of CO 2 a t the high and 

and Zlo; E and D are particle eddy diffusivity a nd 

respectively; ll". is wind friction velocity ; and Pa 

low 

is 

the density of the air. The integral in the denominator was evaluated to be 8 

for a slightly unstable condition o f Monin -Obukhov length L = -5 ,000 cm . With 

assumed values of aerodynamic roughness height Zo = 0. 5 cm, and Monin-Obukov 

length L = -5,000 cm, the relationship 

u~, = 0.0534 ulOm 

was obtained, where u IOm is the hourly mean wind speed at the 10-m height . 

Thus the approximation 

was made, whe re lIIO dimensionless volum~ is measured in meters per second, and C10 and Chi are 

mixing ratios. 

Hourly CO 2 f luxes for t he months of J uly, Augus t, and September are shown 

in fig. 44, where negative values r epresent CO 2 uptake by vege tation and po sitive values represent egress of CO 2 from the vege t a tion layer. Notice that 

the amplitude of the daily CO 2 fl ux cycle increases through the l ast week of 

July and then becomes relatively steady for a month. In the last wee k of 

August, the amplitudes of the cycles are decreasing until they approach noise 

levels in late September. The high-amplitude ' cycles correspond to the pea k in 

the growing season of vegetation on t he tundra. 

The fluxes of CO 2 measured a t BRW ranged from O_to 1 x 10- 8 g cm- 2 s- 1, 

with a few excursions in excess of 2 x 10- 8 g cm- 2 s 1 during the peak growing 

season. The se estimates are in qualitative agreement with those obtained by 

Co¥ne and_Kel!ey (1975) who measured sununertime CO 2 fluxes from 0 to 1. 6 x 

10 8 g em 2 slover tundra near Pt. Barrow. CO 2 flux measurements over 

growing vegetation in lower latitudes suggest that the fluxes generally do not 

exceed 3 x 10- 8 g cm- 2 s-1 (Verma and Rosenberg, 1976). 

The integral of the CO 2 flux a t the 0 . 3-m height was calculate d for the 

period from snow melt (20 June 198 1) until the ground line became buried in 

snow (23 October 1981). The results are shown i n fig. 45 in conjunction with 

atmospheric CO 2 concentrations measured at the 10-m height . From this figure 

observe that atmospheric CO 2 is being deposited in the vegetation from earl y 

J uly to mid-August, at which point the vegetation becomes a net contributor of 

82 
E 

u 

SEP 

1981 

Figure 44. --Hourly CO 2 flux values 

for the growing season at BRW. Negative values represent periods of CO 2 

up take by t he vegetation, a nd positive values represent CO 2 egress 

from the vegetation. Time is given 

in LST. 

Sroo. !Mit ,,-

\. 

EO 

!~ ,,/ 

. ..: .... ~ 

.f' ,E u g~ ! 

3 ' ,' . ~~ 

~ ~~ 

R ~8 

~~~~77.~~~~~~ JAN FEB WAR APR WAY JUN JUL AUG SEP OCT NOV DOC f MONTH 1961 

Figure 45.--Hourly mean CO 2 concentrations at BRI, (smooth line, 10 m) 

and the integral of the net hourly 

CO 2 fluxes illustrated in fig. 44 

(broken line, 0.3 m). The spring 

drawdown of the CO 2 cycle is seen to 

occur some months prior to snowmelt 

at BRW. In the fall, the rise in 

the annual CO 2 cycle is later than, 

a nd continues well past, the time 

the tundra is frozen and covered 

with snow. 

CO 2 to the atmosphere. The fact that the integral does not return to 0 has a 

number of possible explanations: (I) the mixing coefficients used were incorrect and/or were not constant over a day or over the growing season (likely); 

(2) decomposition of local vegetation was not complete at the time of snowcover (possible) ; or (3) a net annual positive fixation of CO 2 by the tundra 

occurred (unli kely). 

The question of whether CO 2 release through decomposition of the local 

vegetation was in balance with CO 2 fixation earlier in the growing season is 

difficult to answer without accurate determination of the mixing coefficients . 

Uncertainty in t he mixing coefficients will be considerably reduced in the 

1982 CO 2 data flux calculations because data will be available from a second 

temperature sensor and a new anemometer that have been installed at the height 

of t he ground CO 2 line. Research on the CO 2 budget for Arctic flora (Coyne 

and Kelley, 1974) has shown that at soil temperatures warmer than -7°C there 

is subnivean release of CO 2 from the tundra. ~!uch of this CO 2 is apparently 

released to the atmosphere when the snow melts the following spring . Assuming 

t hat this occurred i n the fall and winter of 1981 may explain the shortfall of 

released CO 2 evidenced in fig . 45. Analyses of the CO 2 fluxes released during 

the thaw of 1982 should provide further information on the matter. 

The possibility that there is a net annual excess fixation of CO 2 by the 

Arctic tundra is remote because then the biomass would double in about 

5 years, on the basis of the values presented in fig . 45 . This has not been 

observed. Even if there were a net positive CO 2 fixation in any year, excess 

decomposition in subsequent years could very well balance the equation or produce a deficiency, depending on the moisture and temperature pattern of that 

particular season. 

83 
In fig. 45, the obse rve d BRW CO 2 cyc l e is seen to beg in its annual spring 

decrea s e in earl y April , a bout 2 months prior to s now melt. In the fall, the 

annua l cycle is still rising 2.5 months a ft er ground freeze and s now cover. 

It may be stated with some assura nce that vegetation on the tundra i s not cons uming CO 2 in April or May . In J uly, the a nnual CO2 drawdown becomes relatively s t e ep, which ma y reflect the consumption of CO 2 by lo cal vegetation. 

In the f a ll, t he annual cycle is still rising months after the t i me expected 

for high-latitude s now cover to considerably redu ce or terminate plant 

decomp osi tion and so il-to-atmosphere transfer of CO2 , 

The a nnual CO 2 cycle at BRW does exhibit the expected timing of growth 

and decay of vegetation in a soo - 60 oN latitude band. Coinci dentally this same 

latitude band encompa sses the zone of the l argest nonequatorial net primary 

productivity of CO 2 on Earth (Box, 1978). Also, i n terms of gross a nd net 

p r imary productivity, a nd seasona l primary productivity of CO 2 rate, Schnell 

and Harris (1 98 1) have s hown that CO 2 fixation and release by tund ra vegeta -

tion do not adequate l y account for the amplitud e of the CO 2 cyc l e observ.ed a t 

latitudes in the region of 70oN. 

In s ummary , it appears that both t he timing and amplitude of the BRW CO 2 

cycle can be expl ained if it is ass ume d that t he cycle refle cts the growth and 

decay of vegetation at lower latitudes. 

4.5 Air Mass Types Associated With Extremes in 

Winter CO 2 Concentration at BRW 

The relation between wi nter CO 2 concentra t ion at BRW and air mass type 

was s tudied to supplement a n earlier study of CO 2 variabilit y ba sed primarily 

on trajectories (Peterson et al ., 1980). Fifteen cases of the largest 

deviations (up to 3 ppm ) of CO 2 concentration from ave ra ge , for a 3-mo period, 

were conside red. Info rmation about the hori zo nta l and vertical struc ture of 

the a tmosphere was combined to characterize air masses associated with these 

CO 2 anomalies. This i nformatio n included (1) NWS radiosonde wi nd s, temperature, and moisture from Barrow ; (2) pressure, height, and temperatur e fields 

ob t ained from NNC maps ; (3) meteorologi cal va ri ables a t BRW; and (4) air mass 

traj ec torie s. 

Two broad regio ns were identified as the sources of air mass es associated 

with the CO 2 a nomalie s at BRW : the Arctic and North Atlantic regions. Arctic 

air ma sses we re recognized by cold t emp e ratures , low moisture , and l ong residence times in the Arctic . These air masses were found to be high in CO 2 and 

aerosol mass load i ng. The modified oceanic air masses , characterized by relative warmth and moisture , we re , in contrast, low in CO 2 and aeroso l ma ss loading. 

During low-C0 2 episodes, oceanic air cent ered between 950 and 850 mb 

fl owed into the Arctic. Pacific air was brought northward over Pt . Barrow by 

intense cycl oni c circulations i n the Bering Sea -Aleutian-Gulf of Alaska region 

a nd /or high-pre ssu r e systems over Alaska and western Canada . Inte nse cyclones 

over eastern Canada were responsible for the less-frequent arrival of air from 

the North Atla ntic r egion. At the same time, the s urface layer of the a tmosphere, being domi nated by high pressure over the North Ame rica n or Siberian 

sectors of the Arctic Ba sin, was relatively cold and dry. Surface temperatures were 10°-15°C coo l er than at t he top of the consequent surface-based 

84 
inversion layer. With the modified oceanic air aloft, moisture levels in this 

surface-based Arctic air layer, although at considerably lower levels, tended 

to follow those aloft. This provided evidence of eddy turbulence and/or gaseous diffusion through the inversion layer. The surface-based Arctic layer 

varied in depth, and on a few brief occasions, increases of surface temperature and moisture to levels comparable with those of the Pacific or Atlantic 

air aloft indicated the actual e limination of the Arctic layer. On these 

occasions, the high aerosol light-scattering values typical of Arctic air during winter at BRW diminished to values approaching those typical of su.nmer 

(Murphy and Bodhaine, 1980). 

In high-C0 2 episodes, Arctic air was present in a deeper layer, us ually 

extending through the entire depth of the troposphere. The Arctic air was 

drawn into the BRW area by cyclonic circulations over the North American 

sector of the Arctic Basin and/or anticyclones over the Arctic Ocean or 

Siberia. The trajectories suggested residence times in the Arctic of longer 

than 10 days for these air masses. Low-CN counts for some of these cases, i mplying a well-aged aerosol, suggested a long residence time over the Arctic 

Ocean, whereas higher CN counts for other of these cases and southeasterly 

airflow suggested fresher aerosol from Arctic land areas such as Alaska and 

Canada. 

Regarding the high-C02 concentrations with deep Arctic air masses, the 

long residence times in the Arctic seem consistent with both a natural CO 2 

source from the Arctic Ocean (Kelley and Gosink, 1979) and a polluted Arctic 

air reservoir (Barrie et al., 1981). In future studies, surface ozone data 

and daily air chemistry samples obtai ned at BRIV (GMCC Summary Report for 1980, 

DeLuisi, 1981, pp. 113-116) may clarify the relative importance of midlatitude 

anthropogenic sources and the Arctic Ocean with regard to CO 2 concentration at 

BRW. 

4.6 Calibration of Pollak Condensation Nucleus Counters 

4.6.1 Introduction 

The Pollak CNC (~letnieks and Pollak, 1959) has been adopted as a secondary standard for all CN measurements at the GMCC stations. A Pollak CNC is 

located at each GMCC station and is compared daily with the G.E . automatic CNC 

to ensure that the calibration of the automatic instrument is maintained over 

a l ong time period. The original calibration of the Pollak CNC (Polla k and 

Metnieks, 1960) used a photographic absolute CNC, and it ha s since been assumed that any instrument manufactured to Pollak's specifications would inherently have the same calibration. 

4.6 . 2 Results 

The seven Pollak counters used in the GMCC program were manufactured by 

BGI, Inc., Waltham, Mass., to the exact specifications given by Metnieks and 

Pollak (1959). These instruments have BGI serial numbers 13, 15, 16, 19, 20, 

21, and 22 . To ensure calibration of the Pollak counters, G~lCC maintains a 

photographic CNC similar to the one described by Winters et al. ( 1977) and a 

mobility analyzer similar to that of Liu and Pui (1974). 

85 
During the summer of 1981, a laboratory experiment was performed in which 

three Pollak counters (SN 19, 21, 22) were compared with the GMCC differential 

mobility analyzer. The results of this experiment were reported by Miller and 

Bodhaine (1982a). The aerosol generation scheme, shown in fig. 46, used an 

atomizer to generate a polydisperse aerosol, a differential mobility analyzer 

to select a monodisperse aerosol of a give n size, and an electrical aerosol 

detector to measure aerosol concentration. This system can be used to generate a monodisperse aerosol in the size range of about 0.01 < d < 0.1, where 

d is the aerosol diameter in mi crometers. 

The results of the experiment are shown i n f ig. 47. The three GMCC 

Pollak counters were within about 7% of each other and coincided a lmost 

exactly with the results of a similar experiment by Liu et al. (1975) . The 

Pollak eNC concentrations were about 30% lower than the electrical aerosol 

detector concentrations. 

r------ ----:1 

I Absolute I 

I Filler I 

Compressed Air_-1-:::--t:J<:)-jDryer , f--0:$::;=====)i ~~g~l~o~ ___ __ J ,--------------------l I FIOVlm~ter Filter 

I - Valve Dilution I H.V.Power r-----' Dry Air 

I S I Diffusion : 

I upply " ,_ , '~; I [=r~~i.-----[c=~}_++'_{~~~~I~I I I I t I 

Kr.SS I I 1 

Neutralizer L _ ~~c~ ~:I J : -.:' RE : 

DIFFERENTIAL : ~ ,,, i 

MOBILITY I Atomizer I 

ANALYZER I L ____ J I 

Valve Filter Excess-l--:ci; __ :::~~~:r111 Air Flowmeter ' ( Monodisperse 

Aerosol 

1,---------------1 

I , ELECTROMETER I 

II CURRENT I 

I I SENSOR I 

II I 

" I 'I Valve 11 : L ___ __ _______ _ _______ '1 I 

I 

I 

I 

Flowmeter Valve 

L ___ __ _________ J 

Figure 46.--Diagram of the monodisperse aerosol generation scheme. 

86 
",. 

-Np .. tl e 

--liu el l1.{197S) Np = 0 911 N.Ogn 

-<- POI1~ k 19 NO = 0_899 Ne 0977 

- Pol1ak2 l Np ,,0.913 N. O.gao 

~---- Pollak 22 Np = ° mNe 0_96 1 

---- AIID .. 1~ Np =0913 N. O.979 

",. ",. Eleel"cal Counler. N. pani~I •• em-3 '"' 

Figure 47.--Intercomparison of Pollak 

CNC calibrations. 

4.7 Supersaturation and Expansion Ratio s in 

Condensation Nucleus Counters 

4 . 7 .1 Introd uction 

In Aitken ' s experiments i n 1880 on the physics of condensation processes 

(Knott, 1923), he concluded t hat "if there was no dust in the air there wo uld 

be no fogs , no c l ouds, no mists, and probably no rain . " In the next few years 

Aitken constructed seve ra l i ns truments , each of which produced an expansion of 

an air sampl e. The resulting s upersatu ration caused droplet growth on the 

"dust particles" in the air. His final version , the Aitken pocket counter, 

was used for many years as the only available mea surement device for eN. 

Subsequent work by Wilson ( 189 7), Scholz (1931), Bradbury and Meuron 

(1938), and Nolan and Pollak (1946) led to the development of the photoe l ectric CNC in its present form (Pollak and Metnieks , 1960). It is this 

instrument that was adop ted as t he GMCC reference standard for CN measureme nts. A histori ca l review of the development of CNC's has been presented by 

Miller and Bodha ine ( 1982b) . 

In the course of their review, Miller and Bodhaine discovered incons i stencies i n t he me thods of ca l culation of expansion and s upersaturation in 

CNC's . I nterestingly, t he confusion in the literature arose from a lack of 

apprecia ti on of a thermodynamic process known as a free expansion. 

4 . 7 . 2 Expa nsion and Supersaturation 

An expansion instrument may be constructed to operate adiabatically by 

t wo different thermodynami c processes, apparently first explained by Herzog 

(1935). In a vo lume-defined expa nsion produced by a moving piston, work is 

done by t he pist on and the inte rnal energy of t he gas change s . In a pressuredefined expan sion , or free expa nsion, in whi ch the initia l vo lume is allowed 

to expand i nto an adj acent evacuated vesse l by me ans of a valve, no work is 

done on the gas and the i nternal ene r gy does not change . The instruments of 

Ai tken, Wilson, and Scho l z were all piston operated, whereas the Pollak 

co unter and the Gardner count e r a re both f ree- expansion instruments . 

In the case of a piston-operated instrument, the relationship between the 

initial and final pressures and temperatures is given by 

87 
Tf = (Pf ) V 

T. P. 1 1 

(1) 

where y is the ratio 

at constant volume. 

and volumes is given 

of the specific hea t of air at constant pressure to that 

The relationship between the initial and final pressures 

by 

(2) 

In the case of a pressure -defi ned i nstrument in whi ch the samp l e volume 

is allowed to expand by means of a va lve , the re lationship between pre ss ures 

and temp eratures is still given by (1 ). However , the relationship between 

pressures and volume s , derived by Herzog (19 35) , is complicated a nd is not 

given by (2). In the case of a Pollak counter, whi ch is expa nded to th~tmosphere, t he final vol ume is not define d and the temperature depression mu s t 

be calculated from (1). In the special case of a Gardner counter, which expands to an evaculated chamber, the relationship between pressures and volumes 

is given by 

from which the temperature depression may be calcul ated using (1) . 

Saturation ratio in a n air sample is defined as the ratio of the actual 

water vapor pressure to the saturation vapor pressure in the sample. There -

fore, the saturation ratio achieved in an instrument after expa nsion is found 

from 

S = 

e 

where e is the wa t er vapor pressure immedi a t e l y aft er 

c ondensation) and e is the saturation vapor pressure s 

expa nsion (but before 

of the sample after expansion and at t he final temperature. 

fore the expansion, 

Since the air sample is saturated bee 

e (T.) 

s 1 

and 

S = 

e (T.) 

s 1 (3) 

Equation (3) is the co rrect exp re ssion to calcul ate the sa tu ra tion ratio 

achieved in either a piston-operated or a free-expansion-type instrument. An 

equivalent expression for use only in a piston- operated instrument is 

88 
S = 

Supersaturation is defined as the excess above a saturation ratio of 1 and is 

sometimes exp ressed as a percent. In general , therefore, 

SS = S - 1 

SS (%) = (S - 1) x 100 

A more compl e t e discussion of the t heory of expansion, supersaturation, 

and condensation can be f ound in Miller and Bodhai ne (1982b). 

4 . 8 Co rrection to Long-Term Umkehr Data Using the 

MLO Solar Transmission Record 

4.8 . 1 Introduction 

The high sensitivity of MLO so l ar transmission measurements to stratospheric aerosols lends itself as a source for a virtually continuous set of 

optica l thickness data for stratospheri c dust . As far as ca n be determined, 

there exists no comparab le data set for the Northern Hemisphere that is as 

long as the tlLO record (1957 to t he p resent) . Rather coincidentally, systematic Umkehr observa ti ons of t he vertical profile of ozone were started at 

several stations i n the Northern Hemisphere near the same time as the MLO 

transmission measurements were sta rt ed . Consequently, it is possible to investigate the relationship between stratospheric aerosol-induced errors and 

specific features seen in the long-term Umkehr ozone profile data. This report bri e fly describes the preliminary res ults of such an investigation. 

4.8.2 Results 

Figure 48 s hows a slightly smoothed plot of the entire record of monthly 

averaged solar transmission measureme nts made a t MLO. De tails of the record 

are given by Mendonca et al. (1978). On the assumption that the span of years 

preced ing the eruption of Agung in 1963 was representative of a climatically 

quiescent pe riod during which the stratosphe r ic dust was of a background character , it is possible to estimate enhancements in stratosphe ri c dust optical 

thickness whenever a departure (decrease) in transmission from the mean of the 

quiescent period occurs. 

Figure 49 s hows departures f rom t he 2- yr ave rage of the pre-Agung qui escent period. The 2-yr average means t hat a 2- y r cycle rather than the annua l 

cycle ha s been removed because t here appears to be some indication that a biennia l cycle exists in the transmission re cord, although this ha s yet to be 

proved. The departures shown in fig. 49 essentially represent an estimate of 

the optical thickness of a stratosphe ric dust enhancement. From Beer's law a n 

estimate of optical thi ckness 6't is given by 

6T 61 =- t T 

89 
0.95 r--~--~---~-~~~-_.__' 

0.9\ 

oooL-~-L~~L--L~ ____ ~-L~_L-~ 

1957 1959 1961 1963 1965 1967 1969 1971 1973 1975 1977 19791981 

Date 

Figure 48. --Plot of monthly averaged 

transmission measured at MLO. The 

plot has been slightly smoothed. 

O.«)825 

0.00000 

-0.00825 

-0.01250 

- 0.01875 

- 0.02500 '--L---L_L---'----"'--'------'-_'---'----'_-'----" 

1957 19591961 1963 1965 1967 1969 1971 197319751977 \979 1981 

Dale 

Figure 49.--Plot of transmission 

differences after s ubtracting 2-yr 

cycles calculated for the quiescent 

period prior to Agung. Da t a from 

fig. 48 were used. 

where T is the mean transmission and 6.T is the departure in transmission. 

However, this optical thi c kness is representative of the solar flux integral 

over a ll wavelengths in t he so lar spectrum whereas a value near 330 rum is requi red here. ~lodel calculations of transmission using LOWTRAN show that t.t 

is best applicab l e at a wavelength somewhe re between 700 and 800 nm, and th~t at 330 nm the op ti ca l thickness is approximately 2 times greater than the 

transmission for all wavelengths. Figure 50 is a plot of at vs. time . Multiplication of t.tt by 2 . 2 will give the value of the optical t5ickness at 330 nm. 

The error to Umkehr ob serva tions (made in the Northern Hemisphere) is 

estimated usi ng t.tt and the results of Dave et al . (1980), and invoking the 

reas onable ass umptlon that the error is linear with optical thickness. Figure 5 1 (a) s hows four panels of average ozone co ncentration in Umkehr layer 9 

using data from six stations located in Europe and Japan. The ordinate represents departures from the long-term average with the annual cycle removed, and 

the abscissa is time in years. The uppermost plot is the uncorrected basic 

da ta; the next includes the s tratospheric aerosol correction; and the lower 

two plots are unwe ighted, seven-point smoothed versions of the corresponding 

plots above. Some obvious differences are seen between the uncorrected and 

0.03125 r-r--,--,------c-,------,-.,-~-_.__, 

0.02500 

0.01875 

0.01250 

O_1Xi625 Figure 50. --Estimates of enhancements 

in stratospheri c dust optica l depth 

0.00000 at t at ~l LO using data from fig. 49. 1957 1959 1961 1963 1965 1967 1969 1971 1973 1975 1977 1979 1981 

Dale 

90 
i~~~':;;-('l iF;: ] 

UE~:;"~v~""~;~=; 1 U::~~~'~;:~~~ 1 

Smoothed Mon thly Aver<lges . A.C.R. 

Ilt:==. =' =::1 

F t ~ g-3 

o 

U_s ! 

1964 1966 

Smoothed Corrected Averages · AC.R. 

1968 1970 1972 '974 1976 1978 

Smoothed Monthly Averages· A.C.A. 

Utr--~ ~~ -~ -_ -~ ~~ ~_ -~ ~~ -_==1 

Smoothed Corrected Averages · A.C.R. 

c "f -1 g 11 

• 

~ r----------------------~ 11 u _" L ___ ~ ____ ~ __ _L ____ L_ __ _L __ ~ ______ ~_J 

1964 1966 1968 1970 1972 197A 1976 1978 

Smoothed Monthly Averages· A.C.R. 

v==[ =< =: : ~, 1 

I1E 

Smoothed Corrected Averages· AC.A. 

1964 1966 1968 1970 1972 1974 1976 1978 

Smoothed Monthly Averages· A.C.R. 

n=t =-:==] 

Smoothed Corrected Averages· A.C.R. 

@ =: : :1 

1964 1966 1968 1970 1972 1974 1976 1978 

Figure 51.--Umkehr data for three stations in Eu rope C35, 68, and 70) and 

three stations in Japan C7, 12, and 14) for Ca) l ayer 9, Cb) l ayer 8, Cc) 

layer 7, and Cd) layer 6. Data are in terms of concentration C~ mb ) departures 

from the mean vs. time with the annual cyc le removed. 

91 
corrected plots. There is reas on to believe that the corrections made in 1964 

and 1965 may be overestimated, becaus e a stratospheric dust gradient probably 

existed between the latitude of MLO (19°N) and the European and Japanese stations (located between 30° and 50 0 N). 

Figures 51(b-d) are similar to fig. 51(a), but show results for layers 8, 

7, and 6, respectively. No corrections were made to layer 5. Note that the 

magnitude of t he correction decreases as the layer altitude decreases. 

4.8 . 3 Conclusion 

The MLO transmission data are useful for correcting Umkehr ozone profile 

errors caused by the presence of stratospheric dust. However, the latitude 

differences between MLO and the Umkehr stations probably introd uc e a bias in 

the corrections because a latitude gradient of dust concentration may exist. 

Further work on the horizontal diffusion of stratospheric aerosol will be 

needed in the present correction procedure. In the future , it would be wise 

to have stations measuring stratospheric dust at several different latitudes 

between 30° and 50 0 N. 

4.9 Comparisons between Backscattered Ultraviolet, Standard Umkehr, 

and Short Umkehr Me as urements of Ozone Co nc entration 

A comparison of ozone concentration at 45 km (Umkehr layer 9) observed 

coincidentally with the BUV and Umkehr measurement methods was presented by 

Fleig e t al. (1981). The comparison consisted of an annually averaged percent 

deviation of Lhe BUV with respect to the Umkehr from 1970 to 1977. This 

comparison is shown in fig. 52 as the dashed plot. The year 1977 was omitted 

because only a few comparisons were possible. The plot shows an obviously 

increasing difference with time until 1975 when a rather serious departure 

from this trend occurred. This happened to be during the time of enhancement 

in stratospheric dust from the eruption of DeFuego (fall 1974). 

The MLO transmission data were used to correct Umkehr me asurements made 

during the period 

solid-line plot . 

'" 5 

::; 

=> 1- -_-±-

0 , > , 

of comparison. The corrected comparison is shown as the 

The correction for stratospheric dust not only lowers the 

A, 

I \ 

=> 't"+--i/ en 

~ -5 

c 

I 

\ 

\ 

\ 

Figure 52 .--Comparison between BUV 

and Umkehr (UMK) observations of 

ozone in Umkehr layer 9 over Arosa, 

Switzerland. Points are annual 

averages in terms of percent differe nce with the Umkehr as a reference. 

The dashed line is the comparison 

published by Fleig et al. (1981); 

the bars are for standard error. 

Q 

<;; -10 

'

.. " 

-15 [ 

0 

70 71 72 73 74 75 

Year 

76 

The solid line is the result of 

stratospheric aerosol error corrections to the Umkehr; bars are for 

2.5% uncertainty in optical depth. 

92 
Table 28.--Comparison of SBUV, Umkehr, and short Umkehr 

obs erva tions using 1978 Boulder data 

Layer no. UMK-SBUV'" Short-UI'lKt Short-SBUV 

(%) (%) (%) 

9 3.8 -0.3 3.5 

8 -6.3 7.5 0.7 

7 -3.7 0.64 -3.1 

6 10.5 -12.5 -3.3 

5 9.1 -12.1 -4.1 

4 -6.8 11. 7 4.1 

3 1.1 24.3 25.7 

2 27 8.6 37.9 

1 -43 -5.1 -45.9 

"'SASC (1981). 

tMateer and DeLuisi (unpublished). 

original comparis on by 5%, but also removes most of the large anomalous 

departure seen in 1975. On the whole, the BUV ozone data appear to have 

changed by 15% during the 7-yr period. 

Another type of comp arison between coincident SBUV and Umkehr observations was given in an informal report by the Systems and Applied Sciences 

Corporation (SASC, 1981) BUV data processing team. Their comparison is s hown 

in the second column in table 28. The data are from the SBUV and the Boulder 

Umkehr (U~lK); SBUV is the reference for the difference. The third co lumn 

shows a comparison between concurrent short and standard Umkehr mea sureme nts 

also made at Boulder (C. Mateer and J. DeLuisi, unpublished), but not necessarily during the time of the SBUV fly-by. By use of this comparison, the 

Umkehr-SBUV comparison was transformed into a short Umkehr-SBUV comparison, 

and an improvement is noted in layers 4-9 where agreement is now 4% or better. 

The improvement is most likely due to the use of better ozone absorption 

coefficients and ozone profile statistics in the short Umkehr inversion. No 

improvement is noted in layers 1-3 where the Umkehr is very insensitive to 

ozone, and in fact, the agreement is worse than that of the standard Umkehr. 

At this time the marked disagreement cannot be explained, but an investigati on 

of the cause is planned. Before this is done, however, an attempt will be 

made to use coincident SBUV and short and standard Umkehr measurements to 

repeat the type of comparison done for fig. 52. The use of coincident data 

will give assurances that a time-dependent bias is not responsible for the 

present result. 

These kinds of comparisons appear to hold promise as means for monitoring 

changes in BUV response to stratospheric ozone. It is extremely important 

that a BUV satellite be continuously checked for performance changes if the 

measurements are to be used to search for trends in upper-stratospheric ozone. 

93 
4.10 Cloud Chemistry and Radiation Experiment 

a t Whiteface Nountain, N.Y. 

4.10.1 Introduction 

A summer experiment on White face tlountain was organized by scientists 

from NOAA a nd from ASRC at Albany to investigate possible augmentation of 

c l oud absorption of solar radiation caused by aeroso l scavenging in the cloud . 

Cl oud-droplet size spec tra have been observed to be altere d by aerosols from 

anthropogenic sources (Barrett et al., 1979) . Thus, if these aerosols possess 

significant radiation absorption properties, then the solar radiation absorbed 

by the c loud s is likely to be i ncreased whether the aerosols are distributed 

in the c l oud water or rema in as aerosols interspersed among the cloud dropl ets. 

The basic research strategy employed in the summer ex periment was to 

( 1 ) collect cloud water at the Whitefa ce Nountain ASRC facility a nd analyze 

the residue , after evapora tion of the water, for optical absorption; 

(2) identify chemi ca lly the nonaqueous constituents of t he cloud water; 

(3) characterize the optical properties of the free aerosols by co llection and 

l aboratory ana l ysis, by meas uring their size distribution, and by measuring 

their optica l extincti on properties using sunphotometry; (4) comput e the 

op tical properties of the modified cloud using Nie theory and the results of 

( 1) and (3); and (5) estimate the excess absorption of solar radiation by the 

cloud, lls ing radiative transfer ca l culations . 

4.10.2 Preliminary Results 

Preliminary results from the basic strategy are given in tab l e 29, which 

partially summarizes the nature of the s ubstances in the cloud water. Figure 53 s hows the imaginary (or absorption term) of the complex refractive 

Table 29 .--An exampl e of some characteristics of 

water sampled at Whiteface t!ountain 

Chemistr}, anal},sis'" 

= F Cl NO) S04 Na 

1. 06 2.8 0.5 2.4 1.9 

Microscopical ana lysis 

Biological 50% 

Nineral 35% 

Indus trial 15% (black , ye llow, red) 

SEN anal}'sis 

(1 ) Sulfate is an integra l part of the cloud water. 

(2) There is evidence of upwind industrial pollution . 

the cloud 

NJI/ 

0.3 

(3) Nat u rally occurring organi c aerosol makes identification of 

industrial or l ocal pollution sources difficult during the 

sunmler . 

;'Ion chromatography (ppm), 26 June 1981 . 

94 

K+ 

3 .3 
10- 1,--.----.----,---,---" 10 - 1

,--.------,-----,------.------" 

Aerosols 

10/14 

10 -2 Cloud Water 10 -2 

10115 

~:::=.... ___ 7_ii 

7128 

8/3 

10 - 3 10 - 3 

7128 

10 'L-~~-~~-~~-~~-~~ 300 400 500 600 700 10-'~~------~----~----~~--~~ 

300 400 500 600 700 

,(nm) ,(nm) 

Figure 53.--Imaginary term NUl of the compl ex refractive index of cloud water 

residue (left) and free aerosol (right) . The real term is fix ed at 1.5. R1 

designates a rime ice sample (collection time unknown) . 

index NIH of the s ubstances extracted from cloud water (left figure) and the 

free aerosol (right figure) vs. wavelength. An NIH of 0.01 is considered to 

be quite strong and approaches that found in an urtian atmosphere . An apparent 

relationship between NUl and cloud water pH (measured at IYhiteface) seems 

quite real. An example of such a relationship is seen in fig. 54 in which NIH 

data at 500 nm from fig. 53 have been plotted vs. pH. The hori zon tal bars 

represent the maximum and minimum of the pH values that constituted the 

average of a large number of readings. If anthropogenically derived aerosols 

are more strongly absorbing, very likely because of the presence of black 

carbon , then it is also likely that the pH decrease is due to anthropogenic 

sources. 

Further confirmation of the relationshi p between absorption and pH is 

seen in fig. 55 where attenuation of light (or filter blackness) vs. hydrogen 

ion concentration is plotted. Note that the rainwater samples from Illinois 

are included in these data. 

95 
z 

10- 2 r-----~-----__,----__, 

H 

10-''------'-------0---------'. 3 4 5 6 

Cloud Water pH 

Figure 54.--A series of point s t hat 

imply a relationship between NIH 

(see fig. 53 ) and acidity (pH) of 

cloud water. Horizontal bars 

represent the maximum and minimum of 

the pH values that constituted the 

average of many readings. 

c 

.Q 

... 

~ 

c 

.!! 

<i 

90 

80 

70 o Whiteface Cloudwaler 

«> llionols RaInwater 

60 

50 ....... r '" 0 98 

" 

30 

0 

20 

" 0 

0 

0 

0 0.0 2.0 30 40 

!H+] X 10' 

Figure 55.--A series of points that 

implies a relationship between 

absorptivity of cloud water residue 

and t he hydrogen ion concentration 

of cloudwa t er . Corre l ation coefficient r i s given (H. Rosen, personal 

communication). 

Ta ble 30.--Calculations* of c l oud optica l properties using 

cloud water residue data 

Case ~las st Bext§ 

(mg) (em-I) 

DroEle t ~l e 

I 40 2 . 2805 X 10-· 

II 22 2 . 2805 x 10-· 

III 3 2.2805 x 10-· 

Accumulation mode 

6.355 x 10- 7 

Combined mod e 

I 40 2.2864 X 10-· 

II 22 2.2864 x 10-· 

III 3 2.2864 x 10- 4 

;"Calculations were performed by E. Barrett of ERL . 

tHa ss of residue per 2 £ of collec ted cloud wa ter. 

§B = optical extinction . ext 

~-~WIi = albedo of single scatter. 

WIi"ck 

0 . 999974 

0 . 999987 

0.999996 

0.955 

0.99985 

0.99986 

0.99987 

NOTE: Index of r efraction used in t he se calculations was N = 1.55 - 0 . 009i, 

as mea s ured by E. Patterson of the Georgia Institute of Technology. 

96 
Table 31.--Calculated fractional absorption in a cloud* 

Op tical depth Thickness Absorption for Absorption for 

Wo = 0.9999 Wo = 0.999 

8 0.35 0.0009 0.0081 

16 0.7 0.0015 0 .0148 

32 1.4 0.0029 0.0272 

64 2 . 8 0.0055 0 . 0467 

*Initial input variables: G = 0.85 is the Henyey-Greenstein factor; 80 = 60· 

is the so lar zenith angl e; and F. = 0.5 is the value of the incident solar 

flux. 

Typical s iz e distribution measurements of the free aerosol and cloud 

droplets, made at Whiteface, were used to calculate the albedo of single scattering Wo shown in table 30. In the droplet and combined modes, Cases I, II, 

and III refer to the mass per uni t volume of cloud water. B is the ext ·· . 1 h' k ext loctlon optlca t l C ness. 

The optical characteristics of free aerosols are given in table 30 under 

the heading "Accumulation mode, " and the optical characteristics of the 

combined droplet and accumulation mode are given under the heading "Combined 

mode." A comparison between r es ults for the droplet mode and the combined 

mode show an order of magnitude difference in WOo 

The impact on the absorption of solar radiation in a cloud can be illustrated by a model calculation of fractional cloud absorption for two different 

values of Wo and four different optical thicknesses. Calculations were done 

by M. King of NASA, Goddard . His calculations are s hown in table 31. In this 

table "G" stands for the Henyey-Greenstein or g factor, 80 is the solar zenith 

angle, and the incident flux F. is 0.5 of the solar constant. The c l oud 

optica l dep th is transformed into linear thickness using the calculated volume 

extinction given in table 30. The Wo values calculated from the Whiteface 

Mountain experiment are in the range used for the calculations in table 31, so 

it is believed that these results represent reasonable estimations of the 

increased solar radiation absorption in clouds caused by aerosols scavenged 

and released in cloud processes. However, there is no doubt that a greater 

amount of experimental work is needed to develop a clearer understanding of 

the range and variability of the cloud properties observed, and the reliability of the estimated cloud radiative properties. 

The following were participants in the 1981 Whiteface ~Iountain experiment. 

ERL SUNY 

E. Barrett R. Castillo 

B. Bodhaine R. Cheng 

J. DeLuisi Other universities E. Dutton 

B. Mendonca T. Cahill 

R. Pueschel E. Patterson 

L. Stea rns H. Rosen 

97 
4.11 Calibration of a Solar Infrared Hygrometer 

Five so lar i nfrared hygrometers were acquired by GMCC in 1976-1977. 

Properly calibrated, these instruments accurately measure narrowband absorption of solar radiation by atmospheric water vapor, from which total 

vertical water vapor amounts can be inferred. Although a prototype instrument 

had been satisfactoril y ca l ib r ated by mea ns of a sophisticated t heoretical 

approach and substantiated by high-altitude aircraft measurements, the instruments delivered to GMCC had no calibration . The prototype calibration was 

destroyed by an electrical malfunction before it could be transferred to the 

G~ CC instrument . Lacking facilities t o repeat the original prototype calibration, a semiempirical approach has been used in an effort to perform a reasonable calibration of the GMCC solar hygrometers . 

The basic instrument consists of two narrowba nd interference filters with 

an optical arrangement such that the solar radiation passing through each 

filter is alternately allowed to fallon a single gallium arsenide detector. 

A background signa l is s ubtracted from each filter channel signal by the use 

of a chopper wheel rotating at 30 Hz i n front of the detectors. The resulting 

signal is demodulated, yielding two 0- to 10-V signals, each linearly proportional to the solar intensity in the respective band passes. The instrument 

optics are sea l ed against the weather and heated to a constant temperature 

above ambient temperature. 

The principle of the instrument involves the measurement of the ratio of 

solar intensities in two nearby spectral bands, one (1.1344 ~m ) with strong 

water vapor absorption and the other (1.060 ~m) with virtually no water vapor 

ab sorption. Then if all other of the attenuator's extinction ratios between 

bands are constant, the variability of the measured intensity ratio is due 

entirel y to water vapor. This is expressed mathematically by the calibration 

equation, which is combined with the total water vapor inference expression as 

derived in the following. 

The extinction of monochromatic electromagnetic radiation is expressed by 

Beer's Law : 

(4) 

where IA = spectral intensity as depleted by the medlum, lOA = spectral 

intensity before entering the medium, 'A = optical.parameters of the medium, 

and m = relatlve path length through the medlum (alr mass). ThlS expreSSlon 

holds for atmospheric cases in narrow spectra l intervals that only approximate 

monochromatic radiation, except where water vapor is a dominant absorber in 

the interval . An expression often given, equivalent to (4) but describing 

extinction due to atmospheric water vapor, is 

where, is vertical optical depth of water vapor and n is a variable dependingWon the particular band and bandwidth under consideration. 

For any given spectral band in the atmosphere, the extinction of sunlight 

will be caused by several attenuators, and the cumulative effect is given by 

n -(, m) • e w 

98 
Taking the ratio of two wavelength (AI, A2 ) bands, one containing H2 0 and t he 

o the r the same attenuators except H20 , gives 

= 10 , . "2 

n - (T m) 

e w 

(5) 

Now considering the GMCC solar IR hygromete r with its linea r-withintensity voltage output a nd the assume d constant ratio between IVavelengths of 

Rayleigh and aeroso l optical depth, (5) becomes 

where 

lOA ' 2 

n ~ c' - (, m) = V e w 

02 

V

" 

Vz , VOL, and Vo, are voltages associated with IAl' I

Az ' 10AI' and 

and C' is a constant 

Assuming t hat the ratio of extraterrestial radiation at the two wave -

lengths is consta nt and taking the natural log of both sides of (6) gives 

I n ~) = In C - ('w m)n 

where C is a constant. 

The vertica l optical depth of water vapor can be expressed as 

, = K P6 

w 

(6) 

where K is an absorption coe fficient and Po is the verti ca l amount of water 

vapor expressed as equivalent liquid amount. The pressure and temp erature 

de pendency of K will be discussed later . The resulting expression for total 

water vapor is then 

Po = 

1 

K m 

(7) 

Several op tions are now possible to det~rmine the constants K, C, a nd n. 

The straightforward approach used and reported her e was to calculate C from 

filt e r transmission curve s , detector spectral re sponse, different channel 

operations , a common extraterrestrial so lar spectrum, theoretical Rayleigh 

extinction, and typical aerosol s pe ctral extinction. The constant C is equal 

to t he output vo ltage ratio in the absence of any water va por. The constants 

na nd K were then determined by a least-s quares fit t o a form of (7) using 

data on several ideal days whe n V2/V l wa s meas ured at various va lues of m (air 

mass), a nd Po was de termined from the NWS radiosondes. The cons tants determined for two GMCC IR hygrometers are given i n table 32. 

This calibra tion procedure co ntains many uncertainties, and the resulting 

constants have a limi t ed water va por range of applicability . The r a nge of 

appli cability for the constants K and n is determined by the ra nge of water 

vapo r amounts encountered during the calibration process , because the s hape of 

the water vapor extinction curve changes as more individua l abso rption lines 

99 
Table 32.--Values of constants in eq. (7) for 

two GHCC IR hygrometers 

IR hygrometer K C n 

No. 4 1. 04 0.71 0.50 

No. 1 1. 20 1. 02 0.51 

become saturated. The GNCC hygrometers were cal ibrated on very dry, st able 

days (Boulder, Colo., in January) and t he calibration data indicate a constant 

absorption curve shape as long as the total slant-path water vapor (m Po) does 

not exceed about 2.0 Col . For the i ntend ed field use of these instruments at 

HLO and SPO, th is ra nge restriction presents no major problem. The un certainties accumulate from almost every step of the ca libration process , but the 

total ab so lute uncertainty is believed to be l ess t han ±10% i ncluding possible 

er ror in the water vapor deternl ined from the radiosonde. I n an informal 

i ntercomp arision with the WPL mi crowave water vapor meter , spanning several 

weeks, the net difference between the two measurements was less than 2% 

a lthough some individual comparisons differed by as mu ch as 20%-30%. The 

large individual measurement differences probably resulted from line-of-sight 

differences since the vertical-looking microwave inst rume nt was located in 

Denver while the GHCC instrument was in Boulder, 26 mi apart. However, the 

sl ant path of t he IR hygrometer is in the general direction of Denver. 

The long-term stability of the IR hygrometers is uncertain aL Lhis time 

and can best be moni t ored by repeating the calibration process, although the 

number of days s uitable for the cal ibration are very limited and instruments 

sent to the field ha ve little opportunity for recalibration . 

An additional complication in the water vapor mea s urement is the pressure 

a nd t emp e r atur e depende ncy of the effective absorption coefficient K. Since 

no vertical reso lution is possible with t he IR hygrometer, K is taken as a 

constant. The error involved in doing this will depend on the deviation of 

actual water vapor profil es from those used during the calibration of the 

hygrometer. Ideally the hygrometer would be us ed at a location the same as 

where it was ca librated; this was not the case for the GHCC hygrometer. To 

somewhat crudely account for the change in e l eva tion between Boulder and the 

f ield sites and t o s ome extent the differe nce be tween the vertical vapor 

profiles, a pressure and t empe ra ture correction expression for water vapor 

scale height was us ed. The expression us e d here was essentially t hat suggested by Lacis and Hansen (1974) and used in LOWTRAN 5 . 0 (Kneizys et al., 

1980), with t he sca le heights determined from radiosonde data . SPO scale 

heights we r e estimated from an exponential decrease with height. 

Correcting for scale heights between the calibration location and the 

field sites r esults in actual water vapor amounts whereas correcting between 

the field site a nd the sea leve l pressu re and tempe rature yields equivalent 

sea l evel absorber amounts. All data reported here will be actual amounts. 

Table 33 gives the monthly ave rages for 6 months of total vertical water 

vapo r measurements at NLO and severa l measurements at SPO. The comparison 

with the 20 - yr average record at Hi l o is given only for general comparison and 

100 
Table 33 .--Honthly averages for 6 months of total vertical water vapor 

measurements at HLO and several measurements at SPO 

Date Gncc IR Hilo radiosonde 

hygrometer 20-yr average 

(cm) (cm) 

HLO 

Sep 1981 0.47 0.40 

Oct 0.34 0 . 42 

Nov 0.42 0.42 

Dec 0 . 32 0.37 

Jan 1982 0.30 0.37 

Feb 0.22 0.33 

SPO 

15 Jan 1982 0 .1 3 

5-10 Jan 1982 0 . 12 

23-25 Jan 1982 0 . 07 

i s not directly comparabl e because the 20-yr record is compiled for all days 

and the IR hygrometer operates only on clear days . Another possible bias in 

comparing the Hilo radiosonde with MLO IR hygrometer measurements results from 

the time-of-day differences; the radiosonde flights were at 0200 and 1400 LST, 

and most IR hygrometer data were obtained in the time interval 0800-1000 LST. 

There is large variability on many time scales in the HLO amounts, with 

the extremes ranging from 0.08 to >1.2 cm during a 6-mo period. A tripling of 

water vapor in a few minutes has also been recorded. The observed variability 

in the record is believed to be real since the short-term measurement precision is better than 0.005 cm. Discrete measurements at SPO, as opposed to 

con tinuous monitoring at HLO (courtesy of NCAR/High Altitude Observatory), 

have shown relatively little variabil ity day to day. 

4.12 Sunphotometer Inter comparison 

Several sunphotometers of modern design were intercompared by means of 

actua l atmospheric observations in Boulder over a period of 2 months in the 

fall of 1981. Twelve instruments of five different designs and manufacture 

were compared. The results indicate that current modern sunphotometers are 

capable of measuring spectral atmospheric optical depth to within ±1.5% of the 

values obtained by a reference instrument with which the sunphotometers were 

initially compared. This translates to a measurement precision, between 

instruments, in terms of aerosol optical depth of 0.005 (base e) units at 

500 om and :0.01 units at 380 om. Details of the intercomparison are given in 

Dutton and DeLuisi (1982). 

The instruments participating in the intercomparison were calibrated in 

two different ways. One calibration technique was the commonly used Langley 

101 
plot method that results in a n ind epe ndent calibration of each instrument. 

The other calibra tion proced ure was to define a reference optical depth 

meas urement to which all instruments would be ca librated, resulting in a 

dependent ca libration. The second ca libration technique is most practical for 

ca l i brating large numbers of instruments s ince atmospheric conditi ons adequate 

f or good Langley ca l ibra tion ca n be rare. Howeve r, in application the dependent ca lib ration procedure requires the establis hment of a high-integrity 

reference instrument or in struments. Lacking suc h a reference instrument, the 

conse nsus of the intercomparison was chosen as an arbitrary reference for 

comp arison only. 

The principle conclusion of t he intercomp arison was that the establishment of a high-accuracy standard sunphotometer would permit sufficient 

quality network meas ureme nts to monitor ae rosol optical depths of the magnitude typically encountered in c l ean remote locations . 

4.13 The Phot ovoltaic Power System at StlO 

Work bega n on preparation of the phot ovo ltaic powe r system s pecifi ca tions 

at StlO after G~ICC was notified that funds were awarded by the Federal Photovoltaic Utilization Program of DOE in April 1980 . The system as defined in 

the request is to provide 1 kW of co ntinuous e l ec tri ca l power t o the StlO 

observatory. J. Jordan and G. Herbert prepared the specifications that 

subsequently became part of the request for proposal (RFP) . A source evaluation board (SEB) was selected a nd app roved in November 1980. The RFP was 

reviewed by the board and s ub sequently issued in ay 1981 (NOAA no. 34-81). 

The responses to the RFP were reviewed by t he SEB in July. All proposals were 

found to be non res ponsive because of te chnical difficiencies or excessive cost 

estimates. The three main reasons for the excessive cost estimates were 

(1) the request that the vendors supp l y all t he technical and manual labor for 

the transportation and installation of the photovoltaic arrays ; (2) problems 

with the purchase, trans portation, a nd hous ing of the batteries ; a nd (3) the 

absence of a ny spec ific limits on the physical s ize of the photovoltaic array . 

Studies of the variabl es that de termine the size of the photovoltaic 

array began with assembling StlO global insolation measurements into a data 

ba se of hourly average values from January 1976 through December 1979. All 

measurements were made with pyranometers ope ra t e d on hori zontal surfaces on 

the roof of the GHCC station at Cape Natatu la. J. Osborn, NOAA Corps, edited 

the data, prepa red t ab les of the daily available global solar e nergy , and 

pub lished t he tables with the RFP. The so lar energy at Cape Na tatul a is 

typical of that found on the windward side of tropical i slands: relatively 

clear morni ngs and cloudy afternoons . The meas urements do s how t he occurrence 

of prolonged periods of excessive c l oud i ness ; typically, periods of a week 

occur one or two times per yea r . In the 4 years of t he data set t he longest 

such period was 13 days. To build a system that would carry the load wi thout 

use o f i s l and power for this period would not be feasible. The effect of 

tilting the photovoltaic arrays was also evaluated by installing a pair of 

pyranometers on tiltable stands (fig. 56) and recording the data. One stand 

i s at a fixed tilt of 14°, the latitude of the s tation, the other is change d 

monthly from -10° to 35° . The ratio of dai l y insolation on the tilted surfa ce 

to the daily insola t ion on a horizontal surfa ce was averaged by month (tabl e 34) . For slightly more t han a year the maximum increase resulting from 

tilting is about 10% at 14° and 22% at 35°. Theoretical results (Jordan and 

102 
Figure 56.--Pyranometers on tilted 

stands on t he roof of the SMa 

observatory. 

Liu, 19 77) tend to overpredict the e nhancement. This is probably due to 

improper accounting for cloudiness. 

The values provided in the response to the RFP were used in programming 

and operating a simple computer mode l to determine t he overall performance of 

the system. So l ar irradiancc measurements were used as input to the model, a 

1-kW l oad was assigned, and efficiency factors were used as specifi ed in the 

proposals for individual components. The state of cha nge of the ba tteries was 

computed and the charging cycle initiated at the specified l eve l (usually 80% 

discharge) . Battery life is directly related to the number of deep-discharge 

cycles. IVhen t he batteries r each t he deep-discharge level t hey must be 

Table 34.--Monthly averaged ratios of the daily insolation 

on a tilted surface to that on a horizontal s urface 

Nonth 14° tilt 14° tilt , 

Jordan and Liu'·' 

Ja n 0.88 0 . 93 

Feb 0.91 0.97 

Mar 0.96 1. 06 

Apr M 1. 15 

~lay N 1. 22 

Jun 1. 09 1. 26 

Jul 1. 06 1.24 

Aug 1. 09 1.17 

Sep 1. 03 1. 08 

Oct 0.97 1. 00 

Nov 0.93 0.96 

Dec 0 . 91 0.91 

*Data extracted from Jordan and Liu (1977, fig . A-4). 

Note: M = missing data. 

103 

Variable 

tilt 

0.94 

0 .94 

0.96 

N 

M 

1. 22 

1. 10 

1. 14 

1. 03 

1 

0.99 

1. 00 
recharged from i s land power or the system must be shut down to avoid damaging 

the batteries. The model, written by R. Clark of GMCC, a l so computes the 

munber of hours the system is operated by solar power and the duration of 

fully charged periods . The resulLs of such studies provided the limit guidelines needed for the second issue of the RFP. 

The best information on photovoltaic batteries indicated that a reasonable life expectancy would be 8-10 years. The manu facturers specify the 

life in terms of 1,800 deep discharges but guarantee the unit for 800-1,000 

deep discharges. Sizing criteria were selected that would yield approximately 

100 deep dis charges per year. Thus, the photovoltaic array was limited to a 

size that would produce 6,000 W of electrical e nergy at incident radiation of 

I kW m- z . The capacity of the batteries was spec ified to carry the load of 

the system f or not less than two consecutive sunless days. With such limits 

impos e d in the second issue of the RFP (no . 54-81), i ssued in September 1981, 

the responses were, for the most part, technically acceptabl e and within the 

budget. The source evaluation board met in Decemb er 1981 and, after questioning the responders , agreed to make an award to Solarex Corp., Rockville, Md. 

The photovoltaic array will be l ocated on t he southern end and along part 

of the eastern side of the observatory. The array will consist of 100 modules 

grouped in 5 subarrays, each approximately 15 mZ in area. The total area of 

the array is therefore about 75 m2 . The subarrays will be positioned on tiltable stands (-10° to 35°) at a height of 3 . 7 m. The batteries will consist of 

10 units to be wired in series and to be positioned along the south wall of 

the data room. The ventilation in th is room will be increased to remove 

excessive hydrogen. The system controller, inverter, and battery charger will 

be located next to the batteries. GMCC staff will consLrucL a monitoring 

system to measure the voltage on the direct current bus, the current at 

different points in the system , and the power delivered by the system. These 

measurements will be used in conjunction with the computer model to monitor 

the efficiency of the system as a function of time. 

104 
5. COOPERATIVE PROGRNlS 

5.1 Ultraviolet Erythema Global Measuring Network 

D. Berger 

Skin and Cancer Hospital, Temple Universi ty 

Philadelphia, PA 19140 

A global network of meters recording the sunb urning (erythema) effect of 

solar ultraviolet radiation has been providing data since 1973. The nwnber of 

stations continues to increase; 30 stations now report regu larly and 2 more 

stations are expected to start functioning nex t year . 

The sunburning effect of ultraviolet radiation is proportional to a number of other effects that this most energetic part of the solar spectrum can 

produce in biota, such as DNA damage, human skin ca ncer , tobacco leaf spotting, reduced viability of shallow-laid fish eggs, and the induction of vitamin D formation. 

A report based on results from 14 of the longest operating stations was 

published by Berger and Urbach (1982). A list of all stations appeared in the 

GMCC Summary Report for 1979 (Herbert, 1980, p. 100); two additional stations 

to be added to that list are La Jolla, Calif., online since Ap ril 1979, and 

Invercargill, New Zealand, in operation since July 1981 . Data for this network are distributed by NOAA/ARL, 6010 Executive Blvd., Rockville, ~ID 20852. 

5.2 NO Measurements at MLO 

x 

J . F. Noxo n 

Aeronomy Laboratory 

NOAA/ERL, Boulder, CO 80303 

Spectra of radiation emitted by the rising a nd setting sun have been measured at MLO to determine NO (NO + N0 2 ) in the free troposphere at -3-km altitude (Noxon, 1981). Very ~w values were found for the mixing ratio (30 ± 

10 pptv). Comparing these res ults with earlier measurements made by others at 

the sea surface in the mid-Pacific, one may infer that the source of the NO 

is almost certainly natural and must be located in the upper troposphere. x 

However, some may also come from t he stratosphere . Such l ow values for NO 

suggest that photochemical production of ozone is small in most of the rem~te 

marine lower troposphere. 

N03 was also measured in both the troposphere a nd stratosphere at flLO 

using the moon as the light source (NO! is onl y present at night). The results show that stratospheric N03 behaves quite differently at low latitudes 

than at middle and high latitudes. At MLO the behavior is in agreement with 

the chemistry presently thought to govern nitrogen oxides in the stratosphere; 

at higher latitudes the behavior is not as expected, NO! being almost always 

far less than predicted. 

The measurements of tropospheric NO! at flLO show that ·it is efficiently 

scavenged by a species as yet unknown. It appears that scavenging proceeds at 

about the same rate as it does in clean continental air. The sign{ficance of 

this scavenging to tropospheric chemistry rema ins unclear; it is not yet known 

whether or not the scavenging process corresponds to a sink for odd nitrogen. 

This program of measurements 1S expected to continue. 

105 
5.3 On the Re lationship Between Surface Air Temp erature and 

Concentration of Pollution-Derived Elements at BRW 

W. E. Raatz 

Geophysical Institute, University of Alaska 

Fairbanks, AK 99708 

Pronounced, repeatable seasonal variations of noncrustal vanadium, noncrustal manganese, and nonmarine sulfate as well as fluctuations on s horter 

time scales (days to weeks) have been observed (Ra hn and ~!cCaffrey, 1980; 

DeLuisi , 198 1, p. 11 3). The research intention of this study is to explain 

these variations in terms of the meteorological conditions both at the sampling site and along the different transport pathways from the suspected 

source areas in midlatitudes. Her e , we discuss the relationship between air 

temperature at BRW and noncrustal (pollution-derived) vanadi um concentrations. 

On the basis of data for four winters (October-April), the correlation 

coefficient of monthly averaged noncrustal vanadium concentrations and temperature was calculated to be r = -0.8. Cold temperatures are associated wi th 

hi gh conce ntrations of noncrustal vanadium. Highest concentrations of noncru s t a l vanad ium are usually found during ~larch; a secondary maximum appears 

to be present during Decemb er (Rahn and ~!cCaffrey, 1980). February is the 

coldest month at BRW, on the basis of a long-term average, but conditions can 

differ significantly during individual years . Wilson (1969) noted that temperature variations in the Arctic during winter conditions are mainly determined by fluctuations of the large-sca le circulation patterns and associated 

storm tra c ks, and that changes frcln one persistent circulation pattern to 

another can be rapid. Thus, monthly mean values can be misleading, and it 

would be of interest to see how noncru~Lal vanadium concentrations and temperature correlate on time scales s horter than 1 month. In fact, correlation 

be tween daily noncrustal vanadium and daily mean temperature for December 

1979-April 1980 provided a correlation coefficient of only r = -0.1. Thus, 

they correlate on long seasonal time scales, but the correlation disappears 

when the time series contains shorter frequencies. 

To und erstand t he breakdown of the correlation between noncrustal vanadium and temperature on s hort time scales, note that during March 1978 severa l 

inj ections of pollution aerosol had originated in Europe (based on the Mn/V 

ratio , Rahn, 198 1), but arrived at BRW in air masses with differing temperatures as a res ult of modifications of the air masses associated with different 

paths and transport times. Thus, air masses arriving at BRW were similar according to their chemi cal characteristics but different according to their 

temperatures. Apparently, on short time scales, the variation of noncrustal 

vanadium is source related, whereas the variation in temperature is more dependent on transport pathways. Thus, an air ma ss can undergo considerable 

meteorological modification, yet still retain a memory of its earlier passage 

over pollution sources . 

Spectral analysis of the daily temperature time series revealed a characteristic period of 18-20 days. The nonc rustal vanadium also showed a period 

of 18-20 days, but in addition, there was a second period of 7 days, not seen 

in t he temperature data. The characteristic period of 18-20 days is assume d 

to be associated with large-s cale circulation patterns (McGuirk and Reiter, 

19 76) . The causes for the 7-day period found in the noncrustal vanadium time 

seri es have not been confirmed. It is likely to be related to mesoscale 

synoptic systems traveling in the Arctic; if so, the chemical fingerprint of 

traveling air masses is preserved longer than the meteorological one. 

106 
5.4 Atmospheric 210Pb at BRW and tILO 

H. W. Feely and C. G. Sanderson 

Environmental tIeasurements Laboratory 

u.S. Department of Energy, New York, NY 10014 

High-volume filter samplers are operated for EtIL at each of the four GtICC 

observatories. These are part of a network of about 20 samplers that are operated for EtIL, mainly i n the Western Hemisphere. tIonthly composites of the 

filter samples are analyzed routinely by gamma spectrometry for 7Be, 95ZR , 

137Cs, and 144Ce. During mid-1974 to mid-1976 these filters were also 

routinely analyzed radiochemically for several radionuclides, i ncl uding 21Dpb. 

It was noted that the concentration of 21Dpb in air appeared to reach a 

maximum i n the winter at BRW and in the sp ring at tILD. Subsequently K. Rahn 

of URI pointed out that the high 21QPb concentrations at BRW appeared to 

coincide with the influx of polluted air from midlatitudes, which produced t he 

wintertime Arctic ha ze layer. He s uggested that 222Rn emitted from the 

deserts of Asia might be the source of this 2 1Dpb. Similarly, the 21Dpb 

maximum in air at HLO coincides with the arrival of dust from the Asian 

continent during the spri ng. 

To verify the apparent seaso na l variations in 2 1UPb concentrations , samples collected during 1977, 1980,and 1981 at BRW and during 1980 and 1981 at 

HLD have now been a na l yzed for 210Pb using gamma spectrometry . As shown in 

fig. 57 the new data co nfirm the seasonal variations shown by the older data. 

Beginning in December 1981 some quasi-wee kly samples from BRW and MLO are 

30 P 

0 

~ 25 :J I) <> 

~ • 

" I) 

'" 20 • \ " 

~ 

" 

~ 15 A 

"' • • :s 

" ~ 10 

~ '" ~ 

~ 5 

<§ 

" 

~ 

~ 15 ~ 

0 ~ • " 10 

t: 

5~ 

J F M A 

BARROW 

o 1974 -1976 

~ 1977 

C 1980 

.1981 

,~ 

• Cl 

g, '- ""' • 

MAUNA LOA 

0 c 

0 

c, 

,... ;: 

0 [] :: :: R 

M J J A S 0 

;, 

~ 

~ 

C C 

N 0 

Figure 57.--Honthly concentrations of 

210Pb in surface air at BRW (top) and 

mo (bottom). 

107 
being analyzed for 210Pb by gamma spectrome try to provide finer resolution of 

the times of arriva l of high concentrations of 210Pb at these stations. 

5 .5 Air Chemistry Monitoring at Pa l mer Sta tion 

E. Robinson and W. L. Bamesberger 

Air Pollution Research Section, Col l ege of Engineering 

Washington State University, Pullman, WA 99164 

The obj ec tives of this resear ch p rog ram are to measur e continuously the 

trace chemical constituents of the atmosphere at Palmer Station, Antarctica, 

and to relate findi ngs to me teo rol ogical conditions. The meteorological correlations will be sought on the ba sis of regional synoptic weather patterns 

and more general seasonal meteorol ogical conditi ons . The air sampling facility was named the Anvers Island Air Chemistry Facility at the station dedication on 16 January 1982 by F. Williamson . The Palmer air chemistry station 

ha s been equipped to measure on a regular or continuous basis the trace atmospheric parameters listed in table 35 . The frequency of measurement and the 

methods used are also listed. 

The air sampling facility i s a separate building wi th a 10- x 14-ft nominal floor space plus a 4- x 4-ft doubl e -door entry vestibule for wind and 

weather protection . The station was prefabricated and then erected in a preliminary fashion at WSU at which time the sampling instruments were set up and 

checked. The air chemistry station is l ocated east of the main Palmer Station 

Table 35.--Trace atmo spheric parameters a nd method s of mea s urement 

used at the Anvers Island Air Chemistry Facility* 

Comp onent 

Methane (CH.) 

Carbon dioxide (C02 ) 

Carbon monoxide (CO) 

CC1 3 F (CFC-l1) 

CC1 2F2 (CFC-1 2) 

Carbon tetrachloride (CCI.) 

Methylchloroform (CH3CC1 3 ) 

Nitrous oxide (N 2 0 ) 

Aitken nuclei 

Frequency 

Continuous 

1 h- 1 

1 h- 1 

1 h- 1 

1 h- 1 

1 h- 1 

Continuous 

Method 

UV photometer: Dasibi 

Automatic gas 

chroma tograph: 

Carle Mode l 211 

Automatic dual-channel 

gas ch romatograph: 

Hewlett-Packard 

Nodel 5880 

Expansion-type 

photometric system: 

Environment One 

*The designation Anvers Is l a nd Air Chemistry Facility was given to the 

Palmer Station facility at its dedication 16 January 1982 . 

108 
building complex, about 150 ft east of the old helicopter pad . Power for instrument operation and heat comes from the Palmer generating plant through a 

l and line . A 5-cm-diameter stainless steel air inlet stack extending about 

3 m above the building and leading to a connecti ng manifold inside is flushed 

by a small blower to provide a clean-air source for the sampling instruments. 

The system including the computer-controlled data system was fully operat ional on 15 February 1982. All instrument outputs are recorded by a HewlettPackard 85 data system that also provides the cyclic control signals for the 

gas c hromatographs. Strip charts provide backup for the HP 85 computer syst em. The instruments are standardized against gas mixtures that were calib rated against known standards prior to shipment to Palmer. Long-term sta nda rds are maintained at WSU. The CO 2 data will be standardized through crosschecks with the GMCC program. Weather data will be included in the data file 

by manually transcribing the observations from the Palmer station records. 

Recorded wind data and the response of the CNC will be used to identify periods when emanations from the Palmer activities may be affecting the sampling 

r es ults. Available wind records indicate that flow from the west, which would 

r esult in contamination by effluents from the main station, i s not a predominant wind direction. 

The Anvers Island Chemistry Facility is expected to operate for a period 

of 4-5 years. Measurements made at the facility can be expanded as new instrume nts adaptable to the rugged Palmer environment and low background l evels 

become available. The sampling results are expected t o complement GMCC air 

sampling data collected at SPO and SMO, as well as data gathered at the 

Australian background station at Cape Grim, Tasmania. The particular interest 

of t he WSU program is the interaction between air chemistry patterns and synoptic weather situations. Personnel at the air chemistry fa ci lity expose one 

pair of flasks each week for subsequent CO 2 analysis by G~lCC. The facility 

ca n also provide support for other research investigators interested in air 

chemistry and related studies. 

Ac knowledgment 

This research was supported by NSF under grant no. DDPP-8005797. 

5.6 SEAREX Atmospheric Chemistry Studies at S~10 

B. J. Ray and R. A. Duce 

Graduate School of Oceanography, University of Rhode Island 

Kingston, RI 02881 

5.6. 1 The SEAREX Program 

SEAREX, supported by NSF, is a coordinated multi-institutional cooperative research program involving 11 laboratories investigating the atmospheric 

t ransport of both anthropogenic and natural trace substances to marine areas. 

The objectives of this program are (1) the quantitative mea surement of the 

Pacific Ocean air-sea exchange of selected heavy metals and other trace elements, soil dust, 210Pb and 210pO, sulfate, nitrate, particulate organic carbon, and organic compounds, primarily PCB, DDT, aliphatic hydrocarbons, 

phthalate plasticizers, fatty acids, polycylic alcohols, and low-molecularweight ketones and aldehydes; (2) the identification of the sources of these 

109 
substances in the marine atmosphere over the Pacific Ocea n; and (3) the identification of mechanisms of exchange of these substances across the sea-air 

int e rface. 

Sin ce more than 90% of global atmospheric pollutants are i njected into 

the Northern Hemisphere and since the tropospheric residence times of atmo spheric particles are relatively short (days to 12 weeks) compared with re latively l ong (6 months to 2 years) tropospheric mixing times between the 

Northern a nd Southern Hemispheres (Junge, 1963; Duce et al., 1974; Newell e t 

a l. , 1974), significant differences may be observed for anthropogenic substances present on atmospheric particles and certain trace gases at remote 

areas in the two hemispheres. Therefore, major differences in atmospheric 

conce ntration or deposition at these sites may be related to anthropogenic 

sources. Islands chosen as atmospheric sampling locations must necessarily be 

thousands of miles from continents and in strong trade wind or westerly r egimes, thereby exhibiting nearly ideal atmospheric conditions. In addition 

they should be free of large sources of l oca l anthropogenic inputs. SEAREX 

ha s chosen four regions of the Pacific that conform to these criteria. Experiments have or will be conducted on (1) Bokandretok Island, Enewetak Atoll, 

Mars hal l Islands (Northern Hemisphere trades, April-May and July-August 1979); 

(2) Cape Matatula, Tutuila Island, American Samoa (Southern Hemisphere trades, 

January-February and July-August 1981); (3) Ninety Mile Beach, North Island, 

New Zea land (Southern Hemisphere westerlies, June-August 1983); and (4) a 

cruise track north of the Hawaiian Islands at about 40°-50° latitude (Northern 

Hemisphere westerlies, July-August 1985). See DeLuisi (1981, pp. 11 6-117). 

In April 1980 atmospheric tracer studies using sulfur hexafluoride (SFs ) 

were carried out at SMO to investigate the possibility of contamination due to 

eddying effects around the local topography and due to the small island of 

Aunu ' u, as well as the passage of ship s (Reible et al., 1982). Results of 

these studies were reported in DeLuisi (1981, pp . 118-121). 

As a result of these preliminary studies, two aluminum-scaffold walk-up 

t owers were erected on the eastward edge of the tip of Cape ~Iatatula. An 18-m 

walk-up tower was used for the collection of all the atmospheric samples as 

well as for organi c and nutrient rain collections. A 13-m walk-up tower was 

us ed for the collection of trace-element rain samp le s as well as for traceelement and organi c dry-deposition samples . In addition to the towers, several buildings were erected at the site. Tqe existing building erected a t the 

ba se of t he air tower in 1976 by URI was used for monitoring the meteorologica l and electronic status of the experiments. New buildings were constructed 

t o house the organic and trace-element laboratories as wel l as to provide 

space for recreation, storage, and protection of t he electrica l transformers. 

An additi ona l modular building was positioned at the top of the stairs to 

house a laboratory for analysis of pH, conductivity, and nutrient s in rain. 

The construction phase was completed in August 1980. 

SEAREX pers onnel returned in December 1980 to prepare for the experimental phase. Meteorological equipment for monitoring wi nd speed and direction, eN concentration, relative humidity, and rainfall were installed on the 

atmospheric sampling tower. Data from these sensors were fed into a contro l 

system that turned the air samplers on when the winds were from a preset oceanic sector (0°-145°) and CN counts were low, thus avoiding local island contamination e f fects . The site was manned 24 h day-l during the experiment. 

The meteorological data were stored in a microcomputer that also monitored the 

110 
operational st atus of th e various sampling syst ems . A Furuno weather radar 

was invaluable in predicting the onset of precipitation, espec ially at night, 

and the app r oach of vessels . Samp ling on the tower was stopped when s hips 

passed through the Clea n Air Secto r. 

As many as 36 different samp ling systems were operati ng on t he tower for 

the collec tion of trace e lements, sea sa lt, organi c substa nces , and nutri ents . 

At any time each research group could e le ct to sample in any or all of three 

different mod es : (I) ISS (inside selected sector)--sampling occ urri ng in the 

clean air sector; (2) OSS (outside selec ted sector) --sampl i ng occurring from 

the island (local contami nation) dire c tion and/or conditions of high CN 

counts; and (3) manual - -sampl ing occurring fr om a ll wind directions and irrespective of CN counts. Rain was sampled on an event basis. Frequently as 

many as six different precipitation samplers were i n use simultaneo usly. To 

avoid contamination of the samples, grea t care was t aken in the fabrication, 

pre para tion, and use of both t he precipitation and atmosp heric sampl ers and in 

the ana lytical procedures. Numerou s sampling and handling blanks were co l -

le cted and processed simultaneously with the samples as a further assessment 

of potential contaminati on . Samplers were also operated at ground l eve l to 

investigate loca l vegetatio n and soil sources of contaminatio n f or organics 

and trace e l ements. 

The sampling periods at Stl0 were January-February and J uly-August 1981, 

the local wet a nd dry seasons. During the first period rainfall was 36 . 8 cm, 

whereas during the second period it dropped to 11 . 2 cm. In addition to the 

Cape Ma tatul a wor k, sea water samples we r e collected, about 4 mi offs hore fr om 

a u.S. Coast Guard ship, for c hemica l analysis. Sixteen scientists participated in each of the SEAREX Samoa experiments. 

5.6 .2 Analytical Res ults 

Althou gh many analyses are still in progress , some preliminary data are 

avai lab le on the chemi cal compo sition of the aeroso l, trace gas, and precipitation samples collected at SMO. 

Rain pH and Ma j or I on tleas urements 

Precipitation measurements were made by t he URI during both experiments 

t o determine the major ion conten t and pH of Samoan rain. Collection of the 

samples was made in a ca refully cleaned polyethylene rain sampl er . As soon as 

po ssible a fter co l lection, pH was measured, and within - 72 hours of co llec-

+ - - = + --" . tion, Na , Cl , N03 , S04 , NH4 ) NO z , F , and P0 4 \vere measured U S1 0 g a 

Dionex mode l 16 ion c hromatograph. The rain was slightly acid ic relative t o 

an equilibrium sol ution of distilled wate r and atmospheric C02 . For rain 

samples be l ow 0 .01% 0 salinity t he mea n pH was 5 .52 (range: 5 . 33-5.98) . For 

ra i n sample s with sa linity higher than 0 . 01 % 0 , t he pH ~as sl ightl y higher, 

with a mean of 5 . 80 (range: 5.53-6.57) . The average N0 3 concentration was 

0.2 eq kg-I, and the non-seasalt (or excess) s ulfate from 

= + = + 

(SO'-)excess = (SO. ) total - (Na ) x (SO. /Na )seawater 

was 1 . 5 q kg-I. Model ca l culations indi cated that this nitrate a nd s ulfate , 

if present as the strong acids HN0 3 and H2S04, could lower the pH to the va lues observed (Pszenny et al. , 1982 ). The concentrations of other anions in 

111 
the rain 

and P04 -

analyses 

+ 

were found to be NH4 $ 

~ I ~g £-, (Pszenny and 

are still in progress. 

Chlorinated Hydrocarbons 

20 ~g 

Duce, 

£-'; N03 ~ 5 ~g £ '; F ~ 5 ~g £ '; 

1981). Alkali and alkaline earth metal 

Investigators from Texas A & ~1 University have analyzed the S~10 samples 

for heavy chlorinated hydrocarbons. They found concentrations to be 210 times 

lower at S~10 than at the Northern Hemisphere sampling site at Enewetak. They 

found about 99% of the chlorinated hydrocarbons were present in the vapor 

phase with % i n the particu late fraction . The mean concentrations observed 

were pentachlorobenzene, ~9 pg m- 3 ; hexa chlorobenzene, 55 pg m- 3 ; hexachlorocyclohexane, 30 pg m-3ilindane (dry season), 1.5 pg m- 3 ; PCB, 12 pg m- 3 ; ~DDT 

(dry season), 1 .5 pg m 3; dieldrin (dry season), 2 pg m- 3 ; and chlordane (dry 

season), <1 pg m- 3 !Giam and At las, 1982) . These values are similar to values 

found by these investigators in the atmosp here over the upwelling waters off 

the coast of Peru. Rain concentrations of these substances at SMO were approximately an order of magnitude less than in Enewetak, but similar washout 

factors were observed . Concentrations o! some of these subs!ances in rain at 

SMO were hexachlorocyclohexane, 390 pg £ '; lindane, 33 pg £ '; PCB (1254), 

~200 pg £-'; ~DT, 17 pg £-'; dieldrin, <30 pg £-'; and chlordane, <30 pg £-, 

(Giam and Atlas, 1982). 

During the wet season, oceanic air from the Clean Air Sector was found to 

have - 0.01 ng m- 3 DDT whereas air that had passed over Samoa contained much 

higher DDT levels, - 1 ng m- 3 , a concentration higher than that found at a sampling site in College Station, Tex. Similarly, the wet-season oceanic air was 

found to contain the (~C'5-C28) n-alkanes at a mean total concentration of 

3 .9 ng m- 3 while local island air averaged 28 ng m- 3 (Giam and Atlas, 1981). 

These examples illustrate the potential problems of local contamination unless 

extreme care is taken during sample collection. 

Particulate Trace Elements and Salt 

Duce et al. (1982) have completed some analyses for trace elements in the 

aerosol samples from SMO . The concentrations for some elements are among the 

lowest ever reported near the Earth's surface. The preliminary concentrations . -3 . -3 -3 

are a lumInum, 0.2-0.5 n8 m ; Iron, 0 .15-0 . 22 ng m ; lead, 0.02-0. 03 ng m ; 

selenium, 0.05-0.1 ng m 3; dust, 2-7 ng m- 3 ; and sea salt, 6-12 ~g m- 3 . 

On the basis of the analyses complete d to date, the trace metals have 

similar concentrations during both sampling periods. Great care was taken to 

avoid contamination during the collection and analysis of these samp l es. Filters and filter holders as well as sample storage bags were all polyethylene 

and were acid-cleaned. A large number of handling and towe r blanks were processed with all the samples, and all samp l e handling occurred in a clean room 

or clean bench. All personnel wore clean-room garb and gloves while handling 

the samples both on the tower and in the laboratory. The concentrations observed at SMO for many trace elements were 310 times lower than Northern Hemisphe re concentrations observed by SEAREX at Enewetak. 

Lead analysis of samples collected by personnel from URI and California 

Institute of Technology resulted in similar concentrations. The samples were 

11 2 
collected independently and utilized different collection and analytical procedures. For the January-February experiment, Patterson and Settle (1981, 

1982) report rain concentrations for lead of 9-13 ng kg-I, lead dry-deposition 

rates of 2.4 ng cm- 2 yr- l , aerosol concentrations o f 0.04 ng m-a, and surface 

seawater concentra t ions of 3 .5 ng kg- 1 Dry-season measur ements are still in 

progress. 

A comparison of the a tmosphe ric concentration of several trace elements 

was made between sampl es collec ted from the oceanic clean air sec tor (ISS) and 

those from OSS, i.e., susceptible to loca l island contamination eDuce et aI" 

1982) . A comparison of two sample se t s is s hown i n table 36 . 

Table 36.--Compa rison of I SS vs. OSS tra c e element 

concentrations at S~ O 

Collection Trace Element Concent rati on 

period Al Fe Pb Se Na 

(1981 ) (ng m-") (ng m- 3 ) (ng m- 3 ) (ng m - 3) (~ g m - 3) 

16 Jan-8 Feb 

ISS 0 . 25 ± 0.05 0 . 15 ± 0 . 04 0.020 ± 0.008 0.058 ± 0.008 1. 7 ± 0 . 2 

OS 5;·' 1 . 3 ± 0.2 1. 6 ± 0.3 0. 100 ± 0.030 0.073 ± 0.009 5 .0 ± 0.5 

9 Feb-25 Feb 

ISS <0. 5 0 . 22 ± o. 13 0.025 ± 0 . 010 0 .0 70 ± 0 .0lD 2.4 ± 0 . 3 

OSS;·, 4.9 ± 0.5 5 .1 ± 0 . 6 0.110 ± 0.020 0.093 ± 0 . 010 6.0 ± 1.0 

~'{Local contamination i s clea rly apparent for AI, Fe, Pb, and · Na under OSS 

conditions. 

Measurements by Ya le University of 2l0Pb in the aerosol indicate that 

oceanic (ISS) air contained 1 .6-2.1 dpm ( 103 m3)-1 while island air (OSS) contained 3.5 dpm (10 3 m3)- 1 for the January-February samples. Turekian et a l . 

(1982) suggest that a lo ca l island source f or that much 2l0Pb is unlikely and 

postulate tha t the excess may come from the intrusion of high 2l0pb air from 

above the trade wind inver sion. 

Additiona l analyses are s till in progress for the trace gas, aerosol, 

precipitation, dry-deposition, and sea water sampl es collected at SMO in 1981. 

Upon compl etion of the SEAREX experiment at the end of August 1981, the 

SEAREX sampling towers were removed from the Cape Matatula site and forwarded 

to New Zealand for the nex t SEAREX experiment. Sampling gear and meteorologi ca l sensors were re turned to the United States for refurbishing. One small 

wooden building was removed from the site, but other buildings, which were in 

good condition, were left at SMO . A 9-m tower for us e by GMCC was erected on 

the site of the atmospheric sampling tower. 

113 
Acknowledgment 

SEAREX personnel wis h to exp ress their appreciation to the GfICC staff for 

their s upport and assistance. In particular we wish to thank the personnel of 

the G~ICC SNO station: R. Williams, E. Peau, a nd especially t he Station Chi ef, 

D. Nelson, whose continued patience , coopera tion , and assist ance guara ntee d 

the s uc cess ful completi on of the SEAREX experiments. 

5.7 Atmospheric Trace Gases a nd Arctic Haze at BRW 

R. A. Rasmussen a nd N. A. K. Khalil 

Oregon Graduate Center 

Beaverton, OR 97006 

For several decades a winter haze has appeared in the Arctic, thousands 

of mil es from the neare st area of de nse human population or maj or industrial 

activity . Yet there is considerable evidence that this submicron-sized ha ze 

aerosol consisting of sulfate , soot, and organics results from human ac tivities (Rahn and ~lcCaffrey, 1980; Wes chle r, 1981; Rosen et a1., 1981). The 

small ratios of primary to secondary components, the presence of combus tionderived soot and va nadium, and the presence of excessive amounts of anthropogenic gases all attest to the distant origins of Arctic haze (Rosen et al ., 

1981; Rahn and He idam, 1981; Ottar, 1981; Husar and Patterson, 1979; Ra hn and 

NcCaff rey, 1980; Shaw, 1981; Khalil a nd Ra smussen, 1982). Although current 

knowl edge favo r s Eurasia as the domin ant source, significant cont ributions 

from other indu stria li zed and populated areas, including the United States, 

cannot be ruleo out (Rahn, 1981c; Barrie et a1., 1981; Reiter, 1981). Except 

f or a consen sus that the presence of soot ca n heat the lower atmosphere of the 

Arctic , the possible environmental effec ts of continued or increased Arctic 

air pollution have yet to be worked out. See also Borys and Rahn (1981), Ra hn 

(1981a), Rahn and Heidam (198 1), and Rosen e t al. (1981). 

It is r easo nable that ma ny e xotic trace gases that are produced at the 

same midlatitude regions of the Northern Hemisphere as the precursors of 

Arctic haze will a lso be transported to the Arctic. Sil ch inert gaseous 

tracers can be used to identify the origins of Arctic haze in mu ch the same 

way as the ratios of elemental tra ce rs (Rahn, 198 1b). 

In this pap er data are reported on eight potential anth ropogenic gaseous 

tracers of Arcti c haze, namely CFC-ll (CC1 3F), CFC- 12 (CC1 2F2 ), CFC-22 

(CHC1F 2 ), methyl chloro form (CH 3CC 1 3 ) , perchloroethylene (C 2C14 ) , trichloroethylene (C 2HC1 3 ), carbon monoxide (CO), and methyl chloride (CH 3Cl) . The 

criteria for a gas to be a tracer of Arc tic pollution are discussed, and 

finally conclusions that ca n be drawn from the trace gas studi es are reviewed. 

Furthe r details of most topics discussed here are presented in the pa per of 

Khalil and Rasmussen ( 1982) . 

5.7.1 Data a nd Analysis 

Since Augu st 1980 s amples of Arctic air have been collected by GNCC at 

BRW. Each week three samples are co llected , one immediately after the other, 

in s pecia lly prepared, internally S~~-poli shed, stainless st eel 0 . 8-Q 

fla s ks. An ultra clean Ne t a l Bellows NB-15 8 pump is used to fill the flasks. 

114 
Table 37 . --BRW monthly ave.aged conc ent.ati ons of 

anth.opogenic haloca.bons, a nd CH 3Cl and CO 

Hooth CHClF 2 CCI 2F2 CCl 3 F CH3 CCI 3 C2Cl, C2 HCI 3 CH 3 CI CO 

1980 

8 65 (4) 321 (12) 192 (5 ) 155 (4) 545 (51 ) 96 (5 ) 

9 66 ( I ) 327 (4 ) 192 (4 ) ISS (3) 542 (40) 10 7 (5 ) 

10 66 ( I ) 331 (3) 194 (2) 159 (3) 542 (40) 96 (11 ) 

I I 68 (2 ) 332 ( I ) 195 (1) 162 (5) 561 (13) 113 (11) 

12 71 (6) 336 (4) 195 (4) 171 (1 8) 581 ( 11) 153 (2 1) 

1981 

1 81 (3) 334 (3) 193 (2) 185 (17) 627 (34) 149 (18) 

2 69 (1) 337 (5 ) 147 (8) 166 (6) 145 (6) 51 ( - ) 608 (15 ) 174 (27) 

3 67 (2) 333 (4) 198 (1) 167 (2) 106 (7) 15 (14 ) 623 (15 ) 157 (10) 

4 69 ( I ) 331 (5 ) 199 (1) 166 (2) 104 (8) 12 (9) 623 (7) 160 (1 3) 

5 69 (1) 336 (1) 200 ( I ) 167 (2) 74 (13) 9 (-) 639 (21 ) 146 (12) 

6 69 (I) 335 (6) 200 (2) 165 (4) 74 (3) 6 ( - ) 621 (38) 106 (12) 

7 69 (2) 337 (6) 200 (2) 162 (1 ) 62 (3) 4 (2) 565 (33) 78 (6) 

8 70 (I) 340 (2 ) 199 (2) 162 (3) 62 (3) 8 (2) 541 (28) 70 (9 ) 

9 71 (I) 338 (4) 198 (1) 168 (6) 56 (3) 6 (3) 506 (40) 83 (4 ) 

10 71 (4) 345 (3) 197 (1) 166 (2) 75 ( - ) 1 I (-) 536 (14) 107 (9) 

11 73 ( 14) 348 (4) 200 (3) 189 (71 ) 587 (0) 123 (5) 

12 79 (10) 349 (1) 204 (1) 182 (25) 106 (20) 34 (20) 587 (10 ) 116 (27) 

19 82 

I 75 (3) 350 (3) 205 (1) 181 (16) 111 (10) 31 (9 ) 583 (5 ) 146 (78) 

2 77 (1) 354 (2 ) 208 (3) 176 (9) 120 (8) 37 (4) 646 ( - ) 183 (8) 

3 77 ( - ) 354 ( - ) 205 ( -) 177 (-) 

Note: Concentrations are in pptv excep t CO, \o.'hich are in ppbv. ( ) ~ 90% confidence 

limit s based o n the t-statistic. 

This equipment was designed and supplied by OGC. The samples a . e sent by ai. 

to OGC where they are analyzed, usually within a week after being collected. 

Well-established gas ch.omatog.aphy tec hniques a.e used fo. the a nalyse s as 

desc.ibed in ea.l ie. papers (Rasmusse n and Khalil, 1980; Rasmussen et al., 

1982). Each flask is analyzed twice, thus providi ng six de t erminati ons of 

each trace gas every week. In related la bo.a to.y studies i t ha s been established that the measu.ed trace gases a.e ine.t in the sampling fl asks fo. pe-

.iods of many months . The p.ecision of ana l ysis of the haloca.bons is <1% and 

fo. othe. gases, <5%. In all, the .esults of analyzing about 240 sampl es a.e 

.epo.ted he.e, constituting about 80 di ff e.ent sets of sampl es and spanning 

over 1~ years. 

As discussed earlier, the concentrations of six anthropogenic halocarbons, of CO, and of CH 3Cl we.e highe. du.ing winte. than in othe. seasons. 

Thei. monthly ave.aged concent.ations a.e listed in table 37 along with 90% 

confidence l i mits of the means . 

The data fo. CFC-II, -12, and -22, a nd f o. CH3CC l 3 we.e analyzed by first 

subtracting the annual trends of atmospheric concent ra ti ons according to the 

following fo.mula: 

115 
bt. 'k lJ 

where C = concentration (pptv); ijk is a time index with i = week (1, 2, 3, 

4), j = month (1, . . . , 12), and k = year (I, 2, 3); b is the slope of the 

annual trend; and t is time. For example, tIll is August 1980, when data were 

first obtained. These monthly averages with the trend subtracted were used to 

construct fig. 58, which shows higher concentrations of these gases in winter 

than in other seasons . After the trend was subtracted, data for the s ame 

month but different years were pooled together by forming the average 

C._,_ = (lIN) L' k C. 'k-'" where N is the number of data points for that month . J" 1 lJ" 

These data were analyzed statistically, and the results were r eported in detail by Khalil and Rasmussen (1982). The largest difference between s uch 

monthly means (6"') is given in table 38 along with other calculations based on 

the data. 

The cases of CH3Cl and CO are further complicated by natural sea s onal 

cycles in their concentrations. Still, when the concentrations found at BRW 

were compared with extensive meas urements made at Cape Heares, Ore, (45°N) , it 

turned out that large excesses of these gases were present at the Arcti c s ite 

only during winter. These tracers are i mportant because they are rel eased 

from specific combustion processes and coul d therefore aid in identifying the 

origins of Arctic air ma sses when the haze is present (Rasmussen et al., 1980; 

Crutzen et al., 1979; Rasmussen et aI" 1982; Khalil and Rasmussen, 1981). 

Table 38.--Comparison of the highest and lowest monthly 

concentrations of the Arctic haze tracers 

Gas ~tonths of cone. C (± OCma) C min (± 6Cmi n ) 6;'; (± 66';; ) 6;' ( ± 66;') 

Nax. Nin. max (%) 

CHCIF, (pptv) Jan Jul 62.5 (± 3.9) 55.3 (± 0.9) 7 .2 (± 3.9) 13 0 (± 7) 

CH 3 CC1 3 (pptv) Jan Jul 172. I (± II. 2) 149.7 (± I. 0) 22 .4 (± II. 2) 15.0 (± 7) 

CzC14 (pptv) reb Sep 128.0 (± II ) 56.0 (± 3) 72 0 (± I I ) 129 . 0 (± 20 ) 

CzHC1 3 (pptv) Mar Jul 40.0 (± 7) 4.0 (± 2.5) 34 0 (± 7) 850 . 0 (± 480) 

CC1 2Fz (pptv) Dec Jun 326. 7 (± 1.7) 318.7 (± 4.6) 8.0 (± 4.7) 2 . 5 (± I ) 

CClor (pptv) reb Jut 202.6 (± 3.4) 192. 3 (± 2. I) 10 3 (± 3 .7) 5 . 4 (± 2) 

CO (ppbv) reb Jul 179.0 (± II) 78 0 (± 7) 101 .0 (± II ) 130 . 0 (± 18) 

CH3Ct (pptv) Mar Se p 623.0 (± 19 ) 523 0 (± 22) 100 0 (± 24 ) 19.0 (± 5) 

Note : C max' C 

min are the average monthly highest and lowest concentrations during the year . 6e 

are the 90% confidence limits of C. 6;'; = (Cmax - e

min ) , and ± 60-;'- = 90% confidence 1 imi t s of 

6':;. 6;'; > 0 at CI < 0.01 (Welch test). 6;'% 0 100(C max - Cmin) / Cmin: 66,',,% are approxima t e 90% 

confidence limi ts. 

116 
60 

165 

160 

155 

150 t------""""-------i 

> 

.&l 

110 

C. 110 

c. 

o 10 

> C. 50f---------=--4 

c. 

20 

z 

o 10 

~ 

0: ~ o~----------~ ~ 

Z 325 

!oJ 

U 

Z 320 

o 

U 

19 5 

1110 

600 

550 

CCI2F2 

500t----------~ 

leo 

140 

100 

co 

-+---1 II e I--f.o 

TIME (months) 

Figure 58. --Three-month running averages of the monthly average concentrati ons of eight gaseous tracers 

of Arctic haz e at BRW. This provides evidence that the seasonal 

variations of these eight gases have 

repeated themse lves over the two 

winters of observation (Khalil a nd 

Rasmussen, 1982). 

ll7 
5.7.2 Criteria for Gaseous Tracers 

As table 38 shows, some tracers have more prominent winter maxima than 

others. Such tracers are desirable since their measurements can be used to 

estimate the contributions of various source regions more accurately than 

other tracers . The criteria for gases to be tracers of Arctic haze have been 

developed by Khalil and Rasmussen (1982) on the basis of data discussed earlier. In general the gases must (1) be entirely anthropogenic or must have 

large midlatitude anthropogenic sources, (2) have l ong enough lifetimes in 

winter to survive transport to the Arctic, and (3) have seasonal patterns that 

repeat year after year whenever Arctic haze is present. The seasonal pattern 

in condition (3) should mirror the seasonal pattern of Arctic haze aerosol; 

thus, maximllm trace-gas concentrations mu st occur during the half year including Arctic winter (Rahn, 1981b; Rabn et al . , 197 7). 

To satisfy the last condition the quantitative criteria 

C > C (~ $ 0 . 01) max min 

C > C, (~ $ 0.01) max 

were chosen , where C is the average concentration of the trace gas in the 

Arctic during three ~8~cessive winter_months between De cember and May when 

maximum concentrations are observed, C. is the average concentration during m.n 

the 3 months of summer (June to August), C1 is the ~verage concentration for 

the 9 months other than the three chosen to define C ,and ~ is the level of 

max - - significance at which the hypotheses C = C. and C = C[ can be remax m1n max - - - jected. It has been assumed that C ,C., and C1 are calculated after any max m.n 

detectable long-term trends have been subtracted from the data. The criteria 

establish the high probability that concentrations of a trace gas during winter are significantly greater than during summer or the rest of the year . 

The trace gases listed in tables 37 and 38 satisfy the criteria. Generally, the background concentrations of long-lived gases tend to be large 

compared with seasonal emissions, thus making it difficult to detect seasonal 

variatiollS. Thus, gases found to be the mos t suitable tracers were those with 

globa l lifetimes of less than 5 years or with concentrations far less than 

t hose expected if current yearly emissions were in equilibrium . 

5.7.3 Conclusions and Results Supported by Tracer Gases 

The measurements of trace gases at BRW support several conclusions of 

previous studies of the Arctic haze aerosol . In particular, the following 

co nc lusi ons ma y be drawn. 

( 1) The six anthropogenic halocarbons (CHCIF2, CC13F, CCl zF2 , C2C1 4 , 

CzHCI 3 , CH 3CCI 3 ) , and CO and CH 3CI are produced at the same midlatitude regions as t he precursors of Arctic haze. Their maximum concentrations in t he 

Arctic occur during winter, closely following the occurrence of Arctic haze . 

These gases can therefore serve as quantitative tracers of the distant origins 

of Arctic haze. 

(2) Since these gases are produced in industrialized and populated regions of the world, their increased concentrations during the Arctic winter 

118 
E 

~ 

-'" 

N 

t-" 

J: 

(!) 

W 

J: 

4 

3 

2 

O~~~-l-L-L-L~~~~ 

60 80 100 

CONCENTRATION (pptv) 

Figure 59 . --The concentration of C2Cl 4 

as a function of height on 2 different 

days (filled circles, 7 May 1982; open 

circles, 13 May 1982). Polluted air 

occurs between 1 and 3 km. 

can occur only because of long-distance transport. This result provides additional and independent support to previous studies indicating t hat t he sources 

of Arctic haze aerosol are anthropogenic and located in t he midlatitudes of 

the Northern Hemisphere (Ra hn, 1981b). 

(3) Several of the halocarbon tracers are released throughout the year 

and are so inert that their lifetimes do not vary significantly during the 

year. Their observed seasonal patterns are consistent with a faster transport 

during winter from polluted midlatitude locations to the Arctic. Such transport patterns may also contribute to the occurr e nce of Arctic haze. 

(4) Differences in the seasonal patterns of CFC-ll and CFC- 12 in the 

Arctic may indicate either the seasonal variations in the use patterns of 

these gases or the contributions of different sources to the Arctic atmosphere. Further studies may resolve whether there is a predominant location 

from which the Arctic ha ze aerosol originates or if pollution from a few separated locations combines to produce Arctic haze . 

(5) More recent studies on the variation of tracer gas concentrations 

with height suggest that polluted air may be transported in a layer between 

1 and 3 km and perhaps in higher layers as well . Figure 59 shows a n example of 

a height profile of C2Cl 4 (see also Rahn and Heidam, 1981). 

119 
(6) Currently, studies of the seasonal cycles of tra ce gases at BRW are 

continuing and are being supplemen ted with studies of the abundances of unique 

exotic gases in transit from specific industrialized areas of the world to the 

Arctic. It is hope d that this information will help reveal the origins of 

Arctic haze. 

5.8 Time Series Analysis of Light-Scattering Data from MLO 

M. Darzi and J . W. Winchester 

Department of Oceanography, Florida State University 

Tallahassee, FL 32306 

5.8.1 Introduction 

In previous reports (DeLuisi, 1981, pp.l07-113; Darzi and Winchester, 

1982a) results were presented of elemental analyses of a time series of aerosol samples collected each 3 .7 hours at MLO (alt. 3.4 km) during a 13-day 

spring dust period , April-May 1979 (Shaw, 1980). Aerosol sulfur often exceeding 1 ~g m- 3 was also present. Subsequently (Darzi and Winchester, 1982c) 

much higher dust loadings of continental composition were evident during 

spring than summer at the Hawaiian Volcano Observatory (alt. 1.2 km), which is 

consistent with interpretations ba sed on light scattering (Bodhaine et al., 

1981b). Time series analysis of springtime elemental concentrations at MLO 

showed strong coherency between sulfur and crustal dust e lements and a strong 

periodicity near 21 hours , suggesting t hat large-scale processes, possibly related to Asian aerosol sources, affected concentration flu c tuations at MLO 

during spring, rather than local meteorological effects from wllich a 24- h periodicity is expected. Moreover, crustal elemental concentrations were coherent with light-scattering data a lthough not with CN counts, indicating that 

light scattering can be used as a quantitative indicator of aerosol constituents. 

The record of hourly light-scattering data for four selected months during 1979 has since beell examined (Darzi and Winchester, 1982b). Strong diurnality was found during sun~er, fall, and winter, but a shorter principal period, near 21 hours, was found for spring, which is consistent with the elemental concentration measurements. Therefore, it may be possible to calibrate 

light-scattering data with elemental composition determinations for short time 

resolution, thus permitting the interpretation of extensive records of MLO 

light-scattering data si nc e 1974 in terms of dust, air pollution, and possibly 

other components of continental as well as local origin. In this report MLO 

1979 and 1980 light-scattering records are examined by time series analysis 

using measurements of bA at 450-, 550-, 700-, and 850-nm wavelengths and the 

-~ Angstrom exponent ~, defined by b

A - A . 

5.8.2 Results 

Hourly light-scattering data for 1979 and 1980 from MLO at the four wavelengths were provided by GMCC. For every hour of January, April, July, and 

October of each year a regression fit to the relation log b

A = -~ log A + constant was performed, and the correlation coefficient was generally >0 . 9. 

Hourly values of predicted log 6450 and log 6850 as well as ~ were comput ed 

from the regression line , thus making use of data at all four wavelengths. 

120 
g 

r-~ 

I 

• • 

-' • .J " 

.; , • 

I\. A /' A • 

" A ~ IrJ ! A IIV , VV 1\ 1\. ~ 

, • 

v y '-JV " ·V If"" [\I V ~ I\J . , . 0.( , , . . .. 

, 1 -; 

! 

• "/\ 1/\ A I ~A I A f\ r, I/' \~ -' • 

· A l~ tV 

IV \, 11 i ' v~ v~ I" M v , 00 

.; , V V IJV 1'v.J 

L, V 

• 

, 

.0 .00:1 ' 0.00 .'.013 lto.OC 'U.l"l ZOO.1Il ~a.ao 21!1 00 1211.00 1&0.00 ' (WI.DO " 0.110 'SJ.OO SlO.OII no III 'OO.m '.0.00 U4.00 ll0.e~ 

TI. (h) 

Figure 60.--tILO 4-h mean light scattering, log 0850, at 850 nm for January 

(upper) and April (lower) 1979. Bars at top cover the 12-h night periods 

2000-0800 HST. Note the January s cale, -8.0 to -4.0, and April scale , -7.2 to 

-4.8, for log 0 8 50 (m- 1 ). 

Four-hour means of these three parameters were ca lculated and used in subsequent time series ana l ysis. 

Light scattering, as well as elemental concentrations, often varies by 

severa l-fold over intervals of a few hours at MLO, indicating fluctuations in 

aerosol concentrations as air passes over the sampling site. The 4-h mean 

log 6 850 values for January and April 1979 ~re plotted in fig. 60. The January data show a general level of 6850 - 10 7 m 1. Additional peaks occurred 

at values at l east severa l times greater but not preferentially at any particular time of day or night. Unlike January when nighttime peaks are seldom 

observed, in April peaks often occur at night. The high light scattering and 

its pattern of variability, apparently not related to diurnally varying local 

meteorological conditions, are characteristics that suggest aerosol transport 

from Asia during spring. 

The eight monthly sets of 4-h mean values of log 685o, log 645o, and a 

have been subjected to time series analysis (Darzi, 1982, Appendix C). To 

examine the periodicities near 24 hours for the 8 months more closely, the 

variance densities at discrete Fourier periods from about 20 to 27 hours are 

listed in table 39 . Except for April, high variance densities near 24 hours 

are generally found. In both April sets, however, higher variance densities 

at about 10% shorter periods, 21-22 hours, are found. This result, together 

with generally highe r light-scattering intensities in April compared with the 

other 3 months each year, suggests unique aerosol characteristics during 

spring. 

12l 
Period 

(h) 

~ 

26.6 

25.7 

24.8 

24.0 

23.3 

22.5 

21.9 

21. 3 

20.7 

~ 

26.6 

25.7 

24.8 

24.0 

23.3 

22.5 

2 1. 9 

2 1. 3 

20.7 

Table 39 .--Variance densitie s at dis cre te Fourier periods* 

Ja n 

0.242 

0.201 

0.523 

1. 15 

1. 60 

1. 48 

1:J8 

0.956 

0.607 

0.229 

0.196 

0.435 

1. 03 

1.58 

1. 41 

0.945 

0.669 

0.407 

19 79t 

Apr J ul 

0 .06 19 

0.0398 

0 . 025 1 

0 . 0335 

0 . 0277 

0.0428 

0. 11 8 

0. 159 

0.0963 

0.0274 

0 . 02 19 

0 . 020 1 

0 . 0 19 1 

0.0217 

0 .0339 

0.0814' 

--- 0. 11 5 

0 . 0658 

0 . 0769 

0.0978 

0.156 

0 . 206 

0. 170 

0.0795 

0.0514 

0.0795 

0.0863 

0.0450 

0.0656 

0.0803 

0 . 106 

0. 120 

0.0786 

0.0467 

0.0530 

0 . 0636 

Oct 

0.353 

0.4 19 

0.622 

0 .459 

0.290 

0.29 1 

0.466 

0.622 

0.451 

0.260 

0.342 

0.474 

0.322 

0 .233 

0.254 

0 .409 

0 . 567 

0.374 

Jan 

0.704 

1. 08 

1.22 

1. 23 

1. 12 

0 .602 

0.315 

0.608 

0.75 1 

0.485 

0.766 

0.885 

0.934 

0.814 

0.39 7 

0.207 

0.4 18 

0.507 

1980t 

Apr Jul 

0.0283 

0.0 11 7 

0.0239 

0.0340 

0 . 0340 

0 .0272 

0 .0432 

0 . 0569 

0.029 1 

0.0184 

0 .0060 

0.0147 

0.0256 

0.0234 

0.0172 

0.0303 

0.0382 

0.0195 

0 . 0893 

0.315 

1. 17 

1. 61 

0.790 

0.396 

0.802 

1. 02 

0.881 

0 . 0783 

0.259 

0.840 

I. 08 

0.523 

0.322 

0.643 

0.782 

0.63 1 

Oct 

0.0732 

0. 125 

0 .262 

0.308 

0 .255 

0 . 297 

0. 264 

0.0987 

0.0391 

0.0478 

O. 101 

0.172 

0.167 

0.165 

0.255 

0 . 239 

0 . 0967 

0.0538 

-a ~':Hourly 4 -'1\ data at f'1LO fit by b - A . Resulting smoothed l og 6S50 and log 6450 , as 4-h 

means, analyzed by time series . 

tThe t .... 'o highest va lues in each set of nine a re underlined. 

Insight i nto whether the aerosol consists of a single population of particl es distri buted over a range of sizes, or two (or more) populations having 

different particle size distributions a nd varying somewhat independently with 

time, may be gained by examining coherency between light scattering at long 

a nd s hort wave l engths. Figure 61 shows coherency squared, plotted as a function of frequenc y obtained from the time series analysis. The right-hand 

scales give the equivalent confidence levels of coherencies. January and 

October 1979 have the highe st coherencies, bove the 99% confidence l eve l for 

nearly a ll periods from 10 to 300 hours. April 1979 ha s the lowest coherency 

and July 1979 is intermediate. These results s uggest that the January and 

October aeroso ls exhibit essentially parallel variations on conc entrations of 

pa rticles t hat scatter at long and short wavelengths; i . e., the particle size 

distribution exhibits little variability. In April the weaker coherency suggests the presence of fine and coarse aerosol components, as may be found in 

an ex t ernal mixture of sulfate and crusta l dust particles, and these exhibit 

somewhat independent variability in time. In July an intermediate result is 

found. 

Further insight i nto t he presence of fine and coarse aerosol components 

is gained f rom ave rage va lue s of a , listed in table 40 for the 8 months of 

1979 a nd 1980. The lower va lues of a for both Aprils than for the other 6 

months indicate a grea ter proportion of coarse particles compared with fine, 

during spring. This is consistent with the presence of continental dust. 

However , it should also be not ed that light scattering at both short and long 

122 
PER [00 - H0URS l ol 101 100 

- ~ I f • ------------f-- " 

~-- ------ -----

S5 

'" 

a 

00 "'. 

or 

~------------------------~oo 

~ ---------------~ 

. 

, 

a 

00 "'. 

or 

OJ 

u 

g 

1/79 

LO -~ 10- ' 

FREQUENCY - CYCLES/ H0URS 

PERI00 H0URS 1()2 10 1 100 

99 

S5 

90 

~------~~-----------Y~~~ 

------------ - -so 

7/79 

10-2 10-1 

FREaUENCY - CYCLES/H0URS 

a 

00 

J>~ 

or 

OJ 

u 

g 

o 

PERI00 - H0URS 102 10 1 100 

- .~ f - - --- -- -- ----- -- - }--

----------1---- --

4/79 

10-l 10-1 

FREQUENCY - CYCLES/H0URS 

PERI00 - H0URS 

" 

os 

'" 

80 

50 

\()2 10 1 100 

~-

==---------------~ --~~~~~~--: 

a 

0 0 "'. 

or 

~------------------------~BO 

~ - ---------------50 

10/79 

g 

O~ __ ~~~~~~~~ 

10-1 10-2 10-' 

FREQUENCY - CYCLES/H0URS 

Figure 61 .--Coherency squared of 4-h mea n l og 0850 and l og 0450 for January, 

April, July, and October 1979. Percent confidence l eve l s are indicated by 

scales on the right. 

Table 40.--Seasonal va ria tion of a* 

Nonth 1 

1979-80 a SD/ n'li 

Jan 1. 78 0.05 

Apr 1.28 0 .05 

Jul 1. 86 0 . 05 

Oct 2.25 0 . 04 

Jan 2 . 38 0.06 

Apr 1.45 0.05 

Jul 2.09 0.04 

Oct 1. 99 0 . 04 

*Based on n - 180 , 4-h means of 4-A light-scattering observations monthly - a at NLO. a i s defined by b - A . 

123 
wavelengths is greater during April than in the other 3 months each year. 

This could be due to a dust component of broad particle size distribution so 

as to scatter short- as well as long-wavelength light, but it may also be 

consistent with enhanced concentrations during spring of both fine and coarse 

aerosol components, e.g., sulfate and terrestrial dust. Aerosol sulfur 

concentrations have been reported (Darzi and Winchester, 1982a) for 23 April6 ~Iay 1979, averaging 0.3 fjg m-~, and often >1.0 fjg m-~, with similar time 

series characteristics for sulfur, iron, and the other crustal elements. 

These high concentrations and the time series results, together with air 

trajectories, suggested air pollution transport, along with dust, from Asian 

sources . Whether these high sulfur values represent spring enhancement or are 

part of a more persistently present fine component may be determined by 

s uitable aerosol sulfur concentration measurements at other times of the year 

at ~ILO. 

Further indication of the possibility of air pollution sulfur being 

transported from Asia during the spring dust season is given by 1980 measurements in Japan. In cooperation with investigators at Keio University, weeklong sequential streaker samples were obtained of aerosol with 2-h time resolution from two kosa (yellow soi l) dust events that occurred during the weeks 

of 19-25 April and 6-12 May 1980 (Hashimoto et al ., unpublished results); the 

first dust storm was also sampled in Beijing, China, on 19 April (Wang et al., 

1982). PIXE analyses indicate that the time of high dust concentrations 

(e.g., at Niigata for 2.5 days beginning 21 April) coincides with increased 

concentrations of aerosol sulfur at Niigata by 0.3-0.6 fjg m- S. These results 

suggest that Asian dust transported to Japan may contain an air pollution component. 

5.8.3. Discussion 

The location of MLO at a high altitude in the mid-Pacific makes it ideal 

for monitoring midtropospheric aerosol, especially for detecting long-range 

transport of continental dust and pollutants. This report points to the importance of comparing hourly light-scattering measurements with elemental concentrations that are also measured on a short time scale. Both sets of measurements are amenable to time series analysis and provide insights into dynamic properties as well as chemical composition as evidence of possible 

sources and transport pathways of aerosols to Hawaii. 

5.9 Radiation Measurements at BRW 

G. Wendler and F. Eaton 

Geophysical Institute, University of Alaska 

Fairbanks, AK 99701 

The "radiation paradox", which was measured at BRW, was described last 

year. On clear s unny days on Lhe North Slope the radiation balance at solar 

noon in May is less positive than on cloudy days, resulting in cooler amb ient 

air temperatures. Although the net short-wave radiation increases, the increase is not substantial because of the high surface albedo. This small gain 

is overcompensated by the greater loss in the infrared under clear-sky conditions. Measurements of the short-wave and all-wave budget with a PD-4 Davos 

radiometer continue. Further, three more sensors were added to measure sky 

radiation, radiation received on a surface inclined to latitude, and radiation 

124 
received on a south "all. From the gl obal and s ky radiation, the direct beam 

can be calculated. These measurements together with the budget measurements 

are of scientific interest, but the measurements on inclined surfaces are of 

greater practical importance. They can be used for estimating the size of 

photovoltaic arrays, "hich are connnercially used on the North Slope for 

microwave repeater stations . The data acquisiton system was changed to a 

Datel magnetic tape recorder . 

5.10 Optical Measurements of Blowing Sno" at SPO 

F. Eaton and G. Wendler 

Geophysical Institute, University of Alaska 

Fairbanks, AK 99701 

An optical system for measuring blowing snow was insta lled at SPO during austral summer of 1981-1982. The system is similar to that designed by 

R. Schmidt, but it was modified both electronically and mechanically by 

G. Mimkin in Fairbanks for use in extreme cold and corrosive (sea coast) 

sites. Low-temperature components were used, and the first year of testing 

low-temperature effects on the system will be carried out at SPO. 

The system measures both concentration of blowing-snow particles and 

sizes of particles. The sensor is mounted on the same tower as the GMCC 

temperature and wind speed and direction probes; thus the ensemble of measurements at one point will be very useful in understanding blowing snow. 

Interest in the effects of blowing snow caused by the katabatic wind 

stimulated the measurement program in Antarctica. Actual flux measurements 

of blowing snow are crucial to assess the importance of blowing snow due to 

density changes (by injection of particulate matter into the airstream, as 

well as by cooling of the air from sublimation of transported particles). Of 

particular interest for climatic studies are measureme nts of transported snow 

as it relates to the overall mass balance of the ice sheet in Antarctica. 

Blowing-snow measurements ca n also be used for understanding visibility and 

drifting snow . 

5.11 Light Absorption Studies at MLO 

A. D. Clarke and R. J. Charlson 

Department of Civil Engineering, University of Washington 

Seattle, WA 98195 

The aerosol light absorption coefficient a was meas ured twice daily at 

MLO from late April through late May 198 1. ThilPtime pe riod was chosen beca use it was the most probable time for Asian dust episodes there (DeLuisi, 

1981, pp. 107-113). The purpose of the measurement program was to determine 

values of a and its short-term variability at MLO, under conditions repre- ap 

sentative of the middle to upper troposphere, to identify the size fractio n of 

the aerosol responsible and to try to determine sources. 

A new technique, called the IS method (Clarke, 1982), was developed to 

meas ure the absorption rapidly under remote "clean" conditions. An 8-h sampling period at MLO was found sufficient for both day (upslope) and night 

125 
0.8 

0. 6 

0 .4 

0.2 

O~~ __ ~~ ____ ~ __ ~ __ ~~ 

OA 0 7 1 2 4 7 

Particle Diamete r (urn) 

Figure 62 .--A typical volume distribution of HLO aerosol as measured with a modified Royco OPC. 

Area under the curve is total volume measu red (~m3 cm- 3). 

(downslope) measurements employing this method. Aerosol samples were collected daily for both regimes , and a cyclone samp ler with a size cut at 

-0 7-~ m diameter was used to obtain fine-particle samples in addition to 

total-particle collections. Sample collections were made on both quartz fiber 

(Pallflex QAS 2500) and Nuclepore (0.4-~m) filters. A modified Royco 220 OPC, 

a three-wavelength nephelometer (Bodhaine, 1979 ), and a G.E. CNC were used to 

characterize the size distribution and the scattering coefficient a of the 

sp 

aerosol over the sampling periods. tleteorological variables includ ing wind 

speed, wind direction, inversion height (from Hilo rawinsonde data), etc., 

were recorded to characterize the air mass and to assist in discrimina tion of 

incursions of aerosol from below the inversion layer. The OPC provided optical sizing data in the 0.35- t o 9-~m range. Within this range the aerosol 

mass distribution typically revealed a well-defined bimodal character with a 

consistent minimum at approximately 0.7 ~m (fig. 62). Hass peaks for the 

large-particle mode were centered near 3 ~m, while the fine mode appeared to 

reach a maximum near the lower range of the OPC «0.35 ~m) such that only variations in the upper tail were mea surable. 

The short sampling period was unfortunate in that it coincided with relatively anomalous weather cond itions and a variety of instrument failures at 

HLO . Consequently, clear and complete data sought to characterize the Asian 

dust episodes during this sampling period were not obtained. However, it is 

believed that features in t he available data suggest significant characteristics of the aerosol at HLO, including Asian dust events. The primary variables of interest in this study are presented independently in fig. 63 as a 

function of da y of yea r . Wind speed, wind direction, and inversion height are 

taken from the Hilo rawin sonde data. Data denoted by stars were taken at 

night (downslope f l oW); dots represent days (upslope floW). Vertical arrows 

point to data off scale and have the off-scale values printed above them. 

Relative inversion strength (as mea sured over Hilo) is s uggested by the size 

of the data dot on the inversion height curve. Wind speed and direction (also 

measured over Hilo) are illustrated with wi nd direction (relative to North at 

the top of the page) pointing into the data point . The mass distribution 

plots were obtained from the OPC volume distribution by using an assumed density of 1 . 5 g cm- 3 for the aerosol. For the case of fine -particle mass, the 

volume detected by the ope in the range of 0.35-0 . 7 ~m has been doubled to 

estimate the remaining part of the distribution below 0.35 ~m and out of range 

for the OPC. Although this is an arbitrary choice, the fine ma ss as presented 

should be systematically uncertain by less than a fa ctor of 3. 

Comparisons of cycloned and uncycloned samples revea led that approximately 60%-85% of the absorption was due to the mass in the fine mode. Values 

126 
c 

0 

;; 

" e-

~. D, 

.~ 

2: <,605 

~ 

st 

~ ". c '. 

o~ 

~2. 

• 

. 

u 0 o.a ~ 

0 OD 

A.'; 

c 

:;; . ,8 

" c 

0 

:!. ,. ~, 

~E 

0 SF 

co 

o~ ,. ';::; x e-~ 

~ D 

~ • 

" D" 

~ · D,' 

~ · ~ 0 .3 ' r 10'" ~ , 

:: e 0 .2 U~ '. ~ t 01 

:l. 

· · • E 

0 

U . t'E; 

.~ 

O~ 

.. 

" 0 

~ 

-

c 

0 'v 

~, 

~E 

0 er 

~o 

c~ 

.~ 

" . 

~ 

• U 

~ 

,. 

E 

U 

5~ 

~ 

~ 

~ ~ 

' .. 

~~ 

cO 

o~ 

· . 

1 "~ 

~ 

• 

, 

• 

3 

• 

,. 

•• 

3. 

,. 

,. 

• 

" 

• 

• 

• 

.. 

" 

,. 

" 

: 10 

"g e .5 

, 

. 

" " , , , , 

, 

• 

• 

:--e"\ 

" 

• • 

• , .",,/, ~ . I· . , I \ • 

'

. 

.. 

. , I •• ' .. .. 

~ . ,f ...... 

" " • 

'1 \' 

A 

", 

¥ , ~ , , 

~ 

I 

" '\ 

" , , " " ~ ~ '\ , .. .' .,. '/" 

L. O.S>·1 

. , '. 

• 

" " " , , , , , 

, 

, 't. , 

"-'", , , , 

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, 

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, 

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tiS •• 75 

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, 

, 

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:' " " • 

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• " '-.... i, , " " ,; , r., ' .. 't: ... 

, 

, 

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I .. 1 I ' I , . , 

" ", ' \ /'. ' 

\ ... :./ '.. ..... ,-' " •• . ! .o'. ..... ' ............... '.' ..... _. -.~ 'tI' • 

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...-''''''', '" "'~ , ~~, ...... • '~~~~~~-T-'~~~~~~'-~~~~~~-'~~~~ 14 9 ISO IS ' 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 161 '68 169 170 171 172 

DOV 1981 

Figu.e 63.--Ae.osol optical, physical, and ae.omet.ic data at HLD, 

text fo. detailed expla nation of symbols. 

127 

See 
for specific absorption B presented in fig. 63 are calculated using the estimated fine-mode mass withathe assumption of an average of 75% of the absorption attributabl e to that mod e . In spite of these assumptions the ma gnitude 

and relative var i ati on of B are va luable indi ca tions of the aerosols and air 

a 

mass. 

Hilo is located approximate ly 60 km northeast of NLO, and during the predominant trade wind flow the rawinsonde data taken there represent generally 

unperturbed charac teristics of the air mass approaching the island. Orographic effects will modify wind speed, wind direction, and inversion he ight 

during its approa ch to NLO, and diurnal ups lope and downslope flows will be 

superimposed on these characteri stics in the vicinity of NLO (Nendonca , 1969). 

Consequently , separate sampling was performe d during upslope (day) and downslope (night) conditions . Nighttime samples are indicated on the time axis 

with a darke ned line segme nt a nd on the plotted values with a star symbol. 

Dashed lines co nne c ting data points are illustrative and intended to indi ca t e 

periods of consecutive sampling. No data for the light-scattering coefficient 

were avail ab l e fro m the GNCC nephelometer because it was out of service. Figure 63 data commencing on DOY 157 were from a nephe l ometer obtained cou rtesy 

of A. 11aggo ner of the Unive r s ity of Washington. 

Several events should be noted in conjunction with an interpretation of 

fig. 63 data . The first 3 days of samp ling (148-150) were concurrent with a 

significant fo r est fire burning out of contro l in Volcanoes National Park approximately 50 -km directly upwind of ~ILO. Both the mass and the absorption 

coeffi cient s how large diurnal excursions with nighttime minima for these 

dates; the se may be due to diurnal upslope winds bringing some soot and as h to 

NLO. Hig h CN co unts also s uggest intrusions from the lower troposphere. Similar intrusions are mo re c onspicuous for DOY 165-168. Though total ope lIIa ss 

mt remains relative l y low i n this period, the fine-particle ma ss mf , a J a , sp ap 

B , and a weak high inversion a ll signal a prolonged invasion of the trop~sp eric aerosol. SEN photos during this event show numerous chains of particles simila r to ca rbon, of combustion origin, which account for the hi gh 

spec ific absorption for the fine-mass fraction in thes e samples. 

Primary data for the period 151-164 reveal a more complex variation. 

With the excep tion of a f ew daytime va lue s for this period, both the CN count 

and inversion height remain relatively low. At the same time, day and night 

values for a , 0 , mf , and mt are high and s how similar variations over 

s p ap 

time. Unfortunately, a va lues prior to DOY 157 do not exist, so single- _ sp 

scattering albe do w cannot be determined for those dates. However, whe n 

comp ared wiLh the high-inversion period mentioned earlier, the specifi c abso rption based on the estimat e d fine-particle mass maintains remarkably low 

values during the particularly high mass loading for DOY 15 3-157. In view of 

this, and SEN photos revealing irregular angular parti c les with a predominantly terrestrial mineral e l emental compo sition, this period may represent 

long-distance transport of Asian dust. 

The above considerations and other predomina nt features in this data set 

are summarized in table 41. Pending further analyses of these data and mor e 

extended data sets t o be collected in 1982, this summary is presented as tentative. In spite of the anomalous meteo rology during this study, some features of the da t a appear significant and warrant comment. Ignoring daytime 

sampl es and other periods of upslope flow or intrusions of high aerosol ma ss , 

128 
DOY 

149-152 

152-155 

155-161 

161-164 

164-167 

167-172 

Table 41. --Summary of fig. 63 data features 

Fea ture 

Strong day-night 

mf , "'t' eN 

variability of a , ap 

(1) Large excursions 1n mf and mt with 

some high night values 

(2) LoweN variability 

(3) High winds 

(4) Average inversion 

(1) 

(2) 

Coincident maxima in mf , rut' a , 

a ,both during night and daysp ap 

LoweN except DOY 156 

(3) Low iii 

(4) Noderate 

(5) SEfl-EDXA 

B 

a 

shows 

and S 

strong crustal 

elements pre sent 

(6) High winds associated with low 

pressure north of Hawaii 

(1) 

(2) 

(3) 

(4) 

Low mf , rut' 

High iii 

High winds 

eN, a ,a sp ap 

Low weak inversion 

(1) Hoderate to high m

f 

(2) Low m

t 

(3) High CN , asp' aap' Ba 

(4) High weak inversion 

(5) Average winds 

(6) SEH-EDXA shows crustal elements, 

(1) 

(2) 

(3) 

NaCI, high Ci fibers, and carbon chains 

LO\o,I rut 

Diurnal variation in m , eN, asp' 

a ,w, and inversion ~eight ap 

Low variable winds with some 

upslope flow 

129 

Probable event 

Strong upslope-downslope winds carrying 

some ashes from a 

forest fire 50 km 

downwind during day 

Possible Asian dust 

intrusion 

Asian dust suspected 

and/or lower 

tropospheric air 

Possible example of 

background or 

typical aerosol at 

flLO 

Injection of boundary 

layer air \.Jith 

crustal, marine, and 

combustion components 

Example of background flLO aerosol 

with some daytime 

incursions of upslope 

boundary layer air 
Table 42.--Characteristics of ~ILO background aerosol 

Fine Total 

DOY a a mas s''; mass B t w 

sp ap a 

ex 10- 7 m- 1 ) (x 10- 7 m 1) (jJg m- 3) (jJg m- 3) (m2 gm- 1 ) 

158 8 . 0 0.22 0 .051 0.291 0.32 0.973 

167 5.2 0.16 0.030 0.085 0.42 0.968 

170 3.5 0.19 0.017 0.042 0.83 0.948 

171 3.6 0.12 0 .01 8 0.032 0.50 0.970 

172 4.5 0 . 18 0.024 0.067 0.56 0.962 

Aver. 4.96 0.174 0 . 024 0 .103 0.526 0.964 

,"Es tima ted fine mass based on OPC mass (0.35 < d < 0.7 jJm) and assumed 

density of 1.5 (s ee text). p 

tSpecific absorption of estimated fine-mode mass using typical 75% absorption 

due to fine mode (see text). 

there is evidence of concurrent minimum va lues for several quantities. During 

the measurements , these minimum conditions occ urred during approximately onehalf of the evenings sampl ed . Although a more extensive set may alter or reduce these values, they are presented here as sample values for an upper troposphere background aerosol. Prilnary aeroso l characteristics meas ured during 

five minimum nighttime periods when a values were available appear in 

table 42. sp 

The two derived quantities in fig. 63, the single-scattering albedo 

(~ = a I [a + a )) and the specific absorption (B = a Im f ), are of par- sp sp ap a ap 

ticular interest. The former quantity is a fundamental parameter for global 

climate models. If the above data, excluding pronounced events , are represen£ative of the ~ILO aerosol and the upper troposphere, then a typical value 

of w for the background aerosol appears to be approximately 0.97. This represents triple the absorption found in many "models using an assumed value of 

0 . 99. In spite of the assumptions used to es timate specific absorption in 

fig . 63, the daily variability and incursions from the troposphere sta nd out. 

The remaining values of B show remarkably l i ttle variation in comparison with 

a 

those for mf and are not far removed from values reported for remote continental areas (Weiss and Waggoner, 1980) . 

Since the size cut used here results in a fine-mode ma ss less than that 

typically analyzed by others, these values will be somewhat higher by comparison. However, they still indicate that substantial absorption is present on 

a fine-mass basis and are suggestive of a continental source. An extended 

sampling program is necessary to establish the gene<ality of these observations and to identify the nature of the primary absorber . Should high spe -

cific absorption be a persistent trait of the background fine-mass aerosol, 

then graphitic carbon is a likely candidate. If this obse<vation is typical 

for NLO, then long-distance transpo<t may play an important role in both Asia n 

dust episodes and in maintaining the character of the ba ckground aerosol. 

l30 
5 . 12 Eight-Year Air Chemistry Measurement Program at SPO 

D. Cronn and E. Robinson 

Air Pollution Research Section, Co ll ege of Engineering 

Washington State University, Pullman, WA 99164 

The objective of this program has been to mea su r e the changes in the 

atmospheric burdens of the trace gases CFC- 12 (CC12F2), CFC-II (CC1 3F), carbon 

tetrachloride (CCl.), methyl chloroform (CH3CC1 3), and nitrous oxide (N20) at 

a site (SPO) far removed from the anthropoge nic sources (natural biogenic 

sources for N20) that are predominantly in the Northern Hemisp here . Samples 

have been collected on a nearly annua l basis since January 1975 and analyzed 

by gas chromatography with electron capture detection based on a consistent 

set of long-term calibration standards . The measurement periods and the 

mixing ratios for each component are given in table 43. Gaps in the data 

record have been filled by data collected at Mdlurdo station (-78°S) or t. 

John, South Island, New Zealand (-43°S) . The data set is compl ementary to 

(1) the GMCC air sampling data a lso collected at SPO , (2) annua l latitudinal 

gradient studies made from 34°N to 78°S l atitude of these same trace gas 

species sinc e 1976, and (3) continuous ground-level monitoring by WSU since 

1975 at a nonurban, midlatitude Northern Hemispheric site. 

Each compound has had an increase with time as shown in table 44, although the slope for N20 is only marginally significant. The percentage increases per year at the SPO based on a linear regression have been 6 . 8% ± 0.5% 

for CFC-ll, 5.8% ± 0.3% for CFC-12, 2.1% ± 0.4% for CCl., 8.1% ± 0.7% for 

CH3CC1 3 , and 0.3% ± 0.1% for NzO. These increases compare favorably with similar time trend data from the WSU monitoring station in the Northern Hemisphere (7.0% for CFC-11, 6.4% for CFC-12, 1.7% for CCl., 12% for CH 3CC1 3 , and 

0.4% for N2 0). An inspection of the data in table 43 also shows that the rate 

of increase for CFC-l1 and CFC -12 has diminished through the course of the 

Table 43.--Annual time trend of air sampling data 

Time Location CFC-ll CFC-12 CCl. CH3CC13 N2O'" 

(pptv) (pptv) (pptv) (pptv) (ppbv) 

Jan 75 SPO 90 120 54 

Jan 76 C~lt 113 195 121 57 

Jan 77 SPO§ 127 215 126 67 297 

Nov 77 SPO 140 234 129 82 300 

Dec 78 SPO 153 253 132 92 301 

Sep 79 N.ZJ" 160 270 138 106 298 

Nov 80 SPO 17lt 280 131 105 300 

Nov 81 SPO 180 299 141 1I3t 303 

*Based on present calibration (0.9038 x prior ca libra tion) . 

tGround samples from McMurdo area. 

§Aircraft sampling in planetary boundary layer within 30 mi of SPO . 

"""'From Mt. John near Christchurch, New Zealand. 

131 
Table 44.--Linear regression a nalysis of time trends 

Trace gas compound Slope SEE,' Intercept r 2 t 

CFC-I l 12.7 pptv yr -1 0.86 97.7 0.973 

CFC-12 17.6 pptv yr- 1 0.87 179. 7 0 . 988 

CCl 4 2 . 9 pptv yr -1 0.51 119.7 0.843 

- CH3CCl 3 9.6 pplv yr 1 0.85 51.3 0 . 954 

N20 0.8 ppbv yr- 1 0.42 296 . 2 0 . 479 

,',S tanda rd error about the regression line. 

tCorrelation coefficient squared . 

measuring program. This is in keeping with the curtailment in the rate of 

growth of emissions following recognition that these compounds deplete stratospheric ozone. Rasmussen et al. (1981) have described the spa time trends of 

these compounds with more statistical detail. They used the January 1975-

January 1977 data shown her e along with data gathered independently during the 

period 1978-1980. 

Acknowledgment 

This research has been supported by NSF under grant nos . OPP 76-00437, 

DPP 76-00437AOl, DPP 77-22866, DPP 7921003 , and DPP 8117488 . The progr~ 11 1 w~s 

directed by R. Rasmussen from January 1975 to June 1977. 

5.13 Trace-Element Sampling at BRW 

K. A. Rahn 

Center for Atmospheric Chemistry Studies, Graduate School of Oceanography 

University of Rhode Island, Kingston, RI 02881 

During t he last year, trace-element data from URI' s first 4 years of 

aerosol sampling at BRW (September 1976-Sep tember 1980) have been consolidated 

and finalized. Results are very reproducible from year to year with characteri stic seasonal patterns of both natural and po l lution-derived elements. 

Data for t h ree pollution-derived constituents in individual samples are shown 

in figs. 64-66 . 

Noncrustal Hn (fig. 64) ha s two maxima, in December a nd Narch. The December maximum is normally roughly one-half as high as the Harch maximum, although it can be as high. The Harch maximum is considerably broader than the 

December maximum. 

Noncrustal V (fig . 65) has the same two maxima plus a third in early Febr uary . The February maximum is quite variable in intensity, and is not always 

present. The Harch maximum is relatively stronger than it is for Hn. 

Nonmarine sulfate (fig.66) has a weak ma ximum in December and a mu ch 

stronger one in Narch-April. The latter lasts for nearly a month longer than 

132 
,. , 

• . . . . • 

• ,. , • 

DDY 

···1 ODD 2 6 •• 1 " " " 5 

Figu re 64.--Seasona l variations of noncrustal Nn (Xl'1N--in ng m 3) vs. 

DOY (1 Sep = DOY 1) for BRW, 1976-19 81. 

" '" 

• ,. , . 

• 

'" 

.. , 

,. , • .' 

•• .. • .. ' 

" " " '" '" '" DOY lfGfIiO. 1/'1 a D II 2 ••• 4 " It .. 5 

Figure 65 . --Seasonal variations of noncrustal V (XV) . 

legend. 

133 

'" '" '" 

See fig. 64 
4000 

3000 

2000 

1000 

" " 

" ., . 

" '" 

• •• 

. ,. o ••• 

'" DOY 

'. . , . . 

.. , , 

'" '" UG(NO,ll1 "'1 ODD! • •• , •••• ___ 5 

, 

'" '" 

Figure 66.--Seasonal variati ons of nonmarine sulfate (XS04). See 

fig. 64 legend. 

it does for noncrustal Mn and V, and appears to be a photochemical effect, 

because the length of the day is increasing rapidly at this time. 

The differences in composition between 

the aerosol has had different source areas. 

be primarily Asian, whereas t he March-April 

influe nce. 

the various maxima suggest t hat 

The December maximum appears to 

maximum shows a greater European 

5.14 Graphitic Carbon -to-Lead Ratio as a Tracer 

for Sources of t he Ar cti c Aeroso l 

H. Rose n, A. D. A. Hansen, and T. Novakov 

Lawrence Berke l ey La boratory 

University of California, Berkeley, CA 94720 

and 

B. A. Bodhaine 

Geophysical Monitoring for Climate Change 

NOAA/ERL, Boulder, CO 80303 

Recent studies at BRW indicate the presence of large aerosol concentrations that appear to be characteristic of the Arc ti c region as a whole (Rosen 

e t a1., 1981; Rahn and McCaffrey, 1980; Shaw, 198 1; Bodhaine et a1., 1981a). 

If the obvious natural aeroso l comp onents (e.g . , sea salt and so il) are exc luded, the predominant components of the Arctic aerosol are carbon- and 

134 
sulfur-containing particles. These particles occur at concentrations comparable with those found i n urban areas in the continental United States (Rosen 

et a l. , 1981; Ra hn and McCaffrey, 1980). 

There is considerable i ndirect evidence that a major part of the Arctic 

aerosol is produced f rom combustion processes. However, t he strongest and 

most direct substantiation of this is provided by the identification of l arge 

concentrations of graph i tic carbon in the Arctic (Rosen e t a l . , 198 1) . These 

graphitic s pe cies ) which have a struc ture similar to carbon black, ca n only be 

produced by comb usti on processes . The concentration of these partic l es at 

BRW during the winter and s p ring approache s that found in urban areas (i.e., 

the concentrations are only a factor of 4 less than t he average va lues found 

in Berke l ey, Calif ., and Gaithersburg, Md., and a factor of 10 less than those 

found in New York City). 

Associated with these graphitic species are large optica l absorp tion coefficients (~10 m2 g- 1), which could produce a significant perturbation of the 

heat balance over the Arc t ic . Preliminary model calcul ations indicate that 

present s pring concentrations of graphitic particles could increase the atmospheric hea ting rate by an amount that is comparable with that expected from 

do ubl ing the CO 2 concentration (Porch and MacCrac ken , 1982; Cess, 1982). 

The sour ces of the Arctic aeroso l a r e presently unknown. Part of the 

aerosol may be due to lo ca l Alaskan sources , but there is considerable evidence t hat a major fraction is due to long-range transport from other industrialized regions (Peterson et al., 1980; Barrie et al., 1981) , wi th Eurasia 

suggested as a major source area (Rahn and McCaffrey, 1980). The use of the 

graphitic carbon-to-lead ratio as a tracer for the sources of the Arctic 

aeroso l is reported in this paper. 

An aerosol sample r ha s been operating at BRW since October 1979, collecting parallel filter sampl es on 47-mm quartz fiber and Mi llipore substrates 

at a flow ra t e of approximate l y 1. 5 ft' min- 1 . Measurements of graphitic carbon and parti cu late lead concentrations from October 1979 through May 1980 are 

r eported he re. The graphiti c carbon concentra tions were obtained using the 

LBL l aser transmission t echn ique (Rosen et al . , 1978) with a n empiri cal calib ra tion curve developed for urban particul ates in the United States (Gundel 

et al . , 1981). Independent meas ur eme nts of t he graphitic carbon concentration 

by an op tico-thermal a na l ysis technique are under way. Lead concentrations 

were determined using X- ray fluorescence ana l ysis. 

Na tural concentrations of particulate lead are very low, and it is usually ass ume d t ha t in polluted environments the major sour ce is from the burning of lea ded gaso line by automobiles. Typica l ground- l eve ! l ead concentrations in urb an atmos pheres in the United Sta t es are ~2 g m 3 . In the Arcti c 

the concentrations are muc h sma ller , as s hown in fig. 67(a), but are p robably 

also combustion gen erated since the enrichment factors relative to the Earth's 

ave rage crustal abundanc e are large . For comparison the graphiti c carbon concentration as a functio n of the time of year i s s hown in fig. 67(b). Although 

both aerosol comp onents s how their l argest concentra tions during the winter 

and spring , t heir seasonal var i ations are quite distinct . Whereas the graphi tic carbon concentrations are roughly constant from December through April, 

the lead concentrations s how a rather sha rp peak in November a nd December and 

relatively l ow va lues for the rest of the year . As a res ult of t he se differences in behavior, t he relative co ncentrations of graphiti c carbon to lead 

135 
'" 'E 

'" c 

c 

0 

'';:; 

0 

~ 

C 

Q) 

u 

c 

0 

u 

u 

0 

Q) 

-.J 

40 

35 (a) '" 500 (b) 'E 

'" c 30 c 

.Q 400 

"0 25 ~ 

c 

Q) 

u 

c 300 

20 0 

u 

c 

0 

15 .D 

~ 200 0 

u 

10 u 

J:: 

a. 100 

0 

5 ~ 

<.!) 

Sep Nov 

Dec Oct Dec Apr Jun 

Figure 67 .--(a) Particulate l ea d concentration and (b) graphitic carbon 

concentration, each as a f unction of the time of year for 1979-1980. 

change substantia lly throughout the year, as shown in fig. 68. These variations could represent the contributi ons of different source regions during 

different time s o f year or represent a seasonal variation in t he fuel mix of 

given sour ce regions. It should be emphasized that the results reported here 

are only for 1 year , and i nterannual variation due to variability in the air 

trajectories that a rrive at Barrow from year to year could be conside r ab l e. 

Interpretations of these resu lts are based on several crucial assumptions: (1) the graphi tic carbon- to -Iead ratio does not change significantly 

during transport because of different deposition rates for particulate l ea d 

and graphitic carbon, and (2) source regions may be characterized by groundl eve l graphiti c carbon-to-Iead ratios (i. e., these ratios do not change appreciably with altitude) . These assumptions need fu rther investigation. 

It is interesting to comp are the graphiti c carbon-to-Iead ratios in the 

Ar c ti c with typical values in the Weste rn and Eastern Uni t ed States . As s hown 

in fig . 68, the va lues in the Ar c tic are conside rably l a rger than thos e found 

in t he United States , especially during the tlar ch-April time pe riod . During 

this time pe riod, t he average value is 10 time s that fou nd in t he Eastern 

Unite d Sta te s a nd 30 times that fo und in the West ern United States . If the 

graphitic carbon-to-Iead ratio in the Western United States i s used to repre -

sent a s ource region dominated by automotive emissions , then t hese re sults 

could imply that source regions of the BRW aerosol during the tla r ch-April time 

frame do not have a l arge a utomotive comp onent relative to other sootgenerating combustion sources. For example, s uch a region could ha ve a la rge 

diesel, wood-bu rning, or s tationary-source comp one nt relative to automobiles . 

Furthermore, these results could i mply that the United States or r egions with 

similar fuel mixtures do not contribute significantly to the Arctic ha ze during these periods of high graphitic ca rbon-to - l ead ratios. 

136 
II ,-~~-'------ .--r-,--~'--r-', 

100 

Figure 68.--Ratio of concentrations 

of graphitic carbon to particulate 

l ea d as a function of the time of 

year for 1979-1980. Also shown are 

the range of values for the Western 

United States (Anaheim, Berkeley, 

and Fremont, Calif.) and the Eastern 

United States (New York, N.Y.; 

Argonne, Ill.; and Gaithersburg, 

Md.). The range of values is defined as those values within one 

standard deviation of the average. 

9 0 

80 

o 70 

60 

& 

Acknowledgment 

Feb Apr Jun 

This research was supported by NOAA under contract no . NA31RAG00254, and 

by the Assistant Secretary for the Environment, Office of Energy Research, C02 

Research Division of DOE under contract no. DE-AC03-76SF00098. 

5.15 Effects of Sulfate and Non-Sulfate Particles on Light 

Scattering and Precipitation Chemistry at ~!LO 

5 . 15. 1 Introduction 

A. C. Dittenhoefer 

Enviroplan, Inc., 59 Main St. 

West Orange, NJ 07052 

Atmospheric transmission, eN concentration, and particle light scattering 

have been continuousl y monitored at MLO with the purpose of establishing longterm trends in global backgro und turbidity for investigation of possible climatic effects. Precipitation chemistry at MLO and various other island locations has a l so been monitored in recent years. However, only a limited number 

of studies have been conducted to investigate the chemical and physical properties of the aerosol at MLO. During the period March 1980-April 1981, a 

field study was conducted to mea sure t he size distributions and mass concentrations of sulfate and non-sulfate particles at MLO to evaluate their impact 

on light s cattering and precipitation chemistry. 

5.15.2 Experimental ethod 

A complete description of the experimental procedures used in the aerosol 

sampling and analysis is given in Dittenhoefer (1982). Particles were sampled 

on a raised platform approximately 5 m above the ground in a remote area of 

the observatory. Particles within the size range 0 . 1- to 2.0-~m diameter were 

collec ted with a cascade impactor onto Forrnvar-coated electron microscope 

screens. Sampling times were generally 1 hour at an impactor flow rate of 

17.5 Q. min- 1 . 

To obtain the size distribution of sulfate and non-sulfate particles, a 

BaC12 spot test was applied. After particle co llection, a layer of BaC12 was 

vacuum evaporated onto two of the electron microscope screens. One s c reen was 

137 
then humidified at 75% to activate all chemical forms of sulfate, while the 

other screen received no humidification such that only s ulfuric acid could 

react with the BaC12' A series of electron mi crographs was take n across the 

line of impacted particles on each screen using the University of Hawaii-Hilo 

transmission electron mi croscope. The particles were then counted, sized, and 

ca t egorized by type to estimate the size distributions of sulfate and nonsulfate particles, as well as the ratio of sulfuric acid to total s ulfate . 

5.15 . 3 Results 

Of the approximately 75 samples collected during the nocturnal downslope 

flow at MLO over the 13-mo period, only 16 were c lassified as being completely 

devoid of contamination by local vo l canic activity a nd high-humidity subinversion air. These 16 samples, believed representa tive of mi dtropospheric, 

natural-background aerosol particles, displayed wide variations i n their chemistry and morphology. 

Episodes of high concentrations of optically dense, non-sulfate partic l es 

occurred in the spring. There is considerable evidence that these were soil 

dust particles that originated from dust storms over the Gobi Desert in eastern Asia. Particle chemical analysis using a SEM X-ray mi croprobe (conducted 

by G. Shaw of the University of Alaska) revealed the predominance of the 

crustal elements Mg, Al, Si, K, Ca, and Fe in these samples. Particle lightscattering coefficients and mass concentrations measured during the springtime 

dust episodes were over 2 orders of magnitude l arger than measuremen ts typically observed under clean background conditions duri ng other times of the 

year. These episodes were a l so chara c t erized by a r elatively flat particle 

size distribution in the optically active size range, favoring the large soil 

particles. 

Sulfuric acid was the dominant er~so l ~omponent during very clean nocturnal downslope flow. The average NH4 ISO. aerosol mass ratio was estimated 

at approximately 0.07, indicating very little neutralization of the s ulfuri c 

acid by ammonia i¥ the=midtropospher e over Hawaii. This rati o agrees quite 

well with the NH. ISO. ratios in ~lLO precipitation , s uggesting that the wet 

removal of acidic sulfate aerosols could account for the rela t ive l y low pH of 

rainwater collected at MLO. 

By use of the measured sulfate and non-sulfate particle volume distributions, together with the theoretical relationship between Mie scattering 

efficiency and optical particle size parameter (Fri ed l ander, 19 77), it was 

possible to compute light scattering as a fun ction of particle diameter . The 

ratio of light scattering at 550 nm caused by sulfate particles to scattering 

caused by all particles is shown in fig. 69 as a fun ction of diameter, ca t egorized by the slope of the particle size di tr bution, . Sulfate s clearly 

dominated light scattering for sizes less than 0.4 ~m . At larger particle 

sizes, the influence of non-sulfates be came important, especially when the 

slope of the size distribution was small . 

Figure 70 s hows that the sulfate-to-total-partic l e scattering ratio and 

the slope of the particle size distribution were linearly r elated and highly 

corre lated. Use of the regression line in fig. 70 r epresented a means for 

estimating the relative contribution of s ulfate particles to observed light 

sca ttering at MLO using only the four-channe l nephelometer data. This was 

138 
10 -- s, 

" ..... ~5 

09 - - t3 >5 .... 08 .... .... .... '. 

07 .... ,',-

_"I 00 

". '- . . .. :'-..... f!.'" .Dr. 0.5 '-

0 4 , 

... '\ ... '. 

0 ' \ 

02 \ 

\ 

01 \ 

\ 

°0.1 02 04 OG 08 10 20 

0 (,../ 

Figure 69.--The ratio of l i ght scattering cause d by sulfates to total 

scattering as a function of diameter, 

categorized by t he sl ope of the particle size distribution, ~. 

10 

0.9 

0.8 

0.7 

~ 0.0 ::: ~ 05 

0.4 

{tyls • -044 -0.1 96 

0.' b~ 

02 r'096 

. .' OJ 

00 2 , 4 5 0 7 

~ 

Figure 70. --The ratio of light scatt ering ca used by s ulfates to total 

scattering as a function of the slope 

of the particle si ze distribution , ~. 

applied to each component of a 5-yr IL O historical nephelome t e r data set, 

which consist e d of hourly average scattering coe fficients for the hour beginning at 1200 Z (i.e . , 0200 LST), screened to exc lude cases of contami nation 

by local volcanic activity and moist s ubinve rsion air. The estimated annual 

variation of light scattering caused by sulfates a nd non-s ulfa t es is s hown in 

fig. 71. It is clearly evident tha t the spri ngtime pea k in light scattering 

a t ~ILO is mainly due t o non-suI fate particles, with scattering due to sulfate 

displaying comparatively little variation over the annual period . Sulfates 

and non-s ulfates contribute about equally to light scattering during the l a tter half of the year. 

The historical nephelome ter data set was also analyzed with respe c t to 

10-day air mass back-trajectories e nding a t 1200 Z at MLO. Transport winds 

were averaged withi n the vert ical layer between 3, 000 and 5, 000 m usi ng the 

ARL trajec t ory model. The ba ck-trajectories were divided into five categories, corresponding to the NE, SE, SW, and NW quadrants and a special NW-E 

case (to account for 10-day back-trajectories originating from t he northwest 

but arriving at MLO from the east), using the t yping scheme of Miller (1981b). 

-hoC)H- SI.IJATU 

- - --IUJAt U 

• 

---,,.~/---........ -------- o~~~=;:_:;_:~~~~ N At.! AS ONO 

Figure 71.--The a nnual variation of 

particle l ight scattering caus ed by 

non-s ulfate and s ulfate particles . 

139 
Table 45 .--Average light-scattering coefficient, Angstrom exponent, 

and estimated scattering coefficient due to sul fates, 

according to air mass trajectory type 

b 

_sp _ Traj ec t ory type Ci 

NW 

NW-E 

SW 

NE 

SE 

(x 10 6 m 

1.56 

1.46 

0 . 85 

1. 10 

0.72 

1 ) 

1. 80 

1. 70 

2 . 24 

1.71 

2 . 45 

0.30 

0.18 

0.13 

0.14 

0.17 

Table 45 s hows the average light-scattering coefficient at 550- nm I>avelength, 

b ; the average Angstrom exponent computed from the four-channel nephelometer s p 

data, Ci (which describes the wavelength dependellcy of light scattering); and 

t he estimated scattering coefficient at 550 nm caused by sulfate particles, 

(b ) , for each trajectory type. Flow originating from t he northwest is 

sp s 

clearl y associated with high light-scattering coefficients and low Angstrom 

exponents, indicating relatively high concentrations of large particles, and 

provi ding further evidence of the infillence of Asian soil dust. Light scattering associated with large-scale flow from the SW and SE quadrants is 

roughly half that for NW £10\' and considerably less influenced by larger particles. Scattering due to sulfates is Rlso highest for meteorological transport from the NW quadrant, implicating anthropogenic pollution sources in 

China and Japan as possible contributors (Darzi and Winchester, 1982a). 

5.16 Stochastic Simulation Modeling of the Global Carbon Cycle 

L. P. Steele 

CSIRO Postdoctoral Students hip Program, Limestone Ave . 

Ainslie, A.C.T., 2602, Australia 

The objective of this study was to examine some existing ma t hematical 

mode l s of the global carbon cycle using methods derived from control and 

system theory . The detailed results of this work will be available in a 

repo rt currently being prepared for CSIRO. 

The approa ch ma y be thought of as a generalized sensitivity analysis of 

the mode l s of the carbon cycle. First, the model parameters are represented 

as statistical distributions that reflect the degree of certainty in the value 

of each parameter . Then one or more problem-defining behaviors of the system 

(such as the Suess effect or the increasing atmospheric concentrations of CO 2 ) 

are stipul ated and a classification algorithm applied to the output of each 

model simulation . Monte Carlo simulations can then be performed, allowing the 

analysis to focus on t he probabilities of various outcomes. Since each simu -

lation r un can be classified as producing the problem-defining behavior or 

not, the parameter vectors leading to each result may be analyzed to see if 

140 
the original parameter distributions separate under the beh2viora l mapping. 

The degree to which such separation occurs provides a cl ue to the importance 

of each parameter in determining the overall model behavior . Hypotheses about 

the modes of operation of the carbon cycle ca n also be easily paramete rized 

and evaluated by use of this method. Thjs approach has been previously used 

in other environmental modeling applications . For example, Hornberger and 

Spear (1980) used it to model the eutrophication of a large estua ry. 

Acknowledgment 

This research was supported by a CSIRO Postdoctoral Studentship. 

141 
6. INTERNATIONAL ACTIVITIES 

On 19-23 January 1981, J. DeLuisi traveled to the Institute of Geophysics, 

University of Nexico, under the auspices of Wl'1O to me et with 1. Galindo and 

two graduate students to establis h a research project with the Dobson spectrophotometer owned and opera ted by the institute. The exceptional urban pollution conditions at Nexico City will affect Umkehr measu rements, and significant amounts of CO 2 ca n affect measurements of total ozone. A research procedure was outlined to investigate both of these problems. While at the institute, DeLuisi gave an invited seminar entitl ed IIChemical, Physical, and 

Optical Characteristics of the Nt. St. Helens Dust Cloud." 

Sponsored by the U. S .-U .S.S.R. Working Group VIII Commi ttee on the Environment, a meeting was he ld between U. S.S.R. representatives V. Binenko and 

V. Zhulev and U.S. representatives J. DeLuisi, K. Hanson, B. Herman, V. No hnen, G. D. Robinson, and V. Ramanathan to formulate the contents of the proposed U.S.-U . S.S.R. monograph on an assessment of aerosol research and climatic implications. The meeting was hosted by GNCC at Boulder on 11-13 February 

1981. The U.S. chi ef editor designated for the task is G. D. Robinson. A 

provisional table of contents was written and recommendations were made for 

authors of the various sections. The table of contents and a meeting protocol 

were sent to all persons who were considered to ha ve an interest in the project. This information is available upon request to either G. D. Robinson 

(Center for Environment and Nan, Hartford, Conn.) or J. J. DeLuisi (G~lCC, 

Bould er, Colo.) 

Nine tanks of CO 2 -in-air calibration, working, and zero gases were provided to the Nain Geophysical Observatory in Leningrad, U.S.S.R ., in March 

1981 under t he auspices of the U. S .-U.S .S .R. Working Group VIII Committee on 

the Environment. The gases will enable our Soviet colleagues to emb ark on 

atmospheric sampling and analysis programs that will yield results compa tible 

with those obtained by GNCC. Previous l y, training in CO 2 sampling and 

analysis had been provided to A. Shashkov of the ~lain Geophysical Observatory. 

A new CO 2 flask sampling station , Ocean Station N (66°N, 02°E) operated 

by the Norwegian Neteorological Institute, was incorporated during 1981 into 

the GNCC global CO 2 station network. 

GNCC was designated by WNO in 1981 as the Central Laboratory for Dob son 

Ozone Spectrophotometers. Primary functions of this laboratory a re to maintain the calibration of World Standard Dobson Instrument no. 83, and to repair 

and calibrate other domestic and foreign spectrophotometers. During 1981, two 

foreign spec trophotometers were reconditioned and calibrated, namely, instrument no. 64 from Potsdam, G.D.R., and instrument no. 41 from Bracknell, U.K. 

J. Peterson and W. Komhyr traveled to Switzerland to attend two Wl'10-

sponsored meetings on CO 2 research, 6-19 Septembe r 1981. The 10 /UNE /ICSU 

Meeting on Instruments, Standardization, and Measurement Techniques for 

Atmospheric CO 2 was convened at Wl'10 headquarters in Geneva on 8- 11 September. 

In attendance was a small group of scientists from several countries directly 

involved in CO 2 measurement programs. The purpose was to develop recommendations for the international CO 2 measurement program, which is loosely organi zed through the WNO Background Air Pollution Nonitoring Network (BAPNoN). 

On 14-18 September, the WNO/ICSU/UNEP Scientific Conference on Analysis and 

Interpretation of Atmospheric CO 2 Data convened at the University of Bern. 

142 
This was a conventional scientif ic confe rence, but with much discussion following most of the prese ntations . Abou t 65 sc ientists from 19 countries attended. \Y. Komhyr talked on GNCC fla s k data , and J. Peterson gave a paper on 

data from BR\y and Cold Bay, Alas ka. D. Gille tte, B. Halter, R. Schnell, and 

G. Herbert also had papers i nclude d in the proceedings. 

From 6 November to 12 Decemb e r, at the request of IYNO, B. Nendonca 

visited Ecuador, Peru , Paraguay , a nd Bra zil a s a technical expert and advisor 

for \yNO on BAPfloN observatories in thos e countries . The general tasks accomplished were to ( I ) assess t he st a tus of the BAPNoN observatories in each 

country; (2) offe r t echni ca l e xpe rtise and advice when needed; (3) install, 

repair, and modify BAPNoN i nstrumentation when possible and as needed; (4) 

instruct on the proper opera tion of the instrumentation and on proper data 

collection procedures; and (5 ) repo rt ba ck to IYNO and make recommendations 

when wa rranted. 

143 
7 . PUBLICATIONS AND PRESENTATIONS BY GMCC STAFF, 1981 

Bodhaine, B. A. Nuclei monitoring at baseline sites: Barrow, Alaska; Mauna 

Loa, Hawaii; American Samoa; and South Pole . Atmospheric Aerosols and 

Nuclei, Proceedings of the Ninth International Conference on Atmospheric 

Aeroso ls, Condensation, and Ice Nuclei, Galway, Ireland, 21-27 September 

1977, Galway University Press, 244-248. 

Bodhaine, B. A., and J. C. 

ments at South Pole. 

Bortniak. Four wavelength nephelometer measureGeophys. Res. Lett. 8(5):539-542. 

Bodhaine, B. A. , J. H. Harris, and G. A. Herbert. Aerosol light scattering 

and condensation nuc l e i measurements at Barrow, Alaska. Atmas. Environ. 

15(8):1375-1389. 

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

variations in aeroso l s and atmospheric transmission at Mauna Loa Observatory. J. Geophys. Res. 86(C8):7395-7398. 

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156 
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