Summary Report 1976 

U.S DEPARTMENT 

OF COMMERCE 

NATIONAL 

OCEANIC AND 

ATMOSPHERIC 

ADMINISTRATION 

ENVIRONMENTAL 

RESEARCH 

LABORATORIES 

... 

} 

• 

• 

• 

• 
Geophysical Monitoring 

for Climatic Change 

NO.5 

Summary Report 1976 

Kirby J. Hanson, Editor 

Novem ber 1977 

Boulder, Colorado 

U. S. DEPARTMENT OF COMM ERCE 

Juamta M. Kreps. Secretary 

National Oceanic and Atmosphenc Adm;n"stration 

Richard A. Frank, Administrator 

Envlronrne'1tal Research Laboratories 

Wilmot Hess. Director 
NOTICE 

Mention of a commercia l comp any o r product does n ot 

co nstitute an endorsement by NOM Envi ro runen tal Resear ch 

Labora t ories. Use for p ubli city or a dvertising purpose s 

of i nformation from t h is publica ti o n con cerning proprietary produ cts or the tests of s u c h produ cts is n ot 

authori zed. 
CONTENTS 

DEDICATION 

FOREWORD 

ACRONYl'lS AND ABBREVI ATIONS 

1. 

2. 

3. 

S \Jl'!l1AR Y 

OBSERVATORY FACILITIES 

2 . I Mauna Loa 

2 . 2 Barrow 

2 . 3 South Pole 

2. 4 Samoa 

2 . 5 Boulder 

OBSERVATORY PROGRAMS 

3. I Mauna Loa 

3.2 Ba now 

3 .3 South Pole 

3. 4 Samoa 

Gases 

Aerosols 

3 .4. 1 

3 .4.2 

3 .4.3 

3 . 4.4 

3. 4. 5 

3. 4 .6 

Solar Radiati on 

Meteorology Measurements 

Pre c ipitation Co llec t io n 

Cooperative Program 

3.5 Boulder 

3 .5. I 

3 .5.2 

3.5.3 

3 .5.4 

3.5 .5 

3 . 5.6 

3 . 5. 7 

Total Ozone 

Ery themal Irr adia nc e 

Sola r Radiation 

Atmospheri c Turbidity 

Sur fa c e Ozone 

Carbon Diox i de 

Freon-II 

iii 

Page 

vii 

ix 

x 

I 

2 

2 

3 

4 

4 

4 

5 

5 

6 

8 

10 

10 

12 

12 

13 

13 

14 

15 

15 

15 

15 

15 

16 

16 

16 
4. 

5. 

6. 

GMCC MEASUREMENT PROGRAMS 

4. 1 Meas ur ement of Gases 

4. I. I 

4 . I. 2 

4. I. 3 

4. I. 4 

Carbon Dioxide 

Tota l Ozone 

Sur face Ozone 

Halocarbons 

4.2 Strat os pher ic Aer oso l Measure me nts Using Lidar 

4 .3 Surface Aero sol Measur eme nts 

4.3.1 

4.3. 2 

4. 3 .3 

4. 3 .4 

4. 3 .5 

Mauna Loa 

Ba rrow 

Sa moa 

South Pole 

Cooperative Pro gram 

4.4 Meteo rolog ica l Me asurements 

4.4.1 

4.4 .2 

4.4 .3 

4.4.4 

4.4.5 

4.4.6 

Met eorologica l Sens or s 

Mauna Loa Met eo rology 

Barrow Met eor ology 

Samoa Meteorol ogy 

South Pole Meteorol ogy 

GMCC Trajec tory Program 

4.5 So lar Radia tion 

4. 5. 1 

4.5. 2 

4. 5.3 

4.5.4 

4.5. 5 

Me asurement Program 

Da ta Acquisition 

Quality Control 

Quali ty Con trol Through Ins trument 

Int ercomparisons - 1976 

Pre liminary Dat a 1976 

4.6 Pre cipitati on Chemis try Measure me nts 

4.6. 1 

4.6.2 

4.6.3 

4 .6. 4 

Bas eline Precipitation Chemistry 

Regional Precipitation Chemistry 

Spec ial Study 

Program Plans 

COOPERATIVE PROGRAM 

DATA liANAGENINT 

6.1 Data Acquisi t ion 

6. I. I 

6. I .2 

Hardware Considera tions 

So ftwar e Modifi cations 

6.2 Data Reduc tion 

6.3 Pr ocessing 

6.4. Archiving 

iv 

16 

16 

16 

18 

22 

26 

29 

33 

36 

43 

46 

47 

51 

51 

5 1 

52 

55 

56 

58 

60 

61 

61 

61 

62 

67 

74 

79 

79 

83 

83 

83 

84 

85 

85 

85 

85 

86 

87 

87 
7. 

8. 

9. 

RESEARCH PUBLICATIONS 

REFERENCES 

GEOPHYSI CAL ~JONITORING STAFF 

APPE NDIX A: Works hop Revie,,' 

APPENDIX B: Spectral Turbidity Stud ies at Mauna Loa 

v 

89 

90 

91 

92 

107 

Donald Pack served as the first 

Director of the Geophysical Monitoring for Climatic Change (GHCC) 

program from 197 1 to 1975 and was 

instrumental in establishing moni -

toring programs at four remot e 

l ocations to d etermi n e the glob al 

backg ro und levels of certain atmo -

spheric trace constituents, some -

time s cal l ed global "p ollutionll. In 

the early 1970 's, the need for this 

monitoring was pointed o ut by the 

S tudy of Critical Enviro nmenta l 

Problems (1970), the Study of Han's 

Imp act on Climate (1971), and the 

Stockholm Conference (1974). Hr. 

Pack's unique contribution wa s to 

d evelop within the National Ocea ni c 

and Atmospheric Administration 

(NOAA) a timely response to thi s 

need. Thanks to h is foresight and 

hard work, the globa l background 

monitoring e ffort was establis hed 

early, o n firm ground. We are 

i ndebted t o him for hi s l eade rship. 

vii 

It is possible foT' the seCT'ets of >1atUl'e ta be hidden 

in a f l ooa 0,'" cr::ta as wen as in lla t UT'e , Clearl y , we 

need i nforma t ion more tha;';. :..)e need data . 

VeP>1e T' Suomi 

FOREWORD 

From Prof . Suomi have come many memo rable quotatio n s, but t he 

one given above (Suomi , ]977 ) is particularly appropriate t o o ur 

work. 

Eac h year a nlmber of i mportant factors are co n s idered in 

deciding o n GMCC programs: 

Th e needs of climate mo delers for GMCC info rmati o n t o develop 

a nd validate their mode ls. 

The degree of a cc ur acy and spatial res o lutio n with which the 

technology nlu st b e applied to obtain data s uitabl e to achieve 

understanding of the role of e xternal causal fact ors in 

climatic cha n ge. 

The needs o f the u ser commun ity for t h e r es ultant data, and 

the most useful forms for th e data. 

The periods o f time over whi ch mo n itoring of different variables s h o uld continue. 

Th e r e sou rces available for monitoring programs. 

In the real wo rld where we ca nn o t mo nitor everything , e ve rywhere, all o f the t i me , we mu st d e pend on a clear definitio n of 

the needs of climate modelers. But as Prof. Suomi has p o int ed o ut 

(in the referenc e above) what the c limate mo delers need and what 

the technologists can provide may not be the sa me; each group must 

make the effort to understa nd the o the r' s area. Only if effective 

dialog, debate) and negotiatio n go on between the two group s will 

there evolv e a monitoring plan that meets the need s for climate 

prediction and yet is held within the bound s of available re -

sou rces. This is the c ha llenge that we re cognize t oda y, o n e that 

no doubt will remain until the c limate predi ction problem eve n tu -

ally is ma s tered. We are indebte d to Prof. Suomi f or illuminating 

thi s challe ng e. 

ix 

Kirby J. Hanson 

Boulde r, Color ado 

Oc t o b e r 7, 19 77 
ARL 

BOSS 

CCN 

CPU 

CSIRO 

DAS 

DOY 

ECC 

EPA 

ERDA 

ERL 

GATE 

G.E. 

GMCC 

GMT 

GSA 

HASL 

ICDAS 

I NSTAAR 

IPC IV 

IPS 

LED 

LST 

MLO 

NASA 

NARL 

NBS 

NIP 

NOAA 

NSF 

NWS 

PSRB 

UNOR 

URAS 

USGS 

WMO 

WPL 

ACRONYMS AND ABBREVIATIONS 

Air Resources Laboratories 

BASIC Operating Software System 

cloud co ndensation nucleus 

central processing unit 

Commonwealth Scientific and Industrial Research Organization 

data acquisiton system 

day of year 

electrochemical concentration cell 

Environmental Protection Agency 

Energy Research and Development Administration 

Environmental Research Laboratories 

GARP Atlantic Tropical Experiment 

General Electric 

Geophysical Monitoring for Climatic Change 

Greenwich Mean Time 

General Services Administration 

Health and Safety Laboratory 

Instrument Controlled Data Acquisition System 

Institute of Arctic and Alpine Research 

International Pyrheliometer Comparison lV 

International Pyrheliometric Scale 

light-emitting diode 

Local Standard Time 

Mauna Loa Observatory 

National Aeronautics and Space AdministratioQ 

Naval Artic Research Laboratory 

National Bureau of Standards 

normal incidence pyrheliometer 

National Oceanic and Atmospheric Administration 

National Science Foundation 

National Weather Service 

Physical Science Research Building (Boulder, Colo.) 

(a German-made infrared gas analyzer) 

(a German-made infrared gas analyzer) 

U.S . Geophysical Survey 

World Meteorological Organization 

Wave Propagation Laboratory 

x 
GEOPHYSICAL nONITORING FOR CLIMATIC CHANGE 

NO.5 

SutfrffiRY REPORT - 19 76 

1. SutfrffiRY 

A sampl i ng prog ram for carbon d ioxid e (C0 2 ) and Freon-II was initi -

ated at Niwot Ridge, Co l orado, at an altitude of 3.6 ~l. This is reqarded as represe ntative of mi dco ntinent , midlatitude clea n air. The 

qua lity of data is comp arab le wi th that obtained at tIle baseline s tations. The CO 2 samp ling resumes at this loca tion aft er a 23-month 

break. 

A CO 2 sampl ing progr am was reinitiated a t Key Biscayne, Florida, 

after a b rea k of 20 months. Sampl i ng is obtained by fl asks only under 

well e stablis hed trade wind co nditions. 

Increased control of parameters in chroma tograph ic analysis has 

greatly reduced the scatter in the Freon -II meas urement a t the baseline 

s tations , be ginni ng in May 1976. Thi s will allow much grea ter co nfidence i n determining zonal grad ien ts, trends, a nd annual cycles. 

A tropi cal disturbance pas sed over Samoa on December 11, 197 6 , 

ca using the Uni versit y of Rhode Island sampling tower to collap se. No 

other significant d amage wa s sustain ed. 

Use of t he und er-snow clean air s ampl ing facility at the South Pole 

was discontinued in t h e austral summer of 1976- 77 , and the GMC C mon ito ring program was mov ed to a n ewly constructed building above the snow 

surface. The building was provi ded by the Nat ional Science Foundati on 

(NSF). 

An ion chromatograph was added t o t he GMCC program On the isla nd of 

Hawaii for analysis of all major ions in precipitation c hemist ry samples. Sampl ing is limi ted to the i sland . 

Ther e was some ev idence dur ing 1976 t h at activities on Alaska' s 

n orth slope have decreased the sector from which clea n air meas ur eme nts 

can be obtained at the Barrow Observatory. The ev idence is fr om measure ments of n ea r-surfac e aerosols. 

Ther e h ave been some pe riods in 1976 at t he Mauna Loa Observatory 

(~lLO) when unusually high CO 2 co ncen trations have bee n ob served with 

downslope wind s --wind s that u sually provide stable background CO 2 

co ncen trati ons . An effort is being mad e to de termine t h e source of 

t hese anomalies. 

A wor k s hop ileld in Boulder is reviewed in Append ix A. 
Figure 1. Aerial vierl of Mauna Loa Observatory in 1958. 

2. OBSERVATORY FACILITIES 

2.1 Mauna Loa 

In August 1976, the Hilo offices of l1LO were transferred from the 

University of Hawaii campus to the Federal Building, Rooms 202 and 203, 

in downtown Hilo (mailing address: Mauna Loa Ob servatory, P.O. Box 275, 

Hilo, HI 96720; phone: 808-961-3788) . 

The new facilities provide more offi c e space, as well as separate 

ele c tronics and chemistry laboratories in the basement of the building. 

Some remodeling of the laboratory areas was necessary to satisfy observatory requirements. The modifications, carried out by the General 

Services Administration (GSA), included installing extra outlets, air 

conditioning, laboratory benches, new lighting, a venrilation hood, and 

other equipment needed for electronic and chemistry work. All these 

changes sho uld be comFleted by early 1977. The trailer at Cape Kumukahi, which was formerly used as a research facility, has been sold 

through the GSA. 

In July 1976, MLO celebrated its twentieth year since opening the 

main building. Figure 1 shows the observatory in 1958. Contrast this 

picture with Figure 2, taken in 1976. 

2 
Figure 2. Aerial view o f Mauna Loa Obs e rvatory in May 1976. (Photo 

by J. P. Lockwoo d, USGS Hawaii Volcanoes Observatory.) 

2.2 Barrow 

A six-pair s hielded cable was installed from the observatory to the 

Air Force hangar at the Naval Arctic Research Laboratory (NARL) which 

hous es the commer c ial telephone terminal for Barrow. The cable was laid 

on the ground parallel to the road and was marked with red flags along 

its length for access and protection during the winter months. Two 

telephone s us ing this cable, a commercial phone and a lo c al, three-digit 

phone, wer e installed at the station. In addition, on e pair was made 

availabl e to the U. S. Geological Survey (USGS) magne ti c observatory t o 

provide telephone s ervi c e to their in s truments, whi c h are located near 

the Barrow station. 

A glass still was installed in the observat o ry to provide pure 

water for the pre c ipitation chemi s try program. 

The GHCC married quart e rs at NARL were improved by adding a 

16' x 22' wa nigan, which nearly doubled the living space. The interior 

of the exis ting quonset hut wa s remodeled) a nd new furniture was purchased. 

The s tation was plagued by vehi c le problems throughout 1976. The 

USGS vehicle at Barrow was borrowed in the fall to ensure continuou s 

tran sportation through the winter months . 

3 
2.3 South Pole 

The temporary under-s now clea n ai r faci lity was us ed for its fina l 

yea r in 19 76. Plans of GMCC and NSF were we ll underway for t he 1976 - 77 

austral s ummer co nstruction of a more permanent elevated facility almos t 

directly grid north of the temporary faci lity. 

Durin g the 1975-76 austra l summe r, a l ea king roof a nd snow loading 

fro m l ocal drifting continued t o threa ten the struc tural well-bei ng of 

t he facility. Tw o s upport beams were ad ded, and aIm ve rti cal e xtension was added t o the main and emergency ha tches. To h elp redu ce melting fr om the ce iling, room temperatu re was r educed to approximately 

15 °C. 

A 2 -mon th s urfa ce ozone and ae ros ol sampling program \.,tas ca rried 

out on the top floo r of the sky labo ra tory. This was intended t o assess 

Skyl ab's su itability as a ce ntral mo nitoring l ocation in the event that 

the GMCC program had to be moved. because of the deteriorating physi cal 

conditiorl of the temporary c lean air facility. 

2.4 Samoa 

There were no cha nges in the Samoa Observatory d u ring 1976 except 

for the add ition of a remote sampling building in Novemb er. Th is 

con siste d of a prefabrica ted 8 ' x 16' buildin g purchase d from Elder 

In ternati o nal. It wa s ere cted at the east e nd o f Lauagae Ridge and wil l 

be adjacent to t h e Sa moa remo t e samp ling tower, to be built in early 

1977. The bu ilding i s air conditione d and will b e u sed to house t he 

Samoa aeroso l equipment cons isting of the General Electric (G.E.) 

co nden sa tion nu cleus coun ter and ne p he l ometer , a Pollak co un ter and 

poss ibl y a surface ozone co unter. Air will be sampled a t approximately 

t he 50-ft le vel and brou g h t to the inst ruments to a gas aerosol sampl ing 

stack de signed by the GMCC Tec hniques and Standards Group . 

2.5 Bould er 

Tv.'O observatory facil ities in Boulder a nd vicinity are ava ilable t o 

the GMCC program. One con sists of platform s pa ce on the roof o f the 

Un i versity of Color ado Phys i ca l Science Resea rch Build ing (PSRB) No . 3, 

headquarters o f the GMCC program. Th is roof space is especially su ited 

for exposure of s olar r adiati on meas uring instrumentation, and co ntai n s 

a n Ash dome o b servation shelter housi ng a Carson As tronomical Instruments solar tracker . The second faCility is loca ted at NOAA ' s Fri tz 

Peak Observato ry wh ic h i s opera ted by the Environme ntal Research Laboratorie s! (ERL) Aeronomy Laborato ry. This obs erva t ory is a bout 40 km 

west o f Boulder a t an el evati on of 2.4 ~n above mean s ea leve l. (Fritz 

Peak rises to a n altit ude of 2.7 km.) The site is espe cia lly s u ited for 

te sting and operating gas a nalysis instrume nta tion s in ce clea n air is 

4 
predominantly available there, even in spite of heavy traffic passing 

near the observatory, especially on sWTUTlertime weekend s. Prevailing 

winds at the observatory are from the west, the dire ction of the Rocky 

Mountain Great Divide. 

Niwot Ridge, at an elevation of 3.6 km near the Great Divide, is 

also a GMCC monitoring s ite. Air samples for CO 2 and Freon-II analyses 

are coll ected once a week there under contractual arrangements with the 

University of Colorado Institute of Arctic and Alpine Resear ch (INSTAAR). 

This high altitude location is regarded as a mid continent clean air 

site. Data from here are often comparable in quality with data obtained 

at the GMCC baseline statio n s. 

3. OBSERVATORY PROGRAMS 

3. 1 ~laun a Loa 

Two special short-term programs were carried out at MLO. Glenn 

Shaw, of the University of Ala ska, installed his narrow-band sun photometer in MarCh, and measurements were made through November (see Appendix 

for further description). A 2-month (June-July) intercalibration of 

Dobson spectrophotometers, u sing the world standard Dobson No. 83 and 

the MLO Dobson No. 63, was performed by student aides Steve Hina and 

Gary Brown, who took a series of concurrent total ozone measurements. 

The program compacing the GNCC URAS-2/Scripps Applied Physi cs CO 2 

analyzer systems is still in effe ct . In addition, weekly CO 2 fla sk 

samples have been taken through the URAS-2 since June, and the manually 

operate d weekly CO 2 flask program was reinstated at Cape Kumukahi in 

Na cch. 

In accordance with the U.S.-U.S.S.R. bilatecal pcogcam o n the 

protection of the enVironment, Anatoli Yeliseyev and Vlad imir Kovalov of 

the Geophy sica l Observatory of Leningrad visited HLO for about 3 weeks 

in October . The scientists brought with them the H83, the device used 

in the USSR to measure total ozone in the atmosphere. They spent mo re 

than 20 days at the observa tory making total ozone meas urements with the 

H8 3 and comparing their data with concurrent MLO Dobson spectrophotometer readings (Fig. 3). The results showed that the two instruments 

agreed within 5%. Drs. Yeliseyev and Kovalov also had the opportunity 

to observe all the other measurement programs at HLO. 

During the latter part of the year, the data acquisition system 

(DAS) suffered a major outage, possibly due to hardware or environmental 

causes. Since December, meas urements from all systems ha ve been kept on 

backup recorders. Becau se of the outage, only the National Weather 

Service (~,S) nocmal incidence pycheliometer (NIP), the quactz pyranomete r, and the first quartz channel of the I3-channel radiome ter could be 

5 
Figure 3 . Drs. Yeliseyevand Kovalov r Geophysical Observatory of 

Leni ngrad, check ozone measurements on the M83 at Nauna Loa . 

recorded continuously. In October, a filter wheel pyrhel iometer was 

install ed which requires manual measur ement and recording of data. To 

prevent f urther interruptions due to DAS failure, a separate NOVA II 

computer is now being used for the lidar system. 

An ion chromatograph, which a llows measurement of all ma jor ions in 

precipitation chemistry samples, was acquired for the new MLO chemistry 

laboratory in December. 

The following programs were dis continued during 1976: solar 

aureole; rain S r 90; and aerosol particles f o r analysis from the Commonwealth Scientific and Industrial Research Organization (CSIRO), Au s tralia. 

Maun a Loa programs operated during 1976 are listed in Table 1. 

3.2 Barrow 

The Instrument Co ntrolled Data Acquisition System (ICDAS) was 

inoperative during the first 2 months of 1976 becuase of problems with 

the Waagco magnetic tape drive alignment. 

6 
Table 1. Summary of Sar.lpl i ng Programs a t t1auna Loa in 1976 

M.:I"i tor irg ProgralU 

Gases 

---cart!')" lIio ~lde 

To tal OlOne 

f 1 t.!)r ocd l'bons. 

AHo~ols 

ittrr.os;>r er ic lurl itlll .. t •• 

( r.c iShl -d i st rfbu t ion) 

( crct: nu t ion "1I(l e i 

Opt i c. 1 prooerties 

S.J! ar Radialio" '~ :)! l spectral 

;r r,tlJiance 

DI r e ct s pectr a l 

i rl',ld i anc e 

Woll e r vapor 

So l dr a ureo le 

HelfOrology 

f empera lure/dewpo i nl 

PreHu re 

Prec i pltat ion 

Preci pi lalion 

e ne,.. i st ry· -GHCC 

'il iods 

Cirrus clouds 

COOE,! r.n\Yf Proqr<1Cls 

Ca rbon lroonoJli de--HdJC 

P I dock l nst i lule 

50°2 , tf0 2--EPA 

To tal su rf ace panicu l aLes- -EROA 

Tur b i d i ly- - EPA 

PreCI p it ati on Chem iS l ry -- EPA 

Ra i n Sr!lo ' - EROA 

Ae roso l par U e! es for 

ana lys is- - CSJRO 

Su rl ace i r illulI- -Uni vl!rs ity o f 

l1'ami 

So h I' Rac i llol i on 

[ ".)'l h(! q.l pett"'.ill-~ 

Tel"ol e l.ll;"P f Si ty 

AtlllOspneric e l ec trid t y--APCL- ERl 

Preci pita tion che.TI islr y-- EROA 

Turoid; ty- - AFGL 

Instru:nen l 

Evacua t ed glass f' ask (S IO) 

App l i ed Physic s in f r ared 

gas ana lYl er (S IO) 

URAS - 2 Illf r ared gas ana l yzer 

Evacuat ed g l ass fl as k (GMCC) 

ElectrochelJll(.' «lnc en t r at icn cell (fCC ) 

tl ~loi olone !lIeter 

Dob son pe ro p~ol ome r 

Evacu dled f la s k 

l idar 

Ga rdner couMer 

G, [ , co..,nter 

Po l l ak. COllnter 

Fcu r-Itavelength nephelomete r 

Ul t r a", tet radiolleter 

Fou r Eppl ey py an~ters 

Epp l ey ou lt:- type pyranOlDe t er 

Eppl ey norma l i ncidence 

py r ne l io .. e t e r 

F It e r whee l pyr he liome l er 

Hu l li-cnanne l py r M l i ome ter 

Fos ke lt 

Aureol e came ra 

Hydro t hermo9raph/the rm i s t a r 

Barograph/pressure t ransdLc e r 

8 inch r a in !;ILlge 

r ipp ing buc'e t ga ge 

pH er, br idge, 

e lec trodes 

Anel80lIIeler 

l idar 

Chemica l reaction wi t h HgO 

ClIt>lfIi ca ' bu bb ler ~yS tem 

Hj 'vol'llme f iaer 

D' ... d l .... ave lengtn s unp ho torne l er 

Hi sco co II~ ct r 

t::ln exchange COI\l110 

Impa c t or / prec ip i ta t o O' 

Mol ec ula r sieve 

Ul tr'aviole t meter 

El ec tncal Hnsors 

HASl coHectors 

Vol : lllfill gi'l l photometer 

7 

Sampling Fr e quency 

21mont h 

Cont nuou~ 

Cont inuous 

l / week 

Continuous 

Con t inuous 

Dis c rete 

l/week. 

1/"'ee \ 

Disc re t e 

CO'lt lnuou s 

Discrete 

Cant inuous 

Cant inuous 

Contitl uous 

Contin uous 

Cant inuous 

01 Jc r e te 

ontlnua1i~ 

Ca nt inu:)u s 

l / .... eek 

Conl j fiuOI)S 

Cont ' nI.O'U's 

Oa i 11 

Cont illuo us 

Oi H rl! te 

Cont inuous 

l / wee k 

Ca nt inuou$ 

1/2 weeks 

Inte rm~ nt 

Di scret e 

Disc re t e 

l!lIlonth 

Dis c re t e 

Co~ inuous 

Conti nuous 

Oi scr e te 

OJ "cret e 

OCita reco rd 

OCl 1958 

OCl 1'355 

Jun 1974 

Jun 1976 

Drese nt 

ore s ent 

tlre sent 

pres ent 

Sep 197) present 

Jut 19;5 pl'e se nl 

Oc t 1957 prese nl 

Sep 197) pres en l 

Ap,- 1913 presen l 

Sep I S6} 

Sea 1913 

J ... l I S? ) 

Jar> 19}4 

Apr 191 2 

Hay 1912 

Jan 19~8 

p,'e sen l 

present 

pr esen t 

pr eSenl 

present 

nt 

Sep 1975 

Nov 1976 presen t 

May 1972 pr esenL 

Ju I 1967 p res ent 

Jun 1974 p rl!sent 

1955 pres ent 

1955 pr es ent 

Dec 1956 pr es ent 

Dec 1956 pr esent 

Oct 1974 presen t 

Dec 1956 ore sent 

Ap r 1973 present 

Aug 197] pr esen t 

Aug 1971 present 

1970' s present 

1960 ' s present 

Ma r 1973 presen t 

No" 1955 Apr 1916 

Aug 1971 No v 1976 

Aug 1911 prese n t 

Dec 197] pre sent 

DCl 1975 p resent 

Ap r 1976 presen t 

Aug 197 5 p resent 
A G.E. aerosol counter and a fo ur-wavelength nephelometer were 

installed i n May 19 76. The nephelometer was inoperable from Au gu st 3 to 

the end of the year and had to be return ed to the manufacturer for 

repair and mod ification of the coo ling system. A Royco particle co unter 

was put in operati o n in July. 

The CO 2 UNOR analyzer was 

prob l em with the old a n alyzer. 

direc t co ntrol by the ICDAS. 

replaced o n Augus t 2 because of a "no i se 11 

The CO 2 system wa s modified to provide 

Th e relative humidi ty sen sor was deactivated and repla c ed by the 

dew point temperature sensor in channelS of the ICDAS data array . A 

s ummary of the sampling programs is give n in Table 2. 

Several coop e rative programs were s upported during 1976. In 

September, Kennet h Rahn, University of Rhode I sland, installed a wind 

controlled aerosol sampling system, under an Office of Naval Resear c h 

contract t o st udy the Arctic haze layer . A s p ecial SF6 flask sampling 

program was conducted for the Energy Research and Development Adminis -

tration. The 19 76 National Aeronautics and Space Administration (NASA) 

Latitude Survey was supported by GMCC ground-based measureme nts. 

Stat ion p erso nnel assisted in erec t i ng a llWyoming shield ' 1 precipitation 

co llector, approximately 200 m no rth-northwest of the station, f or Carl 

Benson, University of Alaska. The collec tor is designed to minimize the 

effects of blowing snow on precipitation collection. The Smithso n ia n 

Radiation Biology Labora tory installed a new data acquisition system for 

its solar radiation ins trwnentation . Data are now digiti zed and stored 

on magnetic c asset te t apes. 

The University of Nevada Desert Research Institute high-volume 

sa mpl i ng prog ram was dis cont i nued during 19 76 because of equipment 

failure. The Environmental Protection Agency (EPA) liM isco 11 automatic 

preCipitation collector was discontinued early in 1976 because of de sign 

problems. 

3.3 South Pole 

The n ew execu tive program, BASIC Operating Software System (BOSS) 

751 70, was installe d and started operating i n earl y January 1976. The 

system performe d s atisfactorily until Septembe r , when an integra ted 

circuit on the central processing unit (CPU) board faile d. As a res ult 

ICDAS was down until the arrival of a new CPU board o n November 21, 

1976 . 

A n ew me teorological system was added in Janua ry 1976. Mea s urements included air and snow s urface temperature, ba rometric pressure, 

and wind speed and directio n. The s i gnals for thes e measurements were 

processed throug h individual trans lators a nd then were recorded by 

ICDAS. 

8 
Table 2. 

Hon i t Qd fl9 Programs 

GiI~('S 

-----carbon dio.>:10e 

lota olone 

rf i! ce Olone 

F 1 uOl'ocarbons 

AerO iO 1 i. 

Conaensa t ion nue le i 

So l a r Radi al ion 

Glo bal s pecl."a I 

i r l'ad ianc e 

l~eLe \l rol o9Y 

f empe ra lure 

Oewpoi nL temperature 

Pre ssuI' e 

Preci pitation 

Snow cover 

'.l i n(! '> peed/dire ction 

Ai( d1d gr ound 

te~Derd tur es 

Re l a t ' ve ·;. ' .:i t y 

Pressu" e 

Coopera~; ~e Programs 

urb ~~ 'r-EROA 

Pr eci;;i talion chemistry- - EPA 

Su rface globa l r adi -

at ion--SRBl 

Tota l $ •. rface 

pa r\. ' culates--DRI 

(02 sar~ ing--Scripps 

lotal surfac e 

pi! r t ; Cl. I a te s- - ERDA 

Tol al tl0Z--itercnomy 

l at>. NOM 

Io t a I s urface part icu ' 

late s ~tt elementa l 

ana lys i , · · tI'n 

Summary of Sampling Programs at Barrow in 1976 

Ins trument 

UIlOR infrar ed 9.H. ana l yz er 

Eyacuated g lass fl ask. 

Oobson ~peclropho~ometer 

ECC 

Od si bi DI one mete r 

Evacuilted fl ask 

Gardner cou nter 

G. E. ( ":1densat ion nucleus 

(aU 1 !.e r 

P(. \l ak counter 

-A ne l-' helomel e r 

four Epp ley pyranometers 

U1tr'a',lio let radiometer 

Hyg ro t herll10ljraph 

Hygrothermogra ph 

Hie robal'Ggraph 

6-inch rain gage 

Obs e rver 

Bendi x ae ro~ane 

Remote sensors (the rmi s t ors) 

RemO le sen sor 

I r ansduc er 

Oua' ~av elength ~un photome ter 

Mi sco co ll ector 

f p tl1 ey pyrlll)ome l en 

Scanni ng !IV r-aai O!!le te r 

Hi- volume ~ampler 

Evacua ted r 1 asl( 

Hi-volume sampler 

NOZ spectrome t er 

Hi - volume samp ler 

9 

S~mp' i ng Frequ ency 

Continuous 

l/week. 

Oi screte 

Continuou s 

Continuou s 

l!wee~ 

Disc rete 

Cont inuo us 

Oiscrete 

Con 1 i nuous 

Continuous 

COllt i nuQU 5 

Continuous 

Cent i nUDus 

Con t i nuous 

Discrete 

Dis cre te 

Cont inuous 

Cont inuouS 

(on t i nuous 

Continuous 

Di screte 

OiscnH e 

Cont i IItM1 US 

Cont il\tlous 

Continuou s 

Z/BO 'l th 

Cont inuous 

Disc ret e 

Di scre t e 

Data record 

Ma r 197 3 

Apr 1971 

Aug 1973 

Mdr 1973 

Ju l 1975 

Sep 1973 

Se p 197 1 

!-lilY 1973 

HilY 1976 

Oc t 1975 

Hay 1976 

Jun 19 ~ 

Jun 1974 

present 

present 

present 

pre sent 

pr ese nt 

pre s enl 

pr'esent 

Nov 1974 and 

pres ent 

po"e se nl 

Aug 1976 

pres ent 

pr esenl 

feb 1973 Jan 1976 

Feb 1973 pres ent 

feb 1973 pre s ent 

feb 1973 Jan 1976 

Oc t 1974 present 

Feb 1973 present 

Nov 1975 present 

Nov 1975 Oec 1976 

Ilov 1975 present 

Mar 1973 present 

Sep 1973 Sep 1975 

Apr 1973 present 

l1ilY 1975 present 

Oct 1973 Aug 1976 

Jan 197 4 present 

Aug 1975 present 

Aug 19 75 pre sent 

Sep 1976 - pre5 ent 
After only a year of use at the South Pole, the multicha nnel radiometer progr am was disconti nued in February 19 76 beca use the fogging 

window p roblem could not be co rre cted. The inst r ument wa s sent back to 

Bo ul der in Novemb er 1976. 

Mr . Cobb's field mill and air-Earth current antenna were relocated 

in Janua r y 19 76. The original s ite experienced extens ive local dr i fting 

that bnried the sensors. The sens ors were r eloca ted about 60 m grid 

east of the clean air f aci lity , and t h i s new si te proved to be free of 

ex ces s ive local drifting. 

New cooperative programs for GMCC in c lude d a carbon-14 sampling 

program f rom NOAA/ARL (Air Resour c es Laboratories) and an acousti c e c ho 

sounder from NOAA /WPL (Wave Propagation Laboratory). 

Table 3 sWIIDlarize s sampling prog rams at So uth Pol e Station. 

3. 4 Samoa 

The active mea s ureme nt prog rams at the Samoa observatory a re s umma r ized below. They are divided into t he fo llowi ng area s : gases, bo t h 

surface and total a tmos pheri c column; aerosols, which i n cl ude s urface 

cloud condensation nucleus (CCN ) mea s urements and turbidity monitor i ng; 

solar radiation; meteorol ogy mea s urementsj prec i pita ti on collectio n; a nd 

cooperative programs. Inc lud ed are any changes, such a s relocations, 

modifica t i ons, n ew ins tal la tions , or spec ia l proce du res . 

3 .4.1 Gases 

The following we re monitored: carbon d iox ide; surface ozone; total 

ozone ; and fluo ro carb on-ll (s urfa ce ). An N0 2 spe ct rome ter is scheduled 

f o r ins talla tion in early 1977. 

Ca r bo n dioxide 

Co ntinuous CO 2 measureme nts were made with consistent sampl i ng 

configuration du ring the entire year. A URAS-2T is used as the primary 

monitoring device and its output i s continually record ed by the station 

ICDAS. In addition, weekly fla s k samples ar e obta ined for shipment to 

Boulder where a nalyse s for compa rison purpos e s are done. During 1976 

air wa s bro ught to the URAS a na lyzer from Ca pe rla tatula by a 1100-ft 

sampling line composed of a n internal gas line of 3lB-in p o lyethylene 

tubing (continuous length, no splices). It is protected by an outer 

line of l-in d iamet er black p o lyvi nyl c hlo ride, used primarily as a light 

barrie r. The sample line inl e t wa s attache d t o the Univers ity of Rhode 

Island sampling t ower on the Ca pe. Early in 197 6 , the URAS analyzer 

floati ng-s ignal output was mo dif ied by u s ing a p reampli fier to reference 

one side of its f10 at ing signal t o a system chassis ground. Pri o r t o 

this, the high s ide o f the output had been sa tu ra ting the I CDAS digitiz er. 

10 
Table 3. Surnrnary of Sarnpling Prograrns at South Pole Station in 1976 

~on to ring Programs 

Gine s 

Carb on di oxide 

Surf ace ozo ne 

Total OlonE' 

F iuo r ocar bons 

Ae roso l !. 

CO,'1I!flsalion nuclei 

Solar Radi a tion 

r. ::~ 1 spec t ra l 

Di r ect s pe ctral 

He t eoro logy 

Air tertperature 

Sno .... s urface temperature 

Pressure 

Wi nd 'peed and d i rection 

Coopera t i vI!' Proqrams 

CO 2 sampling - -S,cr ipps 

Carbon -14--ARL 

Acoustic so under--HDAA 

Particulate sampJing--EROA 

Trac l' metal sampling--

Un i versity of Maryland 

Atmospheric electri c ity--HOM 

IonospheriC absorpt ion· · NOAA . uCSO 

"tl€f'lTIa) r adia ti on 

Tur Di dity·· ePA 

In ~trul:lent 

URAS. infrared 

analyzer '" Evacuated gas t1 ask 

El ectrOC hemical co nce ntral ion cell 

OaslD\ Ol one meter 

0( 1)50n spectropho tometer 

Sta i n l ess steel fl ask 

G £. counter 

Gardner counter 

Po l1alo: counter 

Four Epp 1 ey pyranomeUrs 

Ultraviolet radiometer 

'" 

,,",ultichannel radiometer 

Thermi s tor 

Thermisto r 

Transducer 

Bendi x aerovane 

Evacuated glass f1 ask. 

St ee I fla~la 

Tra nsmi tte r and 

rece i ver 

Hi - vOl u.,. PUl:lp and 

f il ter asser.bly 

Hi -vo lume pump and 

f I I te r assembly 

Fie ld mi II and 

dipole antenna 

30 a nd 50 llHz 

radi ollete rs 

Hoc TR radiometer 

Soo pholoneter 

Sampl i ng Freque ncy Dat a record 

Cont i nuous J.n 1975 present 

2imonth J.n 1975 pre s ent 

COnt i nuou s 0" 1971 present 

Continuous J.n 1976 pre~ent 

Oiscrete 0" 1963 present 

U .... eek Temporary 

Dec 1975 - Jan 1976 

Continuous J.n 1974 present 

Discrete Joo 1975 present 

Discrete J.n 1974 present 

Cont i nuou s dur iog f,b 1974 present 

austral surrner 

Continuous duri ng f,b 1974 present /l ustra I s unwne r 

Continuous during f,b 1974 pre s ent 

austra I sunwner 

Continuous during J" 197~ Feb 1976 

austral SiJr:-:l1er 

Conti nuous d uri ng Doc 1975 prese nt 

aus tra l sumer 

Continuous during F,b 1976 prese nt 

austral s u.'lIIIer 

Cont i nuous 0" 1975 present 

Conti nuou~ 0" 1975 present 

2/lIIOnth 1955 - present 

1/ .... eek J.n 1974 - present 

Cont i nuous Tempo rari ly d isconti nuedJan 1976 

1/ \otu k 1970 prese nt 

1/ .... 1'1'10: 1974 present 

Cont inuous Jon 1975 present 

Conti nuous 1962 present 

Cont i nuous J.n 1975 presl<nt 

Di screte 1975 present 

11 
Surface Ozone 

Two methods of surface ozone monitoring were used : the ele ctro -

c hemical concentration ce ll (ECC) meter, and the Dasibi ozone analyzer. 

An ECC meter Model No. 005-8 wa s used to monitor air in the vicinity of 

the observato ry roo f . The sample inlet was located approx imately 15 ft 

above the roof a n d a sampl e l i ne of Teflon tubing was u sed to minimi ze 

ozone destruction. Tota l inlet line length was approximatel y 30 ft . 

The Dasibi ozone analyzer wa s equipped with the same inl et configuration 

as the ECC mete r. In additi o n, both ozone instruments were calibrated 

o n a weekly basis using a McMillan ozone generator, mo dified by the GMCC 

Techniques and Standards Group in Boulder, for greater long-term stab ility. 

Total Ozo ne 

Total atmo s pheric ozon e was monitored during the entire year using 

Dob son Ozo ne spe ctrophotometer No. 42. The i ns trument is housed in an 

Ash dome on the observa t ory roof. As part of a special progr am t o 

develop correct i o n factors for the instrume nt , quasi-simultaneous 

observations were conducted du ring Apri l and May. 

F luorocarbon -I I 

Weekly flask sanlples were obtai ned throughout the year for s hipment 

to Bo ulder and s ubsequent a nalysis. The sampling fl as ks consist of 300 -

ml evacuated s t ai nle ss steel cylinders equipped with valves. 

3.4 . 2 Aerosols 

Surface ae rosols (CCN) were monitored throu gh o ut 1976 using a 

modified Gardne r counter equipped wi th a long tube and a light-emitting 

diode (LED) light source . Obse rvations were made daily at Cape Hatatula. Two other instruments we re also used during 1976: a Volz sun 

photometer, and a Vol z twiligh t p hotometer . The official observing site 

for the sun photomete r has been moved from the NWS s tation at Pago Pago 

to the GHCC observa t ory s ite. The twi l ight photometer became opera -

tional in April 1976 and i ts data records are sent directly t o Dr. Volz. 

Sun p hotometer data are sent to the National Climatic Center in Asheville, North Carolina. An addi tional aerosol sampl ing progr am ha s been 

conducted fo r the Health an d Sa fety Labo ratory (HASL). It invo l ves 

operation o f a h igh- volume air sampler installed in April, ad ja cent to 

the observatory. These sample f ilters ar e ma ile d weekly to HASL fo r 

radionuclide analy sis. 

3. 4.3 Solar Radiation 

Four hori zontal incidence Eppley pyra nometers with quartz , gre en, 

ora nge, and red filter domes comp ose the present GHCC radiation s ensor 

array in Samo a. A normal i n ciden ce pyrhe liometer ( NI P) is scheduled for 

1 2 
installation in early 1977. The four Eppley sensors were operational 

from January 11 through December. In April, Bernard Mendon ca conducted 

a special project to intercompare the Eppley sen so rs with the GMCC 

traveling standard. 

3.4.4 Meteorology Measurements 

GMCC meteorology sensors consist of the follow ing pieces of equipment: Bend ix aerovane, Mod el No. 120; surface and ground temperatu re 

sensors (thermistor sensi ng element); humidity sensors; and surface 

pressure sensors. 

Wind 

Wind and wind speed were continuously recorded using both the 

Bendix chart recorder and the G~lCC ICDAS system. The instrument is 

located on the remote sampling tO~ver on Cape Matatula. 

Temperature 

Ground a nd surface air temperatures were continuously monitored 

using linearized thermistors . The surface air temperature sensor is 

mounted in an aspirat ed radiation shield which i s attached to the 

remot e sampling tower located on Cape Matatula . 

Humidity 

Attempts at co ntinuously recording humidi ty with the ICDAS and a 

solid state sensor failed. As an interim solution, a hygrothermograph, 

located at Cape Matatula, was used during most of 19 76. Installation of 

a dew cell is scheduled for 19 77 . 

Surface Pressure 

By use of a pressure transducer as a sensor, sta tion pressur e is 

continuously recorded. In addition, a microbarograph provid es a chart 

record of pressure. Records from both the transducer and the microbarograph are compared with tho se from the station standard, a wallmounted mercurial barometer. 

3.4 .5 Precipitation Collection 

Two types of precipitation collecto rs were operational during 1976: 

the HASL wet/dry collector, and the EPA Misco collector. 

HASL Wet/Dry Collector 

Two co llectors of this type were install ed during Apr il 1976 by 

Herb ert Volchok. They are located on the instrument platforms on the 

observatory roof, and their sample containers are mailed to HASL each 

13 
month. In addition, two bulk collectors are also exposed continuously 

for HASL and returned monthly. 

EPA Misco Collector 

Previously located at the NWS station near the Pago Pago International Airport, this collector was moved to the Samoa Ob s ervatory roof 

in January 1976. The original c ollec tor developed irreparable me chanical problems and wa s repla c ed in July. All mechanical and electrical 

components in the repla c ement were coated to prevent corrosion, a 

primary c ause of the original collector's failure . Samples are mailed 

ba c k t o the United States monthly. 

3.4.6 Cooperative Programs 

Active cooperative programs during 1976 are sampling for environmental lead, sampling for trace inorganic constitue nts in maritime air, 

and operating a twilight photometer. 

Environmental Lead Sampling 

Clair Patterson, California Insti tute of Technology, collected 

environmental s ample s for lead analysis at extremely low levels. 

Sampling methods were dry depo s ition, air sampling and subsequent 

analys i s of collecti on filter, precipitation collection, and plant 

tissue collection. The two samplings were conducted during August, 

November, and December 1976. 

Trace Inorganic Constituents 

R. A. Duce, University of Rhode I s land, i s the princ ipal investigator for this program. The fa c ility on Ca pe Matatula includes a small 

prefabri c ated building that h ou s e s a c l e an b e n ch, supplies, and a 60-ft 

walkup towe r manufa c tured by Upright Sc affold Co. Primary activities 

during 1976 involved high-volume air sampling using the tower as a 

s ampling platform. Preliminary sampling, which began in January 1976, 

terminated in February. Sampling reswned in July and continued through 

September. The program suffered a major loss during December, wh e n a 

tropical storm destroyed the sampling tower. At the time of the tower' s 

destruction, winds were over 100 mph. Resumption of the pro gram i s n ow 

scheduled for 1980. 

Twilight Photometer 

This monitoring program wa s b e gun in April for Frederick Volz, and 

involves co llec tion of data conc erning s pe c tral characteristics of the 

twilight sky. Chart re c order records are mailed directly to Dr. Volz. 

14 
3.5 Boulder 

3.5.1 Total Ozo n e 

This continui ng program started iu Bould er in 1966. Measu rements 

ar e made on the roof of PSRB- 3 wit h Dobson ozone s pectrophotometer No. 

82 . Observational data are routinely pro cessed a nd results are sent to 

the Atmospheric Environment Servic e, Department of the Environment , 

Toronto, Ontario, Canada, for publication in Ozone Data for the World. 

3.5.2 Ery themal Irradia n ce 

This program was initiated in Boulder in May 1975 after s imil ar 

observations, under s ponsorship of the Climati c Impact Assessment Program, U. S. Department o f Transportation, were terminate d at Bisma rck, 

North Dakota, and Tal l a hassee, Florida . Resul ts of the Bismarck and 

Tallahassee meas u rements ha ve been s ummarized in a report submitted to 

the Department of Transp ortation. The purpose of the Boulder program is 

to continue i nvestigations, at a mode rate ly h igh altitude s tation, of 

the relations hip betwe en near gro und l eve l variati ons in so l ar ul tra -

violet radiation and changes in the t ota l amount of atmo spheric ozone. 

An additiona l goal i s to c ompare obse rved erythemal ultraviolet irradiance val ues with results deduced theoreticall y for the Boulder location . 

3 . 5.3 So lar Rad iation 

Solar rad iation observations were made pri marily to ca libra te 

pyranometers and pyrheliome ters for use at the CC base line stations. 

Pyranometers a nd pyrheliometer intercomparisons were also condu cted with 

instruments u sed in the 197 4 GARP Atlantic Tropical Experiment (GATE) 

project, as we ll as with pyranometer and pyrheliometer standards maint ained by the NOAA j ARL Solar Research FaCility. 

The Solar Re search Faci lity is in the University of Colorado 

PSRB- 3. Its prima ry respons ibility is to ma i ntain calibration standards 

and to c alibra te pyra nometers and pyrhel iometers u sed at 35 s tations 

throughout the United States. Toward the end of 1976 , t he So lar Res earch Facility began a routine monitori ng prog ram to measure total 

global rad iation, global radia tion in broad wavelengt h bands (g r eater 

than 295, 395 , 530 and 695 rum), and diffuse a nd d irec t radiation. This 

program is expected t o continue indefinitely. 

3.5.4 Atmospheric Tu rbidity 

eas rements of atmospheri c turbidity were made t h ro ugho u t 1976. A 

dual wavelength (380 and 500 rum) s un ·photomete. was employed for the 

measurements, wh ich were taken from PSRB-3 in Boulde r . 

15 
3.5.5 Surface Ozone 

The program to measure surface ozone, initiated at Fritz Peak 

Observatory in the mountains west of Boulder in 1975, continued throughout 1976. Data obtained at this relatively clean air midlati tude site 

are compared with data gathered at the GHCC stations. The ozone data 

are furthermore used by the NOAA/ERL Aeronomy Laboratory staff in their 

interpre tation of N0 2 measurements taken at the observatory. An ECC and 

a Dasibi ozone meter are used to measure the s urface ozone. 

Ozone measurements with an ECC meter also are mad e routinely at 

PSRB-3. Although the primary purpose of this instrument set up is 

observer training, the demand by various Boulder researchers for the 

data obtained has been relatively high. 

3.5.6 Carbon Dioxide 

In January 1976, a flask CO 2 sampling program was resumed near 

Boulder at Niwot Ridge, under contractual arrangeme nts with INSTAAR. 

This coope rative monitoring effo rt began in June 1969, but was interrupted from May 1973 to December 1975. Pair flask air samples are 

collected on a weekly basis at Niwot Ridge, and delivered to the GMCC 

Laboratory for CO 2 analy sis by i nfrared analyzer instrumentation. 

3.5.7 Freon-II 

Under contract ual arrangements with INSTAAR, a program to monitor 

Freon-II (CC1 3F) cOlnmenced at Niwot Ridge, Colorado, in Janu ary 1976. 

Pair air samples are collec ted in stainless steel cylinders at wee kly 

intervals, and delivered to Boulder for CCl 3F a nalysis by chromatographic means. 

4. GHCC ~ffiASUREHENT PROGRAMS 

4.1 Measurement of Gases 

4.1.1 Carbon Dioxide 

Continuous measurements of atmosph eric carbo n dioxide were mad e 

throughout the year at all GMCC stations. 

Point Barrow, Ala ska, is the only observatory continuing the use of 

the UNOR , a nondispersive infrared gas analyzer manufactured by H. 

Maihak, A. G. J in Germany. The UNOR has been used at the Barro~y station 

since the start of the program in July 1973; the remaining obse rvatories 

have the URAS analyzer made in Germany by Hartmann and Braun, A. G. 

16 
During the year, an exchange of a naly z e r s was required at Barrow 

because o f a f a iling UNOR. An URAS ha s be e n purchased for Barrow and is 

scheduled f or ins tallation in 197 7. All the URAS instruments opera ting 

at the other s t a ti ons ra n througho ut the year with out major difficul -

ties. Table 4 list s the provi s ional monthly mean carbo n dioxide concentrations determined at fou r GMCC s tations for portion s o f 1976. Figure 

4 i s a graphic pres ent at ion of these data. Mauna Loa data are available 

for the entire year. Barrow data for January, February , March , and 

April are questionable, becau se the analyzer air intake sys tem had a 

leak. 

Tab l e 4 . Prov isional ~\onthl y Mean CO2 Concentrations 

=- . ' ..... -=- ---

19 76 Sout h Pole Samoa Mauna Loa Barrow 

Ja n 322. 04 ppm 324.12 ppm 324. 78 ppm (329.97) ppm 

Feb 321. 82 324.28 325. 56 (331 72) 

11a r 321. 67 323.89 326. 15 (333.12) 

Apr 321. 67 327.00 (33617) 

May 321. 70 327.18 330. 63 

Jun 321 .86 326.83 329. 24* 

Jul 325.62 

Aug 323.99 

Sep 322. 84 

Oct 322.67 

Nov 323. 79 

Oec 325.13 

*First 16 day s only. 

Note: Data 'in parentheses were affected by l eak in a i r intake line. 

The frequency at which reference gases are us ed t o calibrate the 

co ntinu ous analyzer was chang ed late i n the year to economize in use of 

reference gases. Previously, the t wo working referen ce gases h ad been 

run for 5 minute s on the hou r and the half hour. At pre sent, they are 

run once an h our on the half ho u r f or 5 mi nutes. The change was initiated only after a study proved tha t no adverse effect on the data qual -

ity would resul t. 

17 
N 

o 

u 

" M o 

Figure 4. Provisi onal mon thl y mean 

C02 concentrati ons J 19 76 . 

The carb o n d i oxide flask sampling program wa s enlarged during 1976. 

Flask s ampling is perf ormed at all the GHCC observatories by llsi ng an 

apparatus built int o the rack of the continuous analyzer. By acti vati o n 

of a solenoid valve} air that normally passes through the air i ntake 

line into the analyzer is diverted i nto the paired glass flasks for 

simultaneous flushing and fill i ng to an overpre ss ure of 1 or 2 p.s.i. 

HLO, the last of the stations to i mplement this technique, commenced 

samp ling in July. All flask sampling is done weekly, except at the 

South Pole where samples are taken only on the first and fifteenth of 

e ach month. Three additional flask sampling programs were started 

during the year: the program at Niwot Ridge. Co lorado, was restarted 

after being i nactive for 23 months; the Key Biscayne, Florida, program 

was also resumed after a 20-month break; and a program was initiated at 

Cape Kumukahi to provide sea level samples on the island of Hawaii. Tbe 

1976 provisional data for the seven flask sampling programs are given in 

Tables 5 and 6 for hand-a sp irated samples and through-the-analyzer 

samples. Figures 5 and 6 graph these data for the Southern and Northern 

Hemispheres. 

4.1.2 Total Ozone 

Observations of total ozone are currently made with Dobson ozone 

spectropho tometers at the 12 stations listed in Table 7. During 1976 , 

a number of poss ible field sites were surveyed for a West Coast Dobson 

spectrophotometer observatory. The list of candidate sites ha s been 

narrowed to three s tations; Fresno, Bishop, and White Mountain Peak, 

all in California. F i nal s ite selection and implementation of station 

facilities are expected in 1977 . 

Calibrations 

Recalibrations of three Dobson instruments (No. 63 at Mauna Loa, 

Hawai i; No. 72 at Wallops Island , Virginia; and No. 3 3 at Bismarc k, 

18 
Tab le 5. Provisional Mean Monthl y CO2 Index Values Determined From F'1ask Sampl ing 

Taken by Aspirator Bulb in 1976 

Cape Kumukahi Ket Bi a~n e Ni\llot Ridge 

Mean Mean Mean 

# of Conc. # of Cone. # of Conc. 

Month Samples Index 0 Sample s Index (J Samples Index (J 

Jan 4 326.84 0. 55 

Feb 4 327. 76 0.59 

Mar 4 327.69 0. 56 4 328. 14 0.48 4 328.73 0. 58 

Apr 4 329.04 0.52 2 328. 74 0.25 5 329.71 1. 93 ~ 

'" May 4 329.69 0. 67 4 329.23 0.61 3 327.88 0. 66 

Jun 4 327.96 0. 96 3 327.84 0.35 5 326.84 1. 45 

Jul 4 325.53 I. 06 5 327 . 00 1.45 4 323.92 2.43 

Aug 4 32380 0.85 2 324.97 0.48 4 323.68 0.88 

Sep 5 323.84 0.74 3 324. 19 0.31 5 323.41 1. 57 

Oct 4 323 . 98 1. 01 2 324 . 60 1. 37 4 324. 72 0.46 

No v 4 326.80 0.93 2 325.89 0.29 4 326. 03 0. 62 

Dec 4 326.25 0.47 2 326. 15 1. 24 4 327.24 0. 76 
Tab le 6. Provis iona l Mean Mon thly CO2 Index Val ue s Determined From 

Through- the - Ana lyzer Flask Sampling i n 1976 

South Pole Samoa Mauna loa B-a rr o.w 

Mean Mean Mean Mean 

h of Cone. h of Co ne . h of Cone . H of Co ne. 

Month Samples Index 0 Samp 1 es Index 0 Samples Ind ex 0 Sampl es Index " 

Jan 2 324.14 0.09 4 (33128 ) 1. 70 

Feb 2 (33 7.42) 1. 28 

Mar 2 324.23 0.3 1 2 325 . 60 0.85 5 (338.68) 3. 36 

Apr 2 323 . 93 0.07 5 325.64 0.97 3 (341.19) 5.81 

N 

0 May 2 324 . 21 0. 04 4 325 .73 109 3 330. 85 0.58 

J un 2 324.30 0. 12 4 325.72 0.35 3 324.59 0. 50 

Jul 2 32 4. 54 0.18 5 325. 29 1. 45 2 326.26 0.16 , 325.10 1. 86 

Au g 2 324.95 0. 16 2 325. 70 0.18 4 325 . 20 0. 50 2 318 . 80 1. 64 

Sep 2 325.29 0.10 5 325 . 98 0.45 5 324.34 0. 32 4 322.79 2. 37 

Oc t 2 325.62 0. 14 5 326.50 0. 77 4 323.64 L 06 5 32J. 14 1.92 

Nov 2 325.70 0. 22 3 326.59 0.33 5 325. 18 0.50 2 327.76 1. 30 

Oec 2 325.53 0.09 1 326.74 4 326. 13 0.60 5 329.22 0. 58 

Note: Data i n parenthes e s wer e affected by leak in air i ntake l i ne. 
32 r---------~,---;-- J 

> 

} 320f--

Figure 5. Flask sampl i n g data for 

the Southern Hemisph ere , 1976 . 

J J A S O N 

Figure 6. Flask sampl ing data for 

the Northern Hemisphere , 1 976 . 

North Dakota) were condu cte d during the sununer of 1976. In addition) 

e xt e nsive o b s ervations were mad e at Ma un a Loa f rom June to August 1976 

wi th Dobson s p ec trophotometer No. 83. This wa s done t o ca librate the 

NOAA s t a nda r d o n an absolute scal e . During 1976, the International 

Ozone Commi ssion re commended to the World Meteorol ogica l Organization 

(WMO) tha t U.S. Dobson i n s trument No. 83 b e establish e d as a World 

Primary Standard instrwne nt for total ozone me a s ure me nts. 

Observati ons we r e a l so made at Bismarck a lld Ma un a Loa obse rvatories 

(with instruments No. 33 a nd No. 63, respectivel y) duri ng the summer of 

1976 in a program de sign.ed t o i mprove the q ualit y of zenith sky type 

observations. Analysis of the data ha s n.ot ye t been compl eted. 

Tab le 7. The U.S. Dob son Spectrophotome t er Network 

Station 

Bismarck , N. Oak. 

CaT' ibou , ~la i ne Tutu i la Is land, Samoa 

Ta l laha sse e, Fla. 

Maun a Loa , Hawaii 

Wa 11 ops Isla nd , Va. 

Barrow, Al aska 

Nas hvi I Ie, Te nn. 

Amun dse n- Sco tt, South 

Po l e 

Boulder, Colo. 

White Sands, N. Nex. 

Huanc ayo, Peru 

In st rument 

Se r ia I 

Period of Record No. 

010163 - Presenl 33 

010163-Presenl 34 

121975 -Pres enl 42 

060273- Prese nl 58 

0lO264 -Pre sent 63 

070167- Pre sent 72 

080273 -Pres ent 76 

OI01f>3-Present 79 

I 20 563-Present 80 

09016 6-Present 82 

010572-Present 86 

021464 - Pre se nt 87 

21 

Ag ency 

NOAA 

NOAA 

NOAA 

NOAA/F lo rida 

St a te U"i 'Jersity 

NOAA 

NOAA 

NOAA 

NOAA 

NOAA 

NOAA 

NOAA/Department 

o f Army 

NOAA/H uancayo 

Observ ato ry 

D 
Data 

Dai ly 19 76 total ozone data (appl icable to lo ca l apparent noon) for 

all s t ation s exc ept Amun dsen-Sco tt are availa ble now i n Ozone Data for --- --- -- the World. tl ea n monthly total ozone values for the NOAA o bservatori es 

and coop e r a tive s ta lio n s are pres e nted i n Table 8. 

Table 8. Provi siona l Mea n Monthly Tola l Ozone Amo un ts ( mil l i-atmo-cm), 1976 

~ 

Jan Feb 11ar ApI' May Jun Ju l Aug 5ep Oct Nov Dec 

Bismar ck, N. Oak. 352 371 389 364 357 337 31 4 308 294 301 334 334 

Caribou , Maine 406 408 382 362 393 348 34 9 321 321 317 349 357 

Tutuila Is., Samoa 263 262 261 255 264 266 262 268 267 276 273 264 

Tallaha ssee , FI a. 313 299 298 328 336 334 327 319 308 294 29 3 294 

Mauna l oa 1 Hawa i i 269 270 294 289 298 287 276 278 267 264 264 255 

\.Ja l1 ops Isla nd, Va. 333 312 331 345 353 338 333 324 311 309 314 313 

Barrow, Alas ka 463 44 3 422 355 332 292 319 308 

Na s hv i l I e, Tenn . 33 4 323 337 330 350 348 334 320 312 311 318 314 

Boulder , Co lo . 314 33 3 368 353 348 327 307 306 302 304 295 299 

White Sands, N. Hex 315 296 330 329 341 309 312 312 290 295 297 295 

Hu anc ayo , Peru 273 27 9 275 269 270 274 272 278 283 280 278 271 

4.1.3 Surface Ozone 

There is n ow a complete year of data fr om Samoa, so ma ny ba sic 

featu res of su rfa ce ozone distributio n at a ll GMCC ba se line s tati o n s can 

be described. Ther e h as been rene wed interest in troposp heri c ozone, 

and there are claims that tropospheric pho to c h e mical proc esses playa 

large role in determi ning the ozone distributio n of the troposphere 

(Cr utze n J 1974). GMCC c lean air nleasu rements ca n s he d some light on the 

p rocess es involved . 

Program Changes 

To standardize surfa ce ozone measu rements , all obs ervatories ha ve 

been equ ipped with ne arly id entical sets of mo nitoring equipment. Eac h 

ob se rvatory has an ECC Mode l No. 005 ox idant meter (see Swnmary Report 

NO . 1 for a description of the ECC meter) , a Dasib i ozone photometer 

(see Summary Report No. 4 ) , and a modified Mcr-lil lan ozone ge nerator (see 

Summary Report No .4) fo r calibra tion. In addition, the ECC and Da si bi 

i nstruments ha ve been run almost con ti nuo u s ly at the Fritz Peak Ob servatory in Col orado) a nd an ECe meter is o perated at Bo ulder. 

An improved ca lib ra ti o n proce dure wh ich a llows f or better utiliza ti o n of the ICDAS ~Yas impleme n ted . Th is proced ure e n s ur es that 

ca libration i n f ormation is properl y recorded for easier access when the 

data are processe d. A reversed ca lib ration schedule cal l s fo r once -aweek cal ib ration checks of both the ECC a nd Dasibi o zone mete r s . 

22 
Data Summary 

The basic features of the surface ozone distribution at Barrow, 

Mauna Loa, and South Pole were described in Summary Report No.3. Two 

features o f the surface ozone distribution at Samoa stand out. As at 

the other GMCC observatories , surface ozone at Samoa shows a strong 

annual variation with a maximum in August and a minimum in April. As 

can be seen in Figure 7 this variation is in phase with that at South 

Pole, but out of phase with the 3Iillual variation at Mauna Loa. In the 

Southern Hemisphere tropics the total ozone maximum occurs later (about 

October) than the surface ozone. This suggests weak coupling between 

stratospheric and near-surface ozone at these latitudes. 

Another prominent characteristic of the surface ozone behavior at 

Samoa is the generally lower absolute amount of surface ozone. This is 

brought out in Figure 8 where the surface ozone mixing ratio is plotted 

as a function of latitude for the GMCC stations and Fritz Peak. The 

large summertime va lues at Fritz Peak probably are partly due to local 

photochemical production. This limited latitudinal profile suggests a 

midlatitude maximum in the Northern Hemisphere. 

Banow (71 flNI 

3 0 ~ 1 f ! -

0 

frill Peak 1<10o '·n -

! ~ 

o =i ? 3 

. 0 

& 

" " I\>\a .ltl'; l O<t 120 0 N) 

-

! ! f ~ 30 ~ 

~ 

~ 10 o 

(; 

20 

10 

30 

10 

! 

1 S¥flO) (II,OS I 

t! • ~ • ,l,. SQlt!" Po (I lOGOS] 

! ~ ~ ; 

t--

! 

! 

! 

! 

~ 

F ("I A M 

I 

! ? 1973-76 

f t 

1975·76 

! ~ 

1973-76 

! ! 

1976 

~ ~ 

1962·66 

f til: ! 

! 

0 ECC liO 

} '0 

! ~ ! ! 20 

--- 0 

ECC 

40 

f ! ! ! ! ' 0 

" 

r 

ECC 

f 20 ! • t 

F!IJY C.hl!l"JlI iU _ 0 

§ • ~ ! ·)0 

y20 

0 A SO N 0 

23 

Figure 7. Me an monthly surface 

ozone. Standa rd d eviations repre -

sent variability within the month. 
At Samoa there is a greater diurnal variation in surface ozone 

during the austral winter and spring seasons tha n in the other two 

sea so ns. This is shown in Figure 9. Whether or not suc h a variation is 

a real feature of the surface ozone d istribution is questionable. It 

may be an artifact of the sampling locati on above the main observatory 

building s ince some diurnal variation in the air ventilation at this 

site has been noticed. By the middle of 1977, a ne w sampling location 

with a much better exposure will be in operation. This should answer 

the question of the reality of the diurnal variation. 

During 1976, the ECC and Dasibi ozone meters were ope rated simultaneously at the GMCC stations and at Fritz Peak. The monthly mean 

values for the peri od of compari son from each instrument are shown in 

Figure 10. The Dasibi values for each station have been adju sted by a 

constant factor to bring them into agreement with the standard ECC scale 

represented by ECC Meter No. 001-1. In general, the month-to-month 

variations are reproduced well. On a s horter time scale, the agreement 

is also good between the two different types of instruments. On an 

ab so lute sca le, the Da sibi ozone meter doe s not give good agreement with 

the ECC meter. All the ECC meters give comparable results on an ab solute scale, but the Dasibi meters do not. It is for this reason that 

the Dasib i values are adjusted to a common scale based on the ECC meter. 

\ 

\ 

4,')US \ 

\ 

(iQOS \ 

\ 

Coos ,-- II r 

10 3u 

, 

, 

, 

, 

\ 

, 

, 

, 

\ 

, 

, , , ' \ \ \ , \ , 

"ill'" , ' , ' t 1\ I \ . 

50 10 30 50 lO ,JO ':1 0 oQ 31) 50 10 30 :'U 

0: ,.,.' \"J "",- \ ' 'r"'" fl .. l ln II' P~ "' '' c [ld '" 11 

Figure 8 . Surface ozone plotted by 

latitude--seasonal and annual 

averages. 

24 

Samoa (12"S1 ECC 

Figure 9 . Diurnal surface ozone a t 

Samoa --seasonal and a nnual a verages . 
Barrow (71 0N ) 

ECC 

ECC 

10 -

~ 10 

• 30 

o " 

10 

30 

10 

30 

10 

ECC 

ECC 

:L :-----lcc'-----LlLLLJUJ_D,_,iI.L,; .LJ 

J A S ~ '. ') J ... A ·1 J J A S O l\! 0 J F 1\>1 ~ .' ... J J 

1975 1976 1977 

Calibrations 

Figure 10. Monthly surface ozone 

measured by ECC and Dasibi ozone 

meters. 

During 1976 an ECC meter was compared with the ozone standard 

instrument maintained by the National Bureau of Standards (NBS). 

Preliminary results indicate that the ECC meter reads higher than the 

25 
NBS sta nd ard by about 5% over a wi de range of ozone values, and hi gher 

by about 2% over the raIlge f r om a n ozone partial pressure of about 2 0 to 

70 nanobars, which in cludes almost a ll the data from t he GHCC observatories. 

4.1.4 Halocacbons 

The weekly exposure of an eva cuated stainl e ss steel cylinder has 

co n ti nu ed at Barrow, Mauna Loa, and Samoa throughout 1976. In addi tion, 

a se t of special flask samples was take n at the se stations du ring late 

October a nd early November in cooperation with the NASA Latitude Survey . 

A dual evacuated cyli nde r program was instituted at Niwot Ridge, 

Colorado, in Janua ry and continued through the year. I NSTAAR , which has 

facilities on Niwot Ridge, was under contract to expose the pair of 

fla sks ea ch week. 

A dual cylinde r pump-up system was tested during January at the 

South Pole s tation. 

Instrumentation 

A numbec o f changes and addition s helped improve the quality of the 

da ta. During Hacch 1976 , the Hewl e tt-Packard chromatogcaph wa s electronically modified acco r ding t o the manufacturer's re commendations. 

This permitted the va r iable frequency mode of operation t o be used with 

ult r apure nitroge n carrier gas. The change brought about a sensitivity 

increase of 2.5 . The Idaho Falls detector and fixed-pulse electronics 

were no longer u s ed. A ma ss flow control ler was in s t alled in the 

carrier gas line in April to reduce flow flu c tuations a nd their effect 

o n dete ctor r esponse. Negati v e chromatogram p eak s were observed and 

found to be caused by halocarbons in the carrier gas despite the ultr a -

pu re (99.999%) nitrogen used. In August, a Supelco Gas Purifier was 

installed in the carrier gas line wh ich reduced halocarbon imp urities t o 

an amount below their dete ctable limit. 

The cy linder pump-up tests run in January at South Pole showed 

unfavorable resu lts. Followi ng a c riti ca l review of the fla s ks and pump 

system, chaIlges ar e being made to improve the sampling system. Our 

stainless stee l cylinders are being passivated by the SUMMA electropolishing process deve l oped by Molectrics, Inc., of Englewood, California. 

It is believed th is wi ll minimize cylinder wall effects that cause 

modification, adsorption or desorpti on of co llected trace halogens. The 

cylinde cs are being equipped on both ends with a ll stainless steel Nupro 

type SS- 4H b e llows valves. These valves contain no elastomers or 

polymers that could serve as h alocarbon so urces or sinks. After chemi ca l cleaning, the cylinders ar e evacua ted while heating, then f illed 

wit h zero air. Chromatog r ap hi c purity checks are mad e a day and at 

least a month later by sampling the zero air. 

26 
The dual cylinder pump-up system has been simplified. The pump 

system contains a 7-mi cron all stainless steel filter at the inlet to 

the stainless steel bellows pump. At the outlet of the pump, the gas 

flows through a relief valve , then through both cyl inders which are 

parallel. The inlet of the pump system is connected through a short 

sec tion of stainless steel tubing to the gas stack manifol d at each 

station. 

Future Program Developments 

The dual cy linder pump-up system described in the previous sec tion 

will be tested at the South Pole facilities during 19 77. Samples taken 

in Janua ry and February will be used to assess the quality of the system 

and the value of deploying similar systems to all of the baseline 

stations. Cylinder pairs will also be pumped up monthly through the 

rest of 1977 to test for long-term sample stabil ity. 

A major emphasis during the coming year will be developing reference gases for chromatograph calibration. Large cylinders will be pressurized with background air, and referen ce values of halocarbons will be 

determined through interlaboratory and standard gas comparisons. 

Analy sis for ot her hal ocarbons, suc h as dic hl orodifluoromethane 

(F-12) and nitrous oxide (N2 0), will be possible when reference gases 

become available. 

Data 

Our comp l ete 1976 data base for trichlorofluorometha ne (F-11 ) is 

presented in Table 9. These data are graphi cally presented wit h earlier 

data in Fi gure 11. The scatter in the data and the sta ndard deviations 

have decrea sed . This is partly due to increased control of parameters 

in the chromatographic analysis. Also, the evacuation of sampling 

flasks has been monitored more c losely. 

Of the three basel ine stati ons Barrow has the highe s t concentrations, Samoa the l owest, and Mauna Loa is in between. This is what is 

expected. However, a phase difference is also likely but is not readily 

apparent from the graphs. In fact, the concentrations appear to have 

risen and peaked together. Whether the rise and fall is a true annual 

cycle wil l need at least another year's data to determine. 

Niwot Ridge samples were taken in pairs of flasks. ~10st of these 

pairs showed coincidence. Early in the sampling, one pair consistently 

was not coincident and had F-ll concentrations higher than expected. 

That pair was considered contaminated and was withdrawn from the sampling rotation sche me in early June. 

A plot of the Niwot Ridge data indicates close agreement with the 

Hauna Loa da ta. 

27 
Table 9. 1976 Data Base fo r CC13F 

Barrow Mauna LOd Niwo t Ri dge Samo a Cone. Cone. Cone. Conc. Co ne . l{Doth 0" (POll') a 0" (ppl v) a 0" (pplv) a (pp t v) a 0" ( pph) , 

Joo 5 3.1 2 9 1878 3 1. 152 153 2 " 21B 

19 241 • 17 21. 2 23 144 146 2 25 171 2 

feb 17 274 • lJ 117 7 131 145 19 1. 7 Z5 ,.9 5 24 ' . 0 778 

Ma r lJ DO 2 11 l3b 2 7 900 m 9 2.3 1 19 lJ9 , 23 189 2 10 U7 3 168 18 .22 13 23 llO 1 30 121 1 18 IDS , 11 7 26 102 1 

24 118 2 

Ap' 2 138 2 1. 250 2 122 1 122 1 2 118 2 19 120 2 24 38000 8 131 2 129 1 7 25. 5 28 1.1 2 15 115 2 123 2 is 131 , )0 150 1 138 1 24 123 2 

H.y G &30 " 5 11l 2 5 11 9 J III 3 9 459 6 12 1'3') 1 14 llJ 2 14 118 1 I1B 2 15 101 2 21 127 2 26 10' 2 Z4 119 3 121 19 lOB 1 25 115 1 

J O" 14 3 • 3 122 5 2 Ig4 1 174 1 • 122 ) 

13S 1 10 l2l ) 8 120 1 120 1 10 106 1 !? 12' 1 17 113 3 1. IlS 3 117 1 19 113 3 24 118 2 123 1 24 112 3 30 1434 19 1672 lJ 

3 143 2 1 124 7 13l 1 130 2 3 ill 1 7 3.5 9 125 22 lZS , 125 1 8 11) 1 13 139 2 22 l2b 30 122 2 123 1 15 117 2 21 !~ l 29 126 2 22 11. 2 27 l87 29 119 3 

40, 12 127 2 11 9 1 , 1il 2 120 , 5 117 1 25 15) 1 12 120 1 12 119 3 119 1 12 124 1 18 302 5 20 121 1 132 1 19 121 2 25 571 , 2. 133 2 132 1 2. m 3 JO 143 2 

Sep 7 1.5 , :C " 3 1 5 ". 2 14 5 1 2 129 15 '" 3 :S 14 9 1 10 15 1 1 151 2 8 132 

" 159 2 2i 145 2 " 142 142 2 23 lJ5 

29 173 1 28 155 2 30 131 

Oc< 5 215 1 • is' 1 5 152 1 153 1 7 144 

IS 188 1 12 1.2 1 14 175 2 174 1 13 153 19 105 2 20 1i9 2 23 18. 1 18' 2 2i 155 27 '" 3 29 l5J 2 28 186 1 185 1 27 172 

29 '0. 2 

104 2 

205 2 

,'lO ll 2 '02 1 192 2 • 178 177 4 175 2 1. m 5 188 2 12 185 8 165 1 10 207 1 19 173 2 171 174 J 1. 172 1 " 174 2 175 165 1 22 177 2 11 156 1 29 177 1 18 1.2 1 

25 J7b 3 

0" 3 ('(1!) 2 , 172 2 3 183 182 5 1 158 l 

8 196 , IS 117 ) 9 169 168 1 1. 160 2 

" 2" ;:: 2 22 110 2 22 l7l 171 1 ). 154 1 10 m 1 29 17G 2 29 171 112 1 

28 193 2 

28 
500----,-

2- <laO' 

2 300 

~ 

o lOOl .' " •• 

:j 100 1 ",.,."_ .... ., / . 

,. ::. 

MO rl. --- - -, i'J \', O i RiLJgf. 

~ ... 00 1 

~ 300 -

2' : ~ 

9 '9, 1 .... '-""'"" 3 ICIO 

o'====~ 

' .. .. 

," I .. ~ ..... 

500

o 

- ----

--

---- --· --- - --

--- - - -~ -----, 

~ JOO 

~ 200· 

:. . '. :," : 10D- ' " .... l,.· . U r.', 

. ' 

',hun .. l oa 

.t: 

,' , \0"-

J.:. .i -

50g-' ---------- .. -- .- -.~ 

~ JOO 

~ 300 

~ 200 - .. u iOO ',' ', ...... . .... 

0 - -,--- - 19i3 197.l 

'0."'" . ' " • " " .... l . .. .... 

19 7~ 

' . .... . 

\971j 

" " 

Figure 11. CC1 3F c on centrations at 

four GMCC observatori e s . 

4 .2 St r ato sphe r ic Ae r osol Me asur eme nts Using Lidar 

Since t h e la st report, nlonito ring of stra t osphe r ic aerosols over 

Ma una Loa ha s rema i n e d the major a ctivity. Data we r e taken at Maun a Loa 

20 times d uring 1976 . In general, the t re nd during this period wa s a 

r e turn t o a c lean s t r ato s phere after the volcani c i nj e c t ion by the de 

Fue g o volca no in Gu a t ema l a du r ing October 197 4 (Fegley a n d Ellis , 1975 

a,b; Rus s e ll a nd Hak e , 1977). Howeve r , on Janua ry 24, 1977 , a n ew, 

inte ns e v olc anic-l i ke cloud wa s d e t ec t ed at t h e tro p opa us e a b ov e Maun a 

Loa. To o ur knowledge , as of t he date of th is writing (3/77) the c l o ud 

ha s no t b ee n de t e cted a t o ther lo c a t i o n s . I t seems to h ave d e n s ity 

c omp a r able with that o f the de Fuego cloud, but it i s mo r e patch y, 

d isap pea ring and re app e aring every fe w d a ys. 

29 
Hardware Development 

During the fall, a NOVA mini comp ut er system was insta lled in the 

lidar dome. This change was made b eca us e it wa s previously nece s sary to 

interrupt the ICDAS during lidar operation. Th e lidar program no w 

remain s in the c omputer at all times, so lidar operation is quicker and 

s i mpler. Mino r modifications of the lida r analysis program were mad e, 

re sulti ng i n more complet e documentation, greater ma thema tical acc uracy, and greater eas e of use. 

Additionally, a diagnostic rout i ne was incorporated to t est the 

Bi omat i on di g i tizer unit at op e rator request . This particular un i t ha s 

been the l e ast rel ia ble link in the t o tal system . It is sub jec t to 

electronic drift a nd require s real ignment at least yearly. It is als o 

affected by room temperature fl uctuat i o n s. It is h oped tha t lidar room 

improvements planned for 1977 wi ll r e gulate the temperatur e and red u ce 

probl e ms with this un i t. 

The next s tep in the MLO li dar development will be inco rp o rating 

the CAMAC interface s ystem and then partially automat i ng the lida r 

s yst em. More shots will the n be possible with greater s tatis tic al 

a c cura c y at higher altitude s (25- 35 km reg i on) . Photon co un ting will 

als o b e u sed a t the longe r ranges t o provi de greater accuracy. 

Du ring 1976, the remaining hardware for the Ba rrow lidar wa s proc ured. A n e w dye laser with a pulse energy o f l~ joul es (J) was purchased. Thi s unit wi ll be opera te d in th e r egion of 6300 A* wh e re n e w, 

hi gh efficiency red dyes are availabl e . This region is optimal fo r 

aeros o l det e cti o n and s imultaneous hi gh effic ienc y pho tomultiplier 

detection. Following are the opera tional par ameters of this s yst em: 

Puls e e nergy - l~ joules 

Wavelength - 6300 A 

Receiver aperture - 40 cm diame t er 

Fre s ne l lens 

Maximum r epetition rate - 10 shots/minu te 

De tector - RCA 7265 

Pulse length - 0.5 micro se co nd s 

Signal process or - Bioma tion mo del 805 digitize r, 

Camac int e rface , NOVA min i computer. 

Th e Barrow s ystem wi ll be de si gned to ope ra te through a window in 

the roof of a sma ll building. Thi s is i n contrast to MLO wher e the 

system i s located in an a s tronomical dome without a wi ndow. The dy e 

laser is also capable o f being oper a ted at different wavelengt h s. 

*A i s used fo r Ang s t rom thro ughout th is repo rt. 

30 
Operating Difficulties 

Three months of data (October-December 1976) were lo s t because of 

an unrecognized problem with the Biomation digitizer. The unit was returned to the fa c tory for alignment in Dec ember . A Biomation diagno s tic 

routine , which places portions of the output onto the teletype for 

operator examination a nd archiving a t Boulder, wa s incorporated into the 

lida r program. Now, an experienced op e rator c an spot de f e ctive operation. ~1en the lidar i s a utomated, it will be po s sible to build in this 

diagnostic routine s o that the computer c an continuously c h e ck the 

Biomation. The Biomation Co. ha s p rovided instructi ons on how to a l ign 

the unit. 

The fla s hlamp failed two days a fter the new dust c loud was detected. Upon replacement, an explosion blew up the lamp-rod cavity. 

The unit was s ent to the f a c tory for rejuvenation. The high voltage 

system would not c ha rge when the unit wa s returned. After uns uc c e ssful 

attempts to r e p a ir the circuitry, this unit wa s als o returned to t he 

factory where new d i odes were i n stall ed. We have never been able to us e 

a flashlamp longer than 1 year. This amounts to only about 1000 shots, 

which is much le s s than the manufactnrer claims. We have always had t o 

r un highe r voltage s on the lamp than the manufa c turer recommends, and 

this may explain our difficulties . Our Pocke l s cell appears optically 

distort e d, and p erhap s this nec essitates our highe r voltages. 

Data were not co llected during August and September becaus e the 

station minicomputer was not functioning. The computer system for t h e 

lidar being developed for Barrow also ha s had several difficulties. The 

memory failed soon after delivery, the teletype had probl ems, a nd the 

NOVA s o ftware had some errors i n it. This ha s slowed program deve lopment for both MLO and Barrow. 

Data 

The s t ra tospheric data are summarized in Figure 12. The enhanced 

backscatter layer generally extended from 17 to about 23 km msl. The 

maximum backscatter coefficient average declined somewhat t hrougho ut the 

period January 8, 1976, to January 19, 197 7 . As st a t ed before, on 

J a nuary 24, 1977, a new layer wa s s ighte d visually; on January 26 1 the 

lidar was used to establish the height at 16.2 km ms l, slightly below 

the tropopause, as det e rmined by Hil o upper air data, The max i mum 

backscatter coefficient i s approximately 50 times greater than that of 

the previous wee k. In fac t , i t i s comparable with that of the de Fuego 

dust cloud. 

The enhanced back sca tter layer is not continuous horizontally. As 

seen in Figure 12 , on Januar y 26 it covers the s ky , but on J anuary 27 

the cloud s eems t o be gone, although the dust conc e ntration at higher 

altitude s appears to be enhanced . Additional analys i s of the da t a will 

be de s cribed in for t h coming publications. 

31 
::; 

~ 

~ 

S 

0 

~ 

~ 

;;' 

~ 01,,29 

10 

30 

Jun 3 

20 

10 

30 

20 

I~ J,n ~ 1977 ~ 26 

.~ "> ~ ,50 

10 j ~ I 

20 20 

J llr\ ~ 

l I 

<~ n 27 

I 

20 

- Figure 12. Non-Rayl e igh b ackscatter 

c oe f fi c ient (10- 9 m- 1 Steradians- 1; 

in Mauna Loa . 

It i s i mportant to emphasize that the data displayed are not raw 

data. Some a s swnpt i ons have bee n made in analyzing the r es ults. For 

instance, we a ss wne that a c lea n layer (i. e. any Raleigh sca ttering) of 

the atmosphere exists i n the region 15-16 km msl. This produce s the 

r elative mi nimwn shown o n the graphs. Our asswnption has been experi -

mentally te s ted on several oc ca s ions by other workers and generally 

s eems to be borne out (See Rosen, Ho fmann , and La by , 1975). A s e cond 

assumption i s that there is no aero s ol a t the longest range, in this 

case about 3S km msl . Th is also ha s been te s ted experimentally by 

others a nd ha s b ee n f ound to be generally true. Bu t there were several 

occasions when others found significant a e r osol at 35 kID, and \v e could 

not de tec t th i s in o ur a nalys i s. It is unfortuna te but necessa ry that 

we make t his a ss umpt ion . 

Th e data displayed are typi ca l o f ou r stratospheric r es ults. Also, 

some returns from t he middle troposphere have not been shown . During 

October to De cember 1976, some u se ful tropospheric returns we re available, even though the Bi omation di f fi c ulties prevented r e trievi ng 

use f ul stratospheric r es ults. 

32 
4. 3 Surface Aerosol Me a s u reme n t s 

The GMCC s u r fac e a e r o s o l program f o r 19 76 incl uded the me a s urement 

of condensation ( o r Aitken) nuc le i a t all site s , and integrated light 

scattering (by a 4-wa velength nephe l ome t e r) at Mauna Loa . A second 

f o ur-wa v e l e n gth ne phelomet e r was o p era t e d at Ba rrow during May and June 

1976, In s t r uments in the f i eld during 1976 are summariz e d in Table 10. 

Table 10 , Instruments for Sudace Aerosol Measureme nts 

at Field Sta tions 

"'launa Loa Barrow Samoa South Pole 

St andard Gardner X X X 

Long-tube Gardn er X X X X 

G. E. counter X X X 

Pollak count e r X X X 

4-A nephe lomet er X X 

Aitken Nu c l e i 

Maintaining a stable calibration base i s fundamental to successful 

l ong-term Aitken nu c l eus monito ring. The r outine Aitken nu c l e u s mo nitoring instrument a t each s ite is a G.E. c ondensati o n nu c l e us counter 

wi th modifica tions incorporated a t the Unive r s ity o f Was hingt on . 

Briefly, the modifi e d G.E. co unter us es electronic tec hniques that give 

g r ea tly improve d stability a nd incre a s e d sensitivity. The prove n cloud 

chamber, usi ng a low forward-scattering angl e detection s c he me, a nd the 

rotary valve providing fiv e meas u rement cyc l es per seco nd remain the 

s ame . Howe v e r, the improved electronic processing gi v es a lower limit 

o f s e n s itivi ty below 10 nuc lei cm- 3 , This sensitivity is necessary at 

So uth Pole, ou r c l ea n est site. Figure 13 is a simpl i fied blo c k diagram 

of G.E. counter ele c tron ics , Figure 14 s hows the air flow a nd valve 

sch eme , and Figure 15 gives the geometry of the e xpansion chamb e r, 

A long-tube Gardner coun ter is located at e a c h site a s a backup 

monito ring instrument and i s e s pecially u s eful at r emote si te s because 

o f its portabili ty. The l o ng-tub e Gardner c o unter has a fog tub e twi c e 

a s long as the standard Gardner coun ter . The f o g tube p rovi d es about 

twic e the sensitivity, and meas ur eme nt capabi lity t o below 100 nuclei cm 3 

The l o ng -tube Gardner is us e d to provide r6utine ca libration c hec ks o n 

the G.E. counter. 

33 
Fi g ur e 1 3. 

Fi g ure 1 4. 

log eN 

0-5 Vdc 

5 Decodes 

El ectro nic s c heme o f the modifi e d c .e. c onde nsatio n 

nucl eu s c o unter . 

/' 

/' 

/' 

l amp 

/' 

. /' 

;;; Ub~ 

PH!ssuU! 

RigIJ lalOf 

ac ll u"~ 

---- Pump 

Di a gr am of a i r f l at.; in the G .E. condensati on nuc l eus 

counter . 

3 4 
light B;;.rn £l( An<l iylical Be(lnJ 

1 ubc Beam 

l amp 

Ph:.:o Tube 

Cond£:'l!'Il(,: lens 

Neutral F.her 

V IE;wmg Volumi!' 

~ ROlilry Value ShaFt 

'----------------- ----- ------------ --- ----' 

Figure 15. Expansion chamb e r and opti cs f or the G.E. condensation 

nucleus counter. 

A Pol l ak condeIlsa ti on nucleus c o unter i s located a t e ach s it e as a 

second ary s tandard to provi de a cc urate ca libration points fo r the G.E. 

c ounter, and t o p rovid e an o n-s ite comp a rison t o e stablis h the ca libration o f a long-tube Gardne r c ounter . The Poll a k co unt e r has proved a 

very stable instrument over the lo ng term and is probab ly t he best 

choice as an on-site sta nda rd . 

Ab solut e c al i bra tion f or the Aitke n nucl e u s program will be p ro -

vided by a photog~aphic Ai tke n nu c leu s c ouIlt e r t o be ac qui red in 1977 . 

This ins trument will be trans ported to the fie ld sites for c omparison 

wi th the a ll-site sta nd ards . In ad di tion, a monodis pers e aeros o l generator, provid i Ilg a controlled aero s ol sour ce , will be l oca ted in the 

Boulder Labora t ories to proviCl. e a c ali bration of a ll i nstrument s se nt 

into the fi e ld. 

Ligh t Scatte ri ng 

Cal ib ra tion of the four-wave leIl g th nephelome ters re quires only o ne 

po i nt to estab l i sh the scale . This calibration point i s provided by 

fi ll i ng the instrument with Freo n-I2, mea suring th e integrated light 

scatteri llg , a nd se t ti ng the scale of t he nephelome ter to the known 

sc att eri ng coeff ic ie nts of Freon-12. In additi on , t he calibra ti on 

d epends on the linearity of the instrume nt ele ct r onic s whi ch can be 

checke d by in s erti ng s imulated scatteri ng s ignals i n pla c e o f the 

photomul t ipl i e r s ignals. 

35 
Th e o per a ti on o f the Mauna Loa n eph e lomet e r has be e n d esc ribe d in 

the GHCC s ummary report for 197 4 . Th e ope rati on of the Barrow nephel -

ometer and o f those to be insta lled at Sa moa and So uth Pol e h a s been 

signifi cantly impro ve d throngh a sophisticated interna l calibra tion 

sc h eme whi c h ess entially eliminates elec tronic drift a nd simplifies the 

opera tion of the instrume nts. Br ie fly, the instrument accumul ates data 

for a g iven time interval in three independen t memories whil e the 

instrume nt is fi lled wit h c lean air , with clea n air plu s a whit e c alibra t ion obj ec t, a nd wit h ambient air. Next l the instrument pe rforms the 

snbtrac tion s 

a nd 

ambient - cl ean 

ca librate - c lean 

to eliminate the effec ts of mole cular sca tter and instrument backgronnd. 

These t wo val nes are pr oportional t o the scatteri n g signal dne to a ero -

so l s alone ! a nd to the whit e ca libration object al one. The inst rument 

the n calibrates 

log ( ambi en t - cle an) - log (calibra te - clean) 

to g ive an ou tput volta ge. This voltage is propo rtio na l t o the l og -

arithm of the ratio of aerosol s catter to wh ite ca libration object 

scatter. This s tabilizes th e instrume nt a gainst drifts in lamp color 

and b rightness, fil t er tran s mission I a nd pho tomul tip lier tube sen sitivi ty. In strument ou tput is 0-10 volts spa nnin g 5 decades at 2 volts per 

decade . 

The calibratio n schedul e for the four-wave l e n g th nephel ome ter 

i n c ludes a n abso lut e cal ibrat ion using Freon-12 gas a t 2-mo nth inte r vals 

and a weekly i nternal c h e ck of t he relat ive ca libratio n obj ect . 

4 .3. 1 Mauna Loa 

Po llak co unte r SN1 3 a nd long - tube Gardne r co unter SNl185 were 

ope rated regul a rly throughout 1976. Ob s ervations were obta ined ho urly 

during t he normal working day. Fi gure 16 shows monthly geome tri c mea ns 

o f Po ll a k c ounter obse rvatio n s take n a t 1000, 1100, 12 00, 1300 , and 1400 

hr lo cal standard time (LST) . The 1000 hr observations (s h a de d da ta) 

s how a genera l t e nd e n cy towa rd low values o f ab out 200 nuclei cm- 3 

during the wi nter J a nd higher val ues o f abou t 300 nucl ei cm - 3 during the 

s ummer. Vertic al bars give sta nda rd erro r s of the mean. Th e site 

c l ea nliness dete rio rates with the afternoon upslope wind each mon th an d 

this i s shown c learl y i n the annual means given i n Figure 17. Gardner 

co unte r SNl1 85 (lon g-tube) was cal ibrated by means of a 6-month compa rison with Pollak SN1 3 on Maun a Loa ambi e nt ae rosol . Figure 18 gives 

the r es ults of this compariso n al o n g with a least squares fit of Hoe rl's 

equa t io n. A calib ration table f or Gardner SN1185 was the n made to 

convert the Ga r dlle r sca l e r eadi ngs t o nucleu s con centrations . 

36 
M 100°1--- t· ~ 

v 

; j ' j! ~ 

,. i. , , 

i .~ , .' - , , ' , 

Z 

'''J U 

'00 " n " " n n " J .. ,l f. " , ;:"1 / ,'" j\j" '"' A~IY St;l' Un ~;o., Dc.: 

"; Dnlh 

Figure 16 . Nonthly geometric mean s 

of condensa tion nuclei (MLO, 19 76) 

for 1000, 1100, 1200, 1300, and 

1400 LST . The shaded dots indi -

c ate the 1000 LST values j n i ndi -

cates the 1200 LST values; the 

vertical bars give standard errors 

about the me an (51' = (JIm) . 

'Oooor------ -,- .-,-"--.-"- '9 'l 

50[}., ;f'n'f1Is -oJ 

:& 

;; 

~ 

M 

t. 

1000 

z >- u 

I 

3, 10 '0 15 

'. ' :. :,.. j 

j 

I 

1 

: ;. i.,,' . : 

:: ...... i..~ :: . 1 

.:\~t.:~ '\:,; -

\:~::'. ' 

"';;" 1 

, 

10 5 ° Lo r .. ~ I' U;ll T·· S' 'Ie:: ~i\. ' D . or 

37 

z 

u 

• :,",~I tOllC =---:-:'-:-- 1 H.() -- ----:-:':::- 1200 --...."J....-- I JOfI -~ : tOr' 

l.J'" ':: 1. tJ!lot' f .r .p. 

Figure 1 7. Annual geome tric means 

of conden sa tion nucl ei (i1LO, 19 76). 

Vertical bars give s t a ndard errors 

about the mean ( 51' = (JIm) . 

Figure 18 . Comparison b et:toJecn longtube Gardne r counter SNl 185 a nd 

Pollak counter SN1J on ambient 

aerosol at NLO duri ng December 

1975 and JaT'Udry to i',a , 1976 . The 

curve is a least squares fi t o f 

Hoerl's equation . 
v.> 

()O 

tr:o ~' OOI 1 .L ~,,,_ ____ OO~ ~ 

Cl -' '1 ''''\''\'\'''\'\''\'\ '''\\~ ~"i l' J"" '\tyn ,\~\'''i J J "\\\'i '\''<\'\'''''' '\' '''' '''' ,\ ~~ ,~ ~~ ,: \>'~~~:'-. ~ ~,'''60 :- \\" ,\."·.11 " .,..-, " u.r., Win e! 

'Eo. .Sb~ .6 

~ 

~.·6 S ·7 -.8 ~ 1 I ._ 1 :? 3 4 5 6 7 8 9 10 r r to? IJ 1~ 15 .

8 

Jan ua ry 1976 

!; 

, 

o 

o 

g 

~' ~== [=+;/\ 1 ~~O& Willd ".f "' ''~ - .... .. . --......" ...... .., ~ '-0 J" ., .. .. . . '.?,. )" ' 0, • .1' .. .. .. .. . ~ 1 I " 10 ., ,~, . j .. . , n ~ . " " ...... . '"_~, \,\" ... , . ... _ ' .. ,.,1 , .. " . ~" j ... , ~" · •. ,. 1.Jo' .r '''- 'l.f//n- WUlc:l 

." E .6 _ -6 E 

J J CJI 7 -1 Q> 

~~..a ::: 16 11 rIJ 19 ('(I 21 22 n 4 2:' 26 :n 28 29 30 3 1 

J.) n u ary 1976 

,OO~~ ~ ~'OO. ~ ~ ~ ~ '~ ___ --l- : ___ : ~ 0 ~ 

W,na ... ,. \, , ... . ". _ .~ ~, ,, ..• - ". j ...... '" ~ .. \ ' ,", p.., 1 1 '. ~ .. ; •• T 4 . ~ .. r ,_ . f- l\ ...... . :~' '.-•• ~" . ,r.r. ,'C;\.,",- ....... . r t ;; .t . ... , '\t \'\. !.r, .... ..," ~,,~~ .. ~ .... ""',r~, .. • y l' I <I' •• ~ W" l(l 

1;J

~ 'i :

7 b ' _ _ , __ , _ _ " • f ~ -.8 1 2 

M "V 19/0 

~ 

·5 

6 

7 

\\ 1"' _ U r.( L -, " , " 

f 

o 

0, 

g 

~ ~t-7c:::7 'O ± Il:O ~ ~ '~- ...... O lr 

W "' (l ., ' ... ".rl. ... 1 •• t, /.-,'''' "o_ r/.r. , . r .-11 1" .... .. ~,,.,,. " ." .... .. _ .~ \' .. . . . _,, " ... >. u .. ' \ ~"" _ • • _' ... " ' .. .. . . ~ , \. • • v •• ,d t , ,~ .. \. ....-, J"" . ,t-., ...... '-, ~' ~ ... \. '- ~_ •• t'. W.nG (,:t ~ ·7 

Q • 

" ·8 16 " " 20 <'I ~~ - ,---. ? J :,.: :5 ?l! -.',-- Ta JO --,:-:,-,1. 8 

y 1976 

, 

o 

"' 

Fi gure 1 9 . Hourly averages of 550 nm light scatteri ng and relati ve humi dit y at MLO for Janu ar~J 

and Ma y 1976 . Wind sper d an d direc ti on are gi ve n at 3- h o ur intervals. Spr 0u is shown as thr' 

l ength of the v ector wh e re the b a rb length is equivalent t o 5 k urts (2 . 6 m s - I). 
The Mauna Loa G.E. nucleus counter operated reliably for mos t of 

the yea r, p ro ducing a c on tinuou s reco rd of nucleus co ncentrations. 

The s e data were recorded on magnetic t ape and a strip chart r ecorde r by 

the Mauna Loa data a cquisition syst em. 

The Mauna Loa four-wavelength nephelometer ope ra ted reliably 

through out 1976 with t otal downtime o f only a b out 17%. Part of this 

downtime can be attributed to recording syst em failure. Figure 19 g ive s 

hourly means o f light scattering or bsp (550 run) along with ho urly me a ns 

of re lative hum i dity of RH( %) and wind at 3-hour intervals for J a nua r y 

and May 19 76. The f irst t wo weeks o f January show some of t he lowe s t 

li ght scatteri ng data ever re corded at Mauna Loai May s hows the higher 

light scattering values typi ca l of the summe r months. It is evident 

that the very clean conditions in Janua ry are a ssoc i a ted with persistent, strong sou theaste rly wind s, an d the winds i n May are relatively 

li ght with a strong d iurnal (up s l op e-d own slope ) influence. Not e that 

wi nd s peed i s given by the length of the vector an d tha t the length of 

the barb is e quiva lent to 5 knots (2 . 6 m s -' ) . 

Figure 20 s h ows monthly means f or e a ch h our of the d ay for se l e cted 

months of 19 76 . These da t a show the same general tendencies discussed 

for s im i lar data in the G~CC Summary Report for 19 75 . 

Figure 21 shows the annual trend in light scatteri ng da ta a t Ma una 

Loa fo r 1974-76. Each point is the geometric mean of the 0100 to 0700 

LST data for all days of each month. It was f ound that the early 

morning data (just before sunrise) are probably most r epr e senta tive o f 

background tropospheri c conditions at Ma una Loa. The seasonal trend is 

evident (as discussed in t he t wo previous GHCC swrunary repo rts) with 

min i mum light scattering in the wi n ter and max imum light s ca tte ring 

during the early summer. It was also fo und that solar ra di ation turbidity data a re correl a te d with the d ata in F igu r e 21 (Bodhaine, 19 77 ). 

This s uggests that surfa ce aerosol me a sureme n ts u nder t he right meteoro logical conditions are representative of the upper tropos phere, a nd 

tha t t he tropospheric ae r oso l is partially responsible for turbidity 

va riations above Ma un a Loa. Simil a rly, the Angstrom exponent data show 

an annual variation sugge s ting that the sma lles t ae ro so ls are present in 

late autumn and e arly winter, and that the larger aerosols a re present 

during late sp ri ng . Th e annual trend in light scatte ri ng is shown mos t 

clea rly in Figure 22 which gives the 3-year means, by mont hs , of all 

0200 -0700 hr light sca ttering and Angstrom e xpo n ent data. Note the 

o rde r - of-magnitude diff erence between light scatte ring i n Hay and De cember. 

At 2330 LST on July 5 , 1975, ~auna Loa er up ted, ac tive ly f ountaining for a bout 24 hou rs. It co n ti nue d fuming for several days. Figu re 

23 s hows ho urly means of light scatte ring, co ndensation nuclei, s u rfa ce 

ozone, relative humidity, a nd wind speed and direction a t 3- h o ur intervals. Occ a sional nucl eus observations by a Pollak counter are also 

shown. These data clearly show the volcanic e ff ec ts o n the condensation 

39 
0 12 ----

'''~'rHI 0 23 - -------

Q34 

H '~-=-=:::.....:>-, >::-~~_/-~~ --.=- --" --:-- :~~-~---~;..,;-- ~-·· I M., 

6 

_ : I 

R ~----!::-------,l,---l ' I I I 

00 Oi 12 IS 7'1 00 06 12 18 24 

:i?-"

Septembe-( 

""-- "" , /~ ~~December I "-- " ~""l 6 - 6 , 

}; 

~ 

" 7 - 7 

S,~---- ~----~-- -- ~ __ ~ ____ ~ ____ ~ ____ L-__ ~ 

00 06 12 18 24 00 06 12 18 

Figure 20. Monthly geometric means for each hour of the day from the 

Naunil Loa four-wavelength nephe lome ter for sel ected months of 1976 . 

The Angstrom e xpone nt 0 12 is derived from 450 and 500 nm , u2 3 from 

500 and 700 nm, and u 34 from 700 and 850 nm. 

nu c leu s concent ratio n at MLO. During the 5 da ys before the eruptio n, 

condensation nu c leu s concentrations were about 200-300 cm- 3 with h igher 

va lues during daytime up slope wind conditions. This i s typical o f Hauna 

Loa aerosol values. For the wee k following the e rup t ion) condensation 

nu c leus values were as much a s two orders of magnitude hig her than 

usual, and e xhibited a reverse up s lope -downslo pe effe c t as well. However) light sc att e ring va l ue s are not obviously high e r than usual after 

the erupt ion) s ug ge sting that the volcanic ae r osol parti c les a re smal l 

sized and probab ly the result of combust ion or gas-to-particle conversion processe s. 

40 

24 
I'" 

( 

7 

~ 

'5 

J 

3 

-6 

- 1 

, ' I I I ! i, 

~~J F M A '.~ J ~~J A S ~~0 . DI J F ~~~~ M A 1\\ J J A S 0 ~~~ 1\ DI J F M A Pol ~~~~ J A SON ~ 0 

19 74 1975 1976 

Pigure 21 . Monthly geometric mea ns of ligh t scattering (bsp) and 

,'!ngstrom exponent for all 0500- 0700 LST da t a at IILO, 1974-76 . 

a is the average of :' l ? (450, 550 nm) and a23 (550, 700 nm) . 

5r' ~ 

't:.l .1' L ~,:,,=,,: _'-:': ~~l 

-

A,I' 'I.v JW\ J I 

" ornh 

4 1 

Fi g ure 2 2. Three - year monthly geo -

metri c means of light scattering 

(b sp) and Angstrom expone nt for all 

0300-0400 LST data at liLa, 1974 - 76 . 

a is the average of ul 2 (450, 550 

nm) and a23 (550, 700 nm) . 
... 

'" 

W;od '\,'1 "'hh\"h\ hi;- ,r J) i'. { ... p;- fo'"--.r '\ "U, '\~y' -'""VI """,-'/' (r.-_ - , rr,"",\\\"'" ... ...-"! ,,; \"1\\"'~;'\1"W\e.,\\\\\~0 W;od 

fO:~1 /\ 1 ~I ~ ±3~00~ 

D c ~~~. ~ o n 20 

a 

z 

~ 

~ E.up,;oO 

4 .• I 

J ,:~ 

2 

E 

u 

-

E 

~ D 

~ 

2 

,~,/\. 

60 

40 .g 

20 0" 

o 

5 ~ 

.. .:\ ~ 

.' Z 

..... rv:· -3 g 

2 

E 

o 

D' 

0> 

g 

Wiod "",-" l H 6 ... "'''' .... '\'\...-..-\'\'''\, ........ ...--'''''\'\J "'Ii'" •• 'JJ ). !\' " r 1.1' • ( .... .. ; "'Ii "'{, ..- "'l'\i "' rrr ... J 1 ...,i ·li\\)h )i ...... ··' .. );) .. '\ .. ,,··/ ........ ) )./ ........ , , U , 1 'il"\'\"""'I""',>;, .. ,r.r""""',\\'''4I''\'' 'li ''l~''''''' ''I ~ ~ Wind 

~'0:f?\ 1 ~I/\ : ~:OO~ 

~::b~ ~6 0 - 40 -g 

o· 20 j:O o~ a 

" 

;~ l E E u u 

Z .... Z .. '", ~ - ". 3 'v "- .. ~ 0> ... g -' 2 2 

~ .5 ~'5_ 'E 

~7 

0. ·6 -6 0. 

~ 01 ·7 01 

g~~

E 

.Bg 

-8 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 

Figure 23. Hourly means of 550 nm light scattering (b sp) , c ondensati o n nuclei, surface ozo ne, 

r elative humidity , wind speed and direction at 3-hour intervals, and occasional Pollak 

nucleus observations at MLO during July 1975. 
M 

, 

E 

0 

2 

!e 

z 

~ 

~ 

0 

<; 

~ 

0000 C----,----,----,----.-----r----,--~ 

1000 

100 

":. , 

.\' 

. ,' \ 

: . 

, .' 

log y ;. 1.923 + 0 .6639 log )( + 0.03046 }<. 

n .. 452 Oala Points 

lOO~-- 5~-- O~--~,5~--7 --~2=5-- ~3. 

Lon',] i ulle Gardner 1143 

4. 3 .2 Barrow 

Figure 24. Comparison between longtube Gardner counter SNl14 3 and 

Pollak counter SN1 6 on ambient 

aerosol at · Barrow from January to 

April and June to November 1976. 

Long-tube counter SNl143 and Pollak counter SN16 were operated 

routinely throughout 1976. The Gardner counter was operated hourly 

during the normal working day until December 14 when the lamp fa iled. 

The Pollak counter was operated hourly during the normal working day 

until May 5, at which time it was changed to a once-per-day schedul e for 

the remainder of the year. On December 15, the Pollak counter resumed 

an hourly observational schedule. During May, the Pollak couater was 

down for repair of the expansion valve. 

A comparison b etween Pollak SN16 and Gardner SNl143 for all simultaneous observations of ambient aerosol in 1976 i s shown in Figure 24 

a long with a least squares fit of Hoe rl's equati on. A calibration table 

was made for Gardner SN1143 to convert sca le readings to nucleus concentrations. It i s interesting to compare this calibration curve (Fig. 24) 

with a similar curve derived for Gardner SNl143 in the 1975 GMCC Summary 

Report (Fig. 36). Figure 25 gives the ratio of nucleus values calculated from the 1975 and 197 6 Hoerl's equations as a function of scale 

reading. The two calibration curves differ by about 25% to 10% for 

sca le rea dings from 2 to IS, the range of interest at a bac kg round site 

such as Barrow. This s ugge s ts that the calibration of Gardner SNl143 

has probably not changed significantly over the 2 years. 

43 
10,---,----,----,---,----,---,----, 

·0L----L----,~0----~5--~ --~2~5~--~-- 35 

Figure 25. Ratio of 1975 calibration to 1976 calibration for longtube Gardner coun t e r SNl143 as a 

function of scale r eading. The 

ordinate value was calcul a t e d from 

the ratio of the Hoerl's equations 

for 1975 and 1976. 

In an effort to d efi ne a clean air direction for Barrow in 1976, 

monthly and annual means of Aitken nuclei mea s ured with the Pollak 

c ounter were ca l c ul ated as a functio n of wind direction. It was found 

that the northerl y direction wa s significantly contaminated, and that 

the c lean air sector probably s h ould be redefined to include only winds 

from the northeast, east, and southeast. This was sugge sted by Emerson 

Wood, Barro~ .... Station Chie f in 1976. The recorrunendation \>1a5 bas ed on 

his o wn obs ervations of activity upwind of the observatory and is 

co nfirmed by the data given in the wind rose of Figure 26 and the 

monthly mean s for the clean air sector shown in Figure 27. 

f-lumb{! f 01 Qb $( rv al iom • 

to Gi ~·f! M!'m Il;'Ior N 

G;,'~n Wll1d Dlll!CllOn Jl 6 

\ \'V'fl'V'V .-----------.-. 

0 ::; 74 

]27-

,o,:('en t:uc...us COIlt:l'1'II1.\I IOIl 

10 . 

'. 

~,.. t Of OII S('I",1: LI;ms 

\Oll!n 1,V m:fs rr0l11 68 

G .'tlfi Dlfl!'C.lIon 

70' 01 WlnrB irQfl1 

CI ... .Ifl "I.r D'I\;t lI011 

A\' l!t<fl ~ AH ken " 1!)4 

."" 231 

'0 

563 

Figure 26. Darrow wind rose and geometri c means of condensa tion nuclei 

measured with Pollak counter SN16 

for 1976. 

44 

1000 - ------------_____________ ~ 

i 

oJ 100 

z 

, 

" I \ I 

\ I 

< 

1976 --

// j \ I j V 

I 1975 ---

1 0 '-;--~--;-;---~___::____, :___.,.__:__-=- ---' JF MA I\ l AS O :-J D 

MO·\lt· 

Figure 27. Monthly geome tri c means 

of condensation nucl ei measured 

during clean air conditions (NE, 

E, SE) a t Barrow during 1975 and 

1976. These means t.-lere calculated 

from Pol lak and Gardner counter 

observa ti ons . 
Figure 26 gives wi nd rose and condensat ion nu cleu s me ans as a 

f unction of dire c tion for all o f 1976. Many of the obse rvations taken 

duriDg no rtherly winds ~" re labeled co ntaminated and were no t inc lud ed 

in the means . Figu re 27 shows monthl y geometric means for 1975 and 197 6 

includ i n g only data taken during winds from the northeast, east , or 

south east. For most of 1976, cond ensation nu cleus means are as mu c h as 

100% high er than t h ose o f 1975. However , perhaps a careful screeni n g of 

the data ca n elimina te the possible local effects. 

Highly variable nucleu s concentrations , even under clea n co ndition s , are highest during March, July , and August, a nd lowest during 

June, September, and October of each year. Although a numb er of possible na tural and manmade a erosol sources have been identified for the 

Barrow site , it is often difficult t o identify t h e spec ific so urce. One 

possible so ur ce is the Ar ctic h aze whi ch is known to occur in early 

spring. However, human activity also increases upwind from the station 

during this period because of sunup a nd warmer temp eratures . (Note t h at 

large concentration s occurred in March for both years.) Human activity 

east of the station de c reases markedly in June because of t he melting 

ocean ice and t h e n picks up again s harply in July and Au gu st when the 

coastal waters are open for barge traffic. At the same time, there are 

ma n y documented measurements of large aeroso l concentrations (-3000 - 3 ) 

during app arently uncontaminated offshore winds and clear sunny co ndition s in March. These events are apparently assoc iated with clear, 

s unny conditions followi n g fog, or with an unusual upp e r level wind 

flow. 

A G.E. condensation nucleus counter was installed at Barrow in May 

1976 and produc ed re liable data f or the remainder of the year. All data 

wer e recorded by the Barrow data acquiSition system and are avai lab le on 

magn etic tape. 

A four-wave length nephelome ter was installed at Barrow i n Hay 19 76 , 

but there were problems with its thermoe le ctric cooler. However, 

approx i mately 5 wee ks of data were obtained in May and June. The data 

suggest that very l ow values (-10-?m- 1 ) were sometimes obtained in 

Barrow but that most of the time the ligh t scattering was between 10- 6 

and 10- 5 m- 1 . It shou ld be mentioned that t he ocean was opening up 

during this t ime and many of these data may have been ta ken on a marine 

aeroso l. 

4S 
4.3.3 Samoa 

Lo ng-tube Gardner counte r SN912 was op e ra ted twice daily during 

uncontaminated conditions throughou t 1976. Observations were taken from 

the 15 m level of the Univers ity of Rhode Island t ower on Cape Matatula. 

Figure 28 gives a wind ros e for the annual geometric means of co nd ensation nu c leus concentrations. Figure 29 give s monthly geometric means of 

all unco ntaminated ( n o obvious l ocal so urce) obse rvati ons" . Although the 

wind ro se shows slight ly highe r concentrations when the wi nd is over 

l and f rom the west or sou thwest, thes e observations are few and do not 

bia s the monthly means given in F igure 29. All monthly mea n s were a lso 

cal cu l a ted as a function o f wind direction, and in all case s the same 

a nnual trend of slightly highe r concentrations in the austr a l summer was 

observed. Nu cleus values in Figure 29 are tabulated in Table 11. 

Number 01 ObseI'Va lio ns ! to Gille Mean lor Give n Wind DirectIon 45 

\ \Q.,\§§) -" - ' - - " 

11" 18 / <Jfl~'- -. -' -/ 

\ 

,/ 

Aitken Nucleus ' 

Concentra tio n 

--------

J2 

Ave raye Ai tken ~ 

23 1 em ') 

· 32 

40? 

. - 153 

129 

Percent 0 1 Observa tion s 

with Wlll,ls from 

Gillen Dir eC tion 

~ 1= 1:----------------------- IOO ---------------------- --~-- ~ Jan Feb Mar Ap , May kn Ju l Aug SCI) OCl r .. nv c 

i1'10 1l \ h 

46 

Fi g ure 28. Samoa wind rose and 

geometric means of condensa t ion 

nu clei measure d with Gardner 

counter SN912 fo r 1976 . 

Figure 29 . Mont h ly geometric means 

of condensation nucl ei at Samoa 

during 1976, me as ured with l ongtube Gardner counter SN912 . 
rable 11. Condensation Nucleus Concentrations at Samoa 1976 

Jan feb Mar Apr May Jun Jul Aug Sep Oct Nov Oec 

-* X 314 332 299 25 0 239 205 180 221 198 218 193 195 

log X 2. 50 2.52 2. 48 2. 39 2. 38 2.3 1 2. 25 2. 34 2 3D 2. 34 2. 29 2. 29 

log 0 . 17 . 10 " .14 . 13 . 15 . 17 . 19 .15 .15 . 20 . 16 

n 20 22 35 31 33 49 41 40 33 40 38 24 

* -3 in nuclei cm 

During 1977 a Pollak nucleus counter, a G.E. automatic nucleus 

counter, and a four-wavelength nephelometer will be installed in Samoa. 

Long-tube Gardner counter SN912 and the Samoa Pollak counter will be 

compared to establish the ca libration of the Samoa long-tube Gardner 

c ounter . 

4. 3 .4 South Pole 

Pollak counter SNlS and the G.E. automatic nucleus counter continued t o operate at South Pole station throughout 1976 . During June and 

July 1976, the South Po le observers discovered a contamination problem 

with the Pollak counter which was repaired on July 28 . In an attempt to 

understand the prob lem and re cover the data, simultaneous readings of 

the a.E. CQunter and the Pollak counter were plotted as a ra tio for all 

of 1976 as shown in Figure 30. If both instruments were operating 

perfectly, this diagram would show a horizontal line at a ratio of 1 for 

the entire year. However, assuming t hat the Pollak counter is correct 

and that the G.E. counter may exhibit some offset with reduced sens itivity at the low end of the sca le, we would expect the ratio of Figure 30 

to be near 1 at the beginning of the year, increase in value during mid -

year, and return to near 1 at the end of the year (nucleus concentrations are very low during June and July). It is apparent from Figure 30 

that the Pollak counter probab l y began deterioratiug sometime in Ap ril. 

Therefore, it was assumed that the Pollak counter was operating 

properly duri ng Jauua ry to Mar c h and August to December. A compa rison 

and a linear regressi on were run on the simultaneous G.E. and Pollak 

counter observations for these months (F ig. 31). Several equations were 

tried in the linear regression, and 

log y = 0.9000 + 0.3914 log X + 0.08515 (log X)2 

was the be st fit, where y is the G.E. counter reading and X is the 

Pollak counter reading. This equation was inv erted and applied t o the 

G.E. couoter data for April to July, to recover midyear nuc leus va lues. 

The resu lts of this correction proc edure, along with 19 75 Pollak counter 

data, are shown in Figure 32, where data for January-March and AugustDecember 1976 are from the Pollak counter, and data f or April-July 1976 

47 
• . , .... ~ .. It _. 

, '. ... -.-

I I I I 

, .. " ... .. • f. ' • , ... .~ -\ ,c., .. '1''' 

..'" t .. _:"t."" ,. \ .. .." .. "." ....... J-:".... .. .. " .V .. .. ,... .. 

! I I ! I 

• • , . 

, . 

, 

, 

, 

, 

~ .. , ...... ..... .. -.. , .' ..... /I 

• • .. ".! ... '\ .: 

' . o 

.. • , " .. .. 

•• 

o~ 

, , , 

. 

• 

....... 

.. ,.,' ... W' 

'" ")' .. .. " o -. 

I I 

-

I f-- • , "', : .. ' ,,:: .. I.:' .. .. • .. .. .. .. .... o -- " .. .. '''.' .. . ' . .. :'1" .. ,', .. 

.. ..-:,. 

... - .. '. ..,.', .. y.. .. .... .. .,....... .. 

" .. .. . ~.. .. \.. .. .. .. -,. ".' .. .. .. .. \.' .. . ..... .. :-'\11 ... ,. : .. ',.! .... .. .. I '. , o " •• 

: ~ ~.' ' .. .. '''r ':Y'" 

~~'~ Jii" r"l1 ~I l,;r Apr t,l d" ~i~:~'~t~~~~ .Iull Jul ~~I~I~~ AU!I S("fl OCI I~I\lov ~I~ D ec 

l.!unth 

Figure 30. Ra tios of all s imultaneous G.E. counter and Pol lak counter obs e rv a tions a t So uth pol e . Two observations pe r da y during all of 1976. 

M 

5 

z 

"' " 

100 

Loy y " o.g · 0 39 144 Log ,oc . O. OG&1 (1erp~i 2 

u '" 0 W53 

IO ~~~---- ---- -- ~----~~ 1 10 ' 00 1000 

PolloK~ SN 15 N ~1 3 

48 

Fi gure 31. Compari son between Pollak 

count er SN15 and G.E. c oun t er a t 

South Pole f or J anu ary to Mar ch 

and August t o December 1976 . 

Solid cur v e s hows linear regr ession c urve us ed to calibra te the 

G.E. count e r. 
M 

, 

5 

- - - 1975 

100 -----.. ---1976 

10~Jan Feb ~~~~ M ar Apr M",v JU~~~~~~~~~ I'l Jul AU9 Sep Oct No.., Dec 

.'orll h 

Fi gure 32 . Monthly geometri c means 

of condensati on nuclei at Sou t h 

Pol e du r i ng 1975 and 1976. 1975 

da t a a re all from pollak counter 

SN15. 1976 data a re from the Pollak coun t er for J a nuary t o Mar ch 

and August to December and f rom 

corrected G.E. d ata for April to 

Jul y. 

a re correcte d G. E. counter data. Monthl y nuc le us data for 197 6 are 

nearly t he s ame as 1975 nuc l eus data. 

G.E. counte r data were re corded for the enti re year by the So uth 

Pole data a cqu i s i t i on system and a re s t ored on ma gnetic tape. These 

data ha ve be en c or r ec ted using a comparison o f t he G. E. counter and 

Po l lak c ounter on a mont hly ba sis a ccording to t he re gress ion equa tio ns 

given in Table 12. 

Dail y aeroso l ob s e rvation s along with temp erat ure and wi nd data are 

shown in Figure 33 for August-October 19 76 . This is an i nteresting time 

pe riod since i t spa ns some of the very c l ea n peri ods t hrough s unup t o 

the hi gher nucleus concentra t ions a t yea r 's e nd. 

Ta ble 12 . Corre ct ion s t o C. E. Co ullter Data at South Po le, 1976 

Month Eguat io n for Correcting Dat a 

J an log P = 0. 0314 0 + 0.9289 log G 

feb log P O. 44 68 + 0. 7448 l og G 

Ma r log P = O. 1592 + 0. 8956 log G 

Apr 

May log P = -8 + j 82 4 A (C - log G) 

2A 

Jun 

whe re A = O. 08515 8 = 0.3914 

Jul C = O. 9000 

Aug log P = 0.9523 ... 1. 443 log G 

Sep Jog P 0.8375 + 1. 378 l og G 

Oc t l og P = 0. 5274 + 1. 287 l og G 

Nov log P = 0.42 03 + 0.8931 log G 

Dec log p = 0. 07720 + 1. 070 log G 

G = G. E. data poin t in nucl ei 

p Correc t ed da ta sc aled t o Pol l ak count er cal i brations 

49 
"''''0 If ,f~.r<""',--",~~~o..,.....-d fif! 111',,--""'-/ / <~",.-.-...,_",~", .... ",---"fl /~.-.-/.r' if", 

~ ~~f 100 

M 

3 10 z 

2 3 <I 5 G 7 8 9 10 II 12 13 1<1 \ 5 16 17 18 19 202 1 n 23 24 25 26 27 28 29 30 3 1 

M 

z Seplembe, 

IO L-~~~-L~~~~L-~I~~~L-~~~~~~ ~~~ ~~~~~~~~ 1 2 3 4 5 6 7 8 9 10 II 12 13 14 15 16 17 18 19 20 2 1 222324 2526 27 28 29 JO 

M 

~ 100 

2 

OC lober 

L- ~~-L~~~~~~~~ ~~~~~~~~~ 2 3 <1 5 6 7 8 9 -: 0 11 12 13 \4 15 16 17 18 19 20 2 1 22 23 24 25 26 27 31 

Figur e 33 . Condensa tion nuc leus concentration at South Pol e for sel ected 

months of 1 976, with outside temperature and wind for each observa tion . All 

observations were taken with the Pollak count e r at about 0700 or 23 30 GMT. 

50 
4.3.5 Cooperative Programs 

In cooperation with the Canadian Department of the Environment, 

long-tube Gardner counter SN1176 was placed aboard the Canadian Coast 

Guard Ship Vancouver at ocean station tlPapa" in the northern Pacific at 

SOoN, 14SoW, Nucleus observations were taken fou r times daily at 0300, ' 

0900, 1500, and 2100 Greenwich Mean Time (GMT) for the periods December 

8, 1975, to January 8, 1976; February 16 to March 28, 1976; May 10 to 

June 20, 1976; August 7 to September 12, 1976; and October 20 to December 5, 1976. This program was conducted at the request of William 

Elliot of NOAAjARL and should provide an excel lent time series of data 

at a single ocean based point. Most ocean aerosol studies previously 

have been conducted from moving ships. 

Also during 1976, an experiment was conducted in cooperation with 

Keith Bigg of CSIRO to sample the Barrow aerosol. This sampler consists 

of an impactor-electrostatic preCipitator arrangement to capture particles directly on electron microscope grids for chemical analysis. Dr. 

Bigg!s technique is especially sensitive to sulfate and sulfuric acid aerosol. The results of this experiment sho uld be available sometime in 1977. 

4.4 Meteorological Measurements 

4.4.1 Meteorological Sensors 

In January, the standard meteorological sensors were installed on 

Cape Hatatula, Samoa. These included an aerovane to measure wind direction and speed, a static pressure transducer, a mercurial barometer for 

pressure, and linearized thermistors to measure air and soil temperatur es. 

Within a month of installation, the relative humidity sensor (humidicap) 

fai led because of salt-spray corrosion. Attempts to clean the sens or 

also fail ed. The replacement sensor lasted only a few weeks, so the 

operation of this humidity sensor was discontinued. Until a new sensor 

is installed, the humidity will be reported from a hygrothermograph. 

The failure of the relative humidity senSOr at Samoa was followed 

by the failure of the unit in use at MLO. These elements wi ll be replaced in 1977 with linearized thermistors inclosed in a lithium 

chloride-coated bobbin. Although the sensor has some drawb acks, it does 

have a ±1° accuracy from 0° to 25°C. The accuracy decreases markedly 

below 5°C, rendering the sensor usele ss in the Arctic. The dew point 

thermometer (Cambridge Systems) will continue to be used at the Barrow 

station to measure the moisture content of the air. Other methods will 

eventually be used at South Pole. 

The voltage amplification of the wind speed trans lator was found to 

be in error, partly becau se of design errors and a poor choice of calibration voltage. The errors were sma ll at wind speeds less than 20 m s 1 

A new calibration voltage wa s imposed, and the performance of the unit 

was linearized to about ±1% for wind speeds fEom 0 to 40 m s-l. The 

circuit was found to saturate at about 45 m s 1 A new card, linear to 

60 m s-l , will be suppl i ed in 1977. 

51 
% 

J F M A M J A S o o o 5 10 15 20 25 

Fr que cy 

(" ) 

D N 

<10 NE 

CJ E 

>10 

LJ 

SE 

S > 20 

sr'. 

I 1 1 1 1 ! 

I I 1 1 , " 1 ./ - 1 1 L_ '- -- 5 r lS" .. / - ~ Wind Dirce ion 

5 ms- I ~ --..,. 5 ms" Frequency 

-- C-.-;;:~ ;,.. - I I ""-1 i .- ~ r, p I 

~ -,;;~ j', / / "- --'I -.. , 

"'/ I '- --- 1-1.: -- - -~ I-

.-... _ .. '-t-' \.... - --- h / 1-- . ( 

=F= 

,. - l."'f'\ '" j """- R pI I - ... -~, ff " - .- ~ 5 ms 1 __ , r-: .... f--" 1-' ... ... f-- ' 'j 1 , I --

N 

NE 

E 

SE 

S 

SW 

IV 

NW 

1 r r-,. r-_;; ~- - r- '~ Average \-Vind 

!-" P Speed For Each 

r--' - - r-:sms1 .,.-1""" ---, 5 ms·l - - ~ 1 Dir~ctio,~ - - - "" I '. ! 1 1 i / 1 I r- I rW 

NW 

%8 @)e<9@§ 8 @)§<§@@ o 5 10 15 20 25 

mr' 

Frequency o f Ca lms for Each MOnlh 

1""91 Wind reed r Eac,' MOnr I- I II 

A M J J A S o N o 

Figure 34 . Surface wind climatology for Mauna Loa , 1976. Contours 

represent freq ue ncy of occurrence of wind direction in each month . 

Bar graph shows frequen c y of occurrence in the whol e ye ar . 

4 . 4.2 Ma un a Loa Meteorology 

Figure 34 summarizes the surfa c e wind data f or e ach month of 1976 . 

Although there is clearly a prevailing wind from a southe asterly direction, it doe s not occur as frequently a s does the prevailing direc t ion 

at other stations. There is also more variation in the wind direction 

climatology on a month-to-month basis at Mauna Loa than at o ther obs ervato r ies. In the fall , for example, the mo st fre quen t wind direction is 

s outhweste rly. A s imilar s hift occurs in March. The high est wi nd speed 

coin cides with the s outhea sterly winds, a nd the a v erage spee d for the 

year was 4 .7 m s -1 . Th e wind iest months were J a nuary and February. The 

annua l average of calm conditions was slightly more than 1% of t he time. 

Pro no un c e d variati on in the meteorological parame ters occ u rs on a diurnal basis. In futur e reports the statistical nature of the se variations 

will be shown as a fun c tion of season. 

On an average of 10 sound ings per month, the planetary boundary 

layer exte nd s above the level of llLO (see F ig. 35). The layer is 

deeper i n the winter and spring tha n i n the s ummer and fall. Th e wind 

direction within the layer is predominantly from the east , 26% of t he 

time i n 19 76 (see Fig 36). The flow is seldom from the west. The trade 

wind is steadiest during the s ummer months . The average vector wind 

s p eed for the lay er wa s 4.8 m s - 1 

S2 
t i 

• II 

,. I 

:', ., 1 -J ~5 ~~ L~'~' 3~'~ ~I~~~ -- "~~~"~~'~ ~30~-" 

I, 

J dn Fe" ".'If IIp M".,. J .. n 

I 

t I 

I • I I 

30 " 31 " 30 " kJ~'~ --~3I~ " 31 

J'JI Auq S~ , 0" ~o,' OK 

Fi g ure 35 , Th e gradient wi nd laye r (850 mb) as plotte d from the 1976 

Nr'lS H.il o rat-linsonde data . The vert i cal bar s s how t he height and 

thickness o f the l ayer . 

F M A M J J A S o N o o 10 20 30 40 50 

NW NW 

' 0 

(' "'\ -.. / / ~ 

~ \ .'\." .L \.. 20 1' J 

) V/ ~ ,/ ./ } // 

....., 

r- ./ V \" 

--- '" 7, ..... r-- I' 1 0 ( - I' ,63r- \. " '- ./ ,..... " tN 

NE 

E 

N 

NE 

E 

1= 

f::J0 

J :-- ...... 

I ....... / I \ I SE = SE F> \ 

\ 

f-"" L """\. I '" I 

I-' t ./ \ / 

,- -\ 

S 

SI' 

S 

sw 

- Wind Direction 

~ Froqu,,,, 

W i--- w 

Ni\ I 

-. 

NW 

-

I I II 

A M J A S o N D 

Figure 36 . Clima t o logy of the plane tary bounda ry la yer as de termined 

fro m t he Nr.-'S rawi nsonde data from Hilo I Hawai i I in 1976. The Hi l o 

station is 55 km northeast of MLO. Contoul.·S represent fr e q uency 

of occ urr ence of \.,rind direc tion i n per c ents . (See lege nd I Fi g. 34 .) 

53 
Jet Stream Wind Observations 

On many occasions the air reaching the Mauna Loa Observatory 

during the night and early morning hours comes from the upper tropos phere. Figu re 37 depi c ts the variation in height and thickness of the 

jet stream layer in the v ic inity of t he observatory. Although t he 

bottom o f the layer extends below 6 km -28% of the time. it seldom 

rea ches the ob serva t ory at 3. 4 km or the top of t he f'launa Loa vol cano at 

4.2 km. The most frequent wind di rec t ion in this laye r, west , oc curs 

46% of the time (see Fig. 38). East and southeasterly winds occur 

infr equently. The average vector wi nd speed for the laye r is 19.2 m S 

1, with the maximum s peed s oc c u rring in the spring and the minimum in 

the fall. 

5 15 

,., )I A" ., )I " 30 

I. D"' 

Figure 37 . The jet stream " ind layer as plotted from t he N~/S Hilo 

rawinsonde observa tions during 1976. The vertical bar s depict the 

layer through which t he wi nd direction cha nges less than 22 0 fro m 

th e di r ection a t 250 mb. 

54 
4.4.3 Barrow Meteorology 

The GMCC observatory at Barrow is about 9 kID from the IIpoint!l, the 

northernmost extension of the Alaskan north slope. For 300 km the north 

slope is void of topographic barriers that could influence the local 

wind flow, For most of the year the winds are the result of synoptic 

scale weather systems. Between stormy periods, when the wind can blow 

from any direction, the local winds are controlled by the outflow from 

the polar anticyclone. This situation results in a persistent easterly 

wind at the surface. The most significant local phenomenon is the onset 

of the stratus cloud layer along the coast in the spring. The time of 

onset corresponds with the time the sun is up for most of the day, when 

extensive leads open along the Arctic coast. 

The seasonal variations of wind speed and direction are displayed 

in Figure 39. Although easterly winds are those most commonly observed 

all year, they are most prevalent in the spring and summer. In the 

stormy spring and fall months, the prevailing wind is more northerly. 

Southerly winds are relatively uncommon, occurring less than 10% of the 

time. The seasonal variation in wind speed, although not too pronounced, shows a slight increase in the spring and fall compared with 

the summer and winter. The average wind speed for the year was 5.2 m s 

The maximum wind is easterly. 

"'" E 

NW 

N 

c--

NE 

E 

SE 

S / 

sw I 

/' 

W 

NVI ' l30 

20 

10 

o 

J 

M A M A S o N o 

V \ 

/ '\. / \. 

/ r--- r-...... 

/ ""\ 

I 1b \ ./ 

-...... ,10 

V 20 ........ :--.... /. ::--0. 

/' ;::=:;i f- 30 -. :::--F0 

jf, -C- 6 0- ~ 40 4,. 1 L"; o p-,.: ~ t 

/ L i":-

t--- I 

/' , '\' 1 

.,/" ;--... ...... f-. 

Average Wind Speed for Each Month 

F M A M A S o N o 

o 10 20 30 40 50 

I: --~ NW ~ 

N 

::;-

NE 

E 

I---- I-- -

~ Wind Direc t ion _ 

ct- FrejUency I -

SE -$ 

S 

I, 

I 

SW 

W 

-

1 

NW 

Figure 38. Climatology of the jet stream wind layer as deterrrdned 

from NWS Hilo 1976 rawinsonde data. Contours represent frequency 

of occurrence of wind direction in percents. (See legend, Fig.34.) 

55 
In 1976 the NWS offi ce a t Barrow reported a maximum tempe r a ture of 

17 °C on July 29 a n d a minimum of - 41°C on February 26. They also 

r epo rte d 188 cloudy days ( 8 / 10 and grea t er cloud cover), 65 pa r tly 

c l oudy days (2/10 to 8/10 cloud cover), and 47 clear day s (less than 

2/ 10 cloud cover) . Afte r leads open in the Arcti c o c ean i n the s pring, 

a pers i s te nt stra tus deck covers the coa s t, In the 6-month period MayOc tober, o nl y eight clear day s were o bserved--141 were c loudy. Thus, 

77% of the time the cloud cover excee d s 8/10 . Although the se ob s erva -

tions are made at the Barrow airport 7 km southeast of the GHCC s tation, 

they are generally rep re sentat i v e of the Po int Barrow region be c ause of 

the uniform nature of t he s urro unding terrain. 

4 . 4.4 Samo a Mete o rolo gy 

The GHCC observatory i s on Ca pe Nat a tula, the most northea s t erly 

extension o f the island of Tutuila. The s tation i s at long. 17 0 0 W. I 

lat. 14° S . I and 80 m above mean s ea l eve l. Tutuila i s a long , na rrow 

island of volcanic origin, with its lnajo r ax i s lying in a so uthwe stnortheast direction. Its great e st l ength is 32 kID , and i t s wi dth 

range s fr om 1 to 8 km. The highe s t peak i s 0 . 65 km. 

Frllquenc y % 

I'!II F ~ , A M J A S o N o o 5 '0 '5 20 25 

0 

<, 0 

0 

>'0 

>20 

>30 

-! J I , I 

N I \: ~ '-. //'-r iOo.."'. V INE 

E 

,- 1/ """\ ~; " ... ~\. I-

~ ~ 

~~ ( 

'_. ~ 8!!i 

K "\ // 

I 

I '1\ 

J ..... ~ 

SE V -- ,- --- [/ "\ 7 

S 

SW 

N 

- ~ m," 

--, " \ ,-

~--; ,< j.-' I " 

:: ". , 1\ I-j" ;. ( / I \, ) l:; i--- :5 m: ',', / f..- - "0- i ' 

-....: fJ- --!- - t-- ._ j.- NW I.- "/ 1-- )-... 

FreQue ncv o f Ca lms fo r Each Mo nth 

i d 

Average Wind Speed for Each MOlllh 1 I ! I 

M A M J J A S o N o 

f=! I-wlnd 6i,cc:ion 

~ Jr?l

u

•

ncv 

N 

NE 

-f--

E 

I- SE 

S 

h 1\ SW 

II It""" Wind Speed For Each 

IDireT tionl 

N 

NW 

o 5 10 15 20 25 

ms- 1 

Fi gure 39 . Surf ace wi nd cli ma tology for Barrow, 1976 . 

(Se e legend, Fi g. 34. ) 

56 
The regularity of the trade wind at Cape Hatatula in 1976 is 

clearly s hown in Figure 40. The wi nd blows from the east-southeast 

direction almost 25% of the time throughout the year. There is a 

slight s hi ft to a more northerly direction in the austra l summer months. 

The stronger winds are also associated with the trade winds. The wind 

speed is recorded as calm about 0.3% of a given mo nth . The average wind 

speed for 1977 was 6.5 m 5- 1 . The maximum wind speed in 1976 was well 

in e xce ss of 4 0 m S-l and was associated wi th a passing tropical disturbance. 

Th e tropical disturbance that pass ed Cap e Matatul a on Decemb er 11 

wa s the outstanding meteorologica l eve nt of the y ear. Th e wind did 

consi derable damage, ca u s ing the sampl i n g tower that s upp ort ed the 

station anemometer to collapse. As a result, a record of peak gust 

during this storm is missing. Wtthin 3 h ours the pressure dropped 20 mb 

to a minimum value of 973 mb. 

Frequency % 

(%1 J F M A M J A 5 o N D o 5 10 15 2 0 25 

CJ <10 

> 10 

>30 

> 40 

--;-

\ N .' ./ 

NE 

E t. ~ .... -c' ~- ' ~ ~- -- SE ;:~ '" 

.5 ",,1'- - '\ 

' .. -~' S 

,. 

W 

NW - =-_5 :"" 

IbJ \" " I 

Frequency of Calms for Each Month 

12 

8 "'-

" 4 ~ - -- Average jWind ~peed f?( ac ~ Mont7 

o 

J F M A M J J A s o 

~ 

"-

~~ 

.:::l 

-" 

/ 

N o 

1= 

1= N 

- Wind Direction NE 

Frequency 

E 

SE 

~ 

7"- 5 

'-- Average Wi nd 

Speed For Each SW 

- Directloll 

w 

NW 

o 5 1C 15 20 25 

ms-1 

Figure 40. Surfac e lvind climatology for Cape Matatul a I American 

Samoa. (See l egend, Fig. 34.) 

57 
4.4.5 South Pole Meteorology 

The local meteorology at the South Pole is strongly co ntrolled by 

persistent radiation inversions · and kat aba tic winds. The inversions , 

which can be extremely s trong, especially in the winter, effectively 

separa te the s urface layer from conditions aloft. Only during the 

middle of the s ummer season and during brief stormy periods doe s the 

invers ion weaken, and at best an isothermal surface layer exists. 

The station is on the high, locally flat Antar c t i c Plateau at an 

elevation of approximately 2800 m. The katabatic wind s flow from the 

east (i.e., long. 90° E.) off the ridge of the plateau, which is located 

in east Antarctica. However, during sto rmy periods with wind speeds 

above 10 m 5- 1 th e wind direction i s pr e dominantl y from the north 

(long. 0 °) or within 20° of either side of north . Thus, it is these 

high-spe ed winds from grid north that are respons ible for most of the 

loca l drifting. 

During the austral fall and spring of 1976 a few new temperature 

and pressure reco rds were set. However, the monthly average temp erature 

clo s ely foll owed the climatological average of the past 20 years . One 

marked exception was Augu st , which was the coldest month. The average 

temperature was about SoC co lder than the climatological average (see 

Fig. 41). The coldest recorded temperatur e , -76°C, was also in August. 

Th e wind and temperatu re sensors were in the same l oca tion throughout 1976 as they we re in 19 75. Th a t location was about 100 m grid 

northeast of the eastern edge of the main stati on. The anemometer is 

abo ut 10 m above the snow surface. The thermome ter is only 1.5 m off 

the surface, 

Changes in the wind climatology fo r 1975 and 1976 were small. The 

relative distribution of wind direction was less concentrated in the 

grid e asterly components in 1976 (see Fig . 41) . The most common wind 

dire c tion was fr om grid north-northeast, We s terly winds were observed 

about 20% of the time. This contrasts with only 11% the previou s year. 

The average wind speed for the year was 5.2 m s 1 Calm winds were 

report e d o nly 2.5% of the time . 

58 
Frequency 

(%) 

CJ 

<10 

CJ 

> 10 

D 

>20 

J F M A M J A s o N o 

I -

, " "-' / · S ms· 1 

'- N 

-~ '- ~I t' ~ ~ 

If ,- 5 ms· ~ '\. \ { ,- \ h ~ "......., '"" 1.---"'" -, " ": ~-~ ;.., 

NE 

k' ~ ..... , I,/J -.. ~ ~ ~(" 

- I E 

SE 

r; ~ 

~ H S 

, SVI. \ 5 ms·1 

-

W 

-I - 5 r:n s·1 - ... ... • , 

I 

NW 

Frequency of Calms for Each Mo nth 

./ 

~ Air Temperawre fo r E. ach Month 

"-. V 

"'" / 

I 

J F M A M J J A S o N o 

% 

o 5 10 15 20 25 

f- h N 

~~~ ~- NE 

E 

+ 

::; Wind Direction SE 

3- Frequency 

' I ::J I I I S 

= ~ ve ~e W~nd SW ~ SJ.)eed For Each 

Direct ion 

w 

~ NW -, 

o 5 10 15 20 25 

ms-1 

Figure 41. Surface wind climatology for Amundsen-Scott stati on , 

South Pole, 1976. (See legend , Fi g . 34.) 

S9 
4.4.6 GMCC Trajectory Program 

The GMCC a i r parcel trajectory prog ram became fully op e rational 

during 1976 f o r s tations in the Northern Hemisphere. Th e wind data, 

which constitute th e basic input to the computer program, ar e derived 

from two sources: obs e rved winds (available every 6 or 12 h o urs) fr om 

th e global upper air station network, and analyzed winds (availabl e 

every 12 hours) from the Nati onal Meteorologi ca l Center in Suitlanci, 

Md., 65 x 65 Northern Hemis phe re grid. Ba c kward trajectories ar e 

comput e d routinely every 6 ho urs for the following s tations. (They now 

have b ee n generated through Decembe r 1976) ; 

Station 

~launa Loa Ob se rvato ry, Hawaii 

Barrow, Alaska 

Adrig o l e , Ire land 

Bermuda 

Ithaca , N.Y.; Hhit e Face 

Mount ain , N.Y.; Charlottesvill e , Va. j State Coll ege , Pa. 

Trajecto ry Type 

IO-day backward traj ec tory 

Analyzed wind o nly 

3000-5000 m ab ove t errain (msl) 

IO-day bac kward traje ctory ; 

Obs erve d a nd analyzed winds 

300 - 2000 m above terrain ( msl) 

10-da y backward trajectory 

Observed and analyzed winds 

300 -2000 m above t e rrain 

10-day bac kward traj ec tory 

Observed and analyz e d winds 

300-2000 m ab ove terrain 

5-day ba c kward traj ectory 

Ob se rve d winds only 

300-1500 m above terrain 

There i s ge nerally a 1~- t o 2~-month lag in r ea l time, mostly 

because of the comp lexity of assembl ing the obse rved winds. In practice, traj ectories of any length) avera ging layer and time period) can 

b e computed for any location in the No rthe rn Hemisphere. Th e validity 

o f the trajecto ries i s limited only by the quality of the wi nd data. 

That is, winds observed eve ry 6 hours u sua lly provide more r ealistic 

traje c tories than d o wind s analyzed every 12 hours. The data bas e has 

not y e t been exte nded to the Southern Hemisph e re, so similar comput a -

ti on s for Samoa and the South Pole GMCC s tati o ns have been deferred. 

60 
4.5 So lar Radiation 

Solar irradiance is meas ur ed routinely at all fo u r GMCC observa-

.tories as an integra l part of the long-range monitoring of benchma rk 

parameters. Eppley pyranometers and pyrheliometers are the principal 

instrumentation u sed for monitoring. Solar irradiances are measured 

over broad spectral bands as well as through narrow band-pass interference filters. The broad-band measurements are mad e through quartz 

and Schott glass cutoff filters where the mean wavelength windows 

measured ar!: qu::rtz, 2000A )' II )' 300QOA;_GG22, 3900A )' II. )' 30000Ai-, 

OGI, 5300A > II > 30000A; RG2 , 6300A > II> 30000A; and RG8, 6950A > II > 

30000A. The transmitta n ce varies slightly with ambient temperature of 

field observation conditions and with different filter production melts. 

The ultraviolet global pyranometers used in the network incorporate a 

diffusing disk as well as a fi lter with a window of 29S0A )' A )' 3850A. 

The narrow-band pass interference filters are u sed in the Eppley 13-

channel normal incidence pyrheliometers (NIP). 

4.5.1 Measu rement Program 

Table 13 lists the solar radiation measurement programs in GMCC 

through December, 1976. The Eppley filter wheel NIPs started a new 

normal incident solar irradiance measurement at all the observatories. 

Broad-band measureme nts are made during clear s ky conditions and the 

instrument is manually a ligned and pointed to obtain true values. 

Eventual automation of these instruments is planned. 

The Volz-type sun photometers are part of the EPA Atmospheric 

Turhidity Network. Measur ements through narrow-band pass interference 

filters of :10 run width at 3800A and SOOOA are mad e to monitor dust 

l oading (turbidity coeffic ients). 

Table 14 lists a ll the GMCC solar radiation instruments with calibration constants that were used to obtain measurements at the observatories during 1976 . 

4.5.2 Data Acquisition 

Data are acquired by two methods. First line data acquisition is 

by a NOVA compute r. Sec ond line (backup) acquisition is by a strip chart 

analog recorder. Both methods record signal voltages produced by the 

radiation instruments after they are amplified through a preamp bank. 

The NOVA computer provides processing of data, 

storage, and liD" array data conversion (see 4.5.3). 

recorder produces a conti nuous tra ce of the signal 

this record into engineeri ng units, an average over 

corrections for the zero offset and preamp gain are 

magnetiC tape data 

The strip cha rt 

voltage. To convert 

a time span and 

first made. To 

convert these corrected signal voltages into enginee ring units, the 

calibration constant is then applied. Figure 4 2 shows the schematic 

flow of measurement recording systems . 

61 
Table 13. Solar Radiation Measu rements up to January 1977 

In s trument Stations 

MLO Barrow Sallloa Sou lh Po le Boul de r 

Eppley 

py r anome lers 

Q global 

GG22 g\Ob<'l\ 

OG I global 

RGB globa l 

UV g l obal 

Eppley fi Iter 

wheel N{P's 

Q NIP 

OC I NIP 

RG2 NIP 

RGB NIP 

Eppley narrowand broad-ba nd 

NIP 13 Channels 

Eppl ey NPIS NIP 

Vo Iz Sun pholome ters 

Di ffuse (s hader) 

x 

x 

x 

x 

x 

x 

x 

*No thing on requl ar basi s. 

4.5.3 Quality Control 

x x 

x 

x 

x x 

x x 

prO . x 

x 

x 

x 

proposed x 

x 

Rema r ks 

J ust bequn lhis yea r. 

hand opera ted 

Di d not operate ,.,ell at 

South Pol e. 

On equalo r ia l lnlCker. 

Hand opera ted . 

Occul ting di sk traCk i ng 

sun and s hading py ranome le r. 

Table 15 lists our quality control proce dures. The NOVA da ta aC -

quisition system temporarily reco rd s instantaneous signal v o ltages in a 

"VIr array at I-second intervals. Thes e v o lta ges are passed on to an IIM" 

array where they are stored in I-minute voltage total blo cks on magnetic 

tape with observational scan tallies at IO-minute intervals . These same 

voltage totals and tallies are also stored in a "D" array. The voltage 

totals are c onve rted into hourly integr al s o f solar irradiance values in 

engiQeering units. These hourly integrals are also stored on magnetic 

tape along with all other comp onents of the tlD11 array. A calibration 

scheme and algorithm constants are ma intained and us ed in the "Oil array 

to c onvert t he signal voltage into solar irradiances. This is done by 

substi tuting test voltages instead o f s ignal v o ltages at timely intervals into the NOVA data acquisition sys tem . The data generated in the 

IID" arr ay are those used in Bou ld er to monitor instrument performan ce as 

well as those u se d for distribution. 

62 
Table 14. So lar Radiation Instruments On Line Durinq 1976 - ~--=-

Instruments Sta tion 

Mauna loa Barra,.. Samoa ~out h ~o C! Boulder NOV A Channel 

Eppley rd o~te rs 

Globa l OUar'l1. 

Seria l numbert l2616 12263 12273 In7l 12216 l' Ca l . con st ant .0794 .0956 . 09Z? . 1072 10204 

Globa l GGll 

Serid I number L0151 12265 12Z74 12268 12611 17 

Cal. constant . 0695 .0983 .0963 .10217 . 09398 

Globa l DC I 

Se r ia l number IO I SZ 12264 12217 12269 12618 18 

Cal . constant .0735 . 105 1 .0962 . 1036 . 0769 

Gl obal RCB 

Serial nulflber 10153 12267 12275 12270 12619 19 

Ca l . con5tant .0 767 . 0965 .0910 . 0978 .0791 

Globa l UV 

'" Se rial number 10232 12348 12349 20 

W Cal. con stan t 1.9084 l. 869 2.278 

Epp ley Pyrheli~eters 

Eppley NIP Q. Filler 

Wheel OGl r RG2 1 RCa 

Seria l number 13910 13913" 13914'" 13912* 13909 ,~ 

Cd I . constant . Oe25 , 0826 ,0829 ,0815 . 0774 

Eppley 8road -8and 

and Harro~ -Ba nd HIP 

13 Channe Is 

B8 Q, CG22, DCI, RG8 

Seria l number 47" 4757t- MLO Ch 21, ZZ , 26-31 to Oct 76 

MlO Ch 23-35 to Dec 76 

South Pole Ch 21 , 22, 26-28 

Ee:e:le:z:: NIP Quartz 

Seria l nui:lber 2119 2968 IUD Ch 23 to Oct 76 

Ca l . constant .0295 .0259 Ch 21 to Oec 76 

South Po l e eh 29 

Volz Sun ph t~eters 

Serial nuwer OAG38 OAD49 DA1l6 E4 640 OA l1 5 None 

te al ibr ation con stants are in (1V/r.'oI clll- 2 

* On line early 1977 

t- Terminated Oct 19 76 
Anal<'Q 

S!fI;,Ch.rl 

R .. r:OlThrr 

IV(l I~\ 

iOVA CoI'fl;:Jul h 

'.! ~ Tapt' Dau LOllgiry 

I n,\:cnr] SUitt' I VoU" 

1 rnrl'l:.rCC- ~\ln ll .1 10· 

m"1U! e In u::rv.I, IVa] l s) 

1 "' Ou r .lVc r"9t s En ym!!erINJ Unit~) 

,CJ' CI;I,m rl Amo Gd 'l~ 

Zt!ro OH!o;'; , 

Figure 42. Schematic flow of measurement and recording systems for 

GMCC solar radiation instruments. 

Table 15. Procedures for Quality Control of Solar Radiation Data 

1. NOVA calibration system 

2. Nighttime zel'O offsets 

3. Daily documentation sheets 

a. Instrument malfunction s 

b. Obstructions on instru nt s 

c. Sky conditions 

d. Instrument orientation 

4. Data examination 

a. NOVA computer plots 

b. Statistical analysis 

5. Instrument comparisons 

a. Boulder Laboratory intercomparisons 

b. Field intercomparisons with traveling standards 

c. Instrument history files 

6. Observatory feedback 

64 
In addition to the NOVA calibration pr ocedures , an i n s tr ument ze r o 

( r ecorded dark voltages) is applied to the h ourly averages o f so l ar 

irradi an ce. Th is proce dure is u sed to s ubt ract out all i nternal nOi se , 

dat a ()cq uis ition , and instrumen t offs ets that ca n be come si gnific ant fo r 

low sign a l volta ges at l ow sol a r angles. Typ1cal va lues o f the dar k 

volta ges can range f r om 0.0 to f O.S mW ern 2 

Ano ther quality control me as ur e i s a solar r ad iation daily 

me ntation sheet. An ex ample of the s hee t is shown in Table 16 . 

c hecklist d ocumenta tion is made by the observer in the field to 

doc uA 

reco rd 

instrument pe r formance , o ri e ntation , a nd repairs I as \.,Ie ll as s ky conditions and o bstructi on s on the domes . A tabu lation of two o f the 

entrie s is g iven in Table 11 . No t e that all o bse rvatories a v e raged 

c lear sky p e riods ( s ky clear fronl ho rizon t o horizon for 2 ho urs o r 

more) at l east on 33% of the days . 

Ta bl e 16. Examp le of Dail y Che ck Li s t Docume nt at ion Sheet for So 1 a r 

Radiat i on tieasurements at Amu ndsen-Scott Station -,--

Od lf! tJ~< 1970 15 i6 11 lB \9 

J N51~U !! I, I A 1! ON 

00l .' t) l]'Jl 001 OfJOOl 2130Z [IDudy 

Ori nt. ti O" of 

PI' l\i!tla/telef!o. 

(T i lle) 

Si,!!ul Cab \o luds ck 

Otl st ,-;>.J~ L1 a~ , on -~i.,· Fi lte r OOrttH 

Oe ss icant o( 

l he l Pyl'"llnOtr.llt.rr. o' 

il l.a .... ltr OPH.u iol' 

lJeat l' 1" 

BOSS - t CW·5 " Oata Seli n ' k 

Ttl etypl: Pri nl.olll 01 

Stri'f' Ctur\ Recorder ,. 

" N I A 

C1ear 51:: ies 

REHAR"S 00 'co 

(ol l €'ct il1g 

on dODe S 

"20.l0Z j" 

collec.ti ng 

on dOH S 

0 

O!alOl o k 

2030l 

•• 

Ol JOl 

"O!106Z 

"o-a t 5l 

o. 

., 

Ok 

: ., 

• 

" .. N A • 

{ 

:0 IJD~ - [: 1. ea nell 

ic e art iIkImu 

"O:;'OOZ ice 

on flOI1 (".~ 

"OBISZ c l ea red 

I,. of f 4<lm1l 5 

;} inyc st luating 

GG/Q nt-Io l. 

QG vs. QG std. 

discr epa rey 

6S 

(I ~-l 5l 10~(\ l 

2100n 

0' 0< •• 

ok ~2030~ 

ok " . k 

ok " o' 

., ., 

L " 

" I " " 

• ., , Ok 

Ok ., " 

" N , I • M " A I 0 " N I ' u 

J J I J J 

, 

I, 

~ re s e t F=4 '~l. !" c-a.l 1ut tng cloudy -

to corree t on d-arr.e s snow 011 

alu e5 -20]4)1 '" "r cleaned 

oft de s 

J 

, 
Table 17. Incidence in 1976 of Obstructions on Pyranometer Domes and Clear Sky Periods, 

From Data on Sola r Radiation Daily Documentation Sheets 

Ann(Jd 1 

Station Jan Feb Mar Apr Ma y Jun Jul Aug Sep Oct Nov Oec Tota l Avg . 

Barrow 

No . of day s checked 4 12 21 26 26 29 15 8 16 21 4 182 

Avg. % Of days 

obstructed 0 0 0 27 4 3 0 0 25 5 50 9% 

Avg. % of days 

w/clear periods 25 42 33 50 15 28 80 75 31 9 50 36% 

Mauna Loa 

No. of days checked 29 11 13 15 15 13 6 10 13 13 19 14 III 

Avg. % of day s 

obstruc ted 0 0 8 0 7 0 0 0 0 0 0 0 1% 

'" Avg . % of days 

'" w/c lear periods 76 45 15 47 87 54 83 70 54 38 53 57 57% 

Samoa 

No . of days c hecked 24 14 26 20 22 22 17 20 24 26 23 24 262 

Avg. % of days 

obstructed 0 14 4 10 0 9 6 0 4 0 0 0 3% 

Avg. % of days w/c lear periods 29 21 23 25 32 41 35 50 63 35 26 25 34% 

So uth Pole 

No . of days checked 15 6 18 4 31 30 31 135 

Avg. % of days 

obstructed 87 17 94 100 84 50 87 76% 

Avg. % of days w/c lear periods 67 0 6 SO 16 47 48 33% 
4.5.4 Quality Control Through Instrument Intercomparisons - 1976 

Like instruments were intercompared to detect any abrupt changes or 

long-term drift in instrument sensitivities. Several instruments were 

designated control instruments (standards) and were used as the ba s e for 

comparison. Intercomparisons were made at the Boulder office as well as 

at observatories in the field. In all comparisons the instruments were 

expo s ed to the sun under clear sky conditions and ambient temperature. 

Some data from cloudy sky conditions were incorporated into the comparisons at field sites only when not enough clear sky data could be obtained. All comparison results are determined from daily totals of 

irradiance. Comparisons for shorter time intervals are monitored and 

documented but are not listed in the tables of this report. Differences 

in response between instruments show a dependence on solar elevation. 

Any analysis of comparison data for time intervals shorter than one day 

should take this into consideration. 

With the ex c eption of the spectrolab global pyranometer standard 

maintained by the NOAA/ARL calibration facility in Boulder, all GMCC 

solar radiation intercomparison measurements in 1976 were made with 

Eppley pyranometers and pyrheliometers. The c alibration scale used for 

the pyranometer is based on the International Py rheliometric Scale. A 

multiplying factor of 1.026 i s required to convert the data to the 

absolute radiation scale as determined by the World Meteorological 

Organization (WHO), and measurements based on a Kendall PACRAD radiometer, serial no. III. The pyrheliometer calibration s cale is based on 

the transfers from an Angstrom No. 2274 pyrheliometer, a Kendal TMI 

absolute pyrheliometer (No. 67504) s tandard of NOAA, and a silver disk 

(No. 5178) pyrheliometer at the Davos , Switzerland, comparisons of 1975. 

The GMCC also maintains two standard pyrheliometers (an Ang s trom No. 

10180 and a Kendall No. P12843) that were intercompared at Davos. For 

the intercomparisons with the GMCC working pyrheliometer in 1976, the 

NOAA/ARL working NIP standard No. 1330 was used. It produces irradianc e 

value s that are 0.975 ±0.002 of the Kendall TMI No. 67502 irradiance 

values. To convert the data to the absolute radiation scale, a multiplying factor of 1.026 is required. 

Data for the calibrations at the field observatorie s were processed 

with the NOVA minicomputer and the BOSS 176 ICDAS software. The signal 

from each instrument was amplified before being processed by the computer, and hourly integrals of solar irradiance were determined and used 

to obtain daily totals of solar irradiance. 

67 
Da ta for the calibrations at the Boulder GMCC o ffi ce were pro cesse d 

b y a Hewlett-Packard 20 10 L data acquisition syste m a nd sto red on Ken -

nedy Model -1600B 7-track tape recorder. The magn e tic t a pes we r e processed through a CDC 6600 comput e r at NBS, Boulde r, Co l o rad o . Tw o -

minute averages of solar irradianc e we r e u s ed t o o bta in the da i ly 

totals used for the compa ris ons . 

Table 18 shows the r es ults of the pyranometer c omparisons at the 

GMCC ob se rva t o r ies i n 197 6 . The tra v e ling standard No. 126 1 7 was used 

a s the ba se i n s trume nt. Th e e ntry in the fifth column is the multiply i ng fa c t o r that c an b e applied to the data to normalize all the 

me a s ur e me nts t o iilstrument No. 12617. The 2.3% difference obs e rve d at 

the So uth Pole is questionable because noise was detected on the NOVA 

channel r e cording data from instrument No. 12617. 

Tab l e 19 lists the results of pyrheliome t e r comp a r iso n s at MLD. No 

standard instrument was used, but pyrhe liome t e r s a t the ob s ervatory were 

intercompared. Instrume nt No. 328 7 is r e t i red a nd i nstrume nt No . 2 11 9 

is still on line at MLD. Qu a rtz channel 12 o f the 13- c hannel radiometer 

in ope ration at MLD wa s a l so compared . 

Res ults of the qua rt z pyranome ter intercomparis ons at Boulder for 

197 6 ar e present e d i n Table 20. Both G~ CC and GATE instrume nts "ere 

. c ompa r e d. Lis ted ar e the calibration consta nts used wi th each intrument 

fo r the inte rcomparisons. 

Table 21 comp ares pyrheliometers at Boulder including the Eppl e y 

filter wheel NI P instruments that were incorporate d into the GMC C program this year. The base instrume nt i s the NOAA s t a ndard used by the 

ARL calibration fa c ility in Boulder . 

Table 22 lists the results of the Eppley pyrheliometer intercomparisons at Bo ulder for the quartz channel as well as for the filters. 

Instrument No. 139 09 wa s used as the base instrument. In the interc ompar i sons of each filter, the original quartz difference between the 

base instrument and e ach other instrument \vas sub tra cted from the 

differenc es observed with the filters. 

Table 23 summarizes the results of the interc omparison s between the 

standard (base ) instruments made at Boulder for 1976 . The differen c e 

between the Spectrolab and Eppley pyranometers may be mo s tly due to 

differences in instrument response at different so lar angles rather than 

to a drift in instrument sens itivitie s with a ge. More che c king will be 

done. 

68 
'" '" 

Table 18. Field Inte rcomparisons of Eppley Model r f Pyranometers With Quartz Wi ndow in 1976 

Observatory Ser ial No . Cdlibration 

(mV -1 * -1 Ly mi (1 ) 

GMCC Standard 12617 5. 65 

Mauna Loa 12616 5.54 

Samoa 12273 6.47 

Barrow 12263 6. 67 

So uth Pole 12271 7. 48 

* Ly ~ Lang ley ~ ca l orie em 

-2 

** GAT E In strument 

Constant 

-I - 2 (mV mW em ) 

.0810 

.0794 

. 0927 

.0956 

.107 2 

Ra t io of Oail y Total s: 

Ins l rument/ Compared 

12 ~I str ent 

I. 000 

0.9938 

0.9887 

0. 9936 

0.9769** 

Deviation From 

Standard 

(%) 

0.6 

1.1 

0. 6 

2. 3 

Table 19. Intercompa risons of Eppl ey Pyrheliometers With Quart z Window and 

13 -Channel Radiometer at Mauna Loa , June 8-24, 1976 

Seria l No. Calibration Constant Rat io of Dail y To tal s: 

-1 -1 - 1 -2 lnstrumen~compar d (mV Ly min ) (mV mVi em ) 21 1 Ins trument 

2119 2.06 .0295 1. 00 0 

3287 2.09 . 0300 I. 029 

13-C hannel Radiometer 4.48 .0642 I. 033 

4758-12 

Dates 

Apr 3-16; Apr 28-30, 

May 26-Jun 8 

Apr 20- 24 

May 5-18 

Nov 23-0ee 30 

Dev iation From 

Standard 

(%) 

2.9 

3.3 
" 0 

lable 20. Bou lder Laboratory Int ercomparisons o f Eppley Pyranomete rs (Model II Wi th Quartz Window) 

on Cloud-Free Day s, March 6-10, 19 76 

Ins trument No . Ca librati on Constant Rati o o f Dail y Total s: Deviation From 

-1 -1 -1 -2 Instrumenyicompared Standard 

(mV Ly min ) (mV mW em ) 10155 Instrument (%) 

10155 GMCC St andard 5.06 .072 5 1. ODD 

9876' GATE St andard q.31 .0618 0.9386 1.6 

12617 GMCC Standard 5. 65 . 0810 1.0116 1. 2 

12276 7.12 . 1021 0. 9703 3.0 

4361 5. 14 .0737 0.9835 1.7 

10154 4.03 . 0578 0.970 1 3. 0 

436q' q.75 . 0681 0.9888 1.1 

Q363' Q. 97 .07 12 0.986 7 1.3 

12502' 6.6Q . 0952 0.9895 1.0 

12159' 6.91 .0990 0.9792 2. 1 

12560' 6. 77 .0970 0. 9756 2.Q 

12562' 7.00 . 1003 0.9811 1. 9 

11538' 7.26 . 10Ql 0. 99 56 O.Q 

• GA TE Inst rument 
-..J 

.... 

Table 21. Boulder Laboratory Intercomparisons of Eppley Pyrheliometers ( NIP) With Quartz Window 

on September 1, 16 , and 26, 1976 

Instrument No . Calibration Constant 

-1 -1 (mV Ly min ) -1 - 2 (mV mW em ) 

ARL-NWS Sta ndard 1330 1. 915 .0274 

ARL-NWS Standard 50098 2.4 2 .0347 

GMCC Filter Wheel NIP Standard 13909 5.40 .0774 

GMCC Eppl ey Filter Wheel NIP 13910 5.76 .0825 

GMCC Eppley Filter Wheel NIP 13911 5.97 .0856 

GMCC Eppley Filter Wheel NIP 13912 5. 69 .0815 

GMCC Eppley Filter Wheel NIP 13913 5. 76 .0826 

GMCC Eppley Filter Wheel NIP 13914 5.78 . 0829 

MLO Eppley NIP (re tired) 3287 2.09 .0299 

MLO Eppley NIP (Temp. Comp .) 11372 5.22 . 0748 

GATE Eppley NIP (Stan dard ) 11755 5. 50 .0788 

GATE Eppley NIP 11946 5.62 . 0810 

GATE Eppley NIP 11947 5. 55 .0796 

GATE Eppley NIP 11948 4.80 .0688 

Ratio of Daily Totals: 

In st rume~compa ed 1330 Instrument 

1. 000 

1. 018 

0.9964 

0.9996 

1. 0056 

1. 0007 

1. 0037 

1. 0037 

1. 0114 

0. 9986 

0.9924 

0. 9998 

1. 0039 

1. 0029 

Deviation From 

Standard 

(%) 

1.8 

0. 4 

0.0 

0. 6 

0.1 

0.4 

0.4 

1.1 

0.1 

0.8 

0.0 

0.4 

0. 3 
'-J 

IV 

Idb lt-, 22 . Boulde r t..a !JO T'dlor-y i ntercompa risons of Eppl ey Pyrile liomete rs .... ith Fi l ter Wh ef.' ls 

]n ,tnlmFr"l t No ~: :":>c dt iOI1 

1390~J Iloulder (Standa rd) 

13') 10 Maurla Loa 

13911 Bou lder 

139 12 Sout h Po l e 

13913 Ha rr ow 

JJ914 Sdmoa 

Aq .:lif1 !:>t the S tandard on Octa ber 7-8 , ] 976 

ColI i b ra t ion CQn ~ldn t 

- 1 - I (mV Ly min ) (mV mW- tc m- 2 ) 

5 . 40 .0774 

5. 76 .0825 

5.9 7 .0856 

5 .69 . fJ 8 15 

5 .76 . 0826 

5.78 . 0829 

tiQ of Oai ly l~ls : 

In s t. rumf;' n t (Compa r ed 

13909/I n$ trume nt and (Oevi .;ltlcn 

.. n t h wi th \<1 1th 

QU.J T t l OCI Fi lte r' HG2 Filte r 

1. 000 

9~17( O 8%) .9923(0.8%) . 99 13(0.9%) 

. 9855( ! . 5%) . 99011 (1 .0%) .9949 ( 0. 5%) 

. 9985( 0. 2% ) 99B3( 0 .2%) 1.0022(0 2%) 

. 99J 4(0. 8% ) 993 3(0.7%) . 9885(1 . 1% ) 

9920 (0 .8:0:) .9957 (0.4%) . 98 71(1.3%) 

rrom St.;lndclT'd) 

wi t h 

RG8 F-i I lil;?J' 

1. 0174( 1. 7%) 

1. 0240(2 . 4%) 

1.0030( 0. 4%) 

1.029 (2.9% ) 

.9980( 0. n,) 

lab le 23 . Boul der l~b nt ry Intercomp ariSufl S of S tanda rd Py r-aOO'7lete r s a nd h~lf et e"l"s i n 1976 

PyranQmeter Com p~risons. O~C 6- 28 

In stl'u:T1ent No. 

AR L- ~W S Spect ro lab 73- 1 

GlfCC-Eppley Mo de l II 101"5 

GATE- Eppley Mo de l 11 9876 

Pyrhe li ometer Compa risons. S~p 1 , 16. 26 

Instrume nt No. 

A~l NWS l3 30 

GMCC £ppley Fil ter Wheel 

N1P 13909 

GATE Ep pl ey NIP 11755 

(mV 

(mV 

Collib" Jtion 

-I - 1 ly mi n ) 

5.7 2 

5.06 

4.31 

Ca l i brat 10 n 

ly - l em - 2) 

! .915 

5. 40 

5.50 

Co nstant 

-I -2 (mV mW em ) 

. 0820 

.0725 

.D618 

ConstAnt - 1 - 2 (mV mW em ) 

. 0274 

0774 

. 0 788 

Rat i o ( 1008 - 1400 MS1) , 

r ns trumen7" Compar ed 

7)- 1 I ns tr ument 

. 985 

.9779 

Rati o 01 Dai ly Totals: 

I nstrument/ Compa red 

1330/I nstrument 

1. 000 

0. 996'1 

0 .9924 

Deviation From 

Standa rd 

(%) 

1. 5 

2.2 

Devi ation From 

Standa rd 

(%) 

0.4 

0.8 
Changes in the ratios with so lar elevation between the pyranometers 

being intercompared are s hown in Figures 43-45. The global pyra nometers 

are more susceptible (between like instruments) to variances with so lar 

elevation. These variances are the result of differen t cosine respons es in the detectors at different sola r elevat ion ang les as well as 

to different instrument Zero s (recorded dark voltages) for like instruments. At low solar angles, irradiance signals ar e small, and small 

diffe rences in c osine response and instrumen t zeros can contri bute to 

large v aria nc es in mea sured irradiance between like instruments. A 

program to subtract out t h e instrume nt zero s from the measured irradianc es will be applied to the data and should less en the v ariance s ob -

served between instruments. 

Generally the pyrheliometers s howed a better agreement between 

instruments than the pyranometers did. There will be a r equ irement to 

continue intercOlnparisons yearly in orde r to continue tracing solar 

rad iation data in the GnCC program and to detect any cha nge in instrument sensitivity ove r the ye ars. 

" u 

" ~ 

, 

~: 

"' u 

., 

n 

., 

~ 

~ 

- - .. --1 

.;,.. .3 ~ 

I .,,, "" ::n 

r 

" 

" 

S·~ ", :~~~~~~ ·.: ~ .: :5~ 

:,0 -: .. ·t ~.'l'a 

1:: ~ Il:i 

\ '\ 

Figure 43. Two -minute averages of 

solar irradiance mea sured by the 

GMCC s tandard Eppley Nodel II 

pyranometer on a typical intercompa rison da y at Boulder Laboratory. 

73 

--, 

; I"" "I, 

:. 1: 1 

,I 

II~H~ IH:l 

(\.. . I.H: 

Fi gure 44. nvo-minute averages of 

the ra tios be tl,;leen the traveling 

standa rd Eppley Mode l II No . 12617 

pyranometer and the GMCC standard Eppl ey Model II pyranometer 

No. 10155 fo r a typical intercomparison day at CMCC Boulder Laboratory. 
-

" 

" 

J , 0 8 0 • 0 8 0 .. , ... : .' 

0 0 • , 0 , , 0 0 , 0 

0 0 0 

0 8 0 0 0 • 8 8 0 l ", . • 0 0 8 0 , , 0 0 0 

0 

0 , 

o 

0": 

o 0 0 

8888 o.ocoo Oil OO ij ~~ ::' LZ<- 0 0 

o, L-__________________________________ ~ 

'.0 r--------------------------- -----~ 

0 8 , , 0 , 0 0 • 0 8 oG G22 0 - 0 0 0 

0 

J 8 

0 8 8 0 0 0 0 0 

0 0 8 00;': 1 C 0 0 0 

00 0 0 0 

0 

8 8 8 8 0 0 0 ~ 0 

0 0 o 11GB. II 0 

0 0 - 0 0 

~ 0 J .. 

0 J ~ ... 11 2 1 ; " 

02 ------~------------------~ 

L , .. 

" j , ' "11 .2::: 

0 0 0 • 8 8 , 0 0 0 8 

0 0 0 0 0 0 , 

0 0 0 8 8 • 0 0 8 8 0 0 0 8 8 0 0 , , 

0 

0 , 0 0 0 8 0 8 0 

8 0 8 0 0 0 0 0 0 

.:,) . 3.l I"; 

0 0 0 0 

0 0 0 

GG22 0 

2 8 8 , ~, ~ 

8 8 8 ; 

':'~ 0 

, 

0 8 8 

, 0 0 

, 

• 8 , 

, 

I , 

, 

I 

o 

, 

I 

02 O'~ 06 ~8 10 ':! Iv 18 20 201 02 r .. 05 ~ 10 "2 ,~ \G 16 20 22 

I 

2.:l 

- u .. $u:, T . : ., . Svl.J' : ". 

Figure 47. Ratios of solar irradia nce me as ur e d through broad-band filters 

to total i rra diance (quartz) for s e lected cl ear days . The differe nce 

between ratios is the contri b ution of solar i rradiance b e tt4een the 

spec tral bands to the tot al solar irradia nce measured~ expressed a s 

a perce ntage. 

and the South Pole. Figure 49 p rese nts the his torical pl o t o f MLO 

normal inc iden c e transmissi o n values for clea r s ky co nditi ons . The 

transmission values are determined by the method o f Ellis and Pueschel 

(1971) where 

q In/In-1 

and q = average transmission f ac tor; 

I = 

n = 

solar irradiance 

secan t of zenith 

at normal incidences; 

angle where 2< n <5. 

Two sets of data are used in the plo t. Da ta prior to 1968 are from 

cl ear days s e lect e d by Ellis and Pueschel's criteri a . After 1968, data 

are from all clear days. The sudden d ec rease i n II q" J afte r s tra tospheri c aeros o l loading attributed to the Agung volcanic eruption, is 

76 
100 

~ 00 0 oOi 0 0 

o 0 0 0 

80 -

Sin10~ _ .. mJ ~r:l' 1977 

N 70 

" ~ ~ o 'b~ 0 0 

GO 0 o 0 0 0 

50 § O~O 0 0 o 0 0 0 

' 0 » O~O 0 o 0 0 0 

3D 0 7 09 11 1.3 1.5 I 7 

120 

110 r- ~0~8 0", 

8°~O 0 0 

0 0 

lOU fga f- .~1J"·1 l"~· ~nl.lolcl l 1977 N 

5 

~ 8() f- ~~8 0 

"' .. 0 0 

8° 0 0 0 

70 -

iIo*g 0" 0 

8.g <nO 0 Gn 

r-- ~g 0 0 

'" 0 

0 8 ~ rsro 0 

0 

5;)0 } ,:. 1., 1.3 15 1.7 

10n 000 

0 0 9", 0 

o '" 00 

()'1 111 F, . J(:." ;l:r . 1977 

80 - J 

" 0 00 

8"'<0 " 0 0 

70 - 0 

bO Co'll 0 €I~llD o 

'" 00~ 0 8!l~ O 

1.7 1.9 2.1 2.3 2.5 27 

A,r ·.1 ... \~ 

j 

0" Q 

-, 

eEl OGI 

cO RG2 

09 R~ 1 9 2 I 

-

0 0 -

OCI 0 

o qG~ 

o r·t,S 

1.9 2 I 

0 

:.J\.,;.1 

PG2 

%8 

2.9 3.1 

77 

Norma l incidence solar 

irradiances mea s ured tl1rough 

broa d-band fi l t ers, p lotted 

aga inst air mass . Air masses 

are correc t e d for s tation pres -

sure a nd are equa l to the cosecant 

of the solar elevation angle 

(P I 1013 mb) . s t a 
Mau na Loa 

As of the e nd of th is year , Mau na Loa Ob se rva tory has i t s own ful ly 

equippe d ch emist ry lab o ratory . The i n s t allation o f a n ion chromat ogra ph 

in December wi l l e llabl e the MLO sta f f to d o wide - ra nge chemical a nalys e s 

o n prec ip i tatio n samp l e s from this ob s e rvatory and fr om the Samoa, South 

Po le , a nd Barrow stations. 

By us e of a recently deve lope d t echni que tha t gre a t ly s imp lifi es 

the a naly s is of wa ter s amp l es, the ion c hroma tog ra ph is capa ble o f 

me asuring Ca , Na, K, NH 3 , Mg, F, N0 3 , S04, an d o t her possible ions at 

de tection limits o ne to two o r d e rs of magn i tud e lowe r than thos e obtained by wet che mistry techniques . Th e ins trume nt is ba sed on three 

prin cipl es : ion excha nge , e ffluent suppression, a nd condu ctome tri c 

de t ection . I ons can be separate d by their affinity for an io n e x c hange 

resin. Th e techn ique e volve d in the e arly 1940 's wh e n ion e x c hange 

r esin s bec ame comme rcially available, bu t was no t develop e d b ecaus e 

uni versa l det ec to r s b as e d on c ondu c tivity were hamper e d by ba ckground 

i nte rfe ren ce from the efflu ent mov ing phas e. Bre akthrough occur red with 

the t ec hnique ca lled e f fl ue nt suppression, whic h makes p ossib le r e moval 

of u nwanted ions fro m t he e ffluent s tre am by a second ion e xcha llge 

column. I n i on ch romatography , the el eme n t is r emoved or modifi e d to 

permit direc t d e tecti o n of sample io ns at extremely low background 

l eve l s. Cond uctivity ca n then be u sed as a me ans o f det e c tio n . 

The pH d ata t ake n o n the isl an d of Hawaii duri ng 1976 ar e S Wlll13-

ri z ed in F igure 5 1. Most not e wo rthy is the sepa r ation of the dat a by 

10r- ---r--.---r--'------.--- -'---r--.---~,,-- ; --'---r--'---r--.--- -' 

B 

( 

I ---- r. IO)IIl~d lo" (:;5-00 n l \ 

r",/ \ / -'\ I I \ 

."\ " 1 / ./" \ / \ 

- --KuIOlIl' '.'" ,I.e ' 2500 In\ 

- ---- Hlh)\6"n( 

------ KupahQ 1St: , L ... ·~t:fl 

--r' ;".---'\' \ ~-I / \ : \ ./' _. I ! \ \ \ 

.,..--------/<-+-==-""'--t---__! \ \ ;\ \ __ // ..... --.... \\ 

1/ I \ V \. '-- \ 

/ /, .... --_ .. .- \ 

" \ , . , 

, J; ~ 1 13 ~ 1 

1

3 

I! I I ~ '1 4;! '14 ~ II ~ j I : ~ II ~ \ ':' ~ I :" , J,~ 1 ',1 ~ I 1 Cj ~"l ~; : 115,~ 1 , :' :~ 11 ~ 1(~ i I' '~ i I 

J BO 3.90 <1 00 . 4 10 ·; .20 ,i 30 :.:l ~O 4 50 4 IJO .1 /(J 1 80 ; 00 r,oo 5 i :i '0 530 S. -HJ :'0 :;;. 110 

p H 

Figur e 51 . Histog r am of pH val ues in Hawai i. 

80 
e levation. Th e lowest pH values are at MLD> wh ereas the highest are at 

the sea level si t e , Kapoho. One co uld postulate tha t the sea sa lt 

aerosols have a n e utralizing effect o n the sea level r ai n fall a nd that 

in hig he r r e g io ns most of these aerosols are washed o ut . 

Also c ha racteristic of these data are the gen eral ly l ow values. 

For an a r ea far from either ma nmade o r natural polluti on s ources, the 

precipitation is more a ci di c than was expected. With th e new labo ratory 

faci lities at o ur di s p osal i n the coming year, ~~ e will investigate this 

pr ob lem extensively. HL O s taff chemist Al a n Yos hina ga visited several 

l abo ratories in 19 76 t o obse rve laboratory t echniques such as analy sis , 

washing proc edures, a nd s torage. From ]l is obse rvations, he h as esta blis hed standards of c l ea nliness and an aly sis that have reduc e d contaln inatio n t o a mi n i mum. 

Co nt roversy s till exists r ega rding the length of time between 

samples. Us u ally practice s ( i.e., mo nthly, weekly, daily, o r even t-byevent sampl i n gs) have vari ed dep e ndi n g on the resou rces a laboratory has 

to a nal y ze a given number of samples. The o reti cally, al l sampling 

practices s ho uld yield th e same results. However, a plot o f mo nthly and 

wee kly samp les (see Fig. 52) s hows that the values of the vleekly sampl es 

a v e raged over a mo nth a r e lower than the averaged values for the mo nth ly 

samples. Mor e tests wi ll be made to det e rmin e the c ause of this variation. 

52 . I I ~ __ j I I . I 

5 8 t5.~ 0 :----

-

- ~ G 

" , , -

3 8 

J. " 

-

. . 

, 

. 

. 

I . 

I 

----1 

. ~----

. . . . 

. " , , "" , 

8 1 

Figure 52 . ~l nthly pH values meas -

ured in Misco collector versus 

weekly pH averaged over the g ive n 

month. Weekly values a r e also 

plott ed (1976) . Monthly ph 1----) • 

weekl y a verage pH (----) , individual weekl y pH values 1 . ). 
Barrow 

Aft e r a testing p e riod of several wint e r s eason s , the open- c l o s e 

pr e cipitation c ollec tor (Misco) p r og ram wa s d isco ntinue d i n Barrow f o r 

two reasons: the coll ec tor effi c i e nc y was s e v e rely aff ec t e d by the 

extreme temp e r a ture and ic ing c o nditi o ns, and the amount o f yearly 

precipitati o n i n north ern Ala s ka ( 114 mm/yr) i s small. 

Th e local prog ram of s now coll ec t io n for pH mea surements was 

continue d during the wint e r sea son. From Octob er 19 75 to May 1976 , s n ow 

was co llec ted on a we ekly b asis at fou r si tes situate d north, east, 

south, a nd west of the observa tory. Sampl es were take n fr om n e wly 

fallen snow and fr om the o ld s now undernea th when po ssible. By s tandard 

pro cedures , the pH values wer e d e termined o n e i g ht samp le s. Tabl e 26 

s hows the v a lues for the 1976 wint e r season, and the c omb i ned values for 

19 75 and 19 76 which i n dic ate tha t s urface s now pH avera ges about 4 .85 . 

Und er norma l co nditions of carbo n d i oxide equ ilibrium, values of snow pH 

s ho uld range from 5.2 to 5 . 7 . We mu st conclud e that eithe r local o r 

r egi onal acid ic materials a re being sc avenged by the snow. Plans ar e 

be ing made to evaluate this phenomen o n further by us ing the ion chromatogr ap h. 

Samoa 

Tabl e 26. pH Values of Snow at Barrow from October 1975 to May 1976 

Aver age 

New Snow 

Ol d Snow 

Total 

1975 + 1976 

North 

4. 73 

4.86 

4. 79 

4 .84 

South 

4.94 

4 . 91 

4 .92 

4. 80 

Ea st 

4 . 67 

4 .88 

4.76 

4.87 

West 

4. 78 

4. 90 

4.83 

4.92 

Becau se of the e x treme diffi c nlties in s h i pping c he mi c al suppl ie s 

t o Samoa, on l y a prelimi nary progr am of pH me as urements co uld be es tabl is he d during 197 6 . Co lle c tions wer e made from April through July, t h e 

aver a g e pH value being a b o ut 5.0 for 27 s epara te de terminations. By the 

end o f the y ear, the supply p r oblem had been so l ved (some orde rs took 

more than a year ) , and a c ompre hensive pH and condu c tivity pro gram was 

5ta rt e d. 

In tlarch, the EPA L')lle c t or was remove d from t h e NWS offi ce near 

the Pago Pago Interna tional Airport, refurbis hed, and placed on the roof 

o f the Samoa Observatory building (Fig. 5 3) . Data f rom this colle c tor 

have been p u blished i n Atmospheri c Turbidity and Prec ipit a tion Ch emistry Data for the World . 

82 
Fi gure 5]. l1isco collector mounted 

on roof of Samoa Obs e rvatory. 

4.6.2 Regional Precipitation Chemistry 

The programs at the ten WHO regional s i tes have continued under 

joint NOAA-EPA sponsorship. Monthly samples are sent from the collection sites t o the Environmental Monitoring and Support Laboratories of 

EPA in Resear c h Triangle Park, North Carolina. These data are published 

annually in Atmospheric Turbidity and Precipitation Chemistry Data for the 

World. For further details on thi s network see Miller and Highsmith (1977). 

4.6.3 Special Study 

The Washington, D. C,} volunteer program, begun in 1974 to establish typical pH values i n an eastern urban area, ha s co ntinued. Figure 

54 shows that the median value for the D.C. network i s 4.0} whereas the 

median value for the island of Hawaii is 4.8, A report on the data 

taken thro ugh 1975 is presented by Miller et al. (1976). 

4.6 . 4 Program Plans 

Plans for the precipitation program within GMCC are as foll ows : 

(1) With the Mauna Loa laborato ry fully equipped, samples will be s ent 

on a regular ba s is f rom the Barrow and Samoa observatories for full 

chemical analysis using the i on h~omatograph. (2) A special study of 

precipitation c hemistry on the island of Hawaii will begin at the end of 

1977, Besides analysis of precipitation sample s , c oncUrrent c loud water 

analysis , aerosol c hemistry, and other parameters will be measured. 

(3) A s tudy o f s now c ollection and analysis will be undertaken at the 

Barrow obs e rvatory for the 1977 winter sea s on . 

83 
40 

30 

" ~r---

U I--

'0 20 • E 

o 

z 

-

-

I 

r-- .--

= -

o f-------, r-- I r----r---l-

\

321 13.31 13.->1 13.51 13.61 13.7113.81 13',9114.0114,11 \4.21 1',31 1

4

.

41 14

.51 \ 4.61 \ 4.71 \ 4.

81 1'91 \5.0 1 

1

5

, 11 I 10 10 to to t o 10 to 10 to t o to to \0 to to to to I D toO to 

3.30 3.40 3.50 3.60 , 3.70 3.80 3,90 400 4 10 \ 20 11,30 4 40 450 11 60 4,70 ": .80 <:1 90 5.00 :, to 5.20 

p H Intl.'rVi l 

Figure 5 4. Histogram of pH values in Nas h ingt on, D.C . f 1976 . 

5.- COOPERATIVE PROGRAH 

Du ri ng 1976 , GMC C co nd uct e d a st udy o f the nl arine aero so l in coopera tion with th e Canadian Government. This projec t was requ ested by 

Will iam Elliot of ARL, and all data were f orwarded to him. 

We installed a Gardner coun ter on the Can adia n Wea ther-ship Pap a and 

f our ro uti n e ob servati o n s pe r d a y were perfo rmed by the meteorologi cal 

crew fo r the e ntire year. Most previous ocea n ic ae ro sol studi es had 

be en Jna de from mov ing shi ps. Conse n s u s was tha t a I-yea r s tudy from 

Pap a wo uld give us eful dat a o n po s s i ble annua l trends in aerosol c oncentration at a statio nary o c ea n site. At the end o f 19 76 , all equipment was retu rned to GMC C and the study was terminated. Dr. Ellio t is 

c urrentl y stu dying the data in detail; a preliminary examinati on indi -

ca tes that they are of high qu a lity. 

We had und erstood that the Canadi a n s were co ns idering es tablis h ing 

Papa as a baselin e geop hysica l mo nitoring site (and tha t aerosol pa rticle observati ons mi g ht continue after our study). Howeve r, th i s apparently has not be en do ne. 

The Papa dat a \4 e used i n o u r s tudy \.; ere the me teorolog i cal a nd wave 

hei ght data. Howev er, it is c onc eivable that tile o the r o ce ano graph i c 

data co uld b e i mp ort ant in co ntinu ed s tndy of aeroso ls. We ha ve no 

def ini te plans fo r subsequ ent ae r osol s tudies ; howeve r, it would be 

desirable to repea t suc h work a t least eve ry 5 years and t o e xpand the 

prog ram to inc lude o ther a erosol pa ramete r s s u c h as si ze d istributi o n 

and ch emistry. In genera l, Papa should be cons idered a valua ble measurement platfo rm since it is t he o nl y oce an station e ntirely fre e of 

co n tinental or i s la nd effec ts . 

8 4 
6. DATA flANAGENENT 

This sec tion documents changes in the hardware and softwar e configurations u sed to reco rd and pro cess dat a from the princ i pal mo nitoring sys tems in ONCe. A ca tal og of the data pub lishe d durin g the yea r is 

also include d. 

6.1 Data Acquisition 

6.1 . 1 Ha r dware Considerations 

In Janua ry 1976, the ICDAS was i n s tal led at th e new observatory on 

Cape Matatula. The startup of this central rec ording system went very 

we ll, and data re co rding be gan on the 15th of th e month. With the 

exc e ption of an uninterruptable power supply, thi s installa tion is 

identi ca l to those at the othe r thr ee observatori es. Noise tests ru n at 

th e time of installation yielded very good r es ults, partly bec aus e o f 

the e xcelle nt ea rt h ground available. 

Voltage offs et e rrors, r es ulting from e xcessive nois e pickup in the 

ICDAS, e a continuing prob l em at HLO and Barrow. To isolate the 

signa l return and thus to break ground loops, isolation amplifiers we re 

prep ared for all signal line s entering the ICDAS. Although thi s proce dure decrea se d the noise l eve l on s pecifi c channe l s , it did little to 

reduce th e pickup of h igh fr eque ncy noise fr om the mi nicomputer in the 

I CDAS . Te s ts will continue. 

During January, two separate events ca u s ed extensive data l oss es at 

t he observatories in th e North ern Hemisp here. In August 19 75, a seve re 

power transient t oo k out part of the ICDAS at Barrow. At Mauna Loa, a 

lightning strike in Decemb e r caused extensive damage t o the mu ltip lexerdigitizer and minicomputer in the I CDAS. Both eve nts caus ed inte rmitt e nt failures that resulted in loss o f data r eco rdin g ca pab i lity during 

the first months of the year. Eventually, the fa ulty equipme nt had to 

be repla ced. 

6 .1.2 So ftwar e tlo difi ca tions 

As new s tations were activate d a new e dition o f the executive 

so ftwar e (BOSS) was issued. The struc ture of the r e corde d data did not 

c hange, but mu c h of t he co nt ent o f the co de did . This complicated 

software maintenan ce, and the d isc repanc y, al o ng with some opera tional 

difficulti es, made it nec essa ry t o produ ce a ne~ , s tand ardized BOSS for 

al l stations. BOSS 7 6186 wa S iss ued in the fal l. It include d an upd a ted v e rsion of BASIC wi th stringed " if 11 st atements a nd AN SI Standard 

Cod e II input-output capability, two features us e ful i n BOSS. A new 

CALL s ubrout i ne wa s ad ded that writ e s the co re-image r ecords onto tap e. 

In this way a co py of the op erating system ca n be made ea c h time the 

data tapes are c hanged . BOSS 76186 contains data re co rds of fixed s ize 

an d a subro utine to cont ro l the week ly CO 2 calibration. Th e time 

85 
Figure 55. Data reduction facility. 

required to print the daily log was reduced by a factor of five and the 

method used to place comments on the data tapes was streamlined. 

Although the codes are not identical at each station, the discrepancies 

are limited to a few modules. The software is not complete by any 

means, but future changes will not affect the structure of the data 

arrays or the operation. 

6.2 Data Reduction 

The tapes from the observatories, containing the data for a lO-day 

period, are checked for quality immediately upon receipt. The data 

reduction facility is used for this purpose (see Fig. 55). A report is 

prepared on each tape delineating periods of missing data and excessive 

system noise. The calibration facto~s sto~ed in the data ar~ay are also 

checked. Following this initial checkout, the calib~ation records for 

each senso~ are tested for accu~acy. To inc~ease the flexibility of 

this facility a high-speed paper tape reader and punch, and a high-speed 

printer were added to the system. A second tape drive will be added 

soon. 

During the year, a set of programs was written to print and graph 

data from the stations ' data tapes. In particula~J a ~outine was written to compute the hourly integral values of solar radiation and to plot 

the data from the five pyranometers and the pyrheliometers, in I-minute 

increments. 

86 
6.3 Processing 

Proc e s sing is the i ntermediate step where the data are prepared fo r 

special publications and archiving. This data manipulation is performed 

on the computer in ERL. The data have been assembled on tape in I-mo nth 

blocks. 

6.4 Archiving 

Extensive discussions with individuals r esponsible for data exchange at the National Center for Atmospheric Research and National 

Climatic Cente r, produced gu i delines for a r chiving GMCC data. For 

example, it was suggested that data from d is crete mon i toring programs 

not be mixed with data from continuou s programs (Jenne a nd Josephy, 

1974). Also, for e ase of access the co ntinuous data s hould be in an 

integer format like the surface we ath e r observations of NWS. The s truc -

ture and format dis played in Tabl e 27 will be us e d for the continuou s 

data. No preambl e or identifie r r ecords will b e inc luded so th a t a 

number of tapes ca n be combined without any discontinuities. The disc ontinuous data from monitor i ng programs will be grouped into files. 

Each file will c ontain a preamble record to d e f i ne the data se t written 

in the plain l a nguage format, Fortran itA" . 

For b o th sets of data the medium will be the same: computercompatibl e magnetic tape re c orded on n i n e tracks, at a dens ity of 1600 

bytes per inch (phas e - e ncoded). For maximlUTI exchange , the EBCDIC 

(Extended Binary-Coded Decimal Interchange Code) int e rnal character code 

will be used. 

The record s containing conti nuous measur ements will begin with the 

c haracter count preceded by 99 . The station number, date, and time of 

the observation f ollow, completing the identific ation block. The measurements are grouped into f o ur s ections: a e ro s ol populatio n, gas concentrations , weather measur ements, and s olar radiation . Th es e parameters (T.6.4A~ constitute th e primary me a s ur ements. The secondary or 

calibration me asurements wi ll be appe nded to the record as they are 

availabl e . 

87 
Table 27, Structure of Data on the Archive Tapes of Continuous Observ ation 

-

Chara cter 

Count 

9 9 X X X X 

Data Field 

Condensation 

Nuclei 

, 

o 

o 

I 

2 0 X X X X X X :, 

Data Field 

Horizontal 

Incidence 

6 0 X X X X X X 

Tape Field 

Number 

001 

002 

003 

004 

005 

006 

007 

008 

009 

010 

011 

012 

013 

014 

015 

016 

017 

018 

01 9 

Tally 

X X 

Tally 

X X 

Stat ion No . 

o I X X X X X 

Data Field 

'" '" '" 

Integrated Aerosol 

'" o 

'" 

~ 

'" 

Scattering 

2 4 X X X X X X 

Data Field 

Oxidant 

4 4 X X X X X X 

Tape 

Pos ition 

001 006 

00 7 013 

014 021 

022 027 

028 037 

038 047 

048 057 

058 067 

068 077 

078 087 

088 097 

098 107 

108 117 

118 127 

128 137 

138 147 

148 157 

158 167 

168 177 

88 

YR 

I 0 

Ta Ily 

X X 

Ta II y 

X X 

" i 

Date Hour 

MO DY ( Cut) 

X X X X X X I I X X X X 

M 

'" o ;; Field o No . 

Data Field 

Integrated Aerosol 

Scatte r ing I Tally 

~ 

o 

o 

2 5 X X X X X X 

Data Field 

Ground 

I X X 

~ 

'" '" 

Temperature I Ta lly 

5 7 X X X X X X I X X 

DO ~ 

'" '" 

Element 

Chara cter Count 

Station Number 

Year - Mo • Day 

Hour - Min 

Condensation Nuc lei 

Integrated Aero sol Scatt. 1 

Integrated Aerosol Scatt. 2 

Integrated Aeroso l Scatt. 3 

Integrated Aerosol Scatt. 4 

Carbon Dioxide 

Ozone (Surface) 

Wi nd Direc tion 

Wind Speed 

Stat i on Pressure 

Air Temperature 

Dew-Point Temperature 

Horizontal Incidence Irradiance 

Ox idant (Surface) 

Ground Temperature 

26 

R 

M 
7. RESEARCH PUBLICAT I ONS 

DeLuisi, John J., P. M. Furukawa, D. A. Gi ll ette, B. G. Sc hu ster, R. J. 

Charl son, W. ~J. Porch, R. W. Fe gley , B. M. Herman, R. A. Rab inoff, 

J. T. T"'itty , J. A. Weinman (1976): Results of a comprehen sive 

atmospheric ae rosol-rad iation exper imen t in th e so uthwestern United 

States. Part I: Size dist ribut io n, extinc tion op ti cal depth and 

ve rti cal profile s of aeros ols susp ende d i n the atmosphere ; Part 

II: Radiation f lux meas urements and theoretical interpre ta tion. 

,1:. Appl. Meteorol. 15:44 1-454; 455-463. 

DeLu isi, J. J. , R. K. Sato a nd D. A. Gillette (1976) : On the se nsivity 

of errors in c alculated Mie optica l cross sec tions due to errors in 

samplings of Junge-type aeroso l size distributi o ns. At mas. Env. J 

10:717-721. 

Duce, R. D., J. M. Mil ler, and J. L. Heffter (1976): Tra ce metals in 

the marine atmosphere: sources and fluxes. In Mar ine Pollutan t 

Transfer, D. C. Heath and Co., Lexington, Mas s., 77 -1 21. 

Hanson, K. J. ( 19 76): A n ew e stimate of 

sur f ace on zon a l and globa l scale s. 

4443. 

solar ir radia nce at the Eart h' s 

J. Geophys. Res., 8 1: 44 35-

Hoyt, D. V. ( 1976): The radiation a nd e nergy budgets of the Earth using 

both g round - based and satellite-derived values of tota l c loud 

cover. NOAA Tech. Rept. ERL-36 2-ARL- 4, 124 pp. 

Komhyr, W. D., a nd T. B. Harris ( 1976); Mea sureme nts of atmosphe ric CO 2 

at the GMCC baseline stations, paper presented at a Techni ca l 

Confere nce on Atmosphe ric Pollution Me asurement Techniques hel d in 

Got henbu rg, Sweden , October 11-1 5, 197 6. To be pub lis hed by Wl10. 

Komhyr , W. D., and T. M. Thompson (1976): Fluorocarbon-I1 meas ur ements 

at th e U.S. GMCC Boulder stations, pap er presented at a Techn ica l 

Conferenc e on Atmosphe ric Polluti on Meas ureme nt Techniques held in 

Gothe nburg, Sweden, October 11-15, 1976. To be publis hed by wt!O. 

London, J ., R. D. Boj hn ov, S. Oltmans, and J. 1. Ke lley (19 76): At la s 

of the gl obal distribution of tot al ozone, J ul y 1957-June 1967. 

NCAR Te c h . Note 11 3. 

ae nd onca, B. G. (1976): ~!easur rnent s to 

ties o f atmosp heric aero sols. NOAA 

evaluate the be nchmark proper -

Tech. Re pt . ERL 35 5 - ARL 3. 

Mil ler , J. a ., G. F. Co tton , D. H . Pack, J. a. Mit chell, a nd M. E. Smit h 

(1976): An evalua tion of precipita t ion pH data f rom the Washingt on, D.C. , area co llecto rs du ring 1975 . NOAA Tech. Memo. ERL-ARL57. 

Oltmans, S. J. , a nd W. D. Komhyr (1976a) : Su rf ace o zone in Antarctica, 

NOAA Tec h . f'l e mo. ERL ARL-56 , Air Resource s Labo ra tory , Boulde r, 

Colo. 

Ol tmans, S. J. , and W. D. Komhyr ( 1976b): Su rface ozone i n Antarc ti ca. 

J. Geophts . Res. 81 : 5359-5364. 

89 
8. REFERENCES 

Atmospher1C turbIdIty and preCipitation chem ist ry data for the world 

(Annual): Environmental Data Service, Asheville , N.C. 

Bodhaine, B. A. ( 1977): Nucl ei monitoring at baseline sites: Barrow, 

Alaska; Hauna Loa, Hawaii; American Samoa; and South Pole . Report 

prepared for the Ninth International Conference on Atmospheric 

Aerosols, Condensa tion, and Ice Nucl ei , September 21 -27, 19 77, 

Galway, Ireland. 

Crutzen, P. J. (1 9 74): Photochemical reactions initiated by and influencing ozone in unpolluted tropospheric air . Tellus, 26:47-57. 

Ellis, H. T., and Pueschel, R. F. ( 1971): Solar radiation: absence of 

air pollution trends at Mauna Lo a . Science, 172:845-846. 

Fegley, R. W. , and H. T. Ellis (1975a): Lidar 

spheric dus t cloud layer in the tropic s . 

~(4): 139. 

observations of a strato -

Geophy s . Res. Lette r s, 

Fegley, R. W., and H. T. Ellis ( 1975b): Optica l effects o f the 1974 

stratosphe ric dust cloud. ~.~., l.!<.(8):1751. 

J e nne, R. L., and D. H. Josephy (1974): Techniques for the processing, 

storage and exchange of data. NCAR Tech. Memo., NCAR-TN/IA-93. 

Mill er , J. M., G. F. Cotton, D. H. Pack, J. M. Mitchell, and M. E. Smith 

(1976 ) : An evaluation of precipi tation pH data from the Washington 

D.C. are a collector during 1975. NOAA Tech. Memo., ERL ARL-57. 

tliller, J. tl., and R. Highsmith (1977): The WMO regional preCipitation 

chemistry network in the United States. NOAA Tech. Memo., ERL ARL60. 

Miller, J. M., and J. Wisniewski (1977): A survey of precipitation 

chemistry s tudies--North American and adjacent areas (unpublished 

ms. ) . 

Ozone data for the world, World Ozone' Data Center, Atmospheric Environment Service, Downsview, Ontario, Canada, M3H 5T4. 

Ro s en, J. tl., D. J . Hofmann, and J. Laby (1975): Stra tospheric aero s ol 

mea surements I I: The \-Jor Idwide dis tribution. ~. Atmas. Sci., 

32 (7): 1457-1462 . 

Russell, P. B., and R. D. Hake, Jr. (1977): The post-Fue go stratosphere 

a erosol: lidar measurements, with radiative and thermal implications. J. Atmos. Sci., 34(1): 163. 

Suomi, V. (1977): The need for cl imate monitoring. Energy and Climate, 

National Aca demy of Sci ences , 128-132. 

Watkins, J. A., Editor (1976): Geophysical monito ring for climatic 

change, No.4 , Sunmlary Report 1975. U. S. Department of Commerce, 

Boulder, Colo., 131 p . 

90 
9. GEOPHYSICAL MONITORING STAFF 

Director's Of fice 

*Kirby J . Hanson , Director 

*Barry A . Bodhaine, Research Physi c ist 

-kCera ld F. Cotton, Statistician 

Helen C. Cook, Secretary 

Richard Cram, MeteoroLogist 

.... J o ho DeLui s i, Meteorologist 

*Ronald Feg l ey , Rese arch Physicist 

"--Be rnard Mendonca, Resear.ch Meteorologist 

James A. Wat kins, Exe c utive Assis tant 

Techniques and Standards Group 

* Walter D. Komhyr, Chief 

*Robert Grass, Physi c i st 

* Thoma s B. Harrls, Meteorological Tec hni c i a n 

Dougla s V. Hoyt, Physicist 

Consta nce Mapes , Secretary 

*Sam Oltmans, Physicist 

)~ Thayne Thompson I Pbysicis t 

AcquisitiOn and Data Management Gronp 

*Gary A. Herbe rt . Chi ef 

Arija Bottomley. Cl e rk 

Joyce Harris, Comput e r Programmer 

Milton S. John son , El ec tro ni c Techni ci an 

Analysis and Interpre tation Gr o up 

Charle s P . Turner, Research Mete orologist 

Mauna Loa Observatory 

*J o hn M. Mill e r, Director 

J ohn f . S. Chin, Physicist 

Howard Ellis, Pbysicist 

Judith B. Perera, Secretary 

Mamo ru Shibata, Electronlc Techn ician 

Alan M. Yoshinaga, Analyti cal Chem i st 

Ba rrow 

'';-Erner50 n G. Wood, Lt . NOAA, S tati o n Chief 

Ro ger Williams, Electronic Tec hni cian 

South Pole 

* Val e ntill e Szwarc , Me t eo rologist 

James Jordan, El ec tro ni c Engineer 

Samoa 

*Donald W. Nelson , S tatio n Chi ef 

Larry Westerma n, Physical Scientist 

*Contributors to the Summary Re port 

91 
APPENDIX A 

Workshop Revi ew 

In February t he GHCC prog ram he ld at Bould e r a wor k shop conc erned 

wit h an assessment of current pro gre ss in radiation and aero so l measuremen ts and thei r appl ica tions to probl ems i n atmospheric science. A 

tota l o f 41 spe cialists from universities , government agencie s , and 

private industry att ended the workshop and provided va luable information 

for the dir ection of fut ure res earch . This review of the del iberations 

of the workshop was made available for dis tribution. 

92 
HORKS HO P RE'I IEl-I 

l.Jo l-l i ng r, ,"OUP on Geophy sic a l Pon itor i ng for C imat ic Change {GI':CC) 

Radiation and Aeroso l Mea ur~nen s and thei r Pppl ications. 

Boul der, Ca l ol-odo, February 4- 5, 1976 

~ohf1 J . DeLu is ; 

I'i rb'l J. Hans on 

~! atio r;J1 Oceani c and t tmos rher ic A{Jrlli-li stl'ation 

Ai r Re sol}l-ces Labo ratory 

Bo.llde r, Cola l"ado H0302 

9 3 
1. In t r oduc ti on a nd bac kg r ouno 

Tne Ge ophysical I·',onitor ing for Cl irnat i c Change (G;'!CC ) Prog r a". of 

the il ationa l Oce:1 1l 1c a nd Atno s phel-1c Adillioi str t'!tion \-Jas or gan iz ed to 

provide a part o f the t r.ited Sta tes' cont ribu t ion to the i rlte rnat ional 

need fm" a Det tel~ und erstandi ng of the gl obal e nvirOIYTl ent. 

he 0 j ectives of th e [,1-iCC Pl"og r" am are: 

To non ; tor trace almo Srhe(~ c gases and aeto501 ca nst; t uents 

fo r base l ine va l e detern' ina l i on ; 

To de te r'mi ne r a t es of c hMlqe of these r. sph er ic co nsti tu e nts 

and to examine so urces, si nk s, an budge ts; 

To de ter'1n i ne po ss ible e ffects on c limate of t hese rates of 

c hang e in c ol l abo r at ion with mode l ers and oiag nos Ci c i a ns _ 

Accomp lis hme nt o f the se ob.i ec ti ves on a gl o ba l basis requ i l"eS conti nuous 

observa tions at " clea n a ir" 1 ca ti on s in para ll el willl pr ec i s ion observi ng tec hniq ues and r igl d Qll al i t : .... con trol, a ll for an extended peri od of 

a t least severa l dec ade s. Th e G!·lce p,'og r a," ha s f our fJl1y o pe l'a ti o". 1 

baseli ne obsel"v a t o(i es : r"1au na too3 , qd\-Id li ; Barrol'i, P.,laska; Cape f'-l a tatu l a , 

Amefic an Sall1oa ; a n(1 Sout h Pol e , Anta r ctica . Ba s i c r esearch and devel -

opme nt act iviti es in cludi rHJ Gf: <J e loprnent o f measur eme nt teChnol ogy ~e 

bei ng co nd ucted at some o f these statio ns and at the Boulde r, Calo l"ad o, 

he adquarte r s , 

Pr og ress in t he at mo oner c sciences often in.' <es a"~es in obser vational r eoui r ements, tec hniGue s . and specificat :olls . COG sE ~~ y, 

co nt inua l asse ssnent of such Cht1nges i s vi t a l to t he establ r~e nt of 

priorities for Gt-'CC in ol"der t o (1 r ope l'ly su pp l ement t he need s of t he 

sc i ent if i c cQllifllunity _ I n v ie l'/ o f t he f orwa rd pl"og ress that has bee n 

na de i n ae'"os a l l"eSea rC r elateo t o ll(l ~e vd)" ia i ons i t app ear ed 

tinle l y to conve ne a WO l" ~ i ng gl'our of pecia l~ sts for a cu rr ent assess -

ment o f e xper in ent a l dtlt a fieeds , I-li t h pa ftl cu lar co ncer n f OI ' 1'l() e ll ng 

o f clil"ate, 

94 
2. SynopS iS of Works hop Activities 

A workshop wa s conducted on 4- 5 February 1976 at Boulde r , Co lo. on 

the s ubjec t of ae rosols in connection with c lima te variations , The \'lOr kshop program was li berally structured in orde r to allow the participants 

to express opinions on other physi cal quantities th a t GMCC was already 

monitoring or might consi der for monitoring in the future. The participan ts are ]j s ted in Append i x I. 

Th e schedule of acti vitie s wa s divided into two par ts. 

Part I , consisted of bri ef presen t a ti ons of GMCC's pre sen t 

scientific act ivities by its personnel and exte rnal collaborators. 

Part II consisted of three open discussion sessions on the 

fa 11 o"i ng prj nc i pa 1 top i cs: effec ts of aeroso 15 on the genera 1 cj rcu -

la ti on and clima te, ground truth data for satellite research programs, 

and sol ar irradi ance research. 

Because material pres ented in the first part is des cr i bed in GMCC's 

annual reports, (see references) technical reports, and formal publicati ons, it need not be inc luded in this review. Thi s rev iew \,/i1 1 cover 

onl y th e second pa r t of the working group's acti vities. 

3. Activities in Part II 

Section 1: Effect of Aerosols on General Circu l a tion and Climate 

A methodology, suggested by Junge (1975) wa s presented. It cons is ts of a series of research efforts aimed at un derstand ing the influence of aerosol s on the genera l circulation and climate. Three basic 

steps are involved, as ind icated in Fig. 1. The first step is to understand the non-uniform qua si-steady state dis tributi on of aerosols in the 

troposph ere on a global scale, and t heir changes as a fun c ti on of production , mod ifi ca tion and removal processes. The second step deal s "ith 

und erstanding t he optical properti es of aerosol s so that both direct and 

indirect effects on the s hort and long-\·,ave radiatio n budget and the 

indirect effect of aeroso l s on clouds ca n be de termined. The final st ep 

requ i res an underst anding of the direc t and indirec t effect of aerosols 

on t hree dimensional circu l a tion and climate, inc luding all feedback 

processes by proper inc l us i on of aeroso ls in atmospheric simu lation 

mod els. 

95 
Extens i ve di sc uss ions follQl-,'ed on the f e asibility of carry ing out 

this ambitious research e ffort, and on the phi los ophy of t hi s propos ed 

methodo logy . It via s po in ted ou t t hat a li mi tation of t hi s me thod is 

hat the I)roposed radiation ca l cula tions in genera l circu latio n n'ode l s 

vlou ld de pend on the a ssump tions inherent i n /-' ;e theory (such as sp herical parti cles) _ To the extent these as sump t ions are invalid repre -

se ntations of the real at;,osph e ri c aeroso l . the resu lting radiation flu >: 

calcu lati ons "il1 also be inval id . It \'Ias concluded tha t a lt hough good 

progress has been made in t he chemistry of atmosph eric aeroso ls. much 

nOI e must be kn OI-m about aeroso l pr oce sses before t he second ste ~n 

Junge's a pproach cou l d be reached. It i s not likel y that a suffic ient 

understanding of aeroso l ;:--' ocess es requir ed in s tep tl'IO 1-,'i11 be aChieved 

III t he near f uture. In additio n , step one is a fo rmida ble t ask whi ch no 

si ng le na ti on c oul d achi e e by itse l f (I·lithou t a massive cOllm i tme nt of 

resources) i f the parameterizat i on of ae rosols, gl oba ll y. as a function 

of sou r ces, mod ifi ca tion , and r eMo va l is the fin a l goa l. 

I t wa s con cu rred, genera ll y, that we s hou l d l ook for alter nate ap -

proac hes that ',JQuld offer the poss ibil i ty of imr:ediate ap p l i ca t i o n to 

modelers needs and woul d not r equire the mass i ve ef &ort whi c h appears to 

be requ il'ed if J unge ' s a pIJ ro ac 1 I'/ere adop ted. 

One a1 te )'n ate app roach \-Ias di scussed ',jhereby ae l' oso1 opti ca l P"o -

perties are o bta i ned directly from radiat io n observat ions rathe r tha.n 

t nmugh a knQlde dge of their cherll ca l compo s ition (f i g .I ). In this "ay , 

tl-IO fH.l' l'pOSes are se(ved: 1) [n itli1l ba sic i llf nna t i on on aerosol 

op tic al prope lAt ies Hil l become avai i a ble al mos inned l ately fOl~ mode lins 

needs; an d 2) t he ra aiati on measureme nts of opt ica l pr op erties Cdn be 

used as an ul t ima e va lido i on o f t he !!lo re f una an1erlt a l cal culations of 

opt 1 Cd 1 v1-ope rt i es (ttlro tlgh t eory) ba sed On cil cmi ca 1 mea suren1eo ts of 

~ e aeroso ls . I n order to appl y [ he aerosol op t ic al roperties to 

c ;l"cu l ati ol1 ll1odel s, S le sta tistics on thei r" vCJ' i aoilitj as a func tion 

of <]e ogt~a phi :)l a)~ea fldst be al/~i1 able . 
a . Aeroso 1 Hode l s 

[3 ecau se o f the high l y varia ble Chcl lical compos l ti on an d phy s ica l 

properties (suc h a s shape and si ze di st ribut ion) of aer oso ls, th ere 

1,',d S some doubt ex pre ssed as t o ~' het he r a typical or ave rage aeroso l 

cou ld act uall y be ide f:L~~i ed. It wa s conc l ud ed that exist i ng ~now

ledg e of ael~o ol ,J r' o;)er ties is in s uff i c i ent to an S\'/er the ques tlon at 

pt'esent . 

It was sta ted that r eg ional aeros ol characteris t i cs reflect th e 

l oc al source cllaracteristic s (natura l and anthrcpogenic) and sub sequent 

time- dependent t ran s fo rma tions t ha t occ ur. Oi ff usion by :L.rbulent 

nl ixing ant advection di c tat e the bounds (or doma in) of the as socia ted 

aerosol . A mode l \'/a5 des cri bed in \'Jhic h the grOS5 nat iona l produ c ts o f 

geograplli c r eg ions detel1t1 i ned t he relati ve abund ance of ae r os ol sources. 

~~e mea n circu l a t ion patterns and aeroso l residence ti me s determined t he 

a pproxima te geogra oh ic bounddr i es of ael s generated in highly industria li zed l oc a tions suc h a s these fou nd i n Europe and the United 

Sta te s . 

b. Background aeroso l s a rld ex pedit ionary measurene nts 

The existenc e of a typi ca l backg rou nd aeros ol in the midd le and 

~l Je !' tro po s phe re Has debat.ed . Such a background aeroso l ca n only be 

pos tu lated s ince th ere is bu t l i mi t ed i nforl'la ti o n on t he c hemi s tl"y and 

size stribut;o n pl"ooe rtles o f aerosols in the upper a l titudes" Ther e 

I"las a strong rec ontnendatio n to ex pan d the fr equency, geograph ical range 

and sc i e nt ; f ie s cope of ex ped i ti onary (s hor t-te r m) measurements in order 

to gain bas ic and preli mi na ry understandi ng o f th e chem ical .and phy s ica l 

p,"c )De rti es of aeroso ls i n the hjgh troposphere" Thi s wou l d ass ist in 

pl-ovi ;n9 d irec ti n fO "( def in i ng necessary long-term mo nitori ng on a 

global s ca l e for appl ica t ion to c li nat ic modeli ng . An ex ampl e of an 

ex ~ed ti onary aeroso l res eal-e h pro gram of t hi s type is the Sovi et Uni on' s 

(AEIIEr (COMp lex Atmosp he ri c Energe t ics Exper i" ent , I:ond ratyev, 1973). 

97 
c. Cl oud nu c l ea tion and nlodifica tion 

A eco~ ndation was made for improvi ng the quality of physical and 

radiat ive measurements o f c louds, such as c irrus, c umulu s and contrails. 

Po ssi ble anomalies in ra di a ti ve absorp tion rtie s due to Il atural and 

po llutant aerosol s He re co de )~ ed . 

Al so recomme nd ed \·, as inc r ea sed inves tigative effort ,~ med at the 

effec t of aeroso l s in modify ing c l oud pro perties (dro pl et s i ze and 

conc entrati on) whi c h in t ur n, a l ter the radiative propert ies of t he 

c loud s . Cl oud co nd ens ation nuc l e i mea sureme nts \·,e r e sa id to be vita ll y 

impo r ta nt beca use of their ability to co nt.-ol c loud de ve l opme nt. The 

importa nce o f measurement speci fic i ty suc h a s s i ze di stribution and 

c hemica l compos iti on was str essed . 

d. Aerosol op ti ca l p roperti es 

The aeroso l opt i cal properti es needed for c1 imate model ing \·,ere 

s ta ted as: 

(1) op t i ca l dep : " 

(2 ) a l bedo of s ing l e sca tter ing 

(3 ) pha se function 

( 4 ) a bso rption to ba ckscatter 

( 5) r e frac tive inde x, 

In addition, such properti es a s 

(6) si ,e distribution 

ra t io 

( 7) diffe rentia l scatte ring coeffi c i e nt 

\'Iere thoug ht t o be usef ul a s a n aid for a more complete unde rs t a nding 

of the opt i ca l e ff ec t s . Opt ica l properties 1-5 and 7 \·,ould a lso be 

s pec i f i ed a s a funct i on of Idavelength. 

e. Ra dioactivity in the atmosphere 

85 I t \'/dS rema rked that in the near fu t ure a byprod uct Kr of nuc l ear power gene ra t i ng plants wa s expected to ex i st i n co ncentrati ons 

that \·,i11 Signi fica ntl y i nc r ease th e conducti v ity of the a tmosphere on a 8S 

global basi s. Mo nitoring f.J' . a t background st a t i on s may become nec essa ry if the nun1 be r o f nuc l ear pD\'le r plants inc rea ses according to pre sent expectations . 

98 
Sec tion 2: Ground Truth 

A very important use of the GtKC baseline mon itoring stations ;s 

providing grou nd truth for satellite mea surements. One exampl e is 

tota l ozone measurements. The t otal ozone data from baseline and regional stati ons "ere used by the NUMBUS-D BUV exper iment team to qua lify 

results produced by thei r total ozone retri eval technique. 

a. Long-t erm obs ervat ion continuit y 

Although the Gf1CC program attempts to main tain time conti nuity in 

the measurements at baseline obs ervatories, such co ntinuity ;s more 

diffi cult to achi eve in satellite programs bec ause of the limi ted lifetime of s pace hard,·,are. It ,·,a s pointed out that GMCC can prov ide 

cont i nui ty in many important 1 on9- term measu rements of atmospheri C 

variables ,·,he re there ,·Ji ll be time gaps in satellite data. 

b . RecommendaUon for improvement of the U.S. total ozone measurement program 

I t \"las re co"':; ended that the U. S. total ozone network be upgraded to 

in:prove the quality and internal con sistency of the data. Also, the,'e 

should be an effort to obta in more uniform spacing of ob servation sites 

within the network. In connection with the upgr ading process. an exploration of new superior instrumentation and methods of' measurement 

s hould be undertaken \·/ithin the next fe\v yea rs. 

c. Remo te s ensing of ae roso l optical properti es 

Method s for dete rmining optica l properties of aerosols such as 

pha se function and refractive ind ex I'Jere di sc ussed. Mea s urement of 

tropospheric aerosols by satell ite for globa l coverage poses a difficult 

probl em becau se of the unknQ\vn refl ec tance of the underl y i n9 sUI"face. 

On the othe r hand, some pra c tical methods have been devised for inte,'-

pl"eting s pec ialized radiation measurements at the earth's surface. 

Di ffuse s kylight, po lariza tion, and tr ansmission of the direct solar 

beam are some of the s peciali zed measurements. 

often accompl is hed t hough the use of 11ie theory 

Interpreta tions are 

for sp herical particles 

and radiat iv e transfer ca lcul ations \'Ihereby variables such as size 

distribu tion and refractive index al"e deduced by virtue o f agreement 

99 
bet,'ieen ::heore t ic a l ca lcu1 13t io ns and meas u r" eme n ts. For ex a;npl e (a nd 

"rlthou t going into de t c)il) , ae i' oso l s i ze di st doL;tlons (needed fOl' 

ded uc ti on o f op tic a l prope rt ies) ha ve been estimdt ed fton so lar au reole 

mea s,twefTlents , a nd spectral me a su rements fo r t he exti nc t ion of the d il-ec t 

s o la r d:d ti on by a e t'oso ls. Als o , absorption of so lar l-ad iatl of) has 

been es ti n1{;t ed fron di ffus e s ky radia ti on data. The vari ous ne t hoos 

seell~ ::0 Yle l d eas o~l bl e r e sJ l ts. f'level- t el ess, most of them a r e qui te 

complic ated a nd employ as ll~ tions suc h as sphe ric al parti c l e s, ass umed 

r eal term f OI- the comp lex te fra c t ive index, and .a nal ytic al ex pre ss ions 

tha on5 ~a n he fOI-m of a n ae)·oc;.ol s iz e distri b tion . 

S ince muny of the me thods ha ve evolv ed f rom (ather recent resear ch 

and th cn~fal e are I-e la ti vely ne"I, the r'e has not been muc h oPPO I'tunity 

for o ·-gcllliz ed inte r-compl! l- ison f ot- veri fyino a- esults.* Su ch i n terconl -

p.afisons ".) uld undoubted ly be us efu l fOt' guidi ng a trros p lEric aerosol 

me asu renT'1t ro<:J ~-a r' s in the i l- selec ti on o f me t hod s and instrumenta tion. 

Sec ti on 3: I rra di dnce De t e rmilla tl on 

Fo ll o'.-:i ng a ShOft ta n on mea su remen t criter i a , there evo l ved 

d isc uss i on o n met hods of de te r.l. ~n in g a tmosph e r-i c turb idity usin<) the 

fa ln iliar Lanq l ey method\ and t1e less fa ni l i a r sol a r aureo l e method 

y/hi c r is sensi tiv e to 1m·;' l eve l s of t urbi dity. The Smithson ian As -

t l-op ll','sical Ob servato ry s o l a)' irradiance c: a t a ined by Abbo t (1908, 

1913) served as a special ex :~~ e of th e ~v 'lab e in f ormati on on 

)'ad iat i ve Il l-opel-tie s of a trros pheric subst an ce s . such as ae roso ls and 

ozone . The Smithsonian data are notel'lor-thy for t he great care exer c is ed 

hy the ex perinlen ters. 

" fl.li :.10rs ' no te: In vi e\·/ of t his. it may be \'lo r thl','I- il e to pol l th e 

r)r ill; ors o f illve';tioatOl-s 1'/110 \./ uld he ~_ e) es ted in an i nre l'com arison 

e .<p e ril'ent . Dir-ect s amplil1q me thod s could be inc lud ed i n th e in e r COrlli) 6l' ison as we l l . We offer t o ss s~ wi n r'a~ing suc h a po ll and orqa -

lli7 ' n'J d f 2rrUIi o n tile ~u bie c '; f i'lE 1',, 11 Sho\··s a rll-efe l-enc e t o dO so . 

100 
a. S I'face n'ea surements of so l ar l·ad ianc e 

T e fea si bility (an r r act i ca lity) of continuing the Smithsonia n 

so lar i rr ad i ance weasuref'ler. t s vias discussed , parti cul a rly in regayo to 

mea su r ement o f time var ill ti ons in the sola r flux . It \'Ias l"ema r'l.ed hat 

ab bot ' s dilta s howed no disce r nib e ti me va r iati on i n the so l ar co ns tant. 

-lO\'o'ev e r , m r e rece nt inves ti gations l- n~ r el-iodici ties in the far 

uv so l a r emi ss ion and l o ng t enll anQlllal ies in slJ nspot ac t i v ity such a s 

lne la unde r Hinil'lH.Jm "'Iere ci ted a s exanp les of tI.e 'Jar'l ahl e ncltU l' e of the 

su n . Th e l i ttle ice age of t he 1700' s was thoughL to be poss i bly caused 

by a va r' lation 1 11 the so l ar con s tant . A cons ens us o f opinions , Jodi -

ca t e d hat s ign ifi cant s ho rt- t erm var ia t ions in the sola r cons tan t were 

unli ely to (l cCt.r on a t }me sUll e of t he Il a nd 22 year cycl es . There 

~' /as unce l'ta inty \'Ihe t he l- the Zurich S UIlS,lOt. lIulnber COu ld rJe mean ing f ull y 

cO IT e l a t e d l'lith sn"a ll flu c tuati on s in the solar co nstant . 

It l'la s propo sed tha t Gi'~ C( r' onl to l- t he sola r l~adia ce ove r t l east 

a s ola r cyc l e and poss ib y lonfJe r. Some ilecrlS to (ons-i del fo)- s uch a 

il1eaSU1~e l"l nt gr a:J l \'Ier e noted as : 

1} v.rave l ength ra nge, banc~·li tll and fre qu e ncy o f obs erva ticms 

2) location and numbe l- of s i t es (ot he r cQuntr'ies invo l ved in an 

int erna~ l Dro gral;~ ) 

3) l1'o ni to r: ng of l oc al t!1~ os pheri c condi t i o ns dUI"in g pe r iods of 

rr e asu rer'ents (~'I hic h l"Iou ld inc l ude me a s ur . ents of 03 ' H20 , 

tu rb idit.y a nd th in 1n nO.1J(\I. <; cirrus) o 

4) s pec ial enph asis in th e 3000-4000A band 

b . Ac cur a c y of s UI"face sola r il-rad jallc e rr easurements 

An opi nion s tated in r ega ,-d t o e measu r eme nt of t e so la r con -

s tan t i npl ied t ha t trw acc ura cy of bl-oad - ba nd py r he liO'I€t ri c observa -

t i ons (fof e xan.plel could be achi e ved to ,·lithin 0 .1 ' f ae,-os01 'CaLte r i ng coul d be specif ied t o wit in 10 P.n ideal loc ati on fo)' a solar 

obs l" '1tH.o ry s uch as He-u n" Loa (o r PO~'i b1y so ut nr:le s te l"n .S. ) h(lutd 

a lso be ,·equir"ed . 

: . \1a S s~ 9g es te~ th~t sotel l i · e oh se rv inn nf · he so l a r cons t ant 

cou 10 be cllec ked ag ain s t : 11E s U1-f ace obsel-va ri cns ~l~hi n the limits 

glve n Ctbov e . 

101 
c, Stra t osp her ic aerosols 

Volcani cally pro duc ed stratosopheric ae ro so l s ca n cause a change in 

the earth's radiati on ba l a nce . Severe volcanic acti vity was considered 

a s a highly probabl e mec hani sm for inducing chan ges in c l ima t e. 

Monitoring of s tratosphedc ae rosols \'Ias recolTmended. Su gested 

met hods for monitoring \·/e r e by direc t measurements lIs ing ba lloon platforms and indirect meas ur ements using s urface-based optical t ec hniqu es 

such as twil igh t and lida r observations . 

d. Monitoring the terrestria l infrared 

The r e eme r ged the question of "/he ther Gt-1CC shoul d measure dOl'IOHard 

broadband infrar ed f lux. These data could be utilized to verify cl imate 

models that incorporat e ra diation ba lance calcul ations . The r e was some 

r eser va tion concerning ';lhe the r in f rared measureme nts a lone \'/e r e pra ct ic a l. Rather, infra red mea s urements might be i nte rpreted rro re meani ngfu ll y if specifi c meas ureme nt ep isodes were lI nd el tak n. suc h as an 

ex pe rime nt on cirrus cloud eff ec t s on outgo ing infra r ed fl ux. 

4. A note of appreciation 

Th e pet~son l of the Gi·KC ar e deel11y i nd ebted to the \·/Or king group 

parti cipants. The devotion of their time and energy, and the di splay of 

willingness to assist \;lith the missions of G/1CC a r e \'Iarmly appreciated . 

102 
References 

Abbot , C. G. , 1908: Ann. As trophy s. Obs. Smithsonian I nst., 2 . 

Abbot, C. G. , 191 3: An n. Astrophys. Obs . Smith son ian Inst. 3. 

GI1CC Annu a l SUlrmary Repo rts I, 1972, 19 73; 3, 1974 ; and 4, 197 5: 

U.S . Depa rtmen t of Com erce, Nati onal Oceani c and Atmos pheri c 

Admin istrat ion , En v ironmenta l Re search Laboratories, Boulder, 

Co lorad o. 

Junge, C., 1 975: The Phy sica l Ba s is of Cl imate and Climate 

Node ling ; Appendix 10, GARP Pub l ication Se ries ·io . 16, 

pp 2~ :; 251. 

Kondratyev, K. Ya., 1973: The Comp l ex Atmospheric Energetics 

Ex periment. GARP Pub li cation No. 12 , Jun e 1973, 43 pp. , 

\~MO, Geneva. 

103 
Work i ng Gr ou~ on GMCC ,.a di a: i on and Aerosol Meas ur ni s and th e ir Arpl icati ons 

re bnrc 'y 4-5, 1976 

R. MIGIOIIE \·1 . KEL LOGG (Chail'n'cfl, Section II) 

E. ~~R ETT H. m"iHY ~ 

F. BEAU J . LO:IDOt, 

B. OD~A! NE B. .'r: DO ~: A 

R. CHAR LSON A. 1' 1 LLER 

P . CHVL EK J . !-: I LLER 

J. COAK LE Y (ena i \1:1dli . Sec t ion II I ) G. 'IO n i 

H. COBB S. OL T',;AiJ$ 

S. COX J. PETERSOn 

R. CRAI·; R. PUESCHEl 

R. CULIIAN E ROB I'ISO: , 

J . DE LU ISI G. ROSI ~' SO:, (Chai l1na ll, Sectio n I ) 

J . ED Y C. RODGE RS 

R. ,EGLEY R. ROOS EI, 

E. 'LQ',.)[ RS H. SC'l1 FF 

J. GILLE O. SCHU En!·WI 

K. HAN SON ( Coveneur) G. SHA.·I 

R. A."S l H. SPRiGG 

O. EAT H A. HAGG OII ER 

O. HO T H. HEf en;,,:,:. 

J. !·IEI;:BERG 
'-" '" 

ST I·:I':; 

,\L (J ~illl !Ii" ~; leN. At.!O CliE~ll.C ,\L 

I'!(I)['I': I,;'I u::--, 

AE IW S(H. ()l" ~' J C .. \I. !) WP [RT ~ FS 

[(A !) r :\T! [)~[ TW;(l !{ Y 

/\ [' I' J.Y TO ~11)rwr. 

.~·:J~!·~Fc-l l.! 1~[1 ';( s r~ .':r) !r:I.S 

" t:, .H1:--.ICf. r H(l PO_&\ I." - .1 1) 7')* 

.'l(H:cJ. SpilC i....l~ d Ls Lrll)lICion o f 

"cro;ol cOIlCCnC fJ L_OIl Jil L: nilysiGl1 

:tnd C!h.'mlC<11 p n)\' l 'rt i.e." :I S l 

r UllcLillll 0: ';()IJl-(' ,,:, Dnu I' HH !i.f Ll:~ cion 

Ln lrn(l~;pll cT l:, Il', i " .1 ', l ::' l r..'ddy S(.llr..' 

t o i l eu LJ ( ion mu Ur..d , 

Ikt <..: fm inE" oc.n):..;oJ opc"ir..:n l for~r t.i. e~ 

l L'U !n clle .:JOOVC, 

----- -- -.-

I::',:l el i;) tion 

T! ~o ry 

< (Cluu d r!ly;;ics) 

~et rm in c (' {'fe ct o n 

~Jlll~ p r opl:rt \'L::-:i 

f{i.lcJ~dl on 

T~ll () y 

" f(:in r ~\ I O"-J MF i\ I\ r. !1':,\l....-':'!'~·! J." 

Dir. ' ct 1'1{; ,!Su r C:ilL'!lC of 

.1L' r u :;" l I_ i.I.:~ l :' -op~rltc'j 

(~ y r, dL !~ i un !!~(~;" '; t!I l:m 'nl 1 , 

,,"PI '!.)' TO Z()N,\L OR F: ~S {. 1. C! 1\C''1,,\"I' !(l\ :- o/) ,:~.s 

* 11111 )',,-' , c . !97 . :\..: r u:.. ,-d 1'/ '- l.: ~,~ L:! S in the 

IJIIV ~, i~,I : II.:J:--; i s o f C.:. inrd Cl: <1 \](1 L 1L )I;;.LLC ~lo( clinj.' . • 

i l [l '.', (I - ~ '.i 1 

FICl'RF. J 

APPENDIX B 

Spectral Turbidity Studies at Mauna Loa 

Suspended particulates, or aerosols, in the atmosphere scatter and 

absorb sunlight; they play an important role in climate because they 

cause localized heating or cooling within the atmosphere and at the 

Earth's surface. Since the industrial revolution, the concentration of 

smoke and pollution aerosols has risen dramatically and spread over 

large areas, perhaps even crossing oceans or penetrating to the polar 

regions. 

The University of Alaska Geophysical Institute in Fairbanks has 

conducted a 1-year study for GMCC to explore the possibility of using 

multiwavelength narrow-band sun photometry to monitor and quantify 

suspended aerosols. The advantage of the method is that it would 

measure aerosol properties through the whole atmosphere, and not just at 

or near the Earth's surface. 

The aerosol load (the total number or mass of aerosol in a vertical 

colwnn) is very small at locations such as Mauna Loa, and the extinction 

of sunlight caused by the aerosol is, of course, also small. But it is 

measurable, provided care is taken. One may be able to appreciate the 

difficulties involved by realizing that aerosols above Mauna Loa block 

out only about 1% of the direct solar beam, so the measures of sun 

intensity must be made to an accuracy of better than 1%, in fact, to 

about 0.1% accuracy. No commercial instruments were available that had 

the desired high accuracy and spectral resolution, so it was necessary 

to construct and characterize a stable multiwavelength photometer. 

Measurements of atmospheric transmission were made with this photometer 

every clear day from March to August 1976, and during an exceptionally 

clear and dry period in January 1977. 

The measures of atmospheric extinction were made in the visible and 

near-ultraviolet spectral region at 12 individual narrow wavelength 

bands about 100A wide in the spectral region 400 to 1000 rum. Narrow 

wavelength bands permit use of the classic Langley technique to derive 

atmospheric extinction. This is an advantage that older broadband 

turbidity instruments do not have. Use of the Langley method on a dayby-day basis provided an independent instrument calibration for each 

observation period, and allowed the special photometer to demonstrate 

its extreme stability; it changed in sensitivity by only one or twotenths of 1% during almost a full year of field activities. 

Results of the experimental study for nearly 100 clear days indicate that there is always some slight amount of haze present, even above 

Mauna Loa in the central Pacific. An interesting and important finding 

is that there tended t~ be almost no connection between surface aerosol 

concentration at the observatory, and variation in total aerosol optical 

extinction through the whole atmosphere above the observatory. Nor was 

107 
ther e any particular correlation between the observatory's local meteorologi c al parameters a nd the optical a e rosol extinction. Th i s finding 

suggest s that the aerosols above Mauna Loa have formed in s itu or were 

brought in by winds from distant sourc e s--tbat is, the opti c al extinction me a surements are proba bly representati ve of the entire mi ddle 

Pacifi c a rea, and can be de s cribed as "ba c kground aerosols!!. Obviously 

it is import a nt to determine what these ba c kground aerosols are, where 

they came from a nd how they arrived in the air ove r such a distant 

observatory . By looking at air trajectories goi ng back about 1000 km, 

and classifying the trajectori e s a c c o rding to a z imuth, it was learned 

that the opti c al e x tinction was some what larger duri ng times when the 

wind had blown from the North Ameri c an co ntinent. Th e c leanest sector 

was air that had come from south of Hawaii. The inc rease a nd decrease 

of turbidity associated with specifi c a ir masses seemed to be superimp o sed on a fairly co ns tant curve of optica l extinction. That can he 

surmi se d to result from the stratospheri c s ulfate layer that is almost 

perpetually present everywhere on Earth. 

Figure A. I s hows the average values of aerosol optical thi c kn ess 

(base e) at 11 wa velengths above the observatory during the period Ma rch 

to August 19 76 . There is reason to believe that the optical thi c kness 

a t the two longe s t wavelengths in Figure A.l are s omewhat over-estimated 

be c ause of a slightly absorbing wat e r vapor continuum that affects the 

e ntire red and n ea r-infrared portion of the spectrum. The aerosols 

pr e v e nt about 2% 6f blue light and le ss than 1% of red light in the 

dire c t solar beam from rea c hing the summit of the observatory. When the 

ave rage aerosol extinction spectrum i s weighted by the solar intensity 

- 10",-----,-----,---,---,---,--, 

-03~~-- 0 .11 --OS --~~--~--~ 0.6 0.7 O.B 0~~ .9 1.0 

lOB 

Fi g ure A.l. Mean a e rosol optical 

thi c kne ss at Ma una Loa f or MarchAugus t 1 9 76. 
and integr ated over wavelength, one finds that aerosols in the central 

Pacifi c block 1% of the total radiant e nergy in d irect sunlight when the 

sun is at the zenith. 

In Figure A.2 the frequency distribution of aerosol-pIus-ozone 

optical thicknesses are shown for 12 identical sampl ed wavelengths. 

Filter 11, at 950 nm , is in the center o f the strongly absorbing pat 

water vapor bands, and fil ter 6 is in the center of the Chappuis ozone 

bands . 

The studies on sun photometry have led to several areas of investigation additional to aeroso l physi cs. For example, the amount of water 

vapor dissolved in the air \vithin a vertical column has been inferred 

fr om optica l absorpti o n in the near-infra red water vapor bands to be 

typically about 0.1 g cm- 2 

'2 

n~ 10 

)"\~~ ________ ~n __ _ 

8 

c'l--..alCo I[kMLC,--I)='1fp'---"--- 'l--L0,----"O-,-, _-"', ,.----nonJo A-"----'illO ,",-00 _--" __ ----"----___ , 

CJ 02 0 ·: C6 ' 0 

e . . ,'- ~ I. ' I LJ 

J[J 02 0 6 

~o 1 

Co 

Fi g ure A .2. Frequency dis tribution for ozone-plus - aerosol optical 

thickness at 11LO for 85 days from March to August 19 77 _ The numb e r s are sampl ed t.;avelengths numbered sequentially from blue to 

red: No.1, 401 nm; No .2, 422 nm; No .3, 486 nm; No .4, 521 nm; 

No.5, 537 nm; No.6, 611 nm; No.7, 659 nm; No . 8 , 669 nm; No. 9, 

750 nm; No. 10, 860 nm; No. 11, 947 nm; No . 12, 1010 nm. 

109 

, 0 
Atmospheric ozone has also been measured by sun photometry with 

accuracies comparable with those obtained by measuring absorption of 

yellow light in the Chappu is bands with a Dobson spectrophotometer. Our 

pre liminary findings show good correlation with Dobson-derived oz one 

amounts, but there is an unexplained systematic difference between ozone 

amounts inferred by the two independent techniques. The Chappuis b and 

determination gives larger values for atmospheric ozone than do the 

Dobson values. 

Perhaps the most important result of this research concerns the 

sun's spectral irrad iance. The study has shown that the sun's spectral 

irradiance (extrapolated through the atmosphere by using the Langley 

method) WaS constant to an accuracy better than 0.3% oveL 9 months; the 

extremely clear and stable observing co nditions at Mauna Loa, as documented by this program, s h ow that it would be a superb location for 

lnaking solar spec tral irradiance measurements. 

*U.S. GOVE~~~NT PRINTING OFFICE:1994-673-018/00C48 

110