U.S. DEPARTMENT 

OF COMMERCE 

NATIONAL 

OCEANIC AND 

ATMOSPHERIC 

Geophysical Monitoring 

for Climatic Change 

No. 4 

Summarv Report 1975 

( 

. 

., 
U.S. DEPARTMENT OF COMMERCE 

Elliot L. Richardson , Secretary 

NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION 

Robert M. White, Administrator 

ENVIRONMENTAL RESEARCH LABORATORIES 

Wilmot N. Hess, Director 

GEOPHYSICAL MONITORING FOR CLIMATIC CHANGE 

NO. 4 

BOULDER, COLO. 

August 1976 

SUMMARY REPORT 1975 

James A. Watkins, Editor 

GEOPHYSICAL MONITORING FOR CLIMATIC CHANGE 

NO. 4 

SUMMARY REPORT - 1975 

1. SUMMARY 

The highlight of 1975 was the completion of the fourth GMCC Observatory 

at American Samoa . This is the final baseline - type observatory in present 

planning; future effort will concentrate on bringing full program l evels to 

these four observatori es. 

The National Science Foundation opened the new Sout h Pole Station in 

earl y 1975 and c l osed the o l d Stati on that was built i n 1957 . The new station l ocation (about 1 km away) necessi tated rel ocati on of the GMCC program. 

For this purpose a small temporary building was constructed and placed j ust 

below the snow surface about 120 meters upwind of the new Station . This 

served the GMCC program adequately during 1975 . A more permanent above-thesnow structure is being planned by NSF and NOAA for construction during the 

19"/6-77 austral summer season. 

Automati c data acqui sition systems (ICDAS) have been install ed a t all 

four GMCC Observatories. These systems l og the data on magnetic tapes which 

a r e shipped to the GMCC offices in Boulder for processing. In the area of 

measurement techniques , noteworthy accomplishments were (1) the development 

of a "through-the -analyzer " flask exposur e syst em and (2) the acquisitio n of 

three nephel ometers to complete the requirements for such measurements at the 

four observatories. 

In July 1975, Mr. Donald Pack , Director of the GMCC Program s ince its 

inceptio n , retired. His many friends and associates in the Program take this 

me an s of expressing their sincere thanks for all he has done over the years 

(71-75) to guide this Program from the dream of long-term monito ring to its 

present l evel . These people also wish him the best of health, enjoyment , and 

sati sfaction in the years to come. 

A new organization group has been formed , the Data Acquisition and 

Management Group , to carry out the f unction of acquiring , processing , and 

archiving the observatory measurements. Thus, the GMCC now has the following 

organizational structure with headquarters in Boulder and four observatories. 

TECHNIQUES l 

STOS. CROUP 

MAUHA LOA OBS. 

ACQUISITION l 

DATA MGMT. CR. 

SOU TH POLE OBS. 

DIRECTOR 

BARROW OBS. 

ANALYSIS l 

IHTERP. CR. 

SAMOA OBS. 
2. OBSERVATORY FACILITIES 

This section documents changes in e xisting physical facilities or addition of new facilities at the observatories that are r e l evant to the c haracter and quality of the measurements being made. Simple relocation of monitoring systems or installation of new systems is covered in Section 3. 

2. 1 Mauna Loa 

A small portable trailer was modified during the first quarter of 1975 

to temporarily house a portable lidar system being developed for the Barrow 

Observatory. A s helf and an instrument rack were fabricated and installed in 

t h e trailer. 

In March , a Telex mac hine (number 633145) was installed in the Hilo 

office to provide an alternate means of communication with various stateside 

offices and to reduce the monthly phon e costs. 

The Instrument Control and Data Acquisition System (ICDAS) and several 

major pieces of equipment were damaged during a lightning storm in early December. Although most of the equipment was returned to operation in a relatively short time , the ICDAS remained down until early January 1976, resulting in considerable loss of data. This event emphasizes the need to provide 

better electrical grounding against lightning strikes for the fac ilities at 

Mauna Loa . Possible solutions for this problem will be investigated in 1976. 

2 .2 Barrow 

Several fac ility improvements were made to the Barrow Observatory during 

1975. A power cable was installed to t he 17-meter meteorological sampling 

tower NE of the station. Several c ircuits in the main building and the 

Dobson platform were rewired to provide better power distribution. A 3.6-

meter-square wooden sampling platform was constructed and wired for a cooperative Energy Research and Development Agency (ERDA) air sampling program. 

Access to the roof p l atform of the main building was improved with the addition of stairs, and two windows were added to provide greater visibility. A 

new refrigerator/stove/sink unit was put into ser v i ce and a 94-liter water 

storage tank was insta lled . Stati on security was improved by installation 

of locks on all doors and floodlights to illuminate the main building during 

dark periods . 

A Bombardier "Bombi", a small , tracked , all-terrain vehicle , arrived in 

July and provided access to the station during summer thawing and winter 

storms. A c hain gate was p laced across the road to deter unauthori zed visitors and a sign was constructed to identify the station and its require ment 

for " c lean air " monitoring . As a result of limiting traffic during the summer thaw, the road remained in excell ent condition through most of the winter. 

2 
Fi g . 1 is an aerial view of the Point Barrow complex prior to construc -

tion of GMCC station . 

Figure 1. Point Barrow complex in 1971 . A - Naval Arctic Research 

Laboratories. B - POW- Main DEW Station (USAF). C - Location of 

GMCC Observatory (constructed in 1972). 

3 
2.3 So uth Pole 

1975 was marked by the long-awaited opening of the new U.S. South Pole 

Station with its 16-meter-high a lumin um geodesic dome, afte r nearly four 

austral summers of construction. The n ew station is approximately a kilometer from the o rig inal station that was built during the IGY . On December 

14, 1974, radio commun i cations gear was s witched t o the new station and the 

first residents moved i n. On December 27 , the symbolic barber-shop-striped 

South Pole and surrounding f l ags of the 18 Antarctic Treaty nations were 

moved t o a spot near the new station e ntrance. Political leaders , administrators, scientists , and logisticians from the United States and other countries dedicated the new U.S. Amundsen-Scott South Pole Station i n ceremonies 

at the site on January 9 , 1975. 

The GMCC p r ogram was removed from the Aurora Tower at o l d Pole Station 

and transferred to a temporary under- snow facility located about 1 20 meters 

grid northeast of the sky laboratory in the science quadrant of the new Pole 

Station (Fig. 2). Constructed of p l ywood and old shipping crates, this 

" c lean air " facility i s to serve as t emporary housing for those programs, 

like GMCC, whose requirements are to monitor a tmospheric parameters free from 

local contamination a majority of the time (figs. 3 and 4). It i s intended 

to last 2 to 3 years while a n ew, mo r e permanent , structure is designed and 

built. The structure was trenched below the snow surface to avo id appreciabl e drifting of snow downwind atop other sensors and equipme nt l ocated in 

the science quadrant . Entrance is gained by a 1.5-meter-square vertical 

s haft located in a corner of the building. The facility has a usable f loor 

area of 47 square meters (504 square f eet) of which 34 square meters (360 

square f ee t) are dedicated to GMCC ' s use. 

By mid-January, construction wa s nea rly complete and about 80% of the 

monitoring programs had been relocated. The aerosol/gas sampling stacks were 

erected with the help of a c r ane. The intakes are about 6 meters above the 

surrounding snow s urf ace and point into the predominant wind direction which 

is 20° east of grid north. In late January , the skid-mounted Dobson spectrophotometer and ERDA sampling huts were pulled by tractor from their old locations near the Au rora Tower to their new locations near the "clean air" facility and the area around the facility was backfilled with snow. A metal 

pedestal was fabricated to mount a 13-channel pyrhel iometer north of the 

facility and a 3-meter square woode n platform was constructed to mount other 

solar radiation sensors. Figure 4 shows the location of the facility relative to surrounding structures and equipment. 

By the end of the austral winter, the facility was beginning to show 

signs of compressi on due to an increasing snow load on the roof. The ceiling 

had begun to sag near the center and one support post had cracked. Pl ans 

were made t o add more support beams for the ceiling and to extend the vertical access shaft by 1 meter duri ng the austral summer. 

4 
i 

Figure 2 . Aerial view of the n ew South Pole Station, with the "clean air" 

facility marked . 

2.4 Samoa 

The GMCC program is greatly indebted to t h e Government of American Samoa 

and to High Chief Iuli Togi for their assistance in establishing the Samoa 

GMCC Observatory . Construction of the Samoa GMCC Observatory was completed 

in September 1975. By late December most of the i nstrumentation a nd the 

data acquis ition system were installed . On November 27 the Observatory was 

dedicated in a ceremony attended b y the officials of NOAA, t h e Government of 

American Samoa , and t h e l ocal Samoan chiefs and d i gnitatries (Fi g. 6 ). I n 

January 1976 , t he Observatory b ecame fully operational. 

Access to t he o bservatory i s provided by a paved , singl e-lane road , 

which ties into the main island road in Tula Village . The road was originall y paved in Marc h , but heavy construction traffic damaged much of the surfacing, and repaving was necessary in November . A chain gate was p laced 

across the road to minimize unnecessary traffic and its resulting pollution . 

The 27x5 m building (Fig. 7) i s locat ed at 170°33 ' 46 "W, 14°15 '08 "S , with 

an elevati on of about 77 . 4 m above mean sea level. The building is fully a i r 

conditioned to protect the computer a n d instrumentation from rather high 

ambient humidity. Building water is supplied by a water catchmen t system. 

Water i s coll ect ed on the upper observation deck and stored i n a 38-kl u nderground c i stern. 

5 
( 

Figure 3 . Temporary clean-air facility prior to snow burial. 

f PREVAr--ILIN G WIND ---------

SAMPLING STACK 

24' 0" -----------~ 

N 

ECC 

REGNER-EJ 

rn 

ITABLEI 

rn 

COAT 

RACK 

ACCESS 

SHAFT 

POLLAK L-------- FREEZEREJI 17 C02 &. C2H4 TANl\S 

G._AR ....... DN_E_R _ _, ~=ME~C ~---. fEMfiil 

ECC C02 ~ !2..J 

~ 

DESK 

WORK 

BENCH 

GE 

CABINET 

CABINET 

FI LE 

FILE 

ATMOS. ELEC. &. 

RIOMETER 

EOF CALIFOR NIA 

,-"' 

I 

IHI-VOLi 

L_-1 

UNIVERSITY 

OF WORK 

MARYLAN D BENCH 

WORK BENCH 

T 

ACCESS 

PANEL 

SAMPLING 

STACK 

I 

2r o· 

Figure 4. Clean air facility - 1975, South Pole Station, Antarctica. 

6 
Univ. of Col. 

Davis a 

Slonford 

Aulomolic Weolher 

Station 

\ (N Prevailing ' Wind 

Cleon Air 

Quadrant 

13 Channel 

'i\ Pyrheliometer 

1 Pedestal 

601 

-~ 

ERL 

Almospheric 

Eleclricily 

850' lo Riomeler -=======~ --- --- - --- - --------- -

Solar 

Rodiolion 

Plolform 

ERL 

Acouslic 

Sounder 

Coble leads 

Primary power 

Figure 5. Surface diagram of science quadrant at South Pole Station. 

A 100-kW diesel emergency generator (Fig. 8) became operational in 

November to supplement commercial power in times of power outage or fluctuation. The ICDAS system is equipped with an uninterruptible power supply to 

minimize data loss when the generator is switched on or off. 

Cape Matatula was the site of a U.S. Marine radar station in World War 

II. Many of the original foundations had to be demolished, and Lauagae Ridge 

was landscaped in September to provide about 3000 m2 of useful land adjacent 

to the Observatory building. In December a 183-m fence was added at the SE 

precipice of the Ridge for personnel protection . 

A wooden stairway (Fig . 9) was comp leted in November between Lauagae 

Ridge and Matatula Point , a vertical drop of about 50 m. 

7 
Figure 6. Ribbon cutting at Samoa Observatory dedication. L . to R. Chief 

Iuli Togi, Tula Village; Mr. Joseph 0 . Fletcher, Deputy Director, ERL; 

Honorabl e Te'o, Speaker of the Samoan House. 

Figure 7. Samoa GMCC Observatory building. 

8 
--

Figure 8. Samoa emergency generator 

facility 

Figure 9. Access stairway from 

Lauagae Ridge to Matatula Point. 

In December a 9-m air sampli ng tower was erected as part of a cooperative program by the University of Rhode Island under the direction of Dr . 

Robert Duce and funded by the National 6FLHQaHFoundation. An unde rground 

power line was i nstalled to provide power for this program on the Point . 

Solar radiation sensors, a URAS C02 analyzer, a Dobson ozone spectrophotometer , and two surface ozone monitors were installed also in December. The 

radiation sensors and Dobson Ash Dome are located on the upper observation 

deck. The ECC and Dasibi ozone meters sample air through Tefl on tubing fastened to a s hort mast erected on the observation deck. The URAS C02 anal yzer 

samples air through a 335-m polyethylene tube secured to the U.R.I. tower on 

Matatul a Point . Meteorology sensors were also installed on the tower , wi th 

s ignal cables connected to ICDAS inside the building . 

Plans for 1 976 i nclude erection of a remote sampling shelter near the 

top of the acce.ss stairway on Lauagae Ridge and a 20-m sampling tower. This 

install ation will be used for aerosol and other selected gas monitoring programs. 

9 
2 . 5 Boul der 

Space has been obtained at NOAA ' s Fritz Peak Observatory, in Colorado 

f or the purpose of conducting selected measurement programs (particul a rly 

sur f a ce ozone observations), as well as for testing instruments at a r e l a -

tive l y clean-air si te. The observatory is operated by the ERL Aer onomy 

Labora tor y . It is located south of Nederland, Colorado about 25 miles west 

of Boulder. 

El evation of the observatory site is 8,000 feet above mean sea l e ve l, 

whil e Fritz Peak itsel f rises to an altitude of 9,020 feet. Col orado Highway 

119 r uns past the observatory and although relatively heavy traffi c pr evails 

during weekends , parti cuarly in the summertime, a predominance o f c l e an air 

i s avail abl e at the site during much of the year. Prevailing winds a r e from 

the west, from the d i rection of the Rocky Mountain Great Divide. 

10 
3. OBSERVATORY PROGRAMS 

This section summarizes the measurement programs and documents any 

changes such as r elocati on , new installation, on-station modification , or 

discontinuation of any program or system. A brief description of both probl ems and solutions is included . 

3 .1 Mauna Loa 

Side-by-side operation of the GMCC URAS-2 and the Scripps Applied 

Physics carbon dioxide continuous analyzers continued through 1975 in order 

t o obtain a substantial set of comparative data. The URAS-2 analyzer was 

modified to operate either by computer control or independently when the 

computer is not available for data acquistion. 

The lidar program was e xpanded to include aerosol profiles in the upper 

troposphere in addition to those previously measured in the stratosphere. 

Also using data from the MLO lidar system, a program was initiated to determine the statistics of occurrence of cirrus clouds in the upper troposphere . 

These measurements include height, thickness, frequency of occurrence during 

various seasons, and optical thickness. 

In the evening , during downslope wind conditions, flask sampl es were 

taken for fluorocarbon measurement. Previously , samples were taken during 

the daytime generally at the time of upslope winds. 

In September Eppley bulb pyranometers NWS 1825 and NWS 1833 , used for 

global radiation measurement over the past 9 years and 5 years respectively, 

were disconnected and returned to the National Weather Service Engineering 

Division for terminal calibrations. Pyranometer NWS 1825 was intercompared 

for one month with the GMCC Eppley Model II (12616 F3) pyranometer before 

being returned. 

A new e x ecutive program , Basic Operating Software System (BOSS) 75170, 

was installed in the GMCC data acquisition VaVWHP (ICDAS). It acquires and 

records signals from the different sensors at the observatory and controls 

the cal ibration cycles on some sensors. The installation was completed and 

tested during the sununer and the previously used Hewlett-Packard data acquisition system was terminated in October. Backup solar radiation data were 

also recorded on a 24-channel Leeds & Northrup recorder and a Honeywell-Brown 

r ecorder. 

Mauna Loa acted as a central calibration and operational testing facili ty for a number of new aerosol instruments designed for use at the other 

baseline stations. A modified General Electric Condensation Nucleus Counter 

and a four-wavelength nephelometer were tested and operated during the year 

and will be transferred to the Barrow Observatory in 1976. In addi tion , 

three long-tube Gardner counters and three Pollak counters were tested and 

compared with the MLO Poll ak counter. 

11 
New sensors for atmospheric pressure, temperature, and relative humidity 

were installed to provide an electrical output with a linear calibration 

factor. In addition, a set of linear translators was provided to produce a 

uniform voltage for wind direction and speed. This installation was comp l eted in November. 

There were three short-term cooperative programs at Mauna Loa in 1975 . 

During September , Dr. Jost Heintzenberg of the Institute of Meteorology , 

Johannes Gutenberg University, Mainz , Germany, visited the Observatory to 

demonstrate his new inversion technique which determines the in situ size 

distribution of the high tropospheric background aerosol. 

In July a cooperative effort with Dr. Keith Bigg, CSIRO , Australia , was 

conducted to determine some of the chemical properties of Mauna Loa aerosols. 

Dr. C. Murray Penney of the General Electric Corporate Research and 

Development Laboratories, Schenectady, N.Y., made an attempt in late 1975 to 

measure the profile of atmospheric ozone using an ultraviol et lidar system. 

Mauna Loa programs operated during 1975 are listed in Table 1 . 

3.2 Barrow 

The instrumentation control and data acquisiti on system (ICDAS) was installed at the station in April. Operation began with BOSS 75070 and was 

upgraded to BOSS 75170 during the summer. The system ran well during most 

of the year; however, a two-day power outage in November caused a computer 

failure that was not solved for over two months. New meteorological sensors 

were installed to measure relative humidity, air and ground temperatur e , barometric pressure, and wind speed and direction. All of these parameters are 

now fed directly into the ICDAS. 

During the summer the Smithsonian Radiation Biology Laboratory (SRBL) 

cooperative program added a scanning UV radiometer to its array of pyranometers on the roof platform. 

Two new cooperative measurement systems were added to the station ' s 

progrnms. These are: 1) a prototype spectrometer to measure stratospheric 

N02 for NOAA ' s Aeronomy Laboratory , Boulder, Colorado; and 2 ) a high-volume 

air sampler for surface aerosol measurements for the ERDA Health and Safety 

Laboratory , New York. The latter system was installed on the new ERDA platform together with three other high-volume samplers operated for the Desert 

Research Institute. 

New ECC and Dasibi surface ozone instruments were installed in July and 

a Pollak condensation nucleus counter and a new C02 UNOR analyzer were also 

put on-line during the summer. Table 2 lists those programs in operati on at 

Barrow. 

12 
Table 1. 

Monitoring Programs 

Gases 

Carbon dioxide 

Surf ace ozone 

Total ozone 

Fluorocarbons 

Aerosols 

Atmospheric particulates 

(height distribution) 

Condensation nuclei 

Optical properties 

Solar Radiation 

Global spectral 

irradiance 

Dir ect spectral 

irradiance 

Water vapor 

Solar aureole 

Meteorology 

Temperature/dewpoint 

Pressure 

Precipitation 

Preci pitation 

chemistry-GMCC 

Winds 

Cirrus c l ouds 

Cooperative Programs 

Carhon monoxide-Max 

Planck Inst. 

S02 , NOx , NH 3 , H2S 

NCAR 

S02, N02 - EPA 

Total surface particulates - ERDA 

Turbidity - EPA 

Precipitation chemistryEPA 

Rain sr90 - ERDA 

Aerosol particles for 

analysis - CSIRO 

Surface Tritium - U. of 

Miami 

Solar Radiation 

Erythema SpectrumTemple Un iv . 

1975 Summary of Sampling Programs at Mauna Loa 

Instrument 

Evacuated Glass Flask (SIO) 

Applied Physics infrared 

gas analyzer (SIO) 

URAS-2 infrared gas analyzer 

Electrochemical concentration cell (ECC) 

Dasibi ozone meter 

Dobson spectrophotometer 

Evacuated flask 

Lidar 

Gardner counter 

General Elec tric counter 

Pollak counter 

Four-wavelength nephelometer 

Ultraviolet radiometer 

Four Eppley pyranometers 

Eppley bulb-type pyranometer 

Eppley normal incidence 

pyrheliometer 

Foskett 

Aureole camera 

Hydrothermograph 

Barograph 

8" raingage 

Tipping bucket gage 

pH meter , bridge , 

electrodes 

Anemometer 

Lidar 

Chemical reaction with HgO 

Chemical bubbler system 

Chemical bubbler system 

Hi-volume filter 

Dual wavel ength sunphotometer 

Misco collector 

Ion exchange column 

Impactor/precipitator 

Molecular sieve 

Ultraviol e t meter 

13 

Sampl ing Frequency 

2/month 

Continuous 

Continuous 

Continuous 

Continuous 

Disc r ete 

l / week 

l/week 

Discrete 

Continuous 

Discrete 

Continuous 

Continuous 

Continuous 

Continuous 

Continuous 

Continuous 

l/week 

Continuous 

Continuous 

Daily 

Conti nuous 

Discrete 

Continuous 

l/week 

Continuous 

1/2 weeks 

1/2 weeks 

Intermittent 

Di screte 

Discrete 

l/month 

Discrete 

2- day averages 

Conti nuous 

Data Record 

Oct 1958 - present 

Oct 1958 - present 

June 1974 - present 

Sept 1973 - present 

July 1975 - present 

Oct 1957 - present 

Sept 1973 - present 

Apr 1973 - present 

Sept 1967 - present 

Sept 1973 - present 

July 1973 - present 

Jan 1974 - present 

Apr 1972 - present 

May 1972 - present 

J an 1958 - Sept 1975 

Jan 1958 - present 

J uly 1967 - present 

June 1974 - present 

1955 - present 

1955 - present 

Dec 1956 - present 

Dec 1956 - present 

Oct 1974 - present 

Dec 1956 - present 

Apr 1973 - present 

Aug 1973 - present 

- July 1975 

Aug 1971 - present 

1970 ' s - present 

1960 's - present 

Mar 1973 - present 

Nov 1955 - present 

Aug 1971 - present 

Aug 1971 - present 

Dec 1973 - present 
Table 2. 

Monitoring Programs 

Gases 

Carbon dioxide 

Total ozone 

Sur face ozone 

Fluorocarbons 

Aerosols 

Condensation nucl ei 

Solar Radiation 

Global spectral 

irradiance 

Meteorology 

Temperature 

Dewpoint temperature 

Pressure 

Precipitation 

Snow cover 

Wind speed/ direction 

Air & ground 

temperatures 

Relative humidity 

Pr essure 

Cooperative Programs 

Turbidity - ERDA 

Precipitation chemistry - EPA 

Sfc . global radiation - SRBL 

Tota l surface 

particulates - ORI 

COz sampling -Scripps 

Total surface particulates - ERDA 

Total NOz -Aeronomy 

Lab , NOAA 

1975 Summary of Sampling Programs at Barrow 

Instrument 

UNOR infrared gas analyzer 

Evacuated glass flask 

Dobson spectrophotometer 

Electrochemical concentration cell (ECC) 

Dasibi ozone meter 

Evacuated flask 

Gardner counter 

G.E. condensation nucleus 

counter 

Pollak counte r 

Four Eppley pyranometers 

Ultraviolet radiometer 

Hygrotherrnograph 

Hygrotherrnograph 

Mi crobarograph 

8" raingage 

Observer 

Bendix aerovane 

Remote sensors (thermisto r s) 

Remote sen sor 

Transducer 

Dual wavelength sunphotometer 

Misco collector 

Eppley pyranometers 

Scanning UV radiometer 

Hi-volume sampler 

Evacuated flask 

Hi-volume sampl er 

N02 spectromet e r 

3 . 3 South Pole 

Sampling Frequency 

Continuous 

l/week 

Discrete 

Continuous 

Continuous 

l/week 

Discrete 

Continuo us 

Discrete 

Continuous 

Continuous 

Continuous 

Continuous 

Continuous 

Discrete 

Discrete 

Continuous 

Continuous 

Continuous 

Cont inuous 

Discrete 

Disc rete 

Continuous 

Continuous 

Continuous 

2/rnonth 

Continuous 

Discrete 

Data Record 

Mar 1973 - p r esent 

Apr 1971 - present 

Aug 1973 - present 

Mar 1973 - present 

July 1975 - present 

Sept 1973 - present 

Sept 1971 - p resent 

May 1973 - Nov 1974 

Oct 1975 - present 

June 1974 - present 

June 1974 - present 

Feb 1973 - present 

Feb 1973 - p resent 

Feb 1973 - present 

Feb 1973 - presen t 

Oct 1974 - p resent 

Feb 1973 - present 

Nov 1975 - present 

Nov 1975 - presen t 

Nov 1975 - present 

Mar 1973 - present 

Sept 1973 - Sept 1975 

Apr 1973 - present 

May 1975 - present 

Oct 1973 - present 

Jan 1974 - present 

Aug 1975 - present 

Aug 1975 - present 

Table 3 l i sts GMCC and cooperative programs that were in operation at 

Sou~h Pole Station ( "Pole") during 1975. Following is a brief review of 

equipment performance and some of the operational difficulti es. 

14 
Table 3. 1975 Summary of Sampling Programs at South Pole Station 

Monitoring Prograjlls 

Gases 

Car bon dioxide 

Surf ace ozone 

Total ozone 

Aerosols 

Condensation nuclei 

Solar Radiation 

Global spectral 

irradiance 

Meteorology 

Temperature 

Pressure 

Wind speed/direction 

Cooperative Programs 

C02 sampling - Scripps 

Total surface pa ~ticulates - ERDA 

Turbidity - ERDA 

C14 sampling 

3 .3.l Carbon Dioxide 

Instrument 

URAS infrared gas 

analyzer 

Evacuated glass flask 

Electrochemical concentration cell (ECC) 

Chemiluminescent meter (MEC) 

Dobson spectrophotometer 

General Electric counter 

Pollak counter 

Four Eppley pyranometers 

Ultraviolet radiometer 

Normal incidence pyrheliometer 

Thermistor 

Transducer 

Bendix aerovane 

Evacuated glass flask 

Dual wavelength s unphotometer 

Pressurized steel flask 

Sampling Frequency 

Continuous 

2/month 

Continuous 

Continuous 

Discrete 

Continuous 

Discrete 

Continuous 

during daylight period 

Continuous 

during daylight period 

Continuous 

during daylight period 

Summer only 

Continuous 

Continuous 

l/week 

Discrete 

l/week 

Data 

Jan 1975 

Jan 1975 

Dec 1971 

Jan 1974 

Dec 1963 

Jan 1974 

Jan 1974 

Feb 1974 

Feb 1974 

Oct 1975 

Dec 1975 

Dec 1975 

Dec 1975 

1955 

M"Y 1970 

Jan 1974 

J an 1974 

Record 

- present 

- present 

- present 

- present 

- present 

- present 

- present 

- present 

- present 

- present 

- present 

- present 

- present 

- present 

- present 

- present 

- present 

Continuous C02 monitoring at Pole commenced in mid-January 1975 at the 

"c l ean air" facility with a URAS-2T continuous analyzer (serial number 029), 

and proceeded substantial ly uninterrupted to the end of the year . The analyzer obtained samples of outsi de a ir through aluminum tubing approximately 

10 meters long that extended t o the top of the sampling manifold stack , and 

the output was recorded with a Hewlett-Packard 7127A Strip Chart Recorder. 

The analyzer exhibited a persistent monotonic downscale drift throughout most 

of the year. Despite thorough investigation of the e lectronic, mechanical, 

and optical components of the URAS - 2T, the reason for this drift was not 

discovered. 

A flask C02-sampling apparatus was added to the South Pole C02 analyzer 

system in mid-January 1975 . This apparatus allows simultaneous filling of 

pairs of flasks by the air-input plumbing of the URAS-2T C02 analyzer. During 1975, flasks samples were collected on or about the first and f ifteenth 

day o f each month. These sampl ing dates and times were chosen to coincide as 

nearly as possible with the sampling dates and times that had been established 

15 
by the Scripps Insti tution of Oceanography for its f l ask sampling program (a 

cooperative program for which GMCC has responsibility for making measurements) . 

3.3 . 2 Surface Ozone 

Surface ozone monitoring by the McMill an (MEC) -llOO c_hemiluminescent 

ozone analyzer (seri a l number 362) at ol d Pol e was interrupted in mid-November 1974 when t he r otor shaft bearings of that instr uments ' s air pump seized . 

Monitoring was not resumed until mi d-January 1975 after repairs to the pump 

and after the transfer of t he GMCC program to new Pole. The operation of the 

MEC-1100 was twi ce mor e interrupted by failures of the air pump. After its 

third failure , the pump was replaced and no further probl ems were experi enced. 

Surface ozone monitoring at new Pole was also conducted with an ECC-005 

electrochemical concentration cell ozone meter (serial number 2) that arrived 

from Boulder in mi d-January . Despi te the recurrent mal function and eventual 

failure (in early November 1975) of an electrically-operated valve that 

selected ambient or filtered air inputs to the e l ectrochemical concentration 

cell, the ECC- 005 per formed satisfactorily from mid- January 1975 until the 

end of the year. 

Surface ozone monitoring with the ECC-002 (serial number 503) continued 

from mid-January until mi d-November 1975. The most vexing probl em with the 

ECC-002 was its noi sy output , which became noisier as the year progressed. 

The noise was not caused by contaminated sensing solution, by mechanical 

vibration , by the sensor ' s electronics, or by contamination of the sensor itsel f . The exact source of the noise was not discovered. 

The Regener ozone generator (serial number 28) that had been used at old 

Pol e and an MEC-1000 ozone generator (serial number 314) were avail able at 

new Pole to provide sources of ozone wi th which to cal ibrate the surface 

ozone sensors. The MEC-1100 and the ECC-005 instruments obtained outside air 

at new Pol e t hrough t he sampling mani fold . The ECC-002 obtained outside air 

at new Pole through a 5-meter length of Teflon tubing which was fastened to 

the sampl ing manifol d stack but whi ch extended onl y 2 meters above the snow 

surf ace . Duri ng 1975, t he outputs of a ll surface ozone sensors were recorded 

wi th Ru strak st r i p chart r ecorders. 

3.3 . 3 Total Ozone 

The Dobson total ozone spectrophotometer at Pole (serial number 80) performed adequately from turnover until mid- November 1975 . The only persistent 

probl em was t hat the r esults of the instrument ' s monthl y mercury lamp tests 

o f ten perched close to 0.40, the point at which revisi ons to the instrument ' s 

"Tabl e of Settings of Q" a r e required. 

16 
3.3.4 Condensation Nuclei 

The continuous General Electric Condensation Nucleus Counter (serial 

number 7007) was extensively modified in February 1975 according to an electroni c design deve l oped by the Uni versity of Washington under contract to 

GMCC . The modification significantl y improved the instrument's threshold 

of detection and stability. Continuous monitoring proceeded nearly uninterrupted from late March 1975 to the end of the year despite continued deterioration of an optical coupler which had been utilized in the electronic redesign and despite some zero drift problems. The GE counter obtained samples 

of outside air through the sampling manifold. A Pollak nucleus counter 

(serial number 15) was operated at new Pole from mid-January through December. 

During t his period , gaps in the series of measurements were occasioned only 

by preventive maintenance and by repairs to the instrument and its associated 

plumbing. Two series of Pollak measurements were made per day . The first 

coincided with the daily NOAA/NWS balloon launch , and the second started not 

l ess than six hours later. Each seri es consisted of five separate sampl es of 

outside a ir, the first , second , and fifth of which passed only through the 

sampling manifold. The third and fourth samples of each series passed 

through a "diffuser-denuder" after having passed through the manifold . 

In mid-January , a long-tube Gardner condensation nucl eus counter was 

r eceived from Mauna Loa Observatory. Although the long-tube improved the 

detection limits, the Gardner counter still l acked the sensitivity needed for 

austral winter monitoring at Pole when condensation nuc l eus concentration 

would frequently fall below 30 n/cc . ·This was evi dent by the negative meter 

deflections that were consistentl y obtained. 

3.3 . 5 . Sol ar Radiation 

At new Pole , the radiometers listed in Table 4 were all mounted atop a 

wooden platform l ocat ed approximately 15 meters grid southeast of the "c l ean 

air" facility. A multichannel radiometer which arrived at Pole from Boulder 

in mid-January (a thirteen-channel pyrheliometer, serial numbe r 4757 , manufactured by The Eppley Laboratory, Inc.) was mounted on a pedestal approximately 15 meters grid north of the "clean air" facility . 

Soon after the out door install ation of the multichannel radiometer in 

late January, a f luid condensed on the inside face of its viewi ng window. 

The radiometer was cleaned and purged with dry nitrogen but the condensate 

reappeared shortly after. It was discovered that the fluid wa s an oil-based 

substance in the viewing window' s gasket . The gasket was replaced with an 

RTV seal. A few days later, the hub of a gear in the drive train of the 

radiometer ' s solar tracker fractured . Unfortunately , this failure occurred 

when it was too late to obtain a repl acement gear from the United States and 

when the machine t ools necessary to repair the fractured gear had a lready 

been removed from o l d Pol e but not installed at new Pole . 

In mid-March 1975 all GMCC radiometers were removed from their outdoor 

mounts and stored i n the buildi ng. In mi d-October all GMCC radiometers were 

reinstalled outdoors. The multichannel radiometer ' s repaired solar tracker 

17 
Table 4 . Radiometers Used By The GMCC Program at Pole 

Radiometer Type 

Precision Spectral 

Pyranometer, Mod el 2 

II 

II 

II 

Ultraviol et Radiometer (pyranometer) 

No rmal Incidence 

Pyrhe liometer 

Serial No. 

12268F3 

1 2269F3 

12270F3 

12271F3 

1 2349 

2968 

Filter Spectral Passband 

nm 

GG22 390-2600 

OGl 530-2600 

RG8 690-2600 

QG 290-4000 

UGll 290-380 

Quartz 290-4000 

performed satisfact oril y but oil-based crystals again formed on t he inside 

face of the radiometer ' s viewing window. By the end of 1975 , the multichann e l radiometer had still not functioned adequatel y at Pole. However, all 

other radiometers were operational by mid-October and performed without mish ap until mid-November when the Leeds & Northrup multipoint r ecorder used to 

record the outputs of t h e radiometer!:; failed. 

3 .3. 6 Instrument Control and Data Acqui s ition System (ICDAS) 

The I CDAS served sol ely as an ins trume nt contr o l system from mid -August 

until mid-November 197 5 a nd was not again compl etel y operational until midNov ember when GMCC repl acement personnel arrived on station. These gaps in 

the operation o f the ICDAS were du e to hardware diffi c ult i es, software diff iculties, and a lack of "ha nds-on" experience by the GMCC staff. 

The sensor-ICDAS interface circui try of the 1975 GMCC program was very 

different from the circuitry of the 1974 program. The a ddition o f the multichanne l radiometer to the sol ar radiati on project required additional preampl ifi ers whi ch could not be accommodated by the 1974 circuit r y without 

con s iderabl e modification , and in 1975 o nly the signal s of the radiometers 

required amplification b efore processing whereas in 1974 a ll sensor outputs 

required amplification. Several p roblems with the tape drive and the telet ype remained unsolved in 1975 . The ICDAS at Amundsen-Scott was modified in 

December 1975 so that the hardwar e conformed to that at a ll oth er observatories . The modification included replacing the original display c lock and 

a dding a new multipl exer access to the system. The s i ze of the core memory 

in the mi nicomputer was also increased f r om 8k to 16k bytes. Thu s , the 

latest versi on of the execu t i ve program, BOSS-75345, could be accommodated. 

Sen sor s to measure atmospheric pressure and tempe rature (s umme r onl y , O to 

-55°C ) were added and translators for the wind measureme nts we r e inst alled in 

December. 

18 
3.4 Samoa 

Gas sampling and me t eor ological me a s urements begun in 1973 continued 

through 1975. The lack of commercial power during this period necessitated 

the use of portabl e batte ry or spring powered instruments. Wind speed and 

direction, air temperature , and rainfall were measured on Point Matatula. 

Relative humidity, air t emperature , and barometric pressure were measured on 

Lauagae Ridge. C02 and fluorocarbon flas k samples and condensation nucleus 

measurements were taken in both locations . EPA rain samples and ERDA turbidity measurements were taken at the NWS weather station at the airport in 

Tafuna. 

The observatory building was completed in September, and instrument 

installation continued through the last quarter of 1975. Solar radiation 

sensors and the Dobson spectrophotometer dome were installed on the upper 

observation deck. The URAS co2 sampling line and several meteorological 

sensors wer e attached to the University o f Rhode Island s ampling tower on 

Point Matatula. The ECC and Da sibi o zone ins truments were installed in the 

main building and included a short sampling mast erected on the upper observation deck. The ICDAS was ins talled in January, 1976 . 

Table 5 swnmarizes the Samoa sampling programs. 

Tabl e 5 . 1 975 S umma ry o f Sampling Programs a t S amoa 

Monitoring Programs Instrwnent Sampling Frequency Data Record 

Ga s e s 

Carbon Dioxide Evacuated glass flask !/week Jul y 1973 - present 

Fluor oca rbons Evacuated stainl ess steel !/week Sept 1973 - p r esent 

flask 

Ae r osol s 

Condensation nuclei Gardner counter Discrete June 1973 - present 

Meteor ol os:l'. 

Air temp erature Hygrothermograph Conti nuous June 1973 - pr esent 

Dewpoi nt temperatur e Sling psychromet er Discrete June 1973 - present 

Air pr essure Mi c robarograph Continuous Feb 1974 - pr esent 

Prec ipita tion Rainfall col lector Continuous June 1973 - pr esent 

Wind speed/direc tion MRI automated weather Continuous June 1973 - present 

stati on 

Coof e r ative Pro2r ams 

Pr ecipitation MISCO collector Continuous Aug 1973 - present 

chemistry -EPA 

Turbidity -ERDA/I-IMO Eppley dual wavelength Discrete Aug 1973 - present 

sunphotometer 

NCAR Chemical bubbler system 2/month Oct 1973 - Oec 1974 

19 
3.5 Boulder 

Observing programs conducted in Boulder by the GMCC Laboratory staff not 

only serve to gather selected data, but are useful also for purposes of 

training observers and testing instrumentation. 

3 . 5.1 Total Ozone 

Measurements are made on the roof of RB #3 with Dobson spectrophotometer 

No . 82 . This i s a continuing program that was initiated in Boulder in 1966. 

Observational data are routinely processed and results are sent to the Meteorological Service, Canadian Department of Transport, for publication in "Ozone 

Data for the World". 

3.5.2 Erythemal Irradiance 

This program was initiated in Boulder in May 1975, after similar observations, under sponsorship of the CIAP Program, U.S. Department of Transportation, were terminated at Bismarck, North Dakota, and Tallahassee, Florida. 

Results of the Bismarck and Tallahassee measurements have been summarized in 

a report submitted to the Department of Transportation (Machta et al. , 1975). 

The purpose of the Boulder measurements is to continue investigations, at a 

moderately high altitude station, of the relations governing near ground 

level variations in solar ultraviolet radiation that causes sunburn and skin 

cancer with changes in atmospheric total ozone amount. An additional measurement goal is to compare observed erythemal ultraviolet (UV) irradiance 

values with results deduced theoretically for the Boulder location. 

3.5.3 Solar Radiation 

Partially in support of the erythemal irradiance measurements program, 

observations were conducted in Boulder during September 4 to October 30, 

1975, with a quartz global pyranometer (Serial No. 12276) and with a broadband UV radiometer (Serial No. 12350). 

3.5.4 Atmospheric Turbidity 

Measurements of atmospheric turbidity with an EPA dual wavelength sun 

photometer began in Boulder in August 1975, and are continuing on a rou.tine 

operational basis. 

3.5.5 Surface Ozone 

A program to measure surface ozone was initiated at Fritz Peak Observatory in the mountains near Boulder in April 1975. Data obtained at this 

relatively clean-air mid-latitude continental location will be compared with 

20 
data gathered at the GMCC stations. The ozone data are, furthermore, used by 

the NOAA/ERL Aeronomy Laboratory staff in their interpretation of N02 measurements made at the Observatory. 

The measurements were made with an ECC (Electrochemical Concentration 

Ce ll) ozone meter. Comparison observations were obtained during most of the 

time with a photometric Dasibi ozone meter. 

21 
4. GMCC MEASUREMENT PROGRAMS 

This section provides both qualitative and quantitative information on 

individual measurement systems, and presents representative data collected 

and analyzed during the year. 

4.1 Measurement of Gases 

4 . 1.l Carlx>n Dioxide 

Comparison of GMCC ' s URAS-2 continuous analyzer (Serial No . 37626682) 

and Scripps Institution's Applied Physics Analyzer continued at Mauna Loa 

during 1975. Collecti on of data with lx>th instruments, which began in June 

of 1974, will continue until the data have been sati sfactoril y correlated . A 

lightning strike in December disabled the URAS-2 analyzer for one month, but 

the Applied Physics Analyzer was not affected. 

A URAS-2T instrument (Serial No. U2T0029) was operated at Amundsen-Scott 

station in the Antarctic for the entire year. Loss of reference gases and a 

downward zero drift in the analyzer troubled the program but good quality 

data were recorded throughout most of the year. The data will be reduced 

during the first half o f 1976. 

In December 1975, a fourth GMCC continuous C02-analyzer was put into 

operation at the Samoa Observatory . It, too, is a URAS 2T (Serial No. 

U2T0029). 

The UNOR-2 C02 analyzer in operation at Barrow since March 1973 developed serious e l ectronic problems and was replaced with another UNOR-2 (Serial 

No. 63168) in August. As a result of this deterioration in instrument performance, the July data are o f poorer quality. 

Table 6 lists the provisonal monthly mean C02 concentrations determined 

from analyzer measurements at Barrow and Mauna Loa for 1975. All values are 

expressed in C02 ppm based on the Scripps Institution of Oceanography Index 

Scale. 

A new method of flask sampling was initiated at several of the GMCC 

stations during 1975. Whereas previously quasi-simultaneous C02 flask pair 

samples were collected manually by an observer , the new technique employs a 

flask sampling apparatus built into the rack of the continuous C02 analyzer 

in use at the station. By activation of a solenoid valve, air that normally 

passes from the air intake line into the analyzer is diverted into the pair 

of glass flasks for simultaneous flushing and filling to an overpressure of 1 

or 2 psi. An advantage of the new sampling method is that the collection of 

identical air samples is assured. Should analyses yield different values for 

a sample pair, then the difference must arise from collection vessel contamination or from the analysis technique. An additional important feature 

of the new sample collection method is that it allows intercomparison of the 

22 
Table 6. Provisional Monthly Mean C02 Concentrations 

1975 Barrow, Alaska MLO, Hawaii 

Jan. 330.23 ppm 324.24 ppm 

Feb. 331.99 325.32 

Mar. 330.37 325.23 

Apr. 330.22 326.05 

May 331.28 326 . 56 

Jun. 328.21 326.00 

Jul. 323.62 325.33 

Aug. 319.54 323.24 

Sept. 320.35 322.06 

Oct. 323.95 322.34 

Nov. 327 .41 323.06 

Dec. 328.98 Missing 

calibration levels of all field station co2 analyzers si nce analysis of all 

sampl es is performed by means of a reference analyzer maintained at the GMCC 

Techniques and Standards Laboratory in Boulder. 

The sampling method described above was initiated at South Pole station 

i n January 1975. Sampling throughout the year was performed at a frequency 

of twice per month. A small fracture in a short length o f air intake line 

inside the observatory building caused room air to leak into the analyzer 

during April to June, resul ting in the collection of contaminated sampl es. 

COz flask sampling was continued at Barrow during all 

new sampling technique described above initiated in June. 

quency was once per week . 

of 1975, with the 

The sampling freHand-aspirated , weekly , C02 flask sampl es were also collected at the 

Samoa Observatory until December 1975 , at which time a change was made to the 

new f l ask sampling method. 

Provisional 1975 mean monthly C02 concentrations for the three stations 

mentioned above are given in Table 7. These flask sampling data are shown 

graphicall y in Figure 10 . 

Through-the-analyzer co2 flask sampling i s planned for Mauna Loa, beginning early in 1976. We expect, furthermore, to resume soon the collection 

of hand-aspirated COz f l ask samples at Niwot Ridge, Colorado, and Key Biscayne, Florida. In addition, a new manual sampling program will be commenced 

at Cape Kumukaki, Hawaii. 

23 
Table 7 . Provisional Mean Monthly C02 Index Values Determined From Flask Sampling in 1975 

South Pole Samoa Barrow 

Mean Mean Mean Month # of Cone. # of Cone. # of Cone . Samples Index (J Samples Index CJ Samples Index CJ 

Jan. 1 323. 77 ----- 4 324.31 1.13 4 331. 51 2.87 

Feb. 2 323 .53 0 . 11 + Msg 4 330 . 26 0 . 96 

Mar. 2 323. 71 0 . 39 3 325.31 0.94 4 329.84 0.42 

Apr. 2 (324.16) 0.46 2 323.69 0.13 2 328.95 2.41 

May 2 (326.38) 1.82 4 325 . 36 1.49 5 330 .17 0.24 

June 2 (328.07) 2 . 23 2 326.45 2 . 96 *5 328 . 56 4.04 

July 2 323.91 0.04 3 325.42 0.70 2 323 . 31 2 . 08 

I\) Aug . 2 324 . 64 0.03 4 327.20 4.45 6 319.51 1.97 .t:> 

Sept. 2 325 . 03 0 . 55 2 325.12 0 . 86 5 320.78 1.56 

Oct. 2 324.67 0.25 2 325.68 6 323.41 0 . 63 

Nov. 2 324.64 ++ Msg 6 327. 31 2.57 

Dec. 2 325.10 1 324.87 ----- 4 332 . 57 4.23 

Data in parentheses affected by air intake line leak. 

+Station closed - Mr. Rumble was in Boulder for the annual meeting. 

++No samples obtained during Nov. and part of Dec . Simultaneous sampling was begun mid-Dec . 

*Simultaneous flask sampling started on 10 June 1975. 
33 

32 

31 

>< 330 Q) 

"D 

c 29 

E 28 Q. 

Q. 

c 27 c 

. Q 26 -0 

"'-

-c 325 Q) 

u 

c 24 0 

u 

c 23 

0 

Q) 22 2 

>. 21 ..c 

c 

0 320 2 

19 

318 

,. '"'-

: / . :'/' 

M '\. • , 

. "' .</ ...._ --v -.....--

So. Pole 90° S 

• · • • • South Pole Doto Affected 

by on Air Intake Line Leak 

M Missing Doto 

2 3 4 5 6 

""Samoa 17° S 

/· 

. \ ./ ·'-·___.. 

...------------ .,.,,.., / 

7 8 9 10 

Figure 10. Flask sampling co2 data, 1975 . 

4.1.2 Total Ozone 

II 12 

The U.S. Dobson spectrophotometer network now comprises thirteen stations where measurements are made of total ozone on a daily basis (Table 8) . 

The last station to be established was that in Samoa. Routine observations began December 19, 1975, at the Samoa GMCC Observatory (Fig. 11) 

located on Tutuila Island , American Samoa (14°15 ' S, 170°34'W). 

In view of the increasing importance of atmospheric ozone research and 

in consideration of the fact that no total ozone observatories are located 

west of the Rocky Mountains, a decision was made earl y in 1975 to move the 

Green Bay, Wisconsin, Dobson station to some western l ocation. Relocation 

of an existing facility rather than establ ishment of a new one is necessary 

since the supply of ozone spectrophotometers is critically low and the instruments are no longer commercial ly available. Furthermore, comparisons of 

25 
Table B. Th e u. S . Dobson Spectrophot ometer Network 

Instr. 

Ser. 

Station Period of Record No. 

Bis marck , N.Dak . 010163- Present 33 

Caribo u, Maine 010163-Present 34 

Gr e en Bay, Wis. 102063-063075 38 

Tutuila I s. , Samoa 1 2 1975- Present 42 

Tallahassee , Fla . 060273-Present 58 

Mauna Loa , Hawaii 010264- Present 63 

Wa llops I s l and , Va . 070167-Present 72 

Barrow , Al aska 080273-Present 76 

Nashville, Tenn. 010163- Present 79 

Amundsen- Scott 1 20563-Present 80 

Boulde r, Col o . 090166-Present 82 

White Sands , N. Mex . 010572-Present 86 

Hua n cayo , Pe ru 021464-Present 87 

Agency 

NOAA-ARL 

NOAA-ARL 

NOAA-ARL 

NOAA-ARL 

F l a. State u. 

NOAA-ARL 

NOAA-ARL 

NOAA-ARL 

NOAA-ARL 

NOAA-ARL 

NOAA-ARL 

Dept. of Army 

NOAA-ARL 

the Green Bay and Toronto , Canada , ozone data for the past decade have indi -

cated that data from either station are representative for the region . Final 

measurements of total ozone were made at Green Bay on June 30 , 1975 . 

The new western l ocation has not yet been chosen a lthough several s ites 

are unde r investigation, particularl y in the Southwest. Since terminating 

the Gr een Bay , Wisconsin , station , we have acquired Dobson spectroph otometer 

No. 9 4 on loan from the Departme nt of Meteorol ogy, Nava l Postgraduate School, 

Monterey , Cal fifornia. This instrument will be us ed at our western s t a tion . 

MODERNIZATION OF IXJBSON SPECTROPHOTOMETERS 

During t he spring of 1975, work was comp l eted on modifying the e l ectronic and e l ectromech ani cal systems of Dobson spectrophotome t er No . 4 2 . All 

Dobson ozon e instruments u sed at station s in the U.S . network , with the excepti on of Huancayo , Peru , now empl oy miniature solid - state , built-in highvoltage converters, modern solid- state amplifier circuitry , and electrome -

c h anical phase- sen s itive r ecti f i e r s . Since the modificati on program began in 

1971 , essen tial ly no data have been l ost because of inoperative instruments . 

Furthermore , probl ems experienced in the past, such as l ow instrume nt sensit i vity and l ow s i gnal-to noise ratio , have been v irtua lly e liminated. 

Wo rk has a l so begun in replacing ori ginal Dobson spectrophotometer 

shutter motors and drive assemblies of English manu fac ture with mo r e r e adily 

26 
Figure 11. Samoa GMCC Observatory. 

procurable components made in the U. S . The new assemblies employ nylon belt 

rather than fri ction pulley drives, and sync~ronous 1800-rpm motors with a 

torque of 0 . 6 inch-ounce. To date , motor and drive assemblies have been 

modified in the Boul der, Caribou, Nashville, Samoa , and White Sands instrume nts . 

CALIBRATIONS 

In 1972 a program was initiated to calibrate each Dobson instrument in 

the U.S. network every two or three years. In accordance with this plan, the 

Nashville , Caribou , Boulder, and Samoa spectrophotometers were recalibrated 

at Boulder, Colorado , during 1975. 

In order to improve the quality of the total ozone data at the Nashvill e 

and Caribou stati ons, students were hired to take special observations during 

June, Jul y, and August of 1975 . These special observations were of three 

types: 

27 
a. Quasi-simul taneous observations of vari ous t ypes 

b. Observations for cal ibrating spectrophotometers on an Absolute 

Scale 

c. Zenith sky observati ons using t he HNP linear polarizer 

All observati ons b y the students were made between sunrise and local 

apparent noon as Mu (a quantity rel a ted to air mass) varied f r om 3.50 to 

approximately 1.10 . On s ome days as many as 60 obser vati o ns were made. 

Analysis of the data is i n progr ess. 

DATA 

Figure 12 shows plots of the mean mo n thly total .ozone amounts determined 

at the s tation s in the U.S. network during 1975. The vertical bars in the 

plots are standard deviations associated with the means and represent natural 

variability in the data as well as observer a nd instrume nt e rrors. The 

Nashville, Caribou, and Amundsen-Scott data for 1975 h ave been designated 

"provisional " because final corrections to the data have yet to be appl ied. 

400 

E 

u 

0 300 

IONAL 

CARIBOU, ME.(46°52'N) 

E '-------------' 

<l 500- ------------, ~ 

::? 400 

Q) 

c 

0 300 0 

0 500--------- -~ 

~ 

300 GREE N 

~ BAY, Wl.(44°29'Nl 

400 -

400 

300 -

WALLOPS IS., VA.(37°51'Nl 

400 

300 

400 - NASHVILLE, TN. (36°15'N) PROVISIONAL 

300 - ~ 

500 - WHITE SANDS, N.M. (32°23'N) 

400 -

300 

400 TALLAHASSEE, FL. (30°26'N) 

300 

400----

~ 

------- -, 

- MAUNA LOA, HI. (19°32'NJ 

300 

300 BARROW, AK.(71°19'N) 

400 I 

- HUANCAYO, PERU (12°3'Sl 

300 

200 I 

400 

SAMOA, TUTUILA IS. (14° 15'S l 

300 -

200 ' I 

400 _ AMUNDSEN-SCOTT, ANTARCTICA 

300 (90"S)l PROVISIONAL 

- 00'----J-F_M _J_J_A_S_O~N~D 00 L----'--J....___,,..._,..,--,..A~.,_....,J--;--;--~-:::-~ 

1975 1975 

Figure 12 . Mean monthl y total ozone with standard deviations for t h e U. S . 

Dobson ozone spectrophotometer network , 1975 . 

28 
4.1.3 Surface Ozone 

This year marked completion of the deployment of updated electrochemical 

concentration cell (ECC) ozone meters (see Summary Report No. 1 for a description of the meters' principle of operation) to all four GMCC observatories. In addition, an ultraviolet absorption ozone photometer (Dasibi), 

described later in this secti on , was installed at each of the observatories. 

At the South Pole, measurements were continued using the chemiluminescent 

ozone analyzer. 

Surface oxidant measurements were continued at Boulder and a new observing si te was established at the Fritz Peak Observatory in the mountains west 

of Boulder. In addition to providing a nearby site for making routine measurements in air that is considerably less contaminated than that at Boul der, 

the Fritz Peak location is being used for instrument testing and calibration. 

DATA PROCESSING AND ARCHIVING 

During 1975 procedures were worked out with the Canadian Department of 

the Environment, the agency responsible for publ ishing atmospheric ozone data 

under an agreement with the World Meteorological Organization , for publication of surface ozone data from the GMCC network. Data published will be 

dail y means, maxima, and minima, as well as the monthly averages of these 

quantities. The data indicated as archived i n Table 9 have been submitted to 

Canada for publication in the format illustrated in Figure 13. They will be 

avail able from the Canadian agency at a nominal cost. 

The larger set of data consist of hourly average surface ozone parti al 

pressures for the four GMCC locations and for the auxilli ary stations at 

Boulder and Fritz Peak, and data gathered prior to 1973. All data are contained on magnetic tape or punch cards and on microfilm at Boulder. 

DATA SUMMARY 

The use of both an ECC and a chemiluminescent or Dasibi-type ozone analyzer at the GMCC locations provides a redundancy in the measuring systems . 

The primary feature desired in an ozone measuring system is t he ability to 

make measurements on an absolute scale at t he 0generally low ozone concentrations found in clean tropospheric air at the GMCC observatories. The need 

for absolute measurements has become increasingly apparent in light of difficulties experienced in calibrating and maintaining a secondary ozone standard. 

The ECC ozone meter was chosen for use initially because of its ability 

to measure ozone on an absolute scale, its availability at minimal cost, and 

previous experience with its operati on. Concern was expressed about this 

instrument because of possible interferences by other gases and the somewhat 

slow (20-second exponential) response. Neither of these concerns was justified , however, because interfering gases appear to exist at very l ow concentrations at the GMCC baseline locations , and ozone changes take place on the 

scale of hours or even days so that the response of the meter is more t han 

adequate . A more persistent problem in operating the ECC meter has been sensing solution integrity . Inadvertent introduction of oxidants or reductants 

29 
Table 9. Status of Processing and Archiving of Surface Ozone Data 

STATION PROCESSED ARCHIVED 

BARROW 

ECC Mar 73 Dec 75 Mar 73 - Dec 75 

Dasibi Jul 75 Dec 75 ------

MAUN A LOA 

ECC Aug 73 Dec 75 Aug 73 - Dec 75 

Dasibi Sep 75 Dec 75 ------

SAMOA 

None None 

SOUTH POLE 

ECC Jan 75 Dec 75 ------

MEC Chemilu Mar 74 Dec 75 Mar 74 - Dec 75 

BOULDER 

ECC May 73 - Dec 75 

FRITZ PEAK 

ECC Apr 75 Dec 75 

Dasibi Apr 75 Dec 75 

SURFACE OZONE HEASURE•ENTS FROH SELECTED STATIONS 

················································· DATE l 6 8 9 10 ll 12 13 l• 15 16 17 18 19 20 21 22 23 2 • 2S 26 27 28 29 30 31 

BAAAOVt AlASfl'A FEBRUARY 1974 

HEAN 25 28 JI 21 26 3 1 25 22 23 2• 16 l• 26 25 24 29 28 

MAX 27 30 32 30 30 3• 26 2• 27 26 18 19 30 J O 31 37 31 

HH 16 20 15 Ol 23 20 06 l7 18 07 OJ 12 22 I• l7 18 03 

MIN 23 Z2 30 22 2• 29 20 l7 19 21 l• 7 17 14 12 2J 2• 

ElTREHES I MAX 37, HIN 7. HONTHL Y MEANS I "EAN zs, MAX 280 HIN 20 ,EOUIPHNT ECC 

BAAAOVt ALASKA APRIL 1974 

HEAN IJ • 21 19 27 

MA X 18 20 30 33 J5 

HM OJ 23 22 23 03 

HIN 6 I 15 5 19 

EXTREMES I HU 35 , HIN l. MONTHLY MEANSI MEAN 17t MAX 27 • MIN 9 ,EQUIPMENT [CC 

BAAAOtilt ALA.SICA HAY 1914 

MEAN 28 20 35 JO 19 26 9 • 5 6 6 18 20 15 l• 18 18 26 27 30 15 2J J3 29 26 22 20 2J 28 26 24 

MAX 37 J4 •o J6 26 28 21 10 8 9 lS 2J 2• 18 16 21 22 JO 3• 3J 2• J9 37 J• 29 29 27 28 JI 29 29 

HH OJ Z3 16 01 19 08 oo 06 07 20 2J l 0 10 02 23 20 01 08 16 15 00 16 2 1 18 01 00 01 20 17 22 13 

HIN 20 lJ J2 24 IJ 22 l I l l I 15 15 12 12 15 16 20 19 22 ll 9 27 20 21 17 I• 15 25 24 20 

EXTAEMCS I lifAI 40 , HI N l. lilOHTHL Y Hf ANS I ME AN 21 t HAA 26. HIN 15.EOUIPHENT ECC 

8ARAO'W t ALASICA JUNE t•H• MEAN 18 19 l • l l 16 IJ l• 16 22 8 l 16 2J 13 l • 12 16 25 2 • 21 27 26 l l 20 28 29 29 J O 26 ZJ MA X 20 28 17 19 20 29 JJ l l 25 14 I• 21 J• 15 16 16 21 34 28 23 29 28 Z2 2• JJ 34 3• 33 28 25 

HH 20 05 18 2J 08 22 02 IJ 12 00 2J 2J o• 06 21 22 18 12 02 22 16 16 00 II 22 23 01 18 19 19 

HIN I I 9 9 15 lJ 9 5 10 15 5 • IJ II 10 ll 9 12 15 II 18 22 2 • 12 13 20 26 22 27 2• 21 

El TRO•CS I "''I J4, HIN .. MONTHLY MEANS: MEAN }9t JiiAX 2•· MJN 14 , EQUIPMENT ECC 

BAAPOV, ALASKA JULY 1974 

HEAN 22 21 25 15 l• IS 15 I• IS .. II lJ 14 Io .. 16 19 18 19 ll 10. " 16 14 MAX 25 25 J> ·~ 16 19 18 12 14 .. 22 23 25 ,. ~ 22 HH 18 >J 00 

Figure 13. Format of GMCC data published by the Canadian Department of the 

Environment. 

30 
into the sensing solution produces noisy signals and raises uncertainties in 

the absolute amount of ozone r ecorded . 

The first attempt at ozone measurements with a second instrument used 

the chemiluminescent analyzer described in Summary Report No . 3 . Such instruments are known to be relatively free of interferences, are fast r espondi ng, 

and do not require the u se of liquids. They do , however , requir e the use of 

ethylene gas , and do not measure ozone on an absolute scal e. A chemiluminescent ozone a nalyzer was used at South Pol e in 1974 and 1975. ECC meters were 

also used there . However, the ECC meter operated at South Pol e in 1974 was 

subject to gross sensing solution contaminati on and produced few useful data. 

The chemiluminescent analyzer at South Pole , on the other hand, was subject to thermal drift and there is an uncertainty in the absolute values assigned to the data. The ozone generators used as secondary standards were 

not as stable a s had been anticipated , and were found later to r equire extensive modifications. 

Figure 14 shows the hourly average surface ozone amounts obtained during 

November and December 1975 when both the ECC and chemiluminescent analyzers 

appeared to be working well. Figure 15 shows the mean monthly values for 

1975 as r ecorded by the two analyzers. There is a signifi cant difference in 

30 

f~~ 

Nov. 1975 ~ 

~ 

ECC 

~'vNV .S 10 Cl) 

..... MEC CHEMILU :3 

I/) 

I/) Dec.1975 £ 30 

~ 

~ ..... 

Cl) 

v--~~ c 

0 

0 

20 

10 

ECC 

Oec.1975 

10 

~ MEC CHEMILU 

5 10 15 20 25 30 

Doy 

Figure 14. Hourl y surface ozone at 

Sou th Pole for two months. 

31 

I/) 

..... 

0 

.0 

0 

c 

0 

z 

c 

~ :3 

I/) 

I/) 

~ 

a.. 

~ 

& 

Cl) 

§ 

N 

0 

20 

10 

10 

ECC 

MEC CHEMILU 

JF MAM JJ A SO ND 

Month 

Figure 15. Mean monthly s urface 

ozone at South Pole in 1975. 
the trend of the monthly mean results near the end of the period (November 

and December) even though both instruments appeared to be respond similarly 

to the day-to-day variations. 

The monthly mean surface ozone data for all of the observing locations 

are plotted in Figure 16 for the period 1973-1975. 

CALIBRATIONS 

With the introduction of the Dasibi ozone photometer into the surface 

ozone network , it was discovered that the McMillan Electronics Corporation 

(MEC) Model 1000 ozone generator was inadequate as a secondary calibrat ion 

standard because of defects in its desi gn. A major defect was the use of 

ozone-destroying material s in the construction of the generator's air flow 

system , which rendered the unit incapable of providing a stable source of 

ozone over an extended time period. Because of inadequate filtering of incoming air, the generator was also found to be a source of particulates which 

interfered when the reference gas from the generator was sampled by a Dasibi 

ozone meter. 

Our MEC ozone generators have been extensivel y modified recently to 

overcome the d efects described above , and now appear to work satisfactorily 

as secondary ozone standards. A block diagram of a modified generator is 

shown in Figure 17, the major modification being incorporation into the instrument of a doubl e quartz tube reaction chamber in which ozone i s produced 

photometrically without parti al destruction by wall effects. 

40 Borrow (71 °N) 

20 ~-,, 

"' 

ECC .... 

0 40 Boulder (40°N) .D 

0 

c: 

0 

z 20 

.!: 

~ ::J 40 Fritzpeok (40°N) "' "' Cll 

.... 

0.. 20 0 

:;: ECC .... 

0 

0.. 30 Mouno Loo (20°N) 

Cll 

c: 

0 

N 10 

0 ECC 

Figure 16. Monthly surface ozone. 30 South Pole (90°S) 

10 

J J IJ J 

1973 1975 

32 
Generators calibrated against ECC Ozone Meter Model 001 , Serial No. 001, 

have been deployed to each GMCC location for use in checks every 2 weeks on 

the performance of both the ECC Ozone Meter Model 005 and Dasibi ozone photometer. 

A remaining probl em in using MEC generators as accurate secondary standards concerns the development of corrections for changes in generator output 

due to changes in atmospheric pressure. The generators are normally cali -

brated at one pressure but are used at a far different pressure--that prevailing at t he observing station. To date , the pressure corrections have been 

determined by measuring the ozone output of the generators at Boulder (average pressure 834 mb) and at Fritz Peak Observatory (average pressure 730 rnb) , 

and extrapol ating the results to the pressure of the observatory where the 

generator is to be used. A preferable procedure would involve the use of an 

environmental test chamber where the ozone ouptut of the generator could be 

measured at the appropriate pressure. Such a chamber has been purchased but 

was not available for use during 1975. 

INSTRUMENTATION 

The ultraviolet absorption ozone photometer was added to the inventory 

of analyzers making sur face ozone measurements at the GMCC locations. This 

instrument , manufactured by the Dasibi Environmental Corporation of Glendal e , 

California , will be used alongside the ECC Model 005 meter at all of the GMCC 

locations. I t will replace the chemiluminescent analyzer at the South Pole 

Observatory. 

The design of the Dasibi ozone photometer is based on the absorption of 

253.7-nm wavelength light by ozone. The photometer comprises a monochromatic 

UV source , a sample chamber , a UV detector, and a signal processing and 

readout system. Two reference subsystems provide stability by correcting for 

source intensity , optical path transmittance, and detector response changes. 

Inlet Air Filler and Ozone Destructor 

Diaphragm Pump 

Pressure Gage 

l ,ooe G•oornt;og 

Chamber 

r 1/4 Tube Size 

Exhaust Port 

1/811 Tube Size 

Sample Ports 

\__ Ozonized Air 

Teflon Coated 

Sample Manifold 

33 

Figure 17. Diagram of the 

McMillan ozone generator 

(modified) . 
The block diagram of Figure 18 i l lustrates operat i on of the i nstrument . 

After entering the instr ument the sample is diver ted by means of a gas valve 

i nto the selective gas filter in which the active catal yst (manganese d i oxide) converts all ozone to oxygen. The ozone- free a i r sampl e then passes 

through the absorpti on chamber where a detector measures the amount o f ultrav i ol et light transmitted thr ough it. This inf or mation is then stored d igi -

tally in the instrument to serve as a reference mea sur ement since it r epr e -

sent s absorption by trace substances other t han ozone pr esent in the air. 

Upon completion of t his measurement, the gas val ve is acti vated t o a l l ow 

ambient air to enter t he photometer ' s absorpti on chambe r. The amount o f 

ul traviolet l ight, now reduced because of the pres ence o f ozone , i s again 

detected and stored d i gital ly. The first measurement i s then subtrac ted from 

the second to yield to the corrected ambient ozone background value . 

The basic equation appl icable to the Dasibi ozone photometer i s : 

I (1) 

where Io is the initial intensity of the 253 . 7-nm light gi ven of f by the 

ultraviolet lamp , I is the final intensity, oA i s the ozone absorpti on cross 

section for the wavel ength A= 253.7 nm, n3 is t he number of ozone mol ecul es 

i n the path length, and t is the path length (71 cm). Digital readout on the 

instrument is provided in units of ozone mixing ratio (parts per million by 

vol ume) applicabl e to standard (0°C, 1 atmospher e pr essure) operati ng condi -

tions. Ozone amounts in units of ozone partial pr essur e at ambient pr essure 

and temperature conditions can be computed from 

4 OUTPUT P3 (nb) = 172 •T• log [ 1-10 • ] e SPAN ( 2) 

where T is the operating temperature of the instrument in degrees Kelvin , 

OUTPUT is the digital display readout , and SPAN is a digi tal count pr opor -

tional ~o Io in equati on (1) that allows scaling o f the OUTPUT . SPAN is 

Detector 111 Digital Electrometer 111 Integrator Discriminator 

X Window t y Win dow 

Mercury ~1 Absorption Chamber 'I 

Light Source -.......,.,.--------. Di ital Electrometer II 

Exhaust Pump "'- Reversible lnte rator ...,.. ___ _ 

Exhaust Start Positive Integration Data 

Sta Output rt Negative Integration 

Gas Sample Inlet 

Figure 18. Diagram of the Dasibi ozone monitor. 

34 

...., 

n> 

... 

V'I 

n> ....,_ 

-· = -= -

n> 

~ 

~ 

c;· 

= 
normally set at a value of 520,000 counts so that the display then reads out 

the approximate ozone amount directly in partial pressure, although in the 

somewhat unwieldy units of 103 nanobars (1 microbar) . 

4.1.4 Halocarbons 

PROGRAM 

Although the project leader for the GMCC Freon-11 program relocated to 

the Techniques and Standards Group in 1974, actual flask preparation and 

analyses were continued at the Air Resources Laboratory's Field Research 

Office at Idaho Falls, Idaho, until the middle of May 1975. Sampling continued at Barrow, Mauna Loa, and Samoa wi th stainless steel flasks. Outlined 

below are the operating conditions of the Electron Capture Chromatograph used 

at Idaho Falls to analyze the flask samples: 

Detector: 

Detector Temperature: 

Column: 

Column Temperature: 

Carrier Gas: 

Flow Rate: 

Electronics: 

Pulse width : 

Pulse period: 

Pulse height: 

Samp l e Volume: 

15 milicuries Nickel 63 

30°C 

lO'x~" Carbowax 400/Porasil F 

30°C 

Ultra-pure nitrogen 

50 cc/min 

Fixed pulse mode 

2 microseconds 

200 microseconds 

-20 volts 

5 cc 

A Hewlett-Packard variable frequency gas chromatograph was received in 

April 1975 and put into operation at the Techniques and Standards Laboratory 

in Boulder, Colorado. The operating conditions of this instrument were: 

Detector: 

Detector Temperature: 

Column: 

Column Temperature: 

Carrier Gas: 

Flow Rate: 

El ectronics: 

Sampl e Volume: 

15 millicuries Nickel 63 

100°C 

lO'xl/8" Carbowax 400/Porasil F 

40°C 

95% Argon--5% Methane 

15 cc/min 

Variabl e frequency mode 

1 cc 

Transfer of the compl ete halocarbon program took place in mid-May and 

the stations were instructed to send all exposed flasks to Boulder for analysis. Cross comparisons were made of the Idaho Falls system and Boulder 

system by analysis of the same samples at both locations. 

As f l asks were analyzed in Boulder, i t became apparent that the sensitivity of the Hewlett-Packard chromatograph was too low because of certain 

limiting design features. For partial correction of this deficiency, the 

Idaho Falls detector and electronics were transferred to Boulder. A duplicate of the electronics was fabricated and, together with the detector, was 

35 
installed in the Hewlett-Packard chromatograph to continue the analysis. 

This configuration was used through the remainder of the year. The operating 

conditions were : 

Detector: 

Detector Temperature: 

Column: 

Column Temperature: 

Carrier Gas : 

Flow Rate: 

Electronics: 

Pulse width: 

Pulse period: 

Pulse height: 

Sample Volume: 

15 millicuries Ni ckel 63 

150°C 

lO ' xl/8" Carbowax 400/Porasil C 

70°C 

Ultra- pure nitrogen 

20 cc/min. 

Fixed pulse mode 

2 microseconds 

200 microseconds 

-20 volts 

1 cc 

Tests on the Hewlett-Packard chromatograph were continued to determine 

whether the sensitivity of the instrument could be increased under variable 

frequency operating mode. The manufacturer has recommended certain electronic modifications to the instrument which will be attempted in 1976 . 

INSTRUMENT DEVELOPMENT 

A. Gas Dilution Apparatus 

The Idaho Falls chromatograph system was initially calibraled for 

Freon-11 on the basis of coul ometry and this calibration was transferred 

to Boul der by sample comparisons. A number of errors can arise using 

such an approach. Implementation of an independent calibration gas 

method was, therefore , considered . 

Because of simplicity of design, a static gas dilution system was 

built. In the design stage, the virial coeffi cient gas l aw was used and 

an error analysis made using manufacturer ' s commonly quoted accuracies 

and precisions for temperature and pressure measurements. A schematic 

diagram o f this system is shown in Figure 19. 

The operational procedure is for pure Freon-11 (sample) gas to be 

introduced into an evacuated volume of approximately 10 cc where the gas 

is isolated and its temperature and pressure measured . The small gas 

volume is now expanded into a large volume of 10, 000 cc and a dilution 

gas introduced. Temperature and pressure are again measured. With the 

resulting 1000:1 volume ratio and a 10:1 pressure ratio, a dilution of 

104 is possible. If the mixture is then reintroduced into the smaller 

volume and the large volume again evacuated , the procedure can be repeated again and again to reach any desired sample gas concentration. 

During December several attempts were made to achieve a three- stage 

dilution into the parts-per-trillion range using fluorocarbon-11 and 

nitrogen. Successive batches of the gas mixtures did not show repeatability, probably because of container wall effects. Further tests are 

in progress. 

36 
Dilution Gos IN----. 

Pressure 

Capacitance 

Manometer " \ 

Small Volume IOcc 

Lorge Volume 10000 cc 

\ / 

\ // 

I I / I/ _.,..,./ 

I/ -- // 

/ ---- Sample Gos ,;/' -- -"//-"/. --

DATA 

/// 

ci 

Dilution Gos IN 

Temperature Vacuum 

Thermocouple 

Figure 19. Diagram of gas dilution apparatus. 

8 . Cylinder Pump-Up System 

A preponderance of apparently contaminated (hi gh-reading) fluorocarbon-11 samples collected at the GMCC field stations during 1975 indicated the need for an improved sampling technique. To eliminate problems inherent in sampling with stainless steel flasks , a decision was 

made to coll ect air samples pressurized to an overpressure of about 10 

psi above ambient air pressure. A prototype flask pump-up apparatus, 

shown in Figure 20, was therefore built and tested. First field use of 

the unit will be at South Pole Station in January 1976. 

Table 10 lists the halocarbon-11 (CCl3F) concentrations determined from 

f l ask air samples collected at the GMCC baseline stations. Indicated standard deviati ons were determined from the spread in repeated sampl e anal yses. 

The overall uncertainty in the concentrations is estimated to be ±25% except 

for data obtained during October, November , and December 1975 in which flask 

contamination may have caused the unexpectedly high concentrations. The 

problem is under investigation. 

37 
Table 10. 1975 Data Base CCl3F 

BARROW SAMOA MAUNA LOA 

F-11 Cone. F-11 Cone . F-11 Cone. 

Month Day (ppt) 0 Day (ppt) 0 Day (ppt) 0 

Jan 16 120 5 4 1 55 7 3 142 4 

28 137 7 14 164 21- 10 149 13 

21 94 1 44 17 118 14 

31 170 21 

Feb 11 143 13 3 113 8 

18 136 4 7 161 6 

26 112 15 19 114 7 

26 14628 221 

Mar 4 108 2 13 92 10 5 97 3 

14 111 4 21 99 10 12 110 6 

18 102 2 31 106 7 19 115 4 

25 149 7 25 107 9 

Apr l 142 3 10 116 4 9 10 5 3 

15 99 8 18 145 10 16 1836 21 

25 114 7 23 99 4 

28 98 2 

May l 119 3 6 5153 2 114 5 

9 102 4 12 64 6 7 105 4 

13 155 3 20 108 8 13 100 7 

20 168 7 17 95 7 

27 95 6 21 82 10 

29 106 16 

Jun 5 103 4 8 109 6 7 134 10 

10 106 5 8 83 5 12 85 10 

21 85 5 

Jul 15 147 9 12 781 13 l 776 24 

25 107 6 

Aug 3 117 15 l 260 7 8 185 22 

14 105 7 14 598 6 14 106 18 

22 233 9 21 278 20 

27 320 11 

Sep 6 132 8 6 220 9 5 185 16 

16 203 6 13 681 16 11 225 31 

26 220 9 18 243 4 

25 30353 

Oct l 128 8 2 503 7 2 147 7 

10 540 10 10 220 11 9 346 12 

14 231 5 18 415 12 16 371 21 

23 202 11 31 307 3 24 331 5 

Nov 12 272 6 8 284 1 6 370 8 

19 132 5 

Dec 16 204 8 14 256 2 

24 948 6 

30 251 7 

38 
Connector 

Sample 

Cylinders 

Filler 

Pressure Gouge 

D 

Bel lows Pump 

Relief Valve 

Shutoff Valve 

Figure 20. Diagram of cylinder pump-up system. 

The 1975 data and all previously obtained data are graphically displayed 

in Figures 21, 22, and 23. 

In a cooperative effort with Naval Research Laboratory, 18 stainless 

steel flask air samples were collected during Arctic flights in April and May 

1975. CCl3F analysis results for these samples are shown in Table 11. 

4.2 Upper-Air Measurements Using Lidar 

4.2.1 Aerosols 

A major activity during 1975 was the continuing study of the enhanced 

stratospheric dust layer caused by the eruption of Fuego volcano in Guatemala 

during October 1974 (Fegley & Ellis, 1975) Observations were made during the 

evening hours, one day per week. Although this event was less significant in 

terms of stratospheric enhancement than the Agung volcano eruption during the 

39 
-a. 

a. 

c 

0 

+;: 

~ 

c 

'11 

u 

c 

0 

:..J 

450 -1 

400 

350 

300 

250 

200 

150 

100 

50 

t. I • 

I 

I I 

•• 

+ • 

I • 

+ + , I 

t t r If• 1• 

•• I '"· t• 1" 

I 

I ' 

• I 

I I + I I 

0 S 0 N 0 J F M A1 M J J A S 0 N 0 J FM AM J J AS 0 N 0 

1973 1974 1975 

500 

450 

400 

350 

300 

250 

'1 

200 

I ~I . • ,,JI 150 If d'. I 

100 ,11' I I 

• + I t 1+ I J• >• 

50 

O S 0

1 

N D J F M A M J J A S 0 N 0 J F M A M J J A S O N O 

19 73 1974 1975 

5oo ITITlllllTl~~rr.-11-.---r-r---r-.,.......,.--r---,--,~ 

450 

400 

350 

300 

250 

200 

150 

100 

50 

• ~I •• + .. 

OSONOJFMAMJJ 

!

+. I I ..... ~ I 

• 11 ·t··~,1, 

I 

I 

r 

f I 

A SONO JF MAMJ JASONO 

1973 1974 197 5 

40 

Figur e 21. CCl3F data 

for Barrow, Alaska. 

Figure 22 . CCl3F data 

for Cape Ma ta tula , Samoa. 

Figure 23. Ccl 3F data 

for Mauna Loa , Hawaii. 
Table 11. CCl3F Values from NRL Cooperative Program 

Date Sampl e Altitude F-11 Cone . Position 

1975 No. (feet) (ppt) 

4-17 2 1000 llO. 2 85°46 ' N 40°00 ' W 

17 4 1000 103.5 84°39 ' N 67O 12 I W 

18 6 1000 90.2 85°48 ' N 20°49 ' W 

18 8 1000 970. 8 85°25 ' N 40°33 'W 

1 9 10 1000 107 . 5 85°29'N 25°26'W 

21 12 1000 94 .1 85°09 ' N 24 ° 39 'w 

23 14 1000 105.4 81°39'N 61°57 ' W 

28 19 1000 108. 9 82°55 ' N 58°46 ' W 

29 22 1000 98. 5 87°14 ' N 25°28 ' W 

5- 1 25 1000 131.l 87°25 ' N 27°42 ' W 

2 27 22000 86.3 82°37 ' N 56°55 ' W 

2 29 1000 113. 2 86°07 ' N 77°58 ' W 

2 31 27000 78.9 86°10 'N 44°52 ' W 

3 33 1000 111.6 86°ll ' N 87°03 ' W 

5 35 1500 111.6 84°03 'N 48°03 ' W 

5 37 20000 101. 9 89°29 ' N 28°22 ' W 

5 39 20000 6 1. 3 87°46 'N 18°44 ' E 

5 41 1000 116.9 82°56 ' N 20°08 ' E 

mid-1960 ' s , i t remai ns one of the better studied events by the use of advanced monitoring systems such as lidar and stratospheric research vehicles 

(Rosen et al., 1975 ; Elterman , 1975). 

Figure 24 summarizes the 1975 study of the Fuego event. It is a plot of 

the integral of the backscatter coefficient throughout the depth of the 

stratospheri c c loud. Weekl y values are shown rather than monthly averages. 

The dust l ayer first appeared at Mauna Loa on October 8, 1974 , as a clearly 

defined layer slightl y above the tropopause . Its intensity increased such 

that by November 5 the l ayer was e a sil y v i sible to the eye as a widespread 

cirrus-like layer. As the layer continued to diffuse both hori zontall y and 

vertically, i t became less prominent. (Originally the layer was less than 1 

km thick but gradually thi ckened to 3 to 4 km toward mid-1975.) The layer 

was much more horizontally uniform after about March 1975 and generally weakened until finally resembling the normal Junge layer of late 1973 . During 

1974 the stratosphere had become extremely c lean with scattering ratios 

41 
I ~ 

(f) 

"f 

Q 5 -~ 

~ 

0 

u 

(f) 

~ 

u 

0 

en 

~ 

Cl> 

>. 

0 

_J 

0 

c 

.Q 

a. 

:> 

.... 

w 

0 

c 

0 

0 

~ 

g, 

C1l 

:> 

l.J... 

JAN 1975 JAN 

Figure 24. Total backscatter of 

the Fuego dust cloud above Mauna 

Loa Observatory . 

approaching 1.05 or so in September. This points out that during the period 

from early 1973, when lidar measurements were first initiated , to October 

19 74 the stratosphere was still in the process of cl eaning itself from previous dust injections. 

The second major peak shown in Fig. 36 of Swnmary Report 1974 has been 

i dentified as faulty data . This discovery has simp lified the interpretation 

of the entire event. 

During 1975 an attempt was made to extend the aerosol studies down into 

t he troposphere. Fig. 25 displays the average aerosol backscatter coefficient for three altitude regions. In t he 13-15 km region , which is just 

beneath the standard tropi cal tropopause , the aer osol backscatter coeffi -

c i ents were much higher during the spri ng and early summer than at other 

times. The l e ngth of the data record prevents a determination of whether 

this is a seasonal effect or associated with the transfer of Fuego aerosols 

from the stratosphere into the upper troposphere . Analysis of the 1976 data 

s hould c l arify this point. 

The region between 19-21 km shows the gradual decreasing trend from 

early 1973 to late 1974 followed by sudden increase due to the Fuego inject i on and a subsequent decli ne . 

The 21-23 km region s hows a sli ght decreasing trend prior to the erupt i on , subsequent increase , and return to l ower l evels. On the basi s of thi s 

information , there appears to be no obvious upward transport of stratospheri c 

aerosol s . 

42 
..... I 

..... 

(/') 

..... I 

~ 

(J') 

I 

0 

70 

60 

50 

40 

30 

20 

10 

• • · · · · · · · 13- 15 km Region 

--- 19-21 km Region 

------ 21- 23 km Region 

1973 1974 

t 

,, 

, , 

t\ I I 

I

I \ I I 

\ l'J I I ·' . J I •• \.J . I 

I .. '1 . I 

I • • • • I 

I • I 

I • I 

.. I •• .'t . · 1. .f:\J • . • ... ... I • 

I : 

1975 

Figure 25. Mon thly averages of the non-Rayleigh backscatter coefficient at 

di fferent elevations above the Ma una Loa Observatory . 

In general , the result from one evening of lidar observati ons i s a profile of aerosol backscatter coeffi c i ent fr om 13 to 25 km MSL with a normal 

he ight resolution of 300 m. Fig. 26 s hows typical profiles t a ke n during 

1975 . By April 9 the stratospheric dust c l oud, l ocated at approximatel y 20 

43 
Figure 26. Typical Rayleigh 

backscatter coefficient 

profiles above Mauna Loa 

Observatory . 

A--April 9 

B--June 25 

C--December 10 

10 0 50 

km had diffused considerably in vertical extent and had reached its maximum 

average reflectivity . It is interesting to note that the upper tropospheri c 

aerosol concentration was higher than it has been observed at any other t ime , 

for which we have no explanation. By June 25 the dust cloud had become much 

reduced in total reflectivity. The tropopause , l ocated near 16 km, shows a 

local minimum in aerosol concentration and the aerosol concentration below 

the tropopause remains at extremely low values. On December 10 the dust 

c l oud was more ragged and further reduced in aerosol concentration. The 

relati ve minimum in aerosol concentration is l ocated slightl y below the 

tropopause. 

Emphasis will be placed on extending the profiles to lower altitude~ 

during 1976. 

4.2.2 Clouds 

Since early 1973 when lidar studies were first initiated at Mauna Loa 

Observatory, it has been apparent that useful cloud information in the upper 

troposphere would be a natural by- product of the lidar studies. It is known 

that the presence of cirrus cloud layers in the high troposphere can have 

substantial effects on the Earth ' s radiation budget. However , reli able information on the spatial, temporal , and optical properties of these c l oud 

l ayers has been lacking in the past. By use of lidar, it is possibl e to 

measure the height and thickness of cirrus layers and , in principle , it 

should often be possible to calculate the opti cal thickness at the laser 

wavelength. 

44 
100 

Figure 27. Non-Rayleigh backscatter coefficient profile for 

Mauna Loa, May 12, 1975. Note 

cirrus layer at 13.5 km. 

Fig. 27 shows a 15-minute average of a cirrus cloud in a typical lidar 

analysis. The cloud was located at about 13.5 km and had a thickness of 

approximately l km. It is hoped that a complete analysis of all lidar cloud 

data from early 1973 will be completed in 1976 . 

4.2.3 Barrow System 

In early 1975 a decision was made to expand the lidar program by installing a system at Barrow, Al aska , to provide needed information on atmospheric 

scattering properties for Northern Hemispher e regions. Although somewhat 

smaller, this lidar system will be similar to the Mauna Loa system. It will 

be located in a 2.5-m-square wanigan near the GMCC Observatory. Work during 

the year focused on procuring the necessary components and setting up the system in a portable trailer at Mauna Loa so that its enti r e operation can be 

checked before it is installed at Barrow. 

SYSTEM DESCRIPTION 

The transmitter portion of the laser system will be a 3-joule dye laser 

with a wavelength of 5900A, transmitting at the rate of 3 pulses per minute. 

The receiver portion of the lidar consists of a 41-cm-diameter plastic Fresnel lens, a colored glass type filter, and a phototube. The opti cal system 

will be a collinear arrangement so that the laser and receiver beams will be 

overl apped to ground level , eliminating the near field effect. 

The signals coming in from the phototube are digitized by a Biomation 

transient digitizer. They are then fed into a CAMAC system. This system 

utilizes a NOVA minicomputer for crate control and data processing functions. 

45 
Lidar operating programs and intermediate tempor ary data are stored on a 

cassette tape drive . Periodically, upon command from the ICDAS system, lidar 

results are sent along a send/receive line to the ICDAS in the main building 

for archiving. The CAMAC system will monitor the various functions of the 

transmitting and recei v ing systems and will control the entire lidar operation as well as shut the system down in the event of a system f ailure . 

Atmospheric profiles will be displayed on an oscilloscope for immediate 

operator interpretati on as necessary. 

The lidar system will initially operate continuously to provide profiles 

o f aerosol concentration as well as low and high l evel c l oud data . It may be 

slowed l ater to give lower time resolution and therefore extend the laser 

component lifetime. 

4.3 Surface Aerosol Measurement s 

4.3.l Mauna Loa 

Short- tube Gardner counter SN826 was operated in January and long-tube 

Gardner counter SN1176 was operated through the remainder of 1975 . Pollak 

counter SN13 was operated throughout 1975. Observations were taken hourly 

during the normal worki ng day. Fi gure 28 shows monthly geometric means of 

Pollak counter observati ons. The daily upslope wind effect i s c l early evi -

de nt as shown by the high afternoon concentrations. However, there is no 

obvi ous annual trend in the 1000 LST readings, although it was expected that 

a trend with a peak in the summer would be observed because of t he annual 

trend in lightscattering data obtained by the nephelometer . Overall , morning 

concentrations are fairly low, 200-250 CN cm-3 , representative of background 

conditions; the site cleanl iness deteriorates with the afternoon upslope wind 

from below. Figure 29 shows the annual geometric means of the Pollak counter 

data . 

Gardner counter SN1176 (long- t ube) was calibrated by means of a twomonth comparison with Pollak SN16 at Mauna Loa . Fi gure 30 shows the results 

of t his comparison along a l east-squares fit of Hoerl's equation: 

l og y a + b log x + ex. 

A calibration table for Gardner SN1176 was then generated to convert the 

Gardner scale divisions to nucl e us concentrati ons. 

A General Electric Conden sati on Nucleus Count er was installed at Mauna 

Loa i n the summer of 1975 . Although there were several short peri ods of 

reliable operation, in general the G. E. counter suffered from maintenance 

probl ems and few u seful data were obtained. 

46 
,,, 

'E 

u 

z 

u 

1000 

n n 

M A 

n n n n n n 

M A 0 0 

Figure 28. Monthly geometric means of condensation nuclei for 1975 at Mauna 

Loa Observatory , for 1000, 1100, 1200, 1300, and 1400 LST. The shaded dots 

indi cate the 1000 LST values; n indicates the 1200 LST value; the vertical 

bars give standard errors about the mean (S . E. = a//;;) . 

NEPHEWMETER 

The Mauna Loa four-wavelength nephelometer operated reliably throughout 

1975. Onl y six weeks of data were l ost during the entire year. Furthermore, 

the instrument exhibited onl y nominal drift and the rather strict calibration 

schedule of a monthly Freon calibration and a weekly relative calibration 

proved more than adequate . 

IOOO 

~ 

r0 

z 

(f) 

.Y 

..2 

0 

Q_ 

10 

I 

E 

u 

z 

u 

100 1000 1100 1200 1300 

Time of Doy 

1400 

Figure 29 . Annual geometric means of 

the hourly observations of condensation nuclei for 1975 at Mauna Loa 

Observatory. Vertical bars give 

standard errors about the mean 

(S . E. = a//;; J. 

47 
10,000 .---.--~----r-------.--,--------.--, 

Figure 30. Comparison of long-tube 

Gardner counter SN1176 data with 

Pollak counter SN16 data on ambi-

<.O 1,000 

z 

Cf) 

.:.:. 

u 

.Q 

& 

ent aerosol at Mauna Loa Observa- 1: 

tory during June and July 1975 . u 

z The curve shows a least squares u 100 

fit of Hoe rl ' s equation . log y = 1.699 + 0.8264 log x 

+0.02596x 

IO 35 30 25 20 15 10 5 

Long Tube Gordner SN 1176 Scale Divisions 

Figure 31 shows means of hourly averages for sel ected months of 1975 . 

0 

Al l months show the usual diurnal eff ect and , in general , background light 

scattering is about an order of magnitude higher in the spring than in winter. However , note that the afternoon peak remai ns approximately the same 

throughout the year . The Angstrom exponent (a ) s hows rather large variations 

among the four sel ected months. In general, the small values of a in May 

indicate a tendency toward l arger sized particl es, whereas the l arge values 

of a in winter months s uggest smaller si zed particles. The odd behavior of 

the 850-nrn curve i n October i s probably due to instrumental problems . The 

nephelometer i s sensi t ive primaril y to particles with radii of 0 . 1 t o 1.0 μm. 

Figure 32 shows the annual trend for light scattering at Mauna Loa . 

Each point i s the geometric mean of the 0300 to 0400 LST hourly average for 

all days of e ach month. The seasonal trend i s apparent with high lightscattering in the spring and very low or clean va lues in the winter . Furthermore , a s hows erratic behavi or during the spring and summer with a tendency toward larger sized particles, and fairly stable behavior duri ng winte r 

with higher values of a ) and a tendency towards sma ller sized particles . 

The reason for this annual trend in background air is not entirely understood. However , i t i s probably due t o a general increase of s uspended part i culate in the summer troposphere and to the motion of the atmospheric 

general circulation with season. 

48 
MARCH MAY 

~----~----------~ 

5 

~ g-c g tj ~ -

C'~ • 

.lf ~ o:·, .. ./ 

DECEMBER 

-8 10 o~o ------------~24 oo 24 

Figure 31. Monthly geometric means of hourly averages from the Mauna Loa 

four-wavelength nephelometer for 1975 . The Angstrom exponent 0 12 is derived from 450 and 500 nm, a23 from 500 and 700 nm, and a34 from 700 and 

850 nm . 

To obtain a better understanding of these data it is useful to examine 

the continuous record and correl ate it with local me teorological parameters. 

As an example, hourl y ave ~ges of bsp (550 nm) for October are given in Figure 33 , along with hour l y aver ages of relative humi dity and wind speed and 

direction pl otted at 3-hour i ntervals. A background level of approximately 

l o-7m-1 i s apparent with various perturbations superimposed. There is obvious correlation among the three parameters. Winds with an upslope (northerly) component are usually associated with hi gh lightscattering values and 

downslope (southerly) winds produce the l owest lightscat tering values. The 

c l assical upslope-downslope effect is clearly evident much of the time (e.g. 

Oct. 27-31) with high afternoon values of lightscattering , an increase in 

relative humidity , and a return to background conditions during nightti me 

hours . Also , during winter months , it i s not unusual to encounter an extended period of st rong southeasterly winds accompani ed by l ow rel a tive 

4 9 
10 

10 •~-..---..---.,---.-----r--,---.----.---.--. --. -, 

1975 

o 450nm 

• 550 nm 

a 700nm 

"' 850 nm 

Figure 32. Monthly geometric means of lightscattering and Angstrom exponent !_or all 0300-0400 LST averages at Mauna Loa Observatory in 

1975. a is the average of a12 (450-550 nm) and a23 (550-700 run) . 

humidity and extremely clean conditions (e.g. Oct. 1-5, 15-18, 23-28). These 

periods o f h i gh winds usually produce the l owest lightscattering values and 

often complet ely overpower the local diurnal wind c i rculation. 

4.3.2. Barrow 

Lo ng-tube Gardner counter SN1143 was operated r outine ly throughout 1975 . 

During January-April , a comparison was conduc t ed on ambient aerosol between 

short-tube Gardner SN1098 , which had been u sed during previou s years at 

Barrow, and the new long-tube SN1143. About 400 comparison points were 

obtained a nd a least squares f it of Hoerl' s equation was produced to give 

Figure 34. Although use of the short-tube Gardner was discontinued in favor 

of the more sensitive l ong-tube unit, with the comparison s hown in Figure 34 

previous data can be corrected to provide continuity across the transition. 

In October 1 975 , Pollak counter SN16 was put into operation at Barrow. 

Previous to shipment, this Pollak was compared with Mauna Loa Poll ak SN13 to 

produce the data shown in Figure 35. The least squares s traig ht line s h ows 

excellent agreement between the two counters, especially between scal e readings of 90 and 100 which correspond to nuc l eus counts of between 3 15 CN cm- 3 

and 0 . In this region, agreement between the two Pollak counters is cons ide rably better than 1%. 

From October 1975 to March 1976, a comparison between long-tube Gardn er 

SN1143 and Pollak SN16 was conduct ed on ambient Barrow aerosol and the 

results, along with a least squares fit of Hoerl's equation , a r e shown in 

Fi gure 36. The curve serves as the current calibrati o n for routine Gardner 

counts at Barrow and previous observations taken with short-tube Gardner 

50 
'\'\'\~~'\'\'\'\'\'\'\°l'\'\'\'\°lcr"'°"'\'\'\') '\'\'\'\'\~ '\'\,'\ o..<T"'\'YVJ ~'-o'o l'f r yl.t ~ y7l.tb<o~y j'o~crq_a...<l,a...o&t 6 ~i 

100 

::~ 8 I 2 3 4 5 6 7 8 9 ~o 10 

Y.J' oh/, ~.J' 0 /, /, o<lo ~b ""o"'\'\'\'\ '\~ [,c{b Q,°)'\°'00<>.!'\ '•{'i'Y' f?o(~.,'\'\ '\°""°'I~ j O,.,"i~°'°J J ?'ob\, ocy7 p ~"cl'\")°) 

..... ,...,.,..-,....J'-'"'-.....1100 

E 0 c 

~::~ .2 -

5 11 12 13 14 15 16 17 18 19 20 

0 ~ 

I 

a: 

Figure 33. Hourly averages of 550-nm lightsqattering and relative humidity 

at Mauna Loa Observatory for October 1975. Wind direction and speed at 

3-hour i ntervals are shown . 

SN1098 may be correc ted by using Figures 35 and 36 or by a numerical solution 

of the two Hoerl's equations. 

Figure 37 gives a wind rose and condensation nucleus geometri c means as 

a function of direction f or October-December. These data were taken with the 

Pollak counter. The mean concentration of 131 CN cm- 3 for clean air directions is considerably l ess than concentrations measured in previous years 

because of the increased sensitivity of the Pollak counter and because a 

geometric mean is a lways less than an arithmetic mean . These differences 

will be reconciled i n the future since all observatories are supplied with 

similar equipment and past data can be corrected i n terms of current measurement techniques and updated c alibrations. 

51 
Cl'.) 

(J) 

Q 

z 

(f) 

Qj 

c 

12 

0 

(.? 

~ 

~ I 

I... 

0 

.£: 

(f) 

z 

u 

log y = 2 059 + 0.2455 log x + 

004304 )( 

30 25 20 15 10 5 0 

Long-Tube Gordner SN 1143 Scale Divisions 

Figure 34. Comparison between shorttube Gardner SN1098 and long-tube 

Gardner SN1143 on Barrow ambient 

aerosol during January -April 1975 . 

Curve shows least squares fit of 

of Ho erl ' s equation . 

100 

g. 

'8 90 

& 

..9:! 

0 

u 

(f) 80 ~ 

..::.:. 

0 

& 

70 

6060 

y = 3.887 + 09572 )( 

r =0.98291 

n= 195 

ro so 90 

Pollak 13 Scale Readings 

100 

Figure 35. Comparison between Pollak 

SN16 and Pollak SN13 on Mauna Loa 

ambient aerosol during March and 

April 1975 . 

Ta ble 12 gives monthly geometric means for 1975. Also given are the 

number of data points (n) and the logarithmi c standard deviation for each 

mean (log o) . Overall, t he Barrow observatory is a very clean site when the 

wind i s from N, NE , E, or SE. However, the effects of fog and snow should be 

investigated more thoroughly to eliminate the effects of local scavenging 

which may produce unrealisticall y low nucleus concentrations. 

4.3.3 Samoa 

Because of the facility constructi on and its demand upon the GMCC 

observer ' s t ime , very few surface aerosol data. were obtained from Cape 

Matatula during 1975. As no meaningful conclusions can be drawn from these 

data, they will not be presented. 

52 
lD 1000 

z 

Cf) 

~ 

.2 

0 

Q_ 

,.., 

I 

E 

u 

• t '. 

Figure 36. Comparison between 

long-tube. Gardner SN1143 and 

Pollak SN16 on Barrow ambient 

aerosol during October-December 

1975 and January-March 1976. 

z 

u 

100 log y = 1.745 + 0 8898 log x + 

0.02078 x 

n = 467 Doto Points 

30 25 20 15 10 5 0 

Long-Tube Gardner SN 1143 Scale Divisions 

Number of Observations 

to Gi ve Mean for 

Given Wind Direction 

\ 

Aitken 

Nucleus 

Concentration 

32 

N 

t 

17 

Percent of Observations -4--~ 

with Winds from 33 

Given Direction 

56% of Winds from 

Clean Air Direction 

Average Aitken= 131 

53 

Figure 37 . Barrow wind 

rose and condensation 

nucleus geometric 

means f or OctoberDecember J. 97 5 . 
Table 12. Monthly Geometric Means of Aerosol Measurements at Barrow 

19 75 JAN FEB Mf,R APR MAY JUN JUL ~ SEP OCT NOV DEC 

x 8 7 210 285 252 1 2 3 47 325 232 174 4 5 160 224 

log o 0.45 0 .19 0 .16 0 .16 0 . 30 0 .48 0. 51 0 . 6 2 0 .51 0 .41 0.21 0.28 

n 79 64 86 92 144 88 72 77 73 41 39 68 

In CN cm-3, for clean a ir direction (N-SE ). 

4 . 3.4 South Pole 

Pollak counter SN15 continued t o operate at South Pole station throughout 1975. Observations were obtained daily at 0100 GMT and 0800 GMT, during 

uncontaminated wind conditions, from the "clean air" facility at the new 

South Pole station. Sample air was brought into the instrument through the 

aerosol and gas sampling manifold designed for use at all GMCC sites. The 

manifold incorporates a high volume blower that draws air through a 6-in 

diameter stack and is distributed by means of isokinetic sampling probes to 

the various instruments. 

Daily a erosol counts for August, September, and October 1975 are shown 

in Figure 38. Also shown are air temperature, wind speed, and wind direction 

at the time of the observation. Figure 39 gives the monthly geometric means 

of daily Pollak nucleus observations. 

It is evident that very low condensation nucleus concentrations were 

encountered during the winter months with a low of about 10 CN cm-3 during 

July. As the austral summer approached, nucleus counts increased with a 

large jump in late September, about the time of sunrise. The very low concentrations during winter months are probably produced by removal forces 

acting beneath a strong temperature inversion that prevents mixing from 

aloft. Breaks in the inversion, accompanied by subsidence and photochemical 

processes, cause the increased values during summer months (Hogan, 1975; 

Hogan and Nelson, 1975). 

The General Electric Condensation Nucleus Counter was modified and installed at Pole according to the design developed by the University of 

Washington and adopted for all GMCC observatories. In this configuration, 

the G.E. counter showed good stability and was sensitive to below 10 CN cm-3 

Continuous chart recorder data were obtained for all of 1975. 

During 1975, long-tube Gardner counter SN1183 wa~ present at Pole as 

backup for the Pollak or as a portable instrument for outdoor work. However, 

this instrument does not have sufficient sensitivity for nucleus observations 

at Pole. Thus the Pollak counter will continue as the standard observing 

instrument. Figure 40 gives the calibration curve obtained for Gardner 

SN1183 in a comparison with Pollak SN16 at Mauna Loa Observatory. 

54 
r...> ., • .J ('.I..., 11., •• J ... !! '\).J ...,.,, .... ~ rr.r°"'""'..,.,.-....r ........ LL.!..., ... ~LJ.rr~ 

z 

u 

100 

80 

I 

E 60 u 

z 40 u 

20 

September 1975 

' I 

·o 

0 

. 'Q 

0 0 

• 0 • 

'-4--L-'--'--'--'---"--"'---1-c-'---'---'-~~-'---'--"--'-~~~ ~-'":c:--:-:~-:-::' 

2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 

!<) 

'E 

u 

z 

u 

160 

0 

'?. 0 

·oo 0 

0 9 0 

6 

• 

0 

'? 

0 

0 

• 0 

0 0 

0 

0 

0 

0 

Q 

-60 E 

~ 

-80 

20 

'-'-2~~4~~6~~8~ 10~ 12 ~1~~18.,..---:-:-20 

-40 

- 60 LL 

~ 

-80 Q 

-100 

-40 

LL -60 ~ 

Q 

-80 ~ I-

-100 

E 

~ 

Figure 38. Condensation nucleus concentrations at South Pole for selected 

months of 1975. •, Pollak counter; o, G.E. counter. 

55 
Figure 39. Monthly geometric means 

of condensation nucleus concentrations at South Pole for 1975. Vertical bars give standard error of 

the mean (S. E. = a//;) . 

Fi gure 40 . Calibration curve for 

long-tube Gardner counter SN1183 

produced by comparison with Pollak SN16 at Mauna Loa Observatory. 

r<l 

'E 

u 

z 

u 

56 

r<l 

I 

E 

u 

z 

u 

J FMAMJ JASO NO 

Year 1975 

I035 30 25 20 15 10 5 0 

Long-Tube Gordner SN 1183 Scale Divisions 
4.4 Meteorological Measurements 

4.4 .1 . Meteorological Sensors 

In the past a wide variety of sensors have been used to measure wi nd , 

temperature , and pressure at GMCC o bse rvatories. Historically such measurements were initiated in support of a specific gas or aerosol monitoring program. In 1975 the measurements of wind, pressure , temperature , and humidity 

were standardized and sets of sensors were depl oyed at all station s . These 

sensors were supported by a set of translators that prepare the ou tpu t for 

digitizing and recording. 

With respect to wind, all stations except American Samoa had a propeller 

type anemometer installed at the time sampling started. Wind records are 

used to define periods when loc al air flow is from an established c l ean air 

sector. At all stations the anemometer is positioned at about the same 

height that gas samples are taken , usually between 10 and 16 meters above the 

s urface. Wind speed and direction are recorded on a strip chart recorder to 

provide the observers a continuous visual display. 

Fluctuations in station pressure as measured by local NWS stations would 

suffice to correct gas and aerosol measurements to standard pressure for all 

stati ons except the Mauna Loa Observatory . However, to d e termine the optical 

depth of the atmosphere a more accurate measurement of station pressure i s 

r equired. Continuous measurements of station pressure a re made with a static 

pressure transducer, (Fig. 41) to obtain a voltage that can be digitized , and 

with a microbarograph , for visual display. Both are calibrated twice a week 

with a mercuri al barometer . 

In addition to the gen e ral requirement f or air temperature readings to 

correct gas and aerosol data to standard condition s , some sensors are tempe rature sensitive and specific response corrections must be applied. A linearized , thermistor composite was chosen a s the sensor because its sensitivity 

makes it independent of line resistance . Liquid-in-gl ass the rmometers are 

s upplied to each station. 

Relative humidity is measured except at South Pole where the humidity is 

b e low the detector ' s sensitivity. In addition to being an important factor 

in the operation of condensation nucleus counters, rela tive humidity is also 

an excell ent indicator of upslope and down s lope wi nd condition s at the Mau na 

Loa Ob servatory. The temperature and humidity sensors are exposed in an 

aspirated radiation shield which is mounte d at or near standard shelter 

height , 2 to 3 meters (see Fig. 42) . At the low-latitude observatories a 

hygrothermograph provides a backup to the electrical sensors in addition to a 

displ ay of t empe rature and humidity to the observers. 

Based on the program requirements (sensitivity, range , etc.), the foll owing sensors were purchased and combined into a single me teorol ogi cal 

system for use at each of the four field s tations: 

5 7 
Figure 41. Translator crate to the 

meteorological sensors. It contains the printed circuit cards 

and power supplies to calibrate 

and scale the voltages from the 

sensors. The pressure transducer 

is mounted in the lower right. 

Wind speed and directi on: 

Pressure: 

Temperature : 

Relative humidity: 

Figure 42 . Aspirated radiation shields 

for both the air temperature and relative humidity sensors. The shields 

guarantee exposure error to be less 

than 0 .1 °C . 

Aerovane Model 120, Bendix Corp . 

Static pressure transducer , 

Model 1201C Rosemount Inc . 

Linearized thermistor, Model 44212, 

Yell ow Springs Instrument Co. 

Model lHM-lllP humidicap , Helsinki. 

Support electronics for these sensors are in the form of printed circuit 

cards. These , together with reference voltages, amplifiers, a nd power supplies are mounted in a translator case (Fig . 41). The vol tages from a ll 

sensors are sampl ed once per second , and 1-minute and 1-hour averages a r e 

computed and recorded on magneti c tape i n digital form by the Instrument 

Control and Data Acqui sition System. 

4.4. 2 Mauna Loa Meteorology 

Figure 43 shows the seasonal d i stribution of the wind direction and 

speed to a resolution of one month. In the two-dimensional p lot t he predominant wind direction, southeast, is seen as a constant feature throughout 

19 75. Another maximum is observed for the north and northeast directions 

during the s ummer months. The frequency of occurrence of calm conditi ons for 

each month i s also presented. The average monthly percentage of calms in 

1975 i s 0. 6 percent. Except in April and May the average wi nd speed of the 

southeasterlies i s greater than 5 ms- 1 • The average speed for the year 1975 

i s 4.3 ms- 1 • The frequency of the wi nd direction and the average wind speed 

for each direction are a l so plotted. The maximum wind speed clearly corresponds with the predominant wind direction--southeasterly. 

58 
Frequency I 1 l \1ar Apr lay Jun Jul Aug Sep Oct Nov Dec 

Frequency I 1 l of 

\Vind 01rect1on (0o, Bar Graph 

D 0 10 20 30 40 

o.o 0.9'• 

Frequencyl21 of 

Calms for Each 

Month ( 11 

Average \'hnd 

S11eed for 

Each Moru h of 

Year (ms 11 

N 

NE 

E 

SN 

\'/ 

Sms 1 

2 ms 1 

10 15 

A1Jt>tage \'/ind Speed for 

EJr.h D1rect1on (ms 1) 

Line Above 

Figure 43 . Surface wind data for Mauna Loa Observatory, 1975 . 

(See legend, fig . 50) 

HILO RAWINSONDE DATA 

20 

The pilot program started last year to evaluate upper air soundings 

taken at the Hil o Airport, 55 km northeast of the Mauna Loa Observator y , was 

extended through 1 975. The upper air data w~re used to interpret the GMCC 

baseline data measured at Mauna Loa Observatory . Three sets of data were 

computer processed from the rawinsonde soundings: (1 ) twice-dail y computations of total precipitable water above the elevation of Mauna Loa ; (2) computations of the gradient (850 mb) and jet stream (250 mb) wind layers; (3) 

t abulati ons of daily tradewind temperature inversions and moisture cutoffs in 

relation to the height of the observatory. 

Figure 44 is the plot of precipitabl e water in 1975 above the e l evation 

of Mauna Loa Observatory. Maximum excursi ons of precipi table water occurred 

during the winter half of the year. These peaks of up to 12 mm are the results of synoptic storm passages over the islands when precipitation usually 

occur s . During the summer half of the year the trade wind inversion caps the 

moist maritime layer and dry conditions prevail abo~e the observatory . The 

tradewind inversion , though not as persistent, i s also pre sent during the 

winter half and produces most of the dry conditions during this time of the 

59 
10 

E 6 E 

4 

2 

0 

. . 

. . 

. . . , 

... . . . . 

.: .. 

JAN 

. . . 

, 

. . 

.. 

. .. . . . . \ . . . . ... .. . . . . . .. . . . . . . .. . .. .,.. ·:·· .. . . 

FEB MAR 

. . . . . . . .. .. . . .. • • • • • •• • •• .# : 1: • :. •• .. •• , ........... ,.,,,,. ~ • 4l... • 

·· · : ., • · ·'i. r . ' · ··y.. i' • 

,:' • I ', , • •: , .. A .. • ' ,• , I .. 

APR MAY JUN JUL AUG SEP OCT 

. . . ... · . . ..... . ... . , 

NOV 

. . 

. .. . 

.. .. . 

.. . · . 

DEC 

Figure 44. Total precipitable water above Mauna Loa Observatory in 1975. 

Values were computed from NWS Hilo rawinsonde observations, twice daily, 

55 km from the observatory. Daily as we ll as seasonal variations are 

evident . Large excursions correspond to synoptic storms and are prevalent during the winter half of the year. 

year. Note also that the drie st days occur during the winter half of the 

year when only ~ 0. 6 mm is observed above the observatory. These are a l so 

the better optical v i ewing days during the year. 

The plot of cutoff tradewind temperature inversions as determined from 

the Hilo soundings is shown in Figure 45. A cutoff tradewind temperature 

inversion is de fined as one in which the mixing ratio drops from about 6 to 

10 g kg-l to ~ 2. 0 g/kg across the inversion layer. Such inversions usually 

separate a moist sub-inversion layer from a drier upper tropospheric air mass 

and inhibit extensive vertical mixing. These inversions generally form below 

the elevation of the observatory and act as a barri er to the upward transport 

of more turbid marine air past the observatory. The persistency of occurrence intensifies during the summer half of the year and consequently the 

inversion is more effective in cutting off moisture from higher level s in the 

summer. 

60 
10.-----------,--------.-----:-------r-----, 

8 

E 

~ 6 - -

E 4 i 'I .2' 

Cl) 

I 

2 

0 

"E 80 ~ 

....... 

~ 

'•' 

~ 60 - .i:::. 

g. 40 

~ 

(/) 20 

I 

10 ---~-~~~-----~-.,----~-r-~~~,--, 

8 -

~ 6 - -

E 

.Q' 41 .... Cl) 

I 

0 

~ 80 ....... 

u 

~ 60 

:E 

g' 40 Cl) 

...... 

(/) - 20 

0 

·1, '1 

' I 

A~1 i 

JUL 

Figure 45. Cutoff tradewind temperature inversions as determined from the 

NWS Hilo rawinsonde data, twice daily for 1975. The mixing ratio decr eases 

across the inversion from 6 to 10 g/kg to ~ 2 . 0 g/kg . Note that the position of the inversion is just below the elevation of the Mauna Loa Observatory where it acts as a barrier to v ertical mixing especially during the 

summer half of the year when the inversion is more persistent and stronger. 

61 
Figures 46 and 47 are sample plots of the gradi ent and jet stream wind 

layers. In both cases the full year' s record shows a significant daily 

variability in the height and thickness of the layers. The direction of the 

gradient wind layer is predominantly from the east with a shift to the southeast during the winter. The upper extent of the layer is usually just below 

the elevation of the observatory. The wind flow is gentle and very consistent throughout the year. 

The j et stream is significantl y greater in vertical extent having an 

average vertical thickness of ~ 5.0 km with a maximum in later winter into 

spring . This maximum in thickness coincides with the annual maximum in 

speed. The jet stream is from the west with short periods from the north or 

northeast. These short periods are the result of upper-level synoptic lowpressure systems and represent periods of downward vertical transport rather 

than zonal transport from the east. 

Summary. Computer processing of NWS Hilo rawinsonde data for 1975 

showed the precipitable water content above the observatory to average about 

2.6 mm , but to have great daily as well as seasonal varability. The cutoff 

tradewind inversion acts as a barrier to vertical mixing and vertical moisture advection above the observatory especially during the summer half of the 

year. It also showed the vertical extent of the trades to be close to the 

height of the observatory, with a cutoff temperature inversion embedded in 

the trades at about 0.8 km below. 

A deep westerly flow that persists above the observatory intensifies 

during winter and spring and can extend as low as to the height of the mountain top. This steady upper-level flow provides a constant replenishment and 

circulation of upper tropospheric air over the observatory for geophysical 

benchmark monitoring. 

4.4.3 Barrow Meteorology 

Perched on the poleward extension of the Alaskan north slope , the GMCC 

observatory at Point Barrow is exposed freely to the wind from all directions. There are no significant topographic barriers within a 300 km radius 

of the station. The surface wind is, therefore, determined mostly by largescale synoptic weather features and not by l ocal topography. Between stormy 

periods when the wind is variable , the local winds are controlled by the 

outflow from the polar anticyclone which produces a persistent easterly wind 

at the surface. The most significant local phenomenon is the onset of the 

stratus cloud deck in the spring. It corresponds with the t ime the sun is up 

for most of the day, and the time when extensive leads in the Arctic ocean 

open along the coast. 

In figure 48 the seasonal variation of the wind speed and direction are 

displayed. Easterly winds are clearly the most preval ent in all months of 

the year. When directions north through southeast are included , the frequency of occurrence for 1975 was 59%. The secondary maximum i n the wind 

direction distribution is from the west. This could be interpreted as a 

diurnal occurrence were it not that the prevailing wind direction is easterly 

for all hours of the day. Westerly winds were most commonly observed in the 

62 
E 8 

c 

1: 

~ 6 

I 

.... 

~ 4 0 

_J 

-0 

c 3 2 

~ 

E 

0 

-g 40 Q) 

a. 

(/) 

.... 

~ 20 0 

_J 

-0 

c 3 0 

36QO 

c 90° 

.Q 

u 

Q) c5 180° 

.... 

Q) 

>. .3 270° 

-0 

c 

3 360° I 

5 10 15 20 25 31 5 10 15 20 25 28 5 10 15 20 25 31 5 10 15 20 25 30 

Jon Feb Mor Apr 

Figure 46. The gradient wind layer (850 mb) as plotted from NWS Hilo 1975 

rawinsonde data. The v ertical bars show the height and thickness of the 

layer. Wind speed and direction are the vector sums of the 1'1hole layer. 

Note that the upper extent of the layer is just below the elevation of the 

Mauna Loa Observatory and represents the tradewind flow over the islands . 

summer and winter months. The seasonal variations in wind speed are not 

pronounced though the speeds seem to be a little higher in winter months. 

The seasonal variation as a function of wind d irection is more pronounced 

showing a maximum corresponding to the most prevalent wind directions. Calm 

conditions were reported an average of 1.1% of the t ime in each month . The 

average wind speed for the year at Barrow was 6.5 ms- 1 • The maximum speed 

was observed on February 7 at 14.3 ms- 1 • 

63 
IO I I I I I I I I I I I I I I I I I I I I I I I 1 

~ 

E 

"O 

Q) 

Q) 

a. 

(/) 

.... 

Q) 

>- 0 

....J 

"O 

c 

3 

c 

0 .-5 

Q) 

8 ._____ 

6 -

o40 

20 

0 

c5 180° 

"O 

c 

3 360° I 

MLO -

5 10 15 20 25 31 5 10 15 20 25 30 5 10 15 20 25 31 5 10 15 20 25 31 

Moy Jun Jul Aug 

Figure 46. Continued. 

In 1975 the National Weather Service station in Barrow reported a 

minimum temperature of -47°C on January 3. The maximum reading was 18°C on 

July 7. The average temperature for the year was -14.6°C, a departure of 

2.0°C from normal. These values are computed from the NOAA, Environmental 

Data Service, Local Climatological Data report for the airport station at 

Barrow, Alaska. These temperature statistics are probably more representative of the village of Barrow and thus generally warmer than at the GMCC 

observatory, located approximately 7 km to the northeast. 

Generally, after the Arctic ice pack breaks away, and large leads open 

in the ice, the stratus deck moves over Point Barrow to remain as a persistent feature of summer and fall. The stratus is usually established by the 

64 
14 I I I I I I I I I I I I I I I I I I I I I I I I I 

12 1--

E 10 -- .Yo 

~ 

.... 

Q) 

_J 

~ ~ 

"O 

c 

~ 

~ 

E 

-0 

Q) 

Q) 

a. 

(/) 

4 I0 .___ 

40 

Qj 20 >. 

0 

_J 

"O 

~ 0 

360° 

c 

,g 270° u 

Q) 

.... 

~ 180° Q) 

>. 

0 

_J 

"O 90° c 

~ 

360° I 

-

-

-

MLO 

5 10 15 20 25 30 5 10 15 20 25 31 5 10 15 20 25 30 5 10 15 20 25 31 

Sep Oct Nov Dec 

Figure 46. Continued. 

middle of May. The average monthly cloud cover , midnight-to-midnight reported for the Barrow airport station , for January through April and November 

through December 1975, i s 4.5/10. For May through November the average 

monthly cloud cover was 8 .4/10. Typically, in this 6-month c l oud period only 

16 c l ear (0/10 to 2/10 cloud cover) days can be expected. With the stratus 

present the ceili ng ranges from 0.2 to 0. 5 km, in the absence of preci pitation. 

65 
22 

20 

18 

E 

.><: 

E 16 Ol 

·a; 

I 

..... 

Q) 14 >-

0 

_J 

" c 12 ~ 

10 

8 

~ 6 

E 

" E Q) 40 

i Q) 

0.. 

(f) M ..... 

Q) 

>-

0 20 _J 

" c 

~ 0 

360° 

c 

0 270° ·n 

Q) 

..... 

i:5 

..... 180° Q) 

>-

( , 0 

_J 

" 90° c 

~ 

360° 

5 10 15 20 25 31 5 10 15 20 25 28 5 10 15 20 25 31 5 10 15 20 25 30 

Jon Feb Mor Apr 

Figure 47. The jet s tream wind layer (250 mb) as plotted from NWS Hilo 1975 

rawinsonde data . The vertical bars shown the height and thickness of the 

layer. Wind speed and direction are the vector sums of the whole l ayer. 

The jet stream layer intensifies in winter and spring and its downward 

ext ent can reach to the height of the top of the mountain. 

66 
22 

20 

18 

E 

~ 

L; 

- 16 O> 

·a; 

I 

.... 14 Cl) 

>. 

0 

_J 

-0 

c 12 3 

10 11 I· 

8 

en 6 ....... 

E 

-0 

Cl) 

Cl) 40 a. 

(f) 

.... 

Cl) 

>. 

0 20 

_J 

-0 

c 

3 0 

360° 

c 

..g 270° (.) 

Cl) 

.... 

0 

.... 180° Cl) 

>. 

0 

_J /!\ -0 90° c 

3 

360° ' 

5 10 15 20 25 31 5 10 15 20 25 30 5 10 15 20 25 31 5 10 15 20 25 31 

May Jun Jul Aug 

Figure 47. Continued. 

67 
22 ' 

20 

18 

1: 16 Ol .(ii 

I 

~ 14 >. 

0 

_J 

-0 

~ 12 

10 

8 

~ 6 

E 

-0 

Q) 

~ 40 

Cf) 

~ 

Q) 

>. 

0 20 _J 

-g 

~ 0 ~ 

360° 

c 

~ 270° u 

Q) 

~ 

Ci 

~ 180° a.> 

>. 

0 

_J 

-0 90° c 

~ 

5 10 15 20 25 30 5 10 15 20 25 31 5 10 15 20 25 30 5 10 15 20 25 31 

Sep Oct Nov Dec 

Figure 47. Continued. 

68 
F requencyl 1l 

D 0.0 0.5% 

~ 

~ >0.5% 

>1.0% 

-> 2.0% 

Frequency121 of 

Calms for Each 

Month 1%1 

Average Wind 

Speed for 

Each Month of 

Year lms 1) 

Lme Plot 

Average Cloud Cover 

f or Each Mont.,_ 

Midnight to Midnight 

!Tenths) 

NWS, Barrow Airport 

Bar Graph 

Jan Feb Mar May Jun Jul Sep Oct Nov Oec 

SE 

s 

SSW 

5ms 1 

WS\V 

. . ('!' ,,..~ .. --=-----.. / . , I 

/ . , ' 

-f-·-yt7;1;7;;:~:;;:, '!--r-- ' . . ! ' : . t - " ·'·· ~ .. ; .. _....... . ...... : ... !y/ " ' / . ~ --+.... I : .,,,,,, 

--t-.-+ l < I 

10ms 1 

SW 

NWl---r--1• 

l I NNW L- --''--'--L-.l...1..-------..:'.b~-L .LI.-L-----_J 

0 

Frequencylll of 

Wind Direct ion IC\) 

Bar Graph 

10 15 20 

10 15 

Average Wind Speed for 

Each Direction (ms l ) 

Line Above 

20 

Figure 48. Surface wind and cloud data for GMCC Station, Barrow, Alaska , 

197 5 . (See legend, fig . 50 . ) 

4.4 . 4 Samoa Meteorology 

Figure 49 depi cts the monthly variation of wind direction and speed for 

Cape Matatul a for 1 975. The prevailing winds are east-southeast in every 

month of the year. They are especi ally persistent in the Southern Hemisphere 

winter months. In the austral summer months of December and January, the 

Intertropical Convergence Zone (ITCZ) moves further south bri nging stormy 

conditions and northerly wi nds. The pronounced absence of winds from th~ 

69 
Jan Feb Mar Jun Jul Aug Oct Nov Dec 

Frequency f 1) of 

Wind Direction ( 0o) 

Bar G raph 

Frequency I 1 I 0 10 20 30 40 

D 

0.0 0 .9°0 

>1% 

> 2% 

-> 3% 

Frequency 121 of 

Calms for Each 

Month ("'O) 

N 

NNE 

NE 

ENE 

ESE 

SE 

a 

t--~ -

0 5 10 15 

Average WrncJ Speed for 

Each Direction (ms 1) 

Line Above 

Figure 49. Surface wind data for Cape Matatula, American Samoa, 1975. 

(See legend, fig. 50.) 

20 

southwest is probably caused, in part, by the topography of the cape in the 

vicinity of the anemometer . Calm conditions were reported an average of 0 . 9 

percent of each month for the year. The average wind speed for the year was 

7.5 ms- 1 • The marginal distribution also shows a pronounced seasonal variation with the minimum speeds in December and January and maximums in May and 

July. The distribution of wind speed as a function of direction i s also 

well defined with the maximum of 10 ms-1 corresponding to the prevailing 

wind direction, SSE. The maximum hourly average wind speed measured at Cape 

Matatula in 1975 wa s 21 ms- 1 on May 19. 

4.4.5 South Pole Meteorology 

Throughout most of the year persistent radiation inversions control the 

local meteorologi cal conditions at the South Pole. Except for brief stormy 

periods in the spring this strong inversion serves to separate surface winds 

from conditions aloft. The stati on sits on the Amundsen-Scott plateau about 

2800 m above sea level. This relatively flat plateau, with little relief 

within a 100-km radius of the station, is in the larger scale depression near 

70 
the western edge of the main high ridge of East Antarctica. Surface winds 

are therefore controlled by the large-scale plateau. The direction of the 

persistent katabatic wind is easterly. 

All weather measurements for 1975 were made at the recently-completed 

Amundsen-Scott station. The instrumentation is located approximately 100 m 

grid-northeast of the station. (Direction grid-north is defined as lying 

along the Greenwich meridian). The anemometer is mounted 10 m, the thermometer 1 .5 m, above the snow surface. 

Figure 50 is a sununary of wind and temperature conditi ons for 1975. The 

almost complete absence of winds from the west is the single most striking 

feature. The dominant wind direction is easterly; for 89% of the time the 

wind is between north and east inclusive. The strongest wind speed, about 

7.7 ms- 1 , is associated with northerly winds. The average wind speed for the 

year is 5.0 ms- 1 . The maximum speed for one hour reported during 1975 was 

19.6 ms- 1 , from grid-north on June 19. The wind was reported as calm only 

0.3% of the hours during the year. 

4.4.6 GMCC Trajectory Program 

The GMCC (air parcel) trajectory program was continued during 1975 with 

the main emphasi s on conversi on of the computer system from the CDC 6600 to 

the IBM 360-195 computer. The data base for the analyzed winds was expanded 

to the NMC 65 x 65 Northern Hemisphere square grid from the earlier 1977 

point grid. Three classes of programs have been developed for the various 

monitoring stations. These include analyzed wind only from the NMC grid , 

observed wind only from the global upper air station network, and analyzedobserved wind combined, each of which can be tailored easily to the requirements of the individual stations. This year backward trajectories were 

computed at various height l evels for Adrigole (Ireland), 10-day, analyzedobserved; Ithaca (NY), 5-day , observed only; and Mauna Loa (Hawaii) , 10-day, 

analyzed only. Figure 51 shows the periods for which trajectories have been 

completed, for these and other stations of interest to the GMCC program. The 

objective for the coming year is to complete trajectory calculations at all 

listed stations except for cases where data are missing (at present, anal yzed 

winds for December 1974), as well as maintaining a current (probably 2 to 3 

month lag in real time) record for each station. Computer programs including 

construction of the data base for Samoa and the South Pole may not be initiated until the latter part of 1976. 

4.5 Solar Radiation Measurements 

4.5.1 Introduction 

The GMCC solar radiation program is involved with or owns over 200 radiation sensors that collect data at a rate of about 9,700,000 data points per 

year. Table 13 sununarizes the overall number and location of the instruments 

71 
F requencyl 11 

D ~. 

Average Wind 

Speed for 

Each Month of 

Year (ms 11 

Jan Feb Mar Apr Jun Jul Aug Sep 

0 

- 400 

- 600 

A ... erage \'.'ind Speed for 

Each 01fect1on nH 1 ~ 

Line AUO\·e 

5 10 15 

F requencvf l I of 

\Vind O.rectton ( ,) 

Bar Graph 

Air Temperature 

For E•ch Month 

of the Year f°CI 

20 

Figure 50. Surface weather data for Amundsen-Scott stati on, South Pole , 1975. 

Frequency (l) ( %) 

Frequency (Z) ( %) 

= Number of occurrences of the event x 100 All observations during year 

Number of occurrences of the event x 100 Observations for given month during year 

by type. Detailed calibration histories and locations of the instruments 

will be published in a NOAA Technical Memorandum sometime during 1976. Since 

the multichannel pyrheliometers have 15 sensors, the water vapor meters have 

2 data channels, and the sunphotome ters have 2 data channels, there are 179 

data channels represented in the table. These together with the cooperative 

measurements total over 200 data channels. 

72 
Adrigole - 1974 

Barrow ~ 

Bermuda 

Ithaca 

Mouno Loo 

~-­~ 

So moo 

South Pole 

Adri gole 1975 

Borrow 

Bermuda 

Ithaca Wl!l///l/I/////~ 

Mounoloo 

Samoa 

South Pole 

~ 

Jan Feb Mor Apr Moy Jun Jul Aug Sept Oct Nov Dec 

Figure 51. Completed GMCC trajectory programs. 

4.5.2 Sampl e Data Outputs 

The foll owing is a brief description of major efforts undertaken in the 

processing and analysis of ~he data. Because of the large body of data 

obtained in 1975 , not all data have been processed. 

HOURLY AND DAILY INTEGRAL COMPUTATIONS , ALL CHANNELS 

Hourly integrals in true solar time were cal culated for all the ICDAS 

data from Mauna Loa for days 189 through 336 , 1975, for each instrument 

channe l. Portions of the data from Barrow and from South Pole have been 

examined in a similar manner. 

Day 262 for MLO is illustrated in Table 14 and is taken as a random 

sample. This was a clear day and the outputs of 16 channels are given and 

identified below the main table. Ce rtain portions of the data have lines 

73 
Table 13. Solar Radiation Instrument Summary 

Type At Field In Boul der Total Acquired 

Stations in 1975 

Pyranome t e r s 26 23 49 11 

Multic hannel 

Pyrheliometers 2 3 5 0 

Pyrheliometers 3 13 16 12 

Water Vapor Meters 1 5 6 5 

Sunphotome t ers 3 7 10 4 

Standard 

Pyrheliometers 0 7 7 0 

drawn t hrough them indicating that the data are invalid for instrumental 

reasons. For example, the pyranometer with the shade disc on channel 17 has 

invalid data for hours 05 through 08 because of tracking errors on the disc. 

Channels 22 , 23 , 26 , 27, and 28 , and probabl y 29 and 30 , are invalid because 

of tracking errors of the multichanne l radiometer. These tracking e rrors can 

be recognized o nly by comparison of channel 22 and 23 data with t he normal 

incide nce pyrheliometer (which is on a separat e tracker) data recorded on 

c hanne l 24 . Such l oss of data is quite common and data for a better-thanaverage d ay are presen ted here. Other data were l ost from intermittent noise 

or spikes in the signal s , tape changes, large amplifier o ffsets, other 

tracking errors, lidar operation , or ICDAS down t ime. Units are in l a ngleys/ 

day except for channels 24 and 25 (the water vapor meter (Fo st er-Foskett 

type ) c h annel s ). 

A few o ther features are also of i nterest. For example, the daily 

integral for the bulb type pyranometer 1825 exceeds that for the model 2 

pyranometer 12616F3 by 2.8% . The ratio of outputs of the t wo instruments is, 

furthermore , not constant during the day, probably ind i cating d i fferences in 

cosine r esponse and temperature response. The OGl pyranometer and the quartz 

pyranometer output r a tios gen e r a lly vary between 0 .70 and 0.75; the RG8 and 

quartz pyranometer output ratios vary between 0.50 and 0.55. These vari ations approximate theoretical values, indicating uncertainties of no more 

than several percent in the instrument calibrations. The same comment 

applies to the good data from t h e mul tichannel radiometer . 

COMPARISON OF EXTRATERRESTRIAL AND MEASURED SOLAR INSOLATION 

Table 1 5 illustrates results for pyranometer 12616F3 for a period of 

e lP.ven days, including day 262 illustrated above. In addition t o hourl y a nd 

daily integrals , information i s provided on the fraction of extraterrestrial 

radiati on received. The values are reasonable as may be seen by l ook i ng at 

hours 11 and 1 2 about true s olar noon. On a clear day the predicated percent 

of transmi ssion i s 86.6% according to theoretical values and the maximum 

74 
Table 14. Sample Print-out of Hourly and Daily Integrals For One Station For One Day 

HOURLY INTEGRALS - SOLAR RADIATION AT HLOITSTI DATE 262 1975 IN LY/HR ANO LY/OAY 

C ALIS RATIONS - 16 125. 930 17 1't3.81t0 18 136. 000 19 130.ltOO 20 5. 21t0 21 155.760 22 153. 610 23 338.61+0 

CALIBRATIONS - 21+ 1. 000 25 1.000 26 137.170 27 162.070 28 11+2.650 29 27 .027 30 72.lt61+ 31 287.092 

CAL. UNITS - HW/CH2/VOLT 

CH/HR 05 06 07 08 09 10 11 12 13 11+ 15 16 17 18 19 DAILY 

16 .1 1 o.8 33.0 51+.6 73.3 86.1 92.2 91.8 81t.3 10. 1 52 .1 3 0. 3 8.3 -.z -.1 687,1+ 

17 cl ,,,, Hui l§u9 2.6 2.9 3,3 3.5 3.7 3,5 3.2 2.6 1.3 -.3 -... ~ 

18 - .1 8.lt 25.3 1+1. 0 55.3 &It. 8 &9.2 &8. 8 &3.1 52. 9 38.8 22.2 5.5 -.3 -.3 511+.5 

19 -.J 6.0 18.lt 30.2 l+D .1 .. , • 0 50.0 lt9. 8 45, 8 38.6 28. J 1 6.3 J.9 -.5 -... 373.2 

20 .o .J 1.1 2.0 2.9 3. 5 J.8 3.9 3.6 2.9 2.0 1.1 .J -.o -.o 21.1+ 

21 2.8 58. 9 80.2 97.6 91.lt 92u 8 8815 8 ... " 9~1! 9!1 8 911 iJ il'!iioJ 51.lt .9 .5 ~ 

22 z.8 59.J 80. 8 88.1 91.9 ,2,a 17ui 8ilul 8lu8 I lei lie& 1iu8 52.0 1. 0 .6 ~ 

Zl z.1 59.Z 80.7 1111..z 91.9 93.3 93.3 92.9 91.6 89. 5 85.lt 11.0 51.6 .1 ... 998.l 

Zit 1.3 18.6 18.8 21. z 22.3 22. 3 22.3 22.J 2 2 .3 2 2. 1 21.8 21.lt 19.6 .3 - . o 256.lt 

25 .6 15.6 17 .6 19.6 20.6 20.6 20.lt 20. It 20.1 1 9. 8 19.2 18.1 13.5 • 0 -.o 226.1 

26 2.6 55.8 71t.3 80.0 83.0 8ilu fl 12ui! 19o1 11h. 111 '1 1&olt ·-~ lt8e 8 . 1 ... ~ 

27 2.a, lt9.3 61.8 65.7 67.7 61u!ii 61f11! •••• '''" ,,. ' &fJ tl '"•l lt3.5 .6 .2 ~ 

28 2.2 37.8 lt5.0 lt7.0 1t8.2 .,.,, t .. ,.. -··· 29 .2 .2 ... .5 .& .6 .6 .6 

Oh' 

.6 .6 

. .,., ' ~~ 

.5 ... 31t,O .z 

.8 

.2 

.5 

.z 

~ 

6.1+ -...J 30 .8 9.0 10.0 10.7 11.2 11. 3 10.9 1 o. 6 10.2 9. 9 9.6 9.0 7.J ... .3 121.2 IJ1 31 -.e 11.lt 32,7 5a,,9 72 .9 86.6 96.1 97.0 87.5 1 z.1 53.7 31. 4 9.6 .1 - .1 706.1+ 

CHN. SERIAL TYPE CAL. FOUND ON COHHENT 

16 12616 GQ • 0791t1 83173 

17 10151 GGGZ2 .06952 1121+69 SHADED BY DISK 

18 10152 GOG1 • 07353 112469 

19 10153 GRG8 • 07669 1121+69 

20 10232 GUV 1.90800 121569 

21 475812 NQ1 • 06350 11071t 

22 1+75813 NQ2 • 061t90 11071t 

23 2119 NIP • 02953 60970 

Zit -o HZD 1.00000 -o 

25 -o H20 1.00000 -o 

26 lt758 NGG22 .07980 11071+ 

27 lt758 NOG1 • 06170 821t71+ BOULDER CAL, ADOPTED 

28 lt758 NRG8 .07610 11071t 

29 4758 Ni .37000 11071+ 

30 1+758 NII .138 00 11074 

31 1825 BULB • 031t83 91662 Nlf S CAL. 
Table 15. Sample Results for One Pyranometer 

HOUPLY INTEGRALS, GLOBAL RADIA TI ON, AND P~RC NT OF ~XlRATERREST~IA L AT HLOlTSTl IN Y/h~ ANO LY/JAY 

CALIBQATION - 16 125.900 CHIH~ 05 C6 C7 t) 8 09 1J 11 12 13 1 .. 15 16 17 B 19 DAILY 

OATE 255 1975 

1& o. o o.o o.o c.a o.o Ii. 0 0. t) 91 ... 35 . 5 72.b 39 . b 33.<: 12. I+ - • a -.2 3J ... 7 

16 o.oo o . oo (j, 00 a.co O, OD o.o c o.oo 82.58 81.81 80 .Sb 57.09 71.t. 7 0 73. 11 17.lt2 :; • (j 0 

DA TE 256 1975 

16 • 1 11.2 33. 5 51t,<J 73.D 115. 6 91. 8 9 1. 4 Sit . 3 71. 1 52 . 7 31.4 9 . 5 -... - .2 69G." 

16 8.15 57 . 66 7 2. ltO 77.lt2 6G. 25 81.53 81.88 83 .12 82.38 80. 7 8 77 .43 12.i.3 56.7J 1 . 64 c. 0 0 

DATE 257 1975 

16 .2 11. 3 31t.1 55 . 9 71t ... 87.6 91t.J 93 . 8 36.6 7J. 3 51t . d 32. 9 10.1 - .o -. 1 7 ;:,9 , 3 

16 20.76 60.31 75.36 80 .51.t 83 .39 65.0lt 85.62 35. ltl+ 81.t. 76 63.57 61 . 11 76. C.2 b2. ll 10.71.t :; • 0 c DATE 258 1975 

16 . 2 11.s 31t.7 56. 7 75 .3 Cid. 6 95. 0 91+. 5 67 . 2 7 3. 5 Slt.9 J2. 3 10 . 1 • 1 - • 0 715.li 

16 10. 06 62.67 n. 10 61. 96 81+ .75 66 . 24 cl7 . J5 8b.31 85 6~ 84 . • 9 0 1. 59 76.65 63. 11 4. 55 J . 0 0 

DATE 259 1975 

16 .1 11. It 34. f> 56.5 75 . 1 80.1 94,3 9 4. 5 cl6. 0 73. G 54 .1 32.0 9 . lt - .1 -.1 7;9.1 

16 41. 41 61.00 76. 58 61.67 84. Sit 85.9u 66 . 12 86.6( 64.65 81+ .as 81.23 76.,)8 62 . 54 24 .57 ,.oo DATE 260 1'H5 

tr. .1 11.1 lit. 0 55 . 8 74.2 56 . 8 93.0 93.l 75.3 44. 0 43.1 26.1 6. 7 • 1 - • 1 b4J. J 

....J 16 9 . 56 60.30 7 5. 6& so. 94 63 . 7'l 81t . 86 65.16 65. bl+ 74.51 51 . 10 b ... 62 61 . 55 lt6. 82 2. 46 J. u 0 

O'I '.lA TE 261 1'175 

16 .2 1C.8 33.2 54.8 73.i:! 86.4 92 . 7 '12. 0 o4.3 7 o. 9 52. 3 3 G. 5 6 . .. -. 2 - • 1 6d9.4 

16 7.t2 57 ,79 73, 77 79.3& 62.59 o4 . SC 85.11 d4 . 81+ 63 .&9 61 . 89 79 . 37 73. 8-3 56. 66 • 0 4 . u c 

DA TE 262 1975 

16 .1 1o.8 33.0 54.6 7 J. 3 65.1 92.2 91. 8 o4.J 7 c. 7 ~2 .1 30.J 6 .3 -. 2 -. 1 667 ... 16 1a . s1 58.69 7 3. 61 79.1+1 62. 95 61+ . 47 d4. lib tilt . 88 Ill+ . 0 '1 62.4 6 T'J, 75 74.09 57 . 52 .o~ 3.oa 

DA TE 263 1975 

16 . 1 10.8 33.2 51+ . 6 73.2 66.1 92.2 9 4. 3 61 .1 56. 5 53.5 2'J. j 7 . d - • 4 -.3 652.:, 

16 6.37 59 .36 71+. 6£> 60.0S 63 . 21 61t .76 tlS.~8 a7 . s .. &1.61 65,70 82. ol2 73.ltl St . &It .o o 0 . ~ u 

OATE 264 1975 

16 . 1 10.7 3J.O Sit . S 72 . 6 85 .3 91.Z 65.0 6J.3 5 o. d 1+1 . 7 21.2 7.6 -.1 -.1 &31.0 

16 11. 61 58. 23 73. 90 7 9 ,47 82. 71+ 81t. G6 6 ... 36 79. lb 63 . 83 69 . 51 65 .18 6t! . 3'+ sa . r.3 • Gu . 0 i: 

DATE 265 197S 

16 .1 1 0. It 32.lt 53.6 11. 7 a r.. I+ 90.6 69.9 61t. 3 0. Li 0 . 0 (j . 0 o.J J. 0 . ~ 51 7.3 

16 7 . 21t 57.27 73.CO 78 .lt6 81. 76 63.46 81t. 01+ 53.67 8 3 . 52 69 .51 6S.16 68.31t 5S.ltJ .o o a . co 
value here is 87.5% with a minimum of 79.16%, perhaps due to clouds during 

part of the hour. Average of all the observations is 84.72%, and for those 

values exceeding 83.87% the average is 85.44%. The agreement between observation and theory is satisfactory indicating there is no serious problem with 

the instrument. An analysis of this type has been performed at Mauna Loa for 

all pyranometer data obtained with instrument 12616F3 between days 189 and 

336, 1975. 

IRRADIANCE VALUES AT SELECTED AIR MASS VALUES 

Mauna Loa irradiance values at selected air mass values have been examined since the beginning of the solar radiation program. Irradiance values 

at 64 selected air mass values for each day through April 1974 are on tape. 

Recently, with the installation of the ICDAS at Mauna Loa and the installation of the CDC6600 computer at Boulder, new programs have been written to 

study these data. 

Table 16 gives a sample program output showing morning, true solar noon 

(TSN), and afternoon irradiance values for the first 11 channels of instruments identified in Table 14. The ratios of the outputs of the instruments 

to those of other selected instruments are also given. For example, the 

ratio 18/16 is the ratio of OGl pyranometer and the quartz pyranometer outputs: 23/21 is the ratio of the NIP output to the output of the first quartz 

channel of the multichannel pyrheliometer which, if the measuring systems 

were perfect, would equal one at all times. The tracking error for the 

multichannel pyrheliometer mentioned in the above description of the hourly 

integrals is again evident in this table about true solar noon and later. 

Irradiances are selected at given air mass values because in the long term 

the data will be selected from the same homogeneous population. 

IRRADIANCE VALUES AT SELECTED AIR MASS VALUES, CORRECTED TO ONE ASTRONOMICAL 

UNIT 

Table 17 lists some typical corrected values for day 262, 1975 , at MLO. 

Such adjustments (a.u.) are necessary to compare corresponding values from 

day to day and from year to year, and to theoretical values which are generally tabulated at one a.u. Air mass value~ 1.34, 2.01, 2.69 , and 3.36 were 

selected following the procedure of Ellis and Pueschel (1971), so that this 

tradition at Mauna Loa would not be broken. 

It is necessary to obtain hard copies of irradiance values before slope 

and turbidity analyses can proceed. This procedure allows the validity of 

the data to be checked which cannot be done by computer. Invalid data may 

arise from tracking errors which the computer cannot distinguish from high 

turbidity values. The cost of the analysis procedures is increased by such 

validation requirements. 

PYRANOMETER OUTPUT PLOTS 

Figure 

through 20) 

identifying 

52 reproduces plots of the pyranometer irradiances (channels 16 

on days 262 and 263 at Mauna Loa. Such plots are vai~ie for 

instrument problems. For example at about 0830 on day 262 there 

77 
Table 16. Sample Ixradiance Values For One Da.y at One Station 

IRRAOIANCl ~ALUE S AT SELECTED AIR HA SSES 

-------------------""-"'O,.__ 1175 OOY•262 TgUE SOLAR NOON•22 16, 

CH/AH 

SLP 

16 

11 

12.2 

F.6 . 217 

-.:0.9&0 

10 . 6 

10f.%J -J.., , 377 

- 7 .211 .Ill 

__, 7L/~1~6 -- ~1~0x6 __ ---'"~••~b 

u 

U/16 

. 2 .. 9 . ZJZ 

5 2 . 708 

-16 .770 

,773 

,<;79 

• 77 J 

,591 

~g~-- . --~ 1 ,..u_;__ _ 

19116 

21 

20/16 

21 

-15. 53.. -2 2 ..... J 

.71? ,7ll 

.5~b , <;TJ 

2. I 12 

~Td 

. OJ2 

. o J .. 

75 1. C'T 

- J t'0.616 1 

3 . 35c-

-1 ~e' 

• OJ I 

• ( 33 

103 •. ,57 -Jo7.~7fJ 

6 

2~ . .. 73 

- .. 5 o lc!'i 

IZbdJ 7 •Cj. 5~ .. 

,tlO_ 

.21z 

1oa .16J • 20 , .. OJ . ,, .. .oJ!l 

2.., "Ll- -zi.. 213 

• 7.H 

. 5d 2 

J . .. 61 

- 1. "lb -. ;JJ I 

,CJ2 

l?JS.ooO 

-J7S.5b7 

5 

7.b 

111 .356 

-63.170 

116.&5'1 

- 11.11 7 

.:tL3 

. 176 

u .~80 

- .. 2.036 

• 775 

._fl ~ 

d t ·1li. - J • • 75 1 • 7 .. J 

J.b5J 

-1 . "'"! 1 

. 0 10 

, uJ Z 

lt 3 1 TSN 

6. 1 ... 6 3,0 1.5 

236,6"" J75 , 33G 769 , 355 l SltS.570 -1727.357 

- 10.220 -125 ... 62 -z;1.032 - lt Olt .&35 

? JO.Z"O 

-11.5% 

. ~ll 

. 1 .. 7 

l o J..,t2 

-s ... 601 

• 775 _ _ ,li_'U _ 

358 . ?77 

15.6~0 

.d?.2 

.1 z" 

z .. 0 .022 -8.,. 137 

.775 

llL 

75...JL5 ___ 6 4" 

- ;2.&1; - o6. 77t • 1 .. 0 • 7 .. 3 

. &67 .b92 

1. 2 d .. 

-l.s2; 

-.031- • OJZ 

11. 8b6 

- .. . 1s" 

;-032 

.OJJ 

7ltl,T37 

-21.ob" 

.~~ 

• 0 91 

50. 12 1 -62 . 613 . 

-21.966 

j _ _ . -- ,_pj6_ -

• 05lt 

s..1.000 115 ... ao3 - -1z95.51s-· 

-11s.037 -302.121 

.760 ., .. , .750 

_ill_l__ _ _ - --

_ fil 3 1" ·171.7~d 

.HS 

. 712 

~~lZ~ 

-z,z . a .... • 721 • 720 

• 12 .. 

22 7 ; ... 25z 03 Jb" IJJ~.J•Cj ,25 ~J l I Z1d . 2•b 55~ 6b0 220 7.010 225., ,oq7 

--==-=--..,,..,.-- J~J~~·~ '=1 __ ~3~~~1~=' 1=0 __ 3~1~~~. z~1 __ 1~s~~" =6-- ~J~ ~" 0 __ ~s~ 0~~2 __ ~6~6=6~. oo~--=5~"~·"a~2=-----,,..-~ 

2Z/21 l.G "" J . t(• l . J}.. 1. 10 .. 1. c~ 5 1.0G5 1.006 1. JOJ .98 .. 

ZJ 

23/21 

25 

25124 

2& 

26/21 

?11Z: 

1.o r q 1. ~c" 1. 00~ 1. ~o ~ 1. 00' 1. ao ~ 1.0 0 3 . 'l91 

7l.b , 2 .... ., 

-J 2" . 0£ ~ 

• '1'1"' 

l ·>L . 1' 1 

-: 4~ 5 

l?O ,J17 

- , ... 2 f,:. 

7 I 0 . 5 ' i 

· JI0 .1 37 

~'-b 

o; b. 1t J<o ,. 

-t. ':llCi ·"'· "' • 0 ~ 1 

• ~ t J 

117•.3.11 

-101 . 1r2 

• se.., 

177 . ~, 

-t ~ . '.'.'.., 1 

JLt. . t11.t.S 

• 11 ' .Hu • 1. 7 

, f , •• 

., ... . ,.,,.. -1t> :.. . ... .s7 

• .,c. ; 

O. ~"" 

-33• . • 7 4 ( 

.. -7 ·• 

• ) 7 l 

JOJl.l Ol' 

-l71 .1 22 

• 'j J7 

• ld O 

3•, .. . Ct 

- 1 .. .~~' 

2~ 3 ·""' os 1~ & 

• .,~ 7 

.7 ZJ 

JTT . 2 -1 , 

-153.o 7o 

.... 1 

i<; • • 7 2 d 

- 12 1.ol o 

. o6l+ 

. Ju2 

o l 6 . t..Z o 

-t.ZG. 02 

. ''" • ,~2 

'0? . l 'I>l 

-1 ilj . , 7 2 

< zr, . J~ 1 

11~ . Jh 

• 05 1 

• 1; ' 

11J . 1oq 

-.o.,.ar - · Jlfl 

• , .. J 

• M . 7JJ 

-'!'l4 /5 

• 5 J 

• o't '+ 

l Zob . 0 11 

- 4 2 ... 5~2 

. '1-,0 

,~ ... b~Ct 

-1.J. 227 

J Id . • l& -1!2 . 1 0 1 

.oe~ 

• 1 o I 

1210 . !., .. -4. 1. ~0 l 

• ~J l 

• JJ7 

101 .~ . .... q 

-jlj ~.JtJ 

• o7d 

• o2~ 

1 54b ... b J 

-5b.d55 

• ~ 1b 

422 b~6 

-loZ.tlJ 

JdJ . 412 · IJl.JH 

• 10 7 

. o1J 

1 """ . ao ~ -•~7 3o7 

• • ll 

• ,3 J 

1 25 1. 'q 1 

·ltb. 2&.; 

. o01 

. d 02 

21o7 . o2J 

-661.,25 

,qq7 

I . 00 '> 

5 JJ . JJ5 

-1 0.0~& 

·~6 H .. 

-l5b.o4 6 

?O ZZ , .. I 'l 

· 6 1o.IZJ 

• • 22 

d 2 7 

1711.527 

· 5 11.o32 

. 780 

• 770 

2 240 . <I 

-575,olil 

d99 

1.056 

5 6 ... 6 .. 5 

-1 ..... 065 

S16.J51 -12~ .l b7 

20 3 ... 31'> 

-50 9 .1 36 

• o J 

1 077 . 572 

31d 1~C 

• 7~5 

• 731 

- 171 6. 028 

1.011 

- "1 5 . 750 

oilZ 

- 1 .. 91 .ol7 

- 11 58 .732 

.7 22 

Note: Values are in mWcm-2• For each channel, the upper values are for 

morning and the lower values are for afternoon. 

is evidence that tracking on the disc shading the GG22 pyranometer was 

corrected. The pl ot for day 263 shows t hat the pyranometer was not shaded at 

all. The tabulated daily integrals in watts m- 2 for each channe l are shown 

along the bottom. One langley per day= 0.484468 Wrn-2 • 

LANGLEY PLOT SLOPE AND INTERCEPT VALUES FOR ALL CHANNELS 

Lanqley plots for all the output channels at Mauna Loa were derived for 

several days. The objective of this program was: 1 ) To determine values of 

aerosol opti cal depth using the reference channel of the water vapor meter. 

2) To determine if both the pyranometers and pyrheliometers were calibrated 

78 
Table 17. Sample Irradiance Values , Adjusted to 1 a.u., For One Day at One 

S tation 

CH/AH ~& 

.16 . 1&.7 85. 

16.378 

17 . 16 .1 20 11+. 51J 

17/16 . %0 

• 866 

u 12. 995 

11 ... 56 

U/1 & , 77<+ 

. 6'l'l 

19 :2. '+1& 

11. 2 76 

19/U • 7'"' • & ,9 

.2, . 5 19 

• 5 !5 

20/1& . ?31 

• (; JJ 

21 75.<+1 5 

...• _ lo Z'+'+ 

21121 .~;o 

1. ( (:J 

22 79. &f.9 

1 , '+ 29 

2Z/21 1. ; 1& 

1. 1 '+9 

ZJ .JU, : 61 

5~9 

23/21 1. '~'+ 

- . .. . '.! 

2\ 2& .1 8 7 

-Z<+. 92'+ 

2'+/25 11 ~ 

1. z~z 

25 23. <+ Z<+ 

I 9 , 7 45 

.25/25 lo'.. L 

1.; '- ~ 

2 . &9 

zz. 11 ii 2 2. ( iJ7 

21 . :: <+& 

19. 71+9 

• 952 

• 597 

17.!U 

15. 76 J 

• 77 4 

• 71& 

1 &. 5<+<+ 

15. ~6 1 

• <+~ 

. n 1 

• 7( 3 

• 7'+ 7 

• ;32 

. : :!1.t 

~~ .11 5 

_. 1. 265 

1. Uv: 1. ,: ,j 

bl. . 72.:? 

1. 41+9 1. ; 1 'J 

1 . 11+:, 

_66. 51+ . 

• 756 

1. :<+ ;. 

.. ~9~ 

2 &. 131 

25.17 5 

1.1.~l 

1 . , .. : 

2::: . ;3.., 

2 • 2CJ ~ 

.1 1 . j: 1. • . 

Soo IDENTIFYING LI ST OF INST ~U NT S ON INTEGRA L OUTPUT SHEETS 

HLO 1 9 75 OO Y=2&J TRUE SOLAR NOON=2216, 

31, 5<tl _ 51 ... 532. •• &.<+ ,.229. _ 

31.371 51 .325 6 7. 0 31 

JO , J 5 7 

28. 7<+6 

.953 

.916 

Z<+, 1 2 I ~2 . 8<+J 

• 7&5 

.7 28 

23 . 28'+ 

22 . 57; 

• 7 33 

• 719 

1. 0 .. 7 

1.1 26 

• QJJ 

. CJ6 

:19.398 

1. 30 1 

1. G: J 

., .. . 1 92 

1. '+b9 

1. J 2( 

1.1 z9 

_'1,l ,J 51 

. 7H 

1. 45 

• 539 

25 . 89: 

Z5.<+J1 

1 . .. 'J 1.217 

23 8~5 

~C. H5 

1 . ~ : :. 

1. ~; ... 

't9o '+95 

.. ' · 17 ~ • i60 

.•• 93.L 

39 . '+3 5 

J n, 2 J & 

• 7 6& 

• 7 'tf.t 

H.11+: 

37 . ; 2& 

• 7 <+J 

, 121 

1.~J. 

1 . 973 

• ~ 36 

• . 3' 

95 • • 55 

1 . 35 l l . .. ) J 

1 . - J. 

97.<SJ 

1 . ,, .. 6 

1. , 23 

1 . 1 H 

1w l. • 't) J 

• ~ 83 

1. 6 7 

... J3 

25 . 0:6~ 

25. 77~ 

1 • • &5 

1. 15~ 

2<+ • • J2 

z<. z >o 1 •• 0; 

• • J l 

&1.992. 

63. 6 '+8 

• 9&5 

~.95-l 

'+d. c 93 

5J . 2 e9 

.H9 

• 7 50 

.. 7 . 5 75 

<+ 8 . 931 

• 7<+1 

• 7 30 

2. J 7'+ 

2 . 6~ 2 

• :: 37 

• • 39 

13 . 827 

lo 35'+ 

l o 0) J 1 . ~ ,c 

% . 0 7& 

1 . 5<+ 8 

1. • Z<+ 1. HJ 

1 ; .. . 1 ~ z • <+59 

1. 11& 

• J 39 

25 . 2&2 

lb • • <+5 

1. ; 55 

1 . 1 68 

ZJ,&11 

zz .3:3 1. u j\, 

1 ••. J 

81,.5't8 . 

85 .838 

7 8 , SC Z 75 . 1<+~ 

• 963 

_ .._il_82 

&1.&72 

&5 . :i&8 

• 75& 

• 758 

59. 583 

&2 . 68 3 

• 1 JC, 

,73.; 

J,1 J5 

3 ,393 

.~JO 

. j 't \1 

86. 90 2 

2_. 1} 80 

1.000 

J~O 

88. 781 

2 .32 & 

1 • • 22 

1.11 8 

iw1 . s5 z 

.525 

1. 2'+1 

J 252 

25 .1&5 

2 3 "27 

1. j50 

1 . 158 

23 . 9 71 

1 9 . i82 

1 . Ou~ 

1, )~ r 

, dO 

89 . &19 

74. 318 

, 963 

- 916 

1. ol93 

. 916 

• 755 

.75 1 

b 7. 853 

58 .'+% 

.729 . 121 

3.679 

3 . 372 

• 0 <+O 

• 0 <+2 

7c, .178 

1.&G1 

1. 00 0 

1. oou 

76.256 

1. 832 

1.J28 

1. 1 lo'+ 

1"8 .98 0 

. 958 

1. 469 

,5 99 

llo . 902 

17.<+99 

1 .... 9 

1 ol'+Z 

23. 73 2 

15 .323 

l. 0 liO 

l . J: J 

.70 TSN 

1u_. 775 _ a.a. 99J_ 

111.083 

.1JJ,Z&1 

10&.188 

.958 

----'-~6 

!C.975 

83.103 .751 

• 71t8 

78,21o0 

79. 776 

• 726 

.718 

'to!t88 

... &92 

• 0'+2 

, )C,2 

5 7. C15 c,~.DlZ 

1. 000 

lo ~ Ou 

5 8. 993 

<+&. 081 

1. 03 5 

1 . 01+7 

10 9. 9'o8 

107. 0 <+6 

1. 92 8 

2. <+J2 

Z<+.7 27 

2<+. 7G<t 

1. or.o 

1.10& 

Z3,J25 

22. 339 

1. J Ou 

1 . 0 00 

.958 

81.911 

,752 

79.203 

.121 

• 0<+2 

<+9.130 

51. 1 6 1 

1. 0 Col 

H9.111 

2.22 1 

Zit , 610 

22.925 

26 ~J3 -77 . '>oo d~ .1 01o 00,39; ,,, 252 81o. Z89 _ 75,z2c, &C. 981 !ilo ,075 

1.37<+ 1. 4<+9 1.525 ~. 77 1 .&11 2 , J 47 1.7 85 <+ 9 .JJ<+ 

26121 , q!5 , 0 3., ,c;3: , 9 3 ; , 3c,1 d7 0 1. a 11+ 1 . H o 1.11; 1 

-1....L.5.. ___ 1..a..J...,.2_ __ .1 ,.17 2_ -1..1.61. __ l...1 9~ __ __l ol.Z..8.- _ lo.ll5 J ,121 

Note: Values are in mWcm-2 • For each channel, the upper values are for 

morning and the lower values are for afternoon. 

on the same radiation scale. 3) To determine if the procedure of Ellis and 

Pueschel (1971) for determining turbidity could be treated in a more general 

manner. 4) To determine if total precipitable water vapor amounts could be 

found by using the more general procedure. 

Theoretical considerations indicate that all of the above objectives can 

be met but the present data are too noisy to yield meaningful results. Measured aerosol optical depths are small and often negative because of measurement inaccuracies. Langley plot intercepts obtained with pyranometers are 

7% to 10\ higher than those obtained with pyrheliometers, indicating that 

calibration problems are not serious although problems at the 1% to 2% level 

are not eliminated. The slope uncertainties are greater than those given by 

79 
SC ;..~ q 1u: p .· :o·; . 'h.C :'S 

::v:2'2 s:. ~ ••::.-::·. - ·.: ·s : :' =205 

Figure 52. Pyranometer-produced plots of irradiance in mWcm-2 . 

Ellis and Pueschel but more easily interpretable in terms of total optical 

depth because of higher resolution type measurements. Total precipitable 

water vapor amounts have uncertainties of at least ±3 nun. This technique of 

deriving Langley plots will be further investigated and refined during 1976. 

ANGSTROM TURBIDITY COEFFICIENTS 

Analysis showed that deviations of Angstrom turbidity coeffic ients from 

the multichannel radiometer are not possible with the given instrument calibration constants. A similar conclusion was reached recently by G. D. 

Robinson (1976) . 

4.5.3 International Pyrheliometric Comparison, Davos, Switzerland 

GMCC participated in the International Pyrheliometric Comparison DI as 

part of the NOAA contingent from October 6 to October 24 , 1975. Two GMCC 

instruments were used: Angstrom pyrheliometer ~10180 and Eppley-Kendall 

radiometer 12843. Both instruments were also used in pre-Davos and postDavos comparisons in Boulder and Kl0180 also in the Table Mountain Comparison 

of 1972. 

The ratios of the response of these instruments to instruments representing the Kendall radiometer scale are listed below: 

Place/Date 0 Al0180 EK 12843 Ref. instrument 

Table Mtn. , Oct. , 1972 0.9741 ------ PACRAD 2 

Boulder, Aug. , 1975 o. 97 26 o. 9996 TMI-67502 

Davos, Oct., 1975 o. 9702 0.9999 TMI-67502 

Boulder, Jan. , 1976 0.9727 1.0004 TMI-67502 

The ratio of TMI-67502 to the reference PACRAD at Davos is 0,9997 . 

80 
The comparisons indicate both Al0180 and EK 12843 have remained stable 

during the series of comparisons and serve to tie our instruments to the 

international standards and meteorological radiation scales. 

4.5.4 Water Vapor Meters 

In 1973, development of five water vapor meters was started by the High 

Altitude Observatory, NCAR, at the request of GMCC. The purpose of the water 

vapor meter measurements will be to provide information on, 1, the daily and 

seasonal variations in total precipitable water; 2, the correlation between 

total precipitable water and measurements of direct, diffuse, and global 

radiati on; 3, the correlation between total precipitable water and turbidity; 

and, in conjunction with pyroelectric turbidity meter observations described 

elsewhere , the wavel ength dependence of the direct radiation, the internal 

consi stency of the measurements, the residual absorption due to dust, and 

causes of t he seasonal and perhaps long-term trends of transmission of the 

atmosphere and of the solar constant. 

4.5.5 Miscellaneous Topics 

CALCULATION OF THEORETICAL RADIATION CLIMATOLOGIES FOR ALL GMCC STATIONS 

Expected insolation values in lyday- 1 and wm-2 for each day of the year , 

for each station and pyranometer, were calculated a l ong with other components 

of the solar radiation budget, terrestrial radiation budget , and meridional 

mean climatology. The purpose of these calculations was to check on the 

performance of the pyranometers and ICDAS so that any obvious errors in the 

data collection could be easily and quickly corrected . 

The calculation techniques are being published elsewhere (Hoyt, 1976 ) . 

A sample of the output for Boulder is illustrated in Table 18. The columns 

in t he upper half give the following information: 1) the day of the year, 

2) the daily total extraterrestrial solar irradiance on a horizontal surface 

at the top of the atmosphere, 3) the daily total absorption by water vapor , 

4) the sum of the daily total absorptions by ozone, carbon dioxide, and 

oxygen , 5) the dail y total dust absorption, 6) the sum of the previous three 

columns , 7) the daily total direct irradiance, 8 ) the daily total diffuse 

irradiance , 9) the daily total global irradiance, and 10) the ratio of the 

global irradiance to the extraterrestrial irradiance. In the lower half are 

given 1) the day of the year repeated, 2) the daily total gl obal irradiance 

for wavelengths greater than 530 nm (A>530 nm), 3) the daily total absorption 

by water vapor, 4) the same for A>695 nm, 5) the daily total normal incidence 

irradiance, 6) the daily total irradiance absorbed at the Earth 's s urface 

from the diffuse component, 7) the direct component, 8) the global radiation, 

9) the total daily radiation reflected to space at the top of the atmosphere, 

and 10) the total daily radiation absorbed in the Earth ' s atmosphere and at 

the Earth's surface. 

These tables have already proved useful to the solar radiation program 

by indicating errors in the values of the calibration constants placed in the 

ICDAS accidently. 

81 
Table 18. Sample o f Radiation Climatology Data 

SULA~ k .A I) I A T IC ' l<ES Li LTS AT 

OVL.DE~ 1 CQLUa l 11 TEG IHL VAL. Vt:S 2 ,:: Ll I.' NC • 7 

! NSflLAT lf1r• .I I" s I "T !; IJR F ACf:. ~f:.FL I TOTAL 

DAY OG 1 ~ l.2 "'G~ :" ' ;ql"' .AL [' 1 . ') IF~• GL Qt; AL T(l l-' ·~s. 

1 I 1a 3. 1 2fi G,1 23~,A Q\7,4 21 (I I1 q 1 •LI 3 1) \I 1J 231>,tl "40. 8 

2. }115 I 0 2 8 \,b 2.HI, \ q 21 • 3 2 I I , 5 QI, 5 303, I) 238,0 41J2,l 

.la l<i7,o 2tl3ol 239,') 92~.s .213. 0 ~1.1 J Qjj I b 239.2 

""" .1 ". l"Q·~ 2ss.1 2 0 I 1 3 qzQ.q 2 \ (j.,., q l , I:; 3 ll h. IJ 21J {I, b 1145,q 

5. 351 ·" 287,J 2 4J, o 4 JU 1 I- 21 ". u 92, 0 308,IJ 2a1,9 4118 1 () 

ba 15".2 289,2 2 r.1l.l ,e 9 .l'/,9 21':.2 92.2 31015 2111.1 1,150 o l 

1. JSb,8 cq 1 • u 2 1J '3,7 4U~ 1 2 221 •• ?. Q2,5 31217 21J4 I 8 452,7 

8, 359,7 j>9J,7 2 uA 0 II- ClS r·,'1 ?2?.. 3 9 ?. ,7 3t'5. o 21Jb,1J 115~.l 

9, 302,1 2911,t! 25 1) I q q51'1 I 7 2z_u,i. 92,9 311.s 2Qt11l 4S8 1(l 

1 (). 31'.>S,B 29"· ~ 2s ~.? Q l-) 2,i. 220,Q Q3,2 32 0 1\ 21J9,9 libr) 1 8 

11 • Jo9. 1 3 (\ 1. IJ 255,1) l/t'IQ. 3 ~., 143. I.I 322 ,8 251 . 8 4b},8 

12. 37 CI 5 3 QIJ .J 2~A, ~ 415,11 231. 0 9 3,7 J2S,n C!5} 19 4f'l&,9 

13. 37b. 1 :s o1.2 2 0 0 ,f- 9132 ,7 2 .5 u. I:> QIJ ~ (L HH,5 25b, O 117 0 o1 

1u, 379,A 31 1~ . 2 ~ 7 2 3 7. 3 .... • , • b 2st1,2 u 73 .s 

151 }83,7 3, ~ ~(j ,) - 2h 0 1b ~ 7" , 

1 b. 38 7 • ., ~t.2,11 

1 7. 

SOLAR FU l>l AT JO"I Rf S UL TS AT 

liU.Ul.Df. R, CULIJ . l ri lE.G r< AL . YAL L' ES . - .. .2.. f jjfi. ·~ c I .7 

EXT, AT MU S~~E l<' lC f. ~Pl ! (1•• l"-SlJLAT rJ • 

. .OA y l~SUL • h2 i] r:l NQI-{ !.: '.J S T .tl'T AL lH~ECT OH F • GL .,~ L FIATlO 

1 • t-11,b 77.5 51:-,3 c; • s t3Q,J 31J 7. ~ 151. 3 uqq, 1 • 737 

2. bt! 0. l 77. IJ 5 I, 0 II ., • 5 1 3q. (j 35 0 ,1 IS 1o5 501,b • 737 ---. . 1 .. . . .btllol . 7.7. I/, Sb.S ._s, s -139. y . . ....152. b .1s1. a 50<1. jj • 13B ". b~h.5 11. /J 5 ~ 1 I> s,r, \JCl,5 355,l 1 52, I) 1) 07,3 ,73q 

5. btlq,q 7 7." s~.1 c; • 5 13 q." 358,2 152.3 510,b , 7'10 

ba . . b9lob - .. 77. I.I. 5o,9 .s.s 13'i.a 8 . .lbl.l 152.7 514,0 .741 

1. b97,5 11. '5 5 7. ') "." 1ti 0 . 0 lb <I . b I 5 l, I 517. 7 • 7" 2 

8, 70 ! , 7 77.~ 51. (> s.o JU CJ , 'J 5b b . 1 1':)J,5 52 1 . b • 7llJ 

9 • . . 1Cib.1 77.b ~7.l ... 4o . 1140.5 .J11.e 1s1,q 525.b • 711U 

1 0. 110.~ 77,7 ';7. c; 5,o J IJ (J • "I 315,i, 1su,3 529,9 0 1Ub 

I 1 o 11s.1 77, I'. 57,7 r; • ~ 1 " I , fl 37~,7 1':1LJ,7 53u,a I 7117 - -- -12a no.s 77.9 57,8 .5. b . 1.-i.'1. 3 383,'1 155. t 53911 . • 7118 

11. 7?.f>.1 711. (• . •) 5.,., 1 IJ I , Ii 51! a• IJ 15Sob ljlJIJ,O • 7 '19 

1 ". 131. 7 7 ti, I ~.2 5 . 6 t 4 I , ~ 3q3, o 1s,,.1 SU9, o ,750 .. -· 15. 737 .s . l B • ! 58 ,3 - s. !l - .Hl2o2 .. 39 7. 7. 15b .s ssu.1 • 752 

1 b. 743,5 H'·. 7 ti . 5 ~.n 1u2. ~ IJ 0 1 • ~ 157,f) i;,59,4 ,752 

1 7. 7U9 0 A 7q,2 5 Ii . 7 5!7 1"3. ~ ~ 0 5. q 15tt. 7 5&11,7 ,751 18~ zso."' - -. .. ,, - 'i. Jl l 0 .3 . 159.9 570.l • 751.1 

1 Q 8 . 1b1 • 2 576,0 ,755 . . , . LJ Sli 1, 9 .75b . - 0 _,,., 

Note: Units are langl eys/day. 

82 
PYROELECTRIC TURBIDITY METER 

During 1975 the feasibility of developing turbidity meters using pyroelectric detectors was investigated. Computer programs were written and a 

trial run was made on a prototype instrument, developed by NBS for laser 

calorimetry, to check on the suitability of such instruments f or GMCC use. 

Since the time that initial work on this project was started, electrically 

calibrated pyroelectric detectors have become commercially available. 

OTHER SUPPORTING COMPUTER CALCULATIONS 

In addition to the computer programs directly concerned with data processing and analysis (sec. 4.5.2) and with the radiation climatology, several 

other supporting programs have been prepared. Chief among these are: 

1) Computations of Rayleigh optical depths versus wavelength using the 

latest value for the depolarization factor given by Rudder and Bach (1968) 

for N2. 2) Computations of the air mass values using the U.S . Standard 

Atmosphere 1962 up to 90 km for 0.40, 0.45, 0.50, 0.55, and 1. 06 μm wavelengths. Comparison with tabulations by Kasten (1964) showed agreement to 

within 1 part in 10 , 000 at nearly all solar zenith angles. 3) Computations 

of the air mass values for the beginning of each minute of every day for 

Mauna Loa , Barrow, and Boulder. (These tabulations are very useful for hand 

checking the results of our data and for the sunphotometer calculations.) 

ACQUISITION OF SOLAR TRACKER 

A solar tracker was acquired from Carson Astronomical Instruments , Inc. 

in 1975. It has a hexagonal spar for the mounting of more than one instrument and has a tracking accuracy of better than 1 arc minute. A dome for 

housing this instrument is being built. Modifications to the original instrument have included a new holder for the solar tracking head and a holder for 

a pyranometer for pyrheliometer intercomparisons which are p lanned. 

4.6 Precipitation Chemistry Measurements 

The analysis of precipitation for its chemical constituents has been a 

part of scientific investigation for over 200 years. Atmospheric chemistry, 

meteorology, geochemistry, limnology, agriculture, and ecology are among the 

disciplines that have recognized t he importance of understanding the c hemistry of precipitation. Scientists in ·these various fields have conducted a 

multitude of precipitation chemistry studies. 

Although all this work forms a solid basis of reference for global and 

regional monitoring, it is important to define the methods, techniques, and 

purpose of precipitation chemistry to answer a basic que.stion in terms of the 

GMCC program, i.e., how does a particular measurement at a baseline site contribute to our monitoring of climatic change? To answer this question one 

83 
must realize that precipitation chemistry data can be viewed in two ways. 

First, the precipitation that is collected represents complex processes in 

the atmosphere which include condensation of water on particles, capture of 

particles and gases in clouds, coagulation of cloud droplets to form rain, 

and finally the scavenging of gases and particles below a cloud. An ice 

phase may also be involved to complicate the picture. Actual "climatic 

changes" may participate in each of these processes in the atmosphere. By 

measurement of sulfate, nitrate, and other constituents over a long period of 

time the gross integrated index of these different chemicals can point to 

trends. But even if trends are detected, meteorological and other related 

data must be used in interpreting the results and subsequently relating these 

to the concept of "climate" . 

Thus, precipitation chemistry data can be used as an index of compounds 

that may influence the climate--so2 , sulfate aerosols, ammonia, chloride, and 

others. An improved solution would be to measure these gases and aerosols 

directly in and out of clouds at several levels in the atmosphere for concentration, chemical composition, size distribution, and other pertinent 

parameters. Such measurements are not yet practical in monitoring programs 

and can be obtained only on a research basis with newly developed techniques. 

Thus, the gross measurements provided by precipitation chemistry must suffice 

until we have more sophisticated, economical, and direct methods of sampling. 

A second kind of information that can be gathered from precipitation 

chemistry concerns the deposition of materials to the Earth's surface. This 

information becomes extremely important in evaluating the Earth's geochemical 

and biological systems. Knowledge of the chemical cycles at the atmosphereEarth interface will be helpful in recognizing changes in the biosphere. 

Such biological changes may eventually have indirect climatic effects. 

A case in point is the increase in acidity of precipitation both in the 

northeastern United States and Scandinavia which has been postulated to be 

caused by an increase in ·nitric oxide and sulfur dioxide in the air. Reduced 

tree growth and decreasing fish population are a direct consequence of this 

anthropogenic and regional phenomenon. An even more subtle problem could be 

the long term synergistic effects caused by this change in precipitation 

composition. Such trends in precipitation chemistry make it imperative to 

establish baseline measurements in pristine areas such as those around the 

present GMCC observatories. These data would show to what extent these 

regional trends may have expanded to a global scale. 

4 .6. l New Precipitation Chemistry Activities in 1975 

Because the World Meteorological Organization (WMO) has established precipitation chemistry as one of the required programs at baseline and regional 

stations, the WMO sponsored an expert meeting on wet and dry deposition 

(WADEM) in November 1975 (Kronebach, 1975). The purpose of this meeting was 

to coordinate international studies of precipitation chemistry. In the final 

report, the participating scientists suggested preferred sampling techniques, 

analysis procedures and data processing methods. The recommendations will be 

used to revise WMO Manual No. 299 "WMO Operations Manual for Sampling and 

84 
Analysis Techniques for Chemical Constituents in Air and Precipitation. " 

Such coordination and standard setting has become imperative because of the 

great interest expressed by Australia, Kenya, Argentina and other countries 

in establishing regional and baseline sites. 

Besides participating in the WMO-Expert meeting, Dr. J. Miller of the 

GMCC staff participated in the unilateral exchange program under the US-USSR 

agreement on cooperation in the field of environmental protection. The 

purpose of his 4-week visit to the Soviet Union was twofold: First, to 

investigate the work being done in the USSR in geophysical monitoring, especially precipitation chemistry; second , to find areas of cooperation between 

the US and the USSR on the "effects of pollution on climate". The visit was 

successful in that Miller was able to work with Drs. Selezneva and Petrenchuk, two of the leading scientists in precipitation chemistry. It is hoped 

that through this exchange program Soviet scientists will visit one of the 

GMCC facilities in the future. 

Nationally, the year 1975 was one of active scientific interest in precipitation chemistry. This interest was demonstrated in the Acid Rain Symposium where over 100 papers were presented. One of the most important 

studies to evolve in the last year has been the Cornell University intercomparison study jointly supported by an Environmental Research Laboratories 

(NOAA) grant and GMCC. Under this grant, Prof. Gene Likens and Dr. James 

Galloway have made significant contributions to establishing a scientific basis for the collection of precipitation and its analysis. 

In this study precipitation was collected by several methods using apparatus of different designs. These differing methods and designs were investigated to determine which gives the most representative sample of precipitation for the determination of some 25 chemical parameters. The experimental site in Ithaca, New York, has 22 collectors of 10 different designs 

(Fig. 53) that collected in bulk (wet and dry deposition collected together), 

wet only (only rain and snow) and wet/dry (wet and dry deposition collected 

separately) . In every sampling period, which varies from one day to one 

month, depending on the time variable being tested, the samples are analyzed 

for the following: conductivity, pH, Ca, Mg, Na, K, NH4 , N03, Ntotal' Si04, 

P04 , Ptotal' Cl , S04, DOC , Zn, Cu, Mn, Fe , Al, Ni, Cd, Pb, Ag , DDT, DOE, 

Dieldrin and PCB's. 

Major conclusions of this study are: 

a. Precipitation ~amples must exclude dry deposition if accurate 

information on the chemical content of precipitation is required. 

b. Substantial contamination results when glass and plastic coll ectors 

are used to sample precipitation for inorganic and organic components, respectively. 

c. The inorganic components of precipitation samples of low pH (3.5-

4. 5) , with the exception of PO~ and Cl, exhibit no significant change in 

concentration when stored at 4°C for a period of eight months. 

85 
Figure 5 3 . Site of Corne ll Un iversity intercomparison of precipitati o n 

coll ection methods. 

d. If quant itative informa tion on the chemical composition is required, 

precipitation samples s hould be collected at intervals no longer than 1 we ek 

if immediate c ollection i s not possi ble (Galloway and Likens, 1976 ) . 

To apply the results of the Corne l l comparison to study of regional wet 

deposition of air pollutants , e specia l ly sulfur, four regional collection 

sites will be e st ablished under a cooperative effort by Battell Northwest and 

NOAA and funded by the Energy Resear ch and Development Admini stration (ERDA), 

Fig. 54. The stations form a "baseline " t hrough the northeast U.S. where 

changing energy r e sources will increase the use of high sulfur fuels in the 

years to come . State Univer sit y of New York (SUNY ) at Albany, Cornell Un i -

versity , Pennsylvania State Universi ty and University of Vi rginia will par -

ticipate in the projec t. It i s hoped that with careful siting, collecti on, 

and analysis, the se stat i ons will produce long-term qual ity precipitati on 

chemistry data especially useful in t he evaluation of environmental changes. 

Another area that has been i nvesti gat ed under modest GMCC fundi ng i s 

that of fog c ollection f or chemical anal ysis. It was found that metal fog 

collectors at Ma una Loa contaminated the samples. To solve this problem, Mr. 

Ray Falconer of SUNY has designed a pl astic fog collector which will be tested at Whiteface, N. Y. in 1976. Event ua lly one will be placed at Mauna Loa 

(Fig. 55) . 

86 
• 

• 

• 

• WMO Regionol Siles 

• NOAA-Bottelle 

Regionol Sites 

• Other Operoting 

Collecting Sites 

87 

Figure 54. Northeast U.S.--

Canada regional network of 

precipitation collection 

stations. 

Figure 55. Plastic fog collector· 

•to be tested at Whiteface , N. Y . , 

in 1976. 
4.6.2 Baseline Precipitation Chemistry 

During 1975, Mauna Loa, Barrow, and Samoa began pH and conductivity 

measurements using pH meters, conductivity bridges, electrodes, chemicals, 

and bulk collectors. It is hoped that the in-situ measurements can be expanded to include sulfate, chloride, and other important i ons. Table 19 is 

an overview of the measurement programs at the three sites. The ERDA program 

is described in Section 5.1.3. The data from the EPA collector are published 

in Atmospheric Turbidity and Precipitation Chemistry Data for the World. 

Table 19. Precipitation Chemistry Measurements at GMCC Baseline Sites 

MAUNA LOA 

Mauna Loa 

GMCC - pH, conductivity (daily, weekly at 

three sites). 

EPA - pH, conductivity, S04., N03, NH4, Cl , 

F, Ca , Cu, Fe, K, Mg, Mn, NA, Ni, 

Pb, Zn, (monthly at MLO). 

ERDA - pH, S04, Cl, N03, Pb, Ni, Ce, V 

(monthly MLO 1976). 

Barrow 

GMCC - pH (weekly at four sites). 

EPA - same as Mauna Loa. 

Samoa 

GMCC - pH measurements to begin in 1976. 

EPA - same as Mauna Loa. 

ERDA - same as Mauna Loa. 

Data of Mauna Loa pH measurements included in GMCC Summary Report 1974 

were those collected in standard rain gauges (metal). New plastic collectors 

have been installed since then at the three main sites--Hilo , Kulani Mauka, 

and Mauna Loa Observatory. Values for the latter half of 1975 are shown in 

Fig. 56. The decrease of pH values with ascent is demonstrated in Fig . 57. 

To show the validity of weekly sampling versus event sampling for pH 

determination, Fig. 58 shows the small difference between the composite weekly collection and the weighted average of all the events for that given week. 

The weighted averaged values are somewhat lower than the composite. 

88 
pH 

"' C1) 

"' 0 

(.) 

5.8 

5.4 

5.0 

4 .6 

4.2 

3.8 

3.4 

8 

6 

0 4 ~ 

C1) 

.0 

E 

:::> 

z 

2 

0 

-- Hilo 

--- Kuloni Mouko (2500 m) 

-·- Mouno Loo (3400 m) 

JUN JUL AUG SEP OCT NOV 

Figure 56. Weekly pH val ues in Hawaii. 

.r'\ 

I \ -- Mouno Loo (3,500m) 

- - Kuloni Mouko (2,500m) 

-··- Hilo (Seo Level) 

I \ 

/ '?\ \ / I \ . / . ., \ 

// .. / · ' ·. 

/ / ' \ 

/ . ' ' 

/ ,/ ' ·. 

//' '' 

DEC 

3.71 - 3.81- 3.91- 4.01 - 4.21- 4.31- 4.41- 4.Sl- 4.61 - 4.71- 4.81- 4.91- 5.01- 5.11-

3.8 3.9 4.0 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 5.0 5.1 5.2 

pH interval 

Figure 57 Histogram of pH values in Hawaii. 

89 
BARROW 

--- Weekly Value 

--- Averaged Event for o Given Week 

2~--~---~- ~--~---~---~--~ 

JUN JUL AUG SEP OCT NOV 0 EC 

Figure 58. Comparison of weekly sampling with event 

sampling at Hilo, Hawaii for pH determination. 

The difficulty of obtaining representative precipitation samples for 

chemical analysis in the Arctic environment i s well known. Conventional collection of representative samples at Barrow is especially difficult, because 

of the small amount of precipitation and the added factor of blowing snow. 

To approach the problem of collection and analysis of precipitation in 

such an environment, a local program of snow collection for pH measurem~nts 

was established. From February 19 to May 19, 1975 , snow was collected weekly 

at four sites, 25 meters north, east, south, and west of the observatory . 

Samples were taken from newly fallen s now and old snow underneath. The ob 

server was careful not to contaminate the sampl e during collection. By standard procedures, pH values were determined on the eight samples. Table 20 

shows the results for the winter season. These data must be considered preliminary since collection and measurement techniques are still to be defined. 

Table 20. pH Values of Snow Measured at Barrow from ~ebruary 19 to 

Ma y 19, 197 5. 

Average 

New Snow 

Old Snow 

Total 

North 

4.80 

5.06 

4.90 

South 

4. 56 

4.89 

4. 72 

90 

East 

4.94 

5 .14 

5.03 

West 

4.95 

5.12 

5.03 
SAMOA 

Special studies of pH in precipitation should begin in 1976. 

4.6 .3 Regional Precipitation Chemistry 

In 1970, a joint program was begun by NOAA and EPA to establish WMO 

regional sites in the United States. Without f orma l site surveys, ten 

National Weather Service (NWS) stations were chosen as regional collection 

points. The only criterion for the choice was that the stations not be in 

urban areas. Table 2 1 and Figure 59 s h ow the sites. Only two, Caribou and 

Huron, had been included in previous Public Health Service networks. 

Table 21. WMO Regional Sites in the United States 

Site Elevation (m) Coordinates WMO ID No. 

Bishop, Calif. 1252 37°22 'N 118°22'W 72480 

Alamosa, Ca lif. 2297 37°27'N 105°52 ' W 72462 

Salem, Ill. 177 38°39 ' N 88°58 ' W 72433 

Caribou , Maine 1 91 47°4l ' N 68°03 ' w 72712 

Meridian, Mass. 94 32°29 ' N 88°45 ' W 72234 

Atlantic City, N.J. 74 35°52 ' N 78°47 'W 724 07 

Pendleton, Oreg. 456 45°4l'N 118° 5 l'W 72688 

Huron, s . Oak. 393 44°25 ' N 105°52 'W 72654 

Victoria, Tex. 36 28°5l'N 96°55 'W 72255 

An informal arrangement was made that NWS would provide the sites a nd 

Air Resources Laboratories would provide eva ~ation of the data. EPA would 

take care of the c hemical analysis of the samples at the Qua lity Assurance 

and Environmental Monitoring Lab. This program has been operated in this 

manner from 1972 to the present. 

The data f r om the regional sites are reported in Atmospheric Turbidity 

and Precipitation Chemistry Data for the World. 

4.6.4 Special Study 

In April 1974, a volunteer program was established in the Was hington, 

D.C. , area to determine pH and precipitation amounts. The network now consists of six collecting sites. The purpose of the network is to test field 

methods of precipitation coll ection that could be transferre d to r e gional and 

91 
---• Pe~ eton 

___ .- - - ' - ' ,' ~ --{ 

I ;--

' I 

\ 

·' Bishop 

' .. ' ' 

' ,' 

----

_ _£11omoso 

• Huron 

, _ 

I 

I 

I 

I 

- • Solem 

,. 

\ 

. - 1 • Meridian 

.-

Figure 59. WMO r egional stations . 

baseline sites which generally have only limited chemistry facilities. The 

pH data should be typical of value s for the northeastern United States. A 

sununary of the 1975 results at the six sites is shown in figure 60 . 

4.6.5 Plans 

Plans for the precipitation chemistry program within GMCC are: 

a. Establishment of in-situ chemical measurements in precipitation at the 

baseline observatories. 

b. Site evaluation by both mul tiple collection at the baseline observatori es 

and meteorol ogical anal ysis using air trajectories. 

c. Replacement of present open-close collectors at both regional and baseline sites with more reliable collectors. 

92 
"' Q) 

"' 0 

(.) 

0 

.... 

Q) 

.0 

E 

~ 

z 

20 

pH Interval 

Figure 60. Histogram of pH values in Washington, D.C. 

(six stations) , 1975. 

93 
5. COOPERATIVE MEASUREMENT PROGRAMS 

This section p rovides an opportunity for the major cooperative program 

investigators to r evi ew their activities at the GMCC Observatories a nd to 

summarize some of their data. A complete listing of the cooperative programs 

i s included in the Tables under Secti on 3. 

5.1 Mauna Loa Observatory 

5.1.l Sunburning Ultraviolet Meter 

Daniel Berger, Principal Investigator 

Temple University 

School of Medi cine/Skin & Cancer Hospital 

The Sunburning Ultraviolet Meter, measures the skin- sunburning effectiveness of sol ar energy. The spectral r esponse of the meter i s similar to the 

skin ' s e ryt hema action spectrum. The data consist of the dose during each 

half hour of sunburning ultraviolet measured throughout the d a y on a horizontal plane. 

It is beli eved that the action spectrum of skin canc er is like t hat of 

sunburn, and the meters have been placed in several locations where data on 

the o ccurrence of skin cancer have been previously gathered : Oakl and , Ft. 

Worth, Minneapolis, Des Moines, Albuquerque , El Paso , Philadelphia , and two 

sites in Australia . The short wavel ength end of the ul travi ol et spectrum, 

which induces s unburn, is strongl y affected by ozone concentration . The 

meter has been install ed i n three locations t hat have Dobson ozone spectrophotome t e r s in order to correlate s unburn effect with ozone changes : Bismarck , Tallahassee , Mauna Loa. Other sites have been c hosen to provide a 

better understanding of the effects of l ati tude , a l titude , and local atmospheric c onditions on the measured parameter: Warsaw, Pol and; Davos, Switzerland; Honeybrook, Pa . 

In 1975 e leve n stations in the United States continued to gather data . 

Two stati o ns in Australia a l so continued their observations . The single 

station in Europe was supplemented b y two others in June. 

Annua l calibrations of each station were made . Annual changes have 

averaged 2% with maximum variations of 7%. 

The 1974 results have been analyzed and p ubl ished by the National Cancer 

Institute Publication DHEW NO (NIH) 76-1029 , "Measurement of UV Radiation in 

the U.S. and Compari sons with Skin Cancer Data ." The conclusi ons o f this 

r eport are applicable to any other single year i n which the stations are 

essentially the same. 

An e xpanded network i s projected for 1976. Si x addi tional stati ons in 

the Western Hemisphere and an addi t i onal station in Europe are p lanned. The 

climatology developed should be useful to a variety of discipl ines inc luding 

epidemiology, biology , and meteorol ogy. 

94 
5.1. 2 Atmospheric Electric Measurements 

William Cobb, Principal Investigator 

Atmospheric Physics and Chemistry 

Laboratory (APCL), NOAA 

In April 1975 , an agreement was reached between GMCC and APCL concerning 

atmospheri c electricity measurements at three of the GMCC stations. The 

agreement calls for APCL to develop and test a measurement system for potential adie ~s , air-Earth current, and conductivity, to install the system at 

Mauna Loa , and to turn the equipment over to the staff for routine operation. 

The purpose of the program is to repeat the measurements made in 1960 and 

again in 1968 in order to detect any secular changes in the atmospheric 

electric climate at the observatory. 

Instruments to measure the potential gradient , the air-Earth current 

density , and the atmospheric e lectrical conductivity were installed at Mauna 

Loa i n October 1975. The potential gradient and air-Earth current sensors 

are the same type as the instruments installed at the South Pole (see Section 

5.3.1). The conductivity sensors, positive and negative , are the same 

"Gerdien" cylindrical condenser systems used in previous MLO measurement 

expeditions. All parameters are monitored by a strip chart recorder and are 

also fed into the station ' s data acquisition system. 

This equipment will be rotated between Mauna Loa, Barrow, and Samoa at 

an interval to be determined by the scientific need so that for each station 

baseline values of the atmospheric electric climate will be developed and 

checked at 5- to 10-year intervals for possible secular changes. No significant data analysis for Mauna Loa has been completed during 1975 . 

5 .1. 3 High Volume Aerosol and Preci pitation Collection Programs 

Herbert L. Volchok, Principal Investigator 

Health and Safety Laboratory (HASL) , ERDA 

The two HASL programs at the GMCC stations have been part of much larger 

moni toring research efforts of this laboratory. One involves high volume , 

conti nuous sampling of the surface air aerosol; the other samples the cations 

i n precipitation by an ion exchange resin column . Both programs have similar 

objectives : the study of spatial and temporal distributions of particular 

stabl e and radioactive species, in air and precipitation respecti vely. 

The precipitation program was initiated at both Barrow and Mauna U:>a in 

1 959. The Mauna Loa station has continued in this study through 1975; Barrow 

essentially discontinued sampling at the end of 1967. The samples from this 

program were analyzed only for Sr-90 . All of the data produced are reported 

quarterl y (Hardy , 1975). The period of 1967 through 1975 for Mauna Loa ha s 

been s ummarized in Table 22. A general description of the program a nd data 

interpretation is published annually (see Volchok, 1975). 

The surface air sampling at Mauna Loa and the South Pol e was actually 

started in the mid-1950s by the Naval Research Laboratory (Lockhart et al., 

1964 , 1965) and continued through 1962. HASL took over the program in 1963, 

95 
ID 

(j\ 

Table 22. Summary of Monthly Fallout Deposition Collections at Mauna Loa Observatoryt .......,.....,.~ %~:r..-:r-::m~. ;ac- ::r-r- .. T, ·..-r· .r~-r--- <Y 't"" -·· - ·...- ... ~- - r .a ;. ~ • .-.. ~ _ s .,.. .r:: ~ 

JAN . 

1967 PRECIPITATION 8 . 81 

SR- 90 0 . 03 

SR-90 CONCENTRATION 0.34 

SR-89/SR- 90 25 . 30 

1968 PRECIPITATION 5 . 08 

SR-90 0 . 01 

SR- 90 CONCENTRATION 0 . 20 

SR-89/SR-90 22 . 00 

1969 PRECIPITATION 

SR-90 

SR- 90 CONCENTRATION 

SR- 89/SR- 90 

13 . 44 

0 . 02 

0 .1 5 

1970 PRECIPITATION 2 . 28 

SR- 90 

SR- 90 CONCENTRATION 

SR- 89/SR- 90 

1971 PRECIPITATION 18 . 11 

SR-90 0 . 02 

SR- 90 CONCENTRATION 0 . 11 

SR-89/SR- 90 5 . 00 

1972 PRECIPITATION 0 . 84 

SR- 90 0 . 10 

SR-90 CONCENTRATION 11. 90 

SR-89/SR-90 

1973 PRECIPITAT ION 

SR- 90 

SR-90 CONCENTRATION 

SR-89/SR- 90 

• 

1974 PRECIPITATION 5 . 66 

SR-90 

SR- 90 CONCENTRATION 

SR- 89/SR- 90 

1975 PRECIPITATION 

SR-90 

SR- 90 CONCENTRATION 

SR-89/SR-90 

Data not available 

*: Zero or trace 

A: Approximate 

9 . 02 

0 . 03 

0 . 33 

B: Lower limit of reported data 

FEB. 

0 . 86 

0 . 01 

1.16 

3 . 91 

2 . 72 

0 . 02 

o. 74 

• 

2.27 

0 . 01 

0 .44 

0 . 64 

0 . 01 

1.56 

1.85 

0 . 02 

1.08 

0 . 51 

• 

0 . 04 

6 .48 

0 . 04 

0 . 62 

MAR. 

10 . 49 

0 . 06 

0 . 57 

6 . 50 

8 . 64 

0 . 05 

0 . 58 

2 . 40 

4 . 60 

0 . 04 

0 . 87 

7 . 70 

0 . 93 

0 . 01 

1.08 

2 . 06 

0 . 02 

0 . 97 

0 . 05C 

1. 98 

* 

C: Proportioned f r om originally consolidated data 

APR . 

5 . 23 

0 .05 

0 . 96 

4 . 80 

11. 25 

0 . 11 

0 . 98 

1. 20 

2 . 46 

0 . 02 

0 . 81 

8 . 50 

3. 28 

0 .11 

3 . 35 

7.01 

0 . 14 

2 . 00 

2 . 08 

0 . 02 

0 . 96 

0 . 08 

0 . 05C 

* 

MAY 

6 . 98 

0 . 04 

0 . 57 

• 

4. 04 

0 . 02 

0 . 50 

1. 65 

0 . 02 

1. 21 

5 . 50 

3 . 63 

0 . 04 

1. 10 

0 . 05 

3. 51 

0 . 02 

0 . 57 

3 . 05 

4 . 83 

0 . 05 

1.04 

JUNE 

5 . 10 

0 . 01 

0 . 20 

• 

4. 0~ 

0 . 05 

1. 24 

0 . 05 

• 

0 . 05 

0 . 79 

0 . 04 

5 . 06 

1. 40 

0 . 01 

0 . 71 

1. 12 

0 . 02 

1. 79 

0 . 76 

* 

JULY 

9 . 30 

0 . 03 

0 . 32 

2 . 41 

0 . 02 

0 . 83 

0 . 64 

0 . 33 

0 . 01 

3. 03 

0 . 02 

3 . 81 

0 . 03 

0 . 79 

4 . 52 

2 . 54 

0 .38 

• 

AUG . 

5 . 87 

0 . 01 

0 . 17 

• 

5 . 43 

0 . 04 

0 . 74 

4 . 20 

0 . 33 

* 

3 . 53 

0 . 01 

0.28 

0 . 28 

• 

0 . 38 

SEP . 

3 . 38 

0 . 01 

0 . 30 

* 

11. 53 

0 . 04 

0 . 35 

4 . 20 

0 . 99 

0 . 02 

2 . 02 

0 . 28 

* 

1.17 

0 . 01 

0 . 85 

1. 65 

* 

3 . 81 

4 . 22C 

OCT . 

4 . 24 

• 

• 

5 . 61 

0 . 01 

0 . 18 

• 

1.45 

0 . 01 

0 . 69 

0 . 91 

• 

• 

4 . 22C 

t : Precipi ta ti on in centimeters 

NOV . 

11. 20 

• 

1.17 

0 . 02 

1. 71 

1. 27 

* 

6 . 48 

• 

0 . 64 

14 . 12 

SR- 90 in Mi lli-Curie/square kilometer 

SR- 90 Concentration in Pico-Curie/liter 

SR- 89/SR-90 = Ratio 

DEC . 

• 

• 

9 . 24 

1. 42 

0 . 01 

0 . 70 

4 . 83 

0 . 02 

0 .41 

0 . 64 

* 

0 . 04 

2 . 54 

CUM . TOTAL 

71. 46 

0 . 25 

72 . 35 

0 . 37 

29 . 75 

0 . 16 

22 . 66 

0 . 20 

36 . 05 

0 . 30 

18. 22 

0 . 26 

28 . 63 

0 . 00 

22 . 59 

0 . 21 

18 . 62 

0 . 07 
but for logistical reasons sampling at the South Pole was terminated and was 

not resumed there until 1970. Sampling started at Barrow in 1975 and is 

scheduled to start at Samoa in 1976. 

In the course of this study, the samples have been analyzed for a variety of radionuclides in response to various stimuli such as timing of the 

nuclear weapons tests, tracer experiments, and accidental releases. Routine 

analysis for e l emental lead was begun in 1966. The current program includes 

analyses for Sr-90, Zr-95, Cs-137 , Cs-144, Pb-210 , plutonium, and stable Pb. 

As in the precipitation program, the data are published quarterly (Volchok et 

al., 1975). Data from Mauna Loa and South Pole for 1974 and 1975 are summarized in Tables 23 and 24. Table 25 summarizes the data from the Barrow 

program which was initiated in September 1975. 

Plans for the immediate future include : (a) providing both the Mauna 

Loa and Samoa sites with instruments to separate wet from dry fallout , {b) 

aerosol sampling at Mauna Loa as a function of wind direction , (c) initiating 

aerosol sampling at Samoa, and (d) increasing the scope of non-nuclear analyses of the sampl es (pH, SO~ , N03, c1; and additional trace metals). These 

program changes will all be effected in 1976. 

5 . 1.4 Tritium Measurements 

Gote Ostlund, Principal Investigator 

Rosenstiel School of Marine and Atmospheric Sciences 

University of Miami 

The Tritium Laboratory of the Rosenstiel School of Marine and Atmospheric Sciences, University of Miami, began atmospheric tritium sampling at 

Mauna Loa Observatory in August 1971. The activity of water vapor and the 

mixing ratio of tritiated water vapor (HTO) are determined , as is the mixing 

ratio of tritium gas (HT). The system is described in Ostlund and Mason 

(1974). First, all the water vapor is absorbed in one "trap" of molecular 

sieve. In a succeedi ng trap , the atmospheric hydrogen species are combusted 

to water which is absorbed in-situ. At Mauna Loa , air is processed at a rate 

of 2 l/min . Two sample runs are made per week, each normally 48 hours long. 

The traps are sent to Miami for extraction and analysis. 

Mauna Loa Observatory serves as the Northern Hemisphere baseline for a 

network of similar sampl ers that includes Fairbanks, Alaska; Miami, Fl a .; and 

Baring Head, New Zealand. The 1975 data from all four stations are shown in 

Fig . 61. The stratosphere contains most of the atmospheric HTO , and the effect of the spring leak on the HTO mixing ratio (very prominent at Fairbanks 

in early summer) is seen to be removed by precipitation and air-sea exchange 

prior to arrival at Mauna Loa Observatory. During 1975, the pulses of HT 

released by underground nuclear test (a major HT source) were below the magnitude needed for unambiguous detection at Mauna Loa Observatory. In previous years, notably 1973, large injections were detected as a step increase in 

the HT mixing ratio. (See Mason and Ostlund, 1974, for a report of that 

event.) 

At the end of 1975, a new HT/HTO sampler was being installed at Mauna 

Loa Observatory. This unit has dual gas trains, which permit separation of 

97 
<.!) 

co 

Table 23 . Surface Air Concentrations of Selected Elemental Species in Mauna Loa, Hawaii 

SURF/>CE AIR CONCENTRATION IN l'ALl\A LCA, HA~All 

JAi\ • Fee. IUR. />PR. MAY JLl'.E JLLY 

CAl'"°A CCPf'/Cl!. l'l 0.032 0.001 0 .138 c . l c? O.Ctt c. 1 es C.C60 

BE- 7 CFCl/CU.l'l l3b.OO 191.CC 247.CO 21? . CC ;c 1. cc IS4. CC 224 . CC 

SR- 9C CFCI /CU. f'l O. b7 2.47 4.2e ? .4 1 ? • e c; ? • le 1. 76 

ZR- 95 CFCI /C U. f'l 14. 30 38. 20 5 2 .8C ? c;. c;c 2c; . IC 1e.6C 32. c;c 

CS-137 CFCI /CU.f'l 0 . 83 3. 65 b . 90 t.e4 1.42 5. l c; 2. 72 

CE-144 CFCl/CU.l'l 13 . 10 47.80 e e .ac E4 . tC e I. IC 52.6( 2'l. I c 

STABLE PBCLG/CL.l'l 8.63 4.29 5 . C4 4.14 ;.t2 ?.22 e. 35 

PB-21C IFCl/Cl!.l'l 7.55 

PL-239 CACl/CL.l'l 15.50 52.60 101.CC 17 .cc lO~.cc e?. c;c 3l. 3C 

SURFACE f>IR CONCENTRATION IN MALNA LOA, HA~f>ll 

J/>I\. FEe. 

GAl'l'A fCPf'/CU . l'l 0 . 053 0.058 

SE- 7 IFCI/Cl!. l'l 199.00 184.00 

SR- 90 IFCI/CU.l'l l. 30 2.06 

ZR- 95 CFCI/Cl!.l'l 28.70 23.10 

CS- 137 I FC I IC L. I' l 2.68 3.44 

CE-144 IFCl/CU.l'l 33 .30 40 . 60 

STABLE PBCLG/CL.l'l 3 . 7b 4 .10 

PB-210 CFCl/CU.l'l 5.28 8 . 97 

PL-239 CACI/CU.I') 30 .60 61. 30 

NG OATA 

ERRORS ARE LE SS TH/>I\ 201 EXCEPT: 

A -ERRCR BETWEEI\ 20t l> l\C 1CC1 

6 -ERRCR GREATE R T~IN lCOX 

M/>R. 

0.044 

231 .0 0 

l . 5 2 

14.70 

2.05 

2S . 3C 

2 . 26 

11 . 3C 

35.20 

APR. MAY 

C.C4~ c .C34 

t<S.CC ?07.CC 

; • 4 c; ; . El 

11. ;c e.?7 

? .u ? • c; c 

LB . ?C ? ? • 3C 

l . ~ c; <. e2 

4C 11.IC 

~c.ec 4E. ~c 

Jll\E 

C. C22 

24<;.CC 

l . 45 

? • 4'l 

2 .21 

15 . l c 

l . 91' 

12.CC 

3C. 3C 

JL LY 

C.Clb 

231 .C C 

l . C1 

l.SlA 

l.3e 

e. l c 

4.42 

1C.5C 

t<;.4C 

CLRll\G 19 74 

ALG. SEF . 

c . 031> 0 . 035 

247 . 00 lb l . oo 

C. 99 o . t6 

l 'l. 70 15.bO 

1. 95 0 . 90 

19. 30 11.80 

lC.10 4.44 

8.42 7. 77 

2c . 10 15.30 

CUlll\G 1975 

ALG. 

C. 013 

259.00 

C.43 

C.3b 

C.59 

3.52 

3.94 

9.71 

e.1>1> 

SE F. 

0 . 010 

271>.00 

0 . 30 

o . 00e 

0.4b 

2. 23 

3.23 

9 . 15 

9 . 261> 

CCT. r-.cv . 

0.033 0 . 04b 

186 .CO 216.CO 

Q.7 1 0 .87 

15.40 2b.40 

l. 12 l . 6 2 

12. 30 20 . 90 

4.51 ?.25 

6 . 60 7.58 

14.80 16 . 70 

CCT. l\CV . 

0.005 0 . 00!1 

188.CO 221> . 00 

0 . 2H 0.25A 

0.44 0.43 

I • l 3 l. 34 

CEC . 

C. C57 

; 1?. cc 

l. 24 

te . 9C 

2 . oe 

2t . 2C 

91 

2 e. c;c 

CEC . 

C. ClG 

24t.CO 

c. 2 3 

0. 56 

1. 2 5 
Table 24. Surf ace Air Concentrations of Select ed Elemental Species in South Pole 

SUR FACE AIR CONCENTRATI ON IN SOLTt- PCLE CLRl l\ G 1974 

JAJI. . FE e. "AR . APR . MA Y JLl\E J LLY ALG. SE F. ((T. JI.C V. CEC . 

GAl'P'A ICPl'/CU.fll 0 . 006 0 .oo l 0 . co l C .CC I C. CC I C. CCl c . c c 1 C. 003 0 . 00 6 0 . 0 12 0 . 021 C . CI? 

BE- 1 CFC! / CU.Ill 146.00 19 7.COA 11 c;.oc E4 .iC SS CA 1S . SC e4 . 2C 62 . 60 B2 . 30 S3 .C O 168 . CO 17 4.CO 

SR- 9C CFCl / CL.l'I 0 .43 0 . 4 1 0 . 2t: C. I < c. 12 c .12 c .11 0.15 0 . 11 0 . 19 0 . 28 C. 42 

ZR- 9 5 CFCl/Ct..:. fll -- -- A -- -- -- C. 85 3.50 6 . 0 4 8.57 10 . 30 (; . 82 

CS-1 3 7 CFCl/CU. fll 0. 6 8 o . 50 C.46 -- C. 3C C.2 4 c. 2!> C. 28 0 . 32 0.39 0 . 4 2A 0. 8(;~ 

CE-144 CFC l/CL. l'l l . 0 6A -- C. 69 A -- C. SIA -- C. 5 1A l. 83 A I • 9 I 3 . 00 4 . 45 4.2 1 

STABLE PBCLG/CL.1'1 0 . 9 3 3 . O I 1. 67 2 . E4 1. c1 1.44 1. 65 3.06 4 . 59 2.1 5 -- 2 . 37 

PB-21 C CFCl/Ct..: . fll -- 0 . 90 C. 54 c . ;4 C. 4? c . t:e C. 6C C. 48 0 . 36 0. 44 0. 11 I . 2 7 

PL-239 CACI /CL . I') 1 . 61 4. 18A 2. 25A 3 . ESA 2 . A ? • l EA l . S2 A 3 . 73A 0 . 35e 2 . 66A 5 . l 2A e.42 

--------------------------------------------------------------------------------------------------------------------------------- SU RFA CE AI R CONCEN TRATION II\ 50L1~ PC LE l~G 1975 l.D 

l.D J A" · FEe . " AR . APR. MAY JL"E J LLY ALG. SEF . CCT. JI.CV • CEC . 

GAl'l'A CCPl'/Cl. .fll 0 . 0 21 o . ooo o .o o: c . cc; c. cc: c. ccc c .cc2 C. 003 0 . 004 0 . 003 

BE- 7 IFCl/Ct..: .f' l 166.00 179 .oo 111 . oc !C S.C C 1c :. cc 72.80 1C4 . CC 11 3 . 00 108 . oo 8 7. 80 

SR- 9C CFCl/Cl: . f'l 0 .42 

ZR- 95 CFCl /C U. f'I 0 . 16 14 . 50 c; . 93 (; . 24 4. (; ~ l . 47A I . e3 A C. 48 1 . 16 0 . 29 A 

C S-1 31 CFC I IC l.. fl I 0 . 15 I . ll 0 . 7; c . 1t ( . 71 C. 2 3 0 . 35 C.42 0 . 32 0 .47 

CE-14 4 IFCl/CL .fll 5.55 10. 30 (; . 97 ~( 7 . cs 2 . 61 3 . 86 2.91 2 . 5 7 1.58 

STAB LE PBILG/ CL. f'I 2 . 11 

PB- 210 IFCl/C U.f'I 1. 76 

PL-2 39 IACl / CU. f' I 13. 10 

--------------------------------------------------------------------------------------------------------------------------------- NG DATA 

ERRORS ARE LESS THAI\ 20t EXCE PT : 

A - ERRCR RE TWEE I\ 20t Al\( 1coi 

B - ERRCP GRE ATER Tt- l~ i coi 
Table 25 . Surface Air Concentrations of Selected Elemental Species in 

Barrow, Alaska During 1975 

SEP . OCT . NOV . 

GAMMA (Counts per minute/c~bic meter) 0 . 0001 0.0001 0 . 003 

DEC . 

0 . 005 

BE- 7 (Femto-Curie/cubic meter) 28 . 00 29 . 30 65 . 60 65 . 10 

SR- 90 (Fem to-Curie/cubic meter) 0 . 10 

ZR- 95 (Femto-Curie/cubic meter) 0.12A O.lOA 0 . 03A 

CS-137 (Femto-Curie/cubic meter) 0 . 18 0 . 21 0.36 0 . 23 

CE- 144 (Femto-Curie/cubic meter) o. 68 0 .48 0.66 0.71 

Stable PB (micrograms/cubic meter) 3 . 35 

PB-210 (Fernt o -Curie/cubic meter) 4.22 

Note : Errors are less than 20% e xcept A= error between 20% and 100% . 

the upslope and downslope wind regimes when activated by an external signal . 

A particulat e s ampler , being i nstal led by the Energy Research and Deve l opment 

Administration, Health and Safety Laboratory , will provide the wind direction 

signal for our sampler. 

5. 1. 5 Carbon Monoxide Measurements 

Wolfgang Seiler, Principal I nvestigator 

Max Pl anck Institute 

Mainz , Federal Republic of Germany 

EQUIPMENT 

Because of several technical difficulties with the CO-instrument as well 

as difficulties in the transportation of calibrati on gases between Mainz, and 

Mauna Loa Ob servatory, t h e greatest part of the CO registrations obtained at 

MLO in 1 973 and 1974 coul d not be used for analysi s . On the basis of the 

experi ences obtained i n oper ating the CO-analyzer over an extended period at 

MLO , a new CO-anal yzer was constructed in 1974 and i nstalled at Mauna Loa 

Observatory in March 1 975. The new CO-instrument i s based on the same pri n -

cipl es a nd chemi cal methods a l ready described in GMCC Summary Report 1 973 . 

Th e detection limit of the CO-anal yzer i s 0 .1 ppbv. The accuracy i s± 3% 

f or a CO mixing ratio of 0. 1 ppmv. The improved CO-i nstrument works conti n -

uously except for short peri ods every two weeks when the exchange of several 

chemical s, e . g., sil ver oxide , is being done . The zero point of the co- instrume nt and the dri ft stability of the calibration curve are controlled 

automatically once every 90 minutes and once every 3 hours, respectively . 

100 
o HTO 

>---i HTO COMBINEO SAMPLES o HT 

; ~~~ NUCLEAR TEST n1Mt l 200-t---'-~-"="-'-"'-"'=-""'---'-="--'"""-""-'-''--~~~~~~~~~~~~~--.--~~~~~--,.~~~~~~~--1 

FAIRBANKS, ALASKA 9 QQ 

150 

~ 100 <( 

er> 

E 

en ' 50 ::;: 

0 

!;:t 

I 

I100 

50 

0 0 

0 0 00 • 

o Oooooo ooooo oc:ooo o o oo 

MAUNA LOA, HAWAI I 

0 

0 O oO 0 o ~cAf'>,, t:fJ OOQjl 

0 

.. .. 

0 

0 

0 ~ 

. ... 0 

0 

oo 

0 

0 

0 Oc 

. .. 

0 

0 oo 

Oo O Oo 

0 0 

( 

00 o 0 o 0 oo ooo 0 oooo oo oo <:Po o o oooo oo ooOooo oooo o 

00 

0 

0 c 

. . . o+-"~•:.._"~-·-·~·~-~·~-~~_;:._· ~·~ -·~~·--1,,,.L..-~·'--~·'--·-·~·~·-~··'--~·~·L~·~·~H~~·~·~·~·~·~~··~·'--~-~· -'j~ 

100 

50 

BARING HEAD, NZ 

OoOO 000 

0 0 

0 oOQOoo oOcfF0ooooo 0ooo0 0 o 0 0 o o o o o o 00o00 o o o o 0 o 0 o 0 0 0 

0 

0 ~~~~~·~·~·'.__~•-f!,:•!....J·L.J·~•!.._,..-'•~·~··~ .!....·~·~· .. · ........ ,.~.~·~·· ...... I ·~··~·~··...:-•~======l,.-J I ======+-..1::::====s.,.t:======:!,!=====:::::!.,..t:====::::::IJ JAN FEB MAR APR MAY J OCT NOV lJ'I JUL AUG SEP DEC 

1975 

Figure 61 . Atmospheric tritium at Fairbanks, Alaska; Miami, Florida; Mauna 

Loa Ob servatory, Hawaii; a nd Baring Head, New Zealand, 1 975 . 

101 
CALIBRATION 

In 1973 and 1974 the CO-instrument was calibrated by using cylinders of 

compressed air with known CO-mixing ratios comparable with the expected 

ambient air mixing ratios at MLO in the range of 60-200 ppbv. The cylinders 

were filled and analyzed at the Max Planck Institute (Mainz), shipped to 

Mauna Loa Observatory and returned to Mainz after the cylinders had reached 

one-tenth of the original pressure. The recalibration of the cylinders at 

Mainz indicated an unreproduceable change of the CO mixing ratio in the 

cylinders with time , amounting to as much as ± 50%. As a consequence , the 

accuracy of the CO-calibrations at Mauna Loa was questionable and an analysis 

of the CO-registration was not possible. Furthermore , the l oss of some 

cylinders during transport prevented additional checks. 

Because of these difficulties a completely new calibration system was 

developed and installed at Mauna Loa in March 1975. The schematic diagram of 

this system is shown in figure 62. 

In this system a constant flow (3 cm3/min) of a CO calibration gas with 

a CO mixing ratio of 20 ppmv is diluted by a CO-free carrier gas (synthetic 

air passed over molecular sieve and hopcalite). The flowrates of both flow 

streams are measured by electrical flowmeters and registered continuously so 

that the CO mixing ratio of the air flow leaving the calibration device can 

be calculated. The calibration system was checked at Mainz for a period of 

about one year and found to produce a CO-calibration gas with an accuracy 

better than ± 5%. In addition , this syst em wa s checked after the installat i on a t Mauna Loa for stabi lity by a weekly calibration of the CO instrument 

using a manual but completel y different calibration t echnique. Table 26 

gives a comparison of the automatic and the manual calibration for several 

days. The data indicate a sufficientl y high stability of the CO-calibration 

gas in the cylinder. 

After one year of operation t he tank pressure has decreased by only 5% 

of its original value of 150 bars. Thus, the CO-cylinder used in the automatic calibration device may last for a period of several years. 

SYNTHETIC AIR 

CO-CALIBRATION GAS 

20ppmv 

PRESSURE 

REGULATOR 

PRESSURE 

REGULATOR 

MOLECULAR 

SIEVE HOPCALITE 

FLOWMETER t-------~~----tCO-INSTRUMENT 

Figure 62. Calibration system installed at Mauna Loa in March 1975. 

102 
Date : 

Automatic 

calibration (ppmv) 

Manual 

calibrat ion (ppmv ) 

DATA 

Table 26. Comparison of Calibration 

4/16/75 5/7/75 6/11/75 7/16/75 8/6/75 10/15/75 10/24/75 12/3/75 

0.115 0. 112 0.111 0.111 0. 111 0.112 0. 111 0.125 

0.119 0. 112 0.118 0.115 0.114 0.119 0 .111 0. 121 

With the exception of some short interr uptions the CO-instrument worked 

continuousl y f rom March to December 1975, so that for the first time a coregistration i s available for the case of unpoll uted air masses over a l onger 

time period. The r egi strations were evaluated at the Max Planc k I nstitute at 

Mainz. Some results are shown in Fig. 63 to Fig. 65 . Fig . 63 shows a section of the original CO-regi stration obtained on Jul y 7, 1975 , during the 

time period starting at 11 a .m. and end ing at 4 p.m. During this peri od the 

zero point control was established f i ve t i mes and the automatic calibration 

of the instrument was performed three times. The CO-registration does not 

show any short-term fluctuations except a few spikes caused by automobil e 

exhaust. The s table CO-mixing r atios indicat ed by the regi strati ons are 

typical for Mauna Loa , indi cating t hat t his station i s not influenced by 

anthropogenic activities. The three spikes occurri ng at the beginning and at 

the end of the registrations are caused by automobiles arriving and l eaving 

the observatory. 

. Fig. 64 shows the CO-mixing ratio as a f unction of time-of-day averaged 

over a quarter of a year. It seems that carbon monoxide has a slight diurnal 

variation wit h a maximum during t h e afternoon and a minimum during the early 

morning. It is possible that these diurnal vari ations a r e due to the t wo 

distinct wind regimes observed at Mauna Loa with upsl ope winds dur ing daytime 

and downslope winds during the ni ghttime , originating from r egi ons below or 

above the trade wind inversions, respectively. If this inter pr etation i s 

correct it would i ndi cate a vertical CO-gradient in t he l ower a nd middle 

tropos phere with higher CO-mixing r ati os in the lower troposphere bel ow the 

t rade wind inversion. This behavior has been observed previousl y in the 

trade wind zone of the Atlantic Ocean at Teneriffa Isl and . 

The mo st important feature of the CO-measurements at Mauna Loa appears 

to be the seasonal variation of the carbon monoxide mixing ratios shown in 

Fig. 65. There i s a maximum during March/April with values of 0. 12 - 0. 13 

103 
-> E 

8: 

~ 

0 

:p 

~ 

OJ.. . ' 

0.3. c 

' .2 . -

c 

.... : ~ .. : Ci ' u 

' 

~l 

~ 

~ 

I 

+ 

I I 

i 

M~una . Loo . 

July.· ~ '.1915 

· C . . 2 

0 

·~· 

: c; 

u 

. i I ' I 

. : ~+ --@- -< -+ 

. I f : + ! 

' 

Local Standard Time 

Figure 63 . Section of the original CO-registration . 

~ 

.! 

:a 

Q 

: .. -6 

a 

:; 

a 

I 

...... 

i } 

ppmv and a minimum in August/September with values of 0 . 07 - 0 . 08 ppmv. It 

is interesting that t he maximum values are comparable with typical Northern 

Hemispheric CO-mixing ratios observed elsewhere, whereas the minimum values 

are characteristic for air masses of the Southern Hemisphere so that it looks 

as if Mauna Loa is seasonally influenced by the d ifferent hemi spher e air 

masses because of the seasonal movement of the ITC. If this is the case , 

other pollutants like CFCl3 and CF2Cl 2 should show a similar seasonal trend. 

Such a trend, however , does not seem to exist. Another conceivable explanation is the influence of photochemical processes combined with a seasonal 

variation of the north-south transport of air masses in the sub-tropical 

regions of the Northern Hemisphere due to the seasonal change of the Hadl ey 

cell. Photochemical processes would include the oxidation of methane by OHradicals resulting in the formation of carbon monoxide, and the oxidation of 

carbon monoxide by the same radicals. Further data must be obtained to 

substantiate the observed seasonal behavior and to find the correct explanation for the observations. 

104 
0.13 

Maun a Loa Observatory ( 19. 5 ° N) 

0.121--- 1975 

> 0.11 

E 

o_ 

o_ 

April -May -June 

x ~ 0.10 ~=~=!!=----t-------1--------+---------""*""'-------1 

.Q 

I 

0 

u 0.07 

--x--x x-x-x-~x 

6 12 18 21. 

Local Standard Time 

Figure 64 . CO mixing rat io as f unction of time. 

0.13 Mauna Loa Obser vatory (19.5 ° N) 

> 

E 2i 0.11 

.Q 0 0.10 

a: 

~0 09 

19 75 

x 

:L 

I 0.08 1-- ----l ~~ -+ -l-~~--->.,,.---+-~---7'-0<....-~-+-~~~ -t-~--i 

0 

u 

007 

j F M A M j j A s 0 N 

Figure 65. Monthly varia t ion of carbon monoxide mix.i.ng r a tios . 

105 

D 
5.2 Barrow Observatory 

5.2.1 Stratospheric Nitrogen Dioxide (N02) Measurements 

John F. Noxon , Principal Investigator 

Aeronomy Laboratory, NOAA 

A prototype spectrometer to monitor stratospheric N02 using ground-based 

optical methods was installed at Barrow in earl y August 1975 and reinstalled 

in November . The instrument views out a double-pane window onto a mirror and 

into t he zenith sky. By measuring certain absorption features of N02 in the 

twilight sky, the instrument can automatically determine the stratospheric 

N02 abundance. A large amount of good data has been accumulated and is now 

undergoing analysis. It is clear that the instrument functions as expected 

and that a continuous series of daily measurements is now in hand. 

The present instrument is due to be replaced in the summer of 1976 by a 

fully automated version that will be located on the roof of the building with 

the recording system located inside. The new instrument will track the Sun 

and measure the direct transmission in the N02 absorption bands and automatically determine the tropospheric and stratospheric N02 concentration. 

Similar instruments will be developed for use at the three other GMCC 

observatories. Eventually, N02 instruments will be installed at all the GMCC 

observatories. 

5.2.2 Smithsonian Solar Radi ati on Program 

Bernard Goldberg, Principal Investigator 

Smithsonian Radiation Biology Laboratory 

The Smithsonian Radiation Biology Laboratory has solar radiation monitoring equipment in Barrow, Al aska , continuously recording the spectral 

distribution of natural daylight. There are two types of detectors in use at 

this location: Eppley precision pyranometers and a photoelectric detector 

which is used for monitoring the UVB spectrum. The six pyranometers use 

Schott colored domes to produce 100-nm to 2800-nm spectral data . The photoelectric detector is used with eight pairs of interference filters to monitor 

the UVB in 5-nm bands from 285-nm to 320-nm. 

The information from these detectors has been gathered by a digital 

acquisition system on punched paper tape. Because the old acquisition system 

failed in September 1975 after approximately four years of continuous use, 

the Radiation Biology Laboratory modified a commercial system to replace it. 

The new modified system will be put into operation in March 1976. The values 

of the daily totals of the spectral data collected from the pyranometers have 

been published by the Smithsonian Institution, and are availabl e for the 

years 1971-1973. The data since 1973 are being prepared for publication. An 

analysis of the data will be published in Solar Energy sometime in 1976. 

106 
5.3 South Pole Observatory 

5.3.1 Atmospheric Electric Measurements 

William Cobb , Principal Investi gator 

Atmospheric Physi cs and Chemistry Laboratory, NOAA 

A 5-year program of atmospheri c e l ectric measurements i s now in its 

fourth year at the Amundsen-Scott South Pole Station. After the opening o f 

the new station in January , electri cal sensors were moved from the o ld VLF 

site to the new Clean Air Facility where the a ir-Eart h conduction c u rren t 

density and the atmospheric potential gra dient are continuously recorded. 

The potential gradient sensor, an i nduction-type field mill desi gned to 

withstand low temperatures, is mounted on a post about 1 m above the s now 

surface. The air-Earth current sensor consists of a passive antenna about 12 

m long, suspended 1 m above the snow. Control panel s and a strip chart 

recorder are located in the " c l ean-ai r" building. To s uppl ement the s urface 

measurements, modified radiosondes, designed to measure the air-Earth curren t 

density to as high as 35 km, were released biweekly throughout the year by 

the National Weather Servi ce. Major objectives of the program are to establish an environmental benchmark of electrical parameters sensitive to aerosol 

pollution , and also to investigate those processes that may control o r influence the "global circuit ". The global c ircuit is a term used to describe the 

flow of electri cal current between the Earth and the ionosphere , which, 

according to the most widely accepted hypothesi s , i s main tained by the everpresenL g l obal thunderstorm acti vity. Confirmation of thi s hypothesis has 

b een difficult because at mo st measuring sites the global effects are ma s k ed 

b y l ocal influences resulting from man-made pollution , radioactive soil s , 24 -

hour diurnal cycles, etc. , effects t hat are absent on the pol ar p l a teau. 

The s urface measurements of the potential gradi ent and the a i r-Earth 

c urrent density at the South Pole a r e provi ding the best evidence yet obtained in support of the global thunderstorm hypothesis. Thus in Fig. 66 , whic h 

shows the mean d i urnal variation of the potenti al gradi ent at the Pole , the 

peak at 1500-1900Z occurs when the sun is passing over Africa and South America where thunderstorm activity is the greatest. A secondary peak at 0700Z 

occurs when the sun passes over Asia, and the minimum potential gradient 

occurs when the sun is over the Paci fic Ocean and global t hunderstorm activity i s at its lowest level . We are , i n effect then , monito ring c hanges in 

the global thunderstorm acti vity from the South Pol e. 

With respect to aerosol pollution , the measuremeQts must be considered 

over l ong time spans where the baselines establ ished now may be checked at 5 

to 10 year intervals in the future to look for possible secular chan ges. It 

i s especially important to establish an index for stratospheric conditions 

wh ere particle residence times are much longer than in the troposphere. Frequent radiosonde ball oon f l ights are being made of the air-Earth c urrent density to establ ish such an index for t h e stratosphere. The presence of only 

5 to 10 aerosol particles per m3 will significantly reduce the a i r-Earth 

current measurement in the stratosphere . Cl assical theory claims that the 

a ir-Earth current in fair weather is constant with a l titude. However, balloon measurements at the Pole (Fig. 67 ) have shown that this is frequently 

107 
N 70 E 

.>< 

• 0 

120 - _ i <( E w > er 

<( 

i-: 60 ::E z er w 0 0 I- <( 

er 80 ~ (.!) w 

0 .J z <( ::::> 

~ 50 :I: 

I- w .J I- <( 0 

CL 4 0 CD g 

(.!) 

00 06 12 18 24 

GMT 

Figure 66. Mean diurnal variation of the potential gradient (solid line) at 

the South Pole and the global thunderstorm area (Whipple and Scrase, 1936). 

30 

20 

IS 

10 

AIR-EARTH CURRENT DENSITY 

SC'UTH POLE 

MEAN OF IY SOUND INGS 

0 I 

CURRENT 

2 3 y 

R/M 2 X I~ 12 

Fi gure 67. Average air-earth conduction current density from balloon measurements at the South Pole . 

108 
not true and that the c urrent is more l ikel y to peak at about 11 km and decrease slowl y thereafter. The balloon flights analyzed to date suggest that 

factors in additi on to the global thunderstorm activity influence the stratospheric air-Earth current at the Pole. One possibility is the presence of 

enhanced particulate concentrations extending we ll into the upper stratosphere . 

The South Pole atmospheric e l ectric program has been supported by the 

National Science Foundation (Grant OPP74-19486) , the National Weather Servi ce , and the Atmospheric Physics and Chemistry Laboratory of NOAA , as well 

as by the GMCC program. 

5.4 Samoa Observatory 

5.4.1 Trace Elements in the Marine Atmosphere 

Robert A. Duce , Principal Investigator 

Graduate School of Oceanography 

University of Rhode Island 

There has been increasing concern in the last few years over the evidence that measurable quantities of l ead and perhaps ot her trace metals, DDT, 

PCB, petroleum hydrocarbons and other organic substances are transported to 

the open ocean by the atmosphere , either as particles or in the gas phase 

(Study of Critical Environmenta l Pr obl ems, 1970; FAO Fisheries Reports, 1971). 

Al though this long-range transport of atmospheric pollutants is generally 

accepted , there have been few concerted efforts to r elate atmospherically 

transported pollutants , particul arl y trace meta l s and chlorinated hydrocarbons , to the general problem of open ocean pollution until the initiation of 

our NSF-supported program in 1972. Before thi s program began there was virtually no information on the mean concentration of these substances in the 

atmosphere in the westerlies over the North Atl antic , where pollutant transport from the heavily industrialized North American continent would be a 

maximum. Pr evious work in this area had been limited to a small number of 

samples collected from ships without systernat~c cont rol of geographic l ocation and without consideration of rapi dly changi ng meteorol ogical conditions. 

The flux of most of these atmospheri c pollutants to the ocean was completely 

unknown as was the rate of the ir re-introduction into the atmosphere by spray 

and bubble breaking. Very little i s still known concerning the mechanisms of 

deposition of these pollutants i nto t he ocean from the atmosphere . 

The most practical way to obtain reasonable values for atmospheric concentrations and fluxes of pollutants out over the ocean i s t o have a stat i onar y sampling site in operation over a relati vel y extended period of time. 

In this way meaningful information on the "c l imatological mean" concentration 

of the substance of interest can be obtained . For thi s r eason we have chosen 

stati onary tower sit es in mid-ocean l ocations for our studies of the chemistry of the marine atmosphere. 

109 
Our initial tower site was on the windward coast of Oahu , Hawaii, and 

was utilized from 1968 to 1970 and in 1975. This mid-Pacific site is in the 

northeast trades and is an ideal location for evaluating l ong-range transport 

of substances from North America to the tropical North Pacific. Our second 

tower site was on Bermuda and was utilized from 1972 to 75. This site is 

approximately 1100 km off the east coast of the United States, primarily in 

the westerlies, but often under the influence of the North Atlantic trade 

wind regime in the summer, with near surface air flow from the eastern 

Atlantic. The primary value of this site was thus its l ocation in an area 

where there were clear shifts from synoptic patterns with a reasonably close 

major air pollution source to synoptic patterns with wind trajectories passing only over the open sea for thousands of kilometers. 

Over 90% of the atmospheric pollutants. are injected into the Northern 

Hemisphere . With the relatively short residence times of atmospheric particles (days to 1-2 weeks) and the relatively long tropospheric mixing times 

between the Northern and the Southern Hemisphere, significant differences 

should be observed for anthropogenic source substances present on atmospheric 

particles at remote areas in the two hemispheres. To date, there is no 

information on trace metal distributions in remote marine Southern Hemisphere 

locations. For this reason we constructed a walk-up sampling tower in 

October 1975 at Cape Matatula adjacent to the new NOAA GMCC Observatory (Fig. 

68). 

. ~ 

. 

110 

Figure 68 . University of Rhode 

Island sampling tower at Cape 

Matatula , American Samoa. 
The base of the Samoa tower is located about 30 m above sea l evel, near 

the edge of a rather precipitous cliff on the southeast side of Cape Matatula. 

It is thus ideally located, relative to the prevailing southeasterly trades, 

to avoid local contamination, both from man-made sour ces and from natural 

erosion products and surf spray. The tower itself is 20 m high, with the 

tower top approximately 50 m above sea level. Smoke flare tests indicate 

that surface air blowing up the face of the cliff does not reach more than 

halfway up the tower before passing by the tower. Samples collected on the 

top of the tower thus receive no local contamination gener ated by air blowing 

up the cliff. 

In any atmospheric collection program of thi s type it i s criti cal that 

as much as possible be known about the past history of the air being sampled. 

The pumps used to collect the samples on the tower are controlled by wind 

direction through a directional air sampl er control. Thi s directional control allows the pumps to be operated automatically when the wind is blowing 

from some predetermined sector of the compass, thus avoiding the local contamination that can occur when the wind is off the land . Many filter holders 

have a door that automatically closes over the filter when the pump is shut 

down because of out-of-sector winds. Thi s prevents filter contamination from 

non-marine air when the pumps are not operating. 

An Environment/One Model Rich 100 recording condensation nucleus counter 

(Environment/One Corp., Schenectady, New York) is also located near the top 

of the tower. Since local pollution parti cles are excel lent condensation 

nuclei (CN), s hort term rapid variations in CN counts can indi cate air mass 

changes and/or possible local contamination of samples. The CN counte r is 

integrated into the directional air sampling contr ol system so that collec -

tion occurs only when the wind i s off the ocean and when CN counts are near 

background for marine air, 300-400 per cm3 . This is an added safeguard 

against collection of local pollution. Recorders for wind speed and direction, CN counts, rainfall, and pump operati ng times are housed in the small 

air-conditioned building near the base of the tower. 

Atmospheric collection equipment (i.e. fil ter hol ders, impactors, e tc.) 

is located on the top level of the tower. Bulk par ticulate samples f or trace 

metal analysis are collected on double Whatman 41 f ilters (20 x 25 cm) or 

Nuclepore filters mounted in all plasti c filter holders and rain shelter s . 

Particle size separated sampl es are collected using a Sierra Hi- Volume cascade impactor. The particles for trace metal anal ysis are deposited on 

Whatman-41 fil ter paper on each impactor stage. The f ifth stage is foll owed 

by a final filtration through Whatman-41 filters. Particles to be analyzed 

by electron microscope and microprobe are collected on 47-mm 0.4- μm Nuclepore 

filters. Bulk particles to be analyzed for total organi c carbon are collected on pre-combusted Gelman Type-A gl ass fiber f ilters. High-volume 

impactor samples for organic carbon analysis a l so utilize glass fiber filters. Air sampling pumps are separated from the f ilters and impactors by 8 

meters of 7.6-cm diameter fiber glass tubing, the pumps being located at a 

lower level of the tower. This avoids contamination from the pumps themselves (Hoffman and Duce, 1971). 

111 
Samples for the vapor as well as the particulate phase will be collected 

for Hg and As. The Hg collection system and analysis technique to be employed is a modification of the design now used by the regional EPA laboratory in 

Needham, Massachusetts, to monitor Hg in the atmosphere (Spittler et a l., 

1976). We will use a gold amalgamation trapping stage. Braman and Johnson 

(1 974) found that gold effectively amalgamates and traps all the major atmospheric species of Hg: e lemental Hg, inorganic Hg (II) compounds, methyl Hg 

(II) type compounds, and dimethyl Hg. A column packed with gilded glass 

beads will provide an efficient collector at much less expense than a corresponding volume of gold beads. 

Techniques have been developed for the separation and collection of 

gaseous and particulate As in the atmosphere. After removal of the particle s 

by a Nu clepore filter, the gas phase i s coll ected on a series of Whatman-41 

filters impregnated with an aqueous solution of 10% glycerol and 10% polyethylenimine, a strong o r ganic base. This system has been tested in the 

laboratory and in the field and is quite efficient for such species as As405 , 

the most volatile As compound that is stable in a i r , and hydroxydimethylarseni c acid. 

Samples will be collected for PCB and DDT by using the technique of 

Bidleman and Olney (1974), which involves the passage of large volumes of air 

first through a precleaned glass fiber filter and then through a s eries of 

porous polyurethane plugs for vapor phase collection. 

An initial test phase 

in January-February 1976. 

planned in Samoa from June 

of the entire sampling system will run for 6 weeks 

Two 6-month inte n s i ve sampling periods are now 

to November 1976 and May to Octobe r 1977. 

112 
6. DATA MANAGEMENT 

This section documents changes in the various systems and t echniques 

used to acquire and reduce GMCC baseline data. Information on data archiving 

is also presented. 

6.1 Data Acquisition 

6.1 . 1 Standardization of Hardware 

The maj or task during 1975 wa s to standardize the computer ha r dwar e at 

each station in order to avoid the complexity imposed by operating individualized hardware . The largest number of modifications required was at South 

Pole. There a new display c l ock and its accompanying interface were installed. Also a drawer that allows direct signal access t hrough the use of terminal strips r eplaced a matrix board configurati on. In addition , the core 

size was increased to 16k words, so that the software at Mauna Loa and 

Boulder could be used at the other stati ons as well. These c h anges were 

impl emented in December, bringing the ICDAS at the South Pole into complete 

conformity with the other stations. 

6 .1. 2 So ftware Modifications 

To facilitate the reduc tion and subsequent processing of t h e data t apes 

from the stations, the conte nt a nd dimension of the data a rrays was standardized with the use of the new executi ve progr am call ed Basic Operating System 

Software (BOSS) 75170. BOSS was installed at the Mauna Loa Observatory during the sununer, at Barrow in October, and at the South Pole in December. Any 

future modificati ons to this software will not c hange the operating p r ocedures, content, or s tructure of the data arrays to any significant degree. 

6 . 1.3 Installations 

BARROW 

Sh ortl y after the first of t he year, the hardwa r e components of ICDAS 

data system for the Barrow station we re assembled , tested and evaluated (F i g . 

69). The system wa s installed at the station during the first two weeks in 

April with onl y minor probl ems. Data acqui s i tion commenced April 15. The 

flow of data from Ba rro w s uffered only minor i nterruptions until a major 

power outage occurred in mid-November. During this period of low voltage , 

s ome components were damaged. The data system r emaine d inoperative until 

after the f i rst of the year , because of the complexity of the damage . 

113 
Figure 69. The ICDAS installation at 

the GMCC station, Barrow, Alaska . 

BOULDER 

By mid-year, the main components of the data r eduction facility at 

Boulder had been assembled and tested . The facility consists of a magneti c 

tape drive, minicompute r , and teletype like those installed at each station, 

and a dual disc system, a graphics display , and a high-speed reader and punch 

(Fig. 70) . This facil ity will be used to read and check the data tapes from 

t h e observatories. If parity errors are present, a new clean tape will be 

prepared for further anal ysis at the ERL computer facility . 

SAMOA 

With the completi on of the data reduction facility , work began on testing the components of the ICDAS for the observatory at American Samoa. All 

t h e latest modifications were included and the system was operating in 

Boul der by mid-September. Tests continued until mid-November when the equi p -

ment was prepared for shipment to Samoa. The data system was installed witho u t difficulty in January 1976. Th e installation in Samoa differs from those 

at the other GMCC observatories in that the digital components run on power 

Figure 70. 

facility 

Boulder, 

The data reduction 

in operation at 

Colorado . 

114 
from an uninterruptable power suppl y (UPS ) . Through the use of this device, 

it is possible to keep the computer and tape drive on line while the power 

shifts from i sland power to emergency generator power and back agai n. If 

this method of bridging short (<5 min) power outages proves successful, uninterruptable power supplies may be installed in Barrow and at the South Pol e 

next year. 

6.2 Data Reduction 

In October, a new group was formed within GMCC to manage the flow of 

data from the observatories to the national archive, the World Data Center in 

Asheville, N. C. The group ' s main functions are named in its title , the Acquisition and Data Management Group , or A&DM. In the latter half of the year, 

emphasis was p l aced on developing programs to read and display data for quality evaluation. This resulted in a three-step evaluation routine. In the 

first step only the quality, identification , and continuity of the magnetic 

tape itself are checked. In the second step, the performance of the BOSS in 

terms of calibration and missing data i s checked. And in the last step t he 

measurements are displayed in tabular or graphic form for evaluation by the 

responsibl e scient ists. This sequence of evaluation will probably undergo 

consider able change as new problems are uncovered. 

6.3 Data Archiving 

6.3.1 Total Ozone 

During 1975, total ozone data for the period January 1974 through June 

1975 were sent to the Atmospheric Environment Service of Canada (Downsville, 

Ontario ). This agency publishes ozone data for the World Meteorol ogical 

Organization (WMO). The observations were from Bismarck , N. Dak.; Caribou, 

Maine; Green Bay, Wis.; Tallahassee , Fla. ; Mauna Loa Observatory , Hawaii ; 

Wallops Island, Va.; Na s hville , Tenn.; Boulder, Colo.; White Sands, N. Mex.; 

Huancayo , Peru. Data from the winter months of January and February are 

missing for Barrow, Al aska. 

6.3.2 Surface Ozone 

Measurements of the concentrati on of ozone at the surface are also published by the Atmospheric Environmental Service of Canada. During 1975 , data 

from the Barrow Observatory, for the period Marc h 1973 to July 1975 , and from 

t he Mauna Loa Observatory for August 1973 to July 1975 were archived (see 

Section 4.1.3). In both cases a device employing an electrochemical concentration cell was used to measure ozone . The da ta for the period March 1974 

to November 1974 from the South Pole station were a l so archived . Measurements at the South Pole were made with an instrument using a chemiluminescent 

determination of ozone . The data are one -hourly average concentrations . 

115 
6.3.3 Solar Radiation 

Daily integral values of the horizontal incident radiation measured at 

the Mauna Loa Observatory were sent to the World Data Center A in Asheville, 

N.C. , for the period January through August 1975. 

116 
7. RESEARCH CONTRACTS 

This section provides a brief review of each research contract or grant 

funded by GMCC during 1975. 

7.1 Center for the Environment and Man 

Title: A Study of Transmission of Solar Radiation by the Atmosphere 

Princ i pal Investigator: G. D. Robinson 

Period of Study: June 1 , 1975 to January 31 , 1976 

NOAA Contract No: 03-5-022-79 

The work proposed falls into three categories: 

1. The Re l evance of Solar Radiation Measurements in Monitoring for 

Climatic Change. 

The final r esult will be a critical essay s urveying the purpose , potential, and achievement to date of the measurements now being made at Mau na Loa 

Observatory. It will be produced in close consultation with the staff of Air 

Resources Laboratory, and its intention will be to help them to decide what 

(if any) changes should now be made in t he instrumentation, the mode of its 

use , and the reduction and retention of data. 

Attenuation by absorption and scattering by gases and particles will be 

considered , with regard to both the idealized performance of the current 

equipment and its actual performance in the field. The work wi ll include an 

analysis of the ideali zed and likely responses of the equi pment to hypotheti -

cal perturbations; the analysis will use s imp l e s ingle-scatter approximati ons 

(whic h can be s hown to be s ufficiently accurate for the purpose). The fol -

lowi ng matters will also be considered : 

0 The nature of the requirement for continuity~ontinuous vs. 

expedition-type operation at remote station s . 

° Filter vs. spectrometer for the required spectral separation. 

0 The case for less remote stati ons with higher than network standards 

of accuracy. 

2. A Continuati on of the Examination of the Mauna Loa Results, Wi th 

Particular Reference to Instrument Performance. 

In CEM Report No. 4 1 49-507 (NOAA Contract No. 03-3-022-157) an analysis 

was made of certain data averaged over 10 days in 1974 This showed that 

certain components of the Mauna Loa equipment were performing at the expected , geophysically useful, leve l of accuracy. It i s proposed to continue 

this analysis to s how the day-to-day variance , and to examine the performance 

117 
of some other components that do not on first examination appear t o reach the 

required standard. 

In addition, one year' s tabulations of the Mauna Loa radiation record , 

arranged according to solar angle, will be examined. Occasions when the 

record is sufficiently complete and without obvious error will be isolated, 

and a selection will be examined by the methods' used in the work performed 

under Contract No. 03-3-22-157. 

Any repeated anomalies of glass filter performance (i.e., apparent systematic deviation from accepted spectral properties) will be isolated. Alternative explanations of the anomalies , related to atmospheric attenuation or 

the assumed extra-terrestrial spectrum, will be examined. 

3. Consultation 

The services of Dr . G. D Robinson will be available for consultation 

with staff members of ARL at their request, within the proposed effort. 

7.2 Geophysical Institute, University of Alaska 

Title: An Investigation of Aerosol Charac teristics at Mauna Loa 

Observatory 

Principal Investigator: Glenn E. Shaw 

Period of Study: October 1, 1974 to February 1, 1975 

NOAA Contract No: 05-5-222-310 

The work proposed will accumulate additional information on the radiation field at Mauna Loa by measuring the following parameters during c l ear 

weather periods: 

a) Atmospheric transmission (optical depth) at six narrow wavelength 

intervals distributed over the visible spectrum. 

b) The distribution and magnitude of diffuse sky intensity (in absolute units) over the entire celestial hemisphere in six narrow 

wavelength regions . 

The above parameters will be derived from measurements made with special 

interference-filter photometers that have been developed over the past several years. The diffuse radiation field at small angular distances from the 

sun will be evaluated with a photoele ctric coronometer. 

Interpretation and analysis will proceed as follows: 

WAVELENGTH DEPENDENCE OF AEROSOL OPTICAL DEPTH 

The optical depths at each filter wavelength due to scattering and 

absorption by atmospheric aerosols will be obtained from sun photometry 

118 
measurements. A smooth curve drawn through the data points will estimate the 

shape of aerosol optical depth curve with wavelength. 

INTERCOMPARISON WITH EPPLEY NORMAL INCIDENCE PYRHELIOMETER 

Based on the inferred aerosol extinction curve (as derived in "a.") and 

using published values of the solar flux , the incoming direct sol ar radiation, wavelength by wavelength, will be cal culated over t he visible spectrum. 

The r esults will be combined with published curves for the Schott Standard 

glass filters and then compared with the stations normal-incidence pyrheliometer data. Water vapor absorption effects will be minimized by subtracting 

r eadings taken through two d i fferent cutoff filters to derive the incoming 

solar flux between wavelength regions in the visible region. In addition, 

aerosol optical depths derived with our photometer, and with the new multiwavelength normal incidence pyrheliometer at Mauna Loa , will be compared to 

establish representative errors that may arise when two entirely different 

instruments are used to derive atmospheric transmi ssion . 

EVALUA TION OF AEROSOL SCATTERING PHASE FUNCTION 

The form of the aerosol scattering phase function will be estimated by 

employing an analysis of the distribution of s ky intensity in the solar 

almucantar. 

EVALUATION OF MULTI-WAVELENGTH DIFFUSE FLUX 

The observed sky intensi ty will be numerically integrated over solid 

hemispheric a ngle to obtain numerical estima t es of the downwelling diffuse 

fluxes a t the filter wavelengths ; these will be compared with calcul ated 

values t hat would result from a pure Rayl eigh-scattering a tmosphere. 

CALCULATIONS OF BACKSCATTERED ENERGY AND ABSORPTION 

The method described by Robinson (1974) will be utilized to evaluate 

the ratio of backscattered-to-absorbed energy f luxes by the Earth-atmosphere 

system at the filter wavelengths. 

7.3 Institute for Arctic and Alpine Research (INSTAAR) 

Title: Background Gas Sampling at Niwot Ridge , Colorado 

Principal Investigator: John Cl ark 

Period of Study: December 15, 1975 to December 14, 1976. 

NOAA Contract No: 01-6-022-12770 

The proposed work will continue carbon dioxide flask sampling at Saddle 

Point , We st Knoll on Niwot Ridge 23 miles west of Boulder, Colorado. These 

measurements wer e previ ousl y made during the years 1966 through the beginning 

of 1974. In addition to paired carbon dioxide flask sampling, one pair of 

f l asks will be exposed for fluorocarbon measurements. Sampling will be made 

on a weekl y basis. However, actual sampling frequency may vary to take 

119 
a dvantage of optimum sampling conditions or becau se of delays caused by 

severe weather. In most cases, sampling will be made at least once every 10 

days over a 1-year period. 

Supplementary meteorological measurements will be made including wind 

speed and directi on , cloud cover, visibili ty , present precipitation, and 

temper a t ure . 

Exposed flasks will be returned to GMCC Boulder for ana l ysis and data 

r e d u c t i on . 

7 . 4 Cornel l Universit y 

Ti t l e: Ca l ibration of Collecti on Procedures for Determination of 

Precipitation Chemistry 

Principal Investigator: Gene E. Likens 

Period of Study: July 16, 1975 to July 15 , 1976 

NOAA Contract No. 04-5-022-24 

GMCC provided partial funding to continue Cornell ' s intercomparison 

study of precipitation collectors and precipitation analysis techniques as 

initi ated under the 1974 ERL Grant No. 04-4-022-31. 

A surrunary of the work performed unde r this contract is contained in 

Section 4. 6 . l. 

120 
8. RESEARCH PUBLICATIONS 

Fegley, R. W. and H. T. Ellis (1975): 

dust cloud layer in the tropics. 

141. 

Lidar observations of a stratospheric 

Geophysical Research Letters, 2 , 139-

Fegley , R. W. and H. T. Elli s (1975) : Optical effects of the 1974 stratospheric dust c l oud. Applied Optics, 14, 1751-1752 . 

Hogan, A. W. and D. Nelson (1975): Aerosol observations over the ice caps . 

Antarctic J. , 1 0, 310-312 . 

Hoyt , D. V. (1 975): New calculations of the Linke turbidity coefficient. 

Q. J. Roy. Meteorol. Soc ., 101 , 383-385. 

Machta, L. , G. Cotton, W. Hass, and W. D. Komhyr (1975): CIAP measurements 

of erythemal solar ultraviolet radiation. Final Report prepared for the 

Climatic Impact Assessment Program, Department of Transportation , Washington, D. C. 

Miller, A. J., J.M. Miller and R. M. Rotty (1975): Two case studies correl a ting the baseline C02 record at Mauna Loa with meteorological and 

oceanic parameters. NOAA Tech. Memo ARL-44. 

Miller, J. M. (1975) : The collection and c hemical anal ysis of preci pitation 

in North America. Proceedings of Water Reu se Conference of American 

Institute of Chemical Engineers, Chicago, Ill., 1975, AICHE. 

Miller, J. M. (1975): A statistical evaluation of the United States preci pitation chemistry network. Precipitation Scavenging (1974). U.S. Energy 

Research and Development Administration. Conf. 740513. 

Turner, T. a nd G. Cotton (1 975 ): Summaries of Aitken concentrations and 

associated surface wind data at Barrow, Alaska, from September 1971 to 

February 1975. NOAA Technical Report ERL 349-ARL2. Superintendent of 

Documents, U.S . Govt. Printing Offi ce , .Washington, D. C. 27 p. 

121 
9. REFERENCES 

Atmospheric turbidity and precipitation chemistry data for the world (Annual): 

Environmental Data Service , Ashevill e , N.C. 

Bidleman, T. F ., and c. E. Olney (1974) : Chlorinated hydr ocarbons in the 

Sargasso Sea atmosphere and surface water. Science , 183 , 516-518. 

Braman, R. S. , and D. L. Johnson (1974): Selective absorption tubes and 

emission techniques for determi nation of ambient forms of mercury in 

air. Environ . Sci. & Technol ., 8 , 996-1003. 

Cadle, R. D. , C. S. Kiang, and J. F. Lewis (1975): A model of the global 

scale disper sion of the eruption clouds from major volcanic eruptions. 

submitted to J . Geophys. Res. 

Eden, R. (1975): Heterojunction I II-V all oy phot odetectors for high sensitivity 1.06- μm opti cal receivers. Proc . IEEE, 63 , 32. 

Ellis, H. T., and R. F. Pueschel (1971): Solar radiation: absence of air 

pollution trends at Mauna Loa . Sci ence , 172 , 845 . 

Elterman , L. (1968 ) : UV , visibl e , and IR attenuation for a ltitudes to 50 km, 

1968. AFCRL Environmental Res. Paper No. 285 , 49 pp . 

Elterrnan , L. (1975): Stratospheric aerosol parameters for the Fuego volcanic 

incursion. Applied Optics, 14 , 1262-1263 . 

FAO Fisheries Reports, (1971): No. 99, Supplement, Report of the seminar on 

methods of detection , measurement, and monitoring of pollutant s in the 

marine e nvironment. Food and Agr i cultural Organi zati on of t he Uni ted 

Nations , Rome , 123 pp. 

Fegley, R. W., and H. T. Ellis (1975): Optical effects of the 1974 stratospheric dust cloud. Applied Optics, 14 , 1751-1752. 

Feussner, K., and P. Dubois (1930): Trubungsfaktor, precipi tabl e water, 

Staub. Te il I. (Turbidity factor , precipitable water, dust. Part I ) . 

Gerlands Beitr. z. Geophys., 27 , 132-175 . 

Galloway, J. N., and G. E. Likens (1976): Calibrat ion of collecti on procedures for the determination of precipitation chemistry. Proc. 1st 

I nternational Symposium on Acid Precipitation and the Forest Ecosystem . 

U.S. Dept. of Agriculture (in press). 

Go ldberg, B. , and W. H. Klein (1974) : Radiometer to monitor l ow l evels of 

ultraviol et irradiance . Applied Optics, 13 , 493-496. 

Go ldberg, B. , and W. H. Klein (1976) : Variations in the spectral distributions of dayl ight at various geographical locations on the earth' s 

surface . Solar Energy (in press). 

122 
Hardy, E. P. , Editor (1975): Sr- 90 and Sr-89 in monthly deposition at world 

land sites. U.S. ERDA Report HASL- 297, Appendix p . A- 1. 

Hoffman, G. L., and R. A. Duce (1971): Copper contamination of atmospheric 

particulate samples collected with Gelman hurricane air samplers. 

Environ. Sci. & Technol., 5, 1134-1136. 

Hogan, A.W. (1975): Antarctic aerosols. J. Appl. Meteorol., 14 , 550-559. 

Hogan, A. W. and D. Nelson (1975) : Aerosol observations over the ice caps. 

Antarctic J ., 10 , 310-312. 

Hoyt, D. V. (1976): The radiation and energy budgets of the Earth using both 

ground-based and satellite-derived values of total cloud cover. NOAA 

Tech. Rept. ERL 362-ARL 4. 

Kasten, F. (1964): A new table and approximation formula for the rel ative 

optical air mass. Tech. Rept. 136, Cold Regions Research and Engineering Laboratory, Hanover, N. H. (AD610554). 

Klein, W. H., and B. Goldberg (1974) : Solar radiation measurements/1968-

1973. Smithsonian Radiation Biology Laboratory, Rockville, Maryland . 

Klein, W. H., B. Goldberg, and W. Shropshire (1976): Instrumentation for 

the measureme nt of the variati on, quantity and quality of sun and sky 

radiation. Solar Energy (in press). 

Kronebach, G. W. (1975): Report of the expert meeting on wet and dry deposition (WADEM) Toronto , Canada, 17-21 November 1975. Unpublished 

report. 

Linke, F. (1922): Transmission koeffizient and trubungsfaktor . Beitr. z. 

Phys. Freien Atmos., 10 , 91 . 

Lockhart , L.B., Jr. , R. L. Patterson, Jr. , A. w. Sanders, Jr. , and R. w. 

Black (1964): Summary Report, Fission product radioactivity in the air 

along the 80th meridian (west) , 195 -19~2 . NRL Report 6104. 

Lockhart, L.B., Jr., R. L. Patterson, Jr. , and A. W. Sanders, Jr. (1965) : 

Atmospheric radioactivity in Antarctica, 1956-1963 . NRL Report 6341 . 

Machta, L., G. Cotton, W. Hass and W. D. Komhyr (1975): CIAP measurement s of 

erythemal solar ultraviolet radiation. Final Report prepared for the 

Climatic Impact Assessme nt Program, Dept. of Transportation, Washington, 

D.C . 

Mason, A. S ., and H. G. Ostlund (1974): Atmospheric HT and HTO: Major HT 

injecti ons into the atmosphere 1973 . Geophys. Res. Lett., 1(6) , 247-

248. 

1 23 
Noxon, J. (1 975): Nitrogen dioxide in the stratosphere and troposphere 

measured by ground-based absorption spectroscopy. Science, 189, 547-

549. 

Ostlund, H. G., and A. S . Mason, (1974): Atmospheric HT and HTO: I . Experimental procedures and tropospheric data 1968-72. Proceedings of the 

International Symposium on Atmospheric Trace Gases, Mainz , West Germany , 

Tellus, 26(1-2) , 91-102 . 

Robinson, G.D. (1974): Scattering and absorption properties of atmospheric 

particles deduced from routine records of solar radiation. CEM Report 

No. 4149-507, The Center for the Environment and Man , Inc. ·, Hartford , 

Conn. 

Robinson , G. D. (1976) : Examination of some solar radiation records from 

Mau na Loa Observatory. CEM Report No. 4181-543, The Center for the 

Environment and Man, Inc., Hartford , Con n. 

Rosen , J . M., D. J . Hoffman, and J. Laby (1975): In situ measurements of the 

recent increase in stratospheric aerosol, presented at the 1975 Spring 

Annual Meeting of the AGU , Wash., D.C. , June 16-19 , 1975. J1.bstract in 

EOS, 56, 365. 

Rudder , R.R., and D. R. Bach (1968 ): Rayleigh scattering of ruby-laser 

light by natural gases. J. Opt. Soc . Am., 58, 1260. 

Study of Critical Environmental Problems (1970): Man ' s impact on the global 

environment. MIT Press, Cambridge , Mass . 319 pp. 

Spittler, J. M., R. J. Thompson , and D. R. Scott (1976): A system for 

c~llection and measurement of elemental and total mercury in ambient 

air. Environ . Sci. & Technol. (i n press) . 

Volchok , H. L. (1975) : Worldwide deposition of Sr-90 through 1974 . U.S . ERDA 

Report HASL-297, p. I-1. 

Volchok, H. L., L. Toonkel, and M. Shanberg (1975): Radionuclides and lead 

in surface air. U. S . ERDA Report HASL-298, Appendix , p . B-1 . 

124 
10 . GEOPHYSICAL MONITORING STAFF 

10.1 Director's Office 

10.1. 1 Director of GMCC 

Donald H. Pack, 1971-July, 1975 

Kirby J. Hanson , 1975-Present 

10.1.2 Director' s Office 

*Kirby J. Hanson, Director 

*Gerald F. Cotton, Stati sti cian 

Colleen H. McAvoy, Secretary 

*John M. Miller , Research Meteorologist 

*James A. Watkins, Executive Assistant 

10.2 Techniques and Standards Group 

*Walter D. Komhyr, Chief 

*Robert Grass, Physicist 

Rudolph H. Haas, Mathematician 

*Thomas B. Harris, Meteorological Techni cian 

*Douglas V. Hoyt, Physicist 

Constance Mapes, Secretary 

*Sam Oltrnans , Physicist 

*Thayne Thompson, Physicist 

10.3 Acquisiti on and Da ta Management Group 

*Gary A. Herbert, Chief 

Arija Bottomley, Clerk 

Joyce Harris, Computer Programmer 

Mi lton s. Johnson, Electronic Technician 

10.4 Analysis and Interpretation Group 

Charles P. Turner, Research Meteorologi st 

125 
10 .5 Mauna Loa 

10.5. 1 Directors of Mauna Loa Observatory 

Jack c. Pales, 1958-1963 

Howard Ellis, 1963-1966 

Lothar H. Ruhnke, 1966-1968 

Howard Ellis , 1968-1970 

Rudolf F. Pueschel , 1970-1972 

Ronald Fegley, 1972-Present 

10 .5 . 2 Mauna Loa Observatory Staff 

*Ronald Fegley, Director 

*Barry A. Bodhaine, Research Physicist 

John F. S. Chin , Physicist 

Howard Ellis, Physi c i st 

*Bernard Mendonca, Research Meteorologist 

Judith B. Periera, Secretary 

Mamoru Shibata , Electronic Technician 

Alan M. Yoshinaga, Analytical Chemist 

10.6 Barrow 

Larry Westerman, Station Chief 

*Emerson G. Wood, Lt. NOAA 

10.7 South Pole 

*Steven Kott, Lt. JG, NOAA 

George Engeman, Electronic Technician 

10.8 Samoa 

*Vernon T. Rumble, Station Chi ef 

*Donald W. Nel son , Physical Scientist 

*Contributors to the Summary Report 

126 
APPENDIX 

Mauna Loa Observatory Pyranometer History 

Measurements of horizontal incidence of hemispheric irradiance measurements at Mauna Loa Observatory began in October 1957 and have continued to 

the present. Eppley pyranometers were u sed (bulb type) until October 1975. 

Eppley Mod II pyranometers have been used since. Table A.l lists all the 

instruments. 

Table A .1 Pyranometers Used for Solar Radiation Records at 

Mauna Loa Observatory, Hawaii 

Instrument No. Type Date On Date Off 

3201 NWS bulb Jan. 1, 1958 Mar . 4, 1959 

2065 NWS bulb Mar. 5 , 1959 June 2, 1959 

2597 NWS bulb June 3 , 1959 July 1, 1960 

3201 NWS bulb July 2 , 1960 Feb. 25 , 1961 

3963 NWS bulb Mar. 4, 1961 Oct . 4, 1961 

3201 NWS bulb Oct. 5 , 1961 Oct . 9, 1961 

4215 NWS bulb Oct. 10, 1961 July 24' 1962 

3201 NWS bulb July 28 I 1962 Dec. 15, 1962 

1825 NWS bulb Dec. 15, 1962 Jan . 2 , 1964 

5269 NWS bulb Jan. 3, 1964 Jan. 14' 1964 

1825 NWS bulb Jan. 15, 1964 Feb. 3 , 1965 

1 833 NWS bulb Feb. 4, 1965 June 29 , 1974 

1825 NWS bulb Jan. 30, 1974 Sep . 29 , 1975 

12616 Eppley Mod II Sep. 30, 1975 Present 

Table A.2 contains the calibration records that are availabl e for these 

pyranometers. Of the NWS bulb types used, all sensors except instrument 

#2065 were coated with Parson's black. In the calibration procedure these 

pyranometers were compared with a lamp black coated standard under artificially generated incident light in an enclosed sphere . The temperature of 

calibration was 26.7°C. Later some of the Parsons black coated pyranometers 

were compared with a Parsons black coated standard in a similar manner. The 

calibration constants assigned to the working pyranometers were transferred 

from the lamp-black coated standard. The difference between sensitivity of 

the lamp-black coated instrument and the Parson's-black coated instrument is 

127 
Table A.2 Mauna Loa Observatory Pyranometer Calibration History 

Ser. No . Instr. Type Initial Cal. 

3201 

2065 

2597 

3963 

4215 

5269 

1825 

1833 

1 2616 

(P) 

(L) = 

NWS bulb (P) 2.32 (L) 

NWS bulb (L) 2 . 02 (L) 

NWS bulb (P) 2.39 (L) 

NWS bulb (P) No Records 

(7 .10) 

NWS bulb (P) No Records 

(7 .05 ) 

NWS bulb (P) 2.30 (L) 

NWS bulb (P) 2. 43 (L) 

NWS bulb (P) 1. 95 (L) 

Eppley Mod II 5. 54 

Parsons-black coated sensor 

Lamp-blac k coated sensor 

Date Terminal Cal. 

5.57 2.06 (L) 

1/58 No Records 

1/59 No Records 

No Records 

No Records 

9/63 2.04 (L) 

2.21 (P) 

2 .35 (L) 

9/62 2 . 23 (L) 

2.43 (P) 

8/58 1. 52 (L) 

1. 66 (P) 

? In Use 

Date 

7/73 

7/73 

7/73 

9/67 

1 2/75 

12/75 

1 2/75 

12/75 

In the calibration columns these letters indicate the type of standard 

instrument used in the calibration. 

Calibration constants are expressed in mv/langl ey 

The two numbers in parentheses in the calibration columns are the calibration 

constants stamped on the pyranometer. 

the "cross match factor ". After numerous comparison s an average difference 

of 7% ± 2% has been assigned as the cross match factor. The effect of the 

cross match factor is to decrease the values of the measured irradiance by 

7% ± 2% on the average if the comparison u sing the Parson ' s black standard is 

considered more representative. The Mauna Loa Observatory data have not been 

adjusted for the cross match factor. The crossmatch factor is not applicable 

to the Eppley Mod II pyranometer. 

Table A.2 also shows a decay in instrument sensiti vity with time for the 

Parson's black coated pyranometers. This decay i s expressed by the difference in the instrument sensitivity between the initial calibration and the 

terminal calibrati on. The rate of decay is unknown. No correction ha s been 

applied to the data to adjust for this decay in sensitivity. 

Besides being intercompared against a standard (which assigned the 

instrument sensitivity) some pyranometers were compared with other pyranometers on site at Mauna Loa Observatory under ambient conditions and clear 

ski es. Table A.3 lists these intercomparisons. Daily totals of the 

128 
Table A . 3 . Pyranometer Intercomparisons at Mauna Loa Observatory , Hawaii 

Period o f 

Compari son 

3/ 5/59 - 5/13/59 

6/ 5/59 - 6/24/59 

7/ 4/59 - 7/29/59 

8/ 1/59 - 8/11/59 

9/10/59 - 9/23/59 

10/ 8/59 - 10/23/59 

11/16/59 - 11/25/59 

1 2/ 3/59 - 12/31/59 

l/ 5/60 - 1/25/60 

4/23/60 - 4/24/60 

5/ 5/60 - 5/30/60 

6/12/60 

7/ 3/60 - 9/ 2/60 

4/12/61 - 5/ 8/61 

8/ 2/61 - 8/ 3/61 

11/17/61 - 11/27/61 

l/ 1/62 - 1/29/62 

2/ 3/62 - 2/22/62 

3/ 2/62 - 3/31/62 

4/ 1/62 - 4/29/62 

5/ 4/62 - 5/23/62 

6/ 4/62 - 6/24/62 

12/ 8/62 - 12/16/62 

10/16/63 - l0/31/63 

11/ 1/63 - 11/30/63 

1 2/ 1/63 - 12/17/63 

1 2/18/63 - 1/ 2/64 

l/ 3/64 - 1/10/64 

2/ 4/65 - 2/22/65 

7/ 1/74 - 7/ 8/74 

7/ 1/74 - 7/ 8/74 

8/ 8/75 - 8/25/75 

3/30/76 - 4/16/76 

x 

Greater Total 

(Instrument) 

2065 

2597 

2597 

2597 

2597 

2597 

~597 

2597 

2597 

2597 

2597 

2597 

2597 

3963 

3963 

4215 

4215 

4 215 

4215 

4215 

4215 

4215 

1825 

1833 

1833 

1833 

1825 

1833 

1833 

1 2616 

1825 

1825 

1 2616 

Note : x Ratios (Y) are of Daily Total s . 

Calibration 

Constant 

2 . 02 

2 . 39 

2 . 39 

2. 39 

2 . 39 

2 . 39 

2 . 39 

2 . 39 

2.39 

2 . 39 

2 . 39 

2.39 

2.39 

7 .10 

7 . 10 

7 . 05 

7 . 05 

7 . 05 

7 . 05 

7 . 05 

7 . 05 

7 . 05 

2 .43 

1. 95 

1. 95 

1. 95 

2 . 43 

1 . 95 

1.95 

5 . 54 

2 . 43 

2 . 43 

s. 54 

129 

y 

Lowe r Total 

(Instrument) 

3201 

3201 

3201 

3201 

3201 

3201 

'3201 

'3201 

3201 

1201 

3201 

3201 

3201 

3201 

3201 

3201 

3201 

3201 

3201 

3201 

3201 

1201 

3201 

1825 

1825 

1825 

5269 

5269 

1825 

12617 

12617 

12616 

12617 

Calibration 

Constant 

2 . 32 

2 . 32 

2 . 32 

2 . 32 

2.32 

2 . 32 

2 . 32 

2 . 32 

2 . 32 

2 . 32 

2 . 32 

2 . 32 

2 . 32 

2 . 32 

2 . 32 

2 . 32 

2 . 32 

2 . 32 

2 . 32 

2 . 32 

2 . 32 

/.. 32 

2 . 32 

2 . 43 

2 . 43 

2 . 43 

2 . 30 

2 . 30 

2 . 43 

5 . 65 

5 . 65 

5 . 54 

5 . 65 

x 

y 

1.04 

1.08 

1.08 

1. 09 

1. 09 

1.07 

1.08 

1.08 

1.06 

1.09 

1. 07 

1.10 

1.11 

1.02 

1.02 

1.02 

1.03 

1.02 

1. 04 

1.06 

1.07 

1.08 

1. 14 

1.01 

1.02 

1.02 

1. 02 

1.04 

1.04 

1.001 

1.051 

1. 0276 

1 . 006 
irradiance measured were u sed to o btain ratios between the two pyranome ters. 

The differences between the two pyranometers changed with solar angle (time 

of day). Figure A.l presents two examples of this. Such variations i n the 

differences between two pyranometers with the time of day (solar angle) were 

common. 

The response of the pyranometers at different ambient temperatures is 

another correction factor that has not been applied to the data collected. 

This temperature correction i s the measured difference in instrument r esponse 

at the ambient temperature of calibration (26.7°C) as compared with the response at the ambient temperature of operation out in the field . For the 

conditions at Mauna Loa Observatory, the ambient working temperature averages 

7. 2°C with a minimum of 0.0°C and a maximum of 14°C . Of the pyranometers 

used, those of the Eppley bulb type are the most temperature-sensitive. 

Tests at the NWS laboratories have shown that the average correction is 

0.144%/°C change in temperature. The correction i s such that the irradiance 

measured by the bulb pyranometers is high if the ambient temperature is below 

26.7°C. For Mauna Loa Observatory the average correction would be -2.8% 

with a maximum of -3.8% and a minimum of -1.8 . 

The final adjustment to the data obtained at Mauna Loa Observatory involves a r esolution of the scales used to a common scale based on an absolute 

measurement of sol ar energy. The NWS Eppley bulb pyranometer measurements of 

solar radiation at Mauna Loa Observatory are based on the Smithsonian scal e 

of 1913 with the IPS 1956 correction . The Eppl ey Mod II pyranometer measurements of solar radiation at Mauna Loa Observatory are based on the Angstrom 

standard of 1956. The difference between these two scales is ~3% with the 

scale used by the NWS Eppley bulb pyranometers being higher. The anticipated 

WMO primary standard scal e , which is based on absolute measurements of solar 

radiation using the PACRAD 3 instrument, is ~0.6% be l ow the scal e used by the 

NWS Eppl ey bulb pyranometers and ~2 .4 % higher than the scal e u sed by the 

Eppley Mod II pyranometer. Therefor e adjustments of -0.6 % and 2. % can be 

applied to the Eppl ey bulb pyranometer and Eppley Mod II pyranometer measurements of solar radiation respectively, to make them comparable with the 

anti cipated WMO standard and with each other. 

Figure A.l. Hourly ratios for 

pyranometez· intercomparisons, 

Mauna Loa Observatory, Hawaii. 

130 

125 

120 

115 

110 

105 

100 

095'---='01=---='=oa,.--,o:!-=- s---:1':-o __,.11,-----:'::12--:'::-13 - 1':-4 ---'15::---'=1s_...,. 11 _ _,_,1a 

True Solar Time 

130 
Table A.4 summarizes the corrections that can be applied to the measurements of solar radiation made at Mauna Loa Observatory. When there are no 

data available a "?" is entered or the average values are entered when they 

are applicable. 

Table A. 4 Surrunary of Corrections to Pyranometer Measurements of 

Solar Radiation Made at Mauna Loa Observatory 

Instr. 

Ser. No . 

3201 

Start 5/57 

End 7/73 

2065 

Start 1/58 

End ? 

2597 

Start 1/59 

End ? 

3963 

Start 

End 

4215 

Start 

End 

? 

? 

? 

? 

5269 

Start 9/63 

End 7/73 

1825 

Start 

End 

9/62 

12/75 

1833 

Start 8/58 

End 12/75 

12616 

Start ? 

Crossmatch 

Factor 

-7.0 

-7.0 

none 

none 

-7.0 

-7.0 

-7.0 

-7.0 

-7.0 

-7 . 0 

-7.0 

-7.7 

-7.0 

-8. 2 

-7. 0 

-8.4 

o.o 

Average 

Temperature 

Correction 

-2 . 8 

-2.8 

-2.8 

-2.8 

-2.8 

-2.8 

-2 .8 

-2.8 

-2.8 

- 2.8 

-2.8 

-2.8 

-2.8 

-2.8 

-2.8 

-2.8 

0.0 

Sensitivity Scale Net 

Decay Correction Correction 

0.0 

12.6 

? 

? 

? 

? 

? 

? 

? 

? 

o.o 

+12.7 

0 .0 

+ 9.0 

o.o 

+28.3 

o.o 

-0.6 

-0.6 

-0.6 

-0.6 

-0.6 

-0.6 

-0.6 

-0.6 

-0.6 

-0.6 

-0.6 

-0.6 

-0.6 

-0.6 

-0.6 

-0.6 

+2.4 

-10.4 

+ 2.2 

- 3.4 

- 3.4 

-10.4 

-10.4 

-10.4 

-10.4 

-10.4 

-10.4 

- 10.4 

+ 1.6 

-10.4 

- 2.6 

-10.4 

+16.5 

+ 2.4 

Note: Corrections are in Percent of the Original Data. 

131 ~ U. 5. GOVERNMEN T PRINTING OFFICE 1976 · 677·J47/ l29i