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Geophysical monitoring for climaticSOUTH POLE

N WIND ROSE

change, Amundsen-Scott South Pole79

Station, 1979-1981

GREGORY M. SIEDELBERG

NOAAlEnvironmental Research LaboratoriesGeophysical Monitoring for Climatic Change

Boulder, Colorado 80303

The Geophysical Monitoring for Climatic Change (GMCC)

program maintains four remote baseline stations, includingone at the Amundsen-Scott South Pole Station. Part of the AirResources Laboratories of the National Oceanic and Atmo-spheric Administration (NOAA), the GMCC program monitorslevels of various atmospheric trace constituents to determineany changes in background levels relevant to climatic changeand the anthropogenic impact related to those changes. Duringthe 1979-80 season, carbon dioxide, surface ozone, solarradiation, aerosols, meteorology, and halocarbons were mon-itored continuously. A Data General (NOVA 1220) computerwas used for control, scaling, and data logging of the instru-ment measurements (Herbert et al. 1981). Also, GMCC main-tained cooperative programs with the U.S. Department ofEnergy, Scripps Institution of Oceanography, the State Uni-versity of New York at Albany, the University of Maryland,the University of Arizona, NOAA Air Resources Labs, and theUniversity of California at Los Angeles. GMCC activities arecarried out at the Clean Air Facility (CAF), located 90 metersupwind from the main station, in order to minimize localcontamination.

During the 1978-79 season the program was operated byLuG J . C. Bortniak, NOAA Corps (observer) and C. Smythe(engineer). In November 1979 they were relieved by LTJG W.

L. Hiscox, NOAA Corps, and G. M. Siedelberg, respectively.This article gives a brief description of the continuous and

discrete measurement activities of CMCC.

1. Meteorology. Measurements were made of wind speedand direction, pressure, moisture, air temperature, and snowtemperature. The wind and temperature sensors are locatedon a 10-meter tower 30 meters grid 00 from the CAF. Continuousatmospheric moisture measurements were made with aDupont 303 moisture monitor provided by the State Universityof New York. The mean temperature from November 1979through October 1980 was —49.5°C, with a low of —74.2°C anda high of —19.2°C. Mean wind direction was 045° and meanwind speed was 9.7 knots, with a maximum wind of 40 knots.The maximum wind chill factor was —118.3°C. A wind rose ofthe surface winds at the Clean Air Facility is shown in figure1. The steadiness of the surface wind is readily seen.

2. Aerosols. Continuous measurements of the number con-centrations of aerosols were made using a modified GeneralElectric condensation nuclei counter. Until late January 1980,a four-wavelength nephelometer was used to measure the scat-tering properties of aerosols. This marks the first time thescattering properties of aerosols have been measured at theSouth Pole (see figure 2). Discrete measurements of Aitkennuclei concentrations were made three times a day in thesummer and two times a day in the winter months with aPollack counter (Bodhaine and Murphy 1980). A long-tubeGardner counter also was used, but it proved ineffective in the

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WIND FREQ.S

Figure 1. Wind rose for the South Pole observatory in 1979 (Herbert1980, p. 54). M/S = meters per second.

midwinter months of May through August; during thesemonths, concentrations of surface aerosols are reduced whena strong surface temperature inversion prevents good verticalmixing with aerosol-enriched air aloft.

3. Carbon dioxide. The Uras 2T CO 2 non-dispersiveinfrared analyzer was put back on line in November 1979 andwas used for continuous carbon dioxide (CO2) measurementsthroughout 1980. Also, 0.5-liter flasks were aspirated by hand

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Figure 2. Daily geometric mean condensation nuclei concentration(bottom), four wavelength aerosol light scattering (middle), andangstrom exponent (top)for 1979 at the South Pole. Note the eventthat occurred in early August and the corresponding large peak inlight scattering, which suggests that there were increases in thelarger atmospheric aerosols that cause high light scattering.

1981 REVIEW 193

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and by vacuum pump at regular intervals. In March 1980 aCO2-in-air reference tank was added to the weekly calibrationas a surveillance gas.

daily using a sun photometer at 380- and 500-nanometer wave-lengths.

4. Ozone. During the austral summer, total ozone measure-ments were taken three times a day at the South Pole using aDobson spectrophotometer. Focused moon observations weremade when possible during the austral winter. Surface ozonemeasurements were made continuously using a Dasibi pho-tometer.

5. Solar radiation. Solar irradiance was monitored contin-uously using four Eppley global pyranometers with quartz,GG-22, OG-1, and RG-8 Schott glass hemispheric filter domes,an Eppley ultraviolet pyranometer with diffusing disk and anEppley normal incidence pyrheliometer mounted on a solartracker (see figure 3). In addition, discrete measurements weremade three times daily using a pyrheliometer with a rotatingfilter wheel containing quartz, OG-1, RG-2, and RG-8 filters.Discrete measurements of turbidity were also made three times

6. Halocarbons. Three-hundred-milliliter flasks were usedto collect samples of CFC-11, CFC-12, and nitrous oxide oncea week in summer and twice a month in winter for analysis atthe NOAA GMCC central laboratory in Boulder.

7. Instrument Control and Data Acquisition System (IcDAs).Continuous measurements are fed into ICDAS for real-timescaling and then are transferred to magnetic tape for transportto Boulder. In addition, ICDAS initiates and monitors instru-ment calibrations. Through the use of preventive maintenanceand a well-stocked spare parts supply, ICDAS had an onlineefficiency of 98.9 percent.

The building facility housing the GMCC program at the SouthPole is supported by the National Science Foundation. For areview of all GMCC activities see Herbert (1980). Data from pastyears have been archived and are available from the WorldData Center in Ashville, North Carolina.

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Figure 3. Solar irradiance of the normal Incidence pyrheliometer (NIP) for a 5-day period, from 1 through 5 November 1980. The lowestexcursions represent shadows cast on the NIP from sampling stacks on the roof of the Clean Air Facility. MW/CM xX2 = milliwatts persquare centimeter.

194 ANTARCTIC JOURNAL

References

Bodhaine, B. A., and Murphy, M. E. 1980. Calibration of an automaticcondensation nuclei counter at the South Pole. Journal of AerosolScience, 11, 305-312.

Herbert, G. A. (Ed.). 1980. Geophysical monitoring for climatic change(Summary Report 8, 1979). Boulder, Cob.: U.S. Department of Com-

merce, National Oceanic and Atmospheric Administration, Envi-ronmental Research Laboratories.

Herbert, C. A., Harris, J . M., Johnson, M. S., and Jordan, J . R. 1981.The acquisition and processing of continuous data from GMCC

observatories (N0AA Technical Memorandum ERL ARL-93). SilverSpring, Md.: U.S. Department of Commerce, National Oceanic andAtmospheric Administration, Environmental Research Laborato-ries.

Atmospheric processes and energytransfers at the South Pole

JOHN J . CARROLL

Department of Land, Air, and Water ResourcesUniversity of CaliforniaDavis, California 95616

During the past year I continued several aspects of a studyof the lower atmosphere at the South Pole, as reported inprevious issues of this journal (see, e.g., Carroll 1980). Theinvestigation of surface albedos has been extended to considerthe effect of periodic surface macroscale structures (i.e., rip-ples) on the effective shortwave albedo of liquid water andsnow surfaces (Carroll 1981b). Preliminary results of this workindicate that at low latitudes, the effect of surface ripples is toincrease weakly the effective albedo. At high latitudes, a rip-pled surface absorbs significantly more radiation than does aflat surface. The magnitude of the effect depends on theamplitude of the ripples, the dependence of the surface reflec-tivity on angle of incidence of the radiation, and the orienta-tion of the axis of the ripples.

I have completed analysis of the mean energy balance com-ponents and related atmospheric variables and parametersobtained between March 1975 and December 1977. A descrip-tion of all data processing procedures has been prepared (Car-roll 1981c) and tables of daily mean values of these quantitieshave been published (Carroll and Eby 1981).

I have continued efforts to model the atmospheric boundarylayer/snow layer energy transfer processes and have revisedthe prototype model reported previously (Carroll and Fitzjar-rald 1979), and am now comparing model predictions and areal sequence of events recorded at the South Pole. The modelis driven by the pressure gradient determined from theobserved, time-dependent, 500-millibar wind, the observed

changes in surface net radiation, and the observed snow tem-perature at 100 centimeters. Initial fields are established frommeasured snow temperature profiles, air temperature andwind profiles to 8 meters, and radiosonde temperature andwind data up to 500 millibars. Preliminary results (Carroll1981a) indicate that the surface fluxes of heat and momentumvary in the correct sense, but with less amplitude than thoseestimated from surface layer observations. A major discrep-ancy is that the turbulence model rapidly reduces the temper-ature gradient in most of the outer layer, whereas this is notgenerally observed.

This work was supported by National Science Foundationgrants DPP 77-19362 and DPP 80-90525.

References

Carroll, J. J. 1980. Surface energy exchange at the South Pole. AntarcticJournal of the U.S., 15(5), 180-182.

Carroll, J . J . 1981. A comparison of model calculations with real behaviorof a time dependent, cloud free stable planetary boundary layer. Paperpresented at the Third Scientific Assembly, International Associa-tion of Meterology and Atmospheric Physics/International Union ofGeodesy and Geophysics, Hamburg, Germany, August 1981. (a)

Carroll, J . J . 1981. The effect of surface striations on the absorption of shortwave radiation. Paper presented at the Third Scientific Assembly,International Association of Meteorology and Atmospheric Physics!International Union of Geodesy and Geophysics, Hamburg, Ger-many, August 1981. (b)

Carroll, J . J . 1981. South Pole energy balance experiment: Data processingquality control and general results (Contributions to AtmosphericScience 16). Davis: University of California. (c)

Carroll, J . J . , and Eby, E. B. 1981. South Pole energy balance experiment:Tabulations of daily mean energy components and conditions (Contri-butions to Atmospheric Science 17). Davis: University of California.

Carroll, J . J . , and Fitzjarrald, D. E. 1979. Atmosphere-surface interactionsin the unsteady, stable planetary boundary layer. Paper presented atthe International Committee on Polar Meteorology Symposium onProgress in Antarctic Meteorology, 17th General Assembly of theInternational Union on Geodesy and Geophysics, Canberra, Aus-tralia, December 1979.

1951981 REVIEW