1.4.1. OPERATIONS

The CMDL South Pole Observatory (SPO) is located at the geographic South Pole at an elevation of 2835 m above sea level with an average temperature of -49C. SPO is part of Amundsen Scott Station, which is managed by the National Science Foundation (NSF) Office of Polar Programs.

Most CMDL projects are housed in the Clean Air Facility (CAF), an elevated building located upwind of the main South Pole Station. Construction of a replacement facility began in October 1995; the new building should be complete and ready for occupation by January 1997. Because the surface wind at the South Pole blows predominantly from the grid northeast, the SPO "Clean Air Sector" includes the area grid north of the CAF between grid 340 degrees and grid 110 degrees. Excursions into the Clean Air Sector are generally prohibited, with few exceptions.

SPO's meteorological instruments are mounted on the walk-up Met. Tower, which was located 100 m from the eastern side of the CAF. In November of 1995 the tower was moved to accommodate construction of the new CAF. Operations for the balloon program take place in three locations: the main station science building, the cargo arch, and the Balloon Inflation Tower (BIT). The cargo arch is used to inflate plastic balloons, that are too large to inflate and launch from the BIT.

Amundsen Scott Station is supplied by air. Because airplanes can only land at the Pole during the relatively warm months of October through February, the station is physically "closed" for 8 months each year. A midwinter "airdrop" took place in June of 1994 and 1995. Air samples collected during the austral winter cannot be returned for analysis until the following spring. Data are transferred digitally via satellite throughout the year. In January 1994, Amundsen Scott Station established a satellite link to the Internet, greatly facilitating the transfer of data.

During 1994 and 1995 there were occasional power outages and frequent "brownouts" because of an increasing demand for electrical power at the Pole. Within the CAF, science demands continue to exceed the "clean" power supplied by the building's uninteruptable power supply (UPS).

The University of Rome lidar was replaced by a similar instrument, owned and operated by the University of Illinois.

1.4.2. PROGRAMS

Table 1.6 is a summary of the measurement programs at SPO during 1994 and 1995. Operational highlights are as follows.

Carbon Cycle

The Siemens continuous carbon dioxide (CO₂) analyzer ran continuously without significant problems. Sample flask pairs were filled through the analyzer once per week and through a portable Martin and Kitzis Sampler (MAKS) unit twice per month.

Aerosols

The Meteorology Research, Inc. (MRI) four-wavelength nephelometer "hung" occasionally for unknown reasons. Discrete observations with the Pollak condensation nucleus counter (CNC), taken twice daily, generally agreed, as expected, with data from the Thermo Systems Inc. (TSI) CNC.

Solar and Terrestrial Radiation

During the summer, all Eppley pyranometers, pyrgeometers, and the tracking normal incidence phyrheliometer (NIP) ran continuously without significant problems. Discrete observations with the filter wheel NIP took place three times daily during especially clear conditions. In November 1995, a pyranometer equipped with a sun blocking disk was installed on the roof of the CAF. After sunset each March, the short-wave instruments were taken off-line for the winter.

Ozone and Water Vapor

The Dasibi ultraviolet absorption ozone monitor ran continuously without remarkable problems. Discrete observations with the Dobson ozone spectrophotometer took place three times daily during the summer and again during the darkest winter months using the full moon as a light source.

The ozonesonde program ran well during 1994 and 1995. Rubber balloons were launched from the balloon inflation tower (BIT) platform; the larger plastic balloons were inflated in the cargo arch and launched from the cargo yard. Launches usually occurred once per week except during the months of stratospheric ozone depletion (August-November) when the schedule was increased to every 3 days and then to every other day.

Nitrous Oxides and Halocarbons

The two Shimadzu Mini-2 electron capture gas chromatographs were inspected and upgraded in January 1994 and November 1994. Sample flask pairs were filled with ambient air twice per month whenever flasks were available.

Meteorology

The meteorology system was upgraded in January 1994 with all new sensors and a new data acquisition system. Manual weather observations took place daily at midnight universal time (UT).

Data Acquisition

The aerosol Control and Monitoring System (CAMS) unit was taken off-line during summer 1994.

Cooperative Programs

SIO. The Scripps Institution of Oceanography (SIO) conducts long-term monitoring of CO₂, ¹³C/¹²C ratio, and N₂O. Twice per month, three evacuated glass flasks were exposed to ambient air.

SIO. Three glass flasks were pressurized with ambient air on the first and fifteenth of each month for the long-term monitoring of O₂ and N₂.

DOE. The Department of Energy (DOE)conducts long-term monitoring of the spatial and temporal distribution of specific and anthropogenic radionuclides in surface air. The DOE pump ran continuously without significant problems; filters were replaced each week.

OGIST. Oregon Graduate Institute of Science and Technology (OGIST) monitors seasonal trends in the amount of chlorine-and bromine-containing trace gases in the Antarctic. Two flasks per week were filled with ambient air.

CSIRO. CSIRO monitors the ratio ¹³C/¹²C in atmospheric CO₂ for use in a 2-D global carbon cycle model. One glass flask was pressurized with ambient air every 2 weeks.

SUNY. Five air-filled cylinders remained on platforms approximately 800 m downwind of the main station for the quantification of the production rate of radiocarbon by galactic cosmic rays. The cylinders were inspected and cleared of snow once per month; no other operations were required for State University of New York (SUNY) . .

University of Arizona. An unsuccessful attempt was made to run a continuous meter during the winter of 1994 for the monitoring of H₂O₂ in the air/snow interface. In the summer of 1994 CMDL began collecting surface snow and micropit snow samples once per week.

TABLE 1.6. Summary of Measurement Programs at SPO in 1994-1995

Program			Instrument		Sampling Frequency
Gases
	CO2		Siemans IR analyzer		Continuous
	CO2, CH4		2.5-L glass flasks, through analyzer		1 pair twice mo-1
			2.5-L glass flasks, MAKS pump unit		1 pair twice mo-1
	Surface O3		Dasibi ozone meter		Continuous
	Total O3		Dobson spectrophotometer no. 82		3 day-1
	Ozone profiles		Balloonborne ECC sonde		1 wk-1, summer, autumn,
					winter; 1 (3 day)-1, spring
	Water vapor		Balloonborne sonde		10 times yr-1
	N2O, CFC-11, CFC-12, CFC-113, CH3CCl3, CCl4		300-mL stainless steel flasks		1 sample mo-1
	N2O, CFC-11, CFC-12, CFC-113, CH3CCl3, CCl4, SF6, HCFC-22, HCFC-141b, HCFC-142b, CH3Br, CH3Cl, CH2Cl2, CHCl3, C2HCl3, C2Cl4, H-1301, H-1211, H-2402, HFC-134a		850-mL stainless steel flasks		1 sample mo-1
	CFC-11, CFC-12, CFC-113, N2O, CH3CCl3, CCl4		Shimadzu automated GCs		1 sample h-1
Aerosols
	Condensation nuclei		Pollack CNC		2 day-1
			TSI CNC		Continuous
	Optical properties		Four-wavelength nephelometer		Continuous
Solar Radiation
	Global irradiance		Eppley pyranometers with Q and RG8 filters		Continuous, summer
			Eppley pyranometer with Q filter		Continuous, summer
			Net radiometer		Continuous, summer
	Direct irradiance		Eppley pyrheliometer with Q, OG1, RG2,		2 day-1
			and RG8 filters
			Eppley pyrheliometers with Q and RG8 filters		Continuous, summer
	Albedo		Eppley pyranometers with Q and RG8 filters		Continuous, summer
			filters, downward facing
Terrestrial (IR) Radiation
	Upwelling and downwelling		Eppley pyrgeometers		Continuous
Meteorology
	Air temperature		Platinum resistor, 2- and 20-m heights		Continuous
	Pressure		Capacitance transducer		Continuous
			Mercurial barometer		1 time wk-1
	Wind (speed and direction)		Bendix Aerovane		Continuous
	Frost-point temperature		Hygrometer		Continuous
Cooperative Programs
	CO2, 13C, N2O (SIO)		5-L evacuated glass flasks		2 mo-1 (3 flasks sample-1)
	Total surface particulates (DOE)		High-volume sampler		Continuous
					(4 filters mo-1)
	Various trace gases (OGIST)		Stainless-steel flasks		1 week-1 (2 flasks set -1), summer only
	Interhemispheric 13C/14C (CSIRO)		5-L glass flasks		1 or 2 flasks mo-1
	O2, N2 (Scripps)		Air sampling pump and flasks		1 mo-1 (3 flasks set-1)
	H2O2 (Univ. of Arizona)		Snow sample collection		1 time wk-1
	Isotope production (SUNY)		Pressurized cylinders		N/A; checked once mo-1

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