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Data Set ID:
NSIDC-0097

Decadal-Length Composite West Antarctic Air Temperature Records, Version 1

This data set includes daily, monthly, and yearly mean surface air temperatures for four interior West Antarctic sites between 1978 and 1997. Data include air surface temperatures measured at the Byrd, Lettau, Lynn, and Siple Station automatic weather stations. In addition, because weather stations in Antarctica are difficult to maintain, and resulting multi-decade records are often incomplete, the investigators also calculated surface temperatures from satellite passive microwave brightness temperatures. Calibration of 37-GHz vertically polarized brightness temperature data during periods of known air temperature, using emissivity modeling, allowed the investigators to replace data gaps with calibrated brightness temperatures.

MS Excel data files and GIF images derived from the data are available via ftp from the National Snow and Ice Data Center.

Geographic Coverage

Spatial Coverage:
  • N: -82.52, S: -82.52, E: -174.45, W: -174.45

  • N: -80.01, S: -80.01, E: -119.4, W: -119.4

  • N: -75.9, S: -75.9, E: -84, W: -84

  • N: -74.21, S: -74.21, E: 160.41, W: 160.41

Spatial Resolution: Not Specified
Temporal Coverage:
  • 25 October 1978 to 31 December 1997
Temporal Resolution: Not specified
Parameter(s):
  • Atmospheric Temperature > Air Temperature
  • Atmospheric Temperature > Surface Air Temperature
Platform(s) DMSP, NIMBUS-7
Sensor(s): AWS, SMMR, SSM/I
Data Format(s): Not specified
Version: V1
Data Contributor(s): Christopher Shuman, Charles Stearns

Data Citation

As a condition of using these data, you must cite the use of this data set using the following citation. For more information, see our Use and Copyright Web page.

Shuman, C. A. and C. R. Stearns. 2006. Decadal-Length Composite West Antarctic Air Temperature Records, Version 1. [Indicate subset used]. Boulder, Colorado USA. NSIDC: National Snow and Ice Data Center. doi: http://dx.doi.org/10.7265/N55D8PS0. [Date Accessed].

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Detailed Data Description

Format and File Sizes

Three MS Excel files are available: "shuman_daily_means.xls" (741 KB) contains daily mean temperatures; "shuman_monthly_means.xls" (35 KB) contains monthly mean temperatures; and "shuman_annual_means.xls" (14 KB) contains annual mean temperatures. Two GIF images are also available: annual_avg.gif (332 KB) and daily_avg.gif (677 KB) are plots depicting the data.

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Spatial Coverage

Measurements are available for the following automatic weather station sites:

  • AWS Siple Station (75.90º S, 84.00º W)
  • AWS Byrd (80.01º S, 119.40º W)
  • AWS Lettau (82.52º S, 174.45º W)
  • AWS Lynn (74.21º S, 160.41º E)
Study Area Location Map:

Letters indicate the approximate locations of AWS Siple Station (S), AWS Byrd (B), AWS Lettau (L), and AWS Lynn (Y).

Map: Location of AWS sites

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Temporal Coverage

Different coverages are available for each site. The Siple Station and Byrd records begin 25 October 1978, the Lettau record begins 1 January 1986, and the Lynn record begins 10 July 1987. All records end 31 December 1997.

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Parameter or Variable

Data files contain the following fields: dates; air temperatures measured at automatic weather stations (AWS TA), given in kelvins (K); and "composite" air temperatures (COMP TA) incorporating calibrated satellite passive microwave brightness temperatures, given in kelvins (K).

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Software and Tools

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Data Acquisition and Processing

AWS data were obtained from 3-hourly files on the anonymous FTP site operated by the University of Wisconsin (ftp://ice.ssec.wisc.edu/pub/). The investigators derived daily average values for comparison with brightness temperatures (see below). Information about the AWS units used for air temperature measurements is available at the Antarctic Automatic Weather Stations Project Web site, and is also provided by Stearns et al. (1993) and Stearns and Weidner (1993).

Because weather stations in Antarctica are difficult to maintain, and resulting multi-decade records are often incomplete, the investigators also calculated surface temperatures from satellite passive microwave brightness temperatures (Tbs). Tbs are functions of many characteristics of the surfaces they describe. In areas covered by dry snow, Tbs effectively represent the physical temperature of the near-surface snow, mulitiplied by its emissivity. Thus Tbs cannot be directly substituted for missing AWS temperature measurements, but must first be calibrated to account for variations in snow emissivity.

To create this data set, the investigators compiled daily-averaged, vertically-polarized 37-GHz Tbs from the Scanning Multichannel Microwave Radiometer (SSMR) and Special Sensor Microwave/Imager (SSM/I; see NSIDC's DMSP SSM/I-SSMIS Daily Polar Gridded Brightness Temperatures). Brightness temperatures were then compared with temporally equivalent near-surface air temperatures (measured by AWS) to calculate emissivity. Modeled emissivity time series were then used to convert the longer, continuous Tb records into calibrated near-surface air temperatures. Please consult Shuman and Stearns (2001) for more information.

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References and Related Publications

Contacts and Acknowledgments

Christopher A. Shuman
Earth System Science Interdisciplinary Center
University of Maryland
College Park, MD   20742
USA

Charles R. Stearns
Space Science and Engineering Center
University of Wisconsin
Madison, WI   53706
USA

Acknowledgements: 

This research was supported by NSF grant OPP-9526566 ("Passive Microwave Remote Sensing for Paleoclimate Indicators at Siple Dome, Antarctica") and NASA EOS-IDS grant MTPE-00027. The Antarctic Automatic Weather Stations Project staff provided valuable assistance.

Document Information

Document Creation Date:

09 April 2002

Document Revision Date:

26 April 2002

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