Documentation: Decadal-Length Composite West Antarctic Air Temperature Records (C. Shuman)

Decadal-Length Composite West Antarctic Air Temperature Records (C. Shuman)

Data Set Summary

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.

Citing These Data:

Please cite these data as follows:

Shuman, C.A., and C.R. Stearns. 2002. Decadal-length composite West Antarctic air temperature records. Boulder, CO: National Snow and Ice Data Center. http://dx.doi.org/10.7265/N55D8PS0.

Also, please consult and cite the following related publication:

Shuman, C.A., and C.R. Stearns. 2001. Decadal-length composite inland West Antarctic temperature records. Journal of Climate 14:1977-1988.

Overview Table

Category	Description
parameter(s)	surface air temperature
spatial coverage	West Antarctica
temporal coverage	October 1978 through December 1997
data format	MS Excel files and GIF images
file sizes	file sizes range from 14 KB to 741 KB
procedures for obtaining data	Data are available via FTP.

1. Contacts and Acknowledgments
2. Detailed Data Description
3. Data Access and Tools
4. Data Acquisition and Processing
5. References and Related Publications
6. Document Information
Derived Images with explanatory captions are also available.

1. Contacts and Acknowledgments:

Investigator Name(s) and Affiliation(s):

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

Technical Contact:

NSIDC User Services
National Snow and Ice Data Center
CIRES, 449 UCB
University of Colorado
Boulder, CO 80309-0449 USA
phone: +1 303.492.6199
fax: +1 303.492.2468
form: Contact NSIDC User Services
e-mail: nsidc@nsidc.org

Acknowledgments:

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.

2. 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.

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

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.

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).

3. Data Access:

Data are available via FTP.

Related Data Collections:

4. 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.

5. References and Related Publications:

Maslanik, J.A., J.R. Key, and R.G. Barry. 1989. Merging AVHRR and SMMR data for remote sensing of ice and cloud in polar regions. International Journal of Remote Sensing 10:1691-1696.

Shuman, C.A., R.B. Alley, S. Anandakrishnan, and C.R. Stearns. 1995. An empirical technique for estimating near-surface air temperatures in central Greenland from SSM/I brightness temperatures. Remote Sensing of the Environment 51:245-252.

Shuman, C.A., and C.R. Stearns. 2001. Decadal-length composite inland West Antarctic temperature records. Journal of Climate 14:1977-1988.

Stearns, C.R., L.M. Keller, G.A. Weidner, and M. Sievers. 1993. Monthly Mean Climatic Data for Antarctic Automatic Weather Stations. Antarctic Research Series, American Geophysical Union, Vol. 61:1-21.

Stearns, C.R., and G.A. Weidner. 1993. Sensible and Latent Heat Flux Estimates in the Antarctic. Antarctic Research Series, American Geophysical Union, Vol. 61:109-138.

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Decadal-Length Composite West Antarctic Air Temperature Records (C. Shuman)

Data Set Summary

Citing These Data:

Overview Table

Table of Contents

1. Contacts and Acknowledgments:

Investigator Name(s) and Affiliation(s):

Technical Contact:

Acknowledgments:

2. Detailed Data Description:

Format and File Sizes:

Spatial Coverage:

Study Area Location Map:

Temporal Coverage:

Parameter or Variable:

3. Data Access:

Related Data Collections:

4. Data Acquisition and Processing:

5. References and Related Publications:

6. Document Information:

Document Creation Date:

Document Revision Date:

Document Curator:

Document URL:

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