Composite Ice Sheet Temperature Record From In Situ and Satellite Data Sets, Siple Dome, West Antarctica

During December 1996, ice core drilling activities were begun at Siple Dome, West Antarctica. In January 1997, the University of Wisconsin installed an automatic weather station (AWS) at Siple Dome as part of its Antarctic Meteorological Research Center?s (http://uwamrc.ssec.wisc.edu/aws/) network of instruments. A multi-year to decadal-length temperature record is needed to accurately calibrate ice core proxy temperature data (stable isotopes of hydrogen and oxygen) among other things. As part of an ongoing research activity, a composite temperature record has been developed using infrared temperatures (TIR) and passive microwave brightness temperatures (TB) in conjunction with near-surface measurements (TA) from the AWS. The intent of this research was to define a new technique that can be applied at other Antarctic and Greenland sites. This effort builds on a published emissivity modeling technique that uses TA and TB data (e.g. Shuman et al., 1995) and recently developed TIR data (e.g. Comiso 2000). All three data types have various limitations: 1) the TA record is relatively short and may have data gaps; 2) the TIR record requires calibration and has data gaps due to clouds; and 3) the TB record requires calibration especially due to periods of emissivity variability related to melt events. Emphasis was also placed on understanding the uncertainty of the resulting temperature record so that confidence in these data could be maximized. The resulting data set provides a daily-average temperature time series for the Siple Dome site with constrained uncertainties. It effectively minimizes the limitations of all three types of input data. The time series covers more than 20 years as it begins in 1981 and extends through 2001. Daily, monthly, seasonal, and annual average values have been calculated and trend analysis has been conducted.