Measurement of Ice Sheet Internal Temperature Profiles with Ultra-Wideband Microwave Radiometry

The measurement of temperatures inside the Greenland and Antarctic ice sheets is important for modeling ice stiffness and therefore ice sheet dynamics and evolution. At present, information on these temperatures is available only from the small number of boreholes from which in-situ measurements can be obtained. A method for remotely sensing ice sheet internal temperatures has been under investigation in recent years through the use of ultra-wideband microwave radiometry. These efforts have shown that the measurement of ice sheet thermal emissions from 0.5-2 GHz can allow the determination of internal temperatures through a forward-model-based retrieval process. Measurements supporting these studies have been acquired by the Ultra-Wideband Software-Defined Microwave Radiometer (UWBRAD), which includes data processing methods specifically designed to address the high prevalence of radio frequency interference in the 0.5-2 GHz portion of the spectrum. This presentation will review recent progress in the retrieval of internal ice sheet information, including a report on results from the September 2017 airborne campaign over the Greenland ice sheet.

The presentation will review the ice sheet properties affecting low frequency microwave thermal emissions, including contributions from both ice sheet temperatures as well as the nuisance contributions of density fluctuations within the upper firn. Methods for constraining these parameters will also be presented, along with analyses and comparisons of alternate retrieval approaches to provide further assessment of the temperature errors obtained.

A detailed assessment of the science information available from existing datasets will also be provided, in particular with regard to the future use of the obtained information in ice sheet modeling analyses. Plans for continued measurements and applications will also be described.