Remote Sensing of Ice Sheet Internal Temperatures Using Ultra-Wideband Microwave Radiometry

Information on ice sheet internal temperatures is important for understanding ice sheet dynamics and evolution. At present, ice sheet internal temperature information is available only from borehole measurements or from model predictions. The development of methods for remotely sensing internal ice sheet temperatures is therefore desirable.

Microwave radiometry provides a means for sensing the internal temperature of a medium, because the thermal noise radiated by a portion of the medium is directly proportional to its physical temperature. The total thermal noise measured by the radiometer then is a combination of the emissions from all portions of the medium, with attenuation and reflection along the propagation path to the observing radiometer taken into account. Because the attenuation through an ice sheet varies with the electromagnetic frequency of the observing radiometer, a combination of frequencies can be used to resolve temperature information within the ice sheet as a function of depth.

The presentation will review progress in this methodology achieved by the measurements of the ultra-wideband software-defined radiometer (UWBRAD), which provides measurements of Earth surface thermal emissions over the frequency range 0.5-2 GHz. UWBRAD was deployed in airborne measurement campaigns in Greenland (September 2016 and September 2017) as well as in Antarctica (November-December 2018). Results on ice sheet internal temperature measurements from these campaigns will be presented and discussed. Future prospects for continued development of this technology will also be summarized.