The Evolution of an Antarctic Subglacial Lake from CryoSat Interferometric Altimetry
McMillan, Malcolm1; Corr, Hugh2; Shepherd, Andrew1; Ridout, Andrew3; Laxon, Seymour3
1University of Leeds, UNITED KINGDOM; 2British Antarctic Survey, UNITED KINGDOM; 3University College London, UNITED KINGDOM

Water at the base of an ice sheet plays an important role in ice sheet stability. The evolution of the subglacial hydrological system beneath the Antarctic Ice Sheet is, however, poorly understood. Here we map the surface expression of a drained subglacial lake in East Antarctica using the interferometric capability of the CryoSat altimeter. These observations enable the full area extent and depth of this feature to be mapped with unprecedented detail. We compare the CryoSat data to measurements made by the Ice, Cloud, and Land Elevation Satellite (ICESat) laser altimeter. By combining observations made from both platforms we chart the evolution of this surface feature and estimate the water volume which drained during a large outburst flood. This estimate is evaluated using independent observations of surface displacement made from Advanced Land Observing Satellite (ALOS) SAR imagery. This study demonstrates the capability of CryoSat to track off-nadir topographic features, and the contribution this mission can make to better understanding subglacial hydrology.