GEOPHYSICAL CHARACTERISTICS OF AN ACTIVE ANTARCTIC SUBGLACIAL LAKE REVEALED BY GROUND PENETRATING RADAR

Satellite remote sensing techniques have recently identified several hundred active subglacial lakes under the ice in Antarctica. Water and sediment at the basal interface of glaciers and ice sheets provide the environment that supports microbial life as well as exerting primary control on ice dynamics. Thus a clear understanding of this system is of key importance to scientists in a range of disciplines. We have recently undertaken ground-based geophysical experiments to characterize one of these lakes in the lower trunk of Whillans Ice Stream in West Antarctica. Subglacial Lake Whillans is being studied as part of a multidisciplinary project called the Whillans Ice Stream Subglacial Access Research Drilling project (WISSARD) that will investigate the physical, geochemical and biological conditions at the base of the ice stream as water and sediment are transported from inland to the grounding line. We present data from ice-penetrating radar and GPS experiments that characterize basal conditions under Whillans Ice Stream including the distribution of water and sediment. Together with information from satellite remote sensing of the surface, we describe the evolution of the basal hydraulic system over the last decade as we prepare for lake access drilling in 2012-13.