Investigating Basal Friction Under the Antarctic Ice Sheet Using a New Generation Subglacial Hydrology Model.

Abstract:

Constraining the basal conditions of continental ice sheet is an important step toward improving the projections of the contribution of ice sheets to sea level rise. Inferring basal conditions, and more specifically the friction coefficient, at the ice/bed interface remains challenging due to the lack of direct observations of the sliding of continental ice masses. The most advanced way to derive basal friction is to rely on inverse methods using remotely sensed surface velocities. While efficient, these methods lump all the uncertainties of the model and input data into basal friction in order to reproduce the InSAR derived velocities. Here, we investigate a new approach that consists of using a more physical method to infer basal conditions by relying on a new generation large scale subglacial hydrological model implemented in the ISSM framework (de Fleurian et al 2014). We investigate the calculated effective pressure and its correlation with a pattern of basal drag inferred by an inverse method at the continental scale. We then discuss the ability of the hydrologically derived basal conditions to reproduce the measured surface velocities.