In the Quest of a Parametric Relation Between Ice Sheet Model Inferred Weertman's Sliding-Law Parameter and Airborne Radar-Derived Basal Reflectivity Underneath Thwaites Glacier, Antarctica

Abstract

Numerical ice sheet models use sliding laws to connect basal shear stress and ice velocity to simulate ice sliding. A sliding-law parameter β2 is used to control Weertman's sliding law in numerical ice sheet models. Basal reflectivity derived from ice-penetrating radar also provides information about frozen or thawed conditions underneath glaciers. To assess whether basal reflectivity can be used to constrain β2, we carry out statistical experiments between two recently published datasets: β2 inferred from three numerical ice sheet models (ISSM, Úa and STREAMICE) and airborne radar-derived relative basal reflectivity from the AGASEA-BBAS mission over Thwaites Glacier (TG). Our results show no robust correlation between the β2–relative reflectivity pair. Pearson's correlation coefficient, a test of linearity, ranges from −0.26 to −0.38. Spearman's correlation coefficient, which does not require a linear assumption, is also modest (∼−0.35). We conclude that β2 and relative basal reflectivity underneath TG do not infer similar basal conditions.