Thermal Refraction: Impactions for Subglacial Heat Flux

Summary Numerical models of glaciers suggest variations in geothermal heat flux influences basal melting. In this study, we demonstrate the effect of thermal refraction on heat flux variations at the glacial-basement interface using a finite difference approximation of the 2D, steady-state, heat flow equation. Thermal refraction occurs as a result of variations in subglacial topography where the thermal conductivity of glacial ice and the solid Earth differ, or in the absence of subglacial topography where contacts between differing conductivity rocks exist. Both models are incompatible with prior topographic-based models of subglacial heat flux. Heat flux can preferentially flow into or around a subglacial valley depending on the thermal conductivity contrast with surrounding rock, with magnitudes at the glacial-basement interface ±20 to 40% of regional geothermal heat flux.