Numerical thermo-mechanical model of an icefield with subglacial lake. A test case in Svalbard, Arctic

In this work we present a mathematical model for the description of the dynamical and thermodynamical evolution of a system consisting of an icefield locally underlaid by a subglacial lake occupying a bed depression. The representation of the phase change ice-water is the clue of the model. The numerical solution is based on a finite volume technique. The computational code is tested to describe a portion of the Amundsenisen Icefield, South-Spitsbergen, Svalbard, where the existence of subglacial lake has been hypothesized. The contribution of firn and snow upper layers to the system in terms of temperature fied, density and water content is shown to be non-negligible in the modelling, as it supports ice to overcome its metastable state and change into liquid phase thus forming the subglacial lake. Lake cavity depth (or, better, the bottom surface area) appears to be critical for the formation of the lake, being directly proportional to the amount of geothermal heat coming in. Numerical simulation results are consistent with the existence of the conjectured subglacial lake within the environmental conditions fixed to measured data. Improvements of ice water content modelling and boundary condition formulation are in progress.