Interaction between ice sheet dynamics and subglacial lake circulation: a coupled modelling approach
- 1Bavarian Academy and Sciences, Commission for Glaciology, Alfons-Goppel-Str. 11, 80539 Munich, Germany
- 2Alfred Wegener Institute for Polar and Marine Research, Bussestrasse 24, 27570 Bremerhaven, Germany
- 3Laboratoire de Glaciologie, Département des Sciences de la Terre et de l'Environnement (DSTE), Université Libre de Bruxelles (ULB), CP 160/03, Avenue F.D. Roosevelt, 1050 Bruxelles, Belgium
Abstract. Subglacial lakes in Antarctica influence to a large extent the flow of the ice sheet. In this study we use an idealised lake geometry to study this impact. We employ a) an improved three-dimensional full-Stokes ice flow model with a nonlinear rheology, b) a three-dimensional fluid dynamics model with eddy diffusion to simulate the basal mass balance at the lake-ice interface, and c) a newly developed coupler to exchange boundary conditions between the two individual models. Different boundary conditions are applied over grounded ice and floating ice. This results in significantly increased temperatures within the ice on top of the lake, compared to ice at the same depth outside the lake area. Basal melting of the ice sheet increases this lateral temperature gradient. Upstream the ice flow converges towards the lake and accelerates by about 10% whenever basal melting at the ice-lake boundary is present. Above and downstream of the lake, where the ice flow diverges, a velocity decrease of about 10% is simulated.