HR: 14:25h
AN: C43A-04    [Abstracts]
TI: Inferring the surface shape of the ice sheet-ice shelf transition zone using a full-Stokes model.
AU: * Durand, G
EM: durand@lgge.obs.ujf-grenoble.fr
AF: LGGE, 54, rue Molière BP 96 Domaine Universitaire, Saint Martin d'Hères, F-38402, France
AU: Gagliardini, O
EM: gagliar@lgge.obs.ujf-grenoble.fr
AF: LGGE, 54, rue Molière BP 96 Domaine Universitaire, Saint Martin d'Hères, F-38402, France
AB: Grounding line migration plays an important role in the stability of marine ice-sheets such as the West Antarctica ice sheet. For modelling purpose, it is generally assumed that the grounding line position, as well as its stability, is determined by the floating condition constrained by the sea water level. With such approach, the vertical position of the sea-ice interface depends only on the ice thickness at this place, so that the non-hydrostatic part of the stress within the ice does not play any role. In this presentation, the floating condition is compared with the solution for which the sea water action is modelled by the buoyancy pressure. In the proposed method, the sea- ice interface is treated as a free surface submitted to the buoyancy sea pressure. The starting point of this surface, i.e. the grounding line, is determined by solving a contact problem. The full-Stokes equations, the air/ice free surface as well as the sea/ice free surface equations are solved in a coupled way with the finite element code Elmer. The resulting free surface is compared to measured surfaces. As observed, the modelled ice thickness at the grounding line is found to be greater than that of the floating ice in hydrostatic equilibrium. Moreover, the particular depression of the air/ice surface downstream the grounding line is also well reproduced by our model, which is in full agreement with topographic observations.
DE: 0720 Glaciers
DE: 0728 Ice shelves
DE: 0730 Ice streams
DE: 0774 Dynamics
DE: 0776 Glaciology (1621, 1827, 1863)
SC: Cryosphere [C]
MN: 2007 Fall Meeting