Basal processes of glaciers and ice-streams

Titre : Basal processes of glaciers and ice-streams

Laboratoire de rattachement : LGGE

Encadrant : Olivier Gagliardini

Téléphone : 04.76.82.42.76

Mots clés : basal ice, finite-element ice flow model Elmer/Ice

Contexte et objectifs de la mission de stage :

The decrease of friction at the base of glaciers is one of the processes invoked to explain the currently observed acceleration of outlet glaciers in Greenland. Basal processes are also known to strongly control the daily and seasonal speed variations of Alpine type glaciers. Water, produced either by surface runoff during summer or deformational and frictional heats all around the year, has the capacity to modulate the local bedrock friction by opening cavities and channels. When cavities grow, contact area between ice and rock is decreased and so the friction. The cavity layer has only the potential to drain a small amount of water, generally associated with high water pressure. If water quantities are large enough, discrete features like channels are created, with the capacity to drain larger water quantities. A model accounting for the coupling between the cavity layer mean thickness, the channel cross-sectional area and the water pressure has been implemented in the finite element ice-sheet model Elmer/Ice (http://elmerice.elmerfem.org/). Elmer/Ice also includes the ice flow equations (Stokes equations) as well as a water pressure dependent friction law.
Using these recent developments, the objective of this internship is to model the coupling between the basal hydrology (distribution of the basal water pressure) and the ice flow for different bedrock topography configurations. You will also apply the coupled model to real data on selected sites for which we have information for both the ice flow and the hydrological system.
To perform this work, you must have strong background in modelling and programming and a real interest in conducting geophysical simulations.