Séminaire LJKModèles et Algorithmes Déterministes: MODANT

Le Mercredi 10 Novembre 2010 à 11h15 en Salle 1  Tour IRMA

Séminaire de Mr Marco PICASSO (Ecole Polytechnique Fédérale de Lauzanne)

Complexité des écoulements de glace (2/2)

Résumé:

Due to climatic change, many Alpine glaciers have significantly retreated during the last century. In this study we perform the numerical simulation of the temporal and spatial change of Rhonegletscher, Swiss Alps, from 1874 to 2007, and from 2007 to 2100.
Given the shape of the glacier, the velocity of ice u is obtained by solving a 3D nonlinear Stokes problem with a nonlinear sliding law along the bedrockice interface. The shape of the glacier is updated by computing the volume fraction of ice u, which satisfies a transport equation. The accumulation due to snow fall and the ablation due to melting is accounted by adding a source term to the transport equation.
A decoupling algorithm allows the two above problems to be solved using different numerical techniques. The nonlinear Stokes problem is solved on a fixed, unstructured finite element mesh consisting of tetrahedrons. The transport equation is solved using a fixed, structured grid of smaller cells.
The numerical simulation, from 1874 to 2007, is validated against measurements. Afterwards, three different climatic scenarios are considered in order to predict the shape of Rhonegletscher until 2100. A dramatic retreat of Rhonegletscher during the 21st century is anticipated. Our results contribute to a better understanding of the impact of climatic change on mountain glaciers.
