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Stabilizing effect of pinning points beneath an ice shelf

par Stages - 13 septembre 2013 ( maj : 7 mai 2014 )

Titre : Stabilizing effect of pinning points beneath an ice shelf

Laboratoire de rattachement : LGGE

Encadrant : Gaël Durand

Téléphone : 04 76 82 42 84

Mots clés : Ice rises, Damage Mechanics, Elmer/Ice

Mass balance of Antarctic outlet glaciers is dominated by a complex coupled system between grounded ice (ice sheet) and floating ice (ice shelf). The West Antarctic Ice Sheet (WAIS) accounts for the largest area of floating ice-shelves, such as Ronne and Ross ice shelves. Ice flow in these areas is mainly dictated by longitudinal stretching tending to accelerate the flow near the terminus and triggering iceberg calving. However, other processes on ice shelves slow down the ice flow, i.e. lateral friction on the rocky-margins or basal friction over pinning points. These latter are created by the presence of seamounts over which the floating tongue can become grounded and such lead to the formation of an ice rise. Today, these pining points are not clearly taken into account when representing ice flow, leading to a distorted representation of the ice dynamics over these areas.

At the Laboratoire de Glaciologie et de Géophysique de l’Environnement (LGGE), we are developing a finite element ice-flow model « Elmer/Ice » dealing with all stresses in the ice (http://elmerice.elmerfem.org/). In addition, a damage mechanics model has been developed, able to represent the development of fracture density at the meso-scale. The aim of this internship is to apply damage mechanics on 3D-synthetical geometries to investigate the stabilizing effect of ice-rises on the ice flow, using a parallel computing environment. It will help us to validate the damage model and to better represent the effect of pinning points on ice-shelves dynamics. This work requires background in modeling and an interest in climate research in general and polar sciences in particular.

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