Dynamics of the outlet glacier : from processes to the application on a real glacier, the Astrolabe, East Antarctica

• Main Author: Drouet, Anne-Sophie
• Other Authors: Laboratoire de glaciologie et géophysique de l'environnement (LGGE), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Université de Grenoble, Emmanuel Le Meur, Gaël Durand
• Format: Doctoral or Postdoctoral Thesis
• Language: French
• Published: HAL CCSD 2012
• Subjects: Simulation; Data processing; Dynamic; Grounding line; Modélisation; Traitement données; Dynamique; Ligne d\'échouage; [SDU.STU]Sciences of the Universe [physics]/Earth Sciences; Antarc*; Antarctica; Antarctique*; East Antarctica; Ice Sheet
• Online Access: https://theses.hal.science/tel-00843026; https://theses.hal.science/tel-00843026/document; https://theses.hal.science/tel-00843026/file/Drouet.pdf

Two main contributions dominate the mass balance of Antarctica: surface mass balance, represented by all processes of gain and loss of mass acting at the upper surface (precipitations, melting, sublimation, wind transport.) and dynamical transport from grounded ice to the sea. This transfer takes place through outlet glaciers and represents 90% of the total loss of the whole ice sheet volume. These coastal systems act as regulators for the evolution of the ice sheet mass balance and for its contribution to sea level rise. Recently, observations emphasize a relevant decrease of mass balance in certain zones of Antarctica such as the West Coast, and an associated contribution to sea level rise from the ice sheet which increases significantly with respect to thermal expansion. Studying dynamics of outlet glaciers by modelisation thus participates at a better understanding of involved processes and enables to predict their response to any external sollicitations and to assess their potential impact on sea level budget. This work aims at providing with new elements for constraining these ice flow models for Antarctica. It is composed of two main parts. The first one concerns the implementation of physical processes into numerical models, in particular represented by grounding line migration, delimitating the grounded part from the floating one. It is based on 2 dimensionnal synthetic cases. The diversity of flow line ice sheet models is emphasized, with the associated differences and similarities. Most of these models lie on two strong assumptions, e.g. steadyness and dominance of basal sliding on ice flow, which are not always fulfilled. Moreover, the intercomparison work reveals discrepancies between models in terms of sea level contribution suggesting particular caution to be taken when considering corresponding results. Efforts have now to converge towards the validity of assumptions and on methods for implementing grounding line migration. The second part consists in applying the so-called 'full-Stokes' ...