A thermo-mechanical model of evolution for the glacial Antarctic basin Vostok - Byrd Glacier : Sensitivity to poorly known parameters.

• Main Author: Ritz, Catherine
• 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 Joseph-Fourier - Grenoble I, Louis Lliboutry; Jean Jouzel
• Format: Doctoral or Postdoctoral Thesis
• Language: French
• Published: HAL CCSD 1992
• Subjects: Antartique; modélisation écoulement; forage; modèle géometrie imposée; dôme; profils verticaux; couplage vitesse-température; glacier Byrd; Vostock; modèle thermo-mécanique; modèle ice-shelf; [SDU.STU.GL]Sciences of the Universe [physics]/Earth Sciences/Glaciology; Antarctic; Byrd; Byrd Glacier; East Antarctica; Vostok Station; Antarc*; Antarctica; Antarctique*; ice core; Ice Sheet; Ice Shelf
• Online Access: https://theses.hal.science/tel-00693923; https://theses.hal.science/tel-00693923/document; https://theses.hal.science/tel-00693923/file/These-Ritz-1992.pdf

A model of ice flow with coupled velocity-temperature fields and ice-sheet reactions to climatic change is developed and applied to the flow line "Ridge B - Vostok - Byrd Glacier" (East Antarctica). The main processes to be taken into account, the basic equations and a bibliography study are presented in chapter (1). First a tool to interpret ice cores is developed in chapter (II). Velocities are derived from the ice sheet geometry and from accumulation rate. With this velocity field, the temperature field is obtained by solving the time dependent heat equation. The boundary conditions take into account possible melting at the ice base and the temperature distribution in the underlying bedrock. In chapter (III) this tool is used to compute the age of Vostok ice core. It is shown that the main uncertainty on this chronology is due to the poor knowledge of the accumulation rate upstream from Vostok station. Interpretation of the temperature profile measured in the Vostok borehole is also performed, providing information on the geothermal flux and the accumulation rate. The thermal-mechanical model (chapter IV) simulates ice thickness evolution with time. Ice velocity are numerically integrated and coupled with temperature at each time step. An iceshelf model is also developed and grounding line advance and retreat are computed depending on ice sheet and ice shelf dynamics. Sensitivity studies are performed for various model parameters. Variations in Vostok elevation during the last climatic cycle are presented and do not exceed 100 m. Un modèle d'écoulement de la glace est développé en tenant compte du couplage vitesse-température. Ce modèle permet l'étude des réactions d'une calotte polaire aux variations du climat et est appliqués à la ligne de courant "Ridge B - Vostok - Glacier Byrd". (Antarctique de l'Est). Les processus à prendre en compte, les équations de base ainsi qu'une étude bibliographique sont présentés au chapitre (1). Au chapitre (II) dans le but d'interpréter les forages glaciaires, nous ...