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Un modèle thermo-mécanique d'évolution pour le bassin glaciaire Antarctique Vostok-Glacier Byrd : Sensibilité aux valeurs des paramètres mal connus.

Abstract : 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.
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https://tel.archives-ouvertes.fr/tel-00693923
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Submitted on : Thursday, May 3, 2012 - 10:04:53 AM
Last modification on : Friday, March 25, 2022 - 11:10:23 AM
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Catherine Ritz. Un modèle thermo-mécanique d'évolution pour le bassin glaciaire Antarctique Vostok-Glacier Byrd : Sensibilité aux valeurs des paramètres mal connus.. Glaciologie. Université Joseph-Fourier - Grenoble I, 1992. Français. ⟨tel-00693923⟩

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