Trois problèmes inverses en glaciologie

• Main Author: Rommelaere, Vincent
• 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, Catherine Ritz
• Format: Doctoral or Postdoctoral Thesis
• Language: French
• Published: HAL CCSD 1997
• Subjects: Problèmes inverses; glaciologie; Vostok; paléothermométrie; transport gaz; névé; glace; atmosphère du passé; transfert air- névé- glace; CFC; Ross Ice Shelf; rhéologie; [SDU.STU.GL]Sciences of the Universe [physics]/Earth Sciences/Glaciology; Antarc*; Antarctic; Antarctica; Ice Sheet; Ice Shelf; Ice Shelves
• Online Access: https://theses.hal.science/tel-00701278; https://theses.hal.science/tel-00701278/document; https://theses.hal.science/tel-00701278/file/Rommelaere-these-1997.pdf

Many questions of glaciological interest can be recognized as inverse problems. In this thesis, l illustrate this point through three examples: * Reconstruction of past temperatures : l try to combine the information given by ice isotopic composition and measured temperature profile at Vostok (Antarctica). This approach suggests that the temperature profile is not able to give any better estimate of surface temperature during the last glacial period than the classical isotopic thermometer (at Vostok). * Reconstruction of past atmospheres : air composition measured in bubbles of ice cores gives tremendous information about past atmospheres. However, the interpretation of these measurements is not immediate, because some natural phenomena can alter the composition of bubble air. l propose here a method to extract the atmospheric signal of ice cores, taking firn diffusion and gravitational separation into account. This method is then applied to interpret methane, CFCs and Û 13 C of CH, measurements. * Reconstruction of large-scale rheological properties of ice: ice-shelves and ice-streams are dynamic elements of the Antarctic ice sheet. Their rheology is an important parameter to predict the evolution of the Antarctic ice sheet. l present here a possible means to determine the effective viscosity of an ice-shelf using an ice-shelf flow model and velocity and thickness measurements. The results consist of a map of the effective viscosity of the Ross Ice Shelf. Inverse methods used to treat these problems are weIl known in many fields of geophysical sciences, but they have been used occasionaIly in glaciology. l try to show what can be learnt from their application in glaciology, but also their limits. Les questions que se pose le glaciologue peuvent souvent être identifiées à des problèmes inverses. C'est ce qui est illustré dans ce travail à travers trois exemples: * Reconstruction des températures du passé : nous essayons de combiner l'information donnée par la composition isotopique de la glace et le profil de ...