Rifting and calving processes of Antarctica icebergs : Story of the Mertz Glacier

• Main Author: Lescarmontier, Lydie
• Other Authors: Cryosphère satelittaire (CRYO), Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France-Centre National de la Recherche Scientifique (CNRS), Université Paul Sabatier - Toulouse III, Benoît LEGRESY et Richard COLEMAN
• Format: Doctoral or Postdoctoral Thesis
• Language: French
• Published: HAL CCSD 2012
• Subjects: Antarctica Glacier; Iceberg calving; Ocean-Ice interaction; GPS processing; Glacier émissaire; Antarctique; Iceberg; Vêlage; Fracturation; Interaction océan-glace; Traitement GPS; [SDU.OCEAN]Sciences of the Universe [physics]/Ocean; Atmosphere; East Antarctica; Mertz Glacier; George V Land; Antarc*; Antarctica; Antarctique*
• Online Access: https://theses.hal.science/tel-00730943; https://theses.hal.science/tel-00730943/document; https://theses.hal.science/tel-00730943/file/thesis_Lescarmontier.pdf

This thesis presents a study of the rifting processes of an outflow glacier leading to cal- ving. In the context of the CRAC-ICE program we worked on understanding the evolution of the Mertz Glacier, located in the King George V Land, East Antarctica. Before its cal- ving which occurred in February 2010, releasing an iceberg of about 80 km long and 35 km width, the Mertz Glacier was characterized by an ice tongue extending into the open ocean. This ice tongue, fractured by a large rift since the beginning of 1990, was 150 km long by 35 km in width. Using a range of in-situ GPS data, satellite images and an ocea- nic tide model (TUGO-Mertz), we followed the evolution of the glacier and the calving of its iceberg. The first part of this study consisted in developing a high precision GPS processing strategy allowing us to get the best accuracy possible for our measurements. These data were processed using the GINS software and a processing strategy named IPPP, based on absolute positioning. The accuracy of our results allowed us the ability to observe centimeter scale oscillations of the ice tongue. Then, we compared these observed signals with an Euler-Bernoulli beam based model, and found out that they matched with vibration modes of the ice tongue in three different configurations. The periods recorded varied from 5 minutes to a few hours. In this range of temporal values, the main oceanic forcing mechanisms are ocean swell and infra-gravity waves. We also demonstrated that the vibrations of the glacier tongue, lead to torsion movements and hence rifting. At larger spatial scale, tidal currents and ocean sea surface height impacts on the evolution of the ice tongue. Tidal currents mainly affect the rift opening, whereas the sea surface height tends to modulate the along flow current velocity. In addition to these mechanisms, we followed the evolution of the main rift, first opening on the eastern part of the ice tongue and then on the western part until the glacier calved. Finally, we focused on the different ...