Recent climatic variability of Antarctica : contribution of the records from firn cores

• Main Author: Goursaud, Sentia
• Other Authors: Institut des Géosciences de l’Environnement (IGE), Institut de Recherche pour le Développement (IRD)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes 2016-2019 (UGA 2016-2019 ), Université Grenoble Alpes, Michel Legrand, Valérie Masson-Delmotte
• Format: Doctoral or Postdoctoral Thesis
• Language: French
• Published: HAL CCSD 2018
• Subjects: Climatic variability of Antarctica; Firn cores; Water stabe isotopes; Atmospheric general circulation model; Variabtilité climatique de l'Antarctique; Carottes de névé; Isotopes stables de l'eau; Modélisation atmosphérique de circulation générale; [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology; Antarctic; Antarc*; Antarctica; ice core
• Online Access: https://theses.hal.science/tel-01999086; https://theses.hal.science/tel-01999086/document; https://theses.hal.science/tel-01999086/file/GOURSAUD_2018_archivage.pdf

Documenting recent Antarctic climate variability is needed in order to understand the mechanisms at play, associated with the role of Antarctic mass balance for global sea level rise. Proxy records from Antarctic shallow firn cores are precious data, which complement instrumental and remote sensing observations to continuously cover the whole continent. Within these ice cores, water stable isotopes are commonly used to quantify past changes in local temperature.This PhD thesis was initiated within the French Agence Nationale de la Recherche “Improving the Accurancy of SUrface Mass balance of Antarctica” (ASUMA) project, which aims to reconstruct and to identify the processes controlling the spatio-temporal variability of the surface mass balance (SMB) in Adélie Land. I used water stable isotopes records from recently drilled shallow firn cores, as well as atmospheric simulations performed with the high resolution atmospheric general circulation model ECHAM5-wiso model, equipped with water stable isotopes, atmospheric reanalyses and back-trajectories, instrumental and remote sensing climate observations.In a first part, I assessed the skills of the ECHAM5-wiso with respect to Antarctic temperature, SMB, δ18O and deuterium excess (hereafter d-excess), as a prerequisite for the exploitation of the model to interpret isotope compositions. I developed Antarctic-wide diagnostics of the δ18O-temperature and d-excess- δ18O relationships, showing differences in the spatial, seasonal and interannual δ18O-temperature slopes. Within the international working group of PAGES (Past Global Changes) Antarctica 2k, I used the calibrations inferred from ECHAM5-wiso to reconstruct temperatures over 7 Antarctic regions from a synthesis of ice core δ18O records spanning the past 2,000 years.In a second part, new water stable isotope records from two firn core drilled in Adélie Land, the S1C1 and the TA192A, were investigated, covering the periods 1947-2007 and 1998-2014 respectively. The reconstructed SMB display a high spatial ...