Atmospheric variability in West Antarctica : impact on the ocean circulation and on theice-sheet surface mass balance
West Antarctica, and particularly the Amundsen sector, has shown since the 1990s a large increase of mass loss related to coastal glacier acceleration in response to an increase of oceanic melt underneath ice shelves. Ice shelves play a buttressing role for ice-stream and increased oceanic melt ther...
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Online Access: | https://theses.hal.science/tel-02475556 https://theses.hal.science/tel-02475556/document https://theses.hal.science/tel-02475556/file/DONAT-MAGNIN_2019_diffusion.pdf |
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ftunigrenoble:oai:HAL:tel-02475556v1 2024-05-12T07:53:42+00:00 Atmospheric variability in West Antarctica : impact on the ocean circulation and on theice-sheet surface mass balance Variabilité atmosphérique en Antarctique de l'Ouest : Impact sur la circulation océanique et sur le bilan de masse de surface de la calotte Donat-Magnin, Marion 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 Hubert Gallée Nicolas Jourdain 2019-11-14 https://theses.hal.science/tel-02475556 https://theses.hal.science/tel-02475556/document https://theses.hal.science/tel-02475556/file/DONAT-MAGNIN_2019_diffusion.pdf en eng HAL CCSD NNT: 2019GREAU032 tel-02475556 https://theses.hal.science/tel-02475556 https://theses.hal.science/tel-02475556/document https://theses.hal.science/tel-02475556/file/DONAT-MAGNIN_2019_diffusion.pdf info:eu-repo/semantics/OpenAccess https://theses.hal.science/tel-02475556 Ocean, Atmosphere. Université Grenoble Alpes, 2019. English. ⟨NNT : 2019GREAU032⟩ Climate variability Southern Ocean Antarctic surface mass balance Climate projections Regional modelisation Amundsen Modélisation atmosphérique régionale Océan Austral Bilan de masse de surface Projections climatiques Variabilité interannuelle et décennale [SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere info:eu-repo/semantics/doctoralThesis Theses 2019 ftunigrenoble 2024-04-18T03:37:33Z West Antarctica, and particularly the Amundsen sector, has shown since the 1990s a large increase of mass loss related to coastal glacier acceleration in response to an increase of oceanic melt underneath ice shelves. Ice shelves play a buttressing role for ice-stream and increased oceanic melt therefore lead to ice shelves thinning and glacier acceleration, which contributes to sea level rise. West Antarctica is of particular concern because its configuration is prone to marine ice-sheet instability. It has been suggested that ice shelves weaken under large surface melt in a warmer climate (hydrofracturing), possibly leading to another kind of instability. Instabilities could be slowed down or compensated by future Surface Mass Balance (SMB) that consists mainly of snowfall, sporadic rainfall, and is slightly reduced by sublimation and runoff. The main objective of this PhD work is to model the atmospheric and oceanic processes that will most likely affect the future West Antarctic contribution to sea level rise.First, oceanic projections have been developed using the NEMO ocean model. The ocean circulation induced by ice-shelf basal melting affects the ocean response to future changes in surface winds. Therefore, models that do not represent ice-shelf cavities produce wrong warming patterns around Antarctica. A positive feedback between oceanic melting and grounding-line retreat has been identified and can increase melt rates by a factor of 2.5. These results are strong incentive to couple ocean and ice sheet models, although the projections proposed here are relatively idealized.To run SMB and surface melting projections, an atmospheric model with a fine representation of polar processes, including those related to the snowpack, is needed. MAR is found to be an appropriate tool to simulate the present-day surface climate in the Amundsen region. We find that none of the large climate modes of variability (ASL, SAM, ENSO) explains more than 50% of surface melt and SMB summer variance at the interannual ... Doctoral or Postdoctoral Thesis Antarc* Antarctic Antarctica Antarctique* Ice Sheet Ice Shelf Ice Shelves Southern Ocean West Antarctica Université Grenoble Alpes: HAL Antarctic Austral Southern Ocean West Antarctica |
institution |
Open Polar |
collection |
Université Grenoble Alpes: HAL |
op_collection_id |
ftunigrenoble |
language |
English |
topic |
Climate variability Southern Ocean Antarctic surface mass balance Climate projections Regional modelisation Amundsen Modélisation atmosphérique régionale Océan Austral Bilan de masse de surface Projections climatiques Variabilité interannuelle et décennale [SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere |
spellingShingle |
Climate variability Southern Ocean Antarctic surface mass balance Climate projections Regional modelisation Amundsen Modélisation atmosphérique régionale Océan Austral Bilan de masse de surface Projections climatiques Variabilité interannuelle et décennale [SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere Donat-Magnin, Marion Atmospheric variability in West Antarctica : impact on the ocean circulation and on theice-sheet surface mass balance |
topic_facet |
Climate variability Southern Ocean Antarctic surface mass balance Climate projections Regional modelisation Amundsen Modélisation atmosphérique régionale Océan Austral Bilan de masse de surface Projections climatiques Variabilité interannuelle et décennale [SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere |
description |
West Antarctica, and particularly the Amundsen sector, has shown since the 1990s a large increase of mass loss related to coastal glacier acceleration in response to an increase of oceanic melt underneath ice shelves. Ice shelves play a buttressing role for ice-stream and increased oceanic melt therefore lead to ice shelves thinning and glacier acceleration, which contributes to sea level rise. West Antarctica is of particular concern because its configuration is prone to marine ice-sheet instability. It has been suggested that ice shelves weaken under large surface melt in a warmer climate (hydrofracturing), possibly leading to another kind of instability. Instabilities could be slowed down or compensated by future Surface Mass Balance (SMB) that consists mainly of snowfall, sporadic rainfall, and is slightly reduced by sublimation and runoff. The main objective of this PhD work is to model the atmospheric and oceanic processes that will most likely affect the future West Antarctic contribution to sea level rise.First, oceanic projections have been developed using the NEMO ocean model. The ocean circulation induced by ice-shelf basal melting affects the ocean response to future changes in surface winds. Therefore, models that do not represent ice-shelf cavities produce wrong warming patterns around Antarctica. A positive feedback between oceanic melting and grounding-line retreat has been identified and can increase melt rates by a factor of 2.5. These results are strong incentive to couple ocean and ice sheet models, although the projections proposed here are relatively idealized.To run SMB and surface melting projections, an atmospheric model with a fine representation of polar processes, including those related to the snowpack, is needed. MAR is found to be an appropriate tool to simulate the present-day surface climate in the Amundsen region. We find that none of the large climate modes of variability (ASL, SAM, ENSO) explains more than 50% of surface melt and SMB summer variance at the interannual ... |
author2 |
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 Hubert Gallée Nicolas Jourdain |
format |
Doctoral or Postdoctoral Thesis |
author |
Donat-Magnin, Marion |
author_facet |
Donat-Magnin, Marion |
author_sort |
Donat-Magnin, Marion |
title |
Atmospheric variability in West Antarctica : impact on the ocean circulation and on theice-sheet surface mass balance |
title_short |
Atmospheric variability in West Antarctica : impact on the ocean circulation and on theice-sheet surface mass balance |
title_full |
Atmospheric variability in West Antarctica : impact on the ocean circulation and on theice-sheet surface mass balance |
title_fullStr |
Atmospheric variability in West Antarctica : impact on the ocean circulation and on theice-sheet surface mass balance |
title_full_unstemmed |
Atmospheric variability in West Antarctica : impact on the ocean circulation and on theice-sheet surface mass balance |
title_sort |
atmospheric variability in west antarctica : impact on the ocean circulation and on theice-sheet surface mass balance |
publisher |
HAL CCSD |
publishDate |
2019 |
url |
https://theses.hal.science/tel-02475556 https://theses.hal.science/tel-02475556/document https://theses.hal.science/tel-02475556/file/DONAT-MAGNIN_2019_diffusion.pdf |
geographic |
Antarctic Austral Southern Ocean West Antarctica |
geographic_facet |
Antarctic Austral Southern Ocean West Antarctica |
genre |
Antarc* Antarctic Antarctica Antarctique* Ice Sheet Ice Shelf Ice Shelves Southern Ocean West Antarctica |
genre_facet |
Antarc* Antarctic Antarctica Antarctique* Ice Sheet Ice Shelf Ice Shelves Southern Ocean West Antarctica |
op_source |
https://theses.hal.science/tel-02475556 Ocean, Atmosphere. Université Grenoble Alpes, 2019. English. ⟨NNT : 2019GREAU032⟩ |
op_relation |
NNT: 2019GREAU032 tel-02475556 https://theses.hal.science/tel-02475556 https://theses.hal.science/tel-02475556/document https://theses.hal.science/tel-02475556/file/DONAT-MAGNIN_2019_diffusion.pdf |
op_rights |
info:eu-repo/semantics/OpenAccess |
_version_ |
1798844180350369792 |