Influence of damage and basal friction on the grounding line dynamics
The Antartic ice sheet represents the world's largest potential contributor to sea level rise. Over 80 % of Antarctica's grounded ice drains through its fringing ice shelves which surround close to 45 % of the continent's shore. Because of Archimède' principle, the contribution o...
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ftunivnantes:oai:HAL:tel-01730867v1 2023-05-15T13:49:12+02:00 Influence of damage and basal friction on the grounding line dynamics Influence de l'endommagement et du frottement basal sur la dynamique de la ligne d'échouage Brondex, Julien 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 Olivier Gagliardini Fabien Gillet-Chaulet 2017-12-05 https://theses.hal.science/tel-01730867 https://theses.hal.science/tel-01730867/document https://theses.hal.science/tel-01730867/file/BRONDEX_2017_archivage.pdf fr fre HAL CCSD NNT: 2017GREAI092 tel-01730867 https://theses.hal.science/tel-01730867 https://theses.hal.science/tel-01730867/document https://theses.hal.science/tel-01730867/file/BRONDEX_2017_archivage.pdf info:eu-repo/semantics/OpenAccess https://theses.hal.science/tel-01730867 Sciences de la Terre. Université Grenoble Alpes, 2017. Français. ⟨NNT : 2017GREAI092⟩ Grounding line Damage Basal friction Modelling Finite element method Ligne d'échouage Endommagement Frottement basal Modélisation Méthode des éléments finis [SDU.STU]Sciences of the Universe [physics]/Earth Sciences info:eu-repo/semantics/doctoralThesis Theses 2017 ftunivnantes 2023-03-08T06:22:34Z The Antartic ice sheet represents the world's largest potential contributor to sea level rise. Over 80 % of Antarctica's grounded ice drains through its fringing ice shelves which surround close to 45 % of the continent's shore. Because of Archimède' principle, the contribution of the ice to sea level is accounted for as soon as it flows through the grounding line, which defines the limit beyond which ice grounded on the bedrock starts floating on the ocean. Therefore, realistic modelling of grounding line dynamics is crucial to produce trustworthy projections of future sea level rise. This dynamics is affected by a number of physical processes, some of which are not properly represented in current ice flow models. This PhD thesis focuses on two of these processes: damage of ice on the one hand and basal friction related to basal hydrology on the other hand.Damage accounts for the degradation of ice mechanical properties due to the presence of fractures and crevasses, commonly observed at the surface of glaciers. Damage affects ice flow by lowering ice viscosity. The evolution of damage is governed by a pure advection equation, the numerical resolution of which requires stabilisation methods. We show that, for numerical resolutions associated to acceptable calculation times, grounding line dynamics is sensitive to the choice of this method, which seriously complicates the modelling of damage processes.Ice flow models account for basal friction through the use of friction laws, i.e. the mathematical relationship between basal drag and sliding velocities. Several formulations of these laws have been proposed over the last decades based on theoretical arguments. Some of these formulations explicitly include the effect of basal water which is present in the subglacial drainage system and the pressure of which eases basal motion. Unfortunately, the temporal and spatial scales at stake in glaciology make it impossible to validate these different formulations in situ and large-scale ice flow models usually make use of ... Doctoral or Postdoctoral Thesis Antarc* antartic* Ice Sheet Ice Shelves Université de Nantes: HAL-UNIV-NANTES |
institution |
Open Polar |
collection |
Université de Nantes: HAL-UNIV-NANTES |
op_collection_id |
ftunivnantes |
language |
French |
topic |
Grounding line Damage Basal friction Modelling Finite element method Ligne d'échouage Endommagement Frottement basal Modélisation Méthode des éléments finis [SDU.STU]Sciences of the Universe [physics]/Earth Sciences |
spellingShingle |
Grounding line Damage Basal friction Modelling Finite element method Ligne d'échouage Endommagement Frottement basal Modélisation Méthode des éléments finis [SDU.STU]Sciences of the Universe [physics]/Earth Sciences Brondex, Julien Influence of damage and basal friction on the grounding line dynamics |
topic_facet |
Grounding line Damage Basal friction Modelling Finite element method Ligne d'échouage Endommagement Frottement basal Modélisation Méthode des éléments finis [SDU.STU]Sciences of the Universe [physics]/Earth Sciences |
description |
The Antartic ice sheet represents the world's largest potential contributor to sea level rise. Over 80 % of Antarctica's grounded ice drains through its fringing ice shelves which surround close to 45 % of the continent's shore. Because of Archimède' principle, the contribution of the ice to sea level is accounted for as soon as it flows through the grounding line, which defines the limit beyond which ice grounded on the bedrock starts floating on the ocean. Therefore, realistic modelling of grounding line dynamics is crucial to produce trustworthy projections of future sea level rise. This dynamics is affected by a number of physical processes, some of which are not properly represented in current ice flow models. This PhD thesis focuses on two of these processes: damage of ice on the one hand and basal friction related to basal hydrology on the other hand.Damage accounts for the degradation of ice mechanical properties due to the presence of fractures and crevasses, commonly observed at the surface of glaciers. Damage affects ice flow by lowering ice viscosity. The evolution of damage is governed by a pure advection equation, the numerical resolution of which requires stabilisation methods. We show that, for numerical resolutions associated to acceptable calculation times, grounding line dynamics is sensitive to the choice of this method, which seriously complicates the modelling of damage processes.Ice flow models account for basal friction through the use of friction laws, i.e. the mathematical relationship between basal drag and sliding velocities. Several formulations of these laws have been proposed over the last decades based on theoretical arguments. Some of these formulations explicitly include the effect of basal water which is present in the subglacial drainage system and the pressure of which eases basal motion. Unfortunately, the temporal and spatial scales at stake in glaciology make it impossible to validate these different formulations in situ and large-scale ice flow models usually make use of ... |
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 Olivier Gagliardini Fabien Gillet-Chaulet |
format |
Doctoral or Postdoctoral Thesis |
author |
Brondex, Julien |
author_facet |
Brondex, Julien |
author_sort |
Brondex, Julien |
title |
Influence of damage and basal friction on the grounding line dynamics |
title_short |
Influence of damage and basal friction on the grounding line dynamics |
title_full |
Influence of damage and basal friction on the grounding line dynamics |
title_fullStr |
Influence of damage and basal friction on the grounding line dynamics |
title_full_unstemmed |
Influence of damage and basal friction on the grounding line dynamics |
title_sort |
influence of damage and basal friction on the grounding line dynamics |
publisher |
HAL CCSD |
publishDate |
2017 |
url |
https://theses.hal.science/tel-01730867 https://theses.hal.science/tel-01730867/document https://theses.hal.science/tel-01730867/file/BRONDEX_2017_archivage.pdf |
genre |
Antarc* antartic* Ice Sheet Ice Shelves |
genre_facet |
Antarc* antartic* Ice Sheet Ice Shelves |
op_source |
https://theses.hal.science/tel-01730867 Sciences de la Terre. Université Grenoble Alpes, 2017. Français. ⟨NNT : 2017GREAI092⟩ |
op_relation |
NNT: 2017GREAI092 tel-01730867 https://theses.hal.science/tel-01730867 https://theses.hal.science/tel-01730867/document https://theses.hal.science/tel-01730867/file/BRONDEX_2017_archivage.pdf |
op_rights |
info:eu-repo/semantics/OpenAccess |
_version_ |
1766250998708305920 |