Marine ice sheet dynamics: Hysteresis and neutral equilibrium

• Published in: Journal of Geophysical Research
• Main Authors: Durand, Gaël, Gagliardini, Olivier, de Fleurian, B., Zwinger, T., Le Meur, Emmanuel
• 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), Scientific Computing Ltd (CSC), ANR-06-VULN-0016,DACOTA,Dynamique des glaciers côtiers et rôle sur le bilan de masse global de l'Antarctique zone atelier du glacier de l'Astrolabe, Terre Adélie(2006)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2009
• Subjects: marine ice sheet; grounding line; full Stokes modeling; [SDU.STU.GL]Sciences of the Universe [physics]/Earth Sciences/Glaciology; Ice Sheet; Sea ice
• Online Access: https://hal-insu.archives-ouvertes.fr/insu-00420410; https://hal-insu.archives-ouvertes.fr/insu-00420410/document; https://hal-insu.archives-ouvertes.fr/insu-00420410/file/2008JF001170.pdf; https://doi.org/10.1029/2008JF001170

International audience The stability of marine ice sheets and outlet glaciers is mostly controlled by the dynamics of their grounding line, i.e., where the bottom contact of the ice changes from bedrock or till to ocean water. The last report of the Intergovernmental Panel on Climate Change has clearly underlined the poor ability of models to capture the dynamics of outlet glaciers. Here we present computations of grounding line dynamics on the basis of numerical solutions of the full Stokes equations for ice velocity, coupled with the evolution of the air ice– and sea ice–free interfaces. The grounding line position is determined by solving the contact problem between the ice and a rigid bedrock using the finite element code Elmer. Results of the simulations show that marine ice sheets are unstable on upsloping beds and undergo hysteresis under perturbation of ice viscosity, confirming conclusions from boundary layer theory. The present approach also indicates that a 2-D unconfined marine ice sheet sliding over a downsloping bedrock does not exhibit neutral equilibrium. It is shown that mesh resolution around the grounding line is a crucial issue. A very fine grid size (<100 m spacing) is needed in order to achieve consistent results.