Towards a new modeling framework for sea ice mechanics

• Main Author: Girard, Lucas
• 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), Université Joseph-Fourier - Grenoble I, Jerome Weiss([e-mail])
• Format: Doctoral or Postdoctoral Thesis
• Language: French
• Published: HAL CCSD 2010
• Subjects: sea ice; rheology; dynamics; fracture; spatial and temporal scaling; glace de mer; banquise; rhéologie; rupture; loi d'échelle spatiale et temporelle; [SPI.MECA]Engineering Sciences [physics]/Mechanics [physics.med-ph]; [SDU.OCEAN]Sciences of the Universe [physics]/Ocean; Atmosphere; Sea ice
• Online Access: https://theses.hal.science/tel-00561893; https://theses.hal.science/tel-00561893/document; https://theses.hal.science/tel-00561893/file/2010-10-05_phd_lucas_printversion.pdf

In this thesis, new approaches are used to model the mechanical behavior of sea ice and to evaluate sea ice models in terms of ice drift and deformation. It is first shown how the statistical and scaling properties of sea ice drift and deformation can be used as an evaluation metric for sea ice models. These properties are known to play an important role regarding ice growth estimates and should therefore be captured in sea ice models. The evaluation metric is applied to simulations performed with a coupled ocean/sea ice model, where the mechanical behavior of sea ice is represented using the Viscous-Plastic (VP) rheology, as in most current global ocean and climate models. The VP model is shown to be unable to capture the statistical and scaling properties of sea ice deformation. As these properties are a signature of the ice mechanical behavior, it suggests that the VP rheology is inappropriate for sea ice modeling. The new mechanical model developped during this thesis is based on the hyopthesis that sea ice deformation is mainly accommodated by fracturing and frictional sliding (brittle behavior) over a wide range of scales (stresses can be transmitted on long distances). The main characteristics of this new model, named the Elasto-Brittle (EB) rheology, are progressive damage to represent the brittle behavior, and an elastic constitutive law to allow long-range elastic interactions to take place. The EB rheology is first used to carry out a fundamental study of fracture in heterogeneous media. Simulations show that fracture is preceded by a divergence of the correlation length, measured from a correlation analysis of discrete events and from a scaling analysis of the continuous strain-rate field. The scaling properties of deformation that emerge in the vicinity of failure ressemble those observed for the brittle deformation of geophysical objects such as sea ice or the earth's crust. These results, that argue for a critical point interpretation of fracture, are discussed in the context of fracture at ...