Recent mechanical weakening of the Arctic sea ice cover as revealed from larger inertial oscillations

• Published in: Journal of Geophysical Research: Oceans
• Main Authors: Gimbert, Florent, Jourdain, Nicolas C., Marsan, David, Weiss, Jérôme, Barnier, Bernard
• Other Authors: Mécanique des failles, Institut des Sciences de la Terre (ISTerre), Université Joseph Fourier - Grenoble 1 (UJF)-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Institut national des sciences de l'Univers (INSU - CNRS)-Institut de recherche pour le développement IRD : UR219-PRES Université de Grenoble-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 Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Institut national des sciences de l'Univers (INSU - CNRS)-Institut de recherche pour le développement IRD : UR219-PRES Université de Grenoble-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Écoulements Géophysiques et Industriels Grenoble (LEGI), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS), 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)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2012
• Subjects: analytical modelling; inertial oscillations; mechanical behavior; ocean surface layer; sea ice; [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph]; [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph]; [SDE.MCG]Environmental Sciences/Global Changes; [SDU.STU.GL]Sciences of the Universe [physics]/Earth Sciences/Glaciology; Arctic; Sea ice
• Online Access: https://hal.science/hal-00752410; https://hal.science/hal-00752410/document; https://hal.science/hal-00752410/file/2011JC007633.pdf; https://doi.org/10.1029/2011JC007633

International audience We present a simple and analytical ocean boundary layer-sea ice coupled dynamical model that we apply to the modeling of Arctic sea ice motion in the frequency domain, and particularly in the inertial range. This study further complements our related work in an unpublished paper where the sea ice cover response to the Coriolis forcing has been studied. This analytical model allows interpretation of the spatial, seasonal and pluriannual dependence of the magnitude of the inertial oscillations detailed in terms of mechanical behavior of the ice cover. In this model, the sea ice mechanical response is simplified through the introduction of a linear internal friction term K. A dependence of K allows us to explain the associated dependence of the seasonal and regional Arctic sea ice inertial motion. In addition, a significant decrease of K, i.e., a mechanical weakening of the sea ice cover, is observed for the period 2002-2008 compared to 1979-2001, for the entire Arctic in both seasons. These results show that the regional, seasonal and pluriannual variations of sea ice inertial motion are not only the trivial consequence of simultaneous variations of thickness and concentration (and so of ice mass per unit area). Instead, the shrinking and thinning of the Arctic sea ice cover over the last few decades has induced a mechanical weakening, which in turns has favored sea ice fracturing and deformation.