Influence of a non-uniform velocity field on isochrone geometry along a steady flowline of an ice sheet

• Published in: Journal of Glaciology
• Main Authors: Parrenin, Frédéric, Hindmarsh, Richard
• 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), British Antarctic Survey (BAS), Natural Environment Research Council (NERC), ANR-05-BLAN-0165,MIDIGA,Modelling and Identification for Drillings Interpretation in Greenland and Antarctica(Modélisation et Identification pour l'Interprététation des Forages Antarctique et Groenland)(2005)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2007
• Subjects: [SDU.STU.GL]Sciences of the Universe [physics]/Earth Sciences/Glaciology; Weertman; Ice Sheet; Journal of Glaciology
• Online Access: https://hal-insu.archives-ouvertes.fr/insu-00377229; https://hal-insu.archives-ouvertes.fr/insu-00377229/document; https://hal-insu.archives-ouvertes.fr/insu-00377229/file/influence-of-a-non-uniform-velocity-field-on-isochrone-geometry-along-a-steady-flowline-of-an-ice-sheet.pdf; https://doi.org/10.3189/002214307784409298

International audience The relationship between velocity field and isochrone geometry along a steady flowline of an ice sheet is examined. The method is analytical and based upon the stream function and its vertically normalized form, the normalized stream function (NSF). We show that the slope of the isochrones is the slope of the iso-NSF lines, plus a path term which is the cumulative result of the past trajectory of the ice particles. We illustrate this path term in three different examples: varying basal melting, varying basal sliding (Weertman effect) and varying velocity profile around a divide (Raymond effect). The path term generally counteracts the slope of the iso-NSF lines. In the case of the Raymond effect, it can even lead to depressions surrounding the bumps if the transition from dome to flank velocity profile is sufficiently abrupt.