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    Relationship between Greenland Ice Sheet surface speed and modeled effective pressure

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    Article (3.772Mb)
    Supporting Information S1 (13.19Mb)
    Date
    2018-09-27
    Author
    Stevens, Laura A.  Concept link
    Hewitt, Ian J.  Concept link
    Das, Sarah B.  Concept link
    Behn, Mark D.  Concept link
    Metadata
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    Citable URI
    https://hdl.handle.net/1912/10666
    As published
    https://doi.org/10.1029/2017JF004581
    DOI
    10.1029/2017JF004581
    Keyword
     Glaciology; Greenland; Subglacial hydrology; Numerical modeling; Ice dynamics 
    Abstract
    We use a numerical subglacial hydrology model and remotely sensed observations of Greenland Ice Sheet surface motion to test whether the inverse relationship between effective pressure and regional melt season surface speeds observed at individual sites holds on a regional scale. The model is forced with daily surface runoff estimates for 2009 and 2010 across an ~8,000‐km2 region on the western margin. The overall subglacial drainage system morphology develops similarly in both years, with subglacial channel networks growing inland from the ice sheet margin and robust subglacial pathways forming over bedrock ridges. Modeled effective pressures are compared to contemporaneous regional surface speeds derived from TerraSAR‐X imagery to investigate spatial relationships. Our results show an inverse spatial relationship between effective pressure and ice speed in the mid‐melt season, when surface speeds are elevated, indicating that effective pressure is the dominant control on surface velocities in the mid‐melt season. By contrast, in the early and late melt seasons, when surface speeds are slower, effective pressure and surface speed have a positive relationship. Our results suggest that outside of the mid‐melt season, the influence of effective pressures on sliding speeds may be secondary to the influence of driving stress and spatially variable bed roughness.
    Description
    Author Posting. © American Geophysical Union, 2018. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Earth Surface 123 (2018): 2258-2278, doi:10.1029/2017JF004581.
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    • Geology and Geophysics (G&G)
    Suggested Citation
    Journal of Geophysical Research: Earth Surface 123 (2018): 2258-2278
     

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