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Seasonal speedup of a Greenland marine-terminating outlet glacier forced by surface melt-induced changes in subglacial hydrology

Lookup NU author(s): Professor Matt King


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We present subdaily ice flow measurements at four GPS sites between 36 and 72 km from the margin of a marine-terminating Greenland outlet glacier spanning the 2009 melt season. Our data show that >35 km from the margin, seasonal and shorter-time scale ice flow variations are controlled by surface melt-induced changes in subglacial hydrology. Following the onset of melting at each site, ice motion increased above background for up to 2 months with resultant up-glacier migration of both the onset and peak of acceleration. Later in our survey, ice flow at all sites decreased to below background. Multiple 1 to 15 day speedups increased ice motion by up to 40% above background. These events were typically accompanied by uplift and coincided with enhanced surface melt or lake drainage. Our results indicate that the subglacial drainage system evolved through the season with efficient drainage extending to at least 48 km inland during the melt season. While we can explain our observations with reference to evolution of the glacier drainage system, the net effect of the summer speed variations on annual motion is small (similar to 1%). This, in part, is because the speedups are compensated for by slowdowns beneath background associated with the establishment of an efficient subglacial drainage system. In addition, the speedups are less pronounced in comparison to land-terminating systems. Our results reveal similarities between the inland ice flow response of Greenland marine- and land-terminating outlet glaciers.

Publication metadata

Author(s): Sole AJ, Mair DWF, Nienow PW, Bartholomew ID, King MA, Burke MJ, Joughin I

Publication type: Article

Publication status: Published

Journal: Journal of Geophysical Research: Earth Surface

Year: 2011

Volume: 116

Issue: F3

Print publication date: 01/08/2011

ISSN (print): 0148-0227

ISSN (electronic): 2156–2202

Publisher: American Geophysical Union


DOI: 10.1029/2010JF001948


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