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

A. J. Sole, D. W. F. Mair, P. W. Nienow, I. D. Bartholomew, M. A. King, M. J. Burke, I. Joughin

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Abstract

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 (~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.
Original languageEnglish
Article numberF03014
Number of pages11
JournalJournal of Geophysical Research: Earth Surface
Volume116
Issue numberF3
Early online date23 Aug 2011
DOIs
Publication statusPublished - Sep 2011

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Glaciers
hydrology
glaciers
Greenland
Hydrology
ice flow
Ice
outlets
stopping
drainage
glacier
ice
Drainage
melt
drainage systems
margins
flow measurement
GPS
melting
uplift

Keywords

  • glacier
  • hydrology
  • Greenland Ice Sheet
  • tidewater glacier
  • surface meltwater
  • Greenland
  • dynamics
  • outlet glacier
  • tidewater

Cite this

Seasonal speedup of a Greenland marine-terminating outlet glacier forced by surface melt-induced changes in subglacial hydrology. / Sole, A. J.; Mair, D. W. F. ; Nienow, P. W.; Bartholomew, I. D. ; King, M. A.; Burke, M. J. ; Joughin, I.

In: Journal of Geophysical Research: Earth Surface, Vol. 116, No. F3, F03014, 09.2011.

Research output: Contribution to journalArticle

Sole, A. J. ; Mair, D. W. F. ; Nienow, P. W. ; Bartholomew, I. D. ; King, M. A. ; Burke, M. J. ; Joughin, I. / Seasonal speedup of a Greenland marine-terminating outlet glacier forced by surface melt-induced changes in subglacial hydrology. In: Journal of Geophysical Research: Earth Surface. 2011 ; Vol. 116, No. F3.
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