Articles | Volume 7, issue 4
The Cryosphere, 7, 1185–1192, 2013
The Cryosphere, 7, 1185–1192, 2013

Research article 26 Jul 2013

Research article | 26 Jul 2013

Influence of ice-sheet geometry and supraglacial lakes on seasonal ice-flow variability

I. Joughin1, S. B. Das2, G. E. Flowers3, M. D. Behn2, R. B. Alley4, M. A. King5,6, B. E. Smith1, J. L. Bamber7, M. R. van den Broeke8, and J. H. van Angelen8 I. Joughin et al.
  • 1Polar Science Center, Applied Physics Lab, University of Washington, 1013 NE 40th St., Seattle, WA 98105-6698, USA
  • 2Department of Geology and Geophysics, Woods Hole Oceanographic Institute, Woods Hole, MA 02543, USA
  • 3Department of Earth Sciences, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia, V5A 1S6, Canada
  • 4Department of Geosciences, and Earth and Environmental Systems Institute, Pennsylvania State University, University Park, PA 16802, USA
  • 5School of Geography and Environmental Studies, University of Tasmania, Private Bag 76, Hobart, Tasmania, 7001, Australia
  • 6School of Civil Engineering and Geoscience, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK
  • 7Bristol Glaciology Centre, School of Geographical Sciences, University of Bristol, University Road, Bristol, BS8 1SS, UK
  • 8Institute for Marine and Atmospheric Research, Utrecht University, 3584 CC Utrecht, the Netherlands

Abstract. Supraglacial lakes play an important role in establishing hydrological connections that allow lubricating seasonal meltwater to reach the base of the Greenland Ice Sheet. Here we use new surface velocity observations to examine the influence of supraglacial lake drainages and surface melt rate on ice flow. We find large, spatially extensive speedups concurrent with times of lake drainage, showing that lakes play a key role in modulating regional ice flow. While surface meltwater is supplied to the bed via a geographically sparse network of moulins, the observed ice-flow enhancement suggests that this meltwater spreads widely over the ice-sheet bed. We also find that the complex spatial pattern of speedup is strongly determined by the combined influence of bed and surface topography on subglacial water flow. Thus, modeling of ice-sheet basal hydrology likely will require knowledge of bed topography resolved at scales (sub-kilometer) far finer than existing data (several km).