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

• Published in: The Cryosphere
• Main Authors: Joughin, Ian, Das, Sarah B., Flowers, G. E., Behn, Mark D., Alley, Richard B., King, Matt A., Smith, B. E., Bamber, Jonathan L., van den Broeke, Michiel R., van Angelen, J. H.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Copernicus Publications on behalf of the European Geosciences Union 2013
• Subjects: Behn; Canada; Greenland; Ice Sheet; The Cryosphere
• Online Access: https://hdl.handle.net/1912/6247

© The Author(s), 2013. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in The Cryosphere 7 (2013): 1185-1192, doi:10.5194/tc-7-1185-2013. 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). This work was supported jointly by National Science Foundation’s Office of Polar Programs (NSF-OPP) and National Aeronautics and Space Administration’s (NASA) Cryospheric Sciences Program (and through ARC-0520382, ARC-1023382 and NNX10AI33G to I. Joughin; and ARC-0520077, ARC-1023364 and NNX10AI30G to S. B. Das and M. D. Behn). The Natural Sciences and Engineering Research Council of Canada (NSERC) and the Canada Research Chairs Program (CRC) provided support for G. E. Flowers. Support for R. B. Alley was provided by NSF (ANT-0424589 and ARC- 0909335). Contributions by M. A. King were supported by NERC and an Australian Research Council Future Fellowship (project number FT110100207).