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The Cryosphere An interactive open-access journal of the European Geosciences Union
The Cryosphere, 11, 451-467, 2017
http://www.the-cryosphere.net/11/451/2017/
doi:10.5194/tc-11-451-2017
© Author(s) 2017. This work is distributed
under the Creative Commons Attribution 3.0 License.
Research article
08 Feb 2017
Connected subglacial lake drainage beneath Thwaites Glacier, West Antarctica
Benjamin E. Smith1, Noel Gourmelen2,3, Alexander Huth4, and Ian Joughin1 1Applied Physics Lab, University of Washington, Seattle, WA 98195, USA
2School of Geosciences, University of Edinburgh, Edinburgh, EH8, Scotland
3IPGS UMR 7516, Université de Strasbourg, CNRS, Strasbourg, France
4Department of Earth and Space Sciences, University of Washington, Seattle, WA 98195, USA
Abstract. We present conventional and swath altimetry data from CryoSat-2, revealing a system of subglacial lakes that drained between June 2013 and January 2014 under the central part of Thwaites Glacier, West Antarctica (TWG). Much of the drainage happened in less than 6 months, with an apparent connection between three lakes spanning more than 130 km. Hydro-potential analysis of the glacier bed shows a large number of small closed basins that should trap water produced by subglacial melt, although the observed large-scale motion of water suggests that water can sometimes locally move against the apparent potential gradient, at least during lake-drainage events. This shows that there are important limitations in the ability of hydro-potential maps to predict subglacial water flow. An interpretation based on a map of the melt rate suggests that lake drainages of this type should take place every 20–80 years, depending on the connectivity of the water flow at the bed. Although we observed an acceleration in the downstream part of TWG immediately before the start of the lake drainage, there is no clear connection between the drainage and any speed change of the glacier.

Citation: Smith, B. E., Gourmelen, N., Huth, A., and Joughin, I.: Connected subglacial lake drainage beneath Thwaites Glacier, West Antarctica, The Cryosphere, 11, 451-467, doi:10.5194/tc-11-451-2017, 2017.
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Short summary
In this paper we investigate elevation changes of Thwaites Glacier, West Antarctica, one of the main sources of excess ice discharge into the ocean. We find that in early 2013, four subglacial lakes separated by 100 km drained suddenly, discharging more than 3 km3 of water under the fastest part of the glacier in less than 6 months. Concurrent ice-speed measurements show only minor changes, suggesting that ice dynamics are not strongly sensitive to changes in water flow.
In this paper we investigate elevation changes of Thwaites Glacier, West Antarctica, one of the...
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