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The Cryosphere An interactive open-access journal of the European Geosciences Union
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Volume 8, issue 4
The Cryosphere, 8, 1331–1346, 2014
https://doi.org/10.5194/tc-8-1331-2014
© Author(s) 2014. This work is distributed under
the Creative Commons Attribution 3.0 License.

Special issue: Earth observation of the Cryosphere

The Cryosphere, 8, 1331–1346, 2014
https://doi.org/10.5194/tc-8-1331-2014
© Author(s) 2014. This work is distributed under
the Creative Commons Attribution 3.0 License.

Research article 24 Jul 2014

Research article | 24 Jul 2014

Two independent methods for mapping the grounding line of an outlet glacier – an example from the Astrolabe Glacier, Terre Adélie, Antarctica

E. Le Meur1,2, M. Sacchettini1,2, S. Garambois3, E. Berthier4, A. S. Drouet1,2, G. Durand1,2, D. Young5, J. S. Greenbaum5, J. W. Holt5, D. D. Blankenship5, E. Rignot6,7, J. Mouginot6, Y. Gim7, D. Kirchner8, B. de Fleurian1,2, O. Gagliardini1,2,9, and F. Gillet-Chaulet1,2 E. Le Meur et al.
  • 1CNRS, LGGE, UMR5183, 38041 Grenoble, France
  • 2Université de Grenoble Alpes, LGGE, UMR5183, 38041 Grenoble, France
  • 3ISTerre, UJF–Grenoble, CNRS, Saint Martin d'Héres, France
  • 4LEGOS, CNRS, Université de Toulouse, Toulouse, France
  • 5Institute for Geophysics, University of Texas, Texas, USA
  • 6Earth System Science, University of California, Irvine, California, USA
  • 7Jet Propulsion Laboratory, California, Institute of Technology, Pasadena, California, USA
  • 8University of Iowa, Department of Physics and Astronomy, Iowa City, Iowa, USA
  • 9Institut Universitaire de France, Paris, France

Abstract. The grounding line is a key element of coastal outlet glaciers, acting on their dynamics. Accurately knowing its position is fundamental for both modelling the glacier dynamics and establishing a benchmark for later change detection. Here we map the grounding line of the Astrolabe Glacier in East Antarctica (66°41' S, 140°05' E), using both hydrostatic and tidal methods. The first method is based on new surface and ice thickness data from which the line of buoyant floatation is found. The second method uses kinematic GPS measurements of the tidal response of the ice surface. By detecting the transitions where the ice starts to move vertically in response to the tidal forcing we determine control points for the grounding line position along GPS profiles. Employing a two-dimensional elastic plate model, we compute the rigid short-term behaviour of the ice plate and estimate the correction required to compare the kinematic GPS control points with the previously determined line of floatation. These two approaches show consistency and lead us to propose a grounding line for the Astrolabe Glacier that significantly deviates from the lines obtained so far from satellite imagery.

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