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
Received: 24 Jun 2013 – Discussion started: 08 Aug 2013
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.
Revised: 04 Jun 2014 – Accepted: 13 Jun 2014 – Published: 24 Jul 2014
Le Meur, E., Sacchettini, M., Garambois, S., Berthier, E., Drouet, A. S., Durand, G., Young, D., Greenbaum, J. S., Holt, J. W., Blankenship, D. D., Rignot, E., Mouginot, J., Gim, Y., Kirchner, D., de Fleurian, B., Gagliardini, O., and Gillet-Chaulet, F.: Two independent methods for mapping the grounding line of an outlet glacier – an example from the Astrolabe Glacier, Terre Adélie, Antarctica, The Cryosphere, 8, 1331-1346, doi:10.5194/tc-8-1331-2014, 2014.