1Laboratoire de Glaciologie, Université Libre de Bruxelles, CP160/03, Av. F. Roosevelt 50, 1050 Brussels, Belgium
2Dept. of Earth and Ocean Sciences, University of British Columbia, 6339 Stores Road, Vancouver, BC V6T 1Z4, Canada
3Physical Science Division, British Antarctic Survey, Natural Environment Research Council, High Cross, Madingley Road, Cambridge CB3 0ET, UK
4Department of Mathematics and Geophysical Institute, University of Alaska, Fairbanks, USA
5Laboratoire de Glaciologie et de Géophysique de l'Environnement (LGGE), CNRS, UJF-Grenoble I, BP 96, 38402 Saint Martin d'Hères Cedex, France
6Bristol Glaciology Centre, School of Geographical Sciences, University Road, University of Bristol, Bristol BS8 1SS, UK
7Courant Institute of Mathematical Sciences, New York University, New York, USA
8Earth and Environmental Systems Institute, College of Earth and Mineral Sciences, 2217 Earth-Engineering Sciences Bldg., Pennsylvania State University, University Park, PA 16802, USA
9Earth System Sciences & Department of Geography, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium
10Frontier Research Center for Global Change, 3173-25 Showamachi, Kanazawa-ku, Yokohama City, Kanagawa 236-0001, Japan
11Department of Geography, Durham University, Durham, UK
12Institute for Marine and Atmospheric research, Utrecht University, Utrecht, The Netherlands
Received: 23 Dec 2011 – Discussion started: 24 Jan 2012
Abstract. Predictions of marine ice-sheet behaviour require models that are able to robustly simulate grounding line migration. We present results of an intercomparison exercise for marine ice-sheet models. Verification is effected by comparison with approximate analytical solutions for flux across the grounding line using simplified geometrical configurations (no lateral variations, no effects of lateral buttressing). Unique steady state grounding line positions exist for ice sheets on a downward sloping bed, while hysteresis occurs across an overdeepened bed, and stable steady state grounding line positions only occur on the downward-sloping sections. Models based on the shallow ice approximation, which does not resolve extensional stresses, do not reproduce the approximate analytical results unless appropriate parameterizations for ice flux are imposed at the grounding line. For extensional-stress resolving "shelfy stream" models, differences between model results were mainly due to the choice of spatial discretization. Moving grid methods were found to be the most accurate at capturing grounding line evolution, since they track the grounding line explicitly. Adaptive mesh refinement can further improve accuracy, including fixed grid models that generally perform poorly at coarse resolution. Fixed grid models, with nested grid representations of the grounding line, are able to generate accurate steady state positions, but can be inaccurate over transients. Only one full-Stokes model was included in the intercomparison, and consequently the accuracy of shelfy stream models as approximations of full-Stokes models remains to be determined in detail, especially during transients.
Revised: 13 Apr 2012 – Accepted: 07 May 2012 – Published: 30 May 2012
Pattyn, F., Schoof, C., Perichon, L., Hindmarsh, R. C. A., Bueler, E., de Fleurian, B., Durand, G., Gagliardini, O., Gladstone, R., Goldberg, D., Gudmundsson, G. H., Huybrechts, P., Lee, V., Nick, F. M., Payne, A. J., Pollard, D., Rybak, O., Saito, F., and Vieli, A.: Results of the Marine Ice Sheet Model Intercomparison Project, MISMIP, The Cryosphere, 6, 573-588, doi:10.5194/tc-6-573-2012, 2012.