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The Cryosphere An interactive open-access journal of the European Geosciences Union
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Volume 12, issue 7 | Copyright
The Cryosphere, 12, 2425-2436, 2018
https://doi.org/10.5194/tc-12-2425-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Research article 25 Jul 2018

Research article | 25 Jul 2018

Simulated dynamic regrounding during marine ice sheet retreat

Lenneke M. Jong1,2,3, Rupert M. Gladstone2,4, Benjamin K. Galton-Fenzi1,2, and Matt A. King5 Lenneke M. Jong et al.
  • 1Australian Antarctic Division, Channel Highway, Kingston, Tasmania 7050, Australia
  • 2Antarctic Climate & Ecosystems Cooperative Research Centre, University of Tasmania, Private Bag 80, Hobart, Tasmania 7001, Australia
  • 3Institute for Marine and Antarctic Studies, University of Tasmania, Private Bag 129, Hobart, Tasmania 7001, Australia
  • 4Arctic Centre, University of Lapland, P.O. Box 122, 96101, Rovaniemi, Finland
  • 5School of Technology, Environments and Design, University of Tasmania, Hobart 7001, Australia

Abstract. Marine-terminating ice sheets are of interest due to their potential instability, making them vulnerable to rapid retreat. Modelling the evolution of glaciers and ice streams in such regions is key to understanding their possible contribution to sea level rise. The friction caused by the sliding of ice over bedrock and the resultant shear stress are important factors in determining the velocity of sliding ice. Many models use simple power-law expressions for the relationship between the basal shear stress and ice velocity or introduce an effective-pressure dependence into the sliding relation in an ad hoc manner. Sliding relations based on water-filled subglacial cavities are more physically motivated, with the overburden pressure of the ice included. Here we show that using a cavitation-based sliding relation allows for the temporary regrounding of an ice shelf at a point downstream of the main grounding line of a marine ice sheet undergoing retreat across a retrograde bedrock slope. This suggests that the choice of sliding relation is especially important when modelling grounding line behaviour of regions where potential ice rises and pinning points are present and regrounding could occur.

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We used an ice sheet model to simulate temporary regrounding of a marine ice sheet retreating across a retrograde bedrock slope. We show that a sliding relation incorporating water-filled cavities and the ice overburden pressure at the base allows the temporary regrounding to occur. This suggests that choice of basal sliding relation can be important when modelling grounding line behaviour of regions where potential ice rises and pinning points are present and regrounding could occur.
We used an ice sheet model to simulate temporary regrounding of a marine ice sheet retreating...
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