State of the Arctic and Antarctic sea ice covers from Operation IceBridge snow and ice thickness observations
Abstract
We present a model of subglacial water flow below ice sheets, and particularly below ice streams. This hydrologic model is coupled to a vertically integrated model for ice flow that describes vertical, lateral, and longitudinal stresses. We show that under some conditions, this coupled system gives rise to ice streams by instability of the internal dynamics. The base-level water flow is fed by subglacial melting and is presumed to take the form of a Weertman-Creyts-Schoof rough-bedded film, in which the ice is supported by larger clasts, but there is a millimetric water film which submerges the smaller particles. A model for the film is given by two coupled partial differential equations, representing mass conservation of water and ice closure. We assume there is no sediment transport, and solve for water film depth, H, and effective pressure, N. If there is sufficiently small amount of meltwater produced (e.g. if ice flux is low), the distributed film is stable, while for larger amounts of melt, the ice-water system can become unstable, and ice streams form spontaneously as a consequence. We show that this can be explained as a result of a multivalued flux law, which arises from a simplified, one-dimensional analysis of the coupled model.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2011
- Bibcode:
- 2011AGUFM.C52B..02K
- Keywords:
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- 0736 CRYOSPHERE / Snow;
- 0750 CRYOSPHERE / Sea ice;
- 0758 CRYOSPHERE / Remote sensing;
- 0794 CRYOSPHERE / Instruments and techniques;
- 0726 CRYOSPHERE Ice sheets;
- 0730 CRYOSPHERE Ice streams;
- 0798 CRYOSPHERE Modeling