Modelling subglacial lakes and their influence on Antarctic ice sheet dynamics (Invited)
Abstract
Despite the large amount of subglacial lakes present underneath the East Antarctic Ice Sheet and the melt processes involved, the hydrology beneath the ice sheet is poorly understood. The ice flow across subglacial lakes can be regarded as the flow of an imbedded ice shelf, as the lake is an area of zero basal friction. Subglacial lakes influence ice flow in many ways, through an ice velocity speedup, changes in direction of ice flow and flattening of the ice surface. Recent satellite observations witness rapid changes in subglacial water volumes. Those subglacial lake outbursts discharge excess water through a subglacial drainage system underneath the ice sheet. Such processes can eventually lead to an ice flow speedup downstream of subglacial lake areas. Using a numerical higher-order ice sheet model that takes into account the ice flow over subglacial water bodies in hydrostatic equilibrium with the overlying ice, we were able to test the sensitivity of subglacial lakes to subglacial lake drainage. Experiments clearly demonstrate that small changes in surface slope are sufficient to start and sustain episodic subglacial drainage events. Therefore, lake drainage can be regarded as a common feature of the subglacial hydrological system and may influence to a large extent the present and future behavior of large ice sheets. Recently, a subglacial lake circulation model was dynamically coupled to this ice sheet model to investigate the sensitive interplay of melting and refreezing processes at the ice/water interface.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2009
- Bibcode:
- 2009AGUFM.U53C..06P
- Keywords:
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- 0798 CRYOSPHERE / Modeling