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An improved model for tidally modulated grounding-line migration

Tsai, Victor C.; Gudmundsson, G. Hilmar. 2015 An improved model for tidally modulated grounding-line migration. Journal of Glaciology, 61 (226). 216-222. 10.3189/2015JoG14J152

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Abstract/Summary

Understanding grounding-line dynamics is necessary for predictions of long-term ice-sheet stability. However, despite growing observations of the tidal influence on grounding-line migration, this short-timescale migration is poorly understood, with most modeling attempts assuming beam theory to calculate displacements. Here we present an improved model of tidal grounding-line migration that treats migration as an elastic fracture problem, forced by the additional ocean water pressure from the tide. This new model predicts that the grounding line cannot be assumed to be in hydrostatic equilibrium and, furthermore, that migration is inherently asymmetric and nonlinear, with migration distances that are not proportional to the tidal load. Specifically, for constant surface slope, the grounding line migrates upstream approximately ten times further as the tide rises from mean sea level to high tide than it migrates downstream as the tide falls from mean sea level to low tide, and migration distances are substantially larger than simple flotation arguments suggest. Numerical tests also show that the dependence of migration distance on elastic moduli and ice-sheet thickness are inconsistent with predictions of beam theory for a range of realistic values. Finally, applying the new model to observations in Antarctica results in new estimates of bed slopes, though these estimates remain uncertain due to imperfect knowledge of the relevant rheological parameters.

Item Type: Publication - Article
Digital Object Identifier (DOI): 10.3189/2015JoG14J152
Programmes: BAS Programmes > BAS Programmes 2015 > Ice Dynamics and Palaeoclimate
ISSN: 00221430
Additional Keywords: Antarctic glaciology, glacier mechanics, glacier modelling, ice/ocean interactions
Date made live: 01 Jul 2015 11:02 +0 (UTC)
URI: http://nora.nerc.ac.uk/id/eprint/511211

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