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Lookup NU author(s): Professor Matt King
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Basal melting of ice shelves around Antarctica contributes to formation of Antarctic Bottom Water and can affect global sea level by altering the offshore flow of grounded ice streams and glaciers. Tides influence ice shelf basal melt rate (w(b)) by contributing to ocean mixing and mean circulation as well as thermohaline exchanges with the ice shelf. We use a three-dimensional ocean model, thermodynamically coupled to a nonevolving ice shelf, to investigate the relationship between topography, tides, and w(b) for Larsen C Ice Shelf (LCIS) in the northwestern Weddell Sea, Antarctica. Using our best estimates of ice shelf thickness and seabed topography, we find that the largest modeled LCIS melt rates occur in the northeast, where our model predicts strong diurnal tidal currents (similar to 0.4 m s(-1)). This distribution is significantly different from models with no tidal forcing, which predict largest melt rates along the deep grounding lines. We compare several model runs to explore melt rate sensitivity to geometry, initial ocean potential temperature (theta(0)), thermodynamic parameterizations of heat and freshwater ice-ocean exchange, and tidal forcing. The resulting range of LCIS-averaged w(b) is similar to 0.11-0.44 m a(-1). The spatial distribution of w(b) is very sensitive to model geometry and thermodynamic parameterization while the overall magnitude of w(b) is influenced by theta(0). These sensitivities in w(b) predictions reinforce a need for high-resolution maps of ice draft and sub-ice-shelf seabed topography together with ocean temperature measurements at the ice shelf front to improve representation of ice shelves in coupled climate system models.
Author(s): Mueller RD, Padman L, Dinniman MS, Erofeeva SY, Fricker HA, King MA
Publication type: Article
Publication status: Published
Journal: Journal of Geophysical Research: Oceans
Year: 2012
Volume: 117
Issue: 5
Print publication date: 01/05/2012
ISSN (print): 0148-0227
ISSN (electronic): 2156-2202
Publisher: American Geophysical Union
URL: http://dx.doi.org/10.1029/2011JC007263
DOI: 10.1029/2011JC007263
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