Impact of tide-topography interactions on basal melting of Larsen C Ice Shelf, Antarctica

• Published in: Journal of Geophysical Research: Oceans
• Main Authors: Mueller, RD, Padman, L, Dinniman, MS, Erofeeva, SY, Fricker, HA, King, MA
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley-Blackwell Publishing 2012
• Subjects: Earth Sciences; Geophysics; Geodesy; Weddell; Weddell Sea; Antarc*; Antarctica; Antarctica Journal; Ice Shelf; Ice Shelves
• Online Access: https://doi.org/10.1029/2011JC007263; http://ecite.utas.edu.au/89657

Basal melting of ice shelves around Antarctica contributes to formation ofAntarctic Bottom Water and can affect global sea level by altering the offshore flow ofgrounded ice streams and glaciers. Tides influence ice shelf basal melt rate ( w b ) bycontributing to ocean mixing and mean circulation as well as thermohaline exchangeswith the ice shelf. We use a three-dimensional ocean model, thermodynamicallycoupled 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, wefind that the largest modeled LCIS melt rates occur in the northeast, where our modelpredicts strong diurnal tidal currents (~0.4 m s -1 ). This distribution is significantlydifferent from models with no tidal forcing, which predict largest melt rates along the deepgrounding lines. We compare several model runs to explore melt rate sensitivity togeometry, initial ocean potential temperature ( θ 0 ), thermodynamic parameterizations ofheat and freshwater ice-ocean exchange, and tidal forcing. The resulting range ofLCIS-averaged wb is ~0.11-0.44 m a -1 . The spatial distribution of w b is verysensitive to model geometry and thermodynamic parameterization while the overallmagnitude of w b is influenced by O 0 . These sensitivities in w b predictions reinforce a needfor high-resolution maps of ice draft and sub-ice-shelf seabed topography together withocean temperature measurements at the ice shelf front to improve representation of iceshelves in coupled climate system models.