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Previous studies of Totten Ice Shelf have employed surface velocity measurements to estimate its mass balance and understand its sensitivities to interannual changes in climate forcing. However, displacement measurements acquired over timescales of days to weeks may not accurately characterize long-term flow rates wherein ice velocity fluctuates with the seasons. Quantifying annual mass budgets or analyzing interannual changes in ice velocity requires knowing when and where observations of glacier velocity could be aliased by subannual variability. Here, we analyze 16 years of velocity data for Totten Ice Shelf, which we generate at subannual resolution by applying feature-tracking algorithms to several hundred satellite image pairs. We identify a seasonal cycle characterized by a spring to autumn speedup of more than 100myr⁻¹ close to the ice front. The amplitude of the seasonal cycle diminishes with distance from the open ocean, suggesting the presence of a resistive back stress at the ice front that is strongest in winter. Springtime acceleration precedes summer surface melt and is not attributable to thinning from basal melt. We attribute the onset of ice shelf acceleration each spring to the loss of buttressing from the breakup of seasonal landfast sea ice.

Item Type:	Refereed Article
Keywords:	Antarctica, Totten Glacier, ice sheet, sea ice
Research Division:	Earth Sciences
Research Group:	Oceanography
Research Field:	Physical Oceanography
Objective Division:	Environment
Objective Group:	Other Environment
Objective Field:	Antarctic and Sub-Antarctic Oceanography
Author:	Gwyther, DE (Dr David Gwyther)
Author:	Galton-Fenzi, BK (Dr Ben Galton-Fenzi)
ID Code:	128201
Year Published:	2018
Deposited By:	Oceans and Cryosphere
Deposited On:	2018-09-07
Last Modified:	2018-10-09
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