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The Cryosphere An interactive open-access journal of the European Geosciences Union
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Volume 12, issue 9 | Copyright
The Cryosphere, 12, 2869-2882, 2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Research article 06 Sep 2018

Research article | 06 Sep 2018

Seasonal dynamics of Totten Ice Shelf controlled by sea ice buttressing

Chad A. Greene1, Duncan A. Young1, David E. Gwyther2, Benjamin K. Galton-Fenzi3,4, and Donald D. Blankenship1 Chad A. Greene et al.
  • 1Institute for Geophysics, Jackson School of Geosciences, University of Texas at Austin, Austin, Texas, USA
  • 2Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Tasmania, Australia
  • 3Australian Antarctic Division, Kingston, Tasmania 7050, Australia
  • 4Antarctic Climate & Ecosystems Cooperative Research Centre, University of Tasmania, Hobart, Tasmania 7001, Australia

Abstract. 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.

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Short summary
We show that Totten Ice Shelf accelerates each spring in response to the breakup of seasonal landfast sea ice at the ice shelf calving front. The previously unreported seasonal flow variability may have aliased measurements in at least one previous study of Totten's response to ocean forcing on interannual timescales. The role of sea ice in buttressing the flow of the ice shelf implies that long-term changes in sea ice cover could have impacts on the mass balance of the East Antarctic Ice Sheet.
We show that Totten Ice Shelf accelerates each spring in response to the breakup of seasonal...