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The Cryosphere An interactive open-access journal of the European Geosciences Union
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Volume 12, issue 8 | Copyright
The Cryosphere, 12, 2653-2666, 2018
https://doi.org/10.5194/tc-12-2653-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Research article 15 Aug 2018

Research article | 15 Aug 2018

Basal friction of Fleming Glacier, Antarctica – Part 2: Evolution from 2008 to 2015

Chen Zhao1,3, Rupert M. Gladstone2, Roland C. Warner3, Matt A. King1, Thomas Zwinger4, and Mathieu Morlighem5 Chen Zhao et al.
  • 1School of Technology, Environments and Design, University of Tasmania, Hobart, Australia
  • 2Arctic Centre, University of Lapland, Rovaniemi, Finland
  • 3Antarctic Climate & Ecosystems Cooperative Research Centre, University of Tasmania, Hobart, Australia
  • 4CSC – IT Center for Science Ltd., Espoo, Finland
  • 5Department of Earth System Science, University of California, Irvine, CA 92697-3100, USA

Abstract. The Wordie Ice Shelf–Fleming Glacier system in the southern Antarctic Peninsula has experienced a long-term retreat and disintegration of its ice shelf in the past 50 years. Increases in the glacier velocity and dynamic thinning have been observed over the past two decades, especially after 2008 when only a small ice shelf remained at the Fleming Glacier front. It is important to know whether the substantial further speed-up and greater surface draw-down of the glacier since 2008 is a direct response to ocean forcing, or driven by feedbacks within the grounded marine-based glacier system, or both. Recent observational studies have suggested the 2008–2015 velocity change was due to the ungrounding of the Fleming Glacier front. To explore the mechanisms underlying the recent changes, we use a full-Stokes ice sheet model to simulate the basal shear stress distribution of the Fleming system in 2008 and 2015. This study is part of the first high resolution modelling campaign of this system. Comparison of inversions for basal shear stresses for 2008 and 2015 suggests the migration of the grounding line  ∼ 9km upstream by 2015 from the 2008 ice front/grounding line positions, which virtually coincided with the 1996 grounding line position. This migration is consistent with the change in floating area deduced from the calculated height above buoyancy in 2015. The retrograde submarine bed underneath the lowest part of the Fleming Glacier may have promoted retreat of the grounding line. Grounding line retreat may also be enhanced by a feedback mechanism upstream of the grounding line by which increased basal lubrication due to increasing frictional heating enhances sliding and thinning. Improved knowledge of bed topography near the grounding line and further transient simulations with oceanic forcing are required to accurately predict the future movement of the Fleming Glacier system grounding line and better understand its ice dynamics and future contribution to sea level.

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A combination of computer modelling and observational data were used to infer the resistance to ice flow at the bed of the Fleming Glacier on the Antarctic Peninsula in both 2008 and 2015. The comparison suggests the grounding line retreated by ~ 9 km from 2008 to 2015. The retreat may be enhanced by a positive feedback between friction, melting and sliding at the glacier bed.
A combination of computer modelling and observational data were used to infer the resistance to...
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