Preprints
https://doi.org/10.5194/egusphere-2024-1040
https://doi.org/10.5194/egusphere-2024-1040
21 May 2024
 | 21 May 2024
Status: this preprint is open for discussion.

Application of a regularised Coulomb sliding law to Jakobshavn Isbræ, West Greenland

Matt Trevers, Antony J. Payne, and Stephen L. Cornford

Abstract. Reliable projections of future sea level rise from the polar ice sheets depend on the ability of ice sheet models to accurately reproduce flow dynamics in an evolving ice sheet system. Ice sheet models are sensitive to the choice of basal sliding law, which remains a significant source of uncertainty. In this study we apply a range sliding laws to a hindcast model of Jakobshavn Isbræ, West Greenland from 2009 to 2018. We show that commonly used Weertman-like sliding laws can not reproduce the large seasonal and inter-annual variations in flow speed, while the assimilation of regular velocity observations into the model improves the model accuracy. We demonstrate that a regularised Coulomb friction law, in which basal traction has an upper limit, was able to reproduce the peak flow speeds most accurately. Finally we find evidence that the speed at which sliding transitions between power-law and Coulomb regimes may vary spatially and temporally. These results point towards the possible form of an ideal sliding law for accurately modelling fast-flowing glaciers and ice streams.

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Matt Trevers, Antony J. Payne, and Stephen L. Cornford

Status: open (until 15 Jul 2024)

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Matt Trevers, Antony J. Payne, and Stephen L. Cornford
Matt Trevers, Antony J. Payne, and Stephen L. Cornford

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Short summary
The form of the friction law which determines the speed of ice sliding over the bedrock remains a major source of uncertainty in ice sheet model projections of future sea level rise. Jakobshavn Isbræ, the fastest flowing glacier in Greenland which has undergone significant changes in the last few decades, is an ideal case for testing sliding laws. We find that a regularised Coulomb friction law reproduces the large seasonal and interannual flow speed variations most accurately.