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Sliding Relations for Glacier Slip With Cavities Over Three-Dimensional Beds

Abstract : Results of glacier flow models and associated estimates of future sea level rise depend sensitively on the prescribed relation between shear stress and slip velocity at the glacier bed. Using a fully three-dimensional numerical model of ice flow, we compute steady-state sliding relations for where ice slips over a rock bed with three-dimensional, periodic topography. In agreement with studies of two-dimensional beds, water-filled cavities that form down-glacier from bedforms cause basal shear stress to peak at a threshold slip velocity and decrease at higher velocities (i.e., rate-weakening drag). However, the shear stress magnitude and extent of rate-weakening drag depend systematically on lateral topographic variations not considered previously. Moreover, steep up-glacier-facing slopes of bedforms can result in shear stress that increases monotonically over a wide range of slip velocity, helping to stabilize slip. These results highlight the potential variability of sliding relations and their likely sensitivity to the morphological diversity of glacier beds.
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Submitted on : Tuesday, June 28, 2022 - 8:55:39 AM
Last modification on : Wednesday, June 29, 2022 - 3:32:37 AM

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Christian Helanow, Neal R. Iverson, Lucas K. Zoet, Olivier Gagliardini. Sliding Relations for Glacier Slip With Cavities Over Three-Dimensional Beds. Geophysical Research Letters, 2020, 47, ⟨10.1029/2019GL084924⟩. ⟨insu-03706476⟩

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