Processes controlling the downstream evolution of ice rheology in glacier shear margins: case study on Rutford Ice Stream, West Antarctica

Minchew, Brent M., Meyer, Colin R., Robel, Alexander A., Gudmundsson, Hilmar and Simons, Mark (2018) Processes controlling the downstream evolution of ice rheology in glacier shear margins: case study on Rutford Ice Stream, West Antarctica. Journal of Glaciology, 64 (246). pp. 583-594. ISSN 0022-1430

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Official URL: https://doi.org/10.1017/jog.2018.47

Abstract

Ice rheology governs how glaciers flow and respond to environmental change. The rheology of glacier ice evolves in response to a variety of mechanisms, including damage, heating, melting and the development of crystalline fabric. The relative contributions of these rheological mechanisms are not well understood. Using remotely sensed data and physical models, we decouple the influence of each of the aforementioned mechanisms along the margins of Rutford Ice Stream, a laterally confined outlet glacier in West Antarctica. We show that fabric is an important control on ice rheology in the shear margins, with an inferred softening effect consistent with a single-maximum fabric. Fabric evolves to steady state near the onset of streaming flow, and ice progressively softens downstream almost exclusively due to shear heating. The rate of heating is sensitive to local shear strain rates, which respond to local changes in bed topography as ice is squeezed through the basal trough. The impact of shear heating on the downstream evolution of ice rheology in a laterally confined glacier suggests that the thermoviscous feedback – wherein faster ice flow leads to higher rates of shear heating, further softening the ice – is a fundamental control on glacier dynamics.

Item Type: Article
Additional Information: Funding information: B.M.M. was funded by an NSF Earth Sciences Postdoctoral Fellowship award EAR-1452587. C.R.M. was supported by an NSF Graduate Research Fellowship, award DGE1144152 and a David Crighton Fellowship. A.A.R. was funded through a NOAA Climate & Global Change Postdoctoral Fellowship and the Caltech Stanback Postdoctoral Fellowship.
Uncontrolled Keywords: Anisotropic ice flow, Antarctic glaciology, glacial rheology, glacier flow, ice rheology
Subjects: F800 Physical and Terrestrial Geographical and Environmental Sciences
Department: Faculties > Engineering and Environment > Geography and Environmental Sciences
Depositing User: Paul Burns
Date Deposited: 11 Jul 2018 16:44
Last Modified: 18 Nov 2021 15:45
URI: http://nrl.northumbria.ac.uk/id/eprint/34943

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