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Implementing an empirical scalar constitutive relation for ice with flow-induced polycrystalline anisotropy in large-scale ice sheet models

Citation

Graham, FS and Morlighem, M and Warner, RC and Treverrow, A, Implementing an empirical scalar constitutive relation for ice with flow-induced polycrystalline anisotropy in large-scale ice sheet models, Cryosphere, 12 pp. 1047-1067. ISSN 1994-0432 (2018) [Refereed Article]


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Copyright Statement

Copyright 2017 Author(s). Licensed under Creative Commons Attribution 3.0 Unported (CC BY 3.0) https://creativecommons.org/licenses/by/3.0/

DOI: doi:10.5194/tc-2017-54

Abstract

The microstructural evolution that occurs in polycrystalline ice during deformation leads to the development of anisotropic rheological properties that are not adequately described by the most common, isotropic, ice flow relation used in large-scale ice sheet models the Glen flow relation. We present a preliminary assessment of the implementation in the Ice Sheet System Model (ISSM) of a computationally-efficient, empirical, scalar, tertiary, anisotropic rheology (ESTAR). The effect of this anisotropic rheology on ice flow dynamics is investigated by comparing idealised simulations using ESTAR with those using the isotropic Glen flow relation, where the latter includes a flow enhancement factor. For an idealised embayed ice shelf, the Glen flow relation overestimates velocities by up to 17 % when using an enhancement factor equivalent to the maximum value prescribed by ESTAR. Importantly, no single Glen enhancement factor can accurately capture the spatial variations in flow over the ice shelf. For flow-line studies of idealised grounded flow over a bumpy topography or a sticky base both scenarios dominated at depth by bed-parallel shear the differences between simulated velocities using ESTAR and the Glen flow relation vary according to the value of the enhancement factor used to calibrate the Glen flow relation. These results demonstrate the importance of describing the anisotropic rheology of ice in a physically realistic manner, and have implications for simulations of ice sheet evolution used to reconstruct paleo-ice sheet extent and predict future ice sheet contributions to sea level.

Item Details

Item Type:Refereed Article
Keywords:ice dynamics, rheology
Research Division:Engineering
Research Group:Interdisciplinary Engineering
Research Field:Computational Fluid Dynamics
Objective Division:Environment
Objective Group:Climate and Climate Change
Objective Field:Effects of Climate Change and Variability on Antarctic and Sub-Antarctic Environments (excl. Social Impacts)
Author:Graham, FS (Dr Felicity Graham)
Author:Warner, RC (Dr Roland Warner)
Author:Treverrow, A (Dr Adam Treverrow)
ID Code:116818
Year Published:2018
Deposited By:Oceans and Cryosphere
Deposited On:2017-05-23
Last Modified:2018-04-16
Downloads:13 View Download Statistics

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