eCite Digital Repository
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, The Cryosphere, 12 pp. 1047-1067. ISSN 1994-0432 (2018) [Refereed Article]
 | PDF 6Mb |
Copyright Statement
Copyright Author(s) 2018. Licensed under Creative Commons Attribution 3.0 Unported (CC BY 3.0) https://creativecommons.org/licenses/by/3.0/
DOI: doi:10.5194/tc-12-1047-2018
Abstract
The microstructure of polycrystalline ice evolves under prolonged deformation, leading to anisotropic patterns of crystal orientations. The response of this material to applied stresses is not adequately described by the ice flow relation most commonly 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, constitutive relation which addresses the influence of the dynamically steady-state flow-compatible induced anisotropic crystal orientation patterns that develop when ice is subjected to the same stress regime for a prolonged period – sometimes termed tertiary flow. We call this the ESTAR flow relation. The effect on ice flow dynamics is investigated by comparing idealised simulations using ESTAR and Glen flow relations, where we include in the latter an overall 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 in the ESTAR relation. Importantly, no single Glen enhancement factor can accurately capture the spatial variations in flow across the ice shelf generated by the ESTAR flow relation. For flow line studies of idealised grounded flow over varying topography or variable basal friction – both scenarios dominated at depth by bed-parallel shear – the differences between simulated velocities using ESTAR and Glen flow relations depend on the value of the enhancement factor used to calibrate the Glen flow relation. These results demonstrate the importance of describing the deformation of anisotropic 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: | Fluid mechanics and thermal engineering |
| Research Field: | Computational methods in fluid flow, heat and mass transfer (incl. computational fluid dynamics) |
| Objective Division: | Environmental Policy, Climate Change and Natural Hazards |
| Objective Group: | Understanding climate change |
| Objective Field: | Effects of climate change on Antarctic and sub-Antarctic environments (excl. social impacts) |
| UTAS Author: | Graham, FS (Dr Felicity McCormack) |
| UTAS Author: | Warner, RC (Dr Roland Warner) |
| UTAS Author: | Treverrow, A (Dr Adam Treverrow) |
| ID Code: | 116818 |
| Year Published: | 2018 |
| Web of Science® Times Cited: | 12 |
| Deposited By: | Oceans and Cryosphere |
| Deposited On: | 2017-05-23 |
| Last Modified: | 2018-11-26 |
| Downloads: | 72 View Download Statistics |
Repository Staff Only: item control page