Marine ice-sheet profiles and stability under Coulomb basal conditions
The behavior of marine-terminating ice sheets, such as the West Antarctic ice sheet, is of interest due to the possibility of rapid grounding-line retreat and consequent catastrophic loss of ice. Critical to modeling this behavior is a choice of basal rheology, where the most popular approach is to...
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ftcaltechauth:oai:authors.library.caltech.edu:7fyvt-gpa58 2024-06-23T07:47:55+00:00 Marine ice-sheet profiles and stability under Coulomb basal conditions Tsai, Victor C. Stewart, Andrew L. Thompson, Andrew F. 2015 https://doi.org/10.3189/2015JoG14J221 unknown International Glaciological Society https://doi.org/10.3189/2015JoG14J221 oai:authors.library.caltech.edu:7fyvt-gpa58 eprintid:55701 resolverid:CaltechAUTHORS:20150311-105436730 info:eu-repo/semantics/openAccess Other Journal of Glaciology, 61(226), 205-215, (2015) Antarctic glaciology glacial rheology glacier mechanics glacier modelling ice-sheet modelling info:eu-repo/semantics/article 2015 ftcaltechauth https://doi.org/10.3189/2015JoG14J221 2024-06-12T03:59:00Z The behavior of marine-terminating ice sheets, such as the West Antarctic ice sheet, is of interest due to the possibility of rapid grounding-line retreat and consequent catastrophic loss of ice. Critical to modeling this behavior is a choice of basal rheology, where the most popular approach is to relate the ice-sheet velocity to a power-law function of basal stress. Recent experiments, however, suggest that near-grounding line tills exhibit Coulomb friction behavior. Here we address how Coulomb conditions modify ice-sheet profiles and stability criteria. The basal rheology necessarily transitions to Coulomb friction near the grounding line, due to low effective stresses, leading to changes in ice-sheet properties within a narrow boundary layer. Ice-sheet profiles 'taper off' towards a flatter upper surface, compared with the power-law case, and basal stresses vanish at the grounding line, consistent with observations. In the Coulomb case, the grounding-line ice flux also depends more strongly on flotation ice thickness, which implies that ice sheets are more sensitive to climate perturbations. Furthermore, with Coulomb friction, the ice sheet grounds stably in shallower water than with a power-law rheology. This implies that smaller perturbations are required to push the grounding line into regions of negative bed slope, where it would become unstable. These results have important implications for ice-sheet stability in a warming climate. © 2015 IGS. MS received 17 November 2014 and accepted in revised form 14 February 2015. We thank G.H. Gudmundsson for useful discussions, and two anonymous reviewers for helpful suggestions. This research was carried out at the Jet Propulsion Laboratory and the California Institute of Technology under a contract with the National Aeronautics and Space Administration and funded through the President's and Director's Fund Program. Partial support was also provided by the Stanback Discovery Fund for Global Environmental Science. Published - t14j221.pdf Article in Journal/Newspaper Antarc* Antarctic Ice Sheet Journal of Glaciology Caltech Authors (California Institute of Technology) Antarctic West Antarctic Ice Sheet Journal of Glaciology 61 226 205 215 |
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Open Polar |
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Caltech Authors (California Institute of Technology) |
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ftcaltechauth |
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unknown |
topic |
Antarctic glaciology glacial rheology glacier mechanics glacier modelling ice-sheet modelling |
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Antarctic glaciology glacial rheology glacier mechanics glacier modelling ice-sheet modelling Tsai, Victor C. Stewart, Andrew L. Thompson, Andrew F. Marine ice-sheet profiles and stability under Coulomb basal conditions |
topic_facet |
Antarctic glaciology glacial rheology glacier mechanics glacier modelling ice-sheet modelling |
description |
The behavior of marine-terminating ice sheets, such as the West Antarctic ice sheet, is of interest due to the possibility of rapid grounding-line retreat and consequent catastrophic loss of ice. Critical to modeling this behavior is a choice of basal rheology, where the most popular approach is to relate the ice-sheet velocity to a power-law function of basal stress. Recent experiments, however, suggest that near-grounding line tills exhibit Coulomb friction behavior. Here we address how Coulomb conditions modify ice-sheet profiles and stability criteria. The basal rheology necessarily transitions to Coulomb friction near the grounding line, due to low effective stresses, leading to changes in ice-sheet properties within a narrow boundary layer. Ice-sheet profiles 'taper off' towards a flatter upper surface, compared with the power-law case, and basal stresses vanish at the grounding line, consistent with observations. In the Coulomb case, the grounding-line ice flux also depends more strongly on flotation ice thickness, which implies that ice sheets are more sensitive to climate perturbations. Furthermore, with Coulomb friction, the ice sheet grounds stably in shallower water than with a power-law rheology. This implies that smaller perturbations are required to push the grounding line into regions of negative bed slope, where it would become unstable. These results have important implications for ice-sheet stability in a warming climate. © 2015 IGS. MS received 17 November 2014 and accepted in revised form 14 February 2015. We thank G.H. Gudmundsson for useful discussions, and two anonymous reviewers for helpful suggestions. This research was carried out at the Jet Propulsion Laboratory and the California Institute of Technology under a contract with the National Aeronautics and Space Administration and funded through the President's and Director's Fund Program. Partial support was also provided by the Stanback Discovery Fund for Global Environmental Science. Published - t14j221.pdf |
format |
Article in Journal/Newspaper |
author |
Tsai, Victor C. Stewart, Andrew L. Thompson, Andrew F. |
author_facet |
Tsai, Victor C. Stewart, Andrew L. Thompson, Andrew F. |
author_sort |
Tsai, Victor C. |
title |
Marine ice-sheet profiles and stability under Coulomb basal conditions |
title_short |
Marine ice-sheet profiles and stability under Coulomb basal conditions |
title_full |
Marine ice-sheet profiles and stability under Coulomb basal conditions |
title_fullStr |
Marine ice-sheet profiles and stability under Coulomb basal conditions |
title_full_unstemmed |
Marine ice-sheet profiles and stability under Coulomb basal conditions |
title_sort |
marine ice-sheet profiles and stability under coulomb basal conditions |
publisher |
International Glaciological Society |
publishDate |
2015 |
url |
https://doi.org/10.3189/2015JoG14J221 |
geographic |
Antarctic West Antarctic Ice Sheet |
geographic_facet |
Antarctic West Antarctic Ice Sheet |
genre |
Antarc* Antarctic Ice Sheet Journal of Glaciology |
genre_facet |
Antarc* Antarctic Ice Sheet Journal of Glaciology |
op_source |
Journal of Glaciology, 61(226), 205-215, (2015) |
op_relation |
https://doi.org/10.3189/2015JoG14J221 oai:authors.library.caltech.edu:7fyvt-gpa58 eprintid:55701 resolverid:CaltechAUTHORS:20150311-105436730 |
op_rights |
info:eu-repo/semantics/openAccess Other |
op_doi |
https://doi.org/10.3189/2015JoG14J221 |
container_title |
Journal of Glaciology |
container_volume |
61 |
container_issue |
226 |
container_start_page |
205 |
op_container_end_page |
215 |
_version_ |
1802638179936763904 |