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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ftcdlib:oai:escholarship.org/ark:/13030/qt4qt5b17z 2023-05-15T14:01:12+02:00 Marine ice-sheet profiles and stability under Coulomb basal conditions Tsai, VC Stewart, AL Thompson, AF 205 - 215 2015-05-01 application/pdf https://escholarship.org/uc/item/4qt5b17z unknown eScholarship, University of California qt4qt5b17z https://escholarship.org/uc/item/4qt5b17z public Journal of Glaciology, vol 61, iss 226 Antarctic glaciology glacial rheology glacier mechanics glacier modelling ice-sheet modelling Meteorology & Atmospheric Sciences Physical Geography and Environmental Geoscience article 2015 ftcdlib 2021-12-06T18:18:02Z 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. Article in Journal/Newspaper Antarc* Antarctic Ice Sheet Journal of Glaciology University of California: eScholarship Antarctic West Antarctic Ice Sheet |
institution |
Open Polar |
collection |
University of California: eScholarship |
op_collection_id |
ftcdlib |
language |
unknown |
topic |
Antarctic glaciology glacial rheology glacier mechanics glacier modelling ice-sheet modelling Meteorology & Atmospheric Sciences Physical Geography and Environmental Geoscience |
spellingShingle |
Antarctic glaciology glacial rheology glacier mechanics glacier modelling ice-sheet modelling Meteorology & Atmospheric Sciences Physical Geography and Environmental Geoscience Tsai, VC Stewart, AL Thompson, AF Marine ice-sheet profiles and stability under Coulomb basal conditions |
topic_facet |
Antarctic glaciology glacial rheology glacier mechanics glacier modelling ice-sheet modelling Meteorology & Atmospheric Sciences Physical Geography and Environmental Geoscience |
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. |
format |
Article in Journal/Newspaper |
author |
Tsai, VC Stewart, AL Thompson, AF |
author_facet |
Tsai, VC Stewart, AL Thompson, AF |
author_sort |
Tsai, VC |
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 |
eScholarship, University of California |
publishDate |
2015 |
url |
https://escholarship.org/uc/item/4qt5b17z |
op_coverage |
205 - 215 |
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, vol 61, iss 226 |
op_relation |
qt4qt5b17z https://escholarship.org/uc/item/4qt5b17z |
op_rights |
public |
_version_ |
1766270790562480128 |