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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2015
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Online Access: | https://escholarship.org/uc/item/4qt5b17z https://escholarship.org/content/qt4qt5b17z/qt4qt5b17z.pdf https://doi.org/10.3189/2015jog14j221 |
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ftcdlib:oai:escholarship.org:ark:/13030/qt4qt5b17z 2024-09-15T17:41:34+00:00 Marine ice-sheet profiles and stability under Coulomb basal conditions Tsai, Victor C Stewart, Andrew L Thompson, Andrew F 205 - 215 2015-01-01 application/pdf https://escholarship.org/uc/item/4qt5b17z https://escholarship.org/content/qt4qt5b17z/qt4qt5b17z.pdf https://doi.org/10.3189/2015jog14j221 unknown eScholarship, University of California qt4qt5b17z https://escholarship.org/uc/item/4qt5b17z https://escholarship.org/content/qt4qt5b17z/qt4qt5b17z.pdf doi:10.3189/2015jog14j221 public Journal of Glaciology, vol 61, iss 226 Climate Action Antarctic glaciology glacial rheology glacier mechanics glacier modelling ice-sheet modelling Physical Geography and Environmental Geoscience Meteorology & Atmospheric Sciences article 2015 ftcdlib https://doi.org/10.3189/2015jog14j221 2024-06-28T06:28:20Z 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 Journal of Glaciology 61 226 205 215 |
institution |
Open Polar |
collection |
University of California: eScholarship |
op_collection_id |
ftcdlib |
language |
unknown |
topic |
Climate Action Antarctic glaciology glacial rheology glacier mechanics glacier modelling ice-sheet modelling Physical Geography and Environmental Geoscience Meteorology & Atmospheric Sciences |
spellingShingle |
Climate Action Antarctic glaciology glacial rheology glacier mechanics glacier modelling ice-sheet modelling Physical Geography and Environmental Geoscience Meteorology & Atmospheric Sciences Tsai, Victor C Stewart, Andrew L Thompson, Andrew F Marine ice-sheet profiles and stability under Coulomb basal conditions |
topic_facet |
Climate Action Antarctic glaciology glacial rheology glacier mechanics glacier modelling ice-sheet modelling Physical Geography and Environmental Geoscience Meteorology & Atmospheric Sciences |
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, 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 |
eScholarship, University of California |
publishDate |
2015 |
url |
https://escholarship.org/uc/item/4qt5b17z https://escholarship.org/content/qt4qt5b17z/qt4qt5b17z.pdf https://doi.org/10.3189/2015jog14j221 |
op_coverage |
205 - 215 |
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 https://escholarship.org/content/qt4qt5b17z/qt4qt5b17z.pdf doi:10.3189/2015jog14j221 |
op_rights |
public |
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_ |
1810487786534338560 |