Cyclic behaviour on millennial time scale due to creep instabilities in western Dronning Maud Land, Antarctica
At the base of a thick ice sheet the temperature locally reaches the pressure melting point and melting generates a thin subglacial water layer. The basal water lubricates the base and thus enhances the sliding of the ice sheet. As a consequence of sliding, the heat source of internal strain heating...
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Geophysical Research Abstracts
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ftawi:oai:epic.awi.de:32911 2023-05-15T13:40:26+02:00 Cyclic behaviour on millennial time scale due to creep instabilities in western Dronning Maud Land, Antarctica Kleiner, Thomas Humbert, Angelika 2013 application/pdf https://epic.awi.de/id/eprint/32911/ https://epic.awi.de/id/eprint/32911/1/EGU2013-9732.pdf https://hdl.handle.net/10013/epic.41449 https://hdl.handle.net/10013/epic.41449.d001 unknown Geophysical Research Abstracts https://epic.awi.de/id/eprint/32911/1/EGU2013-9732.pdf https://hdl.handle.net/10013/epic.41449.d001 Kleiner, T. orcid:0000-0001-7825-5765 and Humbert, A. (2013) Cyclic behaviour on millennial time scale due to creep instabilities in western Dronning Maud Land, Antarctica , EGU General Assembly, Vienna, 7 April 2013 - 12 April 2013 . hdl:10013/epic.41449 EPIC3EGU General Assembly, Vienna, 2013-04-07-2013-04-12Vol. 15, EGU2013-9732, Geophysical Research Abstracts Conference notRev 2013 ftawi 2021-12-24T15:38:37Z At the base of a thick ice sheet the temperature locally reaches the pressure melting point and melting generates a thin subglacial water layer. The basal water lubricates the base and thus enhances the sliding of the ice sheet. As a consequence of sliding, the heat source of internal strain heating decreases and the basal ice cools down over time. When frictional heat and heat advection do not counterbalance this, the ice will become frozen to the bedrock again. In addition, strain heating within a temperate ice layer generates a liquid water fraction in the ice, leading to a softer material and enhanced deformation. If the horizontal or vertical advection of cold ice to the base is weak, this positive feedback will lead to a local creep instability. The effect of basal water is thus twofold: it affects the sliding, as well as the rheology and via both ways the ice dynamics. Subglacial water is therefore a crucial component in the dynamic evolution of ice sheets. We present numerical simulations of the present day ice flow using the three-dimensional thermo-coupled full- Stokes model TIM FD 3 on a 2.5 km horizontal grid in the area of the western Dronning Maud Land, Antarc- tica, including the three ice streams Stancomb-Wills, Veststraumen and Plogbreen and the adjacent Brunt and Riiser- Larsen ice shelves. Three different flux routing algorithms for the subglacial meltwater and a modified Weertman-type sliding relation were implemented in the model to account for higher sliding velocities under wet basal conditions. Subsequent to spin-up simulations different sliding simulations considering wet and dry basal conditions were performed. The simulations show a cyclic behaviour on millennial time scale at distinct locations in the model domain. We estimate the distribution of subglacial water based on different flux routing methods and the effect on the ice flow and the basal thermal regime. We further present our analysis of the involved feedback mechanism between ice flow, temperature and rheology, that are related to the simulated cyclic behaviour. Conference Object Antarc* Antarctica Dronning Maud Land Ice Sheet Ice Shelves Alfred Wegener Institute for Polar- and Marine Research (AWI): ePIC (electronic Publication Information Center) Dronning Maud Land Riiser-Larsen ENVELOPE(50.667,50.667,-66.783,-66.783) Weertman ENVELOPE(-67.753,-67.753,-66.972,-66.972) Veststraumen ENVELOPE(-13.000,-13.000,-74.000,-74.000) Plogbreen ENVELOPE(-13.583,-13.583,-73.167,-73.167) |
institution |
Open Polar |
collection |
Alfred Wegener Institute for Polar- and Marine Research (AWI): ePIC (electronic Publication Information Center) |
op_collection_id |
ftawi |
language |
unknown |
description |
At the base of a thick ice sheet the temperature locally reaches the pressure melting point and melting generates a thin subglacial water layer. The basal water lubricates the base and thus enhances the sliding of the ice sheet. As a consequence of sliding, the heat source of internal strain heating decreases and the basal ice cools down over time. When frictional heat and heat advection do not counterbalance this, the ice will become frozen to the bedrock again. In addition, strain heating within a temperate ice layer generates a liquid water fraction in the ice, leading to a softer material and enhanced deformation. If the horizontal or vertical advection of cold ice to the base is weak, this positive feedback will lead to a local creep instability. The effect of basal water is thus twofold: it affects the sliding, as well as the rheology and via both ways the ice dynamics. Subglacial water is therefore a crucial component in the dynamic evolution of ice sheets. We present numerical simulations of the present day ice flow using the three-dimensional thermo-coupled full- Stokes model TIM FD 3 on a 2.5 km horizontal grid in the area of the western Dronning Maud Land, Antarc- tica, including the three ice streams Stancomb-Wills, Veststraumen and Plogbreen and the adjacent Brunt and Riiser- Larsen ice shelves. Three different flux routing algorithms for the subglacial meltwater and a modified Weertman-type sliding relation were implemented in the model to account for higher sliding velocities under wet basal conditions. Subsequent to spin-up simulations different sliding simulations considering wet and dry basal conditions were performed. The simulations show a cyclic behaviour on millennial time scale at distinct locations in the model domain. We estimate the distribution of subglacial water based on different flux routing methods and the effect on the ice flow and the basal thermal regime. We further present our analysis of the involved feedback mechanism between ice flow, temperature and rheology, that are related to the simulated cyclic behaviour. |
format |
Conference Object |
author |
Kleiner, Thomas Humbert, Angelika |
spellingShingle |
Kleiner, Thomas Humbert, Angelika Cyclic behaviour on millennial time scale due to creep instabilities in western Dronning Maud Land, Antarctica |
author_facet |
Kleiner, Thomas Humbert, Angelika |
author_sort |
Kleiner, Thomas |
title |
Cyclic behaviour on millennial time scale due to creep instabilities in western Dronning Maud Land, Antarctica |
title_short |
Cyclic behaviour on millennial time scale due to creep instabilities in western Dronning Maud Land, Antarctica |
title_full |
Cyclic behaviour on millennial time scale due to creep instabilities in western Dronning Maud Land, Antarctica |
title_fullStr |
Cyclic behaviour on millennial time scale due to creep instabilities in western Dronning Maud Land, Antarctica |
title_full_unstemmed |
Cyclic behaviour on millennial time scale due to creep instabilities in western Dronning Maud Land, Antarctica |
title_sort |
cyclic behaviour on millennial time scale due to creep instabilities in western dronning maud land, antarctica |
publisher |
Geophysical Research Abstracts |
publishDate |
2013 |
url |
https://epic.awi.de/id/eprint/32911/ https://epic.awi.de/id/eprint/32911/1/EGU2013-9732.pdf https://hdl.handle.net/10013/epic.41449 https://hdl.handle.net/10013/epic.41449.d001 |
long_lat |
ENVELOPE(50.667,50.667,-66.783,-66.783) ENVELOPE(-67.753,-67.753,-66.972,-66.972) ENVELOPE(-13.000,-13.000,-74.000,-74.000) ENVELOPE(-13.583,-13.583,-73.167,-73.167) |
geographic |
Dronning Maud Land Riiser-Larsen Weertman Veststraumen Plogbreen |
geographic_facet |
Dronning Maud Land Riiser-Larsen Weertman Veststraumen Plogbreen |
genre |
Antarc* Antarctica Dronning Maud Land Ice Sheet Ice Shelves |
genre_facet |
Antarc* Antarctica Dronning Maud Land Ice Sheet Ice Shelves |
op_source |
EPIC3EGU General Assembly, Vienna, 2013-04-07-2013-04-12Vol. 15, EGU2013-9732, Geophysical Research Abstracts |
op_relation |
https://epic.awi.de/id/eprint/32911/1/EGU2013-9732.pdf https://hdl.handle.net/10013/epic.41449.d001 Kleiner, T. orcid:0000-0001-7825-5765 and Humbert, A. (2013) Cyclic behaviour on millennial time scale due to creep instabilities in western Dronning Maud Land, Antarctica , EGU General Assembly, Vienna, 7 April 2013 - 12 April 2013 . hdl:10013/epic.41449 |
_version_ |
1766133460341096448 |