Improved parameterization of marine ice dynamics and flow instabilities for simulation of the Austfonna ice cap using a large-scale ice sheet model Title,Eos Trans.
The Austfonna ice cap covers an area of 8120 km2 and is by far the largest glacier on Svalbard. Almost 30% of the entire area is grounded below sea-level, while the figure is as large as 57% for the known surge-type basins in particular. Marine ice dynamics, as well as flow instabilities presumably...
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ftunivpmadrid:oai:oa.upm.es:5616 2023-06-11T04:10:23+02:00 Improved parameterization of marine ice dynamics and flow instabilities for simulation of the Austfonna ice cap using a large-scale ice sheet model Title,Eos Trans. Dunse, Thorben Greve, Ralf Schuler, Thomas V. Hagen, Jon Ove Navarro Valero, Francisco José Vasilenko, Evgeniy Reijmer, Carleen 2009-12 application/pdf https://oa.upm.es/5616/ eng eng E.T.S.I. Telecomunicación (UPM) http://www.agu.org/meetings/fm09/ https://oa.upm.es/5616/ https://creativecommons.org/licenses/by-nc-nd/3.0/es/ info:eu-repo/semantics/openAccess Proceedings of American Geophysical Union, Fall Meeting 2009 | American Geophysical Union, Fall Meeting 2009 | 14/12/2009 - 18/12/2009 | San Francisco, California, EEUU Medio Ambiente Física info:eu-repo/semantics/conferenceObject Ponencia en Congreso o Jornada PeerReviewed 2009 ftunivpmadrid 2023-04-18T23:15:39Z The Austfonna ice cap covers an area of 8120 km2 and is by far the largest glacier on Svalbard. Almost 30% of the entire area is grounded below sea-level, while the figure is as large as 57% for the known surge-type basins in particular. Marine ice dynamics, as well as flow instabilities presumably control flow regime, form and evolution of Austfonna. These issues are our focus in numerical simulations of the ice cap. We employ the thermodynamic, large-scale ice sheet model SICOPOLIS (http://sicopolis.greveweb.net/) which is based on the shallow-ice approximation. We present improved parameterizations of (a) the marine extent and calving and (b) processes that may initiate flow instabilities such as switches from cold to temperate basal conditions, surface steepening and hence, increases in driving stress, enhanced sliding or deformation of unconsolidated marine sediments and diminishing ice thicknesses towards flotation thickness. Space-borne interferometric snapshots of Austfonna revealed a velocity structure of a slow moving polar ice cap (menos que 10m/a) interrupted by distinct fast flow units with velocities in excess of 100m/a. However, observations of flow variability are scarce. In spring 2008, we established a series of stakes along the centrelines of two fast-flowing units. Repeated DGPS and continuous GPS measurements of the stake positions give insight in the temporal flow variability of these units and provide constrains to the modeled surface velocity field. Austfonna¿s thermal structure is described as polythermal. However, direct measurements of the temperature distribution is available only from one single borehole at the summit area. The vertical temperature profile shows that the bulk of the 567m thick ice column is cold, only underlain by a thin temperate basal layer of approximately 20m. To acquire a spatially extended picture of the thermal structure (and bed topography), we used low-frequency (20 MHz) GPR profiling across the ice cap and the particular flow units. The measurements ... Conference Object Austfonna glacier Ice cap Ice Sheet Polar Ice Cap Svalbard Archivo Digital UPM (Universidad Politécnica de Madrid) Svalbard Austfonna ENVELOPE(24.559,24.559,79.835,79.835) |
institution |
Open Polar |
collection |
Archivo Digital UPM (Universidad Politécnica de Madrid) |
op_collection_id |
ftunivpmadrid |
language |
English |
topic |
Medio Ambiente Física |
spellingShingle |
Medio Ambiente Física Dunse, Thorben Greve, Ralf Schuler, Thomas V. Hagen, Jon Ove Navarro Valero, Francisco José Vasilenko, Evgeniy Reijmer, Carleen Improved parameterization of marine ice dynamics and flow instabilities for simulation of the Austfonna ice cap using a large-scale ice sheet model Title,Eos Trans. |
topic_facet |
Medio Ambiente Física |
description |
The Austfonna ice cap covers an area of 8120 km2 and is by far the largest glacier on Svalbard. Almost 30% of the entire area is grounded below sea-level, while the figure is as large as 57% for the known surge-type basins in particular. Marine ice dynamics, as well as flow instabilities presumably control flow regime, form and evolution of Austfonna. These issues are our focus in numerical simulations of the ice cap. We employ the thermodynamic, large-scale ice sheet model SICOPOLIS (http://sicopolis.greveweb.net/) which is based on the shallow-ice approximation. We present improved parameterizations of (a) the marine extent and calving and (b) processes that may initiate flow instabilities such as switches from cold to temperate basal conditions, surface steepening and hence, increases in driving stress, enhanced sliding or deformation of unconsolidated marine sediments and diminishing ice thicknesses towards flotation thickness. Space-borne interferometric snapshots of Austfonna revealed a velocity structure of a slow moving polar ice cap (menos que 10m/a) interrupted by distinct fast flow units with velocities in excess of 100m/a. However, observations of flow variability are scarce. In spring 2008, we established a series of stakes along the centrelines of two fast-flowing units. Repeated DGPS and continuous GPS measurements of the stake positions give insight in the temporal flow variability of these units and provide constrains to the modeled surface velocity field. Austfonna¿s thermal structure is described as polythermal. However, direct measurements of the temperature distribution is available only from one single borehole at the summit area. The vertical temperature profile shows that the bulk of the 567m thick ice column is cold, only underlain by a thin temperate basal layer of approximately 20m. To acquire a spatially extended picture of the thermal structure (and bed topography), we used low-frequency (20 MHz) GPR profiling across the ice cap and the particular flow units. The measurements ... |
format |
Conference Object |
author |
Dunse, Thorben Greve, Ralf Schuler, Thomas V. Hagen, Jon Ove Navarro Valero, Francisco José Vasilenko, Evgeniy Reijmer, Carleen |
author_facet |
Dunse, Thorben Greve, Ralf Schuler, Thomas V. Hagen, Jon Ove Navarro Valero, Francisco José Vasilenko, Evgeniy Reijmer, Carleen |
author_sort |
Dunse, Thorben |
title |
Improved parameterization of marine ice dynamics and flow instabilities for simulation of the Austfonna ice cap using a large-scale ice sheet model Title,Eos Trans. |
title_short |
Improved parameterization of marine ice dynamics and flow instabilities for simulation of the Austfonna ice cap using a large-scale ice sheet model Title,Eos Trans. |
title_full |
Improved parameterization of marine ice dynamics and flow instabilities for simulation of the Austfonna ice cap using a large-scale ice sheet model Title,Eos Trans. |
title_fullStr |
Improved parameterization of marine ice dynamics and flow instabilities for simulation of the Austfonna ice cap using a large-scale ice sheet model Title,Eos Trans. |
title_full_unstemmed |
Improved parameterization of marine ice dynamics and flow instabilities for simulation of the Austfonna ice cap using a large-scale ice sheet model Title,Eos Trans. |
title_sort |
improved parameterization of marine ice dynamics and flow instabilities for simulation of the austfonna ice cap using a large-scale ice sheet model title,eos trans. |
publisher |
E.T.S.I. Telecomunicación (UPM) |
publishDate |
2009 |
url |
https://oa.upm.es/5616/ |
long_lat |
ENVELOPE(24.559,24.559,79.835,79.835) |
geographic |
Svalbard Austfonna |
geographic_facet |
Svalbard Austfonna |
genre |
Austfonna glacier Ice cap Ice Sheet Polar Ice Cap Svalbard |
genre_facet |
Austfonna glacier Ice cap Ice Sheet Polar Ice Cap Svalbard |
op_source |
Proceedings of American Geophysical Union, Fall Meeting 2009 | American Geophysical Union, Fall Meeting 2009 | 14/12/2009 - 18/12/2009 | San Francisco, California, EEUU |
op_relation |
http://www.agu.org/meetings/fm09/ https://oa.upm.es/5616/ |
op_rights |
https://creativecommons.org/licenses/by-nc-nd/3.0/es/ info:eu-repo/semantics/openAccess |
_version_ |
1768384746453204992 |