Assessment of heat sources on the control of fast flow of Vestfonna ice cap, Svalbard
Understanding the response of fast flowing ice streams or outlet glaciers to changing climate is crucial in order to make reliable projections of sea level change over the coming decades. Motion of fast outlet glaciers occurs largely through basal motion governed by physical processes at the glacier...
Published in: | The Cryosphere |
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Format: | Article in Journal/Newspaper |
Language: | English |
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Copernicus Publications
2014
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Online Access: | https://doi.org/10.5194/tc-8-1951-2014 http://www.the-cryosphere.net/8/1951/2014/tc-8-1951-2014.pdf https://doaj.org/article/2e5f750d8fd84dcea776606fecb159dc |
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fttriple:oai:gotriple.eu:oai:doaj.org/article:2e5f750d8fd84dcea776606fecb159dc 2023-05-15T16:22:17+02:00 Assessment of heat sources on the control of fast flow of Vestfonna ice cap, Svalbard M. Schäfer F. Gillet-Chaulet R. Gladstone R. Pettersson V. A. Pohjola T. Strozzi T. Zwinger 2014-10-01 https://doi.org/10.5194/tc-8-1951-2014 http://www.the-cryosphere.net/8/1951/2014/tc-8-1951-2014.pdf https://doaj.org/article/2e5f750d8fd84dcea776606fecb159dc en eng Copernicus Publications 1994-0416 1994-0424 doi:10.5194/tc-8-1951-2014 http://www.the-cryosphere.net/8/1951/2014/tc-8-1951-2014.pdf https://doaj.org/article/2e5f750d8fd84dcea776606fecb159dc undefined The Cryosphere, Vol 8, Iss 5, Pp 1951-1973 (2014) envir geo Journal Article https://vocabularies.coar-repositories.org/resource_types/c_6501/ 2014 fttriple https://doi.org/10.5194/tc-8-1951-2014 2023-01-22T19:34:14Z Understanding the response of fast flowing ice streams or outlet glaciers to changing climate is crucial in order to make reliable projections of sea level change over the coming decades. Motion of fast outlet glaciers occurs largely through basal motion governed by physical processes at the glacier bed, which are not yet fully understood. Various subglacial mechanisms have been suggested for fast flow but common to most of the suggested processes is the requirement of presence of liquid water, and thus temperate conditions. We use a combination of modelling, field, and remote observations in order to study links between different heat sources, the thermal regime and basal sliding in fast flowing areas on Vestfonna ice cap. A special emphasis lies on Franklinbreen, a fast flowing outlet glacier which has been observed to accelerate recently. We use the ice flow model Elmer/Ice including a Weertman type sliding law and a Robin inverse method to infer basal friction parameters from observed surface velocities. Firn heating, i.e. latent heat release through percolation of melt water, is included in our model; its parameterisation is calibrated with the temperature record of a deep borehole. We found that strain heating is negligible, whereas friction heating is identified as one possible trigger for the onset of fast flow. Firn heating is a significant heat source in the central thick and slow flowing area of the ice cap and the essential driver behind the ongoing fast flow in all outlets. Our findings suggest a possible scenario of the onset and maintenance of fast flow on the Vestfonna ice cap based on thermal processes and emphasise the role of latent heat released through refreezing of percolating melt water for fast flow. However, these processes cannot yet be captured in a temporally evolving sliding law. In order to simulate correctly fast flowing outlet glaciers, ice flow models not only need to account fully for all heat sources, but also need to incorporate a sliding law that is not solely based on the ... Article in Journal/Newspaper glacier Ice cap Svalbard The Cryosphere Vestfonna Unknown Svalbard Vestfonna ENVELOPE(20.761,20.761,79.941,79.941) Weertman ENVELOPE(-67.753,-67.753,-66.972,-66.972) The Cryosphere 8 5 1951 1973 |
institution |
Open Polar |
collection |
Unknown |
op_collection_id |
fttriple |
language |
English |
topic |
envir geo |
spellingShingle |
envir geo M. Schäfer F. Gillet-Chaulet R. Gladstone R. Pettersson V. A. Pohjola T. Strozzi T. Zwinger Assessment of heat sources on the control of fast flow of Vestfonna ice cap, Svalbard |
topic_facet |
envir geo |
description |
Understanding the response of fast flowing ice streams or outlet glaciers to changing climate is crucial in order to make reliable projections of sea level change over the coming decades. Motion of fast outlet glaciers occurs largely through basal motion governed by physical processes at the glacier bed, which are not yet fully understood. Various subglacial mechanisms have been suggested for fast flow but common to most of the suggested processes is the requirement of presence of liquid water, and thus temperate conditions. We use a combination of modelling, field, and remote observations in order to study links between different heat sources, the thermal regime and basal sliding in fast flowing areas on Vestfonna ice cap. A special emphasis lies on Franklinbreen, a fast flowing outlet glacier which has been observed to accelerate recently. We use the ice flow model Elmer/Ice including a Weertman type sliding law and a Robin inverse method to infer basal friction parameters from observed surface velocities. Firn heating, i.e. latent heat release through percolation of melt water, is included in our model; its parameterisation is calibrated with the temperature record of a deep borehole. We found that strain heating is negligible, whereas friction heating is identified as one possible trigger for the onset of fast flow. Firn heating is a significant heat source in the central thick and slow flowing area of the ice cap and the essential driver behind the ongoing fast flow in all outlets. Our findings suggest a possible scenario of the onset and maintenance of fast flow on the Vestfonna ice cap based on thermal processes and emphasise the role of latent heat released through refreezing of percolating melt water for fast flow. However, these processes cannot yet be captured in a temporally evolving sliding law. In order to simulate correctly fast flowing outlet glaciers, ice flow models not only need to account fully for all heat sources, but also need to incorporate a sliding law that is not solely based on the ... |
format |
Article in Journal/Newspaper |
author |
M. Schäfer F. Gillet-Chaulet R. Gladstone R. Pettersson V. A. Pohjola T. Strozzi T. Zwinger |
author_facet |
M. Schäfer F. Gillet-Chaulet R. Gladstone R. Pettersson V. A. Pohjola T. Strozzi T. Zwinger |
author_sort |
M. Schäfer |
title |
Assessment of heat sources on the control of fast flow of Vestfonna ice cap, Svalbard |
title_short |
Assessment of heat sources on the control of fast flow of Vestfonna ice cap, Svalbard |
title_full |
Assessment of heat sources on the control of fast flow of Vestfonna ice cap, Svalbard |
title_fullStr |
Assessment of heat sources on the control of fast flow of Vestfonna ice cap, Svalbard |
title_full_unstemmed |
Assessment of heat sources on the control of fast flow of Vestfonna ice cap, Svalbard |
title_sort |
assessment of heat sources on the control of fast flow of vestfonna ice cap, svalbard |
publisher |
Copernicus Publications |
publishDate |
2014 |
url |
https://doi.org/10.5194/tc-8-1951-2014 http://www.the-cryosphere.net/8/1951/2014/tc-8-1951-2014.pdf https://doaj.org/article/2e5f750d8fd84dcea776606fecb159dc |
long_lat |
ENVELOPE(20.761,20.761,79.941,79.941) ENVELOPE(-67.753,-67.753,-66.972,-66.972) |
geographic |
Svalbard Vestfonna Weertman |
geographic_facet |
Svalbard Vestfonna Weertman |
genre |
glacier Ice cap Svalbard The Cryosphere Vestfonna |
genre_facet |
glacier Ice cap Svalbard The Cryosphere Vestfonna |
op_source |
The Cryosphere, Vol 8, Iss 5, Pp 1951-1973 (2014) |
op_relation |
1994-0416 1994-0424 doi:10.5194/tc-8-1951-2014 http://www.the-cryosphere.net/8/1951/2014/tc-8-1951-2014.pdf https://doaj.org/article/2e5f750d8fd84dcea776606fecb159dc |
op_rights |
undefined |
op_doi |
https://doi.org/10.5194/tc-8-1951-2014 |
container_title |
The Cryosphere |
container_volume |
8 |
container_issue |
5 |
container_start_page |
1951 |
op_container_end_page |
1973 |
_version_ |
1766010251420631040 |