Influence of anisotropy on velocity and age distribution at Scharffenbergbotnen blue ice area
We use a full-Stokes thermo-mechanically coupled ice-flow model to study the dynamics of the glacier inside Scharffenbergbotnen valley, Dronning Maud Land, Antarctica. The domain encompasses a high accumulation rate region and, downstream, a sublimation-dominated bare ice ablation area. The ablation...
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Uppsala universitet, Luft-, vatten- och landskapslära
2014
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ftuppsalauniv:oai:DiVA.org:uu-227143 2023-05-15T14:00:26+02:00 Influence of anisotropy on velocity and age distribution at Scharffenbergbotnen blue ice area Zwinger, T. Schaefer, M. Martin, C. Moore, John C. 2014 application/pdf http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-227143 https://doi.org/10.5194/tc-8-607-2014 eng eng Uppsala universitet, Luft-, vatten- och landskapslära The Cryosphere, 1994-0416, 2014, 8:2, s. 607-621 http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-227143 doi:10.5194/tc-8-607-2014 ISI:000335377200019 info:eu-repo/semantics/openAccess Physical Geography Naturgeografi Article in journal info:eu-repo/semantics/article text 2014 ftuppsalauniv https://doi.org/10.5194/tc-8-607-2014 2023-02-23T21:52:07Z We use a full-Stokes thermo-mechanically coupled ice-flow model to study the dynamics of the glacier inside Scharffenbergbotnen valley, Dronning Maud Land, Antarctica. The domain encompasses a high accumulation rate region and, downstream, a sublimation-dominated bare ice ablation area. The ablation ice area is notable for having old ice at its surface since the vertical velocity is upwards, and horizontal velocities are almost stagnant there. We compare the model simulation with field observations of velocities and the age distribution of the surface ice. No satisfactory match using an isotropic flow law could be found because of too high vertical velocities and much too high horizontal ones in simulations despite varying enhancement factor, geothermal heat flux and surface temperatures over large ranges. However, the existence of a pronounced ice fabric may explain the observed present-day surface velocity and mass balance distribution in the inner Scharffenbergbotnen blue ice area. Near absence of data on the temporal evolution of Scharffenbergbotnen since the Late Glacial Maximum necessitates exploration of the impact of anisotropy using prescribed ice fabrics: isotropic, single maximum, and linear variation with depth, in both two-dimensional and three-dimensional flow models. The realistic velocity field simulated with a noncollinear orthotropic flow law, however, produced surface ages in significant disagreement with the few reliable age measurements and suggests that the age field is not in a steady state and that the present distribution is a result of a flow reorganization at about 15 000 yr BP. In order to fully understand the surface age distribution, a transient simulation starting from the Late Glacial Maximum including the correct initial conditions for geometry, age, fabric and temperature distribution would be needed. This is the first time that the importance of anisotropy has been demonstrated in the ice dynamics of a blue ice area and demonstrates the need to understand ice flow in order to ... Article in Journal/Newspaper Antarc* Antarctica Dronning Maud Land The Cryosphere Uppsala University: Publications (DiVA) Dronning Maud Land Scharffenbergbotnen ENVELOPE(-11.092,-11.092,-74.575,-74.575) The Cryosphere 8 2 607 621 |
institution |
Open Polar |
collection |
Uppsala University: Publications (DiVA) |
op_collection_id |
ftuppsalauniv |
language |
English |
topic |
Physical Geography Naturgeografi |
spellingShingle |
Physical Geography Naturgeografi Zwinger, T. Schaefer, M. Martin, C. Moore, John C. Influence of anisotropy on velocity and age distribution at Scharffenbergbotnen blue ice area |
topic_facet |
Physical Geography Naturgeografi |
description |
We use a full-Stokes thermo-mechanically coupled ice-flow model to study the dynamics of the glacier inside Scharffenbergbotnen valley, Dronning Maud Land, Antarctica. The domain encompasses a high accumulation rate region and, downstream, a sublimation-dominated bare ice ablation area. The ablation ice area is notable for having old ice at its surface since the vertical velocity is upwards, and horizontal velocities are almost stagnant there. We compare the model simulation with field observations of velocities and the age distribution of the surface ice. No satisfactory match using an isotropic flow law could be found because of too high vertical velocities and much too high horizontal ones in simulations despite varying enhancement factor, geothermal heat flux and surface temperatures over large ranges. However, the existence of a pronounced ice fabric may explain the observed present-day surface velocity and mass balance distribution in the inner Scharffenbergbotnen blue ice area. Near absence of data on the temporal evolution of Scharffenbergbotnen since the Late Glacial Maximum necessitates exploration of the impact of anisotropy using prescribed ice fabrics: isotropic, single maximum, and linear variation with depth, in both two-dimensional and three-dimensional flow models. The realistic velocity field simulated with a noncollinear orthotropic flow law, however, produced surface ages in significant disagreement with the few reliable age measurements and suggests that the age field is not in a steady state and that the present distribution is a result of a flow reorganization at about 15 000 yr BP. In order to fully understand the surface age distribution, a transient simulation starting from the Late Glacial Maximum including the correct initial conditions for geometry, age, fabric and temperature distribution would be needed. This is the first time that the importance of anisotropy has been demonstrated in the ice dynamics of a blue ice area and demonstrates the need to understand ice flow in order to ... |
format |
Article in Journal/Newspaper |
author |
Zwinger, T. Schaefer, M. Martin, C. Moore, John C. |
author_facet |
Zwinger, T. Schaefer, M. Martin, C. Moore, John C. |
author_sort |
Zwinger, T. |
title |
Influence of anisotropy on velocity and age distribution at Scharffenbergbotnen blue ice area |
title_short |
Influence of anisotropy on velocity and age distribution at Scharffenbergbotnen blue ice area |
title_full |
Influence of anisotropy on velocity and age distribution at Scharffenbergbotnen blue ice area |
title_fullStr |
Influence of anisotropy on velocity and age distribution at Scharffenbergbotnen blue ice area |
title_full_unstemmed |
Influence of anisotropy on velocity and age distribution at Scharffenbergbotnen blue ice area |
title_sort |
influence of anisotropy on velocity and age distribution at scharffenbergbotnen blue ice area |
publisher |
Uppsala universitet, Luft-, vatten- och landskapslära |
publishDate |
2014 |
url |
http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-227143 https://doi.org/10.5194/tc-8-607-2014 |
long_lat |
ENVELOPE(-11.092,-11.092,-74.575,-74.575) |
geographic |
Dronning Maud Land Scharffenbergbotnen |
geographic_facet |
Dronning Maud Land Scharffenbergbotnen |
genre |
Antarc* Antarctica Dronning Maud Land The Cryosphere |
genre_facet |
Antarc* Antarctica Dronning Maud Land The Cryosphere |
op_relation |
The Cryosphere, 1994-0416, 2014, 8:2, s. 607-621 http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-227143 doi:10.5194/tc-8-607-2014 ISI:000335377200019 |
op_rights |
info:eu-repo/semantics/openAccess |
op_doi |
https://doi.org/10.5194/tc-8-607-2014 |
container_title |
The Cryosphere |
container_volume |
8 |
container_issue |
2 |
container_start_page |
607 |
op_container_end_page |
621 |
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1766269526878453760 |