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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Copernicus Publications
2014
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ftnonlinearchiv:oai:noa.gwlb.de:cop_mods_00020266 2023-05-15T13:41:02+02:00 Influence of anisotropy on velocity and age distribution at Scharffenbergbotnen blue ice area Zwinger, T. Schäfer, M. Martín, C. Moore, J. C. 2014-04 electronic https://doi.org/10.5194/tc-8-607-2014 https://noa.gwlb.de/receive/cop_mods_00020266 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00020221/tc-8-607-2014.pdf https://tc.copernicus.org/articles/8/607/2014/tc-8-607-2014.pdf eng eng Copernicus Publications The Cryosphere -- ˜Theœ Cryosphere -- http://www.bibliothek.uni-regensburg.de/ezeit/?2393169 -- http://www.the-cryosphere.net/ -- 1994-0424 https://doi.org/10.5194/tc-8-607-2014 https://noa.gwlb.de/receive/cop_mods_00020266 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00020221/tc-8-607-2014.pdf https://tc.copernicus.org/articles/8/607/2014/tc-8-607-2014.pdf uneingeschränkt info:eu-repo/semantics/openAccess article Verlagsveröffentlichung article Text doc-type:article 2014 ftnonlinearchiv https://doi.org/10.5194/tc-8-607-2014 2022-02-08T22:52:15Z 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 better interpret archives of ancient ice for paleoclimate research. Article in Journal/Newspaper Antarc* Antarctica Dronning Maud Land The Cryosphere Niedersächsisches Online-Archiv NOA Dronning Maud Land Scharffenbergbotnen ENVELOPE(-11.092,-11.092,-74.575,-74.575) The Cryosphere 8 2 607 621 |
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Open Polar |
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Niedersächsisches Online-Archiv NOA |
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ftnonlinearchiv |
language |
English |
topic |
article Verlagsveröffentlichung |
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article Verlagsveröffentlichung Zwinger, T. Schäfer, M. Martín, C. Moore, J. C. Influence of anisotropy on velocity and age distribution at Scharffenbergbotnen blue ice area |
topic_facet |
article Verlagsveröffentlichung |
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 better interpret archives of ancient ice for paleoclimate research. |
format |
Article in Journal/Newspaper |
author |
Zwinger, T. Schäfer, M. Martín, C. Moore, J. C. |
author_facet |
Zwinger, T. Schäfer, M. Martín, C. Moore, J. 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 |
Copernicus Publications |
publishDate |
2014 |
url |
https://doi.org/10.5194/tc-8-607-2014 https://noa.gwlb.de/receive/cop_mods_00020266 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00020221/tc-8-607-2014.pdf https://tc.copernicus.org/articles/8/607/2014/tc-8-607-2014.pdf |
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 -- ˜Theœ Cryosphere -- http://www.bibliothek.uni-regensburg.de/ezeit/?2393169 -- http://www.the-cryosphere.net/ -- 1994-0424 https://doi.org/10.5194/tc-8-607-2014 https://noa.gwlb.de/receive/cop_mods_00020266 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00020221/tc-8-607-2014.pdf https://tc.copernicus.org/articles/8/607/2014/tc-8-607-2014.pdf |
op_rights |
uneingeschränkt 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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1766144812431441920 |