A three-dimensional numerical model of the confluence area of Unteraargletscher, Bernese Alps, Switzerland
Abstract With the use of a numerical three-dimensional (3-D) model the flow dynamics of the confluence area of Unteraargletscher, Bernese Alps, Switzerland, are studied. Previous predictions, based on conceptual two-dimensional models, about flow characteristics at confluence areas are tested agains...
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Cambridge University Press (CUP)
1999
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Online Access: | http://dx.doi.org/10.1017/s0022143000001726 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000001726 |
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crcambridgeupr:10.1017/s0022143000001726 2024-09-15T18:15:39+00:00 A three-dimensional numerical model of the confluence area of Unteraargletscher, Bernese Alps, Switzerland Gudmundsson, G. Hilmar 1999 http://dx.doi.org/10.1017/s0022143000001726 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000001726 en eng Cambridge University Press (CUP) Journal of Glaciology volume 45, issue 150, page 219-230 ISSN 0022-1430 1727-5652 journal-article 1999 crcambridgeupr https://doi.org/10.1017/s0022143000001726 2024-07-24T04:03:23Z Abstract With the use of a numerical three-dimensional (3-D) model the flow dynamics of the confluence area of Unteraargletscher, Bernese Alps, Switzerland, are studied. Previous predictions, based on conceptual two-dimensional models, about flow characteristics at confluence areas are tested against results from the fully 3-D model. Measured winter velocities are used for model verification. Despite some consistent systematic differences, good overall agreement between measured and calculated surface velocities is obtained. The calculated vertical strain-rate variation with depth is in good agreement with available measurements from boreholes. The ice is found to be almost three times stiffer than standard estimates of rheological parameters for glacier ice would predict. The model predicts a complicated yet realistic pattern of vertical velocity variation along the surface. The most noticeable features of the vertical velocity distribution across the surface are listed, and their relation to topographic surface undulations and the overall dynamics of the confluence discussed. In accordance with previous results from analytical models, a strongly localized surface trough and a concomitant negative (downward orientation) vertical velocity anomaly develop at the junction point. Although depth-integrated strain rates are positive (extension), the basal layer is compressed vertically. The ice-cored medial moraine is formed by differential ablation. The flow mechanics of the confluence area play only an indirect role, by enabling transfer of debris-covered marginal ice towards the confluence center. In the absence of differential ablation, an elongated surface depression would be formed in the down-glacier direction from the junction point instead of an elevated ice-cored medial moraine. Article in Journal/Newspaper Journal of Glaciology Cambridge University Press Journal of Glaciology 45 150 219 230 |
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Open Polar |
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Cambridge University Press |
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crcambridgeupr |
language |
English |
description |
Abstract With the use of a numerical three-dimensional (3-D) model the flow dynamics of the confluence area of Unteraargletscher, Bernese Alps, Switzerland, are studied. Previous predictions, based on conceptual two-dimensional models, about flow characteristics at confluence areas are tested against results from the fully 3-D model. Measured winter velocities are used for model verification. Despite some consistent systematic differences, good overall agreement between measured and calculated surface velocities is obtained. The calculated vertical strain-rate variation with depth is in good agreement with available measurements from boreholes. The ice is found to be almost three times stiffer than standard estimates of rheological parameters for glacier ice would predict. The model predicts a complicated yet realistic pattern of vertical velocity variation along the surface. The most noticeable features of the vertical velocity distribution across the surface are listed, and their relation to topographic surface undulations and the overall dynamics of the confluence discussed. In accordance with previous results from analytical models, a strongly localized surface trough and a concomitant negative (downward orientation) vertical velocity anomaly develop at the junction point. Although depth-integrated strain rates are positive (extension), the basal layer is compressed vertically. The ice-cored medial moraine is formed by differential ablation. The flow mechanics of the confluence area play only an indirect role, by enabling transfer of debris-covered marginal ice towards the confluence center. In the absence of differential ablation, an elongated surface depression would be formed in the down-glacier direction from the junction point instead of an elevated ice-cored medial moraine. |
format |
Article in Journal/Newspaper |
author |
Gudmundsson, G. Hilmar |
spellingShingle |
Gudmundsson, G. Hilmar A three-dimensional numerical model of the confluence area of Unteraargletscher, Bernese Alps, Switzerland |
author_facet |
Gudmundsson, G. Hilmar |
author_sort |
Gudmundsson, G. Hilmar |
title |
A three-dimensional numerical model of the confluence area of Unteraargletscher, Bernese Alps, Switzerland |
title_short |
A three-dimensional numerical model of the confluence area of Unteraargletscher, Bernese Alps, Switzerland |
title_full |
A three-dimensional numerical model of the confluence area of Unteraargletscher, Bernese Alps, Switzerland |
title_fullStr |
A three-dimensional numerical model of the confluence area of Unteraargletscher, Bernese Alps, Switzerland |
title_full_unstemmed |
A three-dimensional numerical model of the confluence area of Unteraargletscher, Bernese Alps, Switzerland |
title_sort |
three-dimensional numerical model of the confluence area of unteraargletscher, bernese alps, switzerland |
publisher |
Cambridge University Press (CUP) |
publishDate |
1999 |
url |
http://dx.doi.org/10.1017/s0022143000001726 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000001726 |
genre |
Journal of Glaciology |
genre_facet |
Journal of Glaciology |
op_source |
Journal of Glaciology volume 45, issue 150, page 219-230 ISSN 0022-1430 1727-5652 |
op_doi |
https://doi.org/10.1017/s0022143000001726 |
container_title |
Journal of Glaciology |
container_volume |
45 |
container_issue |
150 |
container_start_page |
219 |
op_container_end_page |
230 |
_version_ |
1810453553307713536 |