The topology of ice-sheet centres
Abstract An ice sheet will, in general, possess points where the horizontal component of velocity is zero, and some of these will be ice centres, occurring close to summits. The paper examines the possible flow patterns near such points. The corresponding horizontal strain-rate pattern is studied by...
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Cambridge University Press (CUP)
1991
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Online Access: | http://dx.doi.org/10.1017/s0022143000007231 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000007231 |
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crcambridgeupr:10.1017/s0022143000007231 2024-03-03T08:45:24+00:00 The topology of ice-sheet centres Nye, J.F. 1991 http://dx.doi.org/10.1017/s0022143000007231 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000007231 en eng Cambridge University Press (CUP) Journal of Glaciology volume 37, issue 126, page 220-227 ISSN 0022-1430 1727-5652 Earth-Surface Processes journal-article 1991 crcambridgeupr https://doi.org/10.1017/s0022143000007231 2024-02-08T08:36:10Z Abstract An ice sheet will, in general, possess points where the horizontal component of velocity is zero, and some of these will be ice centres, occurring close to summits. The paper examines the possible flow patterns near such points. The corresponding horizontal strain-rate pattern is studied by considering an ice sheet which initially has perfect circular symmetry about a vertical axis. Before perturbation there is an isotropic point for the horizontal surface strain rate at the centre. It may be shown, on purely topological grounds and without any reference to the mechanism of flow, that, when the symmetry is broken, this point, being degenerate and structurally unstable, breaks up into two structurally stable components. The breakup always occurs in essentially the same way. Around the two component points the trajectories of principal strain-rate directions always have the lemon pattern. The contours of equal principal strain rate around them are usually hyperbolic; however, if the unperturbed flow pattern had a very pronounced spiral character, they would be elliptic. This behaviour is in contrast to that of the ice centre itself, which remains unsplit. Article in Journal/Newspaper Ice Sheet Journal of Glaciology Cambridge University Press Journal of Glaciology 37 126 220 227 |
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Open Polar |
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Cambridge University Press |
op_collection_id |
crcambridgeupr |
language |
English |
topic |
Earth-Surface Processes |
spellingShingle |
Earth-Surface Processes Nye, J.F. The topology of ice-sheet centres |
topic_facet |
Earth-Surface Processes |
description |
Abstract An ice sheet will, in general, possess points where the horizontal component of velocity is zero, and some of these will be ice centres, occurring close to summits. The paper examines the possible flow patterns near such points. The corresponding horizontal strain-rate pattern is studied by considering an ice sheet which initially has perfect circular symmetry about a vertical axis. Before perturbation there is an isotropic point for the horizontal surface strain rate at the centre. It may be shown, on purely topological grounds and without any reference to the mechanism of flow, that, when the symmetry is broken, this point, being degenerate and structurally unstable, breaks up into two structurally stable components. The breakup always occurs in essentially the same way. Around the two component points the trajectories of principal strain-rate directions always have the lemon pattern. The contours of equal principal strain rate around them are usually hyperbolic; however, if the unperturbed flow pattern had a very pronounced spiral character, they would be elliptic. This behaviour is in contrast to that of the ice centre itself, which remains unsplit. |
format |
Article in Journal/Newspaper |
author |
Nye, J.F. |
author_facet |
Nye, J.F. |
author_sort |
Nye, J.F. |
title |
The topology of ice-sheet centres |
title_short |
The topology of ice-sheet centres |
title_full |
The topology of ice-sheet centres |
title_fullStr |
The topology of ice-sheet centres |
title_full_unstemmed |
The topology of ice-sheet centres |
title_sort |
topology of ice-sheet centres |
publisher |
Cambridge University Press (CUP) |
publishDate |
1991 |
url |
http://dx.doi.org/10.1017/s0022143000007231 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000007231 |
genre |
Ice Sheet Journal of Glaciology |
genre_facet |
Ice Sheet Journal of Glaciology |
op_source |
Journal of Glaciology volume 37, issue 126, page 220-227 ISSN 0022-1430 1727-5652 |
op_doi |
https://doi.org/10.1017/s0022143000007231 |
container_title |
Journal of Glaciology |
container_volume |
37 |
container_issue |
126 |
container_start_page |
220 |
op_container_end_page |
227 |
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1792500953347260416 |