Application of a Flow Model to the Ice-divide Region of Devon Island Ice Cap, Canada
Abstract The steady-state flow model of Reeh (1988) is applied to a flow line that starts at the highest point of the Devon Island ice cap, follows the surface crest for 7.6 km, and then runs down the slope for a further 3.7 km. The effects of bedrock undulations, divergence of the flow lines, the v...
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Language: | English |
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Cambridge University Press (CUP)
1988
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Online Access: | http://dx.doi.org/10.1017/s0022143000009060 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000009060 |
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crcambridgeupr:10.1017/s0022143000009060 2024-09-15T18:03:39+00:00 Application of a Flow Model to the Ice-divide Region of Devon Island Ice Cap, Canada Reeh, N. Paterson, W.S.B. 1988 http://dx.doi.org/10.1017/s0022143000009060 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000009060 en eng Cambridge University Press (CUP) Journal of Glaciology volume 34, issue 116, page 55-63 ISSN 0022-1430 1727-5652 journal-article 1988 crcambridgeupr https://doi.org/10.1017/s0022143000009060 2024-08-21T04:04:29Z Abstract The steady-state flow model of Reeh (1988) is applied to a flow line that starts at the highest point of the Devon Island ice cap, follows the surface crest for 7.6 km, and then runs down the slope for a further 3.7 km. The effects of bedrock undulations, divergence of the flow lines, the variation of temperature with depth, and a basal layer of “soft” ice-age ice are taken into account. A flow law with n = 3 and a value of A close to that of Paterson (1981) is used. Longitudinal stress variations are neglected so that shear stress is calculated by the usual formula. It is estimated that these calculated values may be in error by at most 30%. Depth profiles of effective shear stress, and of the components of velocity and normal strain-rate, are presented at selected points along the flow line. These illustrate the large variations that occur near an ice divide and over bedrock undulations of amplitude comparable with the mean ice thickness. The model gives good predictions of the surface profile and of longitudinal and transverse surface strain-rates measured at ten points along the flow line. Predicted depth profiles of horizontal and vertical velocity components are compared with those measured in a bore hole. Comparison is limited by the fact that the model works in ice equivalent, whereas about 20% of the ice column consists of firn with different rheological properties from ice. The vertical velocity prediction is good. However, the model does not reproduce well the shape of the horizontal velocity profile, although measured and calculated fluxes differ only slightly. Predicted annual-layer thicknesses are within 15% of the measured ones in the upper half of the ice column, which consists of ice deposited in the last 1000 years. Predicted thicknesses in older ice are too small and the discrepancy increases with depth. This might indicate increased precipitation or, more likely, a thinner ice cap in the climatic optimum. However, it could also result from the fact that the layer of “soft” ice has ... Article in Journal/Newspaper Devon Island Ice cap Journal of Glaciology Cambridge University Press Journal of Glaciology 34 116 55 63 |
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Open Polar |
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Cambridge University Press |
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crcambridgeupr |
language |
English |
description |
Abstract The steady-state flow model of Reeh (1988) is applied to a flow line that starts at the highest point of the Devon Island ice cap, follows the surface crest for 7.6 km, and then runs down the slope for a further 3.7 km. The effects of bedrock undulations, divergence of the flow lines, the variation of temperature with depth, and a basal layer of “soft” ice-age ice are taken into account. A flow law with n = 3 and a value of A close to that of Paterson (1981) is used. Longitudinal stress variations are neglected so that shear stress is calculated by the usual formula. It is estimated that these calculated values may be in error by at most 30%. Depth profiles of effective shear stress, and of the components of velocity and normal strain-rate, are presented at selected points along the flow line. These illustrate the large variations that occur near an ice divide and over bedrock undulations of amplitude comparable with the mean ice thickness. The model gives good predictions of the surface profile and of longitudinal and transverse surface strain-rates measured at ten points along the flow line. Predicted depth profiles of horizontal and vertical velocity components are compared with those measured in a bore hole. Comparison is limited by the fact that the model works in ice equivalent, whereas about 20% of the ice column consists of firn with different rheological properties from ice. The vertical velocity prediction is good. However, the model does not reproduce well the shape of the horizontal velocity profile, although measured and calculated fluxes differ only slightly. Predicted annual-layer thicknesses are within 15% of the measured ones in the upper half of the ice column, which consists of ice deposited in the last 1000 years. Predicted thicknesses in older ice are too small and the discrepancy increases with depth. This might indicate increased precipitation or, more likely, a thinner ice cap in the climatic optimum. However, it could also result from the fact that the layer of “soft” ice has ... |
format |
Article in Journal/Newspaper |
author |
Reeh, N. Paterson, W.S.B. |
spellingShingle |
Reeh, N. Paterson, W.S.B. Application of a Flow Model to the Ice-divide Region of Devon Island Ice Cap, Canada |
author_facet |
Reeh, N. Paterson, W.S.B. |
author_sort |
Reeh, N. |
title |
Application of a Flow Model to the Ice-divide Region of Devon Island Ice Cap, Canada |
title_short |
Application of a Flow Model to the Ice-divide Region of Devon Island Ice Cap, Canada |
title_full |
Application of a Flow Model to the Ice-divide Region of Devon Island Ice Cap, Canada |
title_fullStr |
Application of a Flow Model to the Ice-divide Region of Devon Island Ice Cap, Canada |
title_full_unstemmed |
Application of a Flow Model to the Ice-divide Region of Devon Island Ice Cap, Canada |
title_sort |
application of a flow model to the ice-divide region of devon island ice cap, canada |
publisher |
Cambridge University Press (CUP) |
publishDate |
1988 |
url |
http://dx.doi.org/10.1017/s0022143000009060 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000009060 |
genre |
Devon Island Ice cap Journal of Glaciology |
genre_facet |
Devon Island Ice cap Journal of Glaciology |
op_source |
Journal of Glaciology volume 34, issue 116, page 55-63 ISSN 0022-1430 1727-5652 |
op_doi |
https://doi.org/10.1017/s0022143000009060 |
container_title |
Journal of Glaciology |
container_volume |
34 |
container_issue |
116 |
container_start_page |
55 |
op_container_end_page |
63 |
_version_ |
1810441129707962368 |