Large-scale ice flow over a viscous basal sediment: Theory and application to ice stream
Recent seismic studies of ice stream B, Antarctica and field analysis of mid-latitude glacial deposits suggest that deformable basal sediments (e.g., water-saturated till) are important in determining ice sheet flow. If the ratio of till viscosity to effective ice viscosity is small, vertical shear...
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ftciteseerx:oai:CiteSeerX.psu:10.1.1.471.5219 2023-05-15T13:57:36+02:00 Large-scale ice flow over a viscous basal sediment: Theory and application to ice stream Douglas R. Macayeal The Pennsylvania State University CiteSeerX Archives 1989 application/pdf http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.471.5219 http://websrv.cs.umt.edu/isis/images/5/50/MacAyeal89.pdf en eng http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.471.5219 http://websrv.cs.umt.edu/isis/images/5/50/MacAyeal89.pdf Metadata may be used without restrictions as long as the oai identifier remains attached to it. http://websrv.cs.umt.edu/isis/images/5/50/MacAyeal89.pdf text 1989 ftciteseerx 2016-01-08T07:18:55Z Recent seismic studies of ice stream B, Antarctica and field analysis of mid-latitude glacial deposits suggest that deformable basal sediments (e.g., water-saturated till) are important in determining ice sheet flow. If the ratio of till viscosity to effective ice viscosity is small, vertical shear associated with horizontal flow is confined to the deforming bed alone. Ice flow over a deformable bed is thus akin to that of floating ice shelves, because ice shelves flow over inviscid seawater. For some Antarctic ice streams, and possibly for portions of the late Wisconsin ice sheets in North America and Eurasia, basal drag associated with deforming basal sediment does not induce significant vertical gradients of horizontal velocity. Instead, basal drag affects the flow as if it were a horizontal body force balanced by longitudinal and transverse deviatoric stress gradients. Comparison of the observed flow of ice stream B to finite element simulations incorporating a viscous basal till suggest that a simple till theology is sufficient o explain the current velocity profile. These simulations also highlight the importance of horizontal deviatoric stress in regions where driving stress and basal stress do not locally balance. While bed deformation is critical to ice stream existence, sensitivity tests suggest that ice shelf back pressure is still a crucial control affecting ice stream response to atmospheric and oceanic climate. Text Antarc* Antarctic Antarctica Ice Sheet Ice Shelf Ice Shelves Ice Stream B Unknown Antarctic |
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ftciteseerx |
language |
English |
description |
Recent seismic studies of ice stream B, Antarctica and field analysis of mid-latitude glacial deposits suggest that deformable basal sediments (e.g., water-saturated till) are important in determining ice sheet flow. If the ratio of till viscosity to effective ice viscosity is small, vertical shear associated with horizontal flow is confined to the deforming bed alone. Ice flow over a deformable bed is thus akin to that of floating ice shelves, because ice shelves flow over inviscid seawater. For some Antarctic ice streams, and possibly for portions of the late Wisconsin ice sheets in North America and Eurasia, basal drag associated with deforming basal sediment does not induce significant vertical gradients of horizontal velocity. Instead, basal drag affects the flow as if it were a horizontal body force balanced by longitudinal and transverse deviatoric stress gradients. Comparison of the observed flow of ice stream B to finite element simulations incorporating a viscous basal till suggest that a simple till theology is sufficient o explain the current velocity profile. These simulations also highlight the importance of horizontal deviatoric stress in regions where driving stress and basal stress do not locally balance. While bed deformation is critical to ice stream existence, sensitivity tests suggest that ice shelf back pressure is still a crucial control affecting ice stream response to atmospheric and oceanic climate. |
author2 |
The Pennsylvania State University CiteSeerX Archives |
format |
Text |
author |
Douglas R. Macayeal |
spellingShingle |
Douglas R. Macayeal Large-scale ice flow over a viscous basal sediment: Theory and application to ice stream |
author_facet |
Douglas R. Macayeal |
author_sort |
Douglas R. Macayeal |
title |
Large-scale ice flow over a viscous basal sediment: Theory and application to ice stream |
title_short |
Large-scale ice flow over a viscous basal sediment: Theory and application to ice stream |
title_full |
Large-scale ice flow over a viscous basal sediment: Theory and application to ice stream |
title_fullStr |
Large-scale ice flow over a viscous basal sediment: Theory and application to ice stream |
title_full_unstemmed |
Large-scale ice flow over a viscous basal sediment: Theory and application to ice stream |
title_sort |
large-scale ice flow over a viscous basal sediment: theory and application to ice stream |
publishDate |
1989 |
url |
http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.471.5219 http://websrv.cs.umt.edu/isis/images/5/50/MacAyeal89.pdf |
geographic |
Antarctic |
geographic_facet |
Antarctic |
genre |
Antarc* Antarctic Antarctica Ice Sheet Ice Shelf Ice Shelves Ice Stream B |
genre_facet |
Antarc* Antarctic Antarctica Ice Sheet Ice Shelf Ice Shelves Ice Stream B |
op_source |
http://websrv.cs.umt.edu/isis/images/5/50/MacAyeal89.pdf |
op_relation |
http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.471.5219 http://websrv.cs.umt.edu/isis/images/5/50/MacAyeal89.pdf |
op_rights |
Metadata may be used without restrictions as long as the oai identifier remains attached to it. |
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1766265314940551168 |