Sliding of temperate basal ice on a rough, hard bed: creep mechanisms, pressure melting, and implications for ice streaming
Basal ice motion is crucial to ice dynamics of ice sheets. The classic Weertman model for basal sliding over bedrock obstacles proposes that sliding velocity is controlled by pressure melting and/or ductile flow, whichever is the fastest; it further assumes that pressure melting is limited by heat f...
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ftcopernicus:oai:publications.copernicus.org:tc50010 2023-05-15T16:29:29+02:00 Sliding of temperate basal ice on a rough, hard bed: creep mechanisms, pressure melting, and implications for ice streaming Krabbendam, Maarten 2018-09-27 application/pdf https://doi.org/10.5194/tc-10-1915-2016 https://tc.copernicus.org/articles/10/1915/2016/ eng eng doi:10.5194/tc-10-1915-2016 https://tc.copernicus.org/articles/10/1915/2016/ eISSN: 1994-0424 Text 2018 ftcopernicus https://doi.org/10.5194/tc-10-1915-2016 2020-07-20T16:24:01Z Basal ice motion is crucial to ice dynamics of ice sheets. The classic Weertman model for basal sliding over bedrock obstacles proposes that sliding velocity is controlled by pressure melting and/or ductile flow, whichever is the fastest; it further assumes that pressure melting is limited by heat flow through the obstacle and ductile flow is controlled by standard power-law creep. These last two assumptions, however, are not applicable if a substantial basal layer of temperate ( T ∼ T melt ) ice is present. In that case, frictional melting can produce excess basal meltwater and efficient water flow, leading to near-thermal equilibrium. High-temperature ice creep experiments have shown a sharp weakening of a factor 5–10 close to T melt , suggesting standard power-law creep does not operate due to a switch to melt-assisted creep with a possible component of grain boundary melting. Pressure melting is controlled by meltwater production, heat advection by flowing meltwater to the next obstacle and heat conduction through ice/rock over half the obstacle height. No heat flow through the obstacle is required. Ice streaming over a rough, hard bed, as possibly in the Northeast Greenland Ice Stream, may be explained by enhanced basal motion in a thick temperate ice layer. Text Greenland Copernicus Publications: E-Journals Greenland Weertman ENVELOPE(-67.753,-67.753,-66.972,-66.972) The Cryosphere 10 5 1915 1932 |
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Open Polar |
collection |
Copernicus Publications: E-Journals |
op_collection_id |
ftcopernicus |
language |
English |
description |
Basal ice motion is crucial to ice dynamics of ice sheets. The classic Weertman model for basal sliding over bedrock obstacles proposes that sliding velocity is controlled by pressure melting and/or ductile flow, whichever is the fastest; it further assumes that pressure melting is limited by heat flow through the obstacle and ductile flow is controlled by standard power-law creep. These last two assumptions, however, are not applicable if a substantial basal layer of temperate ( T ∼ T melt ) ice is present. In that case, frictional melting can produce excess basal meltwater and efficient water flow, leading to near-thermal equilibrium. High-temperature ice creep experiments have shown a sharp weakening of a factor 5–10 close to T melt , suggesting standard power-law creep does not operate due to a switch to melt-assisted creep with a possible component of grain boundary melting. Pressure melting is controlled by meltwater production, heat advection by flowing meltwater to the next obstacle and heat conduction through ice/rock over half the obstacle height. No heat flow through the obstacle is required. Ice streaming over a rough, hard bed, as possibly in the Northeast Greenland Ice Stream, may be explained by enhanced basal motion in a thick temperate ice layer. |
format |
Text |
author |
Krabbendam, Maarten |
spellingShingle |
Krabbendam, Maarten Sliding of temperate basal ice on a rough, hard bed: creep mechanisms, pressure melting, and implications for ice streaming |
author_facet |
Krabbendam, Maarten |
author_sort |
Krabbendam, Maarten |
title |
Sliding of temperate basal ice on a rough, hard bed: creep mechanisms, pressure melting, and implications for ice streaming |
title_short |
Sliding of temperate basal ice on a rough, hard bed: creep mechanisms, pressure melting, and implications for ice streaming |
title_full |
Sliding of temperate basal ice on a rough, hard bed: creep mechanisms, pressure melting, and implications for ice streaming |
title_fullStr |
Sliding of temperate basal ice on a rough, hard bed: creep mechanisms, pressure melting, and implications for ice streaming |
title_full_unstemmed |
Sliding of temperate basal ice on a rough, hard bed: creep mechanisms, pressure melting, and implications for ice streaming |
title_sort |
sliding of temperate basal ice on a rough, hard bed: creep mechanisms, pressure melting, and implications for ice streaming |
publishDate |
2018 |
url |
https://doi.org/10.5194/tc-10-1915-2016 https://tc.copernicus.org/articles/10/1915/2016/ |
long_lat |
ENVELOPE(-67.753,-67.753,-66.972,-66.972) |
geographic |
Greenland Weertman |
geographic_facet |
Greenland Weertman |
genre |
Greenland |
genre_facet |
Greenland |
op_source |
eISSN: 1994-0424 |
op_relation |
doi:10.5194/tc-10-1915-2016 https://tc.copernicus.org/articles/10/1915/2016/ |
op_doi |
https://doi.org/10.5194/tc-10-1915-2016 |
container_title |
The Cryosphere |
container_volume |
10 |
container_issue |
5 |
container_start_page |
1915 |
op_container_end_page |
1932 |
_version_ |
1766019190307684352 |