Quasi-static granular flow of ice mélange
We use Landsat 8 imagery to generate ice mélange velocity fields at Greenland’s three most productive outlet glaciers: Jakobshavn Isbræ, Helheim Glacier, and Kangerdlugssuaq Glacier. Winter velocity fields are generally steady and highly uniform. Summer velocity fields, on the other hand, tend to be...
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American Geophysical Union
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ftunivalaska:oai:scholarworks.alaska.edu:11122/9724 2023-05-15T16:56:51+02:00 Quasi-static granular flow of ice mélange Amundson, Jason M. Burton, J. C. 2019-01-08T18:29:29Z http://hdl.handle.net/11122/9724 en_US eng American Geophysical Union Amundson, J. M., & Burton, J. C. (2018). Quasi-static granular flow of ice mélange. Journal of Geophysical Research: Earth Surface, 123. https://doi.org/10.1029/2018JF004685 http://hdl.handle.net/11122/9724 Journal of Geophysical Research: Earth Surface Ice Melange Velocity Fields Jakobshavn Isbræ Helheim Glacier Kangerdlugssuaq Glacier Article 2019 ftunivalaska 2023-02-23T21:37:20Z We use Landsat 8 imagery to generate ice mélange velocity fields at Greenland’s three most productive outlet glaciers: Jakobshavn Isbræ, Helheim Glacier, and Kangerdlugssuaq Glacier. Winter velocity fields are generally steady and highly uniform. Summer velocity fields, on the other hand, tend to be much more variable and can be uniform, compressional, or extensional. We rarely observe compressional flow at Jakobshavn Isbræ or extensional flow at Helheim Glacier, while both are observed at Kangerdlugssuaq Glacier. Transverse velocity profiles from all three locations are suggestive of viscoplastic flow, in which deformation occurs primarily in shear zones along the fjord walls. We analyze the transverse profiles in the context of quasi-static flow using continuum rheologies for granular materials and find that the force per unit width that ice mélange exerts on glacier termini increases exponentially with the ice mélange length-to-width ratio and the effective coefficient of friction. Our estimates of ice mélange resistance are consistent with other independent estimates and suggest that ice mélange may be capable of inhibiting iceberg calving events, especially during winter. Moreover, our results provide geophysical-scale support for constitutive relationships for granular materials and suggest a potential avenue for modeling ice mélange dynamics with continuum models. From acknowledgments: Funding for this project was provided by the U.S. National Science Foundation (DMR-1506446 and DMR-1506307). Digital elevation models were provided by the Polar Geospatial Center under the U.S. National Science Foundation (OPP-1043681, OPP-1559691, and OPP-1542736) Yes Article in Journal/Newspaper Jakobshavn Jakobshavn isbræ University of Alaska: ScholarWorks@UA Jakobshavn Isbræ ENVELOPE(-49.917,-49.917,69.167,69.167) |
institution |
Open Polar |
collection |
University of Alaska: ScholarWorks@UA |
op_collection_id |
ftunivalaska |
language |
English |
topic |
Ice Melange Velocity Fields Jakobshavn Isbræ Helheim Glacier Kangerdlugssuaq Glacier |
spellingShingle |
Ice Melange Velocity Fields Jakobshavn Isbræ Helheim Glacier Kangerdlugssuaq Glacier Amundson, Jason M. Burton, J. C. Quasi-static granular flow of ice mélange |
topic_facet |
Ice Melange Velocity Fields Jakobshavn Isbræ Helheim Glacier Kangerdlugssuaq Glacier |
description |
We use Landsat 8 imagery to generate ice mélange velocity fields at Greenland’s three most productive outlet glaciers: Jakobshavn Isbræ, Helheim Glacier, and Kangerdlugssuaq Glacier. Winter velocity fields are generally steady and highly uniform. Summer velocity fields, on the other hand, tend to be much more variable and can be uniform, compressional, or extensional. We rarely observe compressional flow at Jakobshavn Isbræ or extensional flow at Helheim Glacier, while both are observed at Kangerdlugssuaq Glacier. Transverse velocity profiles from all three locations are suggestive of viscoplastic flow, in which deformation occurs primarily in shear zones along the fjord walls. We analyze the transverse profiles in the context of quasi-static flow using continuum rheologies for granular materials and find that the force per unit width that ice mélange exerts on glacier termini increases exponentially with the ice mélange length-to-width ratio and the effective coefficient of friction. Our estimates of ice mélange resistance are consistent with other independent estimates and suggest that ice mélange may be capable of inhibiting iceberg calving events, especially during winter. Moreover, our results provide geophysical-scale support for constitutive relationships for granular materials and suggest a potential avenue for modeling ice mélange dynamics with continuum models. From acknowledgments: Funding for this project was provided by the U.S. National Science Foundation (DMR-1506446 and DMR-1506307). Digital elevation models were provided by the Polar Geospatial Center under the U.S. National Science Foundation (OPP-1043681, OPP-1559691, and OPP-1542736) Yes |
format |
Article in Journal/Newspaper |
author |
Amundson, Jason M. Burton, J. C. |
author_facet |
Amundson, Jason M. Burton, J. C. |
author_sort |
Amundson, Jason M. |
title |
Quasi-static granular flow of ice mélange |
title_short |
Quasi-static granular flow of ice mélange |
title_full |
Quasi-static granular flow of ice mélange |
title_fullStr |
Quasi-static granular flow of ice mélange |
title_full_unstemmed |
Quasi-static granular flow of ice mélange |
title_sort |
quasi-static granular flow of ice mélange |
publisher |
American Geophysical Union |
publishDate |
2019 |
url |
http://hdl.handle.net/11122/9724 |
long_lat |
ENVELOPE(-49.917,-49.917,69.167,69.167) |
geographic |
Jakobshavn Isbræ |
geographic_facet |
Jakobshavn Isbræ |
genre |
Jakobshavn Jakobshavn isbræ |
genre_facet |
Jakobshavn Jakobshavn isbræ |
op_source |
Journal of Geophysical Research: Earth Surface |
op_relation |
Amundson, J. M., & Burton, J. C. (2018). Quasi-static granular flow of ice mélange. Journal of Geophysical Research: Earth Surface, 123. https://doi.org/10.1029/2018JF004685 http://hdl.handle.net/11122/9724 |
_version_ |
1766048034405220352 |