Inversion of basal friction in Antarctica using exact and incomplete adjoints of a higher-order model
Basal friction beneath ice sheets remains poorly characterized and yet is a fundamental control on ice mechanics. Here we use a complete map of surface velocity of the Antarctic Ice Sheet to infer the basal friction over the entire continent by combining these observations with a three-dimensional,...
Published in: | Journal of Geophysical Research: Earth Surface |
---|---|
Main Authors: | , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
eScholarship, University of California
2013
|
Subjects: | |
Online Access: | http://www.escholarship.org/uc/item/4j39c4v4 |
id |
ftcdlib:qt4j39c4v4 |
---|---|
record_format |
openpolar |
spelling |
ftcdlib:qt4j39c4v4 2023-05-15T13:50:53+02:00 Inversion of basal friction in Antarctica using exact and incomplete adjoints of a higher-order model Morlighem, M Seroussi, H Larour, E Rignot, E 1746 - 1753 2013-09-01 application/pdf http://www.escholarship.org/uc/item/4j39c4v4 english eng eScholarship, University of California qt4j39c4v4 http://www.escholarship.org/uc/item/4j39c4v4 Attribution (CC BY): http://creativecommons.org/licenses/by/3.0/ CC-BY Morlighem, M; Seroussi, H; Larour, E; & Rignot, E. (2013). Inversion of basal friction in Antarctica using exact and incomplete adjoints of a higher-order model. Journal of Geophysical Research: Earth Surface, 118(3), 1746 - 1753. doi:10.1002/jgrf.20125. UC Irvine: Retrieved from: http://www.escholarship.org/uc/item/4j39c4v4 article 2013 ftcdlib https://doi.org/10.1002/jgrf.20125 2018-07-13T22:53:34Z Basal friction beneath ice sheets remains poorly characterized and yet is a fundamental control on ice mechanics. Here we use a complete map of surface velocity of the Antarctic Ice Sheet to infer the basal friction over the entire continent by combining these observations with a three-dimensional, thermomechanical, higher-order ice sheet numerical model from the Ice Sheet System Model open source software. We demonstrate that inverse methods can be readily applied at the continental scale with appropriate selections of cost function and of scheme of regularization, at a spatial resolution as high as 3 km along the coastline. We compare the convergence of two descent algorithms with the exact and incomplete adjoints to show that the incomplete adjoint is an excellent approximation. The results reveal that the driving stress is almost entirely balanced by the basal shear stress over 80% of the ice sheet. The basal friction coefficient, which relates basal friction to basal velocity, is, however, significantly heterogeneous: it is low on fast moving ice and high near topographic divides. Areas with low values extend far out into the interior, along glacier and ice stream tributaries, almost to the flanks of topographic divides, suggesting that basal sliding is widespread beneath the Antarctic Ice Sheet. ©2013. American Geophysical Union. All Rights Reserved. Article in Journal/Newspaper Antarc* Antarctic Antarctica Ice Sheet University of California: eScholarship Antarctic The Antarctic Journal of Geophysical Research: Earth Surface 118 3 1746 1753 |
institution |
Open Polar |
collection |
University of California: eScholarship |
op_collection_id |
ftcdlib |
language |
English |
description |
Basal friction beneath ice sheets remains poorly characterized and yet is a fundamental control on ice mechanics. Here we use a complete map of surface velocity of the Antarctic Ice Sheet to infer the basal friction over the entire continent by combining these observations with a three-dimensional, thermomechanical, higher-order ice sheet numerical model from the Ice Sheet System Model open source software. We demonstrate that inverse methods can be readily applied at the continental scale with appropriate selections of cost function and of scheme of regularization, at a spatial resolution as high as 3 km along the coastline. We compare the convergence of two descent algorithms with the exact and incomplete adjoints to show that the incomplete adjoint is an excellent approximation. The results reveal that the driving stress is almost entirely balanced by the basal shear stress over 80% of the ice sheet. The basal friction coefficient, which relates basal friction to basal velocity, is, however, significantly heterogeneous: it is low on fast moving ice and high near topographic divides. Areas with low values extend far out into the interior, along glacier and ice stream tributaries, almost to the flanks of topographic divides, suggesting that basal sliding is widespread beneath the Antarctic Ice Sheet. ©2013. American Geophysical Union. All Rights Reserved. |
format |
Article in Journal/Newspaper |
author |
Morlighem, M Seroussi, H Larour, E Rignot, E |
spellingShingle |
Morlighem, M Seroussi, H Larour, E Rignot, E Inversion of basal friction in Antarctica using exact and incomplete adjoints of a higher-order model |
author_facet |
Morlighem, M Seroussi, H Larour, E Rignot, E |
author_sort |
Morlighem, M |
title |
Inversion of basal friction in Antarctica using exact and incomplete adjoints of a higher-order model |
title_short |
Inversion of basal friction in Antarctica using exact and incomplete adjoints of a higher-order model |
title_full |
Inversion of basal friction in Antarctica using exact and incomplete adjoints of a higher-order model |
title_fullStr |
Inversion of basal friction in Antarctica using exact and incomplete adjoints of a higher-order model |
title_full_unstemmed |
Inversion of basal friction in Antarctica using exact and incomplete adjoints of a higher-order model |
title_sort |
inversion of basal friction in antarctica using exact and incomplete adjoints of a higher-order model |
publisher |
eScholarship, University of California |
publishDate |
2013 |
url |
http://www.escholarship.org/uc/item/4j39c4v4 |
op_coverage |
1746 - 1753 |
geographic |
Antarctic The Antarctic |
geographic_facet |
Antarctic The Antarctic |
genre |
Antarc* Antarctic Antarctica Ice Sheet |
genre_facet |
Antarc* Antarctic Antarctica Ice Sheet |
op_source |
Morlighem, M; Seroussi, H; Larour, E; & Rignot, E. (2013). Inversion of basal friction in Antarctica using exact and incomplete adjoints of a higher-order model. Journal of Geophysical Research: Earth Surface, 118(3), 1746 - 1753. doi:10.1002/jgrf.20125. UC Irvine: Retrieved from: http://www.escholarship.org/uc/item/4j39c4v4 |
op_relation |
qt4j39c4v4 http://www.escholarship.org/uc/item/4j39c4v4 |
op_rights |
Attribution (CC BY): http://creativecommons.org/licenses/by/3.0/ |
op_rightsnorm |
CC-BY |
op_doi |
https://doi.org/10.1002/jgrf.20125 |
container_title |
Journal of Geophysical Research: Earth Surface |
container_volume |
118 |
container_issue |
3 |
container_start_page |
1746 |
op_container_end_page |
1753 |
_version_ |
1766254259146326016 |