Subglacial roughness of the Greenland Ice Sheet: relationship with contemporary ice velocity and geology
The subglacial environment of the Greenland Ice Sheet (GrIS) is poorly constrained both in its bulk properties, for example geology, the presence of sediment, and the presence of water, and interfacial conditions, such as roughness and bed rheology. There is, therefore, limited understanding of how...
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European Geosciences Union
2019
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Online Access: | http://nora.nerc.ac.uk/id/eprint/526548/ https://nora.nerc.ac.uk/id/eprint/526548/1/tc-13-3093-2019.pdf https://doi.org/10.5194/tc-13-3093-2019 |
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ftnerc:oai:nora.nerc.ac.uk:526548 2023-05-15T16:28:14+02:00 Subglacial roughness of the Greenland Ice Sheet: relationship with contemporary ice velocity and geology Cooper, Michael A. Jordan, Thomas M. Schroeder, Dustin M. Siegert, Martin J. Williams, Christopher N. Bamber, Jonathan L. 2019-11-26 text http://nora.nerc.ac.uk/id/eprint/526548/ https://nora.nerc.ac.uk/id/eprint/526548/1/tc-13-3093-2019.pdf https://doi.org/10.5194/tc-13-3093-2019 en eng European Geosciences Union https://nora.nerc.ac.uk/id/eprint/526548/1/tc-13-3093-2019.pdf Cooper, Michael A.; Jordan, Thomas M.; Schroeder, Dustin M.; Siegert, Martin J.; Williams, Christopher N.; Bamber, Jonathan L. 2019 Subglacial roughness of the Greenland Ice Sheet: relationship with contemporary ice velocity and geology. The Cryosphere, 13 (11). 3093-3115. https://doi.org/10.5194/tc-13-3093-2019 <https://doi.org/10.5194/tc-13-3093-2019> cc_by_4 CC-BY Publication - Article PeerReviewed 2019 ftnerc https://doi.org/10.5194/tc-13-3093-2019 2023-02-04T19:50:02Z The subglacial environment of the Greenland Ice Sheet (GrIS) is poorly constrained both in its bulk properties, for example geology, the presence of sediment, and the presence of water, and interfacial conditions, such as roughness and bed rheology. There is, therefore, limited understanding of how spatially heterogeneous subglacial properties relate to ice-sheet motion. Here, via analysis of 2 decades of radio-echo sounding data, we present a new systematic analysis of subglacial roughness beneath the GrIS. We use two independent methods to quantify subglacial roughness: first, the variability in along-track topography – enabling an assessment of roughness anisotropy from pairs of orthogonal transects aligned perpendicular and parallel to ice flow and, second, from bed-echo scattering – enabling assessment of fine-scale bed characteristics. We establish the spatial distribution of subglacial roughness and quantify its relationship with ice flow speed and direction. Overall, the beds of fast-flowing regions are observed to be rougher than the slow-flowing interior. Topographic roughness exhibits an exponential scaling relationship with ice surface velocity parallel, but not perpendicular, to flow direction in fast-flowing regions, and the degree of anisotropy is correlated with ice surface speed. In many slow-flowing regions both roughness methods indicate spatially coherent regions of smooth beds, which, through combination with analyses of underlying geology, we conclude is likely due to the presence of a hard flat bed. Consequently, the study provides scope for a spatially variable hard- or soft-bed boundary constraint for ice-sheet models. Article in Journal/Newspaper Greenland Ice Sheet The Cryosphere Natural Environment Research Council: NERC Open Research Archive Greenland The Cryosphere 13 11 3093 3115 |
institution |
Open Polar |
collection |
Natural Environment Research Council: NERC Open Research Archive |
op_collection_id |
ftnerc |
language |
English |
description |
The subglacial environment of the Greenland Ice Sheet (GrIS) is poorly constrained both in its bulk properties, for example geology, the presence of sediment, and the presence of water, and interfacial conditions, such as roughness and bed rheology. There is, therefore, limited understanding of how spatially heterogeneous subglacial properties relate to ice-sheet motion. Here, via analysis of 2 decades of radio-echo sounding data, we present a new systematic analysis of subglacial roughness beneath the GrIS. We use two independent methods to quantify subglacial roughness: first, the variability in along-track topography – enabling an assessment of roughness anisotropy from pairs of orthogonal transects aligned perpendicular and parallel to ice flow and, second, from bed-echo scattering – enabling assessment of fine-scale bed characteristics. We establish the spatial distribution of subglacial roughness and quantify its relationship with ice flow speed and direction. Overall, the beds of fast-flowing regions are observed to be rougher than the slow-flowing interior. Topographic roughness exhibits an exponential scaling relationship with ice surface velocity parallel, but not perpendicular, to flow direction in fast-flowing regions, and the degree of anisotropy is correlated with ice surface speed. In many slow-flowing regions both roughness methods indicate spatially coherent regions of smooth beds, which, through combination with analyses of underlying geology, we conclude is likely due to the presence of a hard flat bed. Consequently, the study provides scope for a spatially variable hard- or soft-bed boundary constraint for ice-sheet models. |
format |
Article in Journal/Newspaper |
author |
Cooper, Michael A. Jordan, Thomas M. Schroeder, Dustin M. Siegert, Martin J. Williams, Christopher N. Bamber, Jonathan L. |
spellingShingle |
Cooper, Michael A. Jordan, Thomas M. Schroeder, Dustin M. Siegert, Martin J. Williams, Christopher N. Bamber, Jonathan L. Subglacial roughness of the Greenland Ice Sheet: relationship with contemporary ice velocity and geology |
author_facet |
Cooper, Michael A. Jordan, Thomas M. Schroeder, Dustin M. Siegert, Martin J. Williams, Christopher N. Bamber, Jonathan L. |
author_sort |
Cooper, Michael A. |
title |
Subglacial roughness of the Greenland Ice Sheet: relationship with contemporary ice velocity and geology |
title_short |
Subglacial roughness of the Greenland Ice Sheet: relationship with contemporary ice velocity and geology |
title_full |
Subglacial roughness of the Greenland Ice Sheet: relationship with contemporary ice velocity and geology |
title_fullStr |
Subglacial roughness of the Greenland Ice Sheet: relationship with contemporary ice velocity and geology |
title_full_unstemmed |
Subglacial roughness of the Greenland Ice Sheet: relationship with contemporary ice velocity and geology |
title_sort |
subglacial roughness of the greenland ice sheet: relationship with contemporary ice velocity and geology |
publisher |
European Geosciences Union |
publishDate |
2019 |
url |
http://nora.nerc.ac.uk/id/eprint/526548/ https://nora.nerc.ac.uk/id/eprint/526548/1/tc-13-3093-2019.pdf https://doi.org/10.5194/tc-13-3093-2019 |
geographic |
Greenland |
geographic_facet |
Greenland |
genre |
Greenland Ice Sheet The Cryosphere |
genre_facet |
Greenland Ice Sheet The Cryosphere |
op_relation |
https://nora.nerc.ac.uk/id/eprint/526548/1/tc-13-3093-2019.pdf Cooper, Michael A.; Jordan, Thomas M.; Schroeder, Dustin M.; Siegert, Martin J.; Williams, Christopher N.; Bamber, Jonathan L. 2019 Subglacial roughness of the Greenland Ice Sheet: relationship with contemporary ice velocity and geology. The Cryosphere, 13 (11). 3093-3115. https://doi.org/10.5194/tc-13-3093-2019 <https://doi.org/10.5194/tc-13-3093-2019> |
op_rights |
cc_by_4 |
op_rightsnorm |
CC-BY |
op_doi |
https://doi.org/10.5194/tc-13-3093-2019 |
container_title |
The Cryosphere |
container_volume |
13 |
container_issue |
11 |
container_start_page |
3093 |
op_container_end_page |
3115 |
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1766017862505332736 |