Rapid and accurate polarimetric radar measurements of ice crystal fabric orientation at the Western Antarctic Ice Sheet (WAIS) Divide ice core site
The crystal orientation fabric (COF) of ice sheets records the past history of ice sheet deformation and influences present-day ice flow dynamics. Though not widely implemented, coherent ice-penetrating radar is able to detect bulk anisotropic fabric patterns by exploiting the birefringence of ice c...
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European Geosciences Union
2021
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ftnerc:oai:nora.nerc.ac.uk:528512 2023-05-15T13:41:45+02:00 Rapid and accurate polarimetric radar measurements of ice crystal fabric orientation at the Western Antarctic Ice Sheet (WAIS) Divide ice core site Young, Tun Jan Martin, Carlos Christoffersen, Poul Schroeder, Dustin M. Tulaczyk, Slawek M. Dawson, Eliza J. 2021-08-27 text http://nora.nerc.ac.uk/id/eprint/528512/ https://nora.nerc.ac.uk/id/eprint/528512/1/tc-2020-264.pdf https://tc.copernicus.org/articles/15/4117/2021/tc-15-4117-2021.html en eng European Geosciences Union https://nora.nerc.ac.uk/id/eprint/528512/1/tc-2020-264.pdf Young, Tun Jan; Martin, Carlos orcid:0000-0002-2661-169X Christoffersen, Poul; Schroeder, Dustin M.; Tulaczyk, Slawek M.; Dawson, Eliza J. 2021 Rapid and accurate polarimetric radar measurements of ice crystal fabric orientation at the Western Antarctic Ice Sheet (WAIS) Divide ice core site. The Cryosphere, 15 (8). 4117-4133. https://doi.org/10.5194/tc-15-4117-2021 <https://doi.org/10.5194/tc-15-4117-2021> cc_by_4 CC-BY Publication - Article PeerReviewed 2021 ftnerc https://doi.org/10.5194/tc-15-4117-2021 2023-02-04T19:51:07Z The crystal orientation fabric (COF) of ice sheets records the past history of ice sheet deformation and influences present-day ice flow dynamics. Though not widely implemented, coherent ice-penetrating radar is able to detect bulk anisotropic fabric patterns by exploiting the birefringence of ice crystals at radar frequencies, with the assumption that one of the crystallographic axes is aligned in the vertical direction. In this study, we conduct a suite of quad-polarimetric measurements consisting of four orthogonal antenna orientation combinations near the Western Antarctic Ice Sheet (WAIS) Divide ice core site. From these measurements, we are able to quantify the azimuthal fabric asymmetry at this site to a depth of 1400 m at a bulk-averaged resolution of up to 15 m. Our estimates of fabric asymmetry closely match corresponding fabric estimates directly measured from the WAIS Divide ice core. While ice core studies are often unable to determine the absolute fabric orientation due to core rotation during extraction, we are able to identify and conclude that the fabric orientation is depth-invariant to at least 1400 m, equivalent to 6700 years BP (years before 1950) and aligns closely with the modern surface strain direction at WAIS Divide. Our results support the claim that the deformation regime at WAIS Divide has not changed substantially through the majority of the Holocene. Rapid polarimetric determination of bulk fabric asymmetry and orientation compares well with much more laborious sample-based COF measurements from thin ice sections. Because it is the bulk-averaged fabric that ultimately influences ice flow, polarimetric radar methods provide an opportunity for its accurate and widespread mapping and its incorporation into ice flow models. Article in Journal/Newspaper Antarc* Antarctic ice core Ice Sheet The Cryosphere Natural Environment Research Council: NERC Open Research Archive Antarctic The Cryosphere 15 8 4117 4133 |
institution |
Open Polar |
collection |
Natural Environment Research Council: NERC Open Research Archive |
op_collection_id |
ftnerc |
language |
English |
description |
The crystal orientation fabric (COF) of ice sheets records the past history of ice sheet deformation and influences present-day ice flow dynamics. Though not widely implemented, coherent ice-penetrating radar is able to detect bulk anisotropic fabric patterns by exploiting the birefringence of ice crystals at radar frequencies, with the assumption that one of the crystallographic axes is aligned in the vertical direction. In this study, we conduct a suite of quad-polarimetric measurements consisting of four orthogonal antenna orientation combinations near the Western Antarctic Ice Sheet (WAIS) Divide ice core site. From these measurements, we are able to quantify the azimuthal fabric asymmetry at this site to a depth of 1400 m at a bulk-averaged resolution of up to 15 m. Our estimates of fabric asymmetry closely match corresponding fabric estimates directly measured from the WAIS Divide ice core. While ice core studies are often unable to determine the absolute fabric orientation due to core rotation during extraction, we are able to identify and conclude that the fabric orientation is depth-invariant to at least 1400 m, equivalent to 6700 years BP (years before 1950) and aligns closely with the modern surface strain direction at WAIS Divide. Our results support the claim that the deformation regime at WAIS Divide has not changed substantially through the majority of the Holocene. Rapid polarimetric determination of bulk fabric asymmetry and orientation compares well with much more laborious sample-based COF measurements from thin ice sections. Because it is the bulk-averaged fabric that ultimately influences ice flow, polarimetric radar methods provide an opportunity for its accurate and widespread mapping and its incorporation into ice flow models. |
format |
Article in Journal/Newspaper |
author |
Young, Tun Jan Martin, Carlos Christoffersen, Poul Schroeder, Dustin M. Tulaczyk, Slawek M. Dawson, Eliza J. |
spellingShingle |
Young, Tun Jan Martin, Carlos Christoffersen, Poul Schroeder, Dustin M. Tulaczyk, Slawek M. Dawson, Eliza J. Rapid and accurate polarimetric radar measurements of ice crystal fabric orientation at the Western Antarctic Ice Sheet (WAIS) Divide ice core site |
author_facet |
Young, Tun Jan Martin, Carlos Christoffersen, Poul Schroeder, Dustin M. Tulaczyk, Slawek M. Dawson, Eliza J. |
author_sort |
Young, Tun Jan |
title |
Rapid and accurate polarimetric radar measurements of ice crystal fabric orientation at the Western Antarctic Ice Sheet (WAIS) Divide ice core site |
title_short |
Rapid and accurate polarimetric radar measurements of ice crystal fabric orientation at the Western Antarctic Ice Sheet (WAIS) Divide ice core site |
title_full |
Rapid and accurate polarimetric radar measurements of ice crystal fabric orientation at the Western Antarctic Ice Sheet (WAIS) Divide ice core site |
title_fullStr |
Rapid and accurate polarimetric radar measurements of ice crystal fabric orientation at the Western Antarctic Ice Sheet (WAIS) Divide ice core site |
title_full_unstemmed |
Rapid and accurate polarimetric radar measurements of ice crystal fabric orientation at the Western Antarctic Ice Sheet (WAIS) Divide ice core site |
title_sort |
rapid and accurate polarimetric radar measurements of ice crystal fabric orientation at the western antarctic ice sheet (wais) divide ice core site |
publisher |
European Geosciences Union |
publishDate |
2021 |
url |
http://nora.nerc.ac.uk/id/eprint/528512/ https://nora.nerc.ac.uk/id/eprint/528512/1/tc-2020-264.pdf https://tc.copernicus.org/articles/15/4117/2021/tc-15-4117-2021.html |
geographic |
Antarctic |
geographic_facet |
Antarctic |
genre |
Antarc* Antarctic ice core Ice Sheet The Cryosphere |
genre_facet |
Antarc* Antarctic ice core Ice Sheet The Cryosphere |
op_relation |
https://nora.nerc.ac.uk/id/eprint/528512/1/tc-2020-264.pdf Young, Tun Jan; Martin, Carlos orcid:0000-0002-2661-169X Christoffersen, Poul; Schroeder, Dustin M.; Tulaczyk, Slawek M.; Dawson, Eliza J. 2021 Rapid and accurate polarimetric radar measurements of ice crystal fabric orientation at the Western Antarctic Ice Sheet (WAIS) Divide ice core site. The Cryosphere, 15 (8). 4117-4133. https://doi.org/10.5194/tc-15-4117-2021 <https://doi.org/10.5194/tc-15-4117-2021> |
op_rights |
cc_by_4 |
op_rightsnorm |
CC-BY |
op_doi |
https://doi.org/10.5194/tc-15-4117-2021 |
container_title |
The Cryosphere |
container_volume |
15 |
container_issue |
8 |
container_start_page |
4117 |
op_container_end_page |
4133 |
_version_ |
1766157050669170688 |