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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ftunivcam:oai:www.repository.cam.ac.uk:1810/325324 2024-01-14T10:02:26+01:00 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 2021-08-07 application/pdf https://www.repository.cam.ac.uk/handle/1810/325324 https://doi.org/10.17863/CAM.72780 eng eng Copernicus Publications http://dx.doi.org/10.5194/tc-15-4117-2021 The Cryosphere https://doi.org/10.5285/BA1CAF7A-D4E0-4671-972A-E567A25CCD2C https://www.repository.cam.ac.uk/handle/1810/325324 doi:10.17863/CAM.72780 Attribution 4.0 International (CC BY) http://creativecommons.org/licenses/by/4.0/ 37 Earth Sciences 3709 Physical Geography and Environmental Geoscience 3705 Geology Article 2021 ftunivcam https://doi.org/10.17863/CAM.7278010.5285/BA1CAF7A-D4E0-4671-972A-E567A25CCD2C 2023-12-21T23:23:29Z 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. Natural Environment Research Council (NERC) research grant NE/S006788/1 National Science Foundation (NSF) research grant #1739027 Article in Journal/Newspaper Antarc* Antarctic ice core Ice Sheet Apollo - University of Cambridge Repository Antarctic |
institution |
Open Polar |
collection |
Apollo - University of Cambridge Repository |
op_collection_id |
ftunivcam |
language |
English |
topic |
37 Earth Sciences 3709 Physical Geography and Environmental Geoscience 3705 Geology |
spellingShingle |
37 Earth Sciences 3709 Physical Geography and Environmental Geoscience 3705 Geology 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 |
topic_facet |
37 Earth Sciences 3709 Physical Geography and Environmental Geoscience 3705 Geology |
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. Natural Environment Research Council (NERC) research grant NE/S006788/1 National Science Foundation (NSF) research grant #1739027 |
format |
Article in Journal/Newspaper |
author |
Young, Tun Jan Martin, Carlos Christoffersen, Poul Schroeder, Dustin M Tulaczyk, Slawek M Dawson, Eliza J |
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 |
Copernicus Publications |
publishDate |
2021 |
url |
https://www.repository.cam.ac.uk/handle/1810/325324 https://doi.org/10.17863/CAM.72780 |
geographic |
Antarctic |
geographic_facet |
Antarctic |
genre |
Antarc* Antarctic ice core Ice Sheet |
genre_facet |
Antarc* Antarctic ice core Ice Sheet |
op_relation |
https://doi.org/10.5285/BA1CAF7A-D4E0-4671-972A-E567A25CCD2C https://www.repository.cam.ac.uk/handle/1810/325324 doi:10.17863/CAM.72780 |
op_rights |
Attribution 4.0 International (CC BY) http://creativecommons.org/licenses/by/4.0/ |
op_doi |
https://doi.org/10.17863/CAM.7278010.5285/BA1CAF7A-D4E0-4671-972A-E567A25CCD2C |
_version_ |
1788057445601378304 |