Radar characterization of ice crystal orientation fabric and anisotropic rheology within Rutford Ice Stream, 2017-2019
We use polarimetric radar sounding to investigate variation in ice crystal orientation fabric within the near-surface (top 40-300 m) of Rutford Ice Stream, West Antarctica. To assess the influence of the fabric on ice flow, we use an analytical model to derive anisotropic enhancements of the flow la...
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Language: | English |
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UK Polar Data Centre, Natural Environment Research Council, UK Research & Innovation
2020
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Online Access: | https://dx.doi.org/10.5285/d5b7e5a1-b04d-48d8-a440-c010658ec146 https://data.bas.ac.uk/full-record.php?id=GB/NERC/BAS/PDC/01428 |
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ftdatacite:10.5285/d5b7e5a1-b04d-48d8-a440-c010658ec146 |
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record_format |
openpolar |
institution |
Open Polar |
collection |
DataCite Metadata Store (German National Library of Science and Technology) |
op_collection_id |
ftdatacite |
language |
English |
topic |
"EARTH SCIENCE","CRYOSPHERE","GLACIERS/ICE SHEETS","GLACIER MOTION/ICE SHEET MOTION" "EARTH SCIENCE","CRYOSPHERE","GLACIERS/ICE SHEETS" "EARTH SCIENCE","SPECTRAL/ENGINEERING","RADAR" anisotropy fabric ice flow polarimetry radar rheology |
spellingShingle |
"EARTH SCIENCE","CRYOSPHERE","GLACIERS/ICE SHEETS","GLACIER MOTION/ICE SHEET MOTION" "EARTH SCIENCE","CRYOSPHERE","GLACIERS/ICE SHEETS" "EARTH SCIENCE","SPECTRAL/ENGINEERING","RADAR" anisotropy fabric ice flow polarimetry radar rheology Jordan, Tom Martin, Carlos Brisbourne, Alex Schroeder, Dustin Smith, Andrew Radar characterization of ice crystal orientation fabric and anisotropic rheology within Rutford Ice Stream, 2017-2019 |
topic_facet |
"EARTH SCIENCE","CRYOSPHERE","GLACIERS/ICE SHEETS","GLACIER MOTION/ICE SHEET MOTION" "EARTH SCIENCE","CRYOSPHERE","GLACIERS/ICE SHEETS" "EARTH SCIENCE","SPECTRAL/ENGINEERING","RADAR" anisotropy fabric ice flow polarimetry radar rheology |
description |
We use polarimetric radar sounding to investigate variation in ice crystal orientation fabric within the near-surface (top 40-300 m) of Rutford Ice Stream, West Antarctica. To assess the influence of the fabric on ice flow, we use an analytical model to derive anisotropic enhancements of the flow law from the fabric measurements. In the shallowest ice (40-100 m) the azimuthal fabric orientation is consistent with flow-induced development and correlates with the surface strain field. Notably, toward the ice-stream margins, both the horizontal compression angle and fabric orientation tend toward 45 degrees relative to ice flow. This result is consistent with theoretical predictions of flow-induced fabric under simple shear, but to our knowledge has never been observed. The fabric orientation in deeper ice (100-300 m) is significantly misaligned with shallower ice in some locations, and therefore inconsistent with the local surface strain field. This result represents a new challenge for ice flow models which typically infer basal properties from the surface conditions assuming simplified vertical variation of ice flow. Our technique retrieves azimuthal variations in fabric but is insensitive to vertical variation, and we therefore constrain the fabric and rheology within two end-members: a vertical girdle or a horizontal pole. Our hypotheses are that fabric near the center of the ice-stream tends to a vertical girdle that enhances horizontal compression, and near the ice-stream margins tends to a horizontal pole that enhances lateral shear. ApRES radar data were collected as part of the BEAMISH Project (NERC AFI award numbers NE/G014159/1 and NE/G013187/1). Tom Jordan would like to acknowledge support from EU Horizon 2020 grant 747336-BRISRES-H2020-MSCA-IF-2016. : Polarimetric data acquisition follows Brisbourne et al. 2019. This paper describes the quad-polarized measurement technique that was applied in the field. ApRES signal processing follows Brennan et al. 2014. This paper describes the processing steps applied to the raw data to generate ice-depth profiles for the phase and amplitude of radar wave. Polarimetric data processing follows Jordan et al. 2019. This paper describes the coherence methodology that is used to determine the quality of the radar data for fabric estimation. : Radar: ApRES (British Antarctic Survey's Autonomous phase-sensitive Radio-Echo Sounder) - chirps of 200 to 400 MHz in time intervals of 1 s. : Polarimetric data quality is established from the coherence magnitude, which provides a metric for sections of the ice column where fabric can be reliably estimated. Fabric estimates could be made in the top 100-200 m of the ice column at 18 of the 20 measurement sites (maximum depth ~ 100 m near the shear-margin, and ~200 m in the ice-stream centre). |
format |
Dataset |
author |
Jordan, Tom Martin, Carlos Brisbourne, Alex Schroeder, Dustin Smith, Andrew |
author_facet |
Jordan, Tom Martin, Carlos Brisbourne, Alex Schroeder, Dustin Smith, Andrew |
author_sort |
Jordan, Tom |
title |
Radar characterization of ice crystal orientation fabric and anisotropic rheology within Rutford Ice Stream, 2017-2019 |
title_short |
Radar characterization of ice crystal orientation fabric and anisotropic rheology within Rutford Ice Stream, 2017-2019 |
title_full |
Radar characterization of ice crystal orientation fabric and anisotropic rheology within Rutford Ice Stream, 2017-2019 |
title_fullStr |
Radar characterization of ice crystal orientation fabric and anisotropic rheology within Rutford Ice Stream, 2017-2019 |
title_full_unstemmed |
Radar characterization of ice crystal orientation fabric and anisotropic rheology within Rutford Ice Stream, 2017-2019 |
title_sort |
radar characterization of ice crystal orientation fabric and anisotropic rheology within rutford ice stream, 2017-2019 |
publisher |
UK Polar Data Centre, Natural Environment Research Council, UK Research & Innovation |
publishDate |
2020 |
url |
https://dx.doi.org/10.5285/d5b7e5a1-b04d-48d8-a440-c010658ec146 https://data.bas.ac.uk/full-record.php?id=GB/NERC/BAS/PDC/01428 |
long_lat |
ENVELOPE(-85.300,-85.300,-78.600,-78.600) ENVELOPE(-80.000,-80.000,-79.167,-79.167) |
geographic |
Antarctic Rutford Rutford Ice Stream West Antarctica |
geographic_facet |
Antarctic Rutford Rutford Ice Stream West Antarctica |
genre |
Antarc* Antarctic Antarctica Ice Sheet Rutford Ice Stream West Antarctica |
genre_facet |
Antarc* Antarctic Antarctica Ice Sheet Rutford Ice Stream West Antarctica |
op_relation |
https://www.bas.ac.uk/project/basal-conditions-on-rutford-ice-stream/ https://www.bas.ac.uk/polar-operations/sites-and-facilities/facility/phase-sensitive-radar-apres/ https://dx.doi.org/10.1029/2018jf004776 https://dx.doi.org/10.1109/tgrs.2019.2921980 https://dx.doi.org/10.1049/iet-rsn.2013.0053 https://www.bas.ac.uk/project/basal-conditions-on-rutford-ice-stream/ https://www.bas.ac.uk/polar-operations/sites-and-facilities/facility/phase-sensitive-radar-apres/ |
op_rights |
Open Government Licence V3.0 http://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/ |
op_doi |
https://doi.org/10.5285/d5b7e5a1-b04d-48d8-a440-c010658ec146 https://doi.org/10.1029/2018jf004776 https://doi.org/10.1109/tgrs.2019.2921980 https://doi.org/10.1049/iet-rsn.2013.0053 |
_version_ |
1766203278215872512 |
spelling |
ftdatacite:10.5285/d5b7e5a1-b04d-48d8-a440-c010658ec146 2023-05-15T13:44:33+02:00 Radar characterization of ice crystal orientation fabric and anisotropic rheology within Rutford Ice Stream, 2017-2019 Jordan, Tom Martin, Carlos Brisbourne, Alex Schroeder, Dustin Smith, Andrew 2020 application/x-hdf application/netcdf text/plain text/csv https://dx.doi.org/10.5285/d5b7e5a1-b04d-48d8-a440-c010658ec146 https://data.bas.ac.uk/full-record.php?id=GB/NERC/BAS/PDC/01428 en eng UK Polar Data Centre, Natural Environment Research Council, UK Research & Innovation https://www.bas.ac.uk/project/basal-conditions-on-rutford-ice-stream/ https://www.bas.ac.uk/polar-operations/sites-and-facilities/facility/phase-sensitive-radar-apres/ https://dx.doi.org/10.1029/2018jf004776 https://dx.doi.org/10.1109/tgrs.2019.2921980 https://dx.doi.org/10.1049/iet-rsn.2013.0053 https://www.bas.ac.uk/project/basal-conditions-on-rutford-ice-stream/ https://www.bas.ac.uk/polar-operations/sites-and-facilities/facility/phase-sensitive-radar-apres/ Open Government Licence V3.0 http://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/ "EARTH SCIENCE","CRYOSPHERE","GLACIERS/ICE SHEETS","GLACIER MOTION/ICE SHEET MOTION" "EARTH SCIENCE","CRYOSPHERE","GLACIERS/ICE SHEETS" "EARTH SCIENCE","SPECTRAL/ENGINEERING","RADAR" anisotropy fabric ice flow polarimetry radar rheology dataset Dataset anisotropy,fabric,ice flow,polarimetry,radar,rheology 2020 ftdatacite https://doi.org/10.5285/d5b7e5a1-b04d-48d8-a440-c010658ec146 https://doi.org/10.1029/2018jf004776 https://doi.org/10.1109/tgrs.2019.2921980 https://doi.org/10.1049/iet-rsn.2013.0053 2021-11-05T12:55:41Z We use polarimetric radar sounding to investigate variation in ice crystal orientation fabric within the near-surface (top 40-300 m) of Rutford Ice Stream, West Antarctica. To assess the influence of the fabric on ice flow, we use an analytical model to derive anisotropic enhancements of the flow law from the fabric measurements. In the shallowest ice (40-100 m) the azimuthal fabric orientation is consistent with flow-induced development and correlates with the surface strain field. Notably, toward the ice-stream margins, both the horizontal compression angle and fabric orientation tend toward 45 degrees relative to ice flow. This result is consistent with theoretical predictions of flow-induced fabric under simple shear, but to our knowledge has never been observed. The fabric orientation in deeper ice (100-300 m) is significantly misaligned with shallower ice in some locations, and therefore inconsistent with the local surface strain field. This result represents a new challenge for ice flow models which typically infer basal properties from the surface conditions assuming simplified vertical variation of ice flow. Our technique retrieves azimuthal variations in fabric but is insensitive to vertical variation, and we therefore constrain the fabric and rheology within two end-members: a vertical girdle or a horizontal pole. Our hypotheses are that fabric near the center of the ice-stream tends to a vertical girdle that enhances horizontal compression, and near the ice-stream margins tends to a horizontal pole that enhances lateral shear. ApRES radar data were collected as part of the BEAMISH Project (NERC AFI award numbers NE/G014159/1 and NE/G013187/1). Tom Jordan would like to acknowledge support from EU Horizon 2020 grant 747336-BRISRES-H2020-MSCA-IF-2016. : Polarimetric data acquisition follows Brisbourne et al. 2019. This paper describes the quad-polarized measurement technique that was applied in the field. ApRES signal processing follows Brennan et al. 2014. This paper describes the processing steps applied to the raw data to generate ice-depth profiles for the phase and amplitude of radar wave. Polarimetric data processing follows Jordan et al. 2019. This paper describes the coherence methodology that is used to determine the quality of the radar data for fabric estimation. : Radar: ApRES (British Antarctic Survey's Autonomous phase-sensitive Radio-Echo Sounder) - chirps of 200 to 400 MHz in time intervals of 1 s. : Polarimetric data quality is established from the coherence magnitude, which provides a metric for sections of the ice column where fabric can be reliably estimated. Fabric estimates could be made in the top 100-200 m of the ice column at 18 of the 20 measurement sites (maximum depth ~ 100 m near the shear-margin, and ~200 m in the ice-stream centre). Dataset Antarc* Antarctic Antarctica Ice Sheet Rutford Ice Stream West Antarctica DataCite Metadata Store (German National Library of Science and Technology) Antarctic Rutford ENVELOPE(-85.300,-85.300,-78.600,-78.600) Rutford Ice Stream ENVELOPE(-80.000,-80.000,-79.167,-79.167) West Antarctica |