Polarimetric radar reveals the spatial distribution of ice fabric at domes and divides in East Antarctica
Ice crystals are mechanically and dielectrically anisotropic. They progressively align under cumulative deformation, forming an ice-crystal-orientation fabric that, in turn, impacts ice deformation. However, almost all the observations of ice fabric are from ice core analysis, and its influence on t...
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ftdoajarticles:oai:doaj.org/article:ed73e4453ef8493d84a64e8249fe194d 2023-05-15T13:30:24+02:00 Polarimetric radar reveals the spatial distribution of ice fabric at domes and divides in East Antarctica M. R. Ershadi R. Drews C. Martín O. Eisen C. Ritz H. Corr J. Christmann O. Zeising A. Humbert R. Mulvaney 2022-05-01T00:00:00Z https://doi.org/10.5194/tc-16-1719-2022 https://doaj.org/article/ed73e4453ef8493d84a64e8249fe194d EN eng Copernicus Publications https://tc.copernicus.org/articles/16/1719/2022/tc-16-1719-2022.pdf https://doaj.org/toc/1994-0416 https://doaj.org/toc/1994-0424 doi:10.5194/tc-16-1719-2022 1994-0416 1994-0424 https://doaj.org/article/ed73e4453ef8493d84a64e8249fe194d The Cryosphere, Vol 16, Pp 1719-1739 (2022) Environmental sciences GE1-350 Geology QE1-996.5 article 2022 ftdoajarticles https://doi.org/10.5194/tc-16-1719-2022 2022-12-31T00:09:37Z Ice crystals are mechanically and dielectrically anisotropic. They progressively align under cumulative deformation, forming an ice-crystal-orientation fabric that, in turn, impacts ice deformation. However, almost all the observations of ice fabric are from ice core analysis, and its influence on the ice flow is unclear. Here, we present a non-linear inverse approach to process co- and cross-polarized phase-sensitive radar data. We estimate the continuous depth profile of georeferenced ice fabric orientation along with the reflection ratio and horizontal anisotropy of the ice column. Our method approximates the complete second-order orientation tensor and all the ice fabric eigenvalues. As a result, we infer the vertical ice fabric anisotropy, which is an essential factor to better understand ice deformation using anisotropic ice flow models. The approach is validated at two Antarctic ice core sites (EPICA (European Project for Ice Coring in Antarctica) Dome C and EPICA Dronning Maud Land) in contrasting flow regimes. Spatial variability in ice fabric characteristics in the dome-to-flank transition near Dome C is quantified with 20 more sites located along with a 36 km long cross-section. Local horizontal anisotropy increases under the dome summit and decreases away from the dome summit. We suggest that this is a consequence of the non-linear rheology of ice, also known as the Raymond effect. On larger spatial scales, horizontal anisotropy increases with increasing distance from the dome. At most of the sites, the main driver of ice fabric evolution is vertical compression, yet our data show that the horizontal distribution of the ice fabric is consistent with the present horizontal flow. This method uses polarimetric-radar data, which are suitable for profiling radar applications and are able to constrain ice fabric distribution on a spatial scale comparable to ice flow observations and models. Article in Journal/Newspaper Antarc* Antarctic Antarctica Dronning Maud Land East Antarctica EPICA ice core The Cryosphere Directory of Open Access Journals: DOAJ Articles Antarctic East Antarctica Dronning Maud Land The Cryosphere 16 5 1719 1739 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Environmental sciences GE1-350 Geology QE1-996.5 |
spellingShingle |
Environmental sciences GE1-350 Geology QE1-996.5 M. R. Ershadi R. Drews C. Martín O. Eisen C. Ritz H. Corr J. Christmann O. Zeising A. Humbert R. Mulvaney Polarimetric radar reveals the spatial distribution of ice fabric at domes and divides in East Antarctica |
topic_facet |
Environmental sciences GE1-350 Geology QE1-996.5 |
description |
Ice crystals are mechanically and dielectrically anisotropic. They progressively align under cumulative deformation, forming an ice-crystal-orientation fabric that, in turn, impacts ice deformation. However, almost all the observations of ice fabric are from ice core analysis, and its influence on the ice flow is unclear. Here, we present a non-linear inverse approach to process co- and cross-polarized phase-sensitive radar data. We estimate the continuous depth profile of georeferenced ice fabric orientation along with the reflection ratio and horizontal anisotropy of the ice column. Our method approximates the complete second-order orientation tensor and all the ice fabric eigenvalues. As a result, we infer the vertical ice fabric anisotropy, which is an essential factor to better understand ice deformation using anisotropic ice flow models. The approach is validated at two Antarctic ice core sites (EPICA (European Project for Ice Coring in Antarctica) Dome C and EPICA Dronning Maud Land) in contrasting flow regimes. Spatial variability in ice fabric characteristics in the dome-to-flank transition near Dome C is quantified with 20 more sites located along with a 36 km long cross-section. Local horizontal anisotropy increases under the dome summit and decreases away from the dome summit. We suggest that this is a consequence of the non-linear rheology of ice, also known as the Raymond effect. On larger spatial scales, horizontal anisotropy increases with increasing distance from the dome. At most of the sites, the main driver of ice fabric evolution is vertical compression, yet our data show that the horizontal distribution of the ice fabric is consistent with the present horizontal flow. This method uses polarimetric-radar data, which are suitable for profiling radar applications and are able to constrain ice fabric distribution on a spatial scale comparable to ice flow observations and models. |
format |
Article in Journal/Newspaper |
author |
M. R. Ershadi R. Drews C. Martín O. Eisen C. Ritz H. Corr J. Christmann O. Zeising A. Humbert R. Mulvaney |
author_facet |
M. R. Ershadi R. Drews C. Martín O. Eisen C. Ritz H. Corr J. Christmann O. Zeising A. Humbert R. Mulvaney |
author_sort |
M. R. Ershadi |
title |
Polarimetric radar reveals the spatial distribution of ice fabric at domes and divides in East Antarctica |
title_short |
Polarimetric radar reveals the spatial distribution of ice fabric at domes and divides in East Antarctica |
title_full |
Polarimetric radar reveals the spatial distribution of ice fabric at domes and divides in East Antarctica |
title_fullStr |
Polarimetric radar reveals the spatial distribution of ice fabric at domes and divides in East Antarctica |
title_full_unstemmed |
Polarimetric radar reveals the spatial distribution of ice fabric at domes and divides in East Antarctica |
title_sort |
polarimetric radar reveals the spatial distribution of ice fabric at domes and divides in east antarctica |
publisher |
Copernicus Publications |
publishDate |
2022 |
url |
https://doi.org/10.5194/tc-16-1719-2022 https://doaj.org/article/ed73e4453ef8493d84a64e8249fe194d |
geographic |
Antarctic East Antarctica Dronning Maud Land |
geographic_facet |
Antarctic East Antarctica Dronning Maud Land |
genre |
Antarc* Antarctic Antarctica Dronning Maud Land East Antarctica EPICA ice core The Cryosphere |
genre_facet |
Antarc* Antarctic Antarctica Dronning Maud Land East Antarctica EPICA ice core The Cryosphere |
op_source |
The Cryosphere, Vol 16, Pp 1719-1739 (2022) |
op_relation |
https://tc.copernicus.org/articles/16/1719/2022/tc-16-1719-2022.pdf https://doaj.org/toc/1994-0416 https://doaj.org/toc/1994-0424 doi:10.5194/tc-16-1719-2022 1994-0416 1994-0424 https://doaj.org/article/ed73e4453ef8493d84a64e8249fe194d |
op_doi |
https://doi.org/10.5194/tc-16-1719-2022 |
container_title |
The Cryosphere |
container_volume |
16 |
container_issue |
5 |
container_start_page |
1719 |
op_container_end_page |
1739 |
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1766007936551747584 |