Direct evidence for radar reflector originating from changes in crystal-orientation fabric
International audience The origin of a strong continuous radar reflector observed with airborne radio-echo sounding (RES) at the EPICA deep-drilling site in Dronning Maud Land, Antarctica, is identified as a transition in crystal fabric orientation from a vertical girdle- to increased single-pole or...
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ftccsdartic:oai:HAL:hal-00298518v1 2024-02-11T09:58:54+01:00 Direct evidence for radar reflector originating from changes in crystal-orientation fabric Eisen, O. Hamann, I. Kipfstuhl, S. Steinhage, D. Wilhelms, F. Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung = Alfred Wegener Institute for Polar and Marine Research = Institut Alfred-Wegener pour la recherche polaire et marine (AWI) Helmholtz-Gemeinschaft = Helmholtz Association 2007-06-15 https://hal.science/hal-00298518 https://hal.science/hal-00298518/document https://hal.science/hal-00298518/file/tcd-1-1-2007.pdf en eng HAL CCSD Copernicus hal-00298518 https://hal.science/hal-00298518 https://hal.science/hal-00298518/document https://hal.science/hal-00298518/file/tcd-1-1-2007.pdf info:eu-repo/semantics/OpenAccess ISSN: 1994-0432 EISSN: 1994-0440 The Cryosphere Discussions https://hal.science/hal-00298518 The Cryosphere Discussions, 2007, 1 (1), pp.1-16 [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces environment [SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere [SDU.STU]Sciences of the Universe [physics]/Earth Sciences info:eu-repo/semantics/article Journal articles 2007 ftccsdartic 2024-01-21T00:59:53Z International audience The origin of a strong continuous radar reflector observed with airborne radio-echo sounding (RES) at the EPICA deep-drilling site in Dronning Maud Land, Antarctica, is identified as a transition in crystal fabric orientation from a vertical girdle- to increased single-pole orientation seen along the ice core. The reflector is observed with a 60 ns and 600 ns long pulse at a frequency of 150 MHz, spans one pulse length, is continuous over 5 km, and occurs at a depth of about 2020?2030 m at the drill site. Changes in conductivity as reflector origin are excluded by investigating the ice-core profile and synthetic RES data. Our observations allow to extrapolate the crystal orientation feature along the reflector in space, with implications for ice-sheet dynamics. As the conductivity profile of the EPICA shows no distinctive peak at this depths, we exclude changes in conductivity as the reflector origin. This is supported by application of numerical forward modelling of electromagnetic wave propagation, based on the conductivity profile, which is able to reproduce nearby reflections, but fails to reproduce this one. Because of background noise, the permittivity profile based on dielectric does not show prominent signals at these depths. We therefore interpret the observed reflector to originate from this change in crystal fabric. Article in Journal/Newspaper Antarc* Antarctica Dronning Maud Land EPICA ice core Ice Sheet The Cryosphere The Cryosphere Discussions Archive ouverte HAL (Hyper Article en Ligne, CCSD - Centre pour la Communication Scientifique Directe) Dronning Maud Land |
institution |
Open Polar |
collection |
Archive ouverte HAL (Hyper Article en Ligne, CCSD - Centre pour la Communication Scientifique Directe) |
op_collection_id |
ftccsdartic |
language |
English |
topic |
[SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces environment [SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere [SDU.STU]Sciences of the Universe [physics]/Earth Sciences |
spellingShingle |
[SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces environment [SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere [SDU.STU]Sciences of the Universe [physics]/Earth Sciences Eisen, O. Hamann, I. Kipfstuhl, S. Steinhage, D. Wilhelms, F. Direct evidence for radar reflector originating from changes in crystal-orientation fabric |
topic_facet |
[SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces environment [SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere [SDU.STU]Sciences of the Universe [physics]/Earth Sciences |
description |
International audience The origin of a strong continuous radar reflector observed with airborne radio-echo sounding (RES) at the EPICA deep-drilling site in Dronning Maud Land, Antarctica, is identified as a transition in crystal fabric orientation from a vertical girdle- to increased single-pole orientation seen along the ice core. The reflector is observed with a 60 ns and 600 ns long pulse at a frequency of 150 MHz, spans one pulse length, is continuous over 5 km, and occurs at a depth of about 2020?2030 m at the drill site. Changes in conductivity as reflector origin are excluded by investigating the ice-core profile and synthetic RES data. Our observations allow to extrapolate the crystal orientation feature along the reflector in space, with implications for ice-sheet dynamics. As the conductivity profile of the EPICA shows no distinctive peak at this depths, we exclude changes in conductivity as the reflector origin. This is supported by application of numerical forward modelling of electromagnetic wave propagation, based on the conductivity profile, which is able to reproduce nearby reflections, but fails to reproduce this one. Because of background noise, the permittivity profile based on dielectric does not show prominent signals at these depths. We therefore interpret the observed reflector to originate from this change in crystal fabric. |
author2 |
Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung = Alfred Wegener Institute for Polar and Marine Research = Institut Alfred-Wegener pour la recherche polaire et marine (AWI) Helmholtz-Gemeinschaft = Helmholtz Association |
format |
Article in Journal/Newspaper |
author |
Eisen, O. Hamann, I. Kipfstuhl, S. Steinhage, D. Wilhelms, F. |
author_facet |
Eisen, O. Hamann, I. Kipfstuhl, S. Steinhage, D. Wilhelms, F. |
author_sort |
Eisen, O. |
title |
Direct evidence for radar reflector originating from changes in crystal-orientation fabric |
title_short |
Direct evidence for radar reflector originating from changes in crystal-orientation fabric |
title_full |
Direct evidence for radar reflector originating from changes in crystal-orientation fabric |
title_fullStr |
Direct evidence for radar reflector originating from changes in crystal-orientation fabric |
title_full_unstemmed |
Direct evidence for radar reflector originating from changes in crystal-orientation fabric |
title_sort |
direct evidence for radar reflector originating from changes in crystal-orientation fabric |
publisher |
HAL CCSD |
publishDate |
2007 |
url |
https://hal.science/hal-00298518 https://hal.science/hal-00298518/document https://hal.science/hal-00298518/file/tcd-1-1-2007.pdf |
geographic |
Dronning Maud Land |
geographic_facet |
Dronning Maud Land |
genre |
Antarc* Antarctica Dronning Maud Land EPICA ice core Ice Sheet The Cryosphere The Cryosphere Discussions |
genre_facet |
Antarc* Antarctica Dronning Maud Land EPICA ice core Ice Sheet The Cryosphere The Cryosphere Discussions |
op_source |
ISSN: 1994-0432 EISSN: 1994-0440 The Cryosphere Discussions https://hal.science/hal-00298518 The Cryosphere Discussions, 2007, 1 (1), pp.1-16 |
op_relation |
hal-00298518 https://hal.science/hal-00298518 https://hal.science/hal-00298518/document https://hal.science/hal-00298518/file/tcd-1-1-2007.pdf |
op_rights |
info:eu-repo/semantics/OpenAccess |
_version_ |
1790594707012714496 |