Electrical resistivity of George VI Ice Shelf, Antarctic Peninsula
A georesistivity survey was made on part of George VI Ice Shelf (71°55'S, 67°20'W). The principal objectives were to determine the electrical structure of the 1ce shelf, in particular how refrozen melt water differs in electrical behaviour from dry firn, and to Investigate the environment...
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International Glaciological Society
1982
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Online Access: | http://nora.nerc.ac.uk/id/eprint/524462/ https://doi.org/10.3189/S0260305500002925 |
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ftnerc:oai:nora.nerc.ac.uk:524462 2023-05-15T13:29:18+02:00 Electrical resistivity of George VI Ice Shelf, Antarctic Peninsula Reynolds, John M. 1982 http://nora.nerc.ac.uk/id/eprint/524462/ https://doi.org/10.3189/S0260305500002925 unknown International Glaciological Society Reynolds, John M. 1982 Electrical resistivity of George VI Ice Shelf, Antarctic Peninsula. Annals of Glaciology, 3. 279-283. https://doi.org/10.3189/S0260305500002925 <https://doi.org/10.3189/S0260305500002925> Publication - Article PeerReviewed 1982 ftnerc https://doi.org/10.3189/S0260305500002925 2023-02-04T19:48:53Z A georesistivity survey was made on part of George VI Ice Shelf (71°55'S, 67°20'W). The principal objectives were to determine the electrical structure of the 1ce shelf, in particular how refrozen melt water differs in electrical behaviour from dry firn, and to Investigate the environment beneath the ice shelf. Apparent resistivity profiles using a Schlumberger electrode configuration have been interpreted using Ghosh's convolution method for vertical electrical sounding (VES), adapted for use where extreme resistivity contrasts are present. Warm, wet surface conditions tend to reduce the gross resistivity of shallow permeable layers. The electrical results indicate that the refrozen free water has affected the resistivity only indirectly; the mean density of firn is raised to about 0.915 Mg m−3 within the uppermost 10 m of the ice shelf at which point the resistivity is comparable to that of Ice of the same density but formed by compaction of firn. The apparent resistivities in the top 100 m reflect the variation of density with depth; a small range of resistivities implies that the range of density 1s narrow and that densification is affected by the percolation and refreezing of melt water. The bulk of the ice behaves as if resistivity either Is independent of temperature or has only a slight dependence (activation energy ~0.15 eV) with a basal melting rate in excess of 1 to 2 m a−1. The principal resistivities determined for two sites on George VI Ice Shelf were within 10% of those at station BC on the Ross Ice Shelf, allowing for differences in temperature. This Indicates that polar ice, I.e. non-temperate ice, has a very narrow range of resistivity. The apparent resistivity profiles are consistent with there being sea-water of oceanic salinity under the Ice shelf. Article in Journal/Newspaper Annals of Glaciology Antarc* Antarctic Antarctic Peninsula George VI Ice Shelf Ice Shelf Ross Ice Shelf Natural Environment Research Council: NERC Open Research Archive Antarctic Antarctic Peninsula Ross Ice Shelf George VI Ice Shelf ENVELOPE(-67.840,-67.840,-71.692,-71.692) Annals of Glaciology 3 279 283 |
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Open Polar |
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Natural Environment Research Council: NERC Open Research Archive |
op_collection_id |
ftnerc |
language |
unknown |
description |
A georesistivity survey was made on part of George VI Ice Shelf (71°55'S, 67°20'W). The principal objectives were to determine the electrical structure of the 1ce shelf, in particular how refrozen melt water differs in electrical behaviour from dry firn, and to Investigate the environment beneath the ice shelf. Apparent resistivity profiles using a Schlumberger electrode configuration have been interpreted using Ghosh's convolution method for vertical electrical sounding (VES), adapted for use where extreme resistivity contrasts are present. Warm, wet surface conditions tend to reduce the gross resistivity of shallow permeable layers. The electrical results indicate that the refrozen free water has affected the resistivity only indirectly; the mean density of firn is raised to about 0.915 Mg m−3 within the uppermost 10 m of the ice shelf at which point the resistivity is comparable to that of Ice of the same density but formed by compaction of firn. The apparent resistivities in the top 100 m reflect the variation of density with depth; a small range of resistivities implies that the range of density 1s narrow and that densification is affected by the percolation and refreezing of melt water. The bulk of the ice behaves as if resistivity either Is independent of temperature or has only a slight dependence (activation energy ~0.15 eV) with a basal melting rate in excess of 1 to 2 m a−1. The principal resistivities determined for two sites on George VI Ice Shelf were within 10% of those at station BC on the Ross Ice Shelf, allowing for differences in temperature. This Indicates that polar ice, I.e. non-temperate ice, has a very narrow range of resistivity. The apparent resistivity profiles are consistent with there being sea-water of oceanic salinity under the Ice shelf. |
format |
Article in Journal/Newspaper |
author |
Reynolds, John M. |
spellingShingle |
Reynolds, John M. Electrical resistivity of George VI Ice Shelf, Antarctic Peninsula |
author_facet |
Reynolds, John M. |
author_sort |
Reynolds, John M. |
title |
Electrical resistivity of George VI Ice Shelf, Antarctic Peninsula |
title_short |
Electrical resistivity of George VI Ice Shelf, Antarctic Peninsula |
title_full |
Electrical resistivity of George VI Ice Shelf, Antarctic Peninsula |
title_fullStr |
Electrical resistivity of George VI Ice Shelf, Antarctic Peninsula |
title_full_unstemmed |
Electrical resistivity of George VI Ice Shelf, Antarctic Peninsula |
title_sort |
electrical resistivity of george vi ice shelf, antarctic peninsula |
publisher |
International Glaciological Society |
publishDate |
1982 |
url |
http://nora.nerc.ac.uk/id/eprint/524462/ https://doi.org/10.3189/S0260305500002925 |
long_lat |
ENVELOPE(-67.840,-67.840,-71.692,-71.692) |
geographic |
Antarctic Antarctic Peninsula Ross Ice Shelf George VI Ice Shelf |
geographic_facet |
Antarctic Antarctic Peninsula Ross Ice Shelf George VI Ice Shelf |
genre |
Annals of Glaciology Antarc* Antarctic Antarctic Peninsula George VI Ice Shelf Ice Shelf Ross Ice Shelf |
genre_facet |
Annals of Glaciology Antarc* Antarctic Antarctic Peninsula George VI Ice Shelf Ice Shelf Ross Ice Shelf |
op_relation |
Reynolds, John M. 1982 Electrical resistivity of George VI Ice Shelf, Antarctic Peninsula. Annals of Glaciology, 3. 279-283. https://doi.org/10.3189/S0260305500002925 <https://doi.org/10.3189/S0260305500002925> |
op_doi |
https://doi.org/10.3189/S0260305500002925 |
container_title |
Annals of Glaciology |
container_volume |
3 |
container_start_page |
279 |
op_container_end_page |
283 |
_version_ |
1765999845107040256 |