Low salinity frazil ice generation at the base of a small Antarctic ice shelf
Chemical, isotopic and crystallographic characteristics of marine ice formed at the base of the Hells Gate Ice Shelf, Terra Nova Bay, allow a better understanding of the dynamics of marine ice accretion under small ice shelves. The observed properties of the different types of frazil ice found in th...
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Language: | English |
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Cambridge University Press (CUP)
1993
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Online Access: | http://dx.doi.org/10.1017/s0954102093000409 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0954102093000409 |
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crcambridgeupr:10.1017/s0954102093000409 2024-04-28T07:59:23+00:00 Low salinity frazil ice generation at the base of a small Antarctic ice shelf Tison, J.-L. Ronveaux, D. Lorrain, R. D. 1993 http://dx.doi.org/10.1017/s0954102093000409 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0954102093000409 en eng Cambridge University Press (CUP) https://www.cambridge.org/core/terms Antarctic Science volume 5, issue 3, page 309-322 ISSN 0954-1020 1365-2079 Geology Ecology, Evolution, Behavior and Systematics Oceanography journal-article 1993 crcambridgeupr https://doi.org/10.1017/s0954102093000409 2024-04-09T06:56:07Z Chemical, isotopic and crystallographic characteristics of marine ice formed at the base of the Hells Gate Ice Shelf, Terra Nova Bay, allow a better understanding of the dynamics of marine ice accretion under small ice shelves. The observed properties of the different types of frazil ice found in the area immediately behind the ice shelf front, result from a progressive evolution of the individual frazil ice crystals initially accreted at the base of the ice-shelf. Basal melting caused by the descending plumes of water masses at a temperature above their local freezing point, initiates partial melting of the frazil ice crystals. This dilutes the interstitial water and initiates chemical sorting effects as diffusion proceeds from the normal sea water in the free water column to the diluted interstitial water in the loose frazil layer. Different environmental conditions will result in contrasting properties. Where the subglacial interface is sculptured with domes or inverted channels, it will favour the accumulation of thick units of frazil ice, in a calm environment, that will be further protected from convection mixing over long time periods. This will result in the formation of orbicular frazil showing c-axes at random, strong dilution and important sorting effects. On the contrary, where no channel or dome exist, or where those are already filled with frazil, rectangular or wave-like banded frazil will form with properties showing interfacial streaming effects induced by water currents. Strong c-axes concentration at a single maximum, less dilution and weaker chemical sorting effects are then observed. These findings provide a tentative explanation for the apparent contradiction between the very low salinity levels detected in marine ice at the base of ice shelves and the comparatively minor salinity fluctuations in sea water profiles near ice shelves. Article in Journal/Newspaper Antarc* Antarctic Antarctic Science Ice Shelf Ice Shelves Cambridge University Press Antarctic Science 5 3 309 322 |
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Open Polar |
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Cambridge University Press |
op_collection_id |
crcambridgeupr |
language |
English |
topic |
Geology Ecology, Evolution, Behavior and Systematics Oceanography |
spellingShingle |
Geology Ecology, Evolution, Behavior and Systematics Oceanography Tison, J.-L. Ronveaux, D. Lorrain, R. D. Low salinity frazil ice generation at the base of a small Antarctic ice shelf |
topic_facet |
Geology Ecology, Evolution, Behavior and Systematics Oceanography |
description |
Chemical, isotopic and crystallographic characteristics of marine ice formed at the base of the Hells Gate Ice Shelf, Terra Nova Bay, allow a better understanding of the dynamics of marine ice accretion under small ice shelves. The observed properties of the different types of frazil ice found in the area immediately behind the ice shelf front, result from a progressive evolution of the individual frazil ice crystals initially accreted at the base of the ice-shelf. Basal melting caused by the descending plumes of water masses at a temperature above their local freezing point, initiates partial melting of the frazil ice crystals. This dilutes the interstitial water and initiates chemical sorting effects as diffusion proceeds from the normal sea water in the free water column to the diluted interstitial water in the loose frazil layer. Different environmental conditions will result in contrasting properties. Where the subglacial interface is sculptured with domes or inverted channels, it will favour the accumulation of thick units of frazil ice, in a calm environment, that will be further protected from convection mixing over long time periods. This will result in the formation of orbicular frazil showing c-axes at random, strong dilution and important sorting effects. On the contrary, where no channel or dome exist, or where those are already filled with frazil, rectangular or wave-like banded frazil will form with properties showing interfacial streaming effects induced by water currents. Strong c-axes concentration at a single maximum, less dilution and weaker chemical sorting effects are then observed. These findings provide a tentative explanation for the apparent contradiction between the very low salinity levels detected in marine ice at the base of ice shelves and the comparatively minor salinity fluctuations in sea water profiles near ice shelves. |
format |
Article in Journal/Newspaper |
author |
Tison, J.-L. Ronveaux, D. Lorrain, R. D. |
author_facet |
Tison, J.-L. Ronveaux, D. Lorrain, R. D. |
author_sort |
Tison, J.-L. |
title |
Low salinity frazil ice generation at the base of a small Antarctic ice shelf |
title_short |
Low salinity frazil ice generation at the base of a small Antarctic ice shelf |
title_full |
Low salinity frazil ice generation at the base of a small Antarctic ice shelf |
title_fullStr |
Low salinity frazil ice generation at the base of a small Antarctic ice shelf |
title_full_unstemmed |
Low salinity frazil ice generation at the base of a small Antarctic ice shelf |
title_sort |
low salinity frazil ice generation at the base of a small antarctic ice shelf |
publisher |
Cambridge University Press (CUP) |
publishDate |
1993 |
url |
http://dx.doi.org/10.1017/s0954102093000409 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0954102093000409 |
genre |
Antarc* Antarctic Antarctic Science Ice Shelf Ice Shelves |
genre_facet |
Antarc* Antarctic Antarctic Science Ice Shelf Ice Shelves |
op_source |
Antarctic Science volume 5, issue 3, page 309-322 ISSN 0954-1020 1365-2079 |
op_rights |
https://www.cambridge.org/core/terms |
op_doi |
https://doi.org/10.1017/s0954102093000409 |
container_title |
Antarctic Science |
container_volume |
5 |
container_issue |
3 |
container_start_page |
309 |
op_container_end_page |
322 |
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1797572163692134400 |