Temporal evolution of decaying summer first-year sea ice in the Western Weddell Sea, Antarctica
The evolution of the main physico-chemical properties of the unflooded 90-cm-thick first-year sea-ice cover at the Ice Station POLarstern (ISPOL) "clean site" is described. ISPOL was an international experiment of the German research icebreaker R.V. Polarstern. The vessel was anchored to a...
Published in: | Deep Sea Research Part II: Topical Studies in Oceanography |
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Format: | Article in Journal/Newspaper |
Language: | English |
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2008
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ftvliz:oai:oma.vliz.be:210808 2023-05-15T13:33:16+02:00 Temporal evolution of decaying summer first-year sea ice in the Western Weddell Sea, Antarctica Tison, J.L. Worby, A. Delille, B. Brabant, F. Papadimitriou, S. Thomas, D. de Jong, J. Lannuzel, D. Haas, C. 2008 http://www.vliz.be/nl/open-marien-archief?module=ref&refid=210808 en eng info:eu-repo/semantics/altIdentifier/wos/000257303200006 info:eu-repo/semantics/altIdentifier/doi/doi.org/10.1016/j.dsr2.2007.12.021 http://www.vliz.be/nl/open-marien-archief?module=ref&refid=210808 info:eu-repo/semantics/restrictedAccess %3Ci%3EDeep-Sea+Res.,+Part+II,+Top.+Stud.+Oceanogr.+55%288-9%29%3C%2Fi%3E%3A+975-987.+%3Ca+href%3D%22https%3A%2F%2Fdx.doi.org%2F10.1016%2Fj.dsr2.2007.12.021%22+target%3D%22_blank%22%3Ehttps%3A%2F%2Fdx.doi.org%2F10.1016%2Fj.dsr2.2007.12.021%3C%2Fa%3E info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion 2008 ftvliz https://doi.org/10.1016/j.dsr2.2007.12.021 2022-05-01T09:37:42Z The evolution of the main physico-chemical properties of the unflooded 90-cm-thick first-year sea-ice cover at the Ice Station POLarstern (ISPOL) "clean site" is described. ISPOL was an international experiment of the German research icebreaker R.V. Polarstern. The vessel was anchored to an ice floe for an observation period of 5 weeks, during the early summer melt onset in the Western Weddell Sea. The "clean site" was specially designed and accessed so as to prevent any trace metal contamination of the sampling area. Observations were made at 5-day intervals during December 2004 in the central part of the main floe. Results show the succession of two contrasting phases in the behavior of the brine network (brine channels, pockets, and tubes). Initially, brine salinity was higher than that of sea-water, leading to brine migration and a decrease in the mean bulk salinity of the ice cover. This process is highly favored by the already high bulk porosity (14%), which ensures full connectivity of the brine network. Gravity drainage rather than convection seems to be the dominant brine transfer process. Half-way through the observation period, the brine salinity became lower than that of the sea-water throughout the ice column. The brine network therefore switched to a "stratified" regime in which exchange with sea-water was limited to molecular diffusion, strongly stabilizing the bulk mean sea-ice salinity. During the transition between the two regimes, and in areas closer to ridges, slush water (resulting from a mixture of snow meltwater and sea water accumulated at the snow-ice interface) penetrated through the growing "honeycomb-like structure" and replaced the downward draining brines. This resulted in a slight local replenishment of nutrients (as indicated by dissolved silicic acid). However, as a whole, the described decaying regime in this globally unflooded location with limited snow cover should be unfavorable to the development of healthy and active surface and internal microbial communities. The switch from gravity to diffusion controlled transport mechanisms within the ice column also should affect the efficiency of gas exchange across the sea-ice cover. The observed late build-up of a continuous, impermeable, superimposed ice layer should further significantly hamper gas exchange. Statistical estimates of the evolution of the ice thickness during the observation period and salinity trends of the under-ice water salinity down to 30m corroborate model predictions of a moderate bottom melting (5-10cm) from ocean heat fluxes. Article in Journal/Newspaper Antarc* Antarctica Sea ice Weddell Sea Flanders Marine Institute (VLIZ): Open Marine Archive (OMA) Weddell Sea Weddell Deep Sea Research Part II: Topical Studies in Oceanography 55 8-9 975 987 |
institution |
Open Polar |
collection |
Flanders Marine Institute (VLIZ): Open Marine Archive (OMA) |
op_collection_id |
ftvliz |
language |
English |
description |
The evolution of the main physico-chemical properties of the unflooded 90-cm-thick first-year sea-ice cover at the Ice Station POLarstern (ISPOL) "clean site" is described. ISPOL was an international experiment of the German research icebreaker R.V. Polarstern. The vessel was anchored to an ice floe for an observation period of 5 weeks, during the early summer melt onset in the Western Weddell Sea. The "clean site" was specially designed and accessed so as to prevent any trace metal contamination of the sampling area. Observations were made at 5-day intervals during December 2004 in the central part of the main floe. Results show the succession of two contrasting phases in the behavior of the brine network (brine channels, pockets, and tubes). Initially, brine salinity was higher than that of sea-water, leading to brine migration and a decrease in the mean bulk salinity of the ice cover. This process is highly favored by the already high bulk porosity (14%), which ensures full connectivity of the brine network. Gravity drainage rather than convection seems to be the dominant brine transfer process. Half-way through the observation period, the brine salinity became lower than that of the sea-water throughout the ice column. The brine network therefore switched to a "stratified" regime in which exchange with sea-water was limited to molecular diffusion, strongly stabilizing the bulk mean sea-ice salinity. During the transition between the two regimes, and in areas closer to ridges, slush water (resulting from a mixture of snow meltwater and sea water accumulated at the snow-ice interface) penetrated through the growing "honeycomb-like structure" and replaced the downward draining brines. This resulted in a slight local replenishment of nutrients (as indicated by dissolved silicic acid). However, as a whole, the described decaying regime in this globally unflooded location with limited snow cover should be unfavorable to the development of healthy and active surface and internal microbial communities. The switch from gravity to diffusion controlled transport mechanisms within the ice column also should affect the efficiency of gas exchange across the sea-ice cover. The observed late build-up of a continuous, impermeable, superimposed ice layer should further significantly hamper gas exchange. Statistical estimates of the evolution of the ice thickness during the observation period and salinity trends of the under-ice water salinity down to 30m corroborate model predictions of a moderate bottom melting (5-10cm) from ocean heat fluxes. |
format |
Article in Journal/Newspaper |
author |
Tison, J.L. Worby, A. Delille, B. Brabant, F. Papadimitriou, S. Thomas, D. de Jong, J. Lannuzel, D. Haas, C. |
spellingShingle |
Tison, J.L. Worby, A. Delille, B. Brabant, F. Papadimitriou, S. Thomas, D. de Jong, J. Lannuzel, D. Haas, C. Temporal evolution of decaying summer first-year sea ice in the Western Weddell Sea, Antarctica |
author_facet |
Tison, J.L. Worby, A. Delille, B. Brabant, F. Papadimitriou, S. Thomas, D. de Jong, J. Lannuzel, D. Haas, C. |
author_sort |
Tison, J.L. |
title |
Temporal evolution of decaying summer first-year sea ice in the Western Weddell Sea, Antarctica |
title_short |
Temporal evolution of decaying summer first-year sea ice in the Western Weddell Sea, Antarctica |
title_full |
Temporal evolution of decaying summer first-year sea ice in the Western Weddell Sea, Antarctica |
title_fullStr |
Temporal evolution of decaying summer first-year sea ice in the Western Weddell Sea, Antarctica |
title_full_unstemmed |
Temporal evolution of decaying summer first-year sea ice in the Western Weddell Sea, Antarctica |
title_sort |
temporal evolution of decaying summer first-year sea ice in the western weddell sea, antarctica |
publishDate |
2008 |
url |
http://www.vliz.be/nl/open-marien-archief?module=ref&refid=210808 |
geographic |
Weddell Sea Weddell |
geographic_facet |
Weddell Sea Weddell |
genre |
Antarc* Antarctica Sea ice Weddell Sea |
genre_facet |
Antarc* Antarctica Sea ice Weddell Sea |
op_source |
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op_relation |
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op_rights |
info:eu-repo/semantics/restrictedAccess |
op_doi |
https://doi.org/10.1016/j.dsr2.2007.12.021 |
container_title |
Deep Sea Research Part II: Topical Studies in Oceanography |
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55 |
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8-9 |
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