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 an ice floe f...
Published in: | Deep Sea Research Part II: Topical Studies in Oceanography |
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Online Access: | https://doi.org/10.1016/j.dsr2.2007.12.021 http://ecite.utas.edu.au/71382 |
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ftunivtasecite:oai:ecite.utas.edu.au:71382 2023-05-15T14:02:30+02:00 Temporal evolution of decaying summer first-year sea ice in the Western Weddell Sea, Antarctica Tison, JL Worby, AP Delille, B Brabant, F Papadimitriou, S Thomas, D de Jong, J Lannuzel, D Haas, C 2008 https://doi.org/10.1016/j.dsr2.2007.12.021 http://ecite.utas.edu.au/71382 en eng Pergamon-Elsevier Science Ltd http://dx.doi.org/10.1016/j.dsr2.2007.12.021 Tison, JL and Worby, AP and Delille, B and Brabant, F and Papadimitriou, S and Thomas, D and de Jong, J and Lannuzel, D and Haas, C, Temporal evolution of decaying summer first-year sea ice in the Western Weddell Sea, Antarctica, Deep-Sea Research. Part 2: Topical Studies in Oceanography, 55, (8-9) pp. 975-987. ISSN 0967-0645 (2008) [Refereed Article] http://ecite.utas.edu.au/71382 Earth Sciences Oceanography Physical Oceanography Refereed Article PeerReviewed 2008 ftunivtasecite https://doi.org/10.1016/j.dsr2.2007.12.021 2019-12-13T21:38:51Z 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 snowice 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 30 m corroborate model predictions of a moderate bottom melting (510 cm) from ocean heat fluxes. Article in Journal/Newspaper Antarc* Antarctica Sea ice Weddell Sea eCite UTAS (University of Tasmania) Weddell Weddell Sea Deep Sea Research Part II: Topical Studies in Oceanography 55 8-9 975 987 |
institution |
Open Polar |
collection |
eCite UTAS (University of Tasmania) |
op_collection_id |
ftunivtasecite |
language |
English |
topic |
Earth Sciences Oceanography Physical Oceanography |
spellingShingle |
Earth Sciences Oceanography Physical Oceanography Tison, JL Worby, AP 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 |
topic_facet |
Earth Sciences Oceanography Physical Oceanography |
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 snowice 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 30 m corroborate model predictions of a moderate bottom melting (510 cm) from ocean heat fluxes. |
format |
Article in Journal/Newspaper |
author |
Tison, JL Worby, AP Delille, B Brabant, F Papadimitriou, S Thomas, D de Jong, J Lannuzel, D Haas, C |
author_facet |
Tison, JL Worby, AP Delille, B Brabant, F Papadimitriou, S Thomas, D de Jong, J Lannuzel, D Haas, C |
author_sort |
Tison, JL |
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 |
publisher |
Pergamon-Elsevier Science Ltd |
publishDate |
2008 |
url |
https://doi.org/10.1016/j.dsr2.2007.12.021 http://ecite.utas.edu.au/71382 |
geographic |
Weddell Weddell Sea |
geographic_facet |
Weddell Weddell Sea |
genre |
Antarc* Antarctica Sea ice Weddell Sea |
genre_facet |
Antarc* Antarctica Sea ice Weddell Sea |
op_relation |
http://dx.doi.org/10.1016/j.dsr2.2007.12.021 Tison, JL and Worby, AP and Delille, B and Brabant, F and Papadimitriou, S and Thomas, D and de Jong, J and Lannuzel, D and Haas, C, Temporal evolution of decaying summer first-year sea ice in the Western Weddell Sea, Antarctica, Deep-Sea Research. Part 2: Topical Studies in Oceanography, 55, (8-9) pp. 975-987. ISSN 0967-0645 (2008) [Refereed Article] http://ecite.utas.edu.au/71382 |
op_doi |
https://doi.org/10.1016/j.dsr2.2007.12.021 |
container_title |
Deep Sea Research Part II: Topical Studies in Oceanography |
container_volume |
55 |
container_issue |
8-9 |
container_start_page |
975 |
op_container_end_page |
987 |
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1766272770168061952 |