Open-ocean convection and polynya formation in a large-scale ice-ocean model
The physical processes responsible for the formation in a large-scale ice ocean model of an offshore polynya near the Greenwich meridian in the Southern Ocean are analysed. In this area, the brine release during ice formation in autumn is sufficient to destabilise the water column and trigger convec...
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ftunistlouisbrus:oai:dial.uclouvain.be:boreal:42927 2024-05-12T07:53:11+00:00 Open-ocean convection and polynya formation in a large-scale ice-ocean model Goosse, Hugues Fichefet, Thierry UCL - SC/PHYS - Département de physique UCL - SST/ELI/ELIC - Earth & Climate 2001 http://hdl.handle.net/2078.1/42927 https://doi.org/10.1034/j.1600-0870.2001.01061.x eng eng Munksgaard Int Publ Ltd boreal:42927 http://hdl.handle.net/2078.1/42927 doi:10.1034/j.1600-0870.2001.01061.x urn:ISSN:0280-6495 urn:EISSN:1600-0870 info:eu-repo/semantics/openAccess Tellus. Series A: Dynamic Meteorology and Oceanography, Vol. 53, no. 1, p. 94-111 (2001) info:eu-repo/semantics/article 2001 ftunistlouisbrus https://doi.org/10.1034/j.1600-0870.2001.01061.x 2024-04-18T18:14:15Z The physical processes responsible for the formation in a large-scale ice ocean model of an offshore polynya near the Greenwich meridian in the Southern Ocean are analysed. In this area, the brine release during ice formation in autumn is sufficient to destabilise the water column and trigger convection. This incorporates relatively warm water into the surface layer which, in a first step, slows down ice formation. In a second step, it gives rise to ice melting until the total disappearance of the ice at the end of September. Two elements are crucial for the polynya opening. The first one is a strong ice-transport divergence in fall induced by southeasterly winds, which enhances the amount of local ice formation and thus of brine release. The second is an inflow of relatively warm water at depth originating from the Antarctic Circumpolar Current, that sustains the intense vertical heat flux in the ocean during convection. The simulated polynya occurs in a region where such features have been frequently observed. Nevertheless. the model polynya is too wide and persistent. In addition, it develops each year, contrary to observations. The use of a climatological forcing with no interannual variability is the major cause of these deficiencies, the simulated too low density in the deep Southern Ocean and the coarse resolution of the model playing also a role. a passive tracer released in the polynya area indicates that the water mass produced there contributes significantly to the renewal of deep water in the Weddell Gyre and that it is a major component of the Antarctic Bottom Water (AABW) inflow into the model Atlantic. Article in Journal/Newspaper Antarc* Antarctic Southern Ocean DIAL@USL-B (Université Saint-Louis, Bruxelles) Antarctic Southern Ocean The Antarctic Weddell Greenwich Tellus A 53 1 94 111 |
institution |
Open Polar |
collection |
DIAL@USL-B (Université Saint-Louis, Bruxelles) |
op_collection_id |
ftunistlouisbrus |
language |
English |
description |
The physical processes responsible for the formation in a large-scale ice ocean model of an offshore polynya near the Greenwich meridian in the Southern Ocean are analysed. In this area, the brine release during ice formation in autumn is sufficient to destabilise the water column and trigger convection. This incorporates relatively warm water into the surface layer which, in a first step, slows down ice formation. In a second step, it gives rise to ice melting until the total disappearance of the ice at the end of September. Two elements are crucial for the polynya opening. The first one is a strong ice-transport divergence in fall induced by southeasterly winds, which enhances the amount of local ice formation and thus of brine release. The second is an inflow of relatively warm water at depth originating from the Antarctic Circumpolar Current, that sustains the intense vertical heat flux in the ocean during convection. The simulated polynya occurs in a region where such features have been frequently observed. Nevertheless. the model polynya is too wide and persistent. In addition, it develops each year, contrary to observations. The use of a climatological forcing with no interannual variability is the major cause of these deficiencies, the simulated too low density in the deep Southern Ocean and the coarse resolution of the model playing also a role. a passive tracer released in the polynya area indicates that the water mass produced there contributes significantly to the renewal of deep water in the Weddell Gyre and that it is a major component of the Antarctic Bottom Water (AABW) inflow into the model Atlantic. |
author2 |
UCL - SC/PHYS - Département de physique UCL - SST/ELI/ELIC - Earth & Climate |
format |
Article in Journal/Newspaper |
author |
Goosse, Hugues Fichefet, Thierry |
spellingShingle |
Goosse, Hugues Fichefet, Thierry Open-ocean convection and polynya formation in a large-scale ice-ocean model |
author_facet |
Goosse, Hugues Fichefet, Thierry |
author_sort |
Goosse, Hugues |
title |
Open-ocean convection and polynya formation in a large-scale ice-ocean model |
title_short |
Open-ocean convection and polynya formation in a large-scale ice-ocean model |
title_full |
Open-ocean convection and polynya formation in a large-scale ice-ocean model |
title_fullStr |
Open-ocean convection and polynya formation in a large-scale ice-ocean model |
title_full_unstemmed |
Open-ocean convection and polynya formation in a large-scale ice-ocean model |
title_sort |
open-ocean convection and polynya formation in a large-scale ice-ocean model |
publisher |
Munksgaard Int Publ Ltd |
publishDate |
2001 |
url |
http://hdl.handle.net/2078.1/42927 https://doi.org/10.1034/j.1600-0870.2001.01061.x |
geographic |
Antarctic Southern Ocean The Antarctic Weddell Greenwich |
geographic_facet |
Antarctic Southern Ocean The Antarctic Weddell Greenwich |
genre |
Antarc* Antarctic Southern Ocean |
genre_facet |
Antarc* Antarctic Southern Ocean |
op_source |
Tellus. Series A: Dynamic Meteorology and Oceanography, Vol. 53, no. 1, p. 94-111 (2001) |
op_relation |
boreal:42927 http://hdl.handle.net/2078.1/42927 doi:10.1034/j.1600-0870.2001.01061.x urn:ISSN:0280-6495 urn:EISSN:1600-0870 |
op_rights |
info:eu-repo/semantics/openAccess |
op_doi |
https://doi.org/10.1034/j.1600-0870.2001.01061.x |
container_title |
Tellus A |
container_volume |
53 |
container_issue |
1 |
container_start_page |
94 |
op_container_end_page |
111 |
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1798841364909129728 |