Modification of the deep salinity-maximum in the Southern Ocean by circulation in the Antarctic Circumpolar Current and the Weddell Gyre
The evolution of the deep salinity-maximum associated with the Lower Circumpolar Deep Water (LCDW) is assessed using a set of 37 hydrographic sections collected over a 20 year period in the Southern Ocean as part of the WOCE/CLIVAR programme. A circumpolar decrease in the value of the salinity maxim...
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ftnerc:oai:nora.nerc.ac.uk:516836 2023-05-15T13:49:34+02:00 Modification of the deep salinity-maximum in the Southern Ocean by circulation in the Antarctic Circumpolar Current and the Weddell Gyre Donnelly, M.S. Leach, H. Strass, V. 2017-07 text http://nora.nerc.ac.uk/id/eprint/516836/ https://nora.nerc.ac.uk/id/eprint/516836/1/ODYN-D-15-00095_R4.pdf en eng https://nora.nerc.ac.uk/id/eprint/516836/1/ODYN-D-15-00095_R4.pdf Donnelly, M.S.; Leach, H.; Strass, V. 2017 Modification of the deep salinity-maximum in the Southern Ocean by circulation in the Antarctic Circumpolar Current and the Weddell Gyre. Ocean Dynamics, 67 (7). 813-838. Publication - Article PeerReviewed 2017 ftnerc 2023-02-04T19:44:50Z The evolution of the deep salinity-maximum associated with the Lower Circumpolar Deep Water (LCDW) is assessed using a set of 37 hydrographic sections collected over a 20 year period in the Southern Ocean as part of the WOCE/CLIVAR programme. A circumpolar decrease in the value of the salinity maximum is observed eastwards from the North Atlantic Deep Water (NADW) in the Atlantic sector of the Southern Ocean through the Indian and Pacific sectors to Drake Passage. Isopycnal mixing processes are limited by circumpolar fronts, and in the Atlantic sector this acts to limit the direct poleward propagation of the salinity signal. Limited entrainment occurs into the Weddell Gyre, with LCDW entering primarily through the eddydominated eastern limb. A vertical mixing coefficient, κV of (2.86 ± 1.06) x 10^-4 m^2 s^-1 and an isopycnal mixing coefficient, κI of (8.97 ± 1.67) x 10^2 m^2 s^-1 are calculated for the eastern Indian and Pacific sectors of the Antarctic Circumpolar Current (ACC). A κV of (2.39 ± 2.83) x 10-5 m^2 s^-1, an order of magnitude smaller, and a κI of (2.47 ± 0.63) x 10^2 m^2 s^-1, three times smaller, are calculated for the southern and eastern Weddell Gyre reflecting a more turbulent regime in the ACC and a less turbulent regime in the Weddell Gyre. In agreement with other studies, we conclude that the ACC acts as a barrier to direct meridional transport and mixing in the Atlantic sector evidenced by the eastward propagation of the deep salinity-maximum signal, insulating the Weddell Gyre from short-term changes in NADW characteristics. Article in Journal/Newspaper Antarc* Antarctic Drake Passage NADW North Atlantic Deep Water North Atlantic Southern Ocean Natural Environment Research Council: NERC Open Research Archive Antarctic Southern Ocean The Antarctic Drake Passage Pacific Indian Weddell |
institution |
Open Polar |
collection |
Natural Environment Research Council: NERC Open Research Archive |
op_collection_id |
ftnerc |
language |
English |
description |
The evolution of the deep salinity-maximum associated with the Lower Circumpolar Deep Water (LCDW) is assessed using a set of 37 hydrographic sections collected over a 20 year period in the Southern Ocean as part of the WOCE/CLIVAR programme. A circumpolar decrease in the value of the salinity maximum is observed eastwards from the North Atlantic Deep Water (NADW) in the Atlantic sector of the Southern Ocean through the Indian and Pacific sectors to Drake Passage. Isopycnal mixing processes are limited by circumpolar fronts, and in the Atlantic sector this acts to limit the direct poleward propagation of the salinity signal. Limited entrainment occurs into the Weddell Gyre, with LCDW entering primarily through the eddydominated eastern limb. A vertical mixing coefficient, κV of (2.86 ± 1.06) x 10^-4 m^2 s^-1 and an isopycnal mixing coefficient, κI of (8.97 ± 1.67) x 10^2 m^2 s^-1 are calculated for the eastern Indian and Pacific sectors of the Antarctic Circumpolar Current (ACC). A κV of (2.39 ± 2.83) x 10-5 m^2 s^-1, an order of magnitude smaller, and a κI of (2.47 ± 0.63) x 10^2 m^2 s^-1, three times smaller, are calculated for the southern and eastern Weddell Gyre reflecting a more turbulent regime in the ACC and a less turbulent regime in the Weddell Gyre. In agreement with other studies, we conclude that the ACC acts as a barrier to direct meridional transport and mixing in the Atlantic sector evidenced by the eastward propagation of the deep salinity-maximum signal, insulating the Weddell Gyre from short-term changes in NADW characteristics. |
format |
Article in Journal/Newspaper |
author |
Donnelly, M.S. Leach, H. Strass, V. |
spellingShingle |
Donnelly, M.S. Leach, H. Strass, V. Modification of the deep salinity-maximum in the Southern Ocean by circulation in the Antarctic Circumpolar Current and the Weddell Gyre |
author_facet |
Donnelly, M.S. Leach, H. Strass, V. |
author_sort |
Donnelly, M.S. |
title |
Modification of the deep salinity-maximum in the Southern Ocean by circulation in the Antarctic Circumpolar Current and the Weddell Gyre |
title_short |
Modification of the deep salinity-maximum in the Southern Ocean by circulation in the Antarctic Circumpolar Current and the Weddell Gyre |
title_full |
Modification of the deep salinity-maximum in the Southern Ocean by circulation in the Antarctic Circumpolar Current and the Weddell Gyre |
title_fullStr |
Modification of the deep salinity-maximum in the Southern Ocean by circulation in the Antarctic Circumpolar Current and the Weddell Gyre |
title_full_unstemmed |
Modification of the deep salinity-maximum in the Southern Ocean by circulation in the Antarctic Circumpolar Current and the Weddell Gyre |
title_sort |
modification of the deep salinity-maximum in the southern ocean by circulation in the antarctic circumpolar current and the weddell gyre |
publishDate |
2017 |
url |
http://nora.nerc.ac.uk/id/eprint/516836/ https://nora.nerc.ac.uk/id/eprint/516836/1/ODYN-D-15-00095_R4.pdf |
geographic |
Antarctic Southern Ocean The Antarctic Drake Passage Pacific Indian Weddell |
geographic_facet |
Antarctic Southern Ocean The Antarctic Drake Passage Pacific Indian Weddell |
genre |
Antarc* Antarctic Drake Passage NADW North Atlantic Deep Water North Atlantic Southern Ocean |
genre_facet |
Antarc* Antarctic Drake Passage NADW North Atlantic Deep Water North Atlantic Southern Ocean |
op_relation |
https://nora.nerc.ac.uk/id/eprint/516836/1/ODYN-D-15-00095_R4.pdf Donnelly, M.S.; Leach, H.; Strass, V. 2017 Modification of the deep salinity-maximum in the Southern Ocean by circulation in the Antarctic Circumpolar Current and the Weddell Gyre. Ocean Dynamics, 67 (7). 813-838. |
_version_ |
1766251658209132544 |