Boundary mixing in Orkney Passage outflow
Author Posting. © American Geophysical Union, 2014. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Oceans 119 (2014): 8627–8645, doi:10.1002/2014JC010099. One o...
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ftwhoas:oai:darchive.mblwhoilibrary.org:1912/7170 2023-05-15T13:53:15+02:00 Boundary mixing in Orkney Passage outflow Polzin, Kurt L. Naveira Garabato, Alberto C. Abrahamsen, E. Povl Jullion, Loic Meredith, Michael P. 2014-12-16 application/pdf https://hdl.handle.net/1912/7170 en_US eng John Wiley & Sons https://doi.org/10.1002/2014JC010099 Journal of Geophysical Research: Oceans 119 (2014): 8627–8645 https://hdl.handle.net/1912/7170 doi:10.1002/2014JC010099 Journal of Geophysical Research: Oceans 119 (2014): 8627–8645 doi:10.1002/2014JC010099 Mixing Transport Control volume Article 2014 ftwhoas https://doi.org/10.1002/2014JC010099 2022-05-28T22:59:16Z Author Posting. © American Geophysical Union, 2014. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Oceans 119 (2014): 8627–8645, doi:10.1002/2014JC010099. One of the most remarkable features of contemporary oceanic climate change is the warming and contraction of Antarctic Bottom Water over much of global ocean abyss. These signatures represent changes in ventilation mediated by mixing and entrainment processes that may be location-specific. Here we use available data to document, as best possible, those mixing processes as Weddell Sea Deep and Bottom Waters flow along the South Orkney Plateau, exit the Weddell Sea via Orkney Passage and fill the abyssal Scotia Sea. First, we find that an abrupt transition in topography upstream of Orkney Passage delimits the extent of the coldest waters along the Plateau's flanks and may indicate a region of especially intense mixing. Second, we revisit a control volume budget by Heywood et al. (2002) for waters trapped within the Scotia Sea after entering through Orkney Passage. This budget requires extremely vigorous water mass transformations with a diapycnal transfer coefficient of inline image m2 s−1. Evidence for such intense diapycnal mixing is not found in the abyssal Scotia Sea interior and, while we do find large rates of diapycnal mixing in conjunction with a downwelling Ekman layer on the western side of Orkney Passage, it is insufficient to close the budget. This leads us to hypothesize that the Heywood budget is closed by a boundary mixing process in which the Ekman layer associated with the Weddell Sea Deep Water boundary current experiences relatively large vertical scale overturning associated with tidal forcing along the southern boundary of the Scotia Sea. KLP gratefully acknowledges salary support from Woods Hole Oceanographic Institution bridge support funds. ACNG acknowledges the support of a Philip Leverhulme ... Article in Journal/Newspaper Antarc* Antarctic Scotia Sea Weddell Sea Woods Hole Scientific Community: WHOAS (Woods Hole Open Access Server) Antarctic Weddell Sea Scotia Sea Weddell Heywood ENVELOPE(-59.683,-59.683,-62.317,-62.317) South Orkney Plateau ENVELOPE(-44.157,-44.157,-60.690,-60.690) Journal of Geophysical Research: Oceans 119 12 8627 8645 |
institution |
Open Polar |
collection |
Woods Hole Scientific Community: WHOAS (Woods Hole Open Access Server) |
op_collection_id |
ftwhoas |
language |
English |
topic |
Mixing Transport Control volume |
spellingShingle |
Mixing Transport Control volume Polzin, Kurt L. Naveira Garabato, Alberto C. Abrahamsen, E. Povl Jullion, Loic Meredith, Michael P. Boundary mixing in Orkney Passage outflow |
topic_facet |
Mixing Transport Control volume |
description |
Author Posting. © American Geophysical Union, 2014. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Oceans 119 (2014): 8627–8645, doi:10.1002/2014JC010099. One of the most remarkable features of contemporary oceanic climate change is the warming and contraction of Antarctic Bottom Water over much of global ocean abyss. These signatures represent changes in ventilation mediated by mixing and entrainment processes that may be location-specific. Here we use available data to document, as best possible, those mixing processes as Weddell Sea Deep and Bottom Waters flow along the South Orkney Plateau, exit the Weddell Sea via Orkney Passage and fill the abyssal Scotia Sea. First, we find that an abrupt transition in topography upstream of Orkney Passage delimits the extent of the coldest waters along the Plateau's flanks and may indicate a region of especially intense mixing. Second, we revisit a control volume budget by Heywood et al. (2002) for waters trapped within the Scotia Sea after entering through Orkney Passage. This budget requires extremely vigorous water mass transformations with a diapycnal transfer coefficient of inline image m2 s−1. Evidence for such intense diapycnal mixing is not found in the abyssal Scotia Sea interior and, while we do find large rates of diapycnal mixing in conjunction with a downwelling Ekman layer on the western side of Orkney Passage, it is insufficient to close the budget. This leads us to hypothesize that the Heywood budget is closed by a boundary mixing process in which the Ekman layer associated with the Weddell Sea Deep Water boundary current experiences relatively large vertical scale overturning associated with tidal forcing along the southern boundary of the Scotia Sea. KLP gratefully acknowledges salary support from Woods Hole Oceanographic Institution bridge support funds. ACNG acknowledges the support of a Philip Leverhulme ... |
format |
Article in Journal/Newspaper |
author |
Polzin, Kurt L. Naveira Garabato, Alberto C. Abrahamsen, E. Povl Jullion, Loic Meredith, Michael P. |
author_facet |
Polzin, Kurt L. Naveira Garabato, Alberto C. Abrahamsen, E. Povl Jullion, Loic Meredith, Michael P. |
author_sort |
Polzin, Kurt L. |
title |
Boundary mixing in Orkney Passage outflow |
title_short |
Boundary mixing in Orkney Passage outflow |
title_full |
Boundary mixing in Orkney Passage outflow |
title_fullStr |
Boundary mixing in Orkney Passage outflow |
title_full_unstemmed |
Boundary mixing in Orkney Passage outflow |
title_sort |
boundary mixing in orkney passage outflow |
publisher |
John Wiley & Sons |
publishDate |
2014 |
url |
https://hdl.handle.net/1912/7170 |
long_lat |
ENVELOPE(-59.683,-59.683,-62.317,-62.317) ENVELOPE(-44.157,-44.157,-60.690,-60.690) |
geographic |
Antarctic Weddell Sea Scotia Sea Weddell Heywood South Orkney Plateau |
geographic_facet |
Antarctic Weddell Sea Scotia Sea Weddell Heywood South Orkney Plateau |
genre |
Antarc* Antarctic Scotia Sea Weddell Sea |
genre_facet |
Antarc* Antarctic Scotia Sea Weddell Sea |
op_source |
Journal of Geophysical Research: Oceans 119 (2014): 8627–8645 doi:10.1002/2014JC010099 |
op_relation |
https://doi.org/10.1002/2014JC010099 Journal of Geophysical Research: Oceans 119 (2014): 8627–8645 https://hdl.handle.net/1912/7170 doi:10.1002/2014JC010099 |
op_doi |
https://doi.org/10.1002/2014JC010099 |
container_title |
Journal of Geophysical Research: Oceans |
container_volume |
119 |
container_issue |
12 |
container_start_page |
8627 |
op_container_end_page |
8645 |
_version_ |
1766258254845837312 |