An Idealized Model of Weddell Gyre Export Variability
Recent observations suggest that the export of Antarctic Bottom Water (AABW) from the Weddell Sea has a seasonal cycle in its temperature and salinity that is correlated with annual wind stress variations. This variability has been attributed to annual vertical excursions of the isopycnals in the We...
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ftcaltechauth:oai:authors.library.caltech.edu:47082 2023-05-15T14:04:55+02:00 An Idealized Model of Weddell Gyre Export Variability Su, Zhan Stewart, Andrew L. Thompson, Andrew F. 2014-06 application/pdf https://authors.library.caltech.edu/47082/ https://authors.library.caltech.edu/47082/1/jpo-d-13-0263.1.pdf https://resolver.caltech.edu/CaltechAUTHORS:20140708-150815163 en eng American Meteorological Society https://authors.library.caltech.edu/47082/1/jpo-d-13-0263.1.pdf Su, Zhan and Stewart, Andrew L. and Thompson, Andrew F. (2014) An Idealized Model of Weddell Gyre Export Variability. Journal of Physical Oceanography, 44 (6). pp. 1671-1688. ISSN 0022-3670. doi:10.1175/JPO-D-13-0263.1. https://resolver.caltech.edu/CaltechAUTHORS:20140708-150815163 <https://resolver.caltech.edu/CaltechAUTHORS:20140708-150815163> other Article PeerReviewed 2014 ftcaltechauth https://doi.org/10.1175/JPO-D-13-0263.1 2021-11-11T18:58:33Z Recent observations suggest that the export of Antarctic Bottom Water (AABW) from the Weddell Sea has a seasonal cycle in its temperature and salinity that is correlated with annual wind stress variations. This variability has been attributed to annual vertical excursions of the isopycnals in the Weddell Gyre, modifying the water properties at the depth of the Orkney Passage. Recent studies attribute these variations to locally wind-driven barotropic dynamics in the northern Weddell Sea boundary current. This paper explores an alternative mechanism in which the isopycnals respond directly to surface Ekman pumping, which is coupled to rapidly responding mesoscale eddy buoyancy fluxes near the gyre boundary. A conceptual model of the interface that separates Weddell Sea Deep Water from Circumpolar Deep Water is described in which the bounding isopycnal responds to a seasonal oscillation in the surface wind stress. Different parameterizations of the mesoscale eddy diffusivity are tested. The model accurately predicts the observed phases of the temperature and salinity variability in relationship to the surface wind stress. The model, despite its heavy idealization, also accounts for more than 50% of the observed oscillation amplitude, which depends on the strength of the seasonal wind variability and the parameterized eddy diffusivity. These results highlight the importance of mesoscale eddies in modulating the export of AABW in narrow boundary layers around the Antarctic margins. Article in Journal/Newspaper Antarc* Antarctic Weddell Sea Caltech Authors (California Institute of Technology) Antarctic The Antarctic Weddell Weddell Sea Journal of Physical Oceanography 44 6 1671 1688 |
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Open Polar |
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Caltech Authors (California Institute of Technology) |
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ftcaltechauth |
language |
English |
description |
Recent observations suggest that the export of Antarctic Bottom Water (AABW) from the Weddell Sea has a seasonal cycle in its temperature and salinity that is correlated with annual wind stress variations. This variability has been attributed to annual vertical excursions of the isopycnals in the Weddell Gyre, modifying the water properties at the depth of the Orkney Passage. Recent studies attribute these variations to locally wind-driven barotropic dynamics in the northern Weddell Sea boundary current. This paper explores an alternative mechanism in which the isopycnals respond directly to surface Ekman pumping, which is coupled to rapidly responding mesoscale eddy buoyancy fluxes near the gyre boundary. A conceptual model of the interface that separates Weddell Sea Deep Water from Circumpolar Deep Water is described in which the bounding isopycnal responds to a seasonal oscillation in the surface wind stress. Different parameterizations of the mesoscale eddy diffusivity are tested. The model accurately predicts the observed phases of the temperature and salinity variability in relationship to the surface wind stress. The model, despite its heavy idealization, also accounts for more than 50% of the observed oscillation amplitude, which depends on the strength of the seasonal wind variability and the parameterized eddy diffusivity. These results highlight the importance of mesoscale eddies in modulating the export of AABW in narrow boundary layers around the Antarctic margins. |
format |
Article in Journal/Newspaper |
author |
Su, Zhan Stewart, Andrew L. Thompson, Andrew F. |
spellingShingle |
Su, Zhan Stewart, Andrew L. Thompson, Andrew F. An Idealized Model of Weddell Gyre Export Variability |
author_facet |
Su, Zhan Stewart, Andrew L. Thompson, Andrew F. |
author_sort |
Su, Zhan |
title |
An Idealized Model of Weddell Gyre Export Variability |
title_short |
An Idealized Model of Weddell Gyre Export Variability |
title_full |
An Idealized Model of Weddell Gyre Export Variability |
title_fullStr |
An Idealized Model of Weddell Gyre Export Variability |
title_full_unstemmed |
An Idealized Model of Weddell Gyre Export Variability |
title_sort |
idealized model of weddell gyre export variability |
publisher |
American Meteorological Society |
publishDate |
2014 |
url |
https://authors.library.caltech.edu/47082/ https://authors.library.caltech.edu/47082/1/jpo-d-13-0263.1.pdf https://resolver.caltech.edu/CaltechAUTHORS:20140708-150815163 |
geographic |
Antarctic The Antarctic Weddell Weddell Sea |
geographic_facet |
Antarctic The Antarctic Weddell Weddell Sea |
genre |
Antarc* Antarctic Weddell Sea |
genre_facet |
Antarc* Antarctic Weddell Sea |
op_relation |
https://authors.library.caltech.edu/47082/1/jpo-d-13-0263.1.pdf Su, Zhan and Stewart, Andrew L. and Thompson, Andrew F. (2014) An Idealized Model of Weddell Gyre Export Variability. Journal of Physical Oceanography, 44 (6). pp. 1671-1688. ISSN 0022-3670. doi:10.1175/JPO-D-13-0263.1. https://resolver.caltech.edu/CaltechAUTHORS:20140708-150815163 <https://resolver.caltech.edu/CaltechAUTHORS:20140708-150815163> |
op_rights |
other |
op_doi |
https://doi.org/10.1175/JPO-D-13-0263.1 |
container_title |
Journal of Physical Oceanography |
container_volume |
44 |
container_issue |
6 |
container_start_page |
1671 |
op_container_end_page |
1688 |
_version_ |
1766276377204490240 |