The Dependence of Southern Ocean Meridional Overturning on Wind Stress
An eddy-resolving numerical model of a zonal flow, meant to resemble the Antarctic Circumpolar Current, is described and analyzed using the framework of J. Marshall and T. Radko. In addition to wind and buoyancy forcing at the surface, the model contains a sponge layer at the northern boundary that...
| Main Authors: | , , |
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| Format: | Article |
| Language: | en_US |
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American Meteorological Society
2012
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| Online Access: | http://hdl.handle.net/1721.1/70089 https://orcid.org/0000-0001-9230-3591 |
| _version_ | 1811093977853591552 |
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| author | Abernathey, Ryan Patrick Ferreira, David Marshall, John C |
| author2 | Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences |
| author_facet | Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences Abernathey, Ryan Patrick Ferreira, David Marshall, John C |
| author_sort | Abernathey, Ryan Patrick |
| collection | MIT |
| description | An eddy-resolving numerical model of a zonal flow, meant to resemble the Antarctic Circumpolar Current, is described and analyzed using the framework of J. Marshall and T. Radko. In addition to wind and buoyancy forcing at the surface, the model contains a sponge layer at the northern boundary that permits a residual meridional overturning circulation (MOC) to exist at depth. The strength of the residual MOC is diagnosed for different strengths of surface wind stress. It is found that the eddy circulation largely compensates for the changes in Ekman circulation. The extent of the compensation and thus the sensitivity of the MOC to the winds depend on the surface boundary condition. A fixed-heat-flux surface boundary severely limits the ability of the MOC to change. An interactive heat flux leads to greater sensitivity. To explain the MOC sensitivity to the wind strength under the interactive heat flux, transformed Eulerian-mean theory is applied, in which the eddy diffusivity plays a central role in determining the eddy response. A scaling theory for the eddy diffusivity, based on the mechanical energy balance, is developed and tested; the average magnitude of the diffusivity is found to be proportional to the square root of the wind stress. The MOC sensitivity to the winds based on this scaling is compared with the true sensitivity diagnosed from the experiments. |
| first_indexed | 2024-09-23T15:53:40Z |
| format | Article |
| id | mit-1721.1/70089 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T15:53:40Z |
| publishDate | 2012 |
| publisher | American Meteorological Society |
| record_format | dspace |
| spelling | mit-1721.1/700892024-05-15T05:38:45Z The Dependence of Southern Ocean Meridional Overturning on Wind Stress Abernathey, Ryan Patrick Ferreira, David Marshall, John C Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences Marshall, John C. Abernathey, Ryan Patrick Marshall, John C. Ferreira, David An eddy-resolving numerical model of a zonal flow, meant to resemble the Antarctic Circumpolar Current, is described and analyzed using the framework of J. Marshall and T. Radko. In addition to wind and buoyancy forcing at the surface, the model contains a sponge layer at the northern boundary that permits a residual meridional overturning circulation (MOC) to exist at depth. The strength of the residual MOC is diagnosed for different strengths of surface wind stress. It is found that the eddy circulation largely compensates for the changes in Ekman circulation. The extent of the compensation and thus the sensitivity of the MOC to the winds depend on the surface boundary condition. A fixed-heat-flux surface boundary severely limits the ability of the MOC to change. An interactive heat flux leads to greater sensitivity. To explain the MOC sensitivity to the wind strength under the interactive heat flux, transformed Eulerian-mean theory is applied, in which the eddy diffusivity plays a central role in determining the eddy response. A scaling theory for the eddy diffusivity, based on the mechanical energy balance, is developed and tested; the average magnitude of the diffusivity is found to be proportional to the square root of the wind stress. The MOC sensitivity to the winds based on this scaling is compared with the true sensitivity diagnosed from the experiments. National Science Foundation (U.S.) 2012-04-20T17:33:36Z 2012-04-20T17:33:36Z 2011-12 2011-01 Article http://purl.org/eprint/type/JournalArticle 0022-3670 1520-0485 http://hdl.handle.net/1721.1/70089 Abernathey, Ryan, John Marshall, and David Ferreira. “The Dependence of Southern Ocean Meridional Overturning on Wind Stress.” Journal of Physical Oceanography 41.12 (2011): 2261–2278. Web. 20 Apr. 2012. © 2011 American Meteorological Society https://orcid.org/0000-0001-9230-3591 en_US http://dx.doi.org/10.1175/jpo-d-11-023.1 Journal of Physical Oceanography Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. application/pdf American Meteorological Society APS |
| spellingShingle | Abernathey, Ryan Patrick Ferreira, David Marshall, John C The Dependence of Southern Ocean Meridional Overturning on Wind Stress |
| title | The Dependence of Southern Ocean Meridional Overturning on Wind Stress |
| title_full | The Dependence of Southern Ocean Meridional Overturning on Wind Stress |
| title_fullStr | The Dependence of Southern Ocean Meridional Overturning on Wind Stress |
| title_full_unstemmed | The Dependence of Southern Ocean Meridional Overturning on Wind Stress |
| title_short | The Dependence of Southern Ocean Meridional Overturning on Wind Stress |
| title_sort | dependence of southern ocean meridional overturning on wind stress |
| url | http://hdl.handle.net/1721.1/70089 https://orcid.org/0000-0001-9230-3591 |
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