Eddy stirring in the Southern Ocean
There is an ongoing debate concerning the distribution of eddy stirring across the Antarctic Circumpolar Current (ACC) and the nature of its controlling processes. The problem is addressed here by estimating the isentropic eddy diffusivity Kappa from a collection of hydrographic and altimetric obser...
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| Other Authors: | |
| Format: | Article |
| Language: | en_US |
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American Geophysical Union (AGU)
2012
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| Online Access: | http://hdl.handle.net/1721.1/73684 https://orcid.org/0000-0002-3736-1956 |
| _version_ | 1826196075616141312 |
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| author | Ferrari, Raffaele Garabato, Alberto C. Naveira Polzin, K. L. |
| 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 Ferrari, Raffaele Garabato, Alberto C. Naveira Polzin, K. L. |
| author_sort | Ferrari, Raffaele |
| collection | MIT |
| description | There is an ongoing debate concerning the distribution of eddy stirring across the Antarctic Circumpolar Current (ACC) and the nature of its controlling processes. The problem is addressed here by estimating the isentropic eddy diffusivity Kappa from a collection of hydrographic and altimetric observations, analyzed in a mixing length theoretical framework. It is shown that, typically, Kappa is suppressed by an order of magnitude in the upper kilometer of the ACC frontal jets relative to their surroundings, primarily as a result of a local reduction of the mixing length. This observation is reproduced by a quasi-geostrophic theory of eddy stirring across a broad barotropic jet based on the scaling law derived by Ferrari and Nikurashin (2010). The theory interprets the observed widespread suppression of the mixing length and Kappa in the upper layers of frontal jets as the kinematic consequence of eddy propagation relative to the mean flow within jet cores. Deviations from the prevalent regime of mixing suppression in the core of upper-ocean jets are encountered in a few special sites. Such ‘leaky jet’ segments appear to be associated with sharp stationary meanders of the mean flow that are generated by the interaction of the ACC with major topographic features. It is contended that the characteristic thermohaline structure of the Southern Ocean, consisting of multiple upper-ocean thermohaline fronts separated and underlaid by regions of homogenized properties, is largely a result of the widespread suppression of eddy stirring by parallel jets. |
| first_indexed | 2024-09-23T10:20:27Z |
| format | Article |
| id | mit-1721.1/73684 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T10:20:27Z |
| publishDate | 2012 |
| publisher | American Geophysical Union (AGU) |
| record_format | dspace |
| spelling | mit-1721.1/736842022-09-30T20:29:40Z Eddy stirring in the Southern Ocean Ferrari, Raffaele Garabato, Alberto C. Naveira Polzin, K. L. Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences Ferrari, Raffaele There is an ongoing debate concerning the distribution of eddy stirring across the Antarctic Circumpolar Current (ACC) and the nature of its controlling processes. The problem is addressed here by estimating the isentropic eddy diffusivity Kappa from a collection of hydrographic and altimetric observations, analyzed in a mixing length theoretical framework. It is shown that, typically, Kappa is suppressed by an order of magnitude in the upper kilometer of the ACC frontal jets relative to their surroundings, primarily as a result of a local reduction of the mixing length. This observation is reproduced by a quasi-geostrophic theory of eddy stirring across a broad barotropic jet based on the scaling law derived by Ferrari and Nikurashin (2010). The theory interprets the observed widespread suppression of the mixing length and Kappa in the upper layers of frontal jets as the kinematic consequence of eddy propagation relative to the mean flow within jet cores. Deviations from the prevalent regime of mixing suppression in the core of upper-ocean jets are encountered in a few special sites. Such ‘leaky jet’ segments appear to be associated with sharp stationary meanders of the mean flow that are generated by the interaction of the ACC with major topographic features. It is contended that the characteristic thermohaline structure of the Southern Ocean, consisting of multiple upper-ocean thermohaline fronts separated and underlaid by regions of homogenized properties, is largely a result of the widespread suppression of eddy stirring by parallel jets. National Science Foundation (U.S.) (Award OCE‐0825376) 2012-10-09T16:20:10Z 2012-10-09T16:20:10Z 2011-09 2011-06 Article http://purl.org/eprint/type/JournalArticle 0148-0227 http://hdl.handle.net/1721.1/73684 Naveira Garabato, A. C., R. Ferrari, and K. L. Polzin. “Eddy Stirring in the Southern Ocean.” Journal of Geophysical Research 116.C9 (2011). ©2011 American Geophysical Union https://orcid.org/0000-0002-3736-1956 en_US http://dx.doi.org/10.1029/2010jc006818 Journal of Geophysical Research 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 Geophysical Union (AGU) MIT web domain |
| spellingShingle | Ferrari, Raffaele Garabato, Alberto C. Naveira Polzin, K. L. Eddy stirring in the Southern Ocean |
| title | Eddy stirring in the Southern Ocean |
| title_full | Eddy stirring in the Southern Ocean |
| title_fullStr | Eddy stirring in the Southern Ocean |
| title_full_unstemmed | Eddy stirring in the Southern Ocean |
| title_short | Eddy stirring in the Southern Ocean |
| title_sort | eddy stirring in the southern ocean |
| url | http://hdl.handle.net/1721.1/73684 https://orcid.org/0000-0002-3736-1956 |
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