Direct Estimate of Lateral Eddy Diffusivity Upstream of Drake Passage
The first direct estimate of the rate at which geostrophic turbulence mixes tracers across the Antarctic Circumpolar Current is presented. The estimate is computed from the spreading of a tracer released upstream of Drake Passage as part of the Diapycnal and Isopycnal Mixing Experiment in the Southe...
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| Format: | Article |
| Language: | en_US |
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American Meteorological Society
2015
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| Online Access: | http://hdl.handle.net/1721.1/95751 https://orcid.org/0000-0002-3736-1956 https://orcid.org/0000-0001-9230-3591 |
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| author | Tulloch, Ross Ferrari, Raffaele Jahn, Oliver Klocker, Andreas Ledwell, James R. Messias, Marie-Jose Speer, Kevin Watson, Andrew LaCasce, Joseph H., 1964- 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 Tulloch, Ross Ferrari, Raffaele Jahn, Oliver Klocker, Andreas Ledwell, James R. Messias, Marie-Jose Speer, Kevin Watson, Andrew LaCasce, Joseph H., 1964- Marshall, John C |
| author_sort | Tulloch, Ross |
| collection | MIT |
| description | The first direct estimate of the rate at which geostrophic turbulence mixes tracers across the Antarctic Circumpolar Current is presented. The estimate is computed from the spreading of a tracer released upstream of Drake Passage as part of the Diapycnal and Isopycnal Mixing Experiment in the Southern Ocean (DIMES). The meridional eddy diffusivity, a measure of the rate at which the area of the tracer spreads along an isopycnal across the Antarctic Circumpolar Current, is 710 ± 260 m[superscript 2] s[superscript −1] at 1500-m depth. The estimate is based on an extrapolation of the tracer-based diffusivity using output from numerical tracers released in a one-twentieth of a degree model simulation of the circulation and turbulence in the Drake Passage region. The model is shown to reproduce the observed spreading rate of the DIMES tracer and suggests that the meridional eddy diffusivity is weak in the upper kilometer of the water column with values below 500 m[superscript 2] s[superscript −1] and peaks at the steering level, near 2 km, where the eddy phase speed is equal to the mean flow speed. These vertical variations are not captured by ocean models presently used for climate studies, but they significantly affect the ventilation of different water masses. |
| first_indexed | 2024-09-23T16:05:45Z |
| format | Article |
| id | mit-1721.1/95751 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T16:05:45Z |
| publishDate | 2015 |
| publisher | American Meteorological Society |
| record_format | dspace |
| spelling | mit-1721.1/957512024-05-15T02:19:41Z Direct Estimate of Lateral Eddy Diffusivity Upstream of Drake Passage Tulloch, Ross Ferrari, Raffaele Jahn, Oliver Klocker, Andreas Ledwell, James R. Messias, Marie-Jose Speer, Kevin Watson, Andrew LaCasce, Joseph H., 1964- Marshall, John C Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences Ferrari, Raffaele Tulloch, Ross Jahn, Oliver Marshall, John C. The first direct estimate of the rate at which geostrophic turbulence mixes tracers across the Antarctic Circumpolar Current is presented. The estimate is computed from the spreading of a tracer released upstream of Drake Passage as part of the Diapycnal and Isopycnal Mixing Experiment in the Southern Ocean (DIMES). The meridional eddy diffusivity, a measure of the rate at which the area of the tracer spreads along an isopycnal across the Antarctic Circumpolar Current, is 710 ± 260 m[superscript 2] s[superscript −1] at 1500-m depth. The estimate is based on an extrapolation of the tracer-based diffusivity using output from numerical tracers released in a one-twentieth of a degree model simulation of the circulation and turbulence in the Drake Passage region. The model is shown to reproduce the observed spreading rate of the DIMES tracer and suggests that the meridional eddy diffusivity is weak in the upper kilometer of the water column with values below 500 m[superscript 2] s[superscript −1] and peaks at the steering level, near 2 km, where the eddy phase speed is equal to the mean flow speed. These vertical variations are not captured by ocean models presently used for climate studies, but they significantly affect the ventilation of different water masses. National Science Foundation (U.S.) (Award OCE-1233832) National Science Foundation (U.S.) (Award OCE-1232962) National Science Foundation (U.S.) (Award OCE-1048926) 2015-03-03T17:24:37Z 2015-03-03T17:24:37Z 2014-12 2014-06 Article http://purl.org/eprint/type/JournalArticle 0022-3670 1520-0485 http://hdl.handle.net/1721.1/95751 Tulloch, Ross, Raffaele Ferrari, Oliver Jahn, Andreas Klocker, Joseph LaCasce, James R. Ledwell, John Marshall, Marie-Jose Messias, Kevin Speer, and Andrew Watson. “Direct Estimate of Lateral Eddy Diffusivity Upstream of Drake Passage.” J. Phys. Oceanogr. 44, no. 10 (October 2014): 2593–2616. © 2014 American Meteorological Society https://orcid.org/0000-0002-3736-1956 https://orcid.org/0000-0001-9230-3591 en_US http://dx.doi.org/10.1175/jpo-d-13-0120.1 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 American Meteorological Society |
| spellingShingle | Tulloch, Ross Ferrari, Raffaele Jahn, Oliver Klocker, Andreas Ledwell, James R. Messias, Marie-Jose Speer, Kevin Watson, Andrew LaCasce, Joseph H., 1964- Marshall, John C Direct Estimate of Lateral Eddy Diffusivity Upstream of Drake Passage |
| title | Direct Estimate of Lateral Eddy Diffusivity Upstream of Drake Passage |
| title_full | Direct Estimate of Lateral Eddy Diffusivity Upstream of Drake Passage |
| title_fullStr | Direct Estimate of Lateral Eddy Diffusivity Upstream of Drake Passage |
| title_full_unstemmed | Direct Estimate of Lateral Eddy Diffusivity Upstream of Drake Passage |
| title_short | Direct Estimate of Lateral Eddy Diffusivity Upstream of Drake Passage |
| title_sort | direct estimate of lateral eddy diffusivity upstream of drake passage |
| url | http://hdl.handle.net/1721.1/95751 https://orcid.org/0000-0002-3736-1956 https://orcid.org/0000-0001-9230-3591 |
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