Direct estimate of lateral eddy diffusivity upstream of Drake Passage
Author Posting. © American Meteorological Society, 2014. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 44 (2014): 2593–2616, doi:10.1175/JPO-D-13-0120.1....
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ftwhoas:oai:darchive.mblwhoilibrary.org:1912/6945 2023-05-15T13:53:15+02:00 Direct estimate of lateral eddy diffusivity upstream of Drake Passage Tulloch, Ross Ferrari, Raffaele Jahn, Oliver Klocker, Andreas LaCasce, Joseph H. Ledwell, James R. Marshall, John C. Messias, Marie-Jose Speer, Kevin G. Watson, Andrew J. 2014-10 application/pdf https://hdl.handle.net/1912/6945 en_US eng American Meteorological Society https://doi.org/ 10.1175/JPO-D-13-0120.1 Journal of Physical Oceanography 44 (2014): 2593–2616 https://hdl.handle.net/1912/6945 doi:10.1175/JPO-D-13-0120.1 Journal of Physical Oceanography 44 (2014): 2593–2616 doi:10.1175/JPO-D-13-0120.1 Geographic location/entity Southern Ocean Circulation/ Dynamics Diffusion Eddies Ocean circulation Turbulence Physical Meteorology and Climatology Isopycnal mixing Article 2014 ftwhoas https://doi.org/10.1175/JPO-D-13-0120.1 2022-05-28T22:59:12Z Author Posting. © American Meteorological Society, 2014. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 44 (2014): 2593–2616, doi:10.1175/JPO-D-13-0120.1. 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 m2 s−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 m2 s−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. NSF support through Awards OCE-1233832, OCE-1232962, and OCE-1048926 is gratefully acknowledged. 2015-04-01 Article in Journal/Newspaper Antarc* Antarctic Drake Passage Southern Ocean Woods Hole Scientific Community: WHOAS (Woods Hole Open Access Server) Antarctic Southern Ocean The Antarctic Drake Passage Journal of Physical Oceanography 44 10 2593 2616 |
institution |
Open Polar |
collection |
Woods Hole Scientific Community: WHOAS (Woods Hole Open Access Server) |
op_collection_id |
ftwhoas |
language |
English |
topic |
Geographic location/entity Southern Ocean Circulation/ Dynamics Diffusion Eddies Ocean circulation Turbulence Physical Meteorology and Climatology Isopycnal mixing |
spellingShingle |
Geographic location/entity Southern Ocean Circulation/ Dynamics Diffusion Eddies Ocean circulation Turbulence Physical Meteorology and Climatology Isopycnal mixing Tulloch, Ross Ferrari, Raffaele Jahn, Oliver Klocker, Andreas LaCasce, Joseph H. Ledwell, James R. Marshall, John C. Messias, Marie-Jose Speer, Kevin G. Watson, Andrew J. Direct estimate of lateral eddy diffusivity upstream of Drake Passage |
topic_facet |
Geographic location/entity Southern Ocean Circulation/ Dynamics Diffusion Eddies Ocean circulation Turbulence Physical Meteorology and Climatology Isopycnal mixing |
description |
Author Posting. © American Meteorological Society, 2014. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 44 (2014): 2593–2616, doi:10.1175/JPO-D-13-0120.1. 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 m2 s−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 m2 s−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. NSF support through Awards OCE-1233832, OCE-1232962, and OCE-1048926 is gratefully acknowledged. 2015-04-01 |
format |
Article in Journal/Newspaper |
author |
Tulloch, Ross Ferrari, Raffaele Jahn, Oliver Klocker, Andreas LaCasce, Joseph H. Ledwell, James R. Marshall, John C. Messias, Marie-Jose Speer, Kevin G. Watson, Andrew J. |
author_facet |
Tulloch, Ross Ferrari, Raffaele Jahn, Oliver Klocker, Andreas LaCasce, Joseph H. Ledwell, James R. Marshall, John C. Messias, Marie-Jose Speer, Kevin G. Watson, Andrew J. |
author_sort |
Tulloch, Ross |
title |
Direct estimate of lateral eddy diffusivity upstream of Drake Passage |
title_short |
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_sort |
direct estimate of lateral eddy diffusivity upstream of drake passage |
publisher |
American Meteorological Society |
publishDate |
2014 |
url |
https://hdl.handle.net/1912/6945 |
geographic |
Antarctic Southern Ocean The Antarctic Drake Passage |
geographic_facet |
Antarctic Southern Ocean The Antarctic Drake Passage |
genre |
Antarc* Antarctic Drake Passage Southern Ocean |
genre_facet |
Antarc* Antarctic Drake Passage Southern Ocean |
op_source |
Journal of Physical Oceanography 44 (2014): 2593–2616 doi:10.1175/JPO-D-13-0120.1 |
op_relation |
https://doi.org/ 10.1175/JPO-D-13-0120.1 Journal of Physical Oceanography 44 (2014): 2593–2616 https://hdl.handle.net/1912/6945 doi:10.1175/JPO-D-13-0120.1 |
op_doi |
https://doi.org/10.1175/JPO-D-13-0120.1 |
container_title |
Journal of Physical Oceanography |
container_volume |
44 |
container_issue |
10 |
container_start_page |
2593 |
op_container_end_page |
2616 |
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1766258252480249856 |