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Turbulence and Diapycnal Mixing in Drake Passage

Turbulence and Diapycnal Mixing in Drake Passage
Turbulence and Diapycnal Mixing in Drake Passage
Direct measurements of turbulence levels in the Drake Passage region of the Southern Ocean show a marked enhancement over the Phoenix Ridge. At this site, the Antarctic Circumpolar Current (ACC) is constricted in its flow between the southern tip of South America and the northern tip of the Antarctic Peninsula. Observed turbulent kinetic energy dissipation rates are enhanced in the regions corresponding to the ACC frontal zones where strong flow reaches the bottom. In these areas, turbulent dissipation levels reach 10?8 W kg?1 at abyssal and middepths. The mixing enhancement in the frontal regions is sufficient to elevate the diapycnal turbulent diffusivity acting in the deep water above the axis of the ridge to 1 × 10?4 m2 s?1. This level is an order of magnitude larger than the mixing levels observed upstream in the ACC above smoother bathymetry. Outside of the frontal regions, dissipation rates are O(10?10) W kg?1, comparable to the background levels of turbulence found throughout most mid- and low-latitude regions of the global ocean.
Southern Ocean, Turbulence, Diapycnal mixing
0022-3670
2143-2152
St. Laurent, L.
745fc400-a419-4bce-859b-89e63b0cd80d
Naveira Garabato, A.C.
97c0e923-f076-4b38-b89b-938e11cea7a6
Ledwell, J.R.
d80aab8b-3022-425a-9b89-7dd329ae464d
Thurnherr, A.M.
7b1feb8a-78a2-48b5-9b68-152ada222636
Toole, J.M.
4c567d7c-a1b4-4d5b-a76d-0f70c28a614f
Watson, A.J.
22b78032-6022-4ed3-bea8-d1bfefcf599c
St. Laurent, L.
745fc400-a419-4bce-859b-89e63b0cd80d
Naveira Garabato, A.C.
97c0e923-f076-4b38-b89b-938e11cea7a6
Ledwell, J.R.
d80aab8b-3022-425a-9b89-7dd329ae464d
Thurnherr, A.M.
7b1feb8a-78a2-48b5-9b68-152ada222636
Toole, J.M.
4c567d7c-a1b4-4d5b-a76d-0f70c28a614f
Watson, A.J.
22b78032-6022-4ed3-bea8-d1bfefcf599c

St. Laurent, L., Naveira Garabato, A.C., Ledwell, J.R., Thurnherr, A.M., Toole, J.M. and Watson, A.J. (2012) Turbulence and Diapycnal Mixing in Drake Passage. Journal of Physical Oceanography, 42 (12), 2143-2152. (doi:10.1175/JPO-D-12-027.1).

Record type: Article

Abstract

Direct measurements of turbulence levels in the Drake Passage region of the Southern Ocean show a marked enhancement over the Phoenix Ridge. At this site, the Antarctic Circumpolar Current (ACC) is constricted in its flow between the southern tip of South America and the northern tip of the Antarctic Peninsula. Observed turbulent kinetic energy dissipation rates are enhanced in the regions corresponding to the ACC frontal zones where strong flow reaches the bottom. In these areas, turbulent dissipation levels reach 10?8 W kg?1 at abyssal and middepths. The mixing enhancement in the frontal regions is sufficient to elevate the diapycnal turbulent diffusivity acting in the deep water above the axis of the ridge to 1 × 10?4 m2 s?1. This level is an order of magnitude larger than the mixing levels observed upstream in the ACC above smoother bathymetry. Outside of the frontal regions, dissipation rates are O(10?10) W kg?1, comparable to the background levels of turbulence found throughout most mid- and low-latitude regions of the global ocean.

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Published date: 2012
Keywords: Southern Ocean, Turbulence, Diapycnal mixing
Organisations: Physical Oceanography

Identifiers

Local EPrints ID: 347640
URI: https://eprints.soton.ac.uk/id/eprint/347640
ISSN: 0022-3670
PURE UUID: 8ccab7ea-35df-4bb2-93a9-9bf68c60e818

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Date deposited: 28 Jan 2013 11:49
Last modified: 03 Oct 2017 16:40

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Contributors

Author: L. St. Laurent
Author: J.R. Ledwell
Author: A.M. Thurnherr
Author: J.M. Toole
Author: A.J. Watson

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