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Dense bottom layers in the Scotia Sea, Southern Ocean: Creation, lifespan, and destruction

Dense bottom layers in the Scotia Sea, Southern Ocean: Creation, lifespan, and destruction
Dense bottom layers in the Scotia Sea, Southern Ocean: Creation, lifespan, and destruction
The lower limb of the Atlantic overturning circulation is renewed by dense waters from the Southern Ocean, a substantial portion of which flow through the Scotia Sea. We report dense bottom layers here, with gradients in temperature and salinity comparable to those seen near the surface of the Southern Ocean. These are overlain by layers with much weaker stratification, and are caused by episodic overflows of dense waters across the South Scotia Ridge, and topographic trapping within deep trenches. One such layer was found to be at least 3–4 years older than the water immediately above. The estimated vertical diffusivity to which this layer was subject is substantially less than the strong basin-average deep mixing reported previously. We conjecture that (a) vertical mixing in the Scotia Sea is strongly spatially inhomogeneous, and (b) the flushing of these layers, like their formation, is related to overflow events, and hence also strongly episodic.
Dense bottom layers, Abyssal mixing, Southern Ocean, Overflows
0094-8276
933-936
Meredith, Michael P.
25fd5f1c-f3ed-40a2-af59-5a7074a25fcd
Brown, Peter J.
29f4e81e-e0c4-4147-984b-0215571fb2ca
Naveira Garabato, Alberto C.
97c0e923-f076-4b38-b89b-938e11cea7a6
Jullion, Loïc
e72025ed-bc3d-4c9f-a78e-4b41cb1c6da9
Venables, Hugh J.
076cfe85-e2f9-4e69-8793-0ab225e7fadd
Messias, Marie-José
024b3503-8bfc-4e1d-aeeb-6c8ed0d6830b
Meredith, Michael P.
25fd5f1c-f3ed-40a2-af59-5a7074a25fcd
Brown, Peter J.
29f4e81e-e0c4-4147-984b-0215571fb2ca
Naveira Garabato, Alberto C.
97c0e923-f076-4b38-b89b-938e11cea7a6
Jullion, Loïc
e72025ed-bc3d-4c9f-a78e-4b41cb1c6da9
Venables, Hugh J.
076cfe85-e2f9-4e69-8793-0ab225e7fadd
Messias, Marie-José
024b3503-8bfc-4e1d-aeeb-6c8ed0d6830b

Meredith, Michael P., Brown, Peter J., Naveira Garabato, Alberto C., Jullion, Loïc, Venables, Hugh J. and Messias, Marie-José (2013) Dense bottom layers in the Scotia Sea, Southern Ocean: Creation, lifespan, and destruction. Geophysical Research Letters, 40 (5), 933-936. (doi:10.1002/grl.50260).

Record type: Article

Abstract

The lower limb of the Atlantic overturning circulation is renewed by dense waters from the Southern Ocean, a substantial portion of which flow through the Scotia Sea. We report dense bottom layers here, with gradients in temperature and salinity comparable to those seen near the surface of the Southern Ocean. These are overlain by layers with much weaker stratification, and are caused by episodic overflows of dense waters across the South Scotia Ridge, and topographic trapping within deep trenches. One such layer was found to be at least 3–4 years older than the water immediately above. The estimated vertical diffusivity to which this layer was subject is substantially less than the strong basin-average deep mixing reported previously. We conjecture that (a) vertical mixing in the Scotia Sea is strongly spatially inhomogeneous, and (b) the flushing of these layers, like their formation, is related to overflow events, and hence also strongly episodic.

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More information

Published date: 16 March 2013
Keywords: Dense bottom layers, Abyssal mixing, Southern Ocean, Overflows
Organisations: Physical Oceanography

Identifiers

Local EPrints ID: 351854
URI: http://eprints.soton.ac.uk/id/eprint/351854
ISSN: 0094-8276
PURE UUID: 935fa51d-b2f4-494c-8a35-a7ed5b20071b
ORCID for Alberto C. Naveira Garabato: ORCID iD orcid.org/0000-0001-6071-605X

Catalogue record

Date deposited: 25 Apr 2013 10:53
Last modified: 15 Mar 2024 03:24

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Contributors

Author: Michael P. Meredith
Author: Peter J. Brown
Author: Loïc Jullion
Author: Hugh J. Venables
Author: Marie-José Messias

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