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

Meredith, Michael P. ORCID: https://orcid.org/0000-0002-7342-7756; Brown, Peter J.; Naveira Garabato, Alberto C.; Jullion, Loïc; Venables, Hugh J. ORCID: https://orcid.org/0000-0002-6445-8462; Messias, Marie-José. 2013 Dense bottom layers in the Scotia Sea, Southern Ocean: Creation, lifespan, and destruction. Geophysical Research Letters, 40 (5). 933-936. 10.1002/grl.50260

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Official URL: http://dx.doi.org/10.1002/grl.50260

Abstract/Summary

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.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	10.1002/grl.50260
Programmes:	BAS Programmes > Polar Science for Planet Earth (2009 - ) > Polar Oceans
ISSN:	00948276
Additional Keywords:	Dense bottom layers, Abyssal mixing, Southern Ocean, Overflows
Date made live:	25 Apr 2013 08:34 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/501484

Item Type:

Publication - Article

Digital Object Identifier (DOI):

10.1002/grl.50260

Programmes:

BAS Programmes > Polar Science for Planet Earth (2009 - ) > Polar Oceans

ISSN:

00948276

Additional Keywords:

Dense bottom layers, Abyssal mixing, Southern Ocean, Overflows

Date made live:

25 Apr 2013 08:34 +0 (UTC)