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Short-circuiting of the oceanic overturning circulation in the Antarctic Circumpolar Current

Short-circuiting of the oceanic overturning circulation in the Antarctic Circumpolar Current
Short-circuiting of the oceanic overturning circulation in the Antarctic Circumpolar Current
The oceanic overturning circulation has a central role in the Earth's climate system and in biogeochemical cycling as it transports heat, carbon and nutrients around the globe and regulates their storage in the deep ocean. Mixing processes in the Antarctic Circumpolar Current are key to this circulation, because they control the rate at which water sinking at high latitudes returns to the surface in the Southern Ocean. Yet estimates of the rates of these processes and of the upwelling that they induce are poorly constrained by observations. Here we take advantage of a natural tracer-release experiment—an injection of mantle helium from hydrothermal vents into the Circumpolar Current near Drake Passage9—to measure the rates of mixing and upwelling in the current's intermediate layers over a sector that spans nearly one-tenth of its circumpolar path. Dispersion of the tracer reveals rapid upwelling along density surfaces and intense mixing across density surfaces, both occurring at rates that are an order of magnitude greater than rates implicit in models of the average Southern Ocean overturning. These findings support the view that deep-water pathways along and across density surfaces intensify and intertwine as the Antarctic Circumpolar Current flows over complex ocean-floor topography, giving rise to a short circuit of the overturning circulation in these regions.
0028-0836
194-197
Naveira Garabato, Alberto C.
97c0e923-f076-4b38-b89b-938e11cea7a6
Stevens, David P.
80cd1121-2231-443b-a5e2-32235739fca0
Watson, Andrew J.
55e619df-85a4-4079-922b-8cb1f17290a8
Roether, Watson
29cc1b60-707e-46d7-8f82-e8e8253cb5a5
Roether, Wolfgang
a473e51f-6875-4ab2-8cf9-e0dbc8c115f6
Naveira Garabato, Alberto C.
97c0e923-f076-4b38-b89b-938e11cea7a6
Stevens, David P.
80cd1121-2231-443b-a5e2-32235739fca0
Watson, Andrew J.
55e619df-85a4-4079-922b-8cb1f17290a8
Roether, Watson
29cc1b60-707e-46d7-8f82-e8e8253cb5a5
Roether, Wolfgang
a473e51f-6875-4ab2-8cf9-e0dbc8c115f6

Naveira Garabato, Alberto C., Stevens, David P., Watson, Andrew J., Roether, Watson and Roether, Wolfgang (2007) Short-circuiting of the oceanic overturning circulation in the Antarctic Circumpolar Current. Nature, 447 (7141), 194-197. (doi:10.1038/nature05832).

Record type: Article

Abstract

The oceanic overturning circulation has a central role in the Earth's climate system and in biogeochemical cycling as it transports heat, carbon and nutrients around the globe and regulates their storage in the deep ocean. Mixing processes in the Antarctic Circumpolar Current are key to this circulation, because they control the rate at which water sinking at high latitudes returns to the surface in the Southern Ocean. Yet estimates of the rates of these processes and of the upwelling that they induce are poorly constrained by observations. Here we take advantage of a natural tracer-release experiment—an injection of mantle helium from hydrothermal vents into the Circumpolar Current near Drake Passage9—to measure the rates of mixing and upwelling in the current's intermediate layers over a sector that spans nearly one-tenth of its circumpolar path. Dispersion of the tracer reveals rapid upwelling along density surfaces and intense mixing across density surfaces, both occurring at rates that are an order of magnitude greater than rates implicit in models of the average Southern Ocean overturning. These findings support the view that deep-water pathways along and across density surfaces intensify and intertwine as the Antarctic Circumpolar Current flows over complex ocean-floor topography, giving rise to a short circuit of the overturning circulation in these regions.

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More information

Published date: 2007
Additional Information: Published in 'Letters' section of Nature

Identifiers

Local EPrints ID: 42476
URI: http://eprints.soton.ac.uk/id/eprint/42476
ISSN: 0028-0836
PURE UUID: d0fb9014-49d5-4f3d-9640-78b75d299707
ORCID for Alberto C. Naveira Garabato: ORCID iD orcid.org/0000-0001-6071-605X

Catalogue record

Date deposited: 13 Dec 2006
Last modified: 16 Mar 2024 03:48

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Contributors

Author: David P. Stevens
Author: Andrew J. Watson
Author: Watson Roether
Author: Wolfgang Roether

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