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Letter. Slowing of the Atlantic meridional overturning circulation at 25° N

Letter. Slowing of the Atlantic meridional overturning circulation at 25° N
Letter. Slowing of the Atlantic meridional overturning circulation at 25° N
The Atlantic meridional overturning circulation carries warm upper waters into far-northern latitudes and returns cold deep waters southward across the Equator. Its heat transport makes a substantial contribution to the moderate climate of maritime and continental Europe, and any slowdown in the overturning circulation would have profound implications for climate change. A transatlantic section along latitude 25° N has been used as a baseline for estimating the overturning circulation and associated heat transport. Here we analyse a new 25° N transatlantic section and compare it with four previous sections taken over the past five decades. The comparison suggests that the Atlantic meridional overturning circulation has slowed by about 30 per cent between 1957 and 2004. Whereas the northward transport in the Gulf Stream across 25° N has remained nearly constant, the slowing is evident both in a 50 per cent larger southward-moving mid-ocean recirculation of thermocline waters, and also in a 50 per cent decrease in the southward transport of lower North Atlantic Deep Water between 3,000 and 5,000 m in depth. In 2004, more of the northward Gulf Stream flow was recirculating back southward in the thermocline within the subtropical gyre, and less was returning southward at depth.
gulf stream, ocean circulation, north atlantic current, climatic changes
0028-0836
655-657
Bryden, H.L.
7f823946-34e8-48a3-8bd4-a72d2d749184
Longworth, H.R.
e7983a34-ecc2-4897-b110-236ac7f54f43
Cunningham, S.A.
07f1bd78-d92f-478b-a016-b92f530142c3
Bryden, H.L.
7f823946-34e8-48a3-8bd4-a72d2d749184
Longworth, H.R.
e7983a34-ecc2-4897-b110-236ac7f54f43
Cunningham, S.A.
07f1bd78-d92f-478b-a016-b92f530142c3

Bryden, H.L., Longworth, H.R. and Cunningham, S.A. (2005) Letter. Slowing of the Atlantic meridional overturning circulation at 25° N. Nature, 438 (7068), 655-657. (doi:10.1038/nature04385).

Record type: Article

Abstract

The Atlantic meridional overturning circulation carries warm upper waters into far-northern latitudes and returns cold deep waters southward across the Equator. Its heat transport makes a substantial contribution to the moderate climate of maritime and continental Europe, and any slowdown in the overturning circulation would have profound implications for climate change. A transatlantic section along latitude 25° N has been used as a baseline for estimating the overturning circulation and associated heat transport. Here we analyse a new 25° N transatlantic section and compare it with four previous sections taken over the past five decades. The comparison suggests that the Atlantic meridional overturning circulation has slowed by about 30 per cent between 1957 and 2004. Whereas the northward transport in the Gulf Stream across 25° N has remained nearly constant, the slowing is evident both in a 50 per cent larger southward-moving mid-ocean recirculation of thermocline waters, and also in a 50 per cent decrease in the southward transport of lower North Atlantic Deep Water between 3,000 and 5,000 m in depth. In 2004, more of the northward Gulf Stream flow was recirculating back southward in the thermocline within the subtropical gyre, and less was returning southward at depth.

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Published date: 2005
Keywords: gulf stream, ocean circulation, north atlantic current, climatic changes

Identifiers

Local EPrints ID: 19134
URI: https://eprints.soton.ac.uk/id/eprint/19134
ISSN: 0028-0836
PURE UUID: 74491cc6-c71f-4ad8-b39d-35fbd003946f
ORCID for H.L. Bryden: ORCID iD orcid.org/0000-0002-8216-6359

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Date deposited: 03 Jan 2006
Last modified: 06 Jun 2018 13:02

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Author: H.L. Bryden ORCID iD
Author: H.R. Longworth
Author: S.A. Cunningham

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