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Reduction in ocean heat transport at 26°N since 2008 cools the Eastern Subpolar Gyre of the North Atlantic Ocean

Reduction in ocean heat transport at 26°N since 2008 cools the Eastern Subpolar Gyre of the North Atlantic Ocean
Reduction in ocean heat transport at 26°N since 2008 cools the Eastern Subpolar Gyre of the North Atlantic Ocean
Northward ocean heat transport at 26°N in the Atlantic Ocean has been measured since 2004. The ocean heat transport is large—approximately 1.25 PW, and on interannual time scales it exhibits surprisingly large temporal variability. There has been a long-term reduction in ocean heat transport of 0.17 PW from 1.32 PW before 2009 to 1.15 PW after 2009 (2009–16) on an annual average basis associated with a 2.5-Sv (1 Sv ≡ 106 m3 s−1) drop in the Atlantic meridional overturning circulation (AMOC). The reduction in the AMOC has cooled and freshened the upper ocean north of 26°N over an area following the offshore edge of the Gulf Stream/North Atlantic Current from the Bahamas to Iceland. Cooling peaks south of Iceland where surface temperatures are as much as 2°C cooler in 2016 than they were in 2008. Heat uptake by the atmosphere appears to have been affected particularly along the path of the North Atlantic Current. For the reduction in ocean heat transport, changes in ocean heat content account for about one-quarter of the long-term reduction in ocean heat transport while reduced heat uptake by the atmosphere appears to account for the remainder of the change in ocean heat transport.
0894-8755
1677-1689
Bryden, Harry L.
7f823946-34e8-48a3-8bd4-a72d2d749184
Johns, William E.
e09ba73d-f275-4ff3-a07c-dfb8f1622b21
King, Brian A.
960f44b4-cc9c-4f77-b3c8-775530ac0061
Mccarthy, Gerard
fd87927d-feb3-447a-9cda-9558916df99f
Mcdonagh, Elaine L.
47e26eeb-b774-4068-af07-31847e42b977
Moat, Ben I.
9cb7be4b-9e0e-42cc-a015-bf8dfa5ef27d
Smeed, David A.
2f7e2df1-c899-4d7a-94ef-d47ddb1cc494
Bryden, Harry L.
7f823946-34e8-48a3-8bd4-a72d2d749184
Johns, William E.
e09ba73d-f275-4ff3-a07c-dfb8f1622b21
King, Brian A.
960f44b4-cc9c-4f77-b3c8-775530ac0061
Mccarthy, Gerard
fd87927d-feb3-447a-9cda-9558916df99f
Mcdonagh, Elaine L.
47e26eeb-b774-4068-af07-31847e42b977
Moat, Ben I.
9cb7be4b-9e0e-42cc-a015-bf8dfa5ef27d
Smeed, David A.
2f7e2df1-c899-4d7a-94ef-d47ddb1cc494

Bryden, Harry L., Johns, William E., King, Brian A., Mccarthy, Gerard, Mcdonagh, Elaine L., Moat, Ben I. and Smeed, David A. (2020) Reduction in ocean heat transport at 26°N since 2008 cools the Eastern Subpolar Gyre of the North Atlantic Ocean. Journal of Climate, 33 (5), 1677-1689. (doi:10.1175/JCLI-D-19-0323.1).

Record type: Article

Abstract

Northward ocean heat transport at 26°N in the Atlantic Ocean has been measured since 2004. The ocean heat transport is large—approximately 1.25 PW, and on interannual time scales it exhibits surprisingly large temporal variability. There has been a long-term reduction in ocean heat transport of 0.17 PW from 1.32 PW before 2009 to 1.15 PW after 2009 (2009–16) on an annual average basis associated with a 2.5-Sv (1 Sv ≡ 106 m3 s−1) drop in the Atlantic meridional overturning circulation (AMOC). The reduction in the AMOC has cooled and freshened the upper ocean north of 26°N over an area following the offshore edge of the Gulf Stream/North Atlantic Current from the Bahamas to Iceland. Cooling peaks south of Iceland where surface temperatures are as much as 2°C cooler in 2016 than they were in 2008. Heat uptake by the atmosphere appears to have been affected particularly along the path of the North Atlantic Current. For the reduction in ocean heat transport, changes in ocean heat content account for about one-quarter of the long-term reduction in ocean heat transport while reduced heat uptake by the atmosphere appears to account for the remainder of the change in ocean heat transport.

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Accepted/In Press date: 15 November 2019
e-pub ahead of print date: 24 January 2020
Published date: 1 March 2020

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Local EPrints ID: 438015
URI: http://eprints.soton.ac.uk/id/eprint/438015
ISSN: 0894-8755
PURE UUID: e7de4b74-96ca-49bb-9ec3-926bee38fc89
ORCID for Harry L. Bryden: ORCID iD orcid.org/0000-0002-8216-6359

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Date deposited: 26 Feb 2020 17:30
Last modified: 18 Feb 2021 16:46

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Author: Harry L. Bryden ORCID iD
Author: William E. Johns
Author: Brian A. King
Author: Gerard Mccarthy
Author: Elaine L. Mcdonagh
Author: Ben I. Moat
Author: David A. Smeed

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