Wind-driven and buoyancy-driven circulation in the subtropical North Atlantic Ocean
Wind-driven and buoyancy-driven circulation in the subtropical North Atlantic Ocean
Continuous observations of ocean circulation at 26°N in the subtropical Atlantic Ocean have been made since April 2004 to quantify the strength and variability in the Atlantic Meridional overturning circulation (AMOC), in which warm, upper waters flow northward and colder deep waters below 1100 m depth return southward. The principal components of the AMOC are northward western boundary current transport in the Gulf Stream and Antilles Current, northward surface Ekman transport and southward thermocline recirculation, all of which are generally considered to be part of the wind-driven circulation. Southward flowing deep waters below 1100 m depth are usually considered to represent the buoyancy-driven circulation. We argue that the Gulf Stream is partially wind-driven but also partially buoyancy-driven as it returns upper waters upwelled in the global ocean back to water mass formation regions in the northern Atlantic. Seasonal to interannual variations in the circulation at 26°N are principally wind-driven. Variability in the buoyancy-driven circulation occurred in a sharp reduction in 2009 in the southward flow of Lower North Atlantic Deep Water when its transport decreased by 30% from pre-2009 values. Over the 14-year observational period from 2004 to 2018, the AMOC declined by 2.4 Sv from 18.3 to 15.9 Sv.
Atlantic Meridional overturning circulation, Gulf Stream, Rapid observations, buoyancy-driven circulation, ocean circulation, wind-driven circulation
Bryden, Harry L.
7f823946-34e8-48a3-8bd4-a72d2d749184
8 December 2021
Bryden, Harry L.
7f823946-34e8-48a3-8bd4-a72d2d749184
Bryden, Harry L.
(2021)
Wind-driven and buoyancy-driven circulation in the subtropical North Atlantic Ocean.
Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences, 477 (2256).
(doi:10.1098/rspa.2021.0172).
Abstract
Continuous observations of ocean circulation at 26°N in the subtropical Atlantic Ocean have been made since April 2004 to quantify the strength and variability in the Atlantic Meridional overturning circulation (AMOC), in which warm, upper waters flow northward and colder deep waters below 1100 m depth return southward. The principal components of the AMOC are northward western boundary current transport in the Gulf Stream and Antilles Current, northward surface Ekman transport and southward thermocline recirculation, all of which are generally considered to be part of the wind-driven circulation. Southward flowing deep waters below 1100 m depth are usually considered to represent the buoyancy-driven circulation. We argue that the Gulf Stream is partially wind-driven but also partially buoyancy-driven as it returns upper waters upwelled in the global ocean back to water mass formation regions in the northern Atlantic. Seasonal to interannual variations in the circulation at 26°N are principally wind-driven. Variability in the buoyancy-driven circulation occurred in a sharp reduction in 2009 in the southward flow of Lower North Atlantic Deep Water when its transport decreased by 30% from pre-2009 values. Over the 14-year observational period from 2004 to 2018, the AMOC declined by 2.4 Sv from 18.3 to 15.9 Sv.
Text
rspa.2021.0172 (1)
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More information
Accepted/In Press date: 5 November 2021
e-pub ahead of print date: 8 December 2021
Published date: 8 December 2021
Keywords:
Atlantic Meridional overturning circulation, Gulf Stream, Rapid observations, buoyancy-driven circulation, ocean circulation, wind-driven circulation
Identifiers
Local EPrints ID: 455125
URI: http://eprints.soton.ac.uk/id/eprint/455125
ISSN: 1364-5021
PURE UUID: 09589a30-4e0a-424c-bbe5-5d6e1011ca2c
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Date deposited: 10 Mar 2022 17:32
Last modified: 17 Mar 2024 02:43
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