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Title: Pending recovery in the strength of the meridional overturning circulation at 26° N
Abstract. The strength of the Atlantic meridional overturning circulation(AMOC) at 26∘ N has now been continuously measured by the RAPIDarray over the period April 2004–September 2018. This record provides uniqueinsight into the variability of the large-scale ocean circulation,previously only measured by sporadic snapshots of basin-wide transport fromhydrographic sections. The continuous measurements have unveiled strikingvariability on timescales of days to a decade, driven largely bywind forcing, contrasting with previous expectations about a slowly varyingbuoyancy-forced large-scale ocean circulation. However, these measurementswere primarily observed during a warm state of the Atlantic multidecadalvariability (AMV) which has been steadily declining since a peak in2008–2010. In 2013–2015, a period of strong buoyancy forcing by theatmosphere drove intense water-mass transformation in the subpolar NorthAtlantic and provides a unique opportunity to investigate the response ofthe large-scale ocean circulation to buoyancy forcing. Modelling studiessuggest that the AMOC in the subtropics responds to such events with anincrease in overturning transport, after a lag of 3–9 years. At45∘ N, observations suggest that the AMOC may already beincreasing. Examining 26∘ N, we find that the AMOC is no longerweakening, though the recent transport is not above the long-term mean.Extending the record backwards in time at 26∘ N with oceanreanalysis from GloSea5, the transport fluctuations at 26∘ N areconsistent with a 0- to 2-year lag from those at 45∘ N, albeit withlower magnitude. Given the short span of time and anticipated delays in thesignal from the subpolar to subtropical gyres, it is not yet possible todetermine whether the subtropical AMOC strength is recovering nor how theAMOC at 26∘ N responds to intense buoyancy forcing.  more » « less
Award ID(s):
1332978 1926008
Author(s) / Creator(s):
; ; ; ; ; ; ; ; ; ; ;
Date Published:
Journal Name:
Ocean Science
Page Range / eLocation ID:
863 to 874
Medium: X
Sponsoring Org:
National Science Foundation
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