Subpolar North Atlantic Overturning and Gyre-Scale Circulation in the Summers of 2014 and 2016

Holliday, N. P., Bacon, S., Cunningham, S. A., Gary, S. F., Karstensen, Johannes, King, B. A., Li, F. and Mcdonagh, E. L. (2018) Subpolar North Atlantic Overturning and Gyre-Scale Circulation in the Summers of 2014 and 2016 Journal of Geophysical Research: Oceans, 123 (7). pp. 4538-4559. DOI 10.1029/2018JC013841.

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The Atlantic Meridional Overturning Circulation (AMOC) is a key component of the global climate system through its transport of heat and freshwater. The subpolar North Atlantic (SPNA) is a region where the AMOC is actively developed and shaped though mixing and water mass transformation and where large amounts of heat are released to the atmosphere. Two hydrographic transbasin sections in the summers of 2014 and 2016 provide highly spatially resolved views of the SPNA velocity and property fields on a line from Canada to Greenland to Scotland. Estimates of the AMOC, isopycnal (gyre-scale) transport, and heat and freshwater transport are derived from the observations. The overturning circulation, the maximum in northward transport integrated from the surface to seafloor and computed in density space, has a high range, with 20.6 ± 4.7 Sv in June-July 2014 and 10.6 ± 4.3 Sv in May-August 2016. In contrast, the isopycnal (gyre-scale) circulation was lowest in summer 2014: 41.3 ± 8.2 Sv compared to 58.6 ± 7.4 Sv in 2016. The heat transport (0.39 ± 0.08 PW in summer 2014, positive is northward) was highest for the section with the highest AMOC, and the freshwater transport was largest in summer 2016 when the isopycnal circulation was high (-0.25 ± 0.08 Sv). Up to 65% of the heat and freshwater transport was carried by the isopycnal circulation, with isopycnal property transport highest in the western Labrador Sea and the eastern basins (Iceland Basin to Scotland).

Document Type: Article
Keywords: Atlantic Meridional Overturning Circulation; Freshwater transport; Heat transport; Isopycnal circulation; Subpolar North Atlantic
Research affiliation: NOC
OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-PO Physical Oceanography
Refereed: Yes
DOI etc.: 10.1029/2018JC013841
ISSN: 2169-9275
Projects: NACLIM, RACE II, AtlantOS, Blue-Action
Date Deposited: 13 Aug 2018 09:45
Last Modified: 06 Sep 2018 08:44

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