Seasonality of the Meridional Overturning Circulation in the subpolar North Atlantic

Subpolar overturning in the North Atlantic Ocean shows substantial seasonality, with a maximum in late spring, a minimum in early winter, and a total range of about 9 Sv, according to observations from the OSNAP array between 2014 and 2020. Understanding the variability of the Atlantic Meridional Ov...

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Bibliographic Details
Published in:Communications Earth & Environment
Main Authors: Fu, Yao, Lozier, M. Susan, Biló, Tiago Carrilho, Bower, Amy S., Cunningham, Stuart A., Cyr, Frédéric, de Jong, M. Femke, deYoung, Brad, Drysdale, Lewis, Fraser, Neil, Fried, Nora, Furey, Heather H., Han, Guoqi, Handmann, Patricia, Holliday, N. Penny, Holte, James, Inall, Mark E., Johns, William E., Jones, Sam, Karstensen, Johannes, Li, Feili, Pacini, Astrid, Pickart, Robert S., Rayner, Darren, Straneo, Fiammetta, Yashayaev, Igor
Format: Article in Journal/Newspaper
Language:English
Published: Nature Research 2023
Subjects:
North Atlantic
Online Access:https://oceanrep.geomar.de/id/eprint/58782/
https://oceanrep.geomar.de/id/eprint/58782/1/s43247-023-00848-9.pdf
https://www.nature.com/articles/s43247-023-00848-9
https://doi.org/10.1038/s43247-023-00848-9
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Summary:Subpolar overturning in the North Atlantic Ocean shows substantial seasonality, with a maximum in late spring, a minimum in early winter, and a total range of about 9 Sv, according to observations from the OSNAP array between 2014 and 2020. Understanding the variability of the Atlantic Meridional Overturning Circulation is essential for better predictions of our changing climate. Here we present an updated time series (August 2014 to June 2020) from the Overturning in the Subpolar North Atlantic Program. The 6-year time series allows us to observe the seasonality of the subpolar overturning and meridional heat and freshwater transports. The overturning peaks in late spring and reaches a minimum in early winter, with a peak-to-trough range of 9.0 Sv. The overturning seasonal timing can be explained by winter transformation and the export of dense water, modulated by a seasonally varying Ekman transport. Furthermore, over 55% of the total meridional freshwater transport variability can be explained by its seasonality, largely owing to overturning dynamics. Our results provide the first observational analysis of seasonality in the subpolar North Atlantic overturning and highlight its important contribution to the total overturning variability observed to date.

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