Water mass transformation and its relationship with the overturning circulation in the eastern subpolar North Atlantic

Fu, Yao ORCID: https://orcid.org/0000-0003-2227-3694; Lozier, M. Susan; Majumder, Sudip ORCID: https://orcid.org/0000-0002-0431-2189; Petit, Tillys. 2024 Water mass transformation and its relationship with the overturning circulation in the eastern subpolar North Atlantic. Journal of Geophysical Research: Oceans, 129 (12). 10.1029/2024JC021222

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Text © 2024 The Author(s).This is an open access article under the terms of the Creative Commons Attribution‐Non Commercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes. JGR Oceans - 2024 - Fu - Water Mass Transformation and Its Relationship With the Overturning Circulation in the Eastern.pdf - Published Version Available under License Creative Commons Attribution Non-commercial 4.0. Download (2MB) | Preview

Abstract/Summary

A recent study using the first 21 months of the OSNAP time series revealed that the export of dense waters in the eastern subpolar North Atlantic―as part of the Atlantic Meridional Overturning Circulation (MOC)―can be almost wholly attributed to surface-forced water mass transformation (SFWMT) in the Irminger and Iceland basins, thus suggesting a minor role for other means of transformation, such as diapycnal mixing. To understand whether this result is valid over a period that exceeds the current observational record, we use four different ocean reanalysis products to investigate the relationship between surface buoyancy forcing and dense water production in this region. We also reexplore this relationship with the now available 6-year OSNAP time series. Our analysis finds that although surface transformation in the eastern subpolar gyre dominates the production of deep waters, mixing processes downstream of the Greenland Scotland Ridge are also responsible for the production of waters carried within the AMOC's lower limb both in the observations and reanalyses. Further analysis of the reanalyses shows that SFWMT partly explains MOC interannual variability, the remaining portion can be attributed to basin storage and mixing. Compared to the observations, the reanalyses exhibit stronger MOC variance but comparable SFWMT variance on interannual timescales.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	10.1029/2024JC021222
ISSN:	2169-9275
Additional Keywords:	AMOC, water mass transformation, OSNAP
Date made live:	16 Jan 2025 13:27 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/538751

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