Transports and pathways of the tropical AMOC return flow from Argo data and shipboard velocity measurements

DOI

The upper-ocean circulation of the tropical Atlantic is a complex superposition of thermohaline and wind-driven flow components. The resulting zonally- and vertically-integrated upper-ocean meridional flow is referred to as the upper branch of the Atlantic Meridional Overturning Circulation (AMOC) - a major component and potential tipping element of the global climate system. We investigate the tropical part of the northward AMOC branch, i.e. the return flow covering the upper 1,200 m, based on Argo data and repeated shipboard velocity measurements. The western boundary mean circulation at 11°S is realistically reproduced from high-resolution Argo data showing a remarkably good representation of the vertical structure of meridional velocity and the volume transport of water mass layers when compared to results from direct velocity measurements along a repeated ship section. Thus, we extend the analysis to the inner tropical Atlantic. Within the AMOC return flow, a diapycnal upwelling of central water into the thermocline layer of ~2 Sv is derived between 11°S and 10°N which is about half the magnitude of previous estimates, likely due to improved horizontal resolution. The mean strength of the AMOC return flow is ~16 Sv across 11°S and 10°N. At 11°S, northward transport is concentrated at the western boundary where the AMOC return flow enters the tropics at all vertical layers above 1,200 m. At 10°N, northward transport is observed both at the western boundary and in the interior predominantly in the surface and intermediate layer indicating recirculation and transformation of thermocline and central water within the tropics.

Identifier
DOI https://doi.org/10.1594/PANGAEA.937809
Related Identifier IsSupplementTo https://doi.org/10.1029/2021JC018115
Metadata Access https://ws.pangaea.de/oai/provider?verb=GetRecord&metadataPrefix=datacite4&identifier=oai:pangaea.de:doi:10.1594/PANGAEA.937809
Provenance
Creator Tuchen, Franz Philip (Ed.) ORCID logo; Brandt, Peter (Ed.) (ORCID: 0000-0002-9235-955X); Lübbecke, Joke (Ed.) ORCID logo; Hummels, Rebecca (Ed.) ORCID logo
Publisher PANGAEA
Publication Year 2021
Funding Reference Horizon 2020 https://doi.org/10.13039/501100007601 Crossref Funder ID 817578 https://doi.org/10.3030/817578 Tropical and South Atlantic climate-based marine ecosystem predictions for sustainable management
Rights Creative Commons Attribution 4.0 International; https://creativecommons.org/licenses/by/4.0/
OpenAccess true
Representation
Resource Type Editorial Publication of Datasets; Collection
Size 46 datasets
Discipline Geosciences; Natural Sciences; Oceanography/Marine Science; Physical Oceanography
Spatial Coverage (-70.909W, -53.145S, 18.435E, 53.564N)
Temporal Coverage Begin 1990-10-06T16:05:00Z
Temporal Coverage End 2019-11-19T00:00:00Z