|Published in||Science advances, v. 6(32):eaba7573|
Kersalé, M., Meinen, Perez, C. S., Le Hénaff, D. Valla, R. C., Lamont, M., T.,  Sato, O. T., Dong, S., Terre, T., van Caspel, M., Chidichimo, M. P., van den Berg, M., Speich, S., Piola, A. R., Campos, E. J. D., Ansorge, I., Volkov, D. L., Lumpkin, R., Garzoli, S. L. Highly variable upper and abyssal overturning cells in the South Atlantic.
The U.S. PIES observations and the participation of C.S.M., R.C.P., and S.D. were supported via the NOAA Climate Program Office-Ocean Observing and Monitoring Division (FundRef no. 100007298) under the Southwest Atlantic Meridional Overturning Circulation (&ldquoSAM&rdquo) project. M.L.H. and M.K. acknowledge additional support from NASA (grant 80NSSC18K0773). D.L.V., M.K., M.L.H., and S.L.G. were supported in part under the auspices of the Cooperative Institute for Marine and Atmospheric Studies (CIMAS), a Cooperative Institute of the University of Miami and NOAA (cooperative agreement NA10OAR4320143), and/or under a grant from the NOAA Climate Variability Program (GC16-212). C.S.M., D.L.V., M.K., M.L.H., R.L., R.C.P., S.D., and S.L.G. also acknowledge additional support from the NOAA Atlantic Oceanographic and Meteorological Laboratory. S.S. and T.T. acknowledge support from the 11-ANR-56-004 SAMOC research project. S.S. also received support from the European Union Horizon 2020 research and innovation program under grant agreement 633211 (AtlantOS). E.J.D.C., M.v.C. and O.T.S. acknowledge the São Paulo State Research Foundation (FAPESP, grants 2011/50552-4, 2017/09659-6, 2018/09823-3, and 2019/07833-4), the Brazilian Navy (DHN and SeCIRM), and the University of São Paulo (Oceanographic Institute) for support through the SAMOC-Br project. E.J.D.C. also acknowledges CNPq for a Research Fellowship (grant 302018/2014-0). I.A., M.v.d.B., and T.L. acknowledge support from the DST-NRF-SANAP programme and the South African DEA. The Argentine cruises were supported by Servicio de Hidrografía Naval and CONICET. Additional support for A.R.P., D.V., E.J.D.C., and M.P.C. was provided by the Inter-American Institute for Global Change Research grant CRN3070 (U.S. NSF grant GEO-1128040).
The Meridional Overturning Circulation (MOC) is a primary mechanism driving oceanic heat redistribution on Earth, thereby affecting Earth&rsquos climate and weather. However, the full-depth structure and variability of the MOC are still poorly understood, particularly in the South Atlantic. This study presents unique multiyear records of the oceanic volume transport of both the upper (<~3100 meters) and abyssal (>~3100 meters) overturning cells based on daily moored measurements in the South Atlantic at 34.5°S. The vertical structure of the time-mean flows is consistent with the limited historical observations. Both the upper and abyssal cells exhibit a high degree of variability relative to the temporal means at time scales, ranging from a few days to a few weeks. Observed variations in the abyssal flow appear to be largely independent of the flow in the overlying upper cell. No meaningful trends are detected in either cell.