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The North Atlantic Basin is a major sink for atmospheric carbon dioxide (CO₂) due in part to the extensive plankton blooms which form there supported by nutrients supplied by the three-dimensional ocean circulation. Hence, changes in ocean circulation and/or stratification may influence primary production and biological carbon export. In this study, we assessed this possibility by evaluating inorganic nutrient budgets for 2004 and 2010 in the North Atlantic, based on observations from the transatlantic A05-24.5°N and the
Greenland-Portugal OVIDE hydrographic sections, to which we applied a box inverse model to solve the circulation and estimate the across-section nutrient transports.
• The overturning circulation lower limb drives a net southward transport of oxygen and nutrients from the North to the South Atlantic
• Anomalous circulation in 2010 enhanced nutrient convergence by the overturning upper limb, boosting North Atlantic biological CO₂ uptake
• We observed a deep silicate divergence in the North Atlantic in 2004 and 2010 compatible with a transient response to reduced overturning
Citation: Carracedo, L. I., Mercier, H., McDonagh, E., Rosón, G., Sanders, R., Moore, C. M., et al. (2021). Counteracting contributions of the upper and lower meridional overturning limbs to the North Atlantic nutrient budgets: Enhanced imbalance in 2010. Global Biogeochemical Cycles, 35, e2020GB006898. https://doi. org/10.1029/2020GB006898
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2 IPCC, 2019: IPCC Special Report on the Ocean and Cryosphere in a Changing Climate [H.-O. Pörtner, D.C. Roberts, V. Masson-Delmotte, P. Zhai, M. Tignor, E. Poloczanska, K. Mintenbeck, A. Alegría, M. Nicolai, A. Okem, J. Petzold, B. Rama, N.M. Weyer (eds.)]. In press;
3 Baringer, M. O. & Larsen, J. C. Sixteen years of Florida Current Transport at 27° N. Geophys. Res. Lett. 28, 3179–3182 (2001);
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15:00 – 15.10 Welcome and overview Seminar Session 1.
15.10 – 15:25 AMOC across the OVIDE section. H. Mercier (LOPS, CNRS, France)
15:25 – 15:40 AMOC across RAPID section. E. Frajka-Williams (NOC, UK)
15:40 – 15:55 AMOC mechanisms. S. Lozier (Georgia Tech, Earth and Atmospheric Sciences, USA)
15:55 – 16:10 Latitudinal shift of the AMOC source regions. C. Lique (LOPS, Ifremer, France)
16:10 – 16:25 Mechanisms of ocean heat content variability. D. Desbruyères (LOPS, Ifremer, France)
16:25 – 16:40 Q&A. Closing up Science Seminar Session 1.
16:40 – 16:45 Overview Seminar Session 2.
16:45 – 17:00 Cant and excess ocean heat content in the Subtropical NA Ocean. M.J. Messias (Uni of Exeter, UK)
17:00 – 17:15 Cant in the subpolar gyre. F. F. Pérez (IIM-CSIC, Spain)
17:15 – 17:30 Cant transport across RAPID. P. Brown (NOC, UK)
17:30 – 17:45 MOC regulation of nutrient inventories in the North Atlantic. L. Carracedo (LOPS, Ifremer, France)
17:45 – 18:00 Q&A. Closing up Science Seminar Session 2.
14:30 – 14:40 Welcome and overview Seminar Session 3.
14:40 – 14:55 Florida Current variability. D. Volkov (AOML, NOAA, USA)
14:55 – 15:10 Likely weakening of the Florida Current during the past century. C. Piecuch (WHOI, USA)
15:10 – 15:25 Freshwater/heat transport across the Florida Strait. E. McDonagh (NORCE, Norway)
15:30 – 15:45 DIC transport across the Florida Strait. N. Bates (BIOS, Bermuda)
15:45 – 16:00 DIC transport and coastal acidification off the east coast of Florida. Y. Xu (AOML, NOAA, USA)
16:00 – 16:15 Surface OA in the Northern Caribbean Sea, including the FC. R. Wanninkhof (AOML, NOAA, USA)
16:15 – 16:30 Ocean carbon uptake in the Gulf Stream and STMW region. J. Palter (Uni of Rhode Island, USA)
16:35 – 16:50 The North Atlantic nutrient stream. R. Williams (Uni of Liverpool, UK)
16:50 – 17:05 N₂ fixation in the Gulf Stream. M. Benavides (MIO, France)
17:05 – 17:20 Diapycnal nutrient fluxes to the euphotic zone in the Florida Straits. J.Z. Zhang (AOML, NOAA, USA)
17:20 – 17:35 Nutrient variability across Florida Straits. L. Carracedo (LOPS, Ifremer, France)
17:35 – 17:50 Pursuing new measures of change in the Florida Straits, L. Beal & H. Close (RSMAS, Uni of Miami, USA)
17:50 – 18:00 Q&A. Closing up Science Seminar Session.