Ocean Circulation Drives the Variability of the Carbon System in the Eastern Tropical Atlantic

Type Article
Date 2021
Language English
Author(s) Lefèvre Nathalie1, Mejia Carlos1, Khvorostyanov Dmitry1, Beaumont Laurence2, Koffi Urbain3
Affiliation(s) 1 : Institut de Recherche Pour le Développement, Laboratoire d’Océanographie et du Climat Expérimentations et Approches Numériques (LOCEAN)/Sorbonne Université/Centre National de la Recherche Scientifique/Muséum National d’Histoire Naturel, 4 Place Jussieu, 75005 Paris, France
2 : Division Technique de l’Institut des Sciences de l’Univers, 1 Place Aristide Briand, 92195 Meudon, France
3 : Laboratoire des Sciences Physiques, Fondamentales et Appliquées de l’École Normale Supérieure, Abidjan 08 BP 10, Cote D’Ivoire
Source Oceans (2673-1924) (MDPI), 2021 , Vol. 2 , N. 1 , P. 126-148
DOI 10.3390/oceans2010008
Note This article belongs to the Special Issue Current Advances and Challenges in Ocean Science—Feature Papers for the Founding of Oceans
Keyword(s) carbon cycle, tropical Atlantic, dissolved inorganic carbon, alkalinity
Abstract

The carbon system in the eastern tropical Atlantic remains poorly known. The variability and drivers of the carbon system are assessed using surface dissolved inorganic carbon (DIC), alkalinity (TA) and fugacity of CO2 (fCO2) measured in the 12° N–12° S, 12° W–12° E region from 2005 to 2019. A relationship linking DIC to temperature, salinity and year has been determined, with salinity being the strongest predictor. The seasonal variations of DIC, ranging from 80 to 120 mol kg−1, are more important than the year-to-year variability that is less than 50 mol kg−1 over the 2010–2019 period. DIC and TA concentrations are lower in the northern part of the basin where surface waters are fresher and warmer. Carbon supply dominates over biological carbon uptake during the productive upwelling period from July to September. The lowest DIC and TA are located in the Congo plume. The influence of the Congo is still observed at the mooring at 6° S, 8° E as shown by large salinity and chlorophyll variations. Nevertheless, this site is a source of CO2 emissions into the atmosphere.

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