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 μμmol kg−1, are more important than the year-to-year variability that is less than 50 μμmol 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.
Highlights
dissolved inorganic carbon (DIC) distribution has been examined in the Eastern Tropical Atlantic (ETA) (12◦ W–12◦ E, 12◦ S–12◦ N) as well trations as theAccording factors controlling its distribution
The fugacity of CO2 (fCO2) monitoring relatively fresh and warm waters are associated with lower DIC concentrations compared is still sparse in the tropical Atlantic to conclude
2010 and 2012 affected fCO2 and suggest an important role of sea surface temperature (SST) anomalies whereas in regression between DIC and SST, sea surface salinity (SSS) and year has been determined with SSS as the main the ETA, DIC is mainly driven by SSS variations
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Tropical regions are strong sources of CO2 to the atmosphere due to the equatorial upwellings, bringing CO2 -rich waters to the surface, and to high sea surface temperatures. The Pacific Ocean is the most studied as El Niño events develop there and they are the dominant process governing the interannual variability of the air–. Sea CO2 flux (e.g., [1]). The Atlantic Ocean has been less studied with relatively fewer observations and modelling analyses [2]. The Western Tropical Atlantic (WTA) and the Eastern Tropical Atlantic (ETA) receive the discharge of the two largest rivers of the world with the Amazon, near the equator in the west, and the Congo near 6◦ S in the east
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