Trends and drivers of CO2 parameters, from 2006 to 2021, at a time-series station in the Eastern Tropical Atlantic

Trends and drivers of CO2 parameters, from 2006 to 2021, at a time-series station in the Eastern Tropical Atlantic Lefèvre Nathalie auteur aut IRD Veleda D. auteur aut IRD Beaumont L. auteur aut IRD text journalArticle eng text/pdf born digital access The seawater fugacity of CO2 (fCO(2)) has been monitored hourly at an instrumented mooring at 6 degrees S, 10 degrees W since 2006. The mooring is located in the South Equatorial Current and is affected by the equatorial Atlantic cold tongue. This site is characterized by large seasonal sea surface temperature variations (>4 degrees C). The fCO(2) is measured by a spectrophotometric sensor deployed at about 1.5 meters deep. Measurements of seawater fCO(2), sea surface temperature (SST) and sea surface salinity (SSS) are used to calculate total dissolved inorganic carbon (TCO2) and pH. Total alkalinity (TA) is calculated using an empirical relationship with SSS determined for this region. Satellite chlorophyll-a concentrations at 6 degrees S, 10 degrees W are low (<0.2 mg m(-3)) but some peaks over 0.8 mg m(-3) are sometimes detected in August. Nevertheless, the site is a permanent source of CO2 to the atmosphere, averaging 4.7 +/- 2.4 mmol m(-2)d(-1) over 2006-2021. Despite the weakening of the wind, the CO2 flux increases significantly by 0.20 +/- 0.05 mmol m(-2)d(-1) yr(-1). This suggests that the source of CO2 is increasing in this region. This is explained by seawater fCO(2) increasing faster than the atmospheric increase during 2006-2021. Most of the seawater fCO(2) increase is driven by the increase of TCO2, followed by SST. The fCO(2) increase leads to a pH decrease of -0.0030 +/- 0.0004 yr(-1). The SST anomalies (SSTA) at 6 degrees S, 10 degrees W are correlated to the Tropical Southern Atlantic (TSA) index and to the Atlantic 3 region (ATL3) index with a correlation coefficient higher than 0.75. The strong positive phase of both ATL3 and TSA, observed towards the end of the time-series, is likely contributing to the strong increase of seawater fCO(2.) specialized acidification fugacity of CO2 carbon cycle tropical Southern Atlantic index PIRATA mooring ATLANTIQUE ZONE TROPICALE 032 Frontiers in Marine Science 11 1299071 [14 p.] 2024 https://www.documentation.ird.fr/hor/fdi:010089611 10.3389/fmars.2024.1299071 [F B010089611] https://www.documentation.ird.fr/hor/fdi:010089611 https://www.documentation.ird.fr/intranet/publi/2024-04/010089611.pdf Accès réservé (Intranet de l'IRD) IRD - Base Horizon / Pleins textes 2024-04-05 2025-11-06 fdi:010089611 fre