Publication
Evolution of the Oceanic 13C Suess Effect in the Southeastern Indian Ocean Between 1994 and 2018
Publisher:
American Geophysical Union (AGU)
Date:
04-2021
DOI:
10.1029/2020GC009402
Abstract: The decrease in δ 13 C of dissolved inorganic carbon (δ 13 C DIC ) owing to uptake of anthropogenic CO 2 (the oceanic 13 C Suess effect) in the Southeastern Indian Ocean over the last decade was calculated using an extended multiparameter linear regression technique. S les collected on the CROCCA‐2S (Coring to Reconstruct Ocean Circulation and Carbon Dioxide Across 2 Seas) cruise in November–December 2018 were compared to s les from the CLIVAR (Climate and Ocean: Variability, Predictability, and Change) and OISO (Océan Indien Service d'Observation) programs from 2007 to 2009. Surface ocean δ 13 C DIC decreased by an average of −0.53 ± 0.04‰ across this period, at an average rate of −0.053 ± 0.004‰ per year. This rate of δ 13 C DIC change is an increase from −0.021 ± 0.024‰ per year between 1994 and 2008. We find that the interior water mass most impacted by the oceanic 13 C Suess effect between 2008 and 2018 was Subantarctic Mode Water (SAMW), within which δ 13 C DIC decreased by −0.044 ± 0.002‰ per year. Using previously published relationships between the oceanic 13 C Suess effect and anthropogenic carbon, we estimate the annual storage of anthropogenic carbon within SAMW in the southeastern Indian Ocean has increased from ∼2.0 ± 0.2 μmol/kg per year between 1994 and 2008 to 5.5 ± 0.6 μmol/kg per year between 2008 and 2018.