Summer and winter distribution of δ 13 C DIC in surface waters of the South Indian Ocean [20°S-60°S]

• Published in: Tellus B: Chemical and Physical Meteorology
• Main Authors: Racapé, Virginie, Lo Monaco, Claire, Metzl, Nicolas, Pierre, Catherine
• Other Authors: Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales Toulouse (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales Toulouse (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2010
• Subjects: [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph]; [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph]; [SDE.MCG]Environmental Sciences/Global Changes; Antarctic; Austral; Kerguelen; Indian; Antarc*
• Online Access: https://hal.archives-ouvertes.fr/hal-00759242; https://doi.org/10.1111/J.1600-0889.2010.00504.X

International audience This paper describes for the first time the summer and winter distributions of sea surface δ 13 C DIC in the Southern Indian Ocean (20°S-60°S). For this we used δ 13 C DIC measurements from 10 cruises conducted between 1998 and 2005. For summer and winter, the highest δ 13 C DIC values (>2‰) are observed in sub-Antarctic waters (40°S-50°S) and attributed mainly to biological activity, enhanced in the vicinity of Crozet and Kerguelen Archipelagoes. The lowest δ 13 C DIC values are found in subtropical waters (25°S-35°S), with a minimum (<1‰) in the Agulhas Current region and in the Mozambique channel. On the seasonal scale, δ 13 C DIC is higher during summer than during winter in all regions. The largest seasonal amplitude of variation (~0.3‰), observed in the region 35°S-40°S, is attributed to biological activity during summer and to deep vertical mixing during winter. In subtropical oligotrophic waters, the mean seasonal amplitude of variation (~0.15‰) is mainly explained by air-sea CO 2 fluxes. On the interannual scale, we also identified a large negative anomaly of δ 13 C DIC in the subtropical waters during austral summer 2002, associated to an anomalous ocean CO 2 sink due to cold conditions during this period.