In situ and satellite based estimates of marine productivity: constraints on the seasonal cycle of the Southern Ocean surface pCO 2

• Main Authors: Merlivat, Liliane, Boutin, Jacqueline, Antoine, David
• Other Authors: Échanges dans la couche de surface : des pôles aux tropiques (SURF), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), 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-PSL), 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)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), 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), Laboratoire d'océanographie de Villefranche (LOV), Observatoire océanologique de Villefranche-sur-mer (OOVM), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)
• Format: Conference Object
• Language: English
• Published: HAL CCSD 2013
• 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]; Southern Ocean
• Online Access: https://hal.science/hal-00873744

International audience We estimate in situ biological carbon production rates from high frequency measurements along the trajectories of 6 CARIOCA drifters in the Atlantic and Indian sector of the Southern Ocean during 2006-2009 spring-summer periods. Net Community production (NCP) integrated over the mixed layer is derived from the daily change of the dissolved inorganic carbon (DIC) combined with mixed layer depths estimated from Argo profiles. Daily values of NCP range from 30 to 140 mmol C m -2 d -1 . A satellite based ocean color model is used to compute depth integrated marine net primary production (NPP) for the same periods along the trajectories of the buoys. As already mentioned by other authors, the SEAWIFS chlorophyll are underestimated by a factor ≈ 2-3 in the Southern Ocean. Taking this into account, the export ratio NCP/NPP is included between 0.2 and 0.9 and decreases with increasing sea surface temperature. Monthly satellite based NPP are computed over the 38°S-55°S, 60°W-60°E area of the Southern Ocean. A seasonal budget of DIC and pCO 2 in the mixed layer is assessed. We quantitatively separate all the physical and biological processes that control their monthly changes. A good agreement is found with pCO 2 climatology of Takahashi (2009). On an annual timescale, mean NCP is ≈ 4-5 times greater than mean CO 2 invasion, being respectively equal to -4.9 and 1.1 mol C m -2 yr -1 . Attention is drawn on key parameters that control the seasonal distribution of surface pCO 2 and air-sea CO 2 uptake that will have to be carefully monitored or modeled under changing environmental conditions.