Variability of the net air-sea CO 2 flux inferred from shipboard and satellite measurements in the Southern Ocean south of Tasmania and New Zealand

• Published in: Journal of Geophysical Research
• Main Authors: Rangama, Yvan, Boutin, Jacqueline, Etcheto, Jacqueline, Merlivat, Liliane, Takahashi, Taro, Delille, Bruno, Frankignoulle, M., Bakker, Dorothee C. E.
• Other Authors: 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), Lamont-Doherty Earth Observatory (LDEO), Columbia University New York, Unité d'Océanographie Chimique, Interfacultary Center for Marine Research (MARE), Université de Liège-Université de Liège, School of Environmental Sciences Norwich, University of East Anglia Norwich (UEA)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2005
• 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; Southern Ocean; New Zealand
• Online Access: https://hal.science/hal-00124824; https://hal.science/hal-00124824/document; https://hal.science/hal-00124824/file/2004JC002619.pdf; https://doi.org/10.1029/2004JC002619

International audience We determine the distribution of oceanic CO 2 partial pressure (pCO 2 ) with respect to remotely sensed parameters (sea surface temperature (SST) and chlorophyll (Chl)) in order to gain an understanding of the small-scale (10-100 km) pCO 2 variability and to estimate the net air-sea CO 2 flux in the region (125°E-205°E; 45°S-60°S), which represents 22% of the Southern Ocean area between 45°S and 60°S. We split the study area into several biogeochemical provinces. In chlorophyll-poor regions, pCO 2 is negatively correlated with SST, indicating that pCO 2 is mostly controlled by mixing processes. For Chl > 0.37 mg m 3 , pCO 2 is negatively correlated with Chl, indicating that pCO 2 variability is mostly controlled by carbon fixation by biological activity. We deduce fields of pCO 2 and of air-sea CO 2 fluxes from satellite parameters using pCO 2 -SST, pCO 2 -chlorophyll relationships and air-sea gas exchange coefficient, K, from satellite wind speed. We estimate an oceanic CO 2 sink from December 1997 to December 1998 of À0.08 GtC yr -1 with an error of 0.03 GtC yr -1 . This sink is approximately 38% smaller than that computed from the Takahashi et al. (2002) climatological distribution of DpCO 2 for the 1995 year but with the same K (-0.13 GtC yr -1 ). When we correct ocean pCO 2 for the interannual variability between 1995 and 1998, the difference is even larger, and we cannot reconcile both estimates in February-March and from June to November. This strengthens the need of new in situ measurements for validating extrapolation methods and for improving knowledge of interannual pCO 2 variability.