New insights into fCO 2 variability in the tropical eastern Pacific Ocean using SMOS SSS

• Main Authors: Walker Brown, C., Boutin, J., Merlivat, L.
• 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)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2015
• Subjects: Earth Science; [SDU]Sciences of the Universe [physics]; Pacific; Sea ice
• Online Access: https://hal.science/hal-04115497; https://doi.org/10.5194/bg-12-7315-201510.5194/bgd-12-4595-2015

International audience Complex oceanic circulation and air-sea interaction make the eastern tropical Pacific Ocean (ETPO) a highly variable source of CO 2 to the atmosphere. Although the scientific community have amassed 70 000 surface fugacities of carbon dioxide (fCO 2 ) data points within the ETPO region over the past 25 years, the spatial and temporal resolution of this data set is insufficient to fully quantify the seasonal to interannual variability of the region, a region where fCO 2 has been observed to fluctuate by > 300 μatm. Upwelling and rainfall events dominate the surface physical and chemical characteristics of the ETPO, with both yielding unique signatures in sea surface temperature and salinity. Thus, we explore the potential of using a statistical description of fCO 2 within sea-surface salinity-temperature space. These SSS/SST relationships are based on in situ surface ocean CO 2 atlas (SOCAT) data collected within the ETPO. This statistical description is then applied to high-resolution (0.25°) Soil Moisture and Ocean Salinity (SMOS) sea surface salinity (SSS) and Operational Sea Surface Temperature and Sea Ice Analysis (OSTIA) sea surface temperature (SST) in order to compute regional fCO 2 . As a result, we are able to resolve fCO 2 at sufficiently high resolution to elucidate the influence that various physical processes have on the fCO 2 of the surface ETPO. Normalised (to 2014) oceanic fCO 2 between July 2010 and June 2014 within the entire ETPO was 39 (±10.7) μatm supersaturated with respect to 2014 atmospheric partial pressures, and featured a CO 2 outgassing of 1.51 (±0.41) mmol m -2 d -1 . Values of fCO 2 within the ETPO were found to be broadly split between the Gulf of Panama region and the rest of the tropical eastern Pacific Ocean. The northwest, central and offshore regions were supersaturated, with wintertime wind-jet-driven upwelling found to constitute the first-order control on fCO 2 values. This contrasts with the southeastern/Gulf of Panama region, where heavy ...