Design of an observational strategy for quantifying the Southern Ocean uptake of CO 2

• Published in: Global Biogeochemical Cycles
• Main Authors: Lenton, Andrew, Matear, Richard J., Tilbrook, Bronte
• 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), Institute of Antarctic and Southern Ocean Studies (IASOS), University of Tasmania Hobart, Australia (UTAS), Antarctic Climate and Ecosystems Cooperative Research Centre (ACE-CRC)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2006
• Subjects: Biogeosciences: Climate dynamics (1620); [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-00770730; https://hal.science/hal-00770730/document; https://hal.science/hal-00770730/file/2005GB002620.pdf; https://doi.org/10.1029/2005GB002620

International audience A sampling strategy to estimate the annual mean CO 2 uptake by the Southern Ocean was developed by applying two-dimensional Fourier transforms and signal-to-noise ratios to the simulated air-sea CO 2 fluxes and ΔpCO 2 from an ocean biogeochemical model driven with NCEP-R1. Observations of pCO 2 were used to validate the statistical properties of the model and to estimate the mesoscale variability not captured by the model resolution. Sampling regularly every 3 months, at every 30° in longitude and 3° in latitude is sufficient to determine the net Southern Ocean CO 2 uptake. We applied this sampling strategy to the simulated air-sea fluxes to estimate a net annual mean CO 2 uptake of 0.6 +/- 0.1 PgC/yr (1990-1999). This uncertainty in the estimate was dominated by the simulated interannual variability, and not by errors in the sampling or unresolved mesoscale variability. Therefore sampling at higher resolutions in space and time would not reduce the uncertainty in the Southern Ocean annual mean uptake any further. These results show that a doubling of the current Southern Ocean sampling (in longitude) would be required to constrain the net annual mean air-sea CO 2 fluxes to within the natural variability of the system.