Global surface ocean fCO2 from CSIR-ML6 (v2025)

The CSIR-ML6-v2025 revises the original CSIR-ML6 method by Gregor et al. (2019), extending the monthly CO2 data product through December 15, 2024. The following modifications have been implemented:SOCAT-v2025 is now used.ERA5 reanalysis wind data and mean sea level pressure (MSLP) replace ERA-interim data.kw, the gas-exchange coefficient, has been scaled appropriately for the ERA5 wind product, following the recommendations of Fay and Gregor et al. (2021)fCO2, the sea surface fugacity of CO2, is reported according to the Global Carbon Budget guidelines, replacing pCO2, the sea surface partial pressure of CO2.NETCDF FILE:The dataset is stored in a single netCDF file containing the following main data variables:sfco2: surface fugacity of CO2 for the ensemble average (in µatm).fgco2: air-sea CO2 fluxes (in mol m-2 yr-1).area: the total surface ocean area per 1º by 1º grid cell (in m2), serving as a mask for the data.alpha: the solubility of CO2 in seawater, in mol m⁻³ µatm⁻¹, calculated using Weiss’s (1974) parameterization with EN4 salinity and OISST temperatures.kw: the gas transfer velocity(kw), appropriately scaled, for ERA-5 wind product, as recommended by Fay and Gregor et al. (2021).ice: the ice fraction, indicating the open ocean fraction, to account for seasonal ice cover in high latitudes.fco2atm: atmospheric fCO2 from NOAA's marine boundary layer product.PleasCITATION:Please cite the dataset as Djeutchouang et al. (2025), reference DOI: 10.6084/m9.figshare.26564140, and the original publication by Gregor et al. (2019), reference DOI: 10.5194/gmd-12-5113-2019.HOST:CSIR, Southern Ocean Carbon – Climate Observatory (SOCCO)