Global surface ocean fCO2 from CSIR-ML6 (v2024)

The CSIR-ML6-v2024 is an update to the original CSIR-ML6 method by Gregor et al. (2019), extending the CO2 data product until 2023-12-15. The following changes have been made:

• SOCAT-v2024 is used;
• ERA5 reanalysis wind data and mean sea level pressure (MSLP) are used (instead of ERA-interim);
• The gas-exchange coefficient (kw) used, is appropriately scaled for the ERA5 wind product as recommended by Fay and Gregor et al. (2021);
• fCO2, the sea surface fugacity of CO2 is reported as per the Global Carbon Budget recommendation instead of pCO2, the sea surface partial pressure of CO2.

NETCDF FILE:

The dataset is stored in a single netCDF file and it mainly contains the following data variables:

• sfco2 = surface fugacity of CO2 for the ensemble average (in µatm). There
• fgco2 = air-sea CO2 fluxes (in mol m-2 yr-1).
• area = is the total surface ocean area per 1º by 1º grid cell (in m2) - doubles as mask for the data.
• sol: is the solubility of CO2 in seawater, in units mol m−3 𝜇atm−1, calculated using the Weiss (1974) parameterization with EN4 salinity and OISST temperatures.
• kw: is the gas transfer velocity, calculated for wind speed (ERA-5) scaled independently to a 14-C bomb flux estimate of 16.5 cm/hr using the quadratic formulation by Wanninkhof (1992).
• 𝑖𝑐𝑒: is the ice fraction, i.e. the open ocean fraction, to account for the seasonal ice cover in high latitudes.
• afco2: is the atmospheric fCO2 from NOAA's marine boundary layer product.

CITATION

Please cite the dataset as Djeutchouang et al. (2024), see the DOI: 10.6084/m9.figshare.26564140, as well as the original publication by Gregor et al. (2019), see the DOI: 10.5194/gmd-12-5113-2019.

HOST

CSIR, Southern Ocean Carbon – Climate Observatory (SOCCO)