A POSEIDON FerryBox contribution to the international Surface Ocean CO₂ Atlas: a second small step from POSEIDON towards filling the Eastern Mediterranean CO₂ data gap
The POSEIDON system, through its FerryBox operating on the Heraklion–Piraeus ferry route—currently the only FerryBox system in the Eastern Mediterranean—has contributed pCO₂ data to the Surface Ocean CO₂ Atlas (SOCAT). Although the dataset covers only one month (August 2023), with daily transect data, its submission to SOCAT is significant given the acute scarcity of surface ocean CO₂ observations in this region. The Eastern Mediterranean is characterised by a paucity of marine CO₂ data, which prevents the area from being conclusively classified as either a net source or sink of CO₂. Together with the multi-year pCO₂ time series from the POSEIDON fixed platform at the Heraklion Coastal Buoy (HCB)—the first marine CO₂ time series obtained in the Eastern Mediterranean (Frangoulis et al., 2024)—the FerryBox CO₂ dataset represents one of the very few Eastern Mediterranean contributions to SOCAT, and the only one from a FerryBox platform. Despite its limited temporal extent and the subsequent non-operation of the FerryBox, this contribution remains valuable because, together with the earlier HCB observations, they represent the only two Eastern Mediterranean datasets in SOCAT from 2020 to the present.
SOCAT data spatial coverage from the period 2020 to 2025 obtained using the SOCAT Data Viewer (Live Access Server) at global scale and with inset showing the Eastern Mediterranean Sea. The black box show the location of POSEIDON Ferrybox and HCB. Data sourced from Bakker, D. C. E., et al. (2026).
Bakker, D. C. E., et al. (2026). Surface Ocean CO2 Atlas Database Version 2026 (SOCATv2026) (NCEI Accession 0315110). NOAA National Centers for Environmental Information. Dataset. https://doi.org/10.25921/8dba-fr90
Frangoulis, C. et al. (2024). A carbonate system time series in the Eastern Mediterranean Sea. Two years of high-frequency in-situ observations and remote sensing. Frontiers in Marine Science, 11, 1348161. https://doi.org/10.3389/fmars.2024.1348161
