4DMED-2D Phytoplankton Functional Types (PFT) and Diffuse Attenuation Coefficients (Kd) (L3, 8 km, monthly, 2019–2021)

This dataset contains monthly Level-3 (L3) gridded maps (8 km resolution) of phytoplankton functional types (PFTs) and diffuse attenuation coefficients (Kd) for the period January 2019 to December 2021. PFT products: Chlorophyll-a concentrations of diatoms, haptophytes, dinoflagellates, green algae, and prokaryotes [mg m⁻³], retrieved using the method described in Xi et al. (2021). Input satellite products were obtained from the Copernicus Marine Service. Kd products: Diffuse attenuation coefficients in the UV and blue spectral ranges [m⁻¹], retrieved from Sentinel-5P TROPOMI using DOAS fitting of the vibrational Raman scattering (VRS) signal and radiative transfer–based LUTs, following Oelker et al. (2022). The LUTs and parameterizations were subsequently updated, and the current implementation is described in the S5P-PAL Product User Manual (PUM) (S5P-PAL data portal). For the ESA 4DMedSea project, these products were aggregated into temporal and spatial scales suitable for clustering the Mediterranean Sea into ecological regions. Validation was performed against BGC-Argo profiles and additional in-situ datasets. Data files are provided in NetCDF format, bundled into two compressed archives (PFT.zip and KD.zip). Each archive contains monthly fields for the full time period. These datasets support studies of phytoplankton diversity, dissolved organic matter (DOM), and underwater light availability in the surface ocean, particularly in the Mediterranean Sea.