The CoASTS-BiOMaP data set of hyperspectral absorption coefficients, complementary to the bio-optical data set accessible at https://doi.org/10.1594/PANGAEA.971945, were determined from laboratory analysis of discrete water samples collected at approximately 1 m depth during the Coastal Atmosphere & Sea Time Series (CoASTS) and the Bio-Optical mapping of Marine optical Properties (BiOMaP) measurement programs. The dataset, resulting from the collaboration between the Marine Optical Laboratory of the Joint Research Center (JRC) and a number of European national institutions, comprises absorption coefficients of pigmented and non-pigmented particles in the 400-750 nm interval, and those by colored dissolved organic matter in the 350-680 nm interval, provided with 3 nm spectral resolution at 2 nm increment. All coefficients were determined applying identical sampling, laboratory, processing and quality control methods, regardless of the measurement program or geographic areas. A few spectra of absorption coefficients for pigmented particles exhibit some unrealistic negative values beyond approximately 500 nm explained by limits of the measurement methodology in the presence of a low concentration of particles largely associated with sampling in oligotrophic waters. These spectra were not excluded from the data set expecting their application can be still relevant once the absorption coefficients are corrected for their background in the near-infrared. Overall, the data set comprises absorption spectra from 2549 stations. Of these, 634 stations refer to 125 CoASTS field campaigns performed from October 1998 up to March 2016 on-board the Acqua Alta Oceanographic Tower (AAOT) in the northern Adriatic Sea representing moderate optically complex waters with properties largely determined by phytoplankton, as well as diverse concentrations of suspended particulate matter (SPM) and of coloured dissolved organic matter (CDOM). The remaining 1915 stations are from 36 BiOMaP oceanographic campaigns performed between July 2000 and May 2022 in various European marine regions: the Baltic Sea with waters dominated by a high concentration of CDOM; the Adriatic Sea, Black Sea, North Sea (comprising the English Channel), Ligurian Sea, Iberian Shelf and the Greenland Sea, exhibiting a variety of optically complex waters determined by diverse concentrations of CDOM and SPM; the Eastern and Western Mediterranean oligotrophic and mesotrophic Seas.

(a) Station identifier Code Gccssii: G indicates the site or geographic region (V and W for the Acqua Alta Oceanographic Tower (AAOT) in the northern Adriatic Sea, A for Adriatic Sea, B for Baltic Sea, E for Eastern Mediterranean Sea, K for Black Sea, L for Ligurian Sea, N for North Sea, O for Western Mediterranean Sea, I for Iberian Shelf, P for Greenland Sea), while cc indicates the campaign number for the specific region, ss the station number and ii the cast number.