NECCTON D4.2 Assessment of L2 PRISMA production chain, outputs and transferability

Spaceborne imaging spectrometry provides measurements across numerous discrete narrow bands, forming a contiguous spectrum that enables the retrieval of key biogeophysical parameters in aquatic ecosystems, such as the characterization of phytoplankton, dissolved and suspended matter and other optically active biological constituents. One of the objectives of NECCTON is to provide Copernicus Marine Service (CMEMS) with new capability in fusing numerical model simulations and novel satellite observations, including new hyperspectral observations from the PRISMA satellite mission. Multiple biogeochemical models will be upgraded by adding bio-optical modules describing the distribution of in-water irradiance along the water column and the interaction of optically active substances with the spectral light field. The integration of hyperspectral imagery and biogeochemical models by means of augmented skill-performance metrics and novel assimilation techniques is a challenging application for improving model parameters and enhancing the description of plankton and optically active properties. A prerequisite for model validation and a successful data assimilation is an accurate estimation of uncertainties in the satellite observations. To this end, we explored the potential and limitations of PRISMA hyperspectral mission to provide water reflectance products in coastal and marine sites, where PRISMA data are still underexploited. In this document, we present the assessment of Standard PRISMA Level 2 (L2) products, distributed by the Italian Space Agency (ASI), and data derived from two atmospheric correction (AC) processors, ACOLITE and POLYMER, adapted for processing PRISMA Level 1 (L1) products, using in situ reflectance from autonomous multispectral and hyperspectral radiometer systems, such as AERONET-OC and WATERHYPERNET. We analysed a total of 79 PRISMA images, acquired from July 2019 to March 2024 over six sites: Acqua Alta Oceanographic Tower (AAOT) in the Northern Adriatic Sea, Galata and Section-7 Platform in the Black Sea, Casablanca Platform in the Western Mediterranean Sea, Boussole Buoy in the Ligurian Sea and L4 Scientific Buoy in the Western English Channel.