Geodaysit 2023

This study provides an overview of main findings achieved by exploiting the hyperspectral products provided by PRISMA in the visible near infrared wavelength range (VNIR), for aquatic ecosystems mapping. To this aim, the quality of PRISMA L2 products, distributed by ASI and already atmospherically corrected, is assessed on the basis of corresponding in-situ measurements at twenty inland and coastal water sites representing a wider range of optical properties of water. For a subset of sites, where L2 products showed low accuracies, the results provided by different atmospheric correction codes (e.g., ACOLITE) are added. The results show that the PRISMA L2 products are sub-optimal for estimating water quality parameters, apart from very turbid waters or clear-shallow waters, while ACOLITE would generally be more accurate in reproducing the spectral shape of in-situ hyperspectral data. A series of use cases are then presented to demonstrate the performances of a pre-defined series of algorithms (i.e. bio-optical modelling inversion, band-ratios, machine learning) for deriving bio-physical parameters in optically complex waters from PRISMA. The retrieval of water quality parameters is performed for a variety of water types corresponding to lakes of different trophic status, coastal waters with significant depth profiles and ecosystems characterized by different hydrogeochemical and ecological processes. The presented use cases include the simultaneous retrieval of phytoplankton pigments (e.g., concentration of chlorophyll-a and phycocyanin) total suspended matter with separation of organic and inorganic fractions, yellow substances, the mapping of fractional cover of bottom types, as well as of emergent macrophytes biomass. For some of these parameters the synergy of PRISMA with operational multispectral sensors (e.g., Sentinel-2) are presented, while an outlook for advancing the estimation of water quality parameters with PRISMA is finally discussed.