Presenter: Claudia Giardino (National Research Council of Italy)

Description:
This study presents a qualification of imagery data from the PRISMA mission for aquatic applications. A general description of PRISMA is initially provided for presenting the main features of the mission. The standard Level 1 (L1) and Level 2 (L2C and L2D) products, respectively providing the hyperspectral geocoded data-cube of at-the-sensor radiances and of the bottom-of-atmosphere reflectances, with associated estimates of atmospheric properties (e.g. aerosol optical thickness, AOT), are presented for inland and coastal waters. In particular, imagery data are covering several ecosystems distributed globally, depicting a rather wide range of optical properties. PRISMA products are then evaluated based on in situ data (e.g. AERONET-OC, WISPStation), while data collected by Sentinel-2 and Sentinel-3 are also included to align PRISMA with the operational missions largely used in water quality remote sensing. The main outcome of the study is the following: i) the signal-to-noise ratio (SNR) from L1 products over homogenous waters is comparable to Sentinel-2, apart at shorter wavelength; ii) AOTs from L2C products show a lower level of variation respect to AERONET; iii) L2D products in terms of remote sensing reflectance (Rrs) indicates that, even if some applications might be developed with the standard L2D products, an ad-hoc processing might be necessary to include the specific requirements of atmospheric correction of water targets. To the aim specific atmospheric correction techniques (e.g. ATCOR-2) are applied for improving the retrieval of Rrs for some explicative use cases. Based on these findings, some examples of water quality retrieval are presented for a subset of ecosystems (e.g. Italian lakes and coastal lagoons). This study, beside to represent a key element of ASI PRISMA CAL/VAL project, aims to support the studies of aquatic environments for the planned CHIME mission and is involved in the pre-formulation studies of the next-generation PRISMA.