POSTER Session 4

ESTIMATION OF SECCHI DISK DEPTH BASED ON PRISMA IN VENICE LAGOON, ITALY

PANDA-WATER (PRISMA products AND Applications for inland and coastal WATER) project aims to provide a set of innovative products from PRISMA hyperspectral imagery over inland, transitional, and coastal waters. Secchi disk depth (ZSD) is one of the products of interest as a proxy of water transparency, which is a good indicator for inland and coastal water quality. Semi-analytical model was applied to PRISMA data to obtain high-spatial-resolution maps of water clarity in Venice Lagoon. In details the methodology comprises that: i) total absorption (a) and backscattering (bb) coefficients were retrieved from remote sensing reflectance (Rrs) with Quasi-Analytical Algorithm; ii) the diffuse attenuation coefficient (Kd) was obtained from a and bb following the semi-analytical Kd model; iii) ZSD was calculated as minimum Kd. This model was applied to “PRISMA-like” Rrs calculated from in situ Rrs by the PRISMA spectral response function, and the results were validated with in situ ZSD measurements. A good correlation was found between the estimated and measured ZSD (N = 364, R2 = 0.76, RMSE = 0.69 m). The model was further applied to PRISMA imagery both Level 2C (L2C) and atmospherically corrected with ACOLITE/DSF. The results show that: (1) the obtained spatial distribution of ZSD is quite consistent with in situ measurements (N = 12, R2 > 0.74, RMSE < 0.55 m); (2) ZSD derived from PRISMA ACOLITE/DSF is more reliable in waters close to land, because PRISMA L2C is likely affected by adjacency effects.

*Congju Fu, Consiglio Nazionale delle Ricerche, Istituto di Scienze Marine (CNR ISMAR), Italy, [email protected], https://orcid.org/0009-0003-4414-2430

Gian Marco Scarpa, Consiglio Nazionale delle Ricerche, Istituto di Scienze Marine (CNR ISMAR), Italy, [email protected]

Vittorio Ernesto Brando, Consiglio Nazionale delle Ricerche, Istituto di Scienze Marine (CNR ISMAR), Italy, [email protected]

Federica Braga, Consiglio Nazionale delle Ricerche, Istituto di Scienze Marine (CNR ISMAR), Italy, [email protected]

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