15:00–15:15 | ABSTRACT 1280
SPECTRAL FACTORS FOR THE REMOVAL OF GLINT PERTURBATIONS IN ABOVE-WATER RADIOMETRY
Spectral factors for the removal of glint perturbations in above-water measurements (so-called rho-factors) were theoretically computed for representative ocean and lake color observation conditions accounting for spectral and atmospheric dependences. Simulations were performed by coupling the highly accurate plane-parallel FEM scalar code with the 3D MOX Monte Carlo code. With specific reference to the above-water measurement geometry recommended for the validation of satellite aquatic radiometric products, rho-factors were computed for the water-surface reflection of the total sky-radiance (rho_T), as well as its direct (rho_D) and diffuse (rho_d) components, thus allowing to separately investigate sun- and sky-glint contributions. While the distribution of rho_T is extremely skewed due to sun-glint, the distribution of rho_d is nearly symmetric, with a clear wind-driven multi-modal behavior. Deviations with respect to average atmospheric conditions at 551 nm are characterized by a mean of +2.7% and a standard deviation of 31%, for rho_T, and by a mean of -0.5% and a standard deviation of 3.9%, for rho_d. Acknowledging the accurate quality-control procedure implemented to filter out measurements affected by appreciable sun-glint, the impact of computed rho_d factors on the processing of AERONET-OC normalized-water leaving radiance was analyzed using collocated in-water reference data acquired at the Aqua Alta Oceanographic Tower in the northern Adriatic Sea. Investigations were further extended to various AERONET-OC sites representative of diverse optically complex waters. On the basis of these results, newly computed rho_d factors for the removal of sky-glint are proposed for AERONET-OC Version 4 processing.
Barbara Bulgarelli, EC-JRC, [email protected], https://orcid.org/0000-0002-9668-2469
Giuseppe Zibordi, NASA-GSFC, [email protected]
Davide D’Alimonte, Aequora, [email protected]
Tamito Kajiyama, Aequora, [email protected]
