Unmanned aerial vehicles (UAVs), commonly referred to as drones, offer an innovative alternative to in situ measurements performed from fixed structures or ships. Within such a general framework, this work presents the “Hyperspectral Drone-based system for above-water Radiometric Acquisitions” (HYDRA), conceived for measurements specifically supporting the validation of satellite aquatic radiometric data products. By relying on consolidated measurement methods and a class of extensively characterized hyperspectral radiometers, HYDRA comprises the UAV platform allowing to quantify the radiance from the water LT and a complementary ground-based station to measure the sky-radiance Li and the downward irradiance ES . Field measurements to evaluate the performance of the system were carried out in the northern Adriatic Sea in the proximity of the Acqua Alta Oceanographic Tower (AAOT) during almost ideal conditions determined by sun clear from clouds, sea state lower than 2 (WMO scale), cloud cover lower than 2 oktas, and wind speed below 3 m s−1. During these tests, HYDRA LT measurements were complemented by independent and concurrent LT measurements performed at the AAOT using a hyperspectral radiometer belonging to the same class as that operated on the UAV. Matchups of HYDRA and AAOT LT showed mean spectral differences generally ranging between 0% and +1% in the 400–580-nm interval and within ±1% in the 580–700-nm interval. The same differences characterized HYDRA and AAOT R RS spectra as a result of the application of the same Li and ES values.

SCIUTO Pietro;  ZIBORDI Giuseppe;  BULGARELLI Barbara;  TALONE Marco;  BERTHON Jean-Francois; 

2026-06-26

AMER METEOROLOGICAL SOC

JRC143647

1520-0426 (online),   

https://journals.ametsoc.org/view/journals/atot/43/6/JTECH-D-26-0006.1.xml,    https://publications.jrc.ec.europa.eu/repository/handle/JRC143647,   

10.1175/JTECH-D-26-0006.1 (online),