The EU Copernicus program, which comprises the operational Sentinel-2 and -3 satellite missions, offers the opportunity for long-term observations of the aquatic systems to support global environmental and climate research, as well as the development, implementation and monitoring of EU legislations to promote ocean protection and water resilience.
Satellite missions delivering fit-for-purpose aquatic data require comprehensive calibration and validation activities to ensure the indirect calibration of space-based sensors and the validation of derived data products, respectively. These activities heavily rely on accurate in situ reference measurements, which in turn depend on metrology principles, state-of-the-art measurement techniques and cutting-edge technology.
Since the initiation of operational Ocean Colour (OC) missions in 1997 with the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) by the US National Aeronautics and Space Administration (NASA), the Joint Research Centre (JRC) has played a pivotal role to sustain the necessary calibration and validation activities. This included the development of specific expertise and the establishment of focussed measurement programs and infrastructure, which are now supporting the ongoing Copernicus missions for the monitoring of both oceanic, transitional and fresh waters.
This work presents the recently developed “HYperspectral Drone-based system for above-water Radiometric Acquisitions” (HYDRA), which performs spatially-distributed above-water radiometric measurements to specifically support the validation of satellite aquatic data products. By relying on well-established measurement methods and a class of widely used hyperspectral radiometers, HYDRA includes a drone-platform allowing to quantify the radiance from the water, and a ground-station to measure the complementary radiometric quantities required to determine the radiance emerging from the water (the so-called water-leaving radiance), which carries information on suspended and dissolved optically significant materials (e.g., phytoplankton).
With the aim of transferring this know-how to the wider user community, this Technical Report provides details on HYDRA, including the applied measurement method, the system components, an assessment of the data products, and finally the essential technical details.
SCIUTO Pietro;
ZIBORDI Giuseppe;
BULGARELLI Barbara;
TALONE Marco;
BERTHON Jean-Francois;
2025-12-03
Publications Office of the European Union
JRC144849
978-92-68-34806-2 (online),
OP KJ-01-25-627-EN-N (online),
https://publications.jrc.ec.europa.eu/repository/handle/JRC144849,
10.2760/0247707 (online),
