Molkov, A., Fedorov, S., Pelevin, V., Korchemkina, E.
The retrieval of chlorophyll a (Chl a) and total suspended matter (TSM) from Sentinel-2/MSI imagery and in-situ measurements is investigated for the Gorky Reservoir, an inland freshwater ecosystem in Russia. During the algal-bloom period the optical properties of the water are extremely heterogeneous, varying on scales of tens of metres and in time under currents and wind, so traditional station-based sampling is largely uninformative. The authors propose an approach based on simultaneous in-situ measurement of remote-sensing reflectance by a single radiometer and of water constituents by an ultraviolet fluorescence LiDAR, run from a high-speed gliding motorboat. This collected 4087 synchronised LiDAR and radiometric measurements at 8 m resolution in two hours; the part coincident with a Sentinel-2 overpass was used to develop regional retrieval algorithms for Chl a and TSM — the first such work for inland waters of the Russian Federation, transferable to other Volga reservoirs.