This study presents an approach for the determination of the trophic parameters Secchi depth and chlorophyll-a from hyperspectral airborne casi and HyMap data with multi-temporal validity. Based on in situ water sampling and reflectance measurements, algorithms have been developed: for Secchi depth the area between a base line and the spectrum from 400 nm to 750 nm was calculated and correlated to the Secchi depth measured in situ; chlorophyll-a concentration was quantified using the reflectance ratio at 705 nm and 678 nm showing a linear relationship to chlorophyll-a content from laboratory spectro-photometric measurements. The algorithms have been adapted to the spectral characteristics of the airborne sensors and applied to these data recorded in September 1997 and 1998, May and June 1999. The validation using independent in situ reference showed mean standard errors of 1.2 to 1.3 m for Secchi depth and of 10.2 to 10.9 μg/l chlorophyll-a.
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