A Study of Scattering, Backscattering and a Hyperspectral Reflectance Model for Boreal Waters

Some inherent and apparent optical properties and their relations have been studied using data from Finnish, Estonian and Swedish waters during 1997 – 2001 and a hyperspectral model for irradiance reflectance was tested. The measured characteristics were up/downwelling spectral irradiance (Licor Li-1800UW), absorption and attenuation of the water in nine wavelength channels (WetLabs, ac-9), backscattering in six wavelength channels (HOBI Labs Hydroscat 6), Secchi disk depth and the concentration of chlorophyll a, suspended matter and yellow substance. The spectral dependence of the scattering coefficient b was studied in different lakes and in different years. It was found that a power law describes best this dependency. The backscattering coefficient bb and the backscattering probability B were studied using direct measurements and also calculated values. Lastly a hyperspectral model for reflectance was tested with new data and improved parameterization. The model has been developed for interpretation of remote sensing data collected above inland waters. A large data set of Ac-9 and Li-1800UW results was used to test and improve the model, which was run in a forward mode. Key words: scattering, backscattering, reflectance model, optically active substances, water quality, optical remote sensin