A Semi-empirical Algorithm of Water Transparency at the Green Wavelength Band of Optical Remote Sensing

This study employed water transparent characteristics from the Gulf and archipelago of Finland and the corresponding data sets of optical sensors at the green wavelength band to estimate Secchi disk depth (SDD). The SDD is one major optical measurement of water transparency in the study area, where the coastal waters are dominated by absorption from both dissolved and particulate organic matter since the Gulf is optically dominated by scattering from suspended sediments. Concurrent in situ measurements, Landsat TM and simulated SeaWiFS data were obtained in August 1997. The results show that the SDD from the narrow green bandwidth (20 nm) data of simulated SeaWiFS is slightly better than the SDD from the broad green bandwidth (80 nm) data of TM using the semi-empirical algorithm developed in the study. The study of water transparent characteristics in the area still needs to be further investigated using SeaWiFS, MODIS and MERIS in the future.