Estimation of Secchi-disk Depth Semi-analytically from Landsat-8 Data

The newly developed analytical model [Lee et al., RSE, 2015] for Secchi disk depth (Zsd) is modified for application with Landsat-8 measurements. Also, to implement the quasi-analytical algorithm (QAA) for the derivation of absorption and backscattering coefficients from Landsat-8 data, which are key optical properties for the estimation of Zsd, the representative wavelengths of the Landsat-8 bands in the visible domain were determined; so were the absorption and backscattering coefficients of pure water at these bands. The semi-analytical scheme was further applied to a Landsat-8 image collected in an estuarine to obtain high-spatial resolution Zsd map, and the obtained results were found quite consistent with numerous visual perceptions. These results indicate the possibility to generate reliable high-resolution water clarity product of bays, estuaries, and lakes from Landsat measurements with a unified mechanistic system.