Optical classification of optically complex waters around China

For optically complex waters, the optical classification was suggested to be a good solution to improve the retrieval of biogeochemical products, and more appropriate for large-scale complex waters than classical regional waters. Around China there are turbid lakes, complex rivers and highly contrasted coastal regions, so the study provided an applicable classification strategy for characterizing the optical variability of the optically complex waters of Chaohu Lake, Three Gorges, Dianchi Lake, Taihu Lake, and Huanghe estuary waters. An improved K-means algorithm based on spectral angle distance was used to cluster an in situ data set of remote sensing reflectance spectra (447 stations) into five optical classes. The combination of the characteristic wavelengths, a set of features of spectra to distinguish the waters into five optical types was provided. This work provides an effective set of features of spectra to divide the optically complex waters around China and the potential of class-specific inversion methods for deriving bio-optical products by the satellite images in optically complex waters.