A Statistical Index of Bio-Optical Seawater Types

Water-type (WT) definition as a function of bio-optical properties has relevance to the exploitation of satellite ocean color data because it may provide a mean to optimize the atmospheric correction process or select the most appropriate bio-optical algorithm for the determination of optically significant constituents in seawater. Within such a framework, this paper defines a WT index assuming the existence of two extreme conditions. On one side, there are waters with optical properties totally depending on the phytoplankton component. On the other side, waters characterized by fully unrelated bio-optical quantities. The index of intermediate WTs is then defined on a statistical basis, and the resulting scheme is applied to a set of experimental data collected in an optically complex coastal region. Finally, in view of supporting remote sensing applications, a neural network algorithm is implemented to identify WTs using the normalized water leaving radiance.