Estimation of the attenuation coefficient of the water body using polarimetric observations

摘要

The degree of polarization (DOP) of the underwater light field in oceanic waters is, as follows from the vector radiative transfer equation and has been shown experimentally for a long time [1], related to the single scattering albedo of suspended particles. The single scattering albedo, in turn, is given by the ratio of the scattering coefficient to the attenuation coefficient (or 1 - the ratio of the absorption coefficient to the attenuation coefficient). Knowledge of the single scattering albedo and of the particulate scattering matrix permits solution of the radiative transfer equation for the ocean body. This then opens up the possibility for estimation of attenuation coefficients from measurements of the Stokes components of the upwelling underwater light field which is not possible from unpolarized measurements of the remote sensing reflectance. Results of radiative transfer calculations are presented. We simulated multiple underwater polarized light fields (for the whole visible spectrum) using a vector radiative transfer code with the purpose of obtaining a parameterization of this relationship for different viewing geometries (different solar and zenith/azimuth viewing angles) and in various water conditions (i.e. various IOPs).