Dependence of the diffuse reflectance of natural waters on the sun angle

Abstract

Through Monte Carlo simulation, the variation of the diffuse reflectance of natural waters with sun angle is found to be dependent on the shape of the volume scattering function (VSF) of the medium. It is shown that single scattering theory can be used to estimate the reflectance—sun angle variation given the VSF—and, conversely, the VSF over a limited range of scattering angles can be estimated from measurements of the variation of the reflectance with sun angle. The complex variation of reflectance with the incident illumination and surface roughness can be reduced to the variation of a single parameter: the downwelling distribution function in the absence of scattering. These observations are applicable to all but the most reflective of natural waters.