Angular variation of remote-sensing reflectance and the influence of particle phase functions

Using three different particle phase functions, subsurface remote-sensing reflectance (r_rs) are simulated by Hydrolight, with the Sun positioned at 10deg, 30deg, and 60deg from zenith, respectively. The values of r_rs at six angles are compared with that at nadir, so do the spectral ratios of r_rs(440)/r _rs(560). It is found that, generally, r_rs values differ the most when the Sun is at 60deg and the sensor is partially facing the Sun. For all sun angles, observation angles, and particle phase functions in this study, however, the ratios of r_rs(440)/r_rs(560) only show limited variations. These results suggest that remote-sensing algorithms based on such kind of ratios are generally applicable to r_rs observed in the remote-sensing domain