Vector Radiative Transfer in a Vertically Inhomogeneous Scattering and Emitting Atmosphere. Part II: Coupling with Azimuthally Asymmetric Polarized Bidirectional Reflection over Oceans

The reflection of ocean surface is often assumed azimuthally symmetric in the previous vector discrete ordinate radiative transfer (VDISORT) and many other radiative transfer solvers. This assumption can lead to obvious errors in the simulated radiances. In this study, the vector radiative transfer equation is solved with a polarized bidirectional reflection distribution function (pBRDF) for computing the surface-leaving radiation from the lower boundary. An azimuthally asymmetric pBRDF model at visible and infrared bands over oceans is fully coupled with the updated VDISORT model. The radiance at the ocean surface is combined with the contributions of atmospheric scattering and surface properties. It is shown that the radiance at the ocean surface also exhibits a strong angular dependence in the Stokes vector and the magnitudes of I,Q,V increase for a larger azimuthal dependence of pBRDF. In addition, the solar position affects the peaks of sun glitter pattern, thus modulating the signal magnitudes and the angular distributions. As ocean wind increases, the reflection weakens with reduced magnitudes of Stokes parameters and less-varying angular distributions.