Implementation of polarization into a 3D Monte Carlo Radiative Transfer Model: Results and Applications

Non-spherical particles scatter and polarize solar radiation depending on their shape, size, chemical composition and orientation. In addition, such information is crucial in radiative transfer modeling. Therefore, in this study, the implementation of polarization in a three-dimensional (3D) radiative transfer model is introduced and its validation through benchmark results. The model is based on the statistical Monte Carlo method (in the forward scheme) and takes into account multiple scattering and the polarization state of the monochromatic radiation. It calculates column-response pixel-based polarized radiative densities for 3D inhomogeneous cloudy atmospheres and is hence best suited for use in remote sensing applications. To this end, the model can be used to explore the potential of remote sensing techniques to distinguish between spherical and non-spherical particles on the one side and coarse mode dust particles and ice particles on the other side. Applications to sun-photometer-based observations of downwelling solar radiances polarized by Saharan dust and ice particles will be discussed. Moreover, 2D Monte Carlo radiative transfer runs for lidar-based Saharan dust cloud fields from SAMUM experiment will be presented.