Modeling Snow Volume Backscatter Combining the Radiative Transfer Theory and the Discrete Dipole Approximation

A new method is developed to model the volume backscattering from dry snow. The model is a combination of the exact field approach and zeroth order vector radiative transfer theory. The field approach is used to define the scattering characteristics in a single almost indefinite small snow volume unit and the calculation is realized with discrete dipole approximation (DDA). The radiative transfer theory (RT) is utilized by defining a homogenous snow layer from the averaged scattering characteristics and combining different layers together forming a vertical structure of a snow pack. Because of the DDA the presented model takes into account all multiple reflections and all polarizations inside the snow volume. The scattering amplitude values calculated with the DDA method and according to Mie theory are compared to together. Some results for a homogeneous snow layer are presented for both cubical and needle shaped snow grains.