Computation of the Optical Properties of Preferably Oriented Ice Crystals from a Combination of the Discrete-Dipole-Approximation and Physical-geometric Optics Hybrid Methods

Modeling the single-scattering properties of preferably oriented ice crystals in the atmosphere has important implications to climate study and remote sensing applications. In this study, we employ a combination of the discrete-dipole-approximation (DDA) for small size parameters, and physical-geometric optics hybrid methods for moderate and large size parameters to investigate the dependence of the optical properties of preferably oriented ice crystals on aspect ratio, particle size and refractive index. Based on representative numerical calculations, we discuss the treatment of some physical processes, which determines the accuracy and efficiency of physical-geometric optics hybrid method. Furthermore, an optimal algorithm is proposed to calculate the optical properties of oriented ice particles.