Simulation of Ice Particle Density from 0.05 to 0.9 g/cm3

Simulating optical properties of ice particles is challenging but important. Under certain atmospheric conditions, ice particles can grow into very complicated morphologies, including surface roughness, inhomogeneity, and riming structures. Many previous studies use certain kinds of homogeneous medium approximation (e.g., the effective medium approximation) to simulate rimed ice particles and graupel, in which the discrete feature is not included. In this study, we use the more realistic bicontinuous medium to simulate these particles, which has already been used successfully to simulate ground snow. In a bicontinuous medium, the refractive index is discrete from part to part and the density is controlled through changing the internal structure. The state-of-the-art invariant imbedded T-matrix method and improved geometric optics method are used to calculate the optical properties of rimed particles and graupel. The bicontinuous medium approximation results in smaller asymmetry parameter, larger extinction efficiency, and smaller single scattering albedo than the effective medium approximation using the Maxwell-Garnett formula. We will also present retrievals using passive and active satellite observations, and comparisons between bicontinuous medium and effective medium approximations.