Toward Better Constrained Scattering Models for Natural Ice Crystals in the Visible Region

In this work, we introduce a method for constraining the optical scattering models of natural ice crystals based on in-situ measurements. Specifically the measured angular scattering functions for ice crystals can be used to compute a set of the asymmetry parameter (g) and the corresponding complexity parameter (Cp). It is demonstrated that the g-Cp relation can give valuable information on the morphology of ice crystal. The validity of the methods is shown from theoretical perspectives and the geometric-optics ray-tracing simulations. As an application, we investigate rimed ice crystals from in-situ measurements and found that (a) the Cp parameter is very well correlated with the surface riming degree and (b) only those models with both roughness and internal scattering can explain the observed g-Cp relation for rimed particles.