Parameterization of the scattering and absorption properties of individualice crystals

We present parameterizations of the single-scattering properties for indivi dual ice crystals of various habits based on the results computed from the accurate light scattering calculations. The projected area, volume, and sin gle-scattering properties of ice crystals with various shapes and sizes are computed for 56 narrow spectral bands covering 0.2-5 mu m. The ice crystal habits considered in this study are hexagonal plates, solid and hollow col umns, planar and spatial bullet rosettes, and aggregates that are commonly observed in cirrus clouds. Using the observational relationships between th e aspect ratios and the sizes of ice crystals, we can define the three-dime nsional structure of these ice crystal habits with respect to their maximum dimensions for light scattering calculations. The volume and projected are a of ice crystals, expressed in terms of the diameters of the corresponding equivalent spheres, are first parameterized by employing the ice crystal m aximum dimensions. Further, various analytical expressions as functions of the effective dimensions of ice crystals have been developed to parameteriz e the extinction and absorption efficiencies, asymmetry factor, and the tru ncation of the forward peak energy in the phase function. The present param eterization scheme provides an efficient approach to obtain the basic scatt ering; and absorption properties of nonspherical ice crystals.