A nonspherical cloud scattering database using aggregates of roughened bullet rosettes model for the advanced radiative transfer modeling system (ARMS)

A nonspherical scattering look-up table contains optical properties of five hydrometeor types: rain, cloud water, cloud ice, graupel, and snow, for the Advanced Radiative Transfer Modeling System (ARMS) at frequencies below 220 GHz. To compute the single-scattering properties of solid cloud particles, the discrete dipole approximation (DDA) method is employed, modeling these particles as aggregated roughened bullet rosettes. The bulk optical properties of the cloud layer are derived by integrating the single-scattering properties with a modified Gamma size distribution, specifically for distributions with 18 effective radii. The bulk phase function is projected onto a series of generalized spherical functions, applying the delta-M method for truncation.