Accuracy of the Anomalous Diffraction approximation to light scattering by column-like ice crystals

The wavelength and the particle size effects on the accuracy of ADA (Anomalous Diffraction Approximation) method are discussed by comparing the scattering results between ADA method and Mie theory for spherical particles, which indicates that the ADA accuracy depends mainly on the particle size parameter, and is not sensitive to the condition of | m − 1 | ⪡ 1. The results comparison between ADA method and ray tracing method for hexagonal column-like ice crystal particles shows that within the visible wavelength range, results from both methods agree well, and within the infrared wavelength range, there is large discrepancy for co-albedo result due to different assumptions of the ray path inside the particle.