Inverse scattering problem for mixed-phase and ice clouds. I. Numerical simulation of particle sizing from phase-function measurements.

We propose a new method of particle size retrieval for mixed-phase and ice crystal clouds. The method enables us to identify each component of a bicomponent cloud composed of water droplets and ice crystals and to retrieve a size distribution separately for each cloud component. We explore the method's capability by using sythetic multiangular data of scattered-light intensity. We model cloud microphysical characteristics by assuming two noninteracting cloud components, such as liquid or supercooled droplets and cubic or hexagonal ice crystals, with regular simple geometrical shapes as first approximation. The sensitivity of the method is tested for different relative concentrations of the cloud components that are varied over a wide range. First, we investigate the applicability limit of the single-component cloud approximation in retrieving particle size distributions of a bicomponent cloud. Second, we test the method to retrieve size distributions simultaneously for both components in mixed-phase clouds, and we discuss the conditions of its applicability.