Multi-wavelength radar algorithm with Doppler function for the retrieval of cloud microphysics with precipitation

We developed the retrieval algorithm for clouds accompanying precipitation. In order to obtain the vertical structure of cloud microphysics, W-, Ka- and X- band radars with Doppler capability were used. We first considered six different particle types and the scattering properties of the non-spherical ice particles were calculated at these frequencies by using the discrete dipóle approximation (DDA). Then dual wavelength ratios (DWR) and the reflectivity-weighted terminal velocities (Vtz) for the six particle types were estimated. It was found that the DWR for W- and Ka- band radars depended on particle shape, orientation and size when particle effective radius exceeds about 60 urn. DWR for Ka- and X- band radars also showed the similar dependences but for larger size than the DWR for X and Ka band radars. The Vtz also show the strong dependence on shape, orientation and size for large size. The retrieval algorithm consists of two parts; (1) large particle mode from the combination of DWRs and VTzs from W-, Ka- and X- band radars measurements and (2) small particle mode from the radar reflectivity and Vtz from Ka- band. We examined the cloud microphysics from the radar data observed in Niigata in December 2007, in the field experiment of Japanese Cloud Seeding Experiment for Precipitation Augmentation (JACSEPA). Retrievals of microphysics were performed for two cases. The retrieval results were compared with the in-situ data and found some agreement.