Retrieval of raindrop size distribution using C-band polarimetric radar measurements

The three parameters(intercept, shape, slope parameters) of the gamma function which specify raindrop size distribution(RSD) are retrieved from C-band linear polarimetric radar of BMRC, Australia. The RSD parameters are determined by the method which minimize a sum of variances between simulated and observed polarimetric variables; horizontal reflectivity(Zhh), differential reflectivity(Zdr), and specific differential phase(Kdp). A relationship between the intercept and shape parameters is used as a constraint. T-matrix algorithm is used to simulate the radar variables, and the retrievals are compared with RSD parameters determined from Joss-Waldvogel type disdrometer data. Some preliminary results show that the retrieved RSD parameters are well agreed with the disdrometer data. In addition, the rainrate calculated from the retrieved parameters shows good agreement with the disdrometer rainrate compare to the rainrate obtained from R(Zhh), R(Zhh, Zdr), and R(Kdp) relationships.