Estimation of the raindrop-size distribution at x-band using specific differential phase and differential backscatter phase

At X-band, the propagation effects such as attenuation and differential phase are more pronounced than at S- or C-band. Furthermore, already in moderate rain the scattering regime is not exclusively Rayleigh which leads to the presence of the differential backscatter phase. Particularly the stronger attenuation but also the differential backscatter phase at X-band are usually regarded as deteriorating effects. However, we can also change our perspective, and see them as a valuable carrier of microphysical information. In this contribution we introduce a new method to estimate the raindrop-size distribution from polarimetric X-band weather radar measurements using the specific differential phase and the differential backscatter phase. This new method is successfully applied to data from IDRA, the polarimetric X-band weather radar of IRCTR, TU Delft, that provides continuously since three years measurements from the top of the 213 m high tower at the meteorological observatory at Cabauw, The Netherlands.