Calibration of Differential Reflectivity on the X-band weather radar

In this paper, calibration of differential reflectivity for improving polarimetric application is emphasized. Existed calibration methods which use test signals, solar radiation, natural precipitation, and ground scatters are tested on the China New Generation Doppler Weather Radar/X-band Dual-polarization (CINRAD/XD). Experimental calibration observations reveal that dynamic error sources come from active receiver channel .A suitable calibration procedure for actual operation is designed. Based on calibration result, real-time correction Procedure of differential reflectivity computes compensation values for varied SNR (signal noise ratio) ranges. It need to be corrected unless systematic bias is less than calibration accuracy. There are two schemes to accomplish bias correction, one is adding a set of hardware to adjust signal gain or phase shift of two receiver channels, another is programming to offset bias within signal processor .It is analyzed that hardware scheme is not suit for tiny adjustment of gain difference of two receiver channels , however, it is feasible that software programming is used to offset systematic bias. With correction, the whole linear dynamic range of two receiver gain difference will be under 0.2dB which is better accuracy for precipitation estimation and hydrometeor classification.