Analysis of Hydrometeor Distribution Characteristics in Stratiform Clouds Using Polarization Radar

Using data from X-band dual-polarization radar system set up by the Institute of Atmospheric Physics, Chinese Academy of Sciences, the paper discusses various dual-polarization radar parameters and their physical essence of representing hydrometeors. On the basis of reflectivity and differential reflectivity attenuation correction, the paper analyzes vertical structure and hydrometeor phase distribution structure of stratiform cloud, puts forward methods to position the melting layer and retrieve the vertical temperature profile in combination with the ground temperature. Statistical analysis for specific layers in the stratiform cloud is conducted, and with reference to international C- and S-band radar studies, ranges of X-band radar parameters, i.e. reflectivity, differential reflectivity, specific differential phase shift, and correlation coefficient, for several main hydrometers are acquired. On the basis of above results, hydrometeors are classified using the fuzzy logical method. The results reflect the phase distribution characteristics of stratiform cloud and hydrometeors. Then, possible precipitation mechanism is discussed according to two cases. The retrieved hydrometeor distribution is used to study microphysical processes of precipitation instead of using the radar echo structure. The results verify the three-layer conceptual model introduced by Koo Zhen-Chao (1980) in the 1960s. The studies provide the method for dual-polarization radar application to cloud and precipitation physics studies, and indicate its broad potential application prospect.