Characteristics of atmospheric vertical structure during a freezing rain process in Changsha, Hunan Province based on Ka-band cloud radar

In view of the lack of fine ground detection data of freezing rain clouds, using the high sensitivity of Ka band cloud radar for small-scale precipitation particle detection, combined with ground meteorological automatic observation equipment, a joint quantitative detection experiment was carried out on the vertical structure of cloud in the whole process of freezing rain in Changsha, Hunan Province from 00:00 on February 5 to 24:00 on February 7,2024 (for simplicity, it is called "2.5" process). On the basis of the quality control of the basic data, the vertical spatiotemporal structure of the four physical parameters of cloud reflectivity factor Z, radial velocity V, velocity spectral width W and linear depolarization ratio LDR in the whole process of freezing rain generation and dissipation were successfully obtained by using the echo feature processing method. The analyzed results show that the type of this freezing rain belongs to the mechanism of ice phase formation, and there are obvious melt layer characteristics, and the Z, V, W, and LDR increase significantly from 3km height to the ground, and the peak LDR reaches -15dBz~-20dBz.the vertical profile structures of Z, LDR and V before and after the freezing rain are more similar than those of ordinary winter sleet, however ,the vertical profiles of V and W are quite different from those of sleet. The results are helpful for the identification of the formation mechanism of freezing rain and the extraction of freezing rain feature parameters and early warning.