Change Features of Cloud Microphysical Structure of Severe Convective Storm Clouds By Polarimetric Radar Observation

A large-scale severe convective storm clouds and precipitation event occurred in eastern Beijing on 22^nd August 2015, and an artificial hail-suppression seeding operation aimed at this event was conducted. In this paper, the Change Features of the severe storms event was analyzed, using both the reflectivity from S-band operational weather radar and the retrieved cloud microphysical structure identified by an X-band polarimetric radar. It is found that the intensity decreasing trend of dealt storm cells can be significantly accelerated after artificial seeding. The seeding leads to a rapid range expansion of graupel and a gradually expansion of snow, decreasing the range of hail in the cloud significantly at the late stage of a storm cell, which illustrates that seeding can indeed change the microphysical process in severe convective storms. Meanwhile, the area of vertical oriented ice crystal in the high level of a severe storm has a corresponding relation with the region of negative differential reflectivity (Z_DR) and negative specific differential phase (K_DP).