Abstract:In order to investigate microphysical characteristics in hailstorm, this paper uses the dual-polarization radar and raindrop spectrum data, as well as the hydrometer classification algorithm to analyze a hail event that occurred in Mount Taishan on 1 June 2020. The distribution features of radar variables, hydrometer and the raindrops in the region around the Mount Taishan Station are obtained when the hailstorm cloud passes through the Mount Taishan. The results show that when the front edge of hailstorm began to affect the Mount Taishan Station, the large gradient area of reflectivity (ZH) was next to the Mount Taishan Station coinciding with differential reflectivity (ZDR) arc position. The particles identified in ZDR arc were mainly composed of abundant big raindrops, which were formed by melting graupel particles over Mount Taishan Station. The structure of the raindrop spectrum was double-peak, and the greater contribution to precipitation was from 2-3 mm particles. When the main body of the hailstorm cloud influenced the Mount Taishan Station, there occurred three-body scattering echo in radial front of the station and overhang echo over the station. The particles in the vicinity of the station were mainly identified as hail. On the south side of Mount Taishan Station, there was the bounded weak echo region (BWER), where the convergent ascending motion was enhanced. The BWER was semi-surrounded by the large value of ZDR (ZDR ring), and the particles in ZDR ring were mainly identified as big drops and hail, mixed with small amount of graupel and wet snow. The contoured frequency by altitude diagram (CFAD) shows that the ice phase process was enhanced. The hail particles under the -10℃ were mainly formed by the graupel particles between -10℃ layer and 0℃ layer riming the big drops and light rain particles carried by updrafts. These particles could not fall and collide to form larger precipitation particles during this period. Therefore, the structure of the raindrop spectrum became single-peak. The most contribution to precipitation was made by 14-16 mm particles. When the hailstorm cloud left the Mount Taishan Station, CFAD shows the ZH corresponding to the high frequency region decreased, the ice phase process was weaken, and the efficiency of the cold cloud droplets attached to the ice crystals to convert into graupel was reduced. A large number of ice crystals and dry snow particles were identified above Mount Taishan Station, where the feature of the stratiform cloud precipitation appeared. The structure of the raindrop spectrum became double-peak again， and the second peak value of particles was 2-3 mm, which contributed more to the precipitation.