Abstract:To promote the application level of hydrometeor classification for Chinese Doppler polarimetric radar, based on the hydrometeor classification algorithm (HCA) developed by the National Severe Storm Laboratory (NSSL) of the United States, we design an optimum algorithm, named HCA-Opt, by adding the amendatory identification for the hydrometeor in hail and three-body scatter area, using the temperature of the numerical weather model analysis field to detect the location of the melting layer, and integrating restricted condition of vertical distribution for all hydrometeors. HCA-Opt is utilized to analyze the distribution characteristics of hydrometeor during a hailstorm cloud weather in Zhangqiu of Jinan City on 9 July 2021, and the location of the hail and the hydrometeor classification result are verified. The conclusions are as follows. The type of hydrometeor wrongly recognized as ground clutter by the HCA in the hail and the three-body scatter region can be correctly identified by the HCA-Opt. HCA-Opt can use the temperature from model analysis field to accurately identify the height of melting layer, solving the defect that the melting layer could not be detected by the algorithm in severe convective weather in HCA. Compared to HCA, the vertical distribution of hydrometeor identified by HCA-Opt is more reasonable. Besides, the classification result retrieved from the HCA-Opt can better describe the spatial distribution of hydrometeor at newborn and hailfalling stages of hailstorm, and initially reflect the characteristics of phase transformation at different heights. Through the verification, the reliability of the moderate (light) rain and graupel identified by the HCA-Opt is the highest, while that of the crystal and wet snow is lower, and easy to be mixed with the dry snow. Overall, the HCA-Opt can improve the skill of hydrometeor identification to certain extent, provide indicative information for warning and detecting the hailfalling area and have a good operational application prospect.