海南岛一次强飑线系统演变的双偏振特征分析.

A long-lived squall line system caused strong winds and heavy rainfall in the central and northern parts of Hainan Island on April 22, 2020. The present study analyzed the evolution of the squall line system by comparing conventional meteorological data with dual-polarization radar detection data. The results indicated that the squall line occurred on the northwestern edge of the subtropical high-pressure zone, with a quasi-stationary front controlling the ground. Mainly affected by the warm and humid southwest airflow, the intensity of cold air was generally weak. The ground convergence line and suitable thermal conditions acted as environmental triggers. Throughout the evolution of the squall line, the radar combined reflectivity consistently maintained a strong value with large areas exceeding 55 dBZ. However, the differential reflectance (ZDR) of the cloud system exhibited a large area exceeding 5 dB and extended up to 8-9 km vertically during the initial formation of the squall line (16:20-16:43). During the squall line process, the ZDR over Haikou and Wenchang stations peaked approximately 12 minutes before ground precipitation and decreased as precipitation increased. The KDP was closely correlated with precipitation intensity. Additionally, the frequency of ground lightning increased in the early stage of precipitation, peaking approximately 6 to 12 minutes before ZDR and about 24 to 48 minutes before KDP. [ABSTRACT FROM AUTHOR]