Time Evolution Characteristics of Narrow Bipolar Event in Pearl River Delta Region

China's South China region is a high-incidence area for lightning, making lightning protection efforts crucial. The generation of Narrow Bipolar Events (NBEs) is closely related to thunderstorm activity. In this study, the temporal evolution characteristics of NBE activity were analyzed in detail using data from 10 thunderstorms that occurred in the Pearl River Delta (PRD) area of Guangdong province in May 2014. The results show that NBE activity mostly began after 11:00 and ended before 20:30, with the peak activity period concentrated between 14:00 and 18:00 in the 10 thunderstorms. The most intense phases of NBE activity were mainly distributed in the early and late stages of occurrence and development, while the active phase of NBE activity accounted for approximately one-fifth of the entire process. The average ratio of positive to negative polarity NBEs throughout the NBE activity process in the 10 thunderstorms was approximately 7:3.