Convective initiations (CIs) in western Jiangnan, China, were examined using radar data for April–September, 2018–2021. An integrated approach, combining objective identification and subjective validation, was applied to identify, track, and validate the CIs, producing a CI dataset with high accuracy. Using this dataset, we investigated the spatiotemporal variation and environmental conditions associated with CIs. This revealed distinct seasonal and diurnal patterns of CI events. Spatially, CIs occurred more frequently to the south of the Nanling Mountains and less frequently to the north. Seasonally, they were most frequent from June to August and least frequent in April and September, following a unimodal distribution. The CIs exhibited pronounced convection in the afternoons, particularly from June to August, when most of the CIs occurred between 11:00 and 19:00 local time (LT, UTC + 8h). Terrain significantly influenced the spatial variation in CIs. North of the Nanling Mountains, the CIs occurred near higher mountains, whereas south of the range, they were concentrated near smaller mountains and in coast of Guangdong. Using K-means clustering, those CIs that can develop into Mesoscale Convective Systems were classified into four circulation types: Western Pacific Subtropical High (WPSH) Control type (Type I), WPSH Edge type (Type II), Southwest Airflow type (Type III), and Low Trough Shear type (Type IV). CIs of Types I and II were attributed primarily to afternoon thermal convection, occurring under conditions of high moisture and thermal instability. The triggers for these types of CIs tended to occur near high-elevation terrain. In contrast, Types III and IV were driven primarily by the synergy of abundant moisture conditions and synoptic dynamic factors such as low-level jets, upper-level troughs, and shear lines. These types exhibited higher frequency in the south, with high-frequency CI-trigger zones particularly observed in regions of strong moisture flux convergence and near complex terrains.
Zhenzhen et al. (Sun,) studied this question.