Spatial and temporal characteristics of warm season convective storms over the southeastern coast of China

Abstract

Abstract Utilizing observational data from the Xiamen radar station during the warm season of 2015–2018 (May to September), this study employs a convective storm identification algorithm to statistically analyze the spatiotemporal distribution, diurnal propagation, and seasonal variability of convective storms over the southeastern coast of China. Key findings include: (1) Significant monthly variations in convective storm frequency, with peaks in August over land areas of Zhangzhou and Xiamen's northwest, and offshore southeast of Xiamen. Seasonal circulation patterns, particularly the subtropical high and northern high-level troughs, drive these variations. (2) Large-scale convective storms are most frequent, while small-scale ones are less common. Mid-deep convective storms dominate, particularly in southern Zhangzhou and southwestern mountainous Quanzhou, whereas shallow convective storms are rare and scattered. High-frequency areas correlate with higher terrain, underscoring the influence of topography on storm occurrence and development. (3) Hovmöller plots reveal a bimodal diurnal pattern in propagation of storms for July and August, with peaks in the daytime and late night. Daytime storms propagate from coastal to higher terrain areas, while nighttime storms maybe driven by enhanced vertical wind shear. These findings enhance the understanding of convective storms in the region and highlight the crucial role of the circulation background, terrain, and prevailing wind directions in the spatiotemporal characteristics of warm season convective storms in southeastern China.

Keywords

• Convective storms
• Spatiotemporal distribution
• Diurnal propagation
• Circulation background