Regional Variability in the Structure and Microphysical Characteristics of Hail Clouds over China Based on GPM Observations and ERA5 Reanalysis

Hail is one of the most destructive warm-season severe convective hazards in China, yet the structure and microphysical evolution of hail-bearing clouds vary markedly among regions. Using GPM DPR/GMI observations together with ERA5 reanalysis during the warm seasons of 2020–2025, we identified 817 hail cloud systems across five representative hail-prone regions of China, namely Northeast China (NE), North China (NC), South China (SC), Southwest China (SW), and the Tibetan Plateau (TP), on the basis of the flagHail indicator. We then compared their macroscopic structure, vertical microphysical characteristics, organization scale, and environmental setting within a unified framework. The results reveal pronounced regional heterogeneity. Hail cloud systems in SC and SW exhibit higher echo-top heights and larger ice water paths, together with the strongest downward enhancement of reflectivity and particle size within the key ice-growth layer between 0 ∘C and −20∘C, indicating a deep moist-convective regime. By contrast, hail cloud systems in NC and NE more often develop into organized and horizontally extensive systems under stronger vertical wind shear, consistent with an organization-enhanced regime. Hail cloud systems over TP are characterized by high cloud tops, low hydrometeor content, and weak low-level growth, which together define a plateau-constrained regime. Environmental analyses indicate that these regional contrasts are jointly regulated by thermodynamic instability, vertical wind shear, and topographic forcing. These findings provide a physically consistent basis for satellite-based hail monitoring and region-specific hail warning over China.