Distinct meteorological drivers for hot-dry, warm-humid, and hot-humid heatwave–ozone events in China

Co-occurring heatwaves and surface ozone (O₃) pollution events (HWOPs) are increasingly threatening public health and socioeconomic stability. Given that both temperature and humidity are fundamental drivers of heat stress, we categorized summer HWOPs across China during 2005–2022 into hot-dry, warm-humid, and hot-humid types, and found distinct meteorological drivers. Their spatial distributions exhibit clear regional preferences—hot-dry events dominate North China, warm-humid and hot-humid events cluster in the Yangtze River Basin and South China. Hot-dry events typically occur under clear skies, low soil moisture, strong solar radiation, and a stable boundary layer. Warm-humid events develop under moderate humidity and elevated latent heat flux, supported by subtropical highs and mid-level dry air intrusion that suppress convection and prolong near-surface moist static energy accumulation. Hot-humid events combine features of both regimes, driven by early-developing, persistent ridges over eastern China, accompanied by strong wave activity flux convergence and sustained upper-level divergence. Temperature and humidity thus emerge as key regulators of surface energy balance, boundary-layer stability, and synoptic evolution, explaining the contrasting trends and impacts of the three HWOP types. These insights improve understanding of compound climate–pollution extremes and support more effective risk mitigation.