Impacts of urbanization on precipitation and thermodynamic–dynamic mechanisms of typhoon

Eastern Zhejiang Province, a highly urbanized coastal region in southeastern China. Urbanization modifies land–atmosphere interactions, yet its influence on rainfall evolution during landfalling tropical cyclones remains unclear. Using Super Typhoon Lekima (2019) as a representative case, this study applies triple-nested WRF simulations to examine urbanization effects on typhoon-induced precipitation under three land-use scenarios: 2001 Urban, 2020 Urban, and 2020 No Urban. Model performance is evaluated using precipitation observations from 236 meteorological stations and best-track data, showing reasonable agreement with a mean track error of 66.64 km and a precipitation correlation coefficient of 0.68. Urbanization induces a stage-dependent rainfall response with spatial heterogeneity. During early landfall, urban areas suppress rainfall by 10–20 mm due to reduced latent heat flux, weakened near-surface moisture availability, and urban-induced dynamic blocking that limits low-level moisture transport. As the storm moves inland, enhanced surface roughness and a “high 2-m air temperature (T₂)–high sensible heat flux (HFX)–low latent heat flux (LH)” energy pattern strengthen instability and convergence, producing 5–10 % higher peak rainfall than the 2001 urban condition. In contrast, natural surfaces sustain higher post-peak rainfall through stronger evapotranspiration and moisture recycling. These findings indicate elevated flood risk during peak stages in urbanized coastal basins and support stage-specific flood risk management in eastern Zhejiang. • High-resolution WRF reveals stage-dependent and spatially varying urbanization effects on Typhoon Lekima rainfall. • Urban heat island and surface roughness jointly intensify convection and cumulative rainfall during typhoon peak periods. • Energy budget analysis clarifies the thermodynamic–dynamic pathways by which urbanization modulates typhoon rainfall extremes.