Abstract On 7 September 2023, a century‐record‐breaking precipitation occurred in the world's largest urban agglomeration. Notably, the precipitating system of Typhoon Haikui was significantly enhanced rapidly as it approached the metropolitan areas. This study investigates the underlying mechanisms and relative contributions of urban‐anthropogenic impacts on metropolitan precipitation using the three‐dimensional variational radar data assimilation and the Weather Research and Forecasting model. The results suggest that urban land use (URBAN), urban canopy (UC), anthropogenic sensible heat (ASH), anthropogenic latent heat (ALH), and building heights (BH) enhance precipitation by 40.6%, 18.0%, 17.5%, 12.7%, and 6.5%, respectively. Specifically, ASH and ALH increase temperature and humidity, enhancing the precipitation downstream of the urban core. In contrast, increased surface roughness associated with BH reduces wind speed, promotes low‐level convergence and modulates rainfall distribution upstream of the urban core. These findings highlight the critical role of megacities in shaping extreme typhoon‐induced precipitation, and underscore the importance of accurately representating UC processes in numerical simulations.
Shan et al. (2026) studied this question.