Rainstorm events and driving factors in Pearl River Delta

Pearl River Delta is socioeconomically highly developed．Flash floods and urban inundation are mainly attributed to rainstorms．It is of great significance to investigate causes and driving factors behind such rainstorms．Most previous studies were done focusing on singular factors．In this study, precipitation indices were defined, potential driving factors of rainstorm events were identified, from CMORPH precipitation data, ERA5 meteorological data, ESA land use data and tropical cyclone disaster data．The driving factors of rainstorm events over Pearl River Delta were identified by correlation analysis, M-K test, synthetic analysis and Student’s t-test．Trends in rainstorm events were found not statistically significant on varied time scales．Net water vapor flux, air pressure and frequency of tropical cyclones were identified to be important variables behind changes in rainstorm events．Location and intensity of western Pacific subtropical high in summer was found to affect occurrence of rainstorm events．Urbanization and El Nino/La Nina phenomenon had no influence on rainstorm events．Rainstorm events tended to decrease surface temperature, attributing to increased cloud coverage．Our work provides some theoretical support and decision-making basis for predicting occurrence of rainstorm events, and for human mitigation of rainstorm-related disasters．