Abstract:By the conventional meteorological observation data, ERA5 hourly reanalysis data, and other sources, a comprehensive analysis was conducted on an extreme rainfall event that occurred in northern Guangdong from June 22 to June 24, 2023. This analysis focused on the circulation background field, dynamic causes, water vapor environment, and moisture transportation characteristics associated with the heavy rain. The results indicated that the 500 hPa upper-level trough, 850 hPa low vortex shear, and anomalously strong southwest monsoon were the direct influencing systems for this precipitation event. The divergence in the upper atmosphere and strong upward motion facilitated the upward transport of water vapor in the rain-affected area. The southwestern water vapor channel was established early, and the later addition of water vapor from the South China Sea provided a continuous supply of moisture for the sustained extreme heavy precipitation. The trajectory clustering analysis conducted 120 hours later revealed that the moisture transport paths below 500 hPa are relatively similar across various layers, primarily comprising three channels: the eastern Pacific, the southern South China Sea, and the western Indian Ocean-Bay of Bengal. Among these, the moisture originating from the eastern Pacific contributes the most.Throughout the heavy rain event, the southern and western boundaries at the lower levels exhibited net inflow, whereas the eastern and northern boundaries demonstrated net outflow. Notably, during both the peak and the weakening periods of the heavy rain, the moisture inflow from the southern boundary was at its highest.
