Comparative Analysis of the Effects of Typhoon Yagi (202411) and Typhoon Rammasun (201409) on Precipitation in Southeastern Yunnan

This study uses multi-source observational information—such as data from automatic station observation, final operational global analysis, advanced weather radar, and the China Meteorological Administration Meteorological Information Processing System—to analyze the varying effects of westward-moving typhoons Yagi and Rammasun on precipitation in southeastern Yunnan. The study aimed to provide a reliable scientific foundation for typhoon forecasting, warnings, and disaster risk assessments. The results showed that early movement paths, landing points, and intensities of both typhoons were remarkably similar. However, later in their trajectories, differences emerged due to the varying positions of the subtropical high and other physical factors, resulting in significant deviations in paths and intensities. The rainfall associated with the southern peripheral cloud system of Typhoon Yagi was more intense, with both daily and cumulative precipitation exceeding historical extremes. In addition, both precipitation events were sustained by tropical depressions in the Bay of Bengal, with continuous water vapor transport from both the Bay of Bengal and the South China Sea. Notably, no significant short-term heavy rainfall events or strong convective weather, such as strong winds, were observed during either typhoon event. In the later stages, Typhoon Yagi exhibited greater intensity, followed a more southerly path, and moved more slowly than Typhoon Rammasun. The convergence of wind and air fluxes, the distribution of pseudo-phase equivalent temperature (θ_se), and the distribution of high values of vertical upward motion were similar for both typhoons. However, Typhoon Yagi had a stronger intensity and longer duration, leading to a prolonged and more intense rainfall period from its residual vortex compared to that of Typhoon Rammasun.