Analysis on the Abnormal Distribution of Large-scale Rainstorm in Guangxi Caused by typhoon Bailu (1911)

Abstract Typhoon "Bailu" of 1911 caused extensive rainstorms in Guangxi,and its rain intensity and distribution were abnormal. The rainstorm was mainly concentrated in the east and south, and the rainstorm belt was northeast-southwest. Many forecast products, including subjective and objective forecasts, showed deviations in the area and intensity of this rainstorm. The weather dynamic diagnosis and analysis method was used here to analyze the causes of the abnormal distribution of the rainstorm based on conventional meteorological data and European centre reanalysis data, satellite cloud images, and mesoscale automatic stations. The results showed that this rainstorm caused by "Bailu" was formed by the coupling of low-and-upper level jets circulation and strong water vapor convergence. The guidance of the subtropical high airstream caused the clouds on the southwest side of the "Bailu" to move slowly westward. The input of the southwest monsoon airstream revived, strengthened and maintained the "Bailu" vortex. The plenishment of abundant water vapor caused continuous and concentrated rainstorm in the eastern and southern regions of Guangxi. The asymmetric structure of typhoons was also an important reason of abnormal precipitation distribution.