Characteristics and Genesis of Shandong Rainstorm Caused by the Residual Vortex of Typhoon Chaba(2203)

Cao Yueyao; Cong Chunhua; Yu Tengfei; Yan Haifan; Ge Yao

doi:10.16765/j.cnki.1673-7148.2026.03.003

Abstract：This study analyzes the characteristics of a widespread rainstorm event in Shandong Prov-ince from July 5 to 6,2022,which was triggered by the interaction between the residual vortex of Ty-phoon Chaba(2203)and a westerly trough,utilizing the China Meteorological Administration Tropical Cyclone Best Track Dataset,conventional meteorological observations,Fengyun-4 satellite imagery,Doppler weather radar,wind profile radar data,and hourly ERA5 data.The results indicate that the main precipitation period exhibited strong integrated water vapor flux convergence at approximately 3×10-5 kg·m-2·s-1 and high specific humidity values of 14-16 g·kg-1 at 850 hPa,providing favorable moisture conditions for the heavy rainfall.Prior to the extratropical transition of the residual vortex,the western Pacific contributed 80%of the moisture,with 46.67%originating from the ocean southeast of Ja-pan;following the transition,the primary moisture source shifted to the southwest,dominated by the northern Indian Ocean,which illustrates the important role of water vapor transported by the strengthening and northward movement of the jet stream in the residual vortex maintenance and rainstorm generation.Atmospheric instability caused by low-level cold air intrusion was the primary factor contributing to the strong precipitation after the residual vortex transition.The level distribution of frontogenesis function and the wind direction transition showed by wind profile radar had a strong correlation with the invasion of low-level cold air and the significant increase of hourly rainfall intensity at observation stations.The wind profile radar data effectively compensated for the limitations of satellite water vapor imagery in detecting low-level cold air invasions.