2024年"4·27"广州致灾超级单体强龙卷风过程研究OA

Based on new-type observational data from dual-polarization radars with different bands and wind profile radars in Guangzhou,this study investigates the environmental conditions and storm structural characteristics of the deadly supercell tornado that occurred in Baiyun District,Guangzhou,on April 27,2024.This tornado event deveoped under a persistently strong southwesterly wind on the southern side of the Tibetan Plateau and the influence of the Western Pacific Subtropical High.The atmospheric stratification profile exhibited a"trumpet-shaped"profile,characterized by dry upper levels and moist lower levels.The lifted condensation level(LCL)was remarkably low in the morning(approximately 180 m),accompanied by abundant energy(Convective Available Potential Energy(CAPE)of approximately 2500 J·kg-1 and Convective Inhibition(CIN)of 0 J·kg-1).Additionally,strong 0-3 km wind shear(17 m·s-1)further indicated favorable thermodynamic and dynamic conditions for the development of a severe tornado.The parent supercell responsible for the tornado exhibited a long lifecycle and underwent multiple intensification periods.The tornado occurred during a relatively quiescent period between two intensity peaks,posing significant challenges for forecasting and early warning.The parent storm displayed distinct hook echo and mesocyclone characteristics,with a"descending-type"developmental pattern.Due to minimal influence from surface friction,the storm developed more vigorously.The downdraft of the parent storm formed a cold pool,with the strongest center temperature dropping to 22℃and a radius of approximately 30 km.A gust front at the leading edge of this cold pool enhanced low-level convergence and uplift,intensifying the mesocyclone as it approached the ground.Prior to the tornado,the vertical vorticity of the mesocyclone was 0.026 s-1,while the vertical vorticity of the Tornado Vortex Signature(TVS)reached 0.46 s-1.Furthermore,compared to the CINRAD/SA-D,the XPAR-D captured clearer tornado signatures,such as the TVS and the Tornado Debris Signature(TDS),as well as more detailed evolution of the low-elevation hook echo.In operational applications,these radars demonstrate complementary advantages,enabling more precise characterization of the development of local severe convective storms and providing crucial technical support for nowcasting and early warning.