An elevated thunderstorm hail event occurred in Chenzhou and its vicinity in the Nanling region during March 22-23,2023.A wide range of hail with diameters reaching up to 20 mm was reported,which was rare in elevated convection.In order to enhance the capabili-ty of forecasting and early warning of such hail events,this paper uses conventional meteorological observation data and SA-band dual-polar-ization radar products to analyze its weather conditions and dual-polarization radar echo characteristics.The results are as follows.(1)This event occurred in the cold area on the north side of the surface front,which was a typical elevated thunderstorm process.The hail-falling ar-ea was located 140 km to the north side of the surface front,and the large hail of 20 mm in diameter was caused by a supercell storm.(2)The storms that caused large hail in southern Chenzhou can be divided into four stages,which are the initial stage,the rapid development stage,the hail-falling stage,and the weakening stage.During the rapid development stage,the strong echo center increases rapidly and the vertical cumulative liquid water content(VIL)increases sharply.The differential reflectivity(ZDR)column extends to 4～5km above the 0 ℃ layer.A stronger updraft provides favorable conditions for hail development.During the hail-falling stage,with the rapid decrease of the strong echo center,the weak echo region(WER)disappears,and the height of the ZDR column decreases significantly.The values of ZDR and specific dif-ferential phase(KDR)gradually increase as the melting hail falls toward the ground.While the footprints of KDR correspond well with the hail-falling region.(3)The three-body scattering(TBSS)characteristics of large hail showed that the ZDR value at the root was large,which then decreased rapidly with the increase of radial distance,and the cross-correlation coefficient(CC)was significantly low.The sidelobal echo features of large hail indicate a low ZDR and low CC signature.These dual polarization features are key concerns for the large hail warning.
维普
万方数据