Research on Spatio-temporal Distribution of Hail and Radar Echo Warning Indicator in Zhangjiajie
Yi Wenjun
Zhou Wei
He Bingwen
Liang Ke
Zhou Yaqin
Lai Xiaodan
Abstract：This paper analyzes 70 hail cases in Zhangjiajie City in detail using conventional observa-tion data and weather radar data.The results show that the high mountains in the northwest of Zhangjiajie City and the canyon mountains in the north-central part are two hail shooting centers,where the annual average number of hail days is 1.06 d with an increasing trend.Spring is the high occurrence period of hail,especially in April,and the peak period of hail occurrence is from noon to evening,mostly from 17:00 to 18:00.The height of the characteristic layer WBZ favorable for hail formation is 3.6-4.3 km,and the-20℃layer is as high as 7.0-8.4 km.When the height difference ΔH between DBZ and WBZ reaches 0.4-0.7 km,it is conducive to the occurrence of severe hail.When the height of the reflectivity factor≥50 dBZ extends to the height above the-20℃isotherm,the presence of upper-level overhanging radar echo and the WER or BWER below it are important indicators of hail warning.Three-body scattering and sidelobe echo are important warning indicators of severe hail,and sidelobe echo is earlier than TBSS for the early warning of hail.The VIL threshold of severe hail is 42.5 kg/m2 and the VILD threshold is 4.0 g/m3.In addition,the velocity differential(ΔV)of≥37.5 m/s between the positive and negative val-ues of the storm-top divergence is also an warning indicator of severe hail.
Keywords：hailoverhanging echobounded weak echo zonethree-body scatteringVIL density
Publication Date：2025-01-30
Online Publishing Date：2026-09-12(First online date of this platform, not the publication date of the document)
Pages：9( 56-64 )