Analysis on the Hail Climate and Radar Characteristics in Linyi City

[Objective] The research aimed to study the hail climate and radar characteristics in Linyi City.[Method] The five representative stations which were Mengyin,Yishui,Linshu,Cangshan,Linyi and were collectively called as Linyi City in Yimeng mountain area were selected.From the hail path,weather situation and influence system,the 40 times hail weather processes which happened in every station in June during 1965-2008 were carried out the statistics analysis.The typical weather situation and physical structure characteristics in the hail weather process in Linyi City were studied.On this basis,the statistical analysis on the new generation weather radar characteristics in the hail process during 2003-2008 was carried out.The climatic index of hail occurrence,the characteristic index of radar data and the radar observation characteristic in the city were discussed.[Result] The weather systems which affected the hail shooting in Linyi City were Mongolia cold vortex type,eastward shift small trough type,northwest airflow cold temperature trough type and so on.On the 6 h ground chart before the hail shooting,there were the small low pressure,cold front or wind shear line(airflow convergence field) in Shandong Province.They had the trigger and effects on the occurrence and development of strong convection hail shooting.The joining of small trough in the rear of 500 hPa low vortex had three forms that were the west small trough supplementary type,the airflow field divergence in front of vortex and the small trough in the rear of vortex southward swing in general.When the vertical liquid water content quickly increased from zero or the small amount to above 40 kg/m2,it was possible to generate the hail weather.In the different months,when the echo intensity of convective cloud body 50 dBz,the initial echo height 5 km,and the crown elevation,strong center height reached the certain values,it was possible to generate the hail weather.On the radar radial velocity chart,the meso-scale convective system characteristic(the bottom layer was the convergence,and the high layer was the divergence) was obvious.At 1.5° and 3.4° elevation angles in the middle layer,there was the strong wind shear in the vertical direction of convective storm monomer.[Conclusion] The research provided the certain reference value for the analysis and forecast of this kind of weather.