2009年6月6日鄂北冰雹天气过程分析

利用常规观测资料和NCEP/NCAR再分析资料等，对2009年6月6日鄂北冰雹天气发生前的抬升、水汽及不稳定条件进行了诊断分析。结果表明：地面中尺度辐合线为冰雹天气发生提供了抬升条件，促进强对流天气爆发；垂直水汽分布上，中低层干盖的形成有效地抑制了边界层对流的发展，为不稳定能量的积聚创造了有利条件；地面“干线”的形成，增加了大气的潜在斜压性，促进了次级环流的发展，增加了大气不稳定性。多普勒天气雷达资料以及闪电定位等监测数据分析表明：雷达回波组合反射率强度、回波顶高和垂直液态水含量的迅速跃增，对降雹有较好的指示意义；10 min闪电频次在降雹前出现了20次以上的峰值，可以起到冰雹预警作用。

Analysis of a hail weather process in the northern Hubei province on June 6,2009

Based on the conventionally observational data and the NCEP/NCAR reanalysis data,a hail weather process on June 6,2009 in the northern Hubei province was analyzed,and the lifting trigger,water vapor and unstable conditions before this process were diagnosed.The results indicated that the surface meso-scale convergence line is the uplifting conditions of this hail process,which leads to the severe convective weather.A dry layer in the middle and low level effectively inhibits the development of convection in the boundary layer and creates favorable conditions for the accumulation of unstable energy.The formation of surface dry line increases potential atmospheric baroclinicity and promotes the development of the secondary circulation,thus atmospheric instability is increased.The analysis based on Doppler weather radar and lightning location data shows that reflectivity intensity of radar echo,echo top heights and vertical integrated liquid water(VIL) increase rapidly,and it is indicative to hail weather.Moreover,the peak values of lightning frequency during 10 min are important to hail warning if they appear more than 20 times ahead of hail occurrence.