黔东南一次大范围弱冰雹天气过程分析

Analysis of a Wide Range of Weak Hail Weather Process in Qiandongnan

利用黔东南州气象资料、三穗C波段多普勒天气雷达资料及FNL再分析资料对2016年4月3日发生在贵州省黔东南州的一次大范围弱冰雹天气过程进行诊断分析。结果表明:此次冰雹过程环流形势是典型的"前倾槽"结构,辐合线和冷锋共同触发了不稳定能量的释放,降雹前地面气温较高,冰雹在下降过程中融化较快,使黔东南州大范围性降弱雹;对流发生前垂直风切变较大,SI、K指数满足强雷暴条件,0℃层和-20℃层高度适宜,但CAPE值能量有限,不利于大冰雹的形成;对流发生时低空维持高湿状态,切变线两侧风速风向的辐合为对流的发生提供了充足的动力条件;雷达资料显示冰雹发生时,在0℃等温线高度上有50 d Bz以上的反射率因子结构,低层辐合、高层辐散,风随高度的变化是中低层顺转,高层逆转,这种上冷下暖的结构有助于空气层结的不稳定,利于对流的发生。

The reanalysis data in a wide range of Guizhou Prefecture of Qiandongnan Province, the Weak Hail Weather Process on April 3,2016 was analyzed using Qiandongnan meteorological data, Sansui C band Doppler weather radar data and FNL. The results show that the hail circulation process is a typical ＂forward＂ structure, strong stratification instability, convergence line and cold from to trigger the release of unstable energy; the occur- rence of hail in Qiandongnan over the large vertical wind shear,low maintenance and high humidity; in the convec- tion occurs, SI index, K index well,0 ℃ layer and -20 layer height is appropriate ,convergence in the low -level shear line on both sides of the wind provides dynamic conditions sufficient for convection ; the radar data showed the hail occurs at 0℃ isotherm height above 50dBZ reflection factor structure, the radial velocity is low level conver- gence and upper level divergence, the wind change with height is lower clockwise, top reversal, the cold and warm air layer structure contributes to the instability in favor of convection.