【摘要】 利用石家庄多普勒天气雷达资料和常规探测资料,对2008年5月17日发生在河北南部的强烈雹暴的生成环境和动力机制以及发展演变特征进行了分析。内蒙古东部冷涡后部的冷空气和低层暖湿气流在河北中南部交汇,导致这个地区上空的层结不稳定,低层的暖切变和地面的东风辐合线为触发系统。高低空急流、不稳定层结、强垂直风切变为强烈雹暴的发生提供了有利的环境条件。强烈雹暴的多普勒天气雷达观测特征表现为一个次超级单体的发展移动过程,呈现回波悬垂和弱回波区特征,强回波核区反射率因子达到73 dBz,三体散射现象明显,对应径向速度图表现为弱中气旋,旋转速度为15 m/s。次超级单体右移特征明显,沿承载层平均风方向偏右侧移动。风暴相对螺旋度(Srh)大值与强雹暴的产生密切相关,0.3～2.1 km的Srh正值出现以及2.1～6.1 km的Srh减小随后迅速增加对冰雹的预报有很好的指示意义。更多还原

【Abstract】 By using Shijiazhuang Doppler weather radar data and routine observation data of an intensive hailstorm on May 17,2008 in south of Hebei,analysis of its environmental conditions,dynamical mechanism and evolution characteristics were made.It was the cold air behind east-Mongolia cold eddy confluenced by moist-warm flow in low layer that the atmospheric stratification became instable.The trigger systems were low layer warm sheer and surface convergence line.Upper-low jet stream,instable stratification and strong vertical wind sheer were favourable environmental conditions.Typical hook echo,echo overhang and weak echo region(WER)appeared.The maximum reflectivity value was 73 dBz.Three-body scattering phenomenon was obvious.Radial velocity maps show a weak mesocyclone with its velocity 15 m/s.Sub-supercell storm shifted to the right side of average bearing layer wind direction.The big value of storm relative helicity(Srh) was closely related to the strong hailstorm.The positive Srh between 0.3 to 2.1km and Srh between 2.1 to 6.1 km firstly increased and then decreased quickly,which is the indications for the hailstorm forecast.更多还原