“20110629”云南特大区域性冰雹天气过程分析

Analysis on an extra territorial hail event happened on June 29^(th), 2009 in Yunnan Province

综合利用1°×1°NECP再分析资料、MM5数值模拟资料、多普勒雷达资料和闪电资料,对2011年6月29日发生在云南的特大区域性冰雹天气过程进行动力诊断、雷达回波和地闪特征分析.研究结果表明:此次天气过程是西北气流携带冷平流与西移的热带低压外围高能高湿气流相互作用先后触发的一个中-γ尺度对流风暴和中-β尺度的飑线造成的.侵入的东北风与西北风发生碰撞、辐合促进了对流的发展;冰雹发生前中低层有对流不稳定能量的聚积,对流系统发展到成熟阶段时对流不稳定能量达到峰值;垂直风切变的加强使得高低层发生能量交换,激发对流不稳定能量的释放,促使强对流天气的爆发,垂直上升运动最大值的高度在冰雹临近时高于0℃层高度,利于冰雹天气的形成;冰雹发生前500 hPa有冷平流输送,存在"冷心"结构,冰雹临近时"冷心"高度有明显上升;风暴的整个生命史具有非常低的地闪频数;风暴在成熟期,正地闪有一个突然集中发生的阶段,正地闪的百分比明显增加,对应着地面强天气的发生.

1°×1° NECP reanalyzed data,MM5 numerical modeling data,Doppler Radar data and lighting data have been used to analyze the dynamic characteristic,radar echo and CG lighting features of an extra territorial hail event on June 29th,2009 in Yunnan Province.Research results indicate that γ meso scale convective storm and β meso scale squall line,which caused by the interaction of north-west cold advection and high-energy,high-humility air flow around tropical depression,initiated the hail event.Collision and convergence between invasive northeast wind and northwest wind promoted convective activity.The convective instable energy assembled before the hail,and reached peak value when the convective system developed to maturation period.The increasing of vertical wind shear speeded the energy exchanging on upper layer,then the instable energy was released,leading to the breaking out of severe convective weather.With the drawing near of the hail,height of the maximum value of vertical motion was lower than the height of 0 ℃ layer,and that phenomenon was beneficial to the formation of hail.There was cold advection transporting on the layer of 500 hPa before the hail,causing the formation of ＂cold core＂,and drawing near of the hail the height of ＂cold core＂ hoisted obviously.During the whole lifetime of storm,the frequency of CG lighting was very low.At the maturation stage of storm,there was a period in which positive CG lighting happened suddenly in an intensive way.Then the percentage of positive CG lighting increased obviously which was corresponding to the happening of severe weather.