皖北两次龙卷过程对比分析

利用常规资料、NCEP再分析资料、高密度地面自动站资料、多普勒天气雷达资料，对安徽省灵璧县和泗县发生的两次龙卷过程进行对比分析。结果表明：龙卷风发生在低空急流的北端左侧以及高湿中心和水汽辐合中心的交汇处；龙卷风发生前低层垂直风切变强烈；龙卷风发生在地面辐合最强的地方，为判断龙卷风可能发生的区域提供了线索；龙卷风发生前10～20 min均有龙卷涡旋特征报警，同时有中等强度中气旋配合；灵璧龙卷风出现在母体风暴的南端，强回波在3 km以下；泗县龙卷风发生在带状回波的中部，中气旋由弱发展为中等强度后一个体扫龙卷出现，龙卷风发生时强回波有断裂和突前以及中气旋顶高下降的特征。

Comparative Analysis of Two Tornado Events over Northern Anhui Province

An analysis is made of two tornado events in Lingbi and Sixian counties,Anhui Province,by means of the conventional data,NCEP data,intensive observations,and Doppler radar data.The results show： the tornadoes occurred on the left of the low level jet at the intersection point of high-humidity center and vapor convergence center;before tornadoes appeared,the low level vertical wind shear was strong;the tornadoes occurred in the areas where the ground convergence was the strongest;there were clear vortex features and a mid-level cyclone in 10 to 20 minutes before tornado occurred;the Lingbi tornado appeared in the south of the storm with strong radar echoes under 3 km;the Sixian tornado appeared at the center of the banded radar echoes with strong splited and protruded echoes,and the mesocyclone top descended.