滇中地区冰雹的多普勒天气雷达及闪电活动特征分析

Characteristics Analysis of Doppler Radar Echoes and Lightning of Hailstorms in Central Yunnan Province

利用雷达数据和云南省闪电定位系统数据,对滇中地区2006~2011年6次典型降雹过程中的雷达回波和闪电特征进行综合分析,结果表明:滇中冰雹回波的基本反射率因子具有典型的冰雹回波特征,如弓形回波、三体散射、旁瓣回波、有界(无界)弱回波区、"V"型槽口以及钩状回波等。地面降雹区基本出现在雹暴反射率因子强度梯度较大的区域,也就是负地闪密集活跃区或者临近区域。闪电密集区的移动可作为预测冰雹回波移动路径的一个指标。降雹时段是负地闪的活跃期,正地闪出现频率极少,这与我国北方地区冰雹出现时高正地闪频数特征存在明显不同。负地闪每5 min频数峰值的出现时间略超前地面降雹时间5~12 min,可作为滇中出现冰雹的一个参考指标。闪电频数的时空分布和变化特征,对于滇中地区冰雹天气的监测、I临近预警以及防雹作业指挥有一定的参考作用。

Using the data collected from Doppler radar and lightning detection network in Yunnan Province,the characteristics of radar echo and cloud-to-ground(CG) lightning in six typical hail processes are analyzed comprehensively in Central Yunnan Province from 2006 to 2011.The results show that there are typical characteristics of hailstone echoes in basic reflectivity radar images,such as bow echo,TBSS,side lobe echo,WBER(BER),V-shaped notch,hook echo,etc.Hail area always appears in the places where basic reflectivity gradients are high,and the negative CG lightnings are dense and active as well.The movement of the concentrated CG lightning area can be the index indicating the moving of hailstone echoes.The hailing periods are the active phase of negative CG lightning,during which the appearance of positive CG lightning is seldom seen.This is significantly different from the hailing with the high positive CG lightning frequency feature in northern area of China.The peaks of 5 min negative CG lightning occur 5-12 min earlier than hailstone falling,which can be regarded as a reference index of predicting hailing in central Yunnan Province.The spatio-temporal distribution and changing of negative CG lightning frequency could play some reference roles in monitoring and warning hails and commanding hail operations in Central Yunnan Province.