人工引发雷电先导-回击过程的电场变化特征

Electric field characteristics of leader and return in triggered lightning

2005年夏季在山东滨州进行了以人工引发雷电为主的综合观测实验，在负电场环境下，成功引发雷电5次，其中传统引发方式3次，空中引发方式2次。详细分析了双向先导-小回击过程和箭式先导-回击过程的垂直电场变化特征。结果表明：2次空中引发雷电的双向先导发展过程在地面60m处产生的电场变化为4．70～14．60kV／m，呈负向变化;在550m处为0．11-0.16kV／m，呈正向变化。利用60m处的先导电场变化，估算双向先导电荷线密度分布的斜率为（1．2～3．8）×10^-7C·m^-2。箭式先导-回击电场变化波形呈不对称V形，V形的底部对应先导的结束和回击的开始。60和550m处的箭式先导电场几何平均值分别为17．80和1．20kV·m^-1。随水平距离的增加，箭式先导电场以水平距离的-1．18次方衰减。

In the summer of 2005, a comprehensive observation on triggered lightning discharges was conducted in Binzhou, Shandong. Five lightning flashes were successfully triggered with three with classical triggering method and two with altitude triggering method. The vertical electric field changes of the bidirection leader system and the dart leader-return stroke of negative triggered lightning discharges at distances of 60 m and 550 m are presented. The electric field changes produced by the bidirection leader system at 60 m and 550 m are negative 4.70-14.60 kV/m and positive 0.11-0.16 kV/m, respectively. The slope coefficient of the charge distribution along lightning channel for the bidirection leader system is estimated to be （1.2-3.8） × 10^-7C·m^-2. The dart leader-return stroke sequences appear as V-shaped pulses, with the bottom of the V-shaped pulse being associated with the transition from the leader to the return stroke. The electric field changes produced by the dart leaders at 60 m and 550 m are 17.80 kV/m and 1.20 kV/m respectively. The distance dependence of the dart leader electric fields change is the - 1.18th power of the horizontal distance.