Electric field characteristics of leader and return in triggered lightning

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 ap