Experiments of artificially triggered lightning and its application in Conghua, Guangdong, China

The Guangdong Comprehensive Observation Experiment on Lightning Discharge (GCOELD) was conducted from 2006 to 2011 in Conghua, Guangdong, China. In GCOELD, the acoustical, optical, electrical and magnetic signals of triggered lightning and natural lightning were measured. For the triggered lightning, the peak current of the return strokes (RSs) ranged from 6.67 to 31.93kA. The transferred charge within 1ms after the beginning of the RS ranged from 0.44 to 4.16 C. The peak currents showed different-function correlations with average rate of rise between 10 and 90%, maximum rate of rise, charge transfer and action integral. The 2D propagation speed of the upward positive leader for the triggered lightning was of the order of 104–105ms−1. The speed of the downward negative leader involved in altitude-triggered lightning was approximately 105ms−1. The characteristics of induced voltages produced by triggered lightning on a power line and signal line of an automatic weather station were measured and analyzed. The maximum induced voltage generated by the RS on the overhead power line (1200m in length and 2m above the ground) exceeded 10kV. The maximum induced voltage on a vertical 10-m signal line was 3.10kV. The triggered-lightning technique was also used to test the detection efficiency and location precision of the lightning location system (LLS) in Guangdong. It was explored that the Guangdong LLS yielded detection efficiency and location error of 92% and 760m, respectively, for triggered flashes. For RSs of the triggered lightning, the peak currents given by the LLS deviated from those measured at the base of the lightning channel by 16% on average.