2006—2011年广州人工触发闪电观测试验和应用

Comprehensive Observation Experiments and Application Study of Artificially Triggered Lightning During 2006—2011

2006—2011年夏季在广州野外雷电试验基地开展了广东综合闪电观测试验(GCOELD)。试验期间,针对人工触发闪电进行了近距离声、光、电、磁特征等综合测量,对自动气象站电源线和信号线上产生的感应电压特征进行了观测和分析,并对广东省地闪定位网的探测效率和定位精度与人工触发闪电进行了比对和校验。试验结果表明:人工触发闪电回击峰值电流范围为-31.93～-6.67 kA,回击电流波形的半峰宽度的范围为6.18～74.19μs,10%—90%的上升时间范围为0.24～2.25μs。触发闪电的上行正先导的发展速度在10~4～10~5m/s量级;人工触发闪电的回击过程在架空电源线路(1200 m长,2 m高)上产生的感应过电压可达十几千伏;广东电网闪电定位系统对人工触发闪电事件的探测效率为95%,平均定位误差为759 m,闪电定位系统反演得到的电流峰值与实际测量的电流峰值平均相对偏差为16.3%。

The Guangdong Comprehensive Observation Experiment on Lightning Discharge （GCOELD） has been conducted in Guangzhou Field Experiment Site for Lightning Research and Testing, Conghua, Guang- dong, China from 2006 to 2010. In the experiments, the acoustics, optics, electricity and magneticele-ments of the discharge process in triggered lightning are observed synthetically. The characteristics of in- duced voltages produced by triggered lightning on power lines and signal lines of an automatic weather sta- tion are measured and analyzed. The triggered lightning technique is also used to test the detection effi- ciency and precision of lightning location system in Guangdong Province. The peak current of return stoke （RS） ,the transferred charge within 1 ms after the RS beginning, the half-peak width and the 10 ^--90 risetime for RS waveform are recorded and analyzed. The relationship between the luminosity of the light- ning channel and the continuous current intensity during the initial stage and interval of the return strokes for triggered lightning flashes is analyzed. The results reveal that, on the whole, luminosity of the air-ion- ized part of lightning channel shows obvious positive correlation with current. Linear correlation exists be- tween square root of integrated luminosity and current when the luminosity of lightning channel doesn＇t reach saturation in the high-speed images. However, the parameters in the fitting equation are slightly dis- tinct for different processes. The 2D propagation speed of upward positive leader for the triggered light- ning is about 104--105 m ~ s 1. The speed of downward negative teader involved in altitude triggered lightning is about 105 m ~ s 1. The information on the shape and velocity of the leader channel provided by the high-speed camera records and the synchronous electrical field change data are used to calculate the charge densities and current of upward positive leader for the triggered lightning. The results indicate that, prior to disintegration of the wire,the charge densities of the upward positive leaders range from sev eral micro-coulombs to hundreds of micro-coulombs per meter, and the distribution of charge densityis strongly skewed toward the upward positive leader tips. The calculated current in the upward positive lead- ers ranges from less than one to dozens of amperes, and increases with the ongoing propagation of the lead er. The induced voltage pulse caused by the RS on the overhead power line appears as a positive peak ini- tially and then declines sharply, followed by a negative peak, with a period of several microseconds be- tween the positive and negative peaks. The maximum negative and positive peaks of the bipolar induced voltages on the power line are --10.31 kV and 4.47 kV, respectively. The voltage associated with the fast-changing pulses superposed on the continuous current following the return strokes can exceed 1 kV. The waveform of voltage on the signal for wind speed shows the peak pulses resembled a ＂V＂ shape. The results of the lightning location system in Guangdong report that the flash and stroke detection efficiency are 92% and 450//00 for rocket-triggered lightning, respectively. The space location error ranges from 111 to 5250 m with a mean space location error of 759 m. The relative error between peak current estimated by LLS and the direct measured current from the channel bottom of artificial triggered lightning is 16.3~.