空中人工引雷先导特征的统计分析  

Stastistic Analyses on the Leader Characteristics in Altitude Triggered Lightning Discharges

作　　者：张其林[1] 郄秀书[1] 王才伟[1] 肖庆复[1] 

机构地区：[1]中国科学院 寒区旱区环境与工程研究所,甘肃兰州730000

出　　处：《高原气象》2002年第2期167-174,共8页Plateau Meteorology

基　　金：中科院重大项目(KZ951-B1-405);国家自然科学基金项目(49975003)的共同资助

摘　　要：根据１９９８年８月２２日在广州从化５次空中引发雷电远近两个观测点得到的地面电场变化资料，　对主放电之前的先导传输特征进行了统计分析。结果表明：　双向先导系统稳定传输阶段，　近区电场为较慢的正极性电场变化上叠加负极性振荡脉冲；　远区的辐射场开始为双极性脉冲，　逐渐过渡到单极性脉冲，　而且双极性脉冲的初始极性与单极性脉冲极性以及小回击极性相同都为正。双极性脉冲幅度逐渐减小，　且初始半周期较光滑，　未观测到更高频小脉冲的叠加现象。双极性脉冲整个宽度为３．８　μｓ，　方差为０．３３　μｓ；　峰与峰间隔为１５　μｓ，　方差为２．４　μｓ　。单极性脉冲具有上升快而大的初始峰值、　慢而小的负反冲特性，　且初始上升部分较光滑，　未观测到高频小脉冲，　其上升时间为０．２３　μｓ，　方差为０．０５　μｓ；　半峰值宽度为０．３７　μｓ，　方差为０．１　μｓ；　脉冲间隔为１２　μｓ，　方差为３．４　μｓ　。单极性脉冲峰值逐渐增大，　就５次触发闪电而言，　最大先导脉冲幅度与小回击之比为０．２４，　范围在０．２～０．３之间。小回击后，　远区的单极性脉冲幅度小，　上升慢而下降快、　无明显负反冲，　平均间隔为２０．１　μｓ，　方差为６．１?Based on electric field change of five triggered lightning discharges at both far and near distances away from the site on August 22 1998 in Conghua, Guangdong Province, the leader propagation characteristics before main discharge were analyzed statistically. The results indicated that electric field variation at near distance was characterized by negative discontinuous oscillating pulses superimposed on slow positive change during the stable propagation regime of bi－directional leader system. Meanwhile, the radiation electric field at far distance began with bipolar pulses followed by unipolar pulses. The initial polarity of unipolar pulses and bipolar pulses was positive which was the same as that of the following mini－return stroke. The amplitude of bipolar pulses decreased slowly and no high－ferquency small pulses superimposed on the initial rise portion. The full width of bipolar pulses was 3.8 μs with a standard deviation of 0.33 μs. The time interval from peak to peak was 15 μs with a standard derivation deviation of 2.4 μs. The unipolar pulses were characterized by a large initial peak with a small and slow overshoot, and the initial portion was smooth without high－frequency mini－pulses. The rise time of unipolar pulses from zero to peak was 0.23 μs with a standard deviation of 0.05 μs. The time interval and standard deviation was 12 μs and 3.4 μs, respectively. After the mini－return strokes, the unipolar pulses occurred at regular time interval of 20.1 μs. After comparison with leader features in natural cloud－to－ground lightning discharges, it is found that the leader in triggered lightning discharges was consistent with that in natural lightning discharges.

关 键 词：人工引雷 空中触发闪 电场变化 双向先导 统计分析 

分 类 号：P483[天文地球—大气科学及气象学] P427.3