摘要
在广州野外雷电试验基地,对2008年和2011年夏季人工触发闪电回击之后的14个连续电流过程和43个M分量的通道底部电流、电场变化和通道亮度进行了同步测量和分析。结果表明:M分量的电流、快慢电场变化和亮度变化波形均近似对称;触发闪电连续电流过程的持续时间、转移电荷量、电流平均值的几何平均值分别为22 ms,6.0 C和273 A;M分量的幅度、转移电荷量、半峰值宽度、上升时间、持续时间的几何平均值分别为409 A,205 mC,520μs,305μs和1.6 ms;连续电流持续时间与M分量的个数、相邻M分量之间的时间间隔均存在显著的正相关关系。
The continuing current （CC） process of cloud-to-ground lightning is a discharge process in which charges continuously transfer to ground along the lightning channel after return stroke. The magnitude of CC is small, but the duration of CC is commonly long, so CC often causes lightning disaster. It＇s very hard to get current data due to the randomness of lightning. Artificially triggered lightning, in which the time and location of triggered lightning can be controlled, is an effective way to measure current of lightning. Artificially trigged lightning is different from nature lightning which only has CC after return stroke, yet artificially trigged lightning has CC and initial continuous current （ICC） process both. Only the CC is analyzed using simultaneous observations of current, electric field change and chnnel luminosity by coaxial shunt, fast and slow antenna, and high-speed camera in Guangzhou Field Experiment Site for Lightning Research and Testing, Conghua, Guangdong, China. Then, photoelectric character and characteristic parameters of 14 CC and 43 M-components after return strokes of triggered lightning observed in summer in 2008 and 2011 are analyzed. The relationship between some characteristic parameters of CC and M-component is analyzed, too. The current waveforms of CC after return strokes are continuous and change slowly. Usually, there are current pulses ranging in size superimposed on CC waveforms. The slow electric field waveforms of CC are slowly changing, too. The lightning channel below the cloud is always luminescent during CC. The current waveforms, fast and slow electric field waveforms and channel luminosity variation waveforms of M-components are approximate symmetrical. The geometric mean of duration, charge transferred to ground, average current and action integral for CC are 22 ms, 6.0 C, 273 A, 4187 A^2s, respectively. The geometric mean of magnitude, charge transferred, half peak width, rise time （10%-90%）, duration, preceding CC level, inter-pulse interval, action integral for M-components are 409 A, 205 mC, 520μs, 305μs, 1.6 ms, 310 A, 6.5 ms, 465 A2s, respectively. There are very remarkable positive correlations between the duration of continuing current and number of M-components, and between the duration of continuing current and inter-pulse interval of M-components. The correlation coefficients are 0.83 and 0.75, and both pass the significant verification of 0.01 level.
出处
《应用气象学报》
CSCD
北大核心
2014年第3期330-338,共9页
Journal of Applied Meteorological Science
基金
国家自然科学基金项目(41030960
41075003
41205002)
公益性行业(气象)科研专项(GYHY201006005)
中国气象科学研究院基本科研业务费专项(2010Z004)
海南省重点科技计划项目(ZDXM20120057)
关键词
人工触发闪电
连续电流过程
M分量
特征参数
artificially triggered lightning
continuing current
M-component
characteristic parameter
