中文摘要：

利用2009年山东人工触发闪电实验获取的实测雷电流资料、近距离电场和高速摄像资料，分析了6次峰值电流达几千安量级的M分量．6次M分量均对应闪电通道中明显的发光亮度的脉冲式变化，持续时间小于1ms．M分量的电流波形和近距离电场波形均呈较为对称的V形，且波形的上升时间均为几十微秒，同步记录结果显示，电场先于通道底部电流发生变化且先达到峰值．这些肘分量在发生前，闪电通道中存在一定的连续电流，通道的导电性优于先导一回击过程．肘分量发生前的闪电通道状况是影响其电流幅值、上升时间等参数的重要因素．根据电流和电场同步波形判断，M分量起始于由上向下发展的过程，该过程在接地后仍继续发展增强，并在地面发生反射过程，下行过程和反射过程的相互作用可能随高度而变化．

英文摘要：

Characteristics of six M-components with peak currents of kilo amperes are analyzed by using the data from the artificially triggering lightning experiment in Shandong 2009, including the current at the base of the discharge channel, the surface electric field change at 30 m from the channel, and the high-speed camera records. The M-component is associated with the abrupt enhancement of channel luminosity with a duration of less than l ms. Both the current and electric field are characteristic of relatively symmetric waveforms with a rise time of several tens of microseconds. The simultaneous records show that the electric field starts to change and reaches its peak earlier than the channel base current. Because of the obvious continuing current flowing in the channel, the conductivity of the discharge channel prior to the M-component is better than that prior to the leader-return strokes. The channel condition before the occurrence of the M-component is crucial to current amplitude and rise time. According to the waveforms of current and electric field recorded simultaneously, it is inferred that the M-component evolves from up to down and the evolvement continues after contacting the ground, and then an upward reflected process is induced. Further analysis shows that the interaction between these two processes is likely to be changed with altitude.