中国内陆高原正极性雷电的观测实验研究

OBSERVATION OF POSITIVE LIGHTNING IN THE INLAND PLATEAU OF CHINA

叙述了１９９７年夏季中日两国科学家在甘肃平凉地区合作进行的有关正极性雷电的综合观测实验情况，包括场地布局、所采用的技术手段及取得的主要结果。实验中采用了人工引发雷电技术并取得了两次成功，其中一次是利用“空中触发”方式，即火箭拖带的细钢丝下端不直接接地，而是通过一段绝缘尼龙线与接地的另一段细钢丝相连。用这种方式可以更真实地再现自然雷电的初始过程。实验中观测到了空中导线两端先导的双向传输现象；电流、电场变化的同步测量以及高速摄像的光学测量揭示出下行正先导激发后在０．７ｍｓ内和上行迎面负先导会合。实验还表明，利用人工引发雷电技术，配合多种先进的仪器设备进行综合观测，不但有助于揭示中国内陆高原雷暴过程中正极性放电的机理和特征，而且也是今后雷电研究的有效途径。

In the summer of 1997, Chinese and Japanese scientists conducted jointly a comprehensive observation of positive lightning in Pingliang, Gansu province which is located in the east verge of Qinghai -Xizang Plateau. This paper presents the field experiment arrangement, measuring technique and main results obtained. During the experiment, the technique of artificial triggering lightning was used and two cases of triggered lightning were obtained. Among them the so-called ‘altitude triggering technique’ was used in one case, ie., the lower end of still wire pulled by ascending rocked was attached to the ground not directly but through a length of insulated nylon line. In this way the initial process of natural lightning could be reproduced more truly. A bi-directional leader process initiated from both ends of altitude wire was observed. Simultaneous measurement of current and field change as well as luminosity measurement by high speed video cammera revealed that after initiation the downward moving positive leader connected in the period of 0.7ms to the upward moving negative leader. The experiment shows that the comprehensive observation by using the technique of artificially triggered lightning and advanced instruments is conducive to revealing the characteristics of positive lightning in the inland plateau of China , and also an efficient way to study the mechanism of lightning discharge.