中文摘要：

利用时间分辨率为0．1μs的快天线电场变化和126MHz（带宽6MHz）甚高频（VHF）辐射资料，对甘肃平凉地区雷暴过程中闪电辐射特征进行了分析研究；并引入脉冲丰度这一概念，对地闪各特征阶段VHF辐射脉冲进行定量分析。统计分析发现：在地闪首次回击前，各特征阶段脉冲丰度有明显不同，回击过程脉冲丰度最高，并且其VHF辐射脉冲幅值远大于其余阶段；而在回击之后，有时仍存在很强的VHF辐射，其辐射脉冲幅值甚至超过了回击过程和梯级先导过程；云闪的初始阶段VHF辐射会有间歇性变化，其脉冲序列持续时间一般很短，活跃阶段VHF辐射脉冲较丰富，云闪末尾阶段VHF辐射脉冲稀少。最后对这些现象进行了理论探讨，认为地闪各特征阶段脉冲丰度的明显不同，是地闪各阶段放电强度以及放电机制的不同造成的。

英文摘要：

The very high frequency（VHF） radiation characteristics of cloud-to-ground（CG） lightning in Pingliang area of Gansu province were analyzed by using the data from a fast antenna system with a time resolution of 0.1μs and a VHF radiation receiver with a central frequency of 126 MHz and a bandwidth of 6 MHz. A concept of pulse plentiful degree（PPD） was introduced to interpret quantitatively the VHF radiation phenomena in each discharge stage of lightning. The result indicates that the PPD is very different in different characteristic discharge stage. Both the PPD and the intensity of VHF pulse in the first return stroke stage are larger than that in other stages. VHF radiation occurred occasionally after the return stroke in some of the CG lightning events, and the intensity is equal or even exceeds that in the return stroke stage and the stepped leader stage. The VHF radiation pulse is discontinuous, and the duration of pulse sequence is very short in the beginning of intracloud lightning discharge. The PPD is large in its active stage, and few in its dissipation stage. In addition, the phenomena was discussed theoretically, and it was found that the difference of PPD in different stage of the CG lightning discharge is caused by the difference of discharge intensity and discharge mechanism.