【摘要】 通过对闪电VHF辐射源高时空分辨率的三维观测资料的分析发现,无论云闪还是地闪其时间和空间分布特征可表明雷暴中的基本电荷结构。云内闪电放电不仅发生在上部正电荷区与中部主负电荷区之间,也同样会在中部主负电荷区与下部正电荷区之间发生,除极性相反之外,其它特征是一致的。云闪过程在最初的10～20ms内垂直向上(正常极性)或向下(反极性)发展,之后转为水平方向的传输。在正电荷区辐射点较多,闪电通道清晰;在负电荷区辐射点较少,且从闪电的起始位置以一种倒退的方式水平延伸闪电通道。云闪中的K型击穿不仅发生在闪电的后期,而且还发生在活跃期,并不时发展到正电荷区而触发新的闪电分叉。负地闪首次回击之前的梯级先导过程辐射较强,继后回击前的直窜先导的辐射较弱。回击之间闪电在云内水平发展,通道以细小的分叉为主要特征,其间不时有没有到地的企图先导过程发生。正地闪的先导过程基本没有可探测到的辐射点,在回击之前有一段云内过程,回击之后有更长的云内过程发展,其闪电通道不像负地闪那样精细,在回击之后的最初阶段辐射点较少,而在通道的顶端辐射点反而较多。正负地闪的发生发展特征有很大的不同,表明正、负极性的电荷击穿及传输过程的机制存在明显差异。更多还原

【Abstract】 Thethree\|dimensional spatial and temporal development of impulsive VHF radiation eventsduring lightning discharges have been analyzed based on thedata measured by lightning mapping array (LMA) system with high spaceand time resolution. The resultsindicate that intracloud discharges(IC) and cloud\|to\|ground discharge (CG) can reveal the basic charge structure of thunderstorm. The intracloud dischargesoccured not only between the upper positive andlowernegative charge region, but also between lower positive and uppernegative charge region. Their characteristics were similar except for the opposite polarity. The channels of IC lightning propagated upward for normal and downward for invert during initial stage with 10～20 ms in time. After that, the channel changed to propagate horizontally in positive charge region. There were much more radiation points in positive charge region and lightning channel which clear. While there were less radiation points and lightning channels were extended from the starting point of lightning in a retrograde manner horizontally in negative charge region. \%K\% type breakdown appeared not only in last stage of IC lightning, but also in active stage and developed into positive charge region. The \%K\% type breakdown sometime triggered new channels in positive charge region. The negative step leaders produced intense radiation and dart leaders produced weak radiation for negative CG. The channels of negative CG lightning developed horizontally and produced a lot of small branches between return strokes. Some attempt leaders occurred during this period. The positive leaders produced no radiation. There were the development processes with long lasting time in cloud before and after positive return stroke. The characteristics of positive CG lightning were differed from that of negative CG lightning. This revealed that there were different breakdown mechanismsbetween positive and negative CG lightning.更多还原