Various Properties of Natural and Triggered Lightning Discharges

9726100 Rakov虽然闪电现象已经被观察了一段时间，但许多方面是未知的。本研究的总体目标是进一步完善雷电放电物理过程的现有知识。计划进行实验和理论研究。实验研究将在位于佛罗里达州布兰丁营地的国际闪电研究和测试中心以及位于盖恩斯维尔的佛罗里达大学校园的闪电天文台进行。布兰丁营地有独特的设施，可以从头顶的雷雨云中触发人工闪电。对于触发和自然闪电放电，将测量电场和磁场。通道基电流将额外测量触发闪电。闪电通道的光学图像将通过各种视频、静止和条纹相机以及数字光学系统获得。GPS授时将允许这些测量与国家闪电探测网络报告和舒曼共振瞬变的发生相关联。将尝试发起和描述更有能量和可能产生精灵的正闪电。将研究非接地物体引发闪电和闪电附着地面的详细机制。8个站点的电场和磁场测量，其中7个站点位于触发闪电通道的5到500米之间，将用于推断闪电通道上电荷密度和电流的分布，并验证或反驳现有的闪电模型。为了解决长期以来关于闪电能量大小的争论，将首次尝试对闪电能量进行实验研究。总的来说，拟议的研究结果将为各种照明过程的物理学提供新的见解，并对大气科学的其他领域产生影响，包括大气化学（闪电产生微量气体的能量）和闪电与高层大气的相互作用（特别是正闪电产生的精灵）。* * *

9726100 Rakov While the phenomenon of lightning has been observed for some time, many aspects are unknown. The overall objective of this research is further improvement in the existing knowledge of the physical processes comprising the lightning discharge. Both experimental and theoretical studies are planed. The experimental studies will be conducted at the International Center for Lightning Research and Testing at Camp Blanding, Florida, and at the Lightning Observatory on the University of Florida campus in Gainesville. Camp Blanding contains unique facilities for artificial lightning initiation (triggering) from overhead thunderclouds. For both triggered and natural lightning discharges, electric and magnetic fields will be measured. Channel-base currents will be additionally measured for triggered lightning. Optical images of lightning channels will be obtained with a variety of video, still, and streak cameras, and with a digital optical system. GPS timing will allow the correlation of these measurements with the National Lightning Detection Network reports and to the occurrence of Schumann resonance transients. Attempts to initiate and characterize more energetic and potentially sprite-producing positive lightning will be made. Detailed mechanisms of lightning initiation from an ungrounded object and of lightning attachment to ground will be studied. Measurements of electric and magnetic fields at eight stations, seven of them between 5 and 500 meters of the triggered-lightning channel, will be used to infer the distribution of charge density and current on the lightning channel and to validate or refute existing lightning models. The first attempt to study experimentally the lightning energy in order to resolve the long-standing controversy on its magnitude will be made. Overall, the results of the proposed research will provide new insights into the physics of various lighting processes with implications for other areas of Atmosp heric Sciences, including atmospheric chemistry (energy available for trace gas production by lightning) and the interaction of lightning with the upper atmosphere (in particular, the production of sprites by positive lightning). ***