摘要
基于高速摄像系统获取的自然闪电通道形状，利用分形方法构建了分形闪电通道模型，分析计算了闪电通道的弯曲对地面附近不同方位、不同距离处回击电磁场的影响。结果表明，在100m到10km的近距离范围，不同方位的回击垂直电场峰值之比为0．8～2．3；而当距离增加时，这种差别逐渐消失。但无论距离远近，地面水平磁场随方位角都存在较明显的差异，不同方位的回击磁场峰值差异达到2～4倍。与假定通道笔直的回击模型相比，分形闪电通道模型能很好地再现回击过程电磁辐射的高频分量和次峰等细微现象。
Based on the lightning channel observed with a high-speed digital image system, the fractal lightning channel model is formulated with the fractal method. In this paper, we analyse the effect of lightning channel tortuosity on the corresponding electromagnetic fields in different azimuths and different distances. The results show that, at close distances （100 m--10 km）, the ratio of EF（ electric field） peaks at any two azimuths is within 0. 8--2.3. With the increase of distance, the dependence on azimuth weakens. However,the dependence of MF（ magnetic field） waveforms on azimuth is obvious, and the ratio of MF peaks at any two azimuths ranges about from 2 to 4. Compared with the return stroke model assuming a straight lightning of negligible cross section, the fractal channel model can well simulate the fine structure of the radiation fields, whose time-domain behavior exhibits a jagged shape with remarkable spectral content in several bands of fractal interest.
出处
《大气科学学报》
CSCD
北大核心
2010年第6期719-724,共6页
Transactions of Atmospheric Sciences
基金
国家自然科学基金资助项目(40975002)
中国科学院知识创新工程领域前沿项目(IAP09313)
江苏省高校自然科学基金资助项目(09KJB170005)
公益性行业科研专项(GYHY200806014)
关键词
回击
通道形状
分形
垂直电场
辐射场
return stroke
channel tortuosity
fractal
vertical electric field
radiation field
