起伏海面的雷电电磁场传播特征及其对闪电定位精度的影响

为了研究起伏海面对雷电电磁传播的影响,本文利用Barrick表面阻抗理论和Wait近似算法,采用改进二维分形海面模型模拟起伏海面,利用数值模式,分析起伏海面的雷电电磁传播特征,并进一步讨论了起伏海面对时差法闪电定位系统定位精度的影响。结果表明:起伏海面对垂直电场和磁场的峰值的影响不显著,但会引起波形的上升期时间的延长,浪高越大,影响越明显;随着观测距离的增加,雷电垂直电场波形的上升时间逐渐变长;风速的变化与雷电垂直电场波形的上升时间成正比;由于海面起伏引起雷电电磁场波形在传播中的变化会影响基于时差法闪电定位系统的定位精度,定位误差可达几至十几公里。

Propagation characteristics of the lightning electromagnetic fields along rough sea surface and the effects on the accuracy of ToA-based lightning location

An improved two-dimensional fractal model was used to describe the rough sea surface, and based on Barrick''s formulations and Wait''s formulations, this paper selected a lightning stroke to analyze the lightning electromagnetic field along the rough sea surface. Furthermore, the effects of the sea surface fluctuation on the time-of-arrival (ToA)-based lightning location systems (LLS) were discussed. The results revealed that the sea surface fluctuation had a significant effect on the wave shape and time delay of the electromagnetic fields propagating along the rough sea surface, but had little effect on the magnitude of the electromagnetic fields. The rise time of the wave shape became longer with an increase in the wave height. When the observation distance increased, the rise times of the lightning vertical electric fields and magnetic fields became longer. The observed time delay caused by the electromagnetic field propagation along the rough sea surface might impact the location accuracy of ToA-based LLS. Affected by the sea surface, different lightning stroke points lead to different lightning location errors, and the location error reached several to ten kilometers.