利用强烈闪电VLF/LF信号的电离层D层观测研究

Due to the great difficulty in detecting technique，knowledge on ionospheric D region is quite inadequate.However,a novel method is currently proposed to measure and diagnose the lower ionosphere by using intense lightning signals. In this project, a GPS-based 6-station network in Jianghuai area as well as one remote sensor in Conghua(Guangzhou) will be setup to synchronously record VLF/LF radiation waveforms from lightning discharges.The sources of lightning signals will be obtained by time of arrival locating technique.For those located sources,their remote VLF waveforms as recorded in Conghua will be used to remote sense the electron density profile along the VLF-propagating path.Time-domain waveforms of return strokes and NBEs will be also used to probe the high temporal and spatial-resolution detection of D-layer fluctions as well as the response of ionospheric D region to lightning discharges.The results of this project is sure to enrich the knowledge on ionospheric D region.

由于探测技术手段的局限，当前对于电离层D层的探测研究还相当不充分。利用强烈闪电VLF/LF信号探测和诊断电离层D层是当前电离层探测技术的新领域。本申请研究基于江淮地区闪电站网系统记录的闪电VLF/LF信号波形以及广州从化站同步记录的远场VLF闪电信号波形，开展中国东部地区电离层D层平均电子密度廓线反演及其时空变化研究，同时基于站网系统记录的地闪回击和NBE波形开展局地电离层D层特性不均匀性研究，以及电离层D层与雷暴放电相互作用研究。这一研究将扩展当前国内对于电离层D层的探测手段，研究结果也将丰富对于电离层D层特性的认识。

目前学术界正在开展利用闪电放电产生的VLF/LF电磁波信号的电离层D层探测技术研究。利用具有闪电VLF/LF波形记录能力的观测站网，通过分析雷暴连续活动期间的闪电波形资料，揭示电离层D层特征的时空变化特征。本项目研究改造现有的江淮地区闪电VLF/LF信号观测网，发展了基于射线追踪算法的利用闪电VLF/LF信号的电离层D层电子密度廓线反演算法，发展了针对地闪回击和NBE的电离层反射波自动识别的电离层反射高度快速反演算法。个例分析结果表明，电离层 D 层对太阳辐射的响应存在2-4分钟的时间滞后，而且日出和日落期间电离层D层响应存在非对称性。同时利用站网观测丰富闪电过程波形资料开展闪电物理学和现象学研究。