CEDAR: Natural and Rocket-Triggered Lightning in the Mesosphere-Lower Thermosphere-Ionosphere (MLTI) System

该研究项目将定量调查60至100公里高度的大气层中间层-低热层电离层(MLTI)区域自然闪电和火箭触发闪电的影响。实验工作将侧重于关于由自然闪电产生统称为瞬变发光事件(TLE)的发光现象的几个悬而未决的问题，并将调查火箭引发的闪电作为这些干扰的来源可能起到的作用。主要的理论工作将结合最先进的数值模式来预测中层/电离层对真实回击电流的反应，这与观测结果一致。实验工作集中在佛罗里达州布朗德营地国际闪电研究和测试中心(ICLRT)及其附近观测到的闪电。该项目将提供对自然闪电波形和火箭引发的闪电波形的同步宽带(1赫兹-20兆赫)观测，对瞬变发光事件进行光学探测的光度观测，以及对对D区电离层电导率变化敏感的甚低频(VLF，3-30千赫)信号的窄带(200赫兹带宽)观测。这些系统将在授标的三年期间持续监测与自然闪电有关的电离层事件。使用经典的火箭和电线技术触发闪电的尝试将在强烈的夜间雷雨期间进行。该计划将解决以下问题：1)成功产生TLE的闪电的宽带(1赫兹-20 MHz)特征是什么？2)成功产生电离层电导率变化并散射VLF信号的闪电的宽带特征是什么？3)TLE的哪些特征与观测到的VLF散射最密切相关？

The research project will quantitatively investigate the effects of both natural and rocket-triggered lightning in the mesosphere-lower thermosphere-ionosphere (MLTI) region of the atmosphere between 60 and 100 km altitude. The experimental effort will focus on several outstanding questions regarding the production of light-emitting phenomena known collectively as transient luminous events (TLEs) by natural lightning and will investigate the possible role of rocket-triggered lightning as a source for these disturbances. The primary theoretical effort will combine state-of-the-art numerical models to predict the mesospheric/ionospheric reaction to realistic return-stroke currents consistent with observations. The experimental effort centers on lightning observed at and near the International Center for Lightning Research and Testing (ICLRT) in Camp Blanding, Florida. The project will provide simultaneous wideband (1 Hz-20 MHz) observations of the causative lightning waveforms (both natural and rocket-triggered), photometric observations for the optical detection of transient luminous events, and narrowband (200-Hz bandwidth) observations of very low frequency (VLF, 3-30 kHz) signals that are sensitive to conductivity changes in the D-region ionosphere. These systems will provide continuous monitoring of ionospheric events related to natural lightning throughout the three-year period of the award. Attempts to trigger lightning using the classical rocket-and-wire technique will be performed during intense nighttime thunderstorms. This program will address the following questions: 1) What are the wideband (1 Hz-20 MHz) characteristics of lightning that successfully produce TLEs? 2) What are the wideband characteristics of lightning that successfully produce ionospheric conductivity changes that scatter VLF signals? 3) What characteristics of TLEs are most closely associated with the observed VLF scattering?