Using Powerful, Low-Frequency Radio Waves from Lightning to Diagnose the D-region Ionosphere

该项目将利用3-300千赫的闪电射电辐射作为探测器，研究海拔低于95公里的D区电子密度。特别是，新技术将被用于分析被称为窄双极事件的闪电射电发射，以便提供类似于电离仪的电子密度分布以及关于太阳耀斑、粒子降水和雷暴引起的D区扰动的垂直和水平结构的信息。主要研究任务是开发一个改进的全波传播模型，该模型将提供更详细的电离层参数提取；将这一技术应用于存档事件，以确定各种条件下D区域电离层的基线变率；并将其应用于结果，以解决有关辐射带动力学和闪电-电离层相互作用的公开问题。理论电磁模型将根据由不同位置的多个宽带接收器同时探测到的闪电产生的无线电波的传播情况进行测试。该模型的应用将能够推断D区在垂直方向上的水平定域、瞬时电子密度分布。这将在各种地球物理条件下以及磁层和行星际扰动、太阳耀斑和闪电本身等外部影响造成的时间变化下进行研究。将进行的任务包括：1)开发利用来自“窄双极事件”闪电放电的3-300 kHz辐射的改进的电离层无线电探测技术；2)利用改进的探测技术，研究在安静、不受干扰的条件下D区域电子密度分布的垂直结构；3)研究由于太阳耀斑活动、磁层高能粒子降水和由附近雷暴的静电场以及通过闪电辐射电磁脉冲产生的电子加热而产生的D区域扰动的垂直和水平结构。将使用的数据库包括全球闪电定位网络(WWLLN)和洛斯阿拉莫斯科学阵列。一名研究生将参与这个项目。

This project will study the D-region electron density, at altitudes less than 95 km, using 3-300 kHz lightning radio emissions as a probe. In particular, new techniques will be applied to analysis of lightning radio emissions known as Narrow Bipolar Events in order to provide ionosonde-like retrievals of electron density profiles as well as information on the vertical and horizontal structure of D-region perturbations due to solar flares, particle precipitation, and thunderstorms. The primary research tasks are to develop an improved full wave propagation model which will provide more detailed ionospheric parameter extraction; to apply this technique to archived events to establish baseline D region ionospheric variability under a variety of conditions; and to apply to the results to open questions regarding radiation belt dynamics and lightning-ionosphere interactions. The theoretical electromagnetic model will be tested against observations of the propagation of lightning-generated radio waves detected simultaneously by multiple wide-band receivers at varying locations. Application of the model will enable inference of the D-region's horizontally-localized, instantaneous electron density profile in the vertical direction. This will be studied under a variety of geophysical conditions as well as the time variations caused by external influences such as magnetospheric and interplanetary disturbances, solar flares, and lightning itself. The tasks to be performed include: 1) Development of improved ionospheric radio-sounding technique using 3-300 kHz radiation from "Narrow Bipolar Event" lightning discharges; 2) Study of the vertical structure of D-region electron density profile in quiet, undisturbed conditions, using the improved sounding technique; 3) Study of vertical and horizontal structure of D-region perturbations due to solar flare activity, magnetospheric energetic particle precipitation and electron heating by the electrostatic fields of nearby thunderstorms and by electron heating by the radiated electromagnetic pulse of lightning strokes. The databases to be used includes the World Wide Lightning Location Network (WWLLN) and the Los Alamos Sferic Array. A graduate student will participate in the project.