Collaborative Research: Quantitative Analysis of Lightning's Multifaced Impact on the Ionosphere

该奖项旨在解决有关闪电放电对低电离层（60-90公里）影响的基本问题。闪电放电是静电场和电磁辐射的最强大的来源之一，并且已知会在低电离层中产生重大干扰。具体来说，有两种有据可查的扰动要么来自直接加热，称为早/快（E/F）事件，要么来自辐射带高能粒子的诱导轰击，称为闪电诱导电子沉淀（LEP）。低电离层周围电子密度低，无法用标准雷达技术进行直接测量，因此，对E/F和LEP事件的观测是利用大功率通信发射机发出的甚低频（VLF，3-30 kHz）波进行遥感。甚低频信号从低电离层反射，当电离层扰动沿路径沿着发生时，其幅度和相位都会发生扰动，从而可以进行某种形式的连续观测。迄今为止，诊断和理解扰动物理学的努力主要取得了定性结果。该项目将汇集电离层和磁层过程方面的两名专家，以充分发挥甚低频遥感的潜力。该项目将加强对闪电引起的干扰造成的导航和通信中断的预测工作。每个机构的早期职业PI将领导该项目，这也将有助于支持几名研究生和一名博士后研究员。由于甚低频信号传播的复杂性以及闪电放电的多变性，一直缺乏对甚低频信号扰动引起的电离层扰动的物理性质的无环境测定。在这项工作中，量化闪电电离层耦合与甚低频遥感的挑战，通过引入以下创新：1。基于海洋的闪电和重叠甚低频发射机路径的战略观测。2.新的偏振和散射场分析的幅度和相位在两个通道.量化了闪电源频谱在电离层扰动中的作用.跨电离层传播和射线追踪数值程序的改进。

This award addresses fundamental questions about the impact of lightning discharges on the lower ionosphere (60-90 km). Lightning discharges are among the most powerful sources of electrostatic fields and electromagnetic radiation and are known to create significant disturbances in the lower ionosphere. Specifically, two well documented perturbations stem either from direct heating, known as Early/Fast (E/F) events, or from induced bombardment by energetic particles from the radiation belts, known as lightning-induced electron precipitation (LEP). The low ambient electron density of the lower ionosphere precludes direct measurement by standard radar techniques, hence observations of E/F and LEP events are made using remote sensing with Very Low Frequency (VLF, 3-30 kHz) waves from powerful communication transmitters. VLF signals reflect from the lower ionosphere and are perturbed in amplitude and phase when an ionospheric disturbance occurs along the path, thus allowing a form of continuous observation. Efforts to diagnose and understand the physics of disturbances have yielded largely qualitative results to date. This project will bring together two experts in ionospheric and magnetospheric processes to realize the full potential of VLF remote sensing. This project will enhance efforts to forecast navigation and communication outages due to lightning-induced disturbances. Early-career PIs at each institution will lead the project, which will also contribute to the support of several graduate students and a post-doctoral researcher. Unambiguous determination of the physics of ionospheric disturbances from VLF signal perturbations has been lacking due to the complex nature of VLF signal propagation and also the variability of lightning discharges. In this effort, the challenges to quantifying lightning-ionosphere coupling with VLF remote sensing by introducing the following innovations: 1. Strategic observations of ocean-based lightning and overlapping VLF transmitter paths. 2. Novel polarization and scattered field analysis from amplitude and phase in two channels.3. Quantifying the role of the lightning source spectrum in the ionospheric disturbance.4. Improvement of numerical codes for trans-ionospheric propagation and raytracing.