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

合作研究：闪电对电离层多方面影响的定量分析

• 批准号: 1451210
• 负责人: Mark Golkowski
• 金额: $ 24.5万
• 依托单位: University of Colorado at Denver
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-09-01 至 2018-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1451210&HistoricalAwards=false
• 关键词: Collaborative; Research; Quantitative; Analysis; Lightning

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.

该奖项解决了有关雷电对较低电离层（60-90公里）的影响的基本问题。闪电放电是静电场和电磁辐射的最强大来源之一，已知会在下部电离层中产生重大干扰。具体而言，两种有据可查的扰动源于直接加热（称为早期/快速（E/F）事件），或者来自辐射带的能量颗粒诱导的轰击，被称为闪电诱导的电子沉淀（LEP）。低电离层的低环境电子密度阻止了标准雷达技术的直接测量，因此，使用非常低频率（VLF，3-30 kHz）波从强大的通信发射机中观察E/F和LEP事件。 VLF信号反映了较低的电离层，当电离层沿路径发生电离层扰动时会在幅度和相位上扰动，从而允许连续观察形式。迄今为止，诊断和理解障碍物理学的努力在很大程度上取得了定性的结果。该项目将汇集两名在电离层和磁层过程中的专家，以实现VLF遥感的全部潜力。由于雷电引起的干扰，该项目将加强预测导航和沟通中断的努力。每个机构的早期职业生涯将领导该项目，这也将为几位研究生和一名博士后研究人员的支持做出贡献。由于VLF信号传播的复杂性质以及闪电放电的可变性，由于缺乏VLF信号扰动的电离层干扰物理学的明确测定。在这项工作中，通过引入以下创新来量化Lightning-Ionosphere与VLF遥感耦合的挑战：1。基于海洋的闪电和重叠的VLF发射机路径的战略观察。 2。从两个通道中振幅和相位的新型极化和散射场分析3。量化闪电源光谱在电离层干扰中的作用4。改进跨离子层传播和射线座的数值代码。