Collaborative Research: CEDAR--Tomographic Array for Lightning and Ionospheric Studies (TALIS)

合作研究：CEDAR——用于闪电和电离层研究的断层扫描阵列 (TALIS)

• 批准号: 1025262
• 负责人: Sigrid Elschot
• 金额: $ 11.4万
• 依托单位: Stanford University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-12-15 至 2012-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1025262&HistoricalAwards=false
• 关键词: Collaborative; Research; CEDAR; Tomographic; Array

In order to fully characterize the effect of lightning on ionospheric density structures, this project will deploy co-located ionosphere and lightning RF arrays at HF (1-30 MHz) for D- and E-region imaging, and VLF (0-500 kHz) and VHF (120-150 MHz) radars for lightning studies. The observational program will be augmented by computations from the Ionospheric Data Assimilation Four-Dimensional (IDA4D) model. The model will perform tomographic reconstruction of the ionosphere for heights extending from the E region to above using the observations obtained as well as other opportunistic E region data sources, most notably from the Los Alamos Portable Pulser (LAPP) with the Cibola Flight Experiment (CFE) satellite. The goal of these activities is to elucidate coupling processes between the troposphere and ionosphere, in particular the interaction between lightning and E region ionization enhancements known as sporadic-E. Current thinking suggests that there are two primary mechanisms that transport energy from the troposphere to the lower ionosphere: the first is mechanical wave activity and the second is electrical effects associated with lightning, including electromagnetic pulses and relativistic electrons. The mechanical coupling of waves may increase the peak plasma densities of sporadic-E layers before propagating into the F-region. Discharges from lightning couple electromagnetically and may increase the peak plasma densities by creating more long-lived metal ions from the ambient population of meteoric metal atoms found at these altitudes. However, very little is known about the electromagnetic coupling between lightning and the ionosphere, even though observations of Transient Luminous Events (TLE) indicate that interactions between thunderstorms and the middle and upper atmospheres do occur. The goal is to make significant progress in answering the following questions on ionosphere/troposphere coupling: (1) What is the coupling mechanism between lightning emissions and the development of sporadic E layers? (2) What is the relationship between lightning emissions and the variations of conductances in the ionosphere? (3) To what degree can we use measured RF values of the lightning emissions and characterization of the ionosphere to simultaneously model and analyze the physical characteristics of lightning emissions and the detailed structuring of the ionospheric response?

为了充分表征闪电对电离层密度结构的影响，该项目将部署高频（1-30 MHz）电离层和闪电射频阵列，用于D区和e区成像，并部署VLF （0-500 kHz）和VHF （120-150 MHz）雷达进行闪电研究。观测计划将通过电离层数据同化四维（IDA4D）模型的计算得到加强。该模型将利用所获得的观测数据以及其他机会性的E区数据源（最值得注意的是来自带有Cibola飞行实验（CFE）卫星的洛斯阿拉莫斯便携式脉冲发生器（LAPP））对从E区到以上高度的电离层进行层状重建。这些活动的目标是阐明对流层和电离层之间的耦合过程，特别是闪电与E区电离增强之间的相互作用，即散发性E。目前的想法表明，有两种主要的机制将能量从对流层传输到较低的电离层：第一种是机械波活动，第二种是与闪电有关的电效应，包括电磁脉冲和相对论电子。在传播到f区之前，波的机械耦合可能会增加零星e层的峰值等离子体密度。闪电的放电以电磁耦合的方式发生，并可能通过在这些高度发现的大气金属原子的环境种群中产生更长寿的金属离子而增加峰值等离子体密度。然而，人们对闪电和电离层之间的电磁耦合知之甚少，尽管对瞬变发光事件（TLE）的观测表明雷暴和中高层大气之间的相互作用确实发生过。目标是在回答电离层/对流层耦合的以下问题方面取得重大进展：(1)闪电发射与零星E层发展之间的耦合机制是什么？(2)电离层电导变化与闪电辐射有何关系？(3)在多大程度上，我们可以利用闪电发射的射频测量值和电离层的特征来同时模拟和分析闪电发射的物理特征和电离层响应的详细结构？