CEDAR: High Speed Spectroscopic Studies of lightning bolts: Starters, Jets, and Gigantic Jets

CEDAR：闪电的高速光谱研究：启动器、喷射流和巨型喷射流

• 批准号: 1552177
• 负责人: Ningyu Liu
• 金额: $ 45.64万
• 依托单位: Florida Institute of Technology
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-02-01 至 2017-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1552177&HistoricalAwards=false
• 关键词: CEDAR; Speed; Spectroscopic; Studies; lightning

The Coupling, Energetics, and Dynamics of Atmospheric Regions (CEDAR) program, a broad-based, community-guided, upper atmospheric research program, seeks to understand the behavior of atmospheric regions from the lower atmosphere upward through the ionized upper layers of the atmosphere. Of particular interest is the question of the scale of coupling of the lower atmosphere, where phenomena such as thunderstorms exist, to the ionized layer near 100-120 km. The physics of lightning phenomenology within thunderstorm events are very complex and highly time-dependent with complex morphology characterizing the coupling of lightning bolts to the ionosphere with consequential significant temporal behavior of the ionized density of the lower ionosphere region. These electrical discharges are initiated inside thunderstorms and are rooted in one of the main thundercloud charge layers. This award would study the physical processes underlying the particular transient lightning bolt structures referred to as blue starters, jets, and gigantic jets, which are the upward electrical discharges from thunderstorms that terminate at 20-30 km, 40-50 km and 70-90 km altitude, respectively. These are generated suddenly within a fraction of a second from thunderstorms. The research supported by this award would examine the energetics and dynamics of these TIL (Transient Luminous Event) phenomena. Typically, the initial vertical development has a speed of ~100 km/s, but after 100-300 ms, the upward discharge leading to gigantic jets suddenly accelerates to reach the lower ionosphere with a speed greater than 1000 km/s. The funded research would be primarily observational involving the construction of a high-speed (5,000 frames per second) spectrograph that can analyze the energetics of the jets and starters through the fast acquisition of visible atomic and molecular spectra allowing high-speed measurements of the relative intensities of the red-to-blue colors emitted by the lightning bolt along its path between the storm and the ionized layer. Analysis of these spectra would provide the time variations of the vertical temperature profile within the ionized air pathway of the lightning bolt. This information about the temperature profile would be used to quantify the energetics underlying the formation of these morphological features of the lightning bolt. This award has the potential of transformative research that would provide a major advance in the knowledge and understanding of the physics of transient plasma discharges which should prove to be extremely valuable and of high importance to the study of laboratory electrical discharges and tropospheric lightning investigations; such findings would be of great value to other disciplines such as power transformers, laser fusion research, and plasma discharge systems. The award would support significant activity in STEM education and student training similar to that recently conducted by the PI and his group. Finally, this award has a strong potential of attracting public attention via local TV and newspaper interviews. The grant awardees indicated also that they would provide the public with excellent public access to the research with frequent open lectures that would generate strong interest by the public in lightning phenomena.The award represents a strong potential for exciting and transformative science. The proposed research would examine in detail fundamental science questions that are related to jet and starter dynamics and their electrical coupling between the lower atmosphere and ionosphere. Moreover, the proposed observational approach is sophisticated providing critical high-time resolution spectral information on the spectral properties of starters and jets that would be studied to produce height profiles of temperature along the path of the conductive path between the top side of the thunderstorm and the lower ionosphere region established by the lightning bolt.

耦合，能量学和大气区域动力学（CEDAR）计划是一个基础广泛的，社区指导的高层大气研究计划，旨在了解从低层大气向上通过电离层上层大气的大气区域的行为。特别令人感兴趣的是存在雷暴等现象的低层大气与100-120公里附近电离层耦合的规模问题。雷暴事件中的闪电现象的物理学是非常复杂的，并且高度依赖于时间，复杂的形态表征了闪电与电离层的耦合，从而导致低电离层区域电离密度的显着时间行为。 这些放电是在雷暴内部开始的，并植根于一个主要的雷暴云电荷层。该奖项将研究被称为蓝色启动器、喷流和巨型喷流的特定瞬态闪电结构的物理过程，这些结构是雷暴的向上放电，分别终止于20-30公里、40-50公里和70-90公里的高度。 这些都是雷暴在几分之一秒内突然产生的。该奖项支持的研究将研究这些TIL（瞬态发光事件）现象的能量学和动力学。通常，最初的垂直发展速度约为100 km/s，但在100-300 ms之后，导致巨大喷流的向上放电突然加速，以大于1000 km/s的速度到达低电离层。受资助的研究将主要是观测性的，包括建造一台高速（每秒5,000帧）摄谱仪，通过快速获取可见原子和分子光谱来分析喷流和启动器的能量，从而高速测量闪电沿着其在风暴和电离层之间的路径发射的红到蓝颜色的相对强度。对这些光谱的分析将提供闪电电离空气路径内垂直温度分布的时间变化。关于温度分布的信息将被用来量化形成闪电的这些形态特征的能量学。 这一奖项具有变革性研究的潜力，将在瞬态等离子体放电物理学的知识和理解方面取得重大进展，这将证明对实验室放电研究和对流层闪电调查极为宝贵和重要;这些发现对其他学科，如电力变压器、激光聚变研究和等离子体放电系统等都有很大的价值。 该奖项将支持STEM教育和学生培训方面的重要活动，类似于PI及其团队最近开展的活动。 最后，该奖项具有通过当地电视台和报纸采访吸引公众关注的强大潜力。 获奖者还表示，他们将为公众提供良好的公众访问研究与频繁的公开讲座，将产生强烈的兴趣，由公众在闪电现象。该奖项代表了一个令人兴奋的和变革性的科学的强大潜力。拟议的研究将详细审查与喷流和起动器动力学及其低层大气与电离层之间的电耦合有关的基本科学问题。 此外，拟议的观测方法是复杂的，提供了关于起动器和喷流光谱特性的关键高时间分辨率光谱信息，将对这些信息进行研究，以产生沿雷暴顶面和闪电形成的低电离层区域之间传导路径沿着的温度高度分布图。