Lightning and Thunderstorm Studies

闪电和雷暴研究

• 批准号: 2214044
• 负责人: Paul Krehbiel
• 金额: $ 109.2万
• 依托单位: New Mexico Institute of Mining and Technology
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-07-01 至 2025-06-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2214044&HistoricalAwards=false
• 关键词: Lightning; Thunderstorm; Studies

This research focuses on furthering our understanding of how lightning is produced inside thunderstorms, and how some lightning flashes occasionally produce strong bursts of gamma rays. Gamma rays are similar to but much more powerful than x-rays, and studying how they are produced helps us better understand how lightning begins and develops. The bursts, called terrestrial gamma-ray flashes (TGFs), were first detected by satellites, and are upward-directed events caused by in-cloud (IC) lightning. Although upward TGFs continue to be detected by satellites, the detection rate at any given location is very low, and there have been no close observations of IC flashes that produced satellite-detected TGFs. More recently, studies at the large-area cosmic ray-detecting Telescope Array facility in west-central Utah have shown that cloud-to-ground (CG) lightning can produce downward TGFs. The studies, which are being conducted in collaboration with colleagues at the University of Utah, have provided the first detailed observations of how TGFs are produced by lightning, and are to be expanded upon in the studies going forward. At the same time, similar studies are to be conducted at the Kennedy Space Center in Florida, where there is a greater chance of obtaining observations of IC flashes that produce satellite-detected TGFs. The studies are important because they advance our understanding not only about how TGFs are produced, but also provide valuable information about the lightning discharge processes themselves. They are also cross-disciplinary, in this case between traditional lightning investigations and high-energy particle physics, and provide excellent learning opportunities and experiences for graduate and undergraduate students. The studies utilize observational data obtained from a comprehensive set of lightning detection techniques and systems, including lightning mapping arrays (LMAs) that use multi-station time-of-arrival measurements of the VHF radio signals produced by lightning to determine the 3-D structure and development of flashes, and dual broadband VHF interferometer systems that show the detailed development of flashes continuously in time, with sub-microsecond resolution. Combined with high-speed measurements of the electric field change produced by the different discharge processes, the observations provide complete pictures of the development of lightning flashes both in time and space. The Telescope Array detects Compton electrons produced by the gamma-ray bursts, not only with sub-microsecond resolution and continuously over time, allowing the TGFs to be accurately correlated with the lightning data, but also with 1.2 km grid spacing over tens of kilometers extent – a major factor in detection efficiency. The comparisons show the TGFs occur during energetic initial breakdown pulses (IBPs) of CG flashes, and are playing a crucial role in understanding how IBPs are produced and their effect on how lightning is initiated and continues to develop. The combination of large areal extent and continuous time coverage of the Utah study allows several to ten or more TGFs to be detected in a given summer monsoon season. Similarly continuous coverage of the lightning activity will be obtained in the east central Florida area around Kennedy Space Center, which has a much higher incidence of lightning and thunderstorms, and is within the latitudinal coverage range of the orbiting TGF-detecting satellites.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

这项研究的重点是加深我们对雷暴中闪电是如何产生的，以及一些闪电是如何偶尔产生强烈的伽马射线爆发的理解。伽马射线类似于X射线，但比X射线更强大，研究它们是如何产生的有助于我们更好地了解闪电是如何开始和发展的。这种被称为地面伽马射线闪光（TGFs）的爆发首先由卫星探测到，是由云内（IC）闪电引起的向上事件。虽然卫星继续探测到向上的TGF，但在任何给定位置的探测率都非常低，并且没有近距离观测到产生卫星探测到的TGF的IC闪光。最近，位于犹他州中西部的大面积宇宙射线探测望远镜阵列设施的研究表明，云对地（CG）闪电可以产生向下的TGF。这些研究是与犹他州大学的同事合作进行的，他们提供了闪电如何产生TGF的第一个详细观察结果，并将在未来的研究中得到扩展。与此同时，类似的研究将在佛罗里达的肯尼迪航天中心进行，那里有更大的机会获得对产生卫星探测到的TGF的IC闪光的观测。这些研究很重要，因为它们不仅促进了我们对TGF如何产生的理解，而且还提供了有关闪电放电过程本身的宝贵信息。 它们也是跨学科的，在这种情况下，传统的闪电调查和高能粒子物理之间，并为研究生和本科生提供良好的学习机会和经验。这些研究利用了从一套全面的闪电探测技术和系统获得的观测数据，包括闪电测绘阵列（LMA），该阵列使用闪电产生的VHF无线电信号的多站到达时间测量来确定闪电的三维结构和发展，以及双宽带VHF干涉仪系统，该系统及时连续显示闪电的详细发展，分辨率为亚微秒。结合对不同放电过程产生的电场变化的高速测量，这些观测提供了闪电在时间和空间上发展的完整图像。望远镜阵列探测伽马射线爆发产生的康普顿电子，不仅具有亚微秒分辨率，而且随着时间的推移持续不断，使TGFs与闪电数据准确相关，而且在数十公里范围内具有1.2公里的网格间距-这是探测效率的主要因素。比较表明，TGFs发生在CG闪光的高能初始击穿脉冲（IBP）期间，并且在理解IBP如何产生及其对闪电如何启动和继续发展的影响方面发挥着至关重要的作用。犹他州研究的大面积范围和连续时间覆盖相结合，允许在给定的夏季季风季节检测到几个到十个或更多的TGF。在肯尼迪航天中心周围的佛罗里达中东部地区，闪电活动也将得到同样的连续覆盖，该地区闪电和雷暴的发生率要高得多，并且在轨道TGF探测卫星的纬度覆盖范围内。这一奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

First High‐Speed Video Camera Observations of a Lightning Flash Associated With a Downward Terrestrial Gamma‐Ray Flash

第一个高速摄像机观测到与向下的地面伽马射线闪光相关的闪电

• DOI: 10.1029/2023gl102958
• 发表时间: 2023
• 期刊: Geophysical Research Letters
• 影响因子: 5.2
• 作者: Abbasi, R. U.;Saba, M. M. F.;Belz, J. W.;Krehbiel, P. R.;Rison, W.;Kieu, N.;da Silva, D. R.;Stanley, M. A.;Rodeheffer, Dan;Remington, J.
• 通讯作者: Remington, J.

Analysis of the Configuration Relationship Between the Morphological Characteristics of Lightning Channels and the Charge Structure Based on the Localization of VHF Radiation Sources

• DOI: 10.1029/2022gl099586
• 发表时间: 2022-07
• 期刊: Geophysical Research Letters
• 影响因子: 5.2
• 作者: Yurui Li;Yang Zhang;Yijun Zhang;P. Krehbiel

An Improved Method for Analyzing Broadband VHF Interferometer Lightning Observations

• DOI: 10.1109/tgrs.2023.3299368
• 发表时间: 2023
• 期刊: IEEE Transactions on Geoscience and Remote Sensing
• 影响因子: 8.2
• 作者: Xiangpeng Fan;P. Krehbiel;M. Stanley;W. Rison;H. Edens;Yijun Zhang