Global Exploration of the Conditions of Downward Terrestrial Gamma-ray Flash (TGF) Production

全球向下地面伽马射线闪光（TGF）产生条件的探索

• 批准号: 2235299
• 负责人: David Smith
• 金额: $ 81.03万
• 依托单位: University of California-Santa Cruz
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-02-01 至 2026-01-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2235299&HistoricalAwards=false
• 关键词: Global; Exploration; Conditions; Downward; Terrestrial

This program seeks to understand when, where, and why terrestrial gamma-ray flashes (TGFs) accompany lightning. TGFs are intense bursts of high-energy radiation that were first discovered by satellites orbiting Earth when thunderstorms were taking place below. They emit enough radiation to pose a health risk to humans aboard an aircraft within a few hundred meters of the region of energy release. Perhaps most mysteriously of all, the vast majority of lightning flashes don't produce a TGF, and we don't yet understand what's special about the ones that do. Most of the TGFs that have been observed have been directed upward toward space, but there are also downward TGFs, which have had far fewer observations and appear to be associated with very different types of lightning. Radiation sensors will be deployed to environments around the world that are all rich in lightning but otherwise diverse -- high and low altitude sites, and sites with strong summer lightning and strong winter lightning. TGF detections and non-detections will be compared with data on radio waves that show what kind of lightning occurred. This will help sort out when TGFs are most likely to be expected, lending insight as well into how they happen.Deployment sites will include Mt. Santis in Switzerland and Mt. Fuji in Japan, where it has very recently been shown that summertime lightning produces TGFs, and the west coast of Japan, where it has been known for several years that winter thunderstorms produce TGFs close to the ground. TGFs in these environments have been produced by positive and negative intracloud lightning, by natural negative cloud-to-ground lightning, and by negative cloud-to-ground lightning initiated by an upward positive leader from a tower. Observations will be made with newly developed detector arrays that have accurate (microsecond) timing and detectors of a range of sizes to dramatically improve dynamic range (so that faint/distant and bright/nearby TGFs can be easily characterized). A new type of detector will be deployed alongside the existing ones; this is a digital dosimeter with sub-second time resolution that will quantify the radiation dose from TGFs so close that all the conventional detectors go into saturation or shut down. Characteristics of the TGFs and associated sferics will be searched for systematic differences between TGFs associated with cloud-to-ground and intra-cloud lightning; TGFs associated with uniquely powerful sferics and those with only weak sferics; and, from the other perspective, characteristics of lightning that produces TGFs versus lightning that doesn't, all with the goal of clarifying the production mechanisms (e.g. relativistic feedback in different geometries versus production of seed electrons by leaders).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.

该计划旨在了解何时，何地以及为什么地面伽马射线闪光（TGFs）伴随闪电。 TGFs是一种高能辐射的强烈爆发，最初是由绕地球运行的卫星在雷暴发生时发现的。 它们发出的辐射足以对能量释放区域几百米范围内的飞机上的人构成健康风险。 也许最神秘的是，绝大多数的闪电不会产生TGF，我们还不知道那些会产生TGF的闪电有什么特别之处。 大多数被观测到的TGF都是向上指向太空的，但也有向下的TGF，它们的观测数量要少得多，似乎与非常不同类型的闪电有关。 辐射传感器将部署在世界各地的环境中，这些环境都富含闪电，但在其他方面也各不相同-高海拔和低海拔地点，以及夏季闪电和冬季闪电都很强的地点。 TGF检测和未检测将与无线电波数据进行比较，以显示发生了什么样的闪电。 这将有助于找出何时最有可能出现TGF，并深入了解它们是如何发生的。瑞士的桑蒂斯山在日本的富士山，最近发现夏季闪电会产生TGF，在日本的西海岸，几年前就知道冬季雷暴会在靠近地面的地方产生TGF。 在这些环境中的TGFs已产生的正和负的云内闪电，自然负的云地闪电，和负的云地闪电由一个向上的正领导人从塔发起。 观测将使用新开发的探测器阵列进行，这些阵列具有精确的（微秒）定时和一系列大小的探测器，以显着提高动态范围（以便可以轻松地表征微弱/遥远和明亮/附近的TGF）。 一种新型的探测器将与现有的探测器一起部署;这是一种具有亚秒时间分辨率的数字剂量计，它将量化TGF的辐射剂量，使所有传统探测器进入饱和或关闭。 将研究TGFs和相关天电体的特征，以寻找与云对地和云内闪电相关的TGFs之间的系统差异;与独特的强天电体相关的TGFs和仅与弱天电体相关的TGFs;从另一个角度来看，产生TGF的闪电与不产生TGF的闪电的特征，所有这些都是为了澄清生产机制（例如，不同几何结构中的相对论反馈与先导产生的种子电子）该奖项反映了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

Mountaintop Gamma Ray Observations of Three Terrestrial Gamma‐Ray Flashes at the Säntis Tower, Switzerland With Coincident Radio Waveforms

在瑞士桑蒂斯塔对三个地面伽马射线闪光进行的山顶伽马射线观测，无线电波形一致

• DOI: 10.1029/2023jd039761
• 发表时间: 2024
• 期刊: Journal of Geophysical Research: Atmospheres
• 作者: Chaffin, Jeffrey M.;Smith, David M.;Lapierre, Jeff;Cummer, Steve;Ortberg, John;Sunjerga, Antonio;Mostajabi, Amirhossein;Rubinstein, Marcos;Rachidi, Farhad
• 通讯作者: Rachidi, Farhad

Determining a Lower Limit of Luminosity for the First Satellite Observation of a Reverse Beam Terrestrial Gamma Ray Flash Associated With a Cloud to Ground Lightning Leader

确定与云对地闪电先导相关的反向光束地面伽马射线闪光的首次卫星观测的光度下限

• DOI: 10.1029/2023jd038885
• 发表时间: 2023
• 期刊: Journal of Geophysical Research: Atmospheres
• 作者: Chaffin, Jeffrey M.;Pu, Yunjiao;Smith, David M.;Cummer, Steve;Splitt, Michael
• 通讯作者: Splitt, Michael

Two Laterally Distant TGFs From Negative Cloud‐To‐Ground Strokes in Uchinada, Japan

日本内田的两个横向距离的 TGF 从负云到地面中风

• DOI: 10.1029/2023jd039020
• 发表时间: 2024
• 期刊: Journal of Geophysical Research: Atmospheres
• 作者: Ortberg, John;Smith, David M.;Kamogawa, Masashi;Dwyer, Joseph;Bowers, Gregory;Chaffin, Jeffrey;Lapierre, Jeff;Wang, Daohong;Wu, Ting;Suzuki, Tomoyuki
• 通讯作者: Suzuki, Tomoyuki