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.

该项目旨在了解地面伽马射线闪光 (TGF) 何时、何地以及为何伴随闪电。 TGF 是一种强烈的高能辐射爆发，是当地球下方发生雷暴时，绕地球运行的卫星首次发现的。 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类造成健康风险。 也许最神秘的是，绝大多数闪电不会产生转化生长因子，而我们还不知道那些产生转化生长因子的闪电有什么特别之处。 大多数已观测到的 TGF 都是向上射向太空的，但也有向下的 TGF ，观测到的 TGF 要少得多，而且似乎与非常不同类型的闪电有关。 辐射传感器将部署到世界各地闪电丰富但又多样化的环境中——高海拔和低海拔地区，以及夏季闪电和冬季闪电强烈的地区。 TGF 检测和未检测将与显示发生了何种闪电的无线电波数据进行比较。 这将有助于确定何时最有可能出现 TGF，并有助于了解它们是如何发生的。部署地点将包括瑞士的桑蒂斯山和日本的富士山，最近的研究表明，夏季闪电会在这些地方产生TGF 和日本西海岸，多年来人们都知道那里的冬季雷暴会在接近地面的地方产生 TGF。 这些环境中的 TGF 是由正云内闪电和负云内闪电、自然负云对地闪电以及由塔上向上的正先导引发的负云对地闪电产生的。 观测将使用新开发的探测器阵列进行，这些探测器阵列具有精确（微秒）定时和各种尺寸的探测器，以显着提高动态范围（以便可以轻松地表征微弱/远处和明亮/附近的 TGF）。 新型探测器将与现有探测器一起部署；这是一款具有亚秒级时间分辨率的数字剂量计，可量化 TGF 的辐射剂量，其精确度足以使所有传统探测器进入饱和或关闭状态。 将搜索 TGF 和相关 sferics 的特征，以找出与云对地和云内闪电相关的 TGF 之间的系统差异； TGFs 与独特的强 sferics 相关，并且与仅具有弱 sferics 相关；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产生机制（例如，不同几何形状的相对论反馈与领导者产生种子电子）。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力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