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Lightning Induced Optical Emissions in the Middle Atmosphere

中层大气中的闪电引起的光发射

基本信息

批准号：
08044053
负责人：
WATANABE Shigeto
金额：
$ 2.82万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for international Scientific Research
财政年份：
1996
资助国家：
日本
起止时间：
1996 至 1997
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08044053/
关键词：
thunderstorm stratosphere mesosphere lower ionosphere sprites blue jets elves

项目摘要

Observations of optical phenomena at high altitude above thunderstorms using a multichannel high-speed photometer and image intensified CCD cameras were carried out at Yucca Ridge Station (40゜40'N, 104゜59'W), Colorado. The new measurements indicate that diffuse optical flashes with a duration of <1ms and a horizontal scale of 〜100-300km occur at 75-105km altitude in the lower ionosphere just after the onset of sprites. Here we designate these events as "elves" to distinguish them from "red sprites". This finding is consistent with the production of diffuse optical emissions due to the heating of the lower ionosphere by electromagnetic pulses generated by lightning discharges.Optical and search coil magnetometer data were obtained from the SPRITES'96 campaign carried out at Yucca Ridge Field Station, Colorado in July 1996. We have presented clear evidence for the excitation of ULF transients with their dominant power at 1-2 Hz by strong lightning discharges producing elves and sprites without preceding elves and the case of sprites with preceding elves. In the former case, damped quasi-sinusoidal oscillations commence impulsively at the onset of sprites, while in the latter case quasi-sinusoidal wavelets with a duration of 〜3 s are excited, and elves and sprites occur within each wavelet. It is lucky that these ULF transients are due to the nonlinear excitation of the ionospheric Alfven resonator by strong lightning discharge.

在科罗拉多州尤卡岭站（北纬40゜40'，西经104゜59'）使用多通道高速光度计和图像增强CCD相机对雷暴上方高空的光学现象进行了观测。新的测量结果表明，在精灵出现后不久，低电离层75-105公里高度处就会出现持续时间小于1毫秒、水平范围约为100-300公里的漫射闪光。这里我们将这些事件指定为“精灵”，以区别于“红色精灵”。这一发现与闪电放电产生的电磁脉冲加热下层电离层而产生漫射光学发射是一致的。光学和搜索线圈磁力计数据是从 1996 年 7 月在科罗拉多州尤卡岭场站进行的 SPRITES'96 活动中获得的。我们已经提供了明确的证据，证明强闪电放电在 1-2 Hz 处激发了 ULF 瞬变，其主导功率为 1-2 Hz 产生没有前面的精灵的精灵和精灵以及有前面的精灵的精灵的情况。在前一种情况下，阻尼准正弦振荡在精灵开始时脉冲地开始，而在后一种情况下，持续时间约为 3 s 的准正弦小波被激发，并且每个小波内都会出现精灵和精灵。幸运的是，这些 ULF 瞬变是由于强闪电放电对电离层阿尔文谐振器的非线性激励造成的。