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和田 有希*; 榎戸 輝揚*; 中村 佳敬*; 森本 健志*; 佐藤 光輝*; 牛尾 知雄*; 中澤 知洋*; 湯浅 孝行*; 米徳 大輔*; 澤野 達也*; et al.
Journal of Geophysical Research; Atmospheres, 125(4), p.e2019JD031730_1 - e2019JD031730_11, 2020/02
被引用回数：21 パーセンタイル：80.58(Meteorology & Atmospheric Sciences)During 2017-2018 winter operation of the Gamma-Ray Observation of Winter Thunderclouds experiment in Japan, two downward terrestrial gamma-ray flashes (TGFs) that triggered atmospheric photonuclear reactions were detected. They took place during winter thunderstorms on 5 December 2017 and 9 January 2018 at Kanazawa, Ishikawa Prefecture, Japan. Each event coincided with an intracloud/intercloud discharge, which had a negative-polarity peak current higher than 150 kA. Their radio waveforms in the low-frequency band are categorized as a distinct lightning type called energetic in-cloud pulse (EIP). Negative-polarity EIPs have been previously suggested to be highly associated with downward TGFs, and the present observations provide evidence of the correlation between them for the first time. Furthermore, both of the downward TGFs followed gamma-ray glows, minute-lasting high-energy emissions from thunderclouds. It is suggested that the negative EIPs took place with downward propagating negative leaders or upward positive ones developed in highly electrified regions responsible for the gamma-ray glows.
和田 有希*; 榎戸 輝揚*; 中村 佳敬*; 古田 禄大; 湯浅 孝行*; 中澤 知洋*; 森本 健志*; 佐藤 光輝*; 松元 崇弘*; 米徳 大輔*; et al.
Communications Physics (Internet), 2(1), p.67_1 - 67_9, 2019/06
被引用回数：49 パーセンタイル：93.08(Physics, Multidisciplinary)Two types of high-energy events have been detected from thunderstorms. One is "terrestrial gamma-ray flashes" (TGFs), sub-millisecond emissions coinciding with lightning discharges. The other is minute-lasting "gamma-ray glows". Although both phenomena are thought to originate from relativistic runaway electron avalanches in strong electric fields, the connection between them is not well understood. Here we report unequivocal simultaneous detection of a gamma-ray glow termination and a downward TGF, observed from the ground. During a winter thunderstorm in Japan on 9 January 2018, our detectors caught a gamma-ray glow, which moved for 
100 s with ambient wind, and then abruptly ceased with a lightning discharge. Simultaneously, the detectors observed photonuclear reactions triggered by a downward TGF, whose radio pulse was located within 
1 km from where the glow ceased. It is suggested that the highly-electrified region producing the glow was related to the initiation of the downward TGF.
