Publication Date:
2018-06-09
Description:
An on-ground observation program for high-energy atmospheric phenomena in winter thunderstorms along the Japan Sea has been performed via measurements of gamma ray radiation, atmospheric electric field, and low-frequency radio band. On 11 February 2017, the radiation detectors recorded gamma ray emission lasting for 75 s, and then abruptly terminated with a nearby lightning discharge. The gamma ray spectrum extended up to 20 MeV and was reproduced by a cutoff power law model with a photon index of 1.36 +0.03 −0.04 , being consistent with Bremsstrahlung radiation from a thundercloud (known as a gamma-ray glow or a thunderstorm ground enhancement). The low-frequency radio monitors, installed ∼50 km away from the gamma ray observation site recorded leader development of an intracloud/intercloud discharge spreading over ∼60 km area with a ∼300-ms duration. The timing of the gamma ray termination coincided with the moment when the leader development of the intracloud/intercloud discharge passed 0.7 km horizontally away from the radiation monitors. The intracloud/intercloud discharge started ∼15 km away from the gamma ray observation site. Therefore, the glow was terminated by the leader development, while it did not trigger the lightning discharge in the present case. ©2018. The Authors.
Print ISSN:
0094-8276
Electronic ISSN:
1944-8007
Topics:
Geosciences
,
Physics