Characteristics of Low‐Frequency Pulses Associated With Downward Terrestrial Gamma‐Ray Flashes
Characteristics of Low‐Frequency Pulses Associated With Downward Terrestrial Gamma‐Ray Flashes
复制标题
与向下地面伽马射线闪光相关的低频脉冲的特征
DOI：
10.1029/2021gl097348
复制
发表时间：
2022
影响因子：
5.2
通讯作者：
Tsuchiya H.
中科院分区：
文献类型：
--
作者：
Wada Y.;Morimoto T.;Nakamura Y.;Wu T.;Enoto T.;Nakazawa K.;Ushio T.;Yuasa T.;Tsuchiya H.
由于低电荷中心的云结构，日本的冬季雷暴被认为是观察高能大气现象的理想目标。在日本的四个冬季期间(2016年10月至2020年3月)，伽马射线和宽带低频(LF：0.8-500 GHz)监视器探测到了7次向下的地面伽马射线闪光(TGFs)。所有探测到的TGFs都发生在闪电的初始阶段。根据低频观测，本研究中的7个向下的TGFs可分为两种类型：高能双极型和小双极型。其中三个是能量双极事件，与峰值电流大于100kA的负回击产生的高峰值电流LF脉冲重合。其他是小的双极事件，紧随其后的是具有中等峰值电流的负双极低频脉冲。四个小双极事件中有三个是多脉冲TGFs，而本研究中所有的能量双极事件都是单脉冲TGFs。
Winter thunderstorms in Japan have been recognized as an ideal target to observe high‐energy atmospheric phenomena thanks to low‐charge‐center cloud structures. During four winter seasons in Japan (from 2016 October to 2020 March), seven downward terrestrial gamma‐ray flashes (TGFs) were detected by gamma‐ray and broadband low‐frequency (LF: 0.8–500 kHz) monitors. All the detected TGFs took place at the initial stage of lightning flashes. Based on the LF observation, the seven downward TGFs in the present study can be classified into two types: energetic‐bipolar and small‐bipolar types. Three of them are energetic‐bipolar events, coincident with a high peak‐current LF pulse that originates from a negative return stroke with a peak current larger than 100 kA. The others are small‐bipolar events, followed by a negative bipolar LF pulse with a moderate peak current. Three of the four small‐bipolar events are multi‐pulse TGFs, while all of the energetic‐bipolar events in this study are single‐pulse TGFs.