| NBE和IBP始发的闪电初始特征 |
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| 引用本文： | 张骁,张阳,张义军,郑栋,吕伟涛.NBE和IBP始发的闪电初始特征[J].应用气象学报,2018,29(3):364-373. |
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| 作者姓名： | 张骁 张阳 张义军 郑栋 吕伟涛 |
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| 作者单位： | 1.中国气象科学研究院灾害天气国家重点实验室, 北京 100081 |
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| 基金项目： | 国家自然科学基金项目（41775009，91537209），中国气象科学研究院基本科研业务费专项（2015Z006） |
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| 摘 要： | 基于闪电低频电场探测阵列（LFEDA）所获得的全闪三维定位数据，研究了2015年8月15日14:30—16:10广州一次雷暴过程中具有明显始发脉冲的闪电初始放电特征及放电规律。结果表明:212例近距离云闪和地闪中，32例闪电由窄偶极性放电事件（NBE）始发，占15%；180例闪电由初始击穿脉冲（定义初始击穿脉冲簇的首个脉冲为FIBP）始发，占85%。作为始发的窄偶极性放电事件（INBE），其相对孤立且具有较大的相对幅度，INBE与后续闪电的第1个脉冲的时间间隔为7 ms，幅度比为3.5，远大于FIBP相对应的时间间隔0.6 ms和幅度比0.8，INBE后多跟随传统的IBP脉冲。多数正极性INBE与FIBP对应初始向上发展的闪电，而负极性对应初始向下发展的闪电。INBE始发闪电前15 ms的平均发展速度随始发高度的增大而减小，快于FIBP，这与INBE具有更快的速度相关。估计的INBE速度为4.7×107 m·s-1，FIBP速度为1.5×107 m·s-1，两者速度差异也体现在脉冲上升时间方面，INBE具有更快的上升沿。
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| 关 键 词： | NBE IBP 闪电始发 |
| 收稿时间： | 2017/11/22 0:00:00 |
| 修稿时间： | 2018/1/29 0:00:00 |
Initial Stage of Lightning Discharges Initiated by NBE and IBP |
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| Zhang Xiao,Zhang Yang,Zhang Yijun,Zheng Dong and L&#; Weitao.Initial Stage of Lightning Discharges Initiated by NBE and IBP[J].Quarterly Journal of Applied Meteorology,2018,29(3):364-373. |
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| Authors: | Zhang Xiao Zhang Yang Zhang Yijun Zheng Dong and L&#; Weitao |
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| Institution: | 1.State Key Laboratory of Severe Weather, Chinese Academy of Meteorological Sciences, Beijing 1000812.Chengdu University of Information Technology, Chengdu 610103 |
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| Abstract: | Lightning initial stage is an important and fundamental physical process. How lightning initiates is a hot topics in the research of lightning physics. Initial breakdown is observed by many researchers, and the first pulse of IBP is regarded as the starting marker of intracloud lightning or cloud-to-ground lighting. Lightning discharge characteristics and laws during initial stage in a thunderstorm progress are researched based on Low-frequency E-field Detection Array (LFEDA). In 212 intracloud lightnings and cloud-to-ground lightnings of short range, 32 lightnings are initiated by NBE, accounting for 15%, and 180 lightnings are initiated by IBP, accounting for 85%. As an initial NBE (INBE), it is more isolated and larger than the first pulse of initial IBP (FIBP). The average time interval from INBE to subsequent first pulse is 7 ms, with a mid-value of 3.9 ms. The amplitude ratio between INBE and the subsequent pulse is 3.5. The above values are larger than those of FIBP with the corresponding values of 0.6 ms, 0.2 ms and 0.8. Most of the positive INBE and FIBP corresponds to an upward discharge in the initial stage while negative correspond to a downward one. The average height of INBE is 9.9 km, which is less than isolated NBE of 13.6 km. There is also a sensible difference in discharge height between isolated positive NBE and the negative one. The isolated negative NBE is much higher than the positive one. It may occur between upper positive charge region and shielding layer, which is related to the middle and upper atmosphere discharge. The average height of FIBP is 8.1 km. There are no obvious differences in discharge height between INBE and FIBP. The average speed during the first 15 ms of the lightning initiated by NBE is 3.1×105 m·s-1, with a mid-value of 3.0×105 m·s-1, which decreases with the initial altitude. The maximum and minimum average speed is 7×105 m·s-1 and 1.2×105 m·s-1, respectively. To better reveal the difference in INBE and FIBP, an estimated velocity is calculated based on the hypothesis of low-frequency pulse corresponding to a channel extending. The estimated speed of INBE is 4.7×107 m·s-1, which is faster than FIBP with a velocity of 1.5×107 m·s-1. The shorter rising time for INBE also indicates a faster velocity. There are no apparent differences in rising time, half-peak width and pulse width for INBE, NBE in process and isolated NBE. It is difficult to distinguish INBE from other NBE by pulse property. |
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| Keywords: | NBE IBP lightning initiation |
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