Comparative Analysis on Characteristics and Mechanism for Two Types of M-component in Triggered Lightning
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摘要: 综合分析人工触发闪电通道底部的电流数据和电场变化数据,获得对M分量的新认识。M分量的幅值、上升时间、半峰值宽度、转移电荷量的几何平均值分别为301 A,341 μs,662 μs,0.207 C。但发现有两种类型的M分量,其统计特征和分布特征均体现了较大差别。第1类M分量幅度较小,半峰值宽度较大,上升时间较长;第2类M分量则幅度较大,半峰值宽度较小,上升时间较短,两类M分量和回击的时间间隔有较大差异。采用双波放电模型,通过设定不同入射电流波速度和反射电流波速度,对两类M分量进行从电流到电场的反演。结果表明:当模拟电场和测量电场比较一致时,第1类M分量的入射速度和反射速度的比值大于第2类M分量,即两类M分量的放电机制具有一定差异。Abstract: Parameters such as amplitude, rise time, half-peak width and charge transfer is obtained by analyzing channel base current data from triggered lightning, which is acquired by GCOELD (Guangdong Comprehensive Observation Experiment of Lightning Discharge) during 2008 and 2013. Geometric mean value of amplitude, rise time, half-peak width and charge transfer from 31 samples are 301 A, 341 μs, 662 μs and 0.207 C, among which geometric mean value of amplitude is close to the result from Shandong Articicially Triggering Lightning Experiment, while rise time and half-peak width are close to results in Florida. From the histogram for parameter distribution, M-component is mostly within 400 A, the rise time is lower than 400 μs, the half-peak width is less than 1 ms, and the charge transfer is from 0.1 C to 0.3 C. Whereas, histogram of amplitude, rise time, half-peak width and charge transfer indicates portion of M-component has unusual characteristics. Combined with previous research, it's concluded that M-component can be divided into two types, by amplitude lower/higher than 1 kA. Geometric mean value of amplitude, rise time, half-peak width and charge transfer is analyzed, respectively. Two types of M-component show obvious differences, for instance, the amplitude of Type 2 M-component is almost 10 times the value of Type 1 M-component, while the rise time and half-peak width is approximately quarter of the corresponding parameter for Type 1. In general, Type 2 M-component has higher amplitude, shorter rise time and narrower half-peak width than Type 1. The relationship between M amplitude and the lag between return stroke and M-component for Type 1 and Type 2 are compared, and lags of Type 2 M-components are shorter than 50 ms, shorter than lags of Type 1 M-components as a whole. It possibly indicates that the lower the amplitude of M-component is, the longer the lag is. With M-component two-wave model, the electric field are calculated. By configuring incident wave velocity and reflected wave velocity to various values, it's found that the result is consistent with measured electric field, but the incident velocity is always smaller than reflected velocity for both Type 1 and Type 2. The ratio between incident wave velocity and reflected wave velocity for Type 1 is larger than that of Type 2. Based on analysis for M-component characteristics and M-component classification, two types of M-component may correspond with streamer occurred by breakdown in channel branch into main channel and breakdown within part of the lightning channel, indicating Type 1 M-component has some differences with Type 2 M-component in mechanism.
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表 1 不同地点人工触发闪电M分量基本特征的统计结果
Table 1 Statistical results for M-component characteristics from different experiment sites
表 2 第1类和第2类M分量特征比较
Table 2 Comparison of two types of M-component
特征量 第1类M分量 第2类M分量 幅值/A 191 2005 上升时间/μs 452 105 半峰值宽度/μs 866 216 转移电荷量/C 0.176 0.407 -
[1] 张义军, 孟青, 马明, 等.闪电探测技术发展和资料应用.应用气象学报, 2006, 17(5):611-620. doi: 10.11898/1001-7313.20060504 [2] 张阳, 张义军, 孟青, 等.北京地区正地闪时间分布及波形特征.应用气象学报, 2010, 21(4):442-449. doi: 10.11898/1001-7313.20100407 [3] Fisher R J, Schnetzer G H, Thottappillil R, et al.Parameters of triggered-lightning flashes in Florida and Alabama. J Geophys Res, 1993, 98:22887-22908. doi: 10.1029/93JD02293 [4] Thottappillil R, Goldberg J, Rakov V, et al.Properties of M components from current measured at triggered lightning channel base. J Geophys Res, 1995, 100(12):25711-25720. https://www.researchgate.net/publication/252609052_Properties_of_M_components_from_currents_measured_at_triggered_lightning_channel_base [5] Malan D J, Collens H.Progressive lightning Ⅲ-The fine structure of return lightning strokes. Proc R Soc London A, 1937, 162:175-203. doi: 10.1098/rspa.1937.0175 [6] Rakov V A, Thottappillil R, Uman M A, et al.Mechanism of the lightning M component. J Geophys Res, 1995, 100:25701-25710. doi: 10.1029/95JD01924 [7] Rakov V A, David E C, Keith J R, et al.M-component mode of charge transfer to ground in lightning discharges. J Geophys Res, 2001, 106:22817-22831. doi: 10.1029/2000JD000243 [8] Leandro Z S C, Marccelo M F S, Osmar P, et al.Waveshapes of continuing currents and properties of M-components in natural negative cloud-to-ground lightning from high-speed video observations. Atmos Res, 2007, 84:302-310. doi: 10.1016/j.atmosres.2006.09.002 [9] 赵阳, 郄秀书, 陈明理, 等.人工触发闪电中的M分量特征.高原气象, 2011, 30(2):508-517. http://www.cnki.com.cn/Article/CJFDTOTAL-GYQX201102028.htm [10] 周方聪, 张义军, 吕伟涛, 等.人工触发闪电连续电流过程与M分量特征.应用气象学报, 2014, 25(3):330-338. doi: 10.11898/1001-7313.20140309 [11] Qie X S, Jiang R B, Wang C X, et al.Simultaneously measured current, luminosity, and electric field pulses in a rocket-triggered lightning flash. J Geophys Res, 2011, 116:D10102(1-11). [12] 肖桐, 张阳, 吕伟涛, 等.人工触发闪电M分量的电流与电磁场特征.应用气象学报, 2013, 24(4):446-454. doi: 10.11898/1001-7313.20130407 [13] Rakov V A, Uman M A, Wang D, et al.New insights into lightning processes gained from triggered-lightning experiments in Florida and Alabama. J Geophys Res, 1998, 103:14117-14130. doi: 10.1029/97JD02149 [14] Megumu M, Takatoshi S.Charcterization of Current Pulses Superimposed on the Continuous Current in Upward Lightning Initiated from Tall Objects and in Rocket Triggered Lightning.28th International Conference on Lightning Protection, 2006. [15] 蒋如斌, 郄秀书, 王彩霞, 等.峰值电流达几千安量级的闪电M分量放电特征及机理探讨.物理学报, 2011, 60:079201. http://www.cnki.com.cn/Article/CJFDTOTAL-WLXB201107130.htm [16] 李俊, 张义军, 吕伟涛, 等.一次多回击自然闪电的高速摄像观测.应用气象学报, 2008, 19(4):401-411. doi: 10.11898/1001-7313.20080403 [17] 张义军, 杨少杰, 吕伟涛, 等.2006—2011年广州人工触发闪电观测试验和应用.应用气象学报, 2012, 23(5):513-522. doi: 10.11898/1001-7313.20120501 [18] 李俊, 吕伟涛, 张义军, 等.一次多分叉多接地的空中触发闪电过程.应用气象学报, 2010, 21(1):95-100. doi: 10.11898/1001-7313.20100113 [19] Jiang R B, Qie X S, Yang J, et al.Characteristics of M-component in rocket-triggered lightning and a discussion on its mechanism. Radio Science, 2013, 48:1-10. doi: 10.1029/2012RS005074 [20] Rakov V A, Thottappillil R, Uman M A, et al. Electric field pulses in K and M changes of lightning ground flashes. J Geophys Res, 1992, 97:9935-9950. doi: 10.1029/92JD00797 [21] Shao X M, Krehbiel P R, Thomas R J, et al.Radio interferometric observations of cloud-to-ground lightning phenomena in Florida. J Geophys Res, 1995, 100:2749-2783. doi: 10.1029/94JD01943 [22] Chen M L, Shen Y C.Fine Spatial Structures and Associated Electric Field Changes for an M-component Observed with a VHF Broadband Interferometer System.32nd International Conference on Lightning Protection, 2014.