The Characteristic and Current Model of Radiation Impulse in Lightning Initial Preliminary Breakdown Process
-
摘要: 利用2012年青海大通地区高精度闪电三维辐射源定位结果和宽带电场脉冲波形同步数据,基于3种改进的传输线模型和粒子群优化算法,拟合发生在不同距离上不同类型闪电初始预击穿过程的双极性脉冲波形结构,反演初始流光通道内电流波形和特征参数,对比分析3种模型对初始预击穿过程和梯级先导双极性脉冲波形的拟合效果,统计分析4类闪电初始预击穿脉冲的物理特征。结果表明:3种改进的传输线模型均能较好地拟合出双极性脉冲结构,且MTLE模型更合理。负地闪的初始预击穿过程和梯级先导过程呈现出相同的传输特征,即均以梯级形式发展,且拟合物理参量也较为接近。初始流光向上的路径长度大于初始流光向下的路径长度,初始流光向上击穿进入上部正电荷区的路径上中和的总电荷量和总垂直偶极矩远大于初始流光向下的路径上中和的总电荷量和总垂直偶极矩。Abstract: Physical characteristics of the initial breakdown pulse has been studied widely, but the exact three-dimensional position of the initial breakdown pulse and physical characteristics of the maximum amplitude initial breakdown pulse are not understood deeply yet. Based on three improved transmission line models and particle swarm optimization algorithm, the bipolar pulse of initial preliminary breakdown process in different types of lightning at different distances is fitted by using high-precision lightning three-dimensional radiation source localization results and synchronization data of wideband electric field pulse waveform at Datong of Qinghai. The radiation field component is modified and the current waveform of initial streamer channel and characteristic parameters are derived. The fitting effect of three models on the bipolar pulse waveform of the initial preliminary breakdown process and step leader process are comparatively analyzed, and the physical feature of the initial breakdown pulse are statistically analyzed. At the same time, the bipolar pulse propagation mechanism and physical characteristics of the lightning initial pre-breakdown process are further studied.All three models can reasonably fit the measured bipolar waveforms. and it may be more reasonable that the current in the channel exponentially decays with height. The leader process and the initial preliminary breakdown process of the negative cloud-to-ground flash show cascaded developing, and both parameters using MTLE model fitting is close, indicating their transmission features are similar. The total amount of charge, total vertical dipole moment and the path length of the initial streamer upward propagating to positive charge region are larger than that of the initial streamer downward propagating to positive charge region. It may be related with the distance between the positive and negative charge region. When fitting the bipolar pulse waveform with three improved transmission line models, no model is constantly better than the other models, and it depends on specific analysis of the pulse structure. It should be noted that some of the initial pre-puncturing process bipolar pulse sometimes superimposed on the high frequency pulse, which may affect the fitting effect, but these pulses are considered inevitable product of the lightning discharge process. The presence of these pulses cannot be ignored when fitting. The wide-band electric field pulse waveform produced by lightning discharge is also distorted by the influence of environmental factors (mountains, trees, etc.) during the transmission process, which may cause the fitting effect of the pulse rising edge and the pulse end period not ideal, and therefore, synchronized electric field pulse waveform data in other observation stations can be selected for comparison and confirmation.
-
图 4 3种模型下IBP-1观测、拟合电场变化及分量场对比
(a)MTLL模型电场变化,(b)MTLE模型电场变化,(c)MTLK模型电场变化,(d)MTLL模型分量场,(e)MTLE模型分量场,(f)MTLK模型分量场
Fig. 4 The measured, fitted electric field changes and component field of IBP-1 under three models
(a)the electric field change under MTLL model, (b)the electric field change under MTLE model, (c)the electric field change under MTLK model, (d)the component field under MTLL model, (e)the component field under MTLE model, (f)the component field under MTLK model
图 6 3种模型下IBP-2观测、拟合电场变化及分量场对比
(a)MTLL模型电场变化,(b)MTLE模型电场变化,(c)MTLK模型电场变化,(d)MTLL模型分量场,(e)MTLE模型分量场,(f)MTLK模型分量场
Fig. 6 The measured, fitted electric field changes and component field of IBP-2 under three models
(a)the electric field change under MTLL model, (b)the electric field change under MTLE model, (c)the electric field change under MTLK model, (d)the component field under MTLL model, (e)the component field under MTLE model, (f)the component field under MTLK model
表 1 53个双极性脉冲拟合统计的结果
Table 1 Fitted results of 53 bipolar pulses
放电过程(脉冲数) MTLL模型 MLTE模型 MTLK模型 平均确定系数 拟合最佳脉冲数 确定系数 拟合最佳脉冲数 确定系数 拟合最佳脉冲数 确定系数 负云闪初始预击穿过程(6个) 1 0.893 3 0.899 2 0.898 0.897 正云闪初始预击穿过程(23个) 5 0.881 12 0.881 6 0.880 0.881 初始向下负地闪初始预击穿过程(7个) 2 0.894 4 0.895 1 0.891 0.892 初始向上负地闪初始预击穿过程(8个) 2 0.877 4 0.875 2 0.877 0.877 初始向下发展负地闪梯级先导(9个) 2 0.856 4 0.857 3 0.855 0.854 总双极性脉冲(53个) 12 0.879 27 0.879 14 0.8788 0.879 表 2 初始向下负地闪20120724163958初始预击穿过程和梯级先导过程MTLE模型拟合结果
Table 2 Physical parameters of step leader pulse of the negative cloud-to-ground flash 20120724163958 whose initial streamer developing downward in MTLE model
物理参数 初始预击穿过程 梯级先导过程 范围 平均值 范围 平均值 t1/μs 0.7~0.8 0.75 0.3~0.72 0.47 (t1-t2)/μs 1.25~7.45 4.55 1.2~4.5 2.76 v/(108 m·s-1) 1.18~1.3 1.24 1.28~1.5 1.35 A/kA 15.32~78.23 40.65 12.10~60.49 32.99 Q/C 0.123~0.629 0.363 0.09~0.41 0.222 P/(C·m) 10.19~108.39 47.91 8.39~44.36 23.23 表 3 4类闪电初始预击穿过程MTLE模型拟合结果
Table 3 Physical parameters of initial breakdown pulse of four different types of flashes in MTLE model
放电过程 初始流光向上或向下进入正电荷区路径长度/m 起始脉冲簇中和电荷总量/C 起始脉冲簇总垂直偶极矩/(C·m) 负云闪初始预击穿过程 947.55(向下) 1.944 227.436 正云闪初始预击穿过程 3174.14(向上) 13.179 -4136.55 初始向下负地闪初始预击穿过程 750.47(向下) 1.491 335.342 初始向上负地闪初始预击穿过程 1389.24(向上) 2.744 -390.344 -
[1] Kitagawa N, Brook M.A comparison of intracloud and cloud-to-ground lightning discharges.Journal of Geophysical Research:Atmospheres, 1960, 65(4):1189-1201. doi: 10.1029/JZ065i004p01189 [2] Krider E P, Radda G J, Noggle R C.Regular radiation field pulses produced by intracloud lightning discharges.J Geophys Res, 1975, 80(27):3801-3804. doi: 10.1029/JC080i027p03801 [3] Weidman C D, Krider E P.The radiation field wave forms produced by intracloud lightning discharge processes.Journal of Geophysical Research:Oceans, 1979, 84(C6):3159-3164. doi: 10.1029/JC084iC06p03159 [4] William B, Uman M A, Rustan P L.Electric fields preceding cloud-to-ground lightning flashes.J Geophys Res, 1982, 87(C7):4883-4902. doi: 10.1029/JC087iC07p04883 [5] Ushio T O, Kawasaki Z I, Matsu-Ura K, et al.Electric fields of initial breakdown in positive ground flash.J Geophys Res, 1998, 103(D12):14135-14140. doi: 10.1029/97JD01975 [6] Gomes C, Cooray V, Jayaratne C.Comparison of preliminary breakdown pulses observed in Sweden and in Sri Lanka.Journal of Atmospheric and Solar-Terrestrial Physics, 1998, 60(10):975-979. doi: 10.1016/S1364-6826(98)00007-8 [7] Rakov V A, Uman M A.Lightning:Physics and Effects.Cambridge U K:Cambridge Univ Press, 2003. [8] Watson S S, Marshall T C.Current propagation model for a narrow bipolar pulse.Geophys Res Lett, 2007, 34(4):344-356. [9] Rison W, Krehbiel P R, Stock M G, et al.Observations of narrow bipolar events reveal how lightning is initiated in thunderstorms.Nature Communications, 2016, 7:10721. doi: 10.1038/ncomms10721 [10] Shao X M, Heavner M.On the VLF/LF Radiation Pulse Shapes at the Initial Milliseconds of Lightning Discharges//International Zurich Symposium on Electromagnetic Compatibility, 2006.Emc-Zurich.IEEE Xplore, 2006:402-404. [11] Pasko V P.Electrostatic modeling of intracloud stepped leader electric fields and mechanisms of terrestrial gamma ray flashes.Geophys Res Lett, 2014, 41(1):179-185. doi: 10.1002/2013GL058983 [12] Karunarathne S, Marshall T C, Stolzenburg M, et al.Modeling initial breakdown pulses of CG lightning flashes.Journal of Geophysical Research:Atmospheres, 2014, 119(14):9003-9019. doi: 10.1002/2014JD021553 [13] Nag A, Rakov V A.Electric field pulse trains occurring prior to the first stroke in negative cloud-to-ground lightning.IEEE Transactions on Electromagnetic Compatibility, 2009, 51(1):147-150. doi: 10.1109/TEMC.2008.2005488 [14] 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 [15] 张义军, 周秀骥.雷电研究的回顾和进展.应用气象学报, 2006, 17(6):829-834. doi: 10.11898/1001-7313.20060619 [16] 张义军, Krehbiel P R, 刘欣生, 等.闪电放电通道的三维结构特征.高原气象, 2003, 22(3):217-220. http://www.cnki.com.cn/Article/CJFDTOTAL-GYQX200303002.htm [17] 张义军, 徐良韬, 郑栋, 等.强风暴中反极性电荷结构研究进展.应用气象学报, 2014, 25(5):513-526. doi: 10.11898/1001-7313.20140501 [18] 张义军, 孟青, 吕伟涛, 等.云下部正电荷区与负地闪预击穿过程.气象学报, 2008, 66(2):274-282. doi: 10.11676/qxxb2008.026 [19] 刘恒毅, 董万胜, 徐良韬, 等.闪电起始过程时空特征的宽带干涉仪三维观测.应用气象学报, 2016, 27(1):16-24. doi: 10.11898/1001-7313.20160102 [20] Wu B, Zhang G, Wen J, et al.Correlation analysis between initial preliminary breakdown process, the characteristic of radiation pulse, and the charge structure on the Qinghai-Tibetan Plateau.Journal of Geophysical Research:Atmospheres, 2016, 121(20):12434-12459. doi: 10.1002/2016JD025281 [21] 张义军, 言穆弘.闪电先导静电场波形理论分析.应用气象学报, 1993, 12(2):185-191. http://qikan.camscma.cn/jams/ch/reader/view_abstract.aspx?file_no=19930233&flag=1 [22] 任晓毓, 张义军, 吕伟涛, 等.雷击建筑物的先导连接过程模拟.应用气象学报, 2010, 21(4):450-457. doi: 10.11898/1001-7313.20100408 [23] 廖义慧, 吕伟涛, 齐奇, 等.基于闪电先导随机模式对不同连接形态的模拟.应用气象学报, 2016, 27(3):361-369. doi: 10.11898/1001-7313.20160311 [24] 任晓毓, 张义军, 吕伟涛, 等.闪电先导随机模式的建立与应用.应用气象学报, 2011, 22(2):194-202. doi: 10.11898/1001-7313.20110208 [25] 李婵, 张阳, 吕伟涛, 等.地闪不规则先导的多尺度熵特征.应用气象学报, 2014, 25(3):347-353. doi: 10.11898/1001-7313.20140311 [26] 张广庶, 郄秀书, 王怀斌, 等.闪电多参量同步高速即时记录系统.高原气象, 2003, 22(3):301-305. http://www.cnki.com.cn/Article/CJFDTOTAL-GYQX200303015.htm [27] 张广庶, 王彦辉, 郄秀书, 等.基于时差法三维定位系统对闪电放电过程的观测研究.中国科学:地球科学, 2010, 40(4):523-534. http://www.cnki.com.cn/Article/CJFDTOTAL-JDXK201004014.htm [28] 李亚珺, 张广庶, 王彦辉, 等.闪电宽带电场三维定位及其回波特征.高原气象, 2009, 28(6):1453-1462. http://www.cnki.com.cn/Article/CJFDTOTAL-GYQX200906026.htm [29] Stolzenburg M, Marshall T C, Karunarathne S, et al.Luminosity of initial breakdown in lightning.Journal of Geophysical Research:Atmospheres, 2013, 118(7):2918-2937. doi: 10.1002/jgrd.50276 [30] Uman M A, Mclain D K, Krider E P.The electromagnetic radiation from a finite antenna.American Journal of Physics, 1975, 43(1):33-38. doi: 10.1119/1.10027 [31] Rakov V A, Dulzon A A.Calculated Electromagnetic Fields of Lightning Return Stroke, Tekh.Elektrodinam, 1987, 1:87-89. [32] Nucci C A, Mazzetti C, Rachidi F, et al.On Lightning Return Stroke Models for LEMP Calculations//19th International Conference on Lightning Protection.1988. [33] Kumaraswamy P.A generalized probability density function for double-bounded random processes.J Hydrol, 1980, 46(1-2):79-88. doi: 10.1016/0022-1694(80)90036-0 [34] Vine D M L, Willett J C.Comment on the transmission-line model for computing radiation from lightning.Journal of Geophysical Research:Atmospheres, 1992, 97(D2):2601-2610. doi: 10.1029/91JD02817 [35] Shao X M, Jacobson A R, Fitzgerald T J.Radio frequency radiation beam pattern of lightning return strokes:A revisit to theoretical analysis.Journal of Geophysical Research:Atmospheres, 2004, 109(D19):2083-2089. doi: 10.1029/2004JD004612/full [36] Taylor W L.Radiation field characteristics of lightning discharges in the band 1 kc/s to 100 kc/s.Journal of Research of the National Bureau of Standards, 1963, 67D(5):539. [37] Joseph P, Uman M A, Childers D G.The RF spectra of first and subsequent lightning return strokes in the 1-to 200-km range.Radio Science, 1981, 15(6):1089-1094. http://ieeexplore.ieee.org/document/7768379/ [38] Weidman C D, Krider E P, Uman M A.Lightning amplitude spectra in the interval from 100 kHz to 20 MHz.Geophys Res Lett, 1981, 8(8):931-934. doi: 10.1029/GL008i008p00931 [39] Sonnadara U, Cooray V, Fernando M.The lightning radiation field spectra of cloud flashes in the interval from 20 kHz to 20 MHz.IEEE Transactions on Electromagnetic Compatibility, 2006, 48(1):234-239. doi: 10.1109/TEMC.2006.870692 [40] Kennedy J, Eberhart R.Particle Swarm Optimization//Proceedings of IEEE International Conference on Neural Networks.IEEE Xplore, 1995.