An Advanced Model of Lightning M‐Component
An Advanced Model of Lightning M‐Component
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DOI：
10.1029/2018jd029604
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发表时间：
2019-02
期刊：
影响因子：
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通讯作者：
M. D. Tran;V. Rakov
中科院分区：
文献类型：
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作者：
M. D. Tran;V. Rakov
已经开发出一种先进的闪电 M 分量非线性和非均匀分布电路 (RLCG) 模型。该模型考虑了 M 组件通道的串联电阻 R 由于瞬态电流的加热及其随后的冷却而变化、由于背景连续电流导致的沿通道的纵向电压降、通道电晕鞘中的欧姆损耗（由并联电导 G 表示）以及通道的串联电感 L 和并联电容 C 随离地高度的变化。该模型针对通道基电流和使用火箭线技术触发的负闪电中的七个 M 分量测量的相应闭合电场进行了测试。对一种 M 成分进行了详细的敏感性分析。发现高度变化的串联电感和并联电容以及云内通道（代表激励源）的长度对计算的电流和场波形的影响相对较小，而通道电晕鞘中的欧姆损耗和沿接地通道的电压降的影响则显着。背景持续电流水平和接地电阻的影响对于 M 场显着，但对于 M 电流则不显着。模型预测的云底以下的总功率和电流分布与观察到的 M 分量光度分布一致，并且与观察到的下行先导/向上返回行程分布有很大不同。我们的模型很好地再现了 M 分量的特征，即电流开始和接近电场峰值之间的时间偏移（对于前导/返回行程序列基本上不存在）。
An advanced nonlinear and nonuniform distributed circuit (RLCG) model of lightning M‐component has been developed. The model accounts for the variation of the series resistance R of M‐component channel due to its heating by the transient current and its subsequent cooling, longitudinal voltage drop along the channel due to the background continuing current, ohmic losses in the channel corona sheath (represented by shunt conductance G), and variation of series inductance L and shunt capacitance C of the channel with height above ground. The model was tested against the channel‐base current and corresponding close electric fields measured for seven M‐components in negative lightning triggered using the rocket‐and‐wire technique. Detailed sensitivity analysis was performed for one M‐component. The influences of height‐varying series inductance and shunt capacitance and the length of in‐cloud channel (representing the excitation source) on the computed current and field waveforms were found to be relatively insignificant, while the influences of ohmic losses in the channel corona sheath and voltage drop along the grounded channel were significant. The effects of background continuing current level and grounding resistance were significant for M‐field, but not for M‐current. Model‐predicted overall power and current profiles below the cloud base are consistent with the observed M‐component luminosity profiles and are drastically different from the observed downward leader/upward return stroke profiles. The characteristic feature of M‐components, the time shift between the current onset and close electric field peak (essentially absent for leader/return stroke sequences), was well reproduced by our model.