Dependency of VHF broad band lightning source mapping on Fourier spectra
Dependency of VHF broad band lightning source mapping on Fourier spectra
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DOI：
10.1029/1999gl010997
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发表时间：
2000-09
影响因子：
5.2
通讯作者：
R. Mardiana;Z. Kawasaki
中科院分区：
文献类型：
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作者：
R. Mardiana;Z. Kawasaki
在VHF宽带干涉仪中，应用傅里叶变换来分析雷电辐射源的整个频率范围。可以通过解析每个频率分量相对于至少三个天线传感器的入射角来确定辐射源的位置，然后通过对所有频率分量的入射角求平均来定位角位置。前人提出的这种算术平均方法有一个缺点，特别是对于云地闪光，即无法很好地映射靠近地面的闪电先导通道的位置。研究发现，宽带脉冲的傅里叶谱幅度随着频率的增加而减小，并且具有低谱幅度的频率分量对闪电映射的贡献较小。为了改进映射，提出了加权平均方法。该方法提供了一种最小化频率分量影响的方法，频率分量对闪电映射的贡献较小。
In the VHF broad band interferometer, the Fourier transform is applied to analyze the whole frequency range of lightning radiation sources. The position of a radiation source can be determined by resolving the incident angle for each frequency component against at least three‐antenna sensors, and then by averaging the incident angles of all frequency components the angular position can be located. This arithmetic‐averaging method as proposed by previous authors has a disadvantage, especially for cloud‐to‐ground flashes, that is positions of lightning leader channels near ground level can not be mapped well. It is found that Fourier spectral amplitudes of broad band pulses decrease with increasing frequency, and frequency components having low spectral amplitudes give less contribution to the lightning mapping. To improve the mapping, a weighted‐averaging method is proposed. The method provides a way to minimize the influence of frequency components, which contribute less to the lightning mapping.