Anomalously strong vertical magnetic fields from distant ELF/VLF sources
Anomalously strong vertical magnetic fields from distant ELF/VLF sources
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DOI：
10.1002/2015ja021141
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发表时间：
2015-07
期刊：
影响因子：
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通讯作者：
I. Silber;C. Price;E. Galanti;A. Shuval
中科院分区：
文献类型：
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作者：
I. Silber;C. Price;E. Galanti;A. Shuval
在地球电离层波导中有许多极低频（VLF-3-30 kHz）和极低频（ELF-3-3000 Hz）辐射源（例如，闪电和极低频/甚低频通信发射机）。在距离这些源数千公里的地方，极低频/甚低频交流磁场的垂直分量预计非常微弱，比水平磁场分量低几个数量级。然而，在以色列的测量表明，在极低频和甚低频波段都有一个相对较强的垂直磁分量，其数量级与水平分量相同。我们的测量结果表明，真实的地球电离层波导通常可能与模型计算中使用的理论波导非常不同。此外，我们的研究结果意味着，仅使用水平分量进行测向或绝对磁场强度可能会导致误差，因为通常磁场能量的很大一部分隐藏在垂直分量中。
There are many sources of very low frequency (VLF—3–30 kHz) and extremely low frequency (ELF—3–3000 Hz) radiation in the Earth‐ionosphere waveguide (e.g., lightning and ELF/VLF communication transmitters). At distances of thousands of kilometers from these sources, the vertical component of the ELF/VLF AC magnetic fields is expected to be very weak and several orders of magnitude lower than the horizontal magnetic components. However, measurements in Israel show a relatively strong vertical magnetic component in both the ELF and VLF bands, at the same order of magnitude as the horizontal components. Our measurements suggest that the real Earth‐ionosphere waveguide might often be very different from the theoretical waveguide used in model calculations. In addition, our results imply that using only the horizontal components for direction finding or the absolute magnetic field strength may result in errors, since often a significant fraction of the magnetic field energy hides in the vertical component.