Unifying VLF Transmitter and Sferic Modeling Efforts Via Tomography
Unifying VLF Transmitter and Sferic Modeling Efforts Via Tomography
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DOI：
10.1029/2023ja031989
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发表时间：
2023-11
期刊：
影响因子：
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通讯作者：
D. Richardson;M. Cohen
中科院分区：
文献类型：
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作者：
D. Richardson;M. Cohen
我们展示了一种利用甚低频（VLF，3 - 30 kHz）发射机和闪电发射的测量来生成3D较低电子密度图的方法，并将其应用于多种地球物理扰动。D区低电离层（60 - 90 km）形成了地球电离层波导的上边界，它允许甚低频无线电波传播到全球范围。在许多先前的研究中，这些信号的测量被用来推断D区域内的路径平均电子密度分布。从历史上看，研究人员一直专注于VLF发射机或闪电无线电大气（sferics）的测量。在这项工作中，我们建立在最近发表的方法，并提出了一种方法，通过断层扫描统一这两种方法。层析反演的输出产生了美国和墨西哥湾大部分地区的电子密度图。为了说明这种统一方法的好处，白天和夜间地图之间的sferic-only模型和这里建议的新方法进行了比较。我们应用该模型来描述两个地球物理扰动：太阳耀斑和低电离层的变化与雷暴。
We demonstrate a methodology for utilizing measurements from very low frequency (VLF, 3−30 kHz) transmitters and lightning emissions to produce 3D lower electron density maps, and apply it to multiple geophysical disturbances. The D‐region lower ionosphere (60−90 km) forms the upper boundary of the Earth‐ionosphere waveguide which allows VLF radio waves to propagate to global distances. Measurements of these signals have, in many prior studies, been used to infer path‐average electron density profiles within the D region. Historically, researchers have focused on either measurements of VLF transmitters or radio atmospherics (sferics) from lightning. In this work, we build on recently published methods for each and present a method to unify the two approaches via tomography. The output of the tomographic inversion produces maps of electron density over a large portion of the United States and Gulf of Mexico. To illustrate the benefits of this unified approach, daytime and nighttime maps are compared between a sferic‐only model and the new approach suggested here. We apply the model to characterize two geophysical disturbances: solar flares and lower ionospheric changes associated with thunderstorms.