| 基于LWPC和IRI模型的NWC台站信号传播幅度建模分析 |
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| 引用本文： | 易娟,顾旭东,李志鹏,林仁桐,蔡毅徽,陈隆,倪彬彬,乐新安.基于LWPC和IRI模型的NWC台站信号传播幅度建模分析[J].地球物理学报,2019,62(9):3223-3234. |
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| 作者姓名： | 易娟 顾旭东 李志鹏 林仁桐 蔡毅徽 陈隆 倪彬彬 乐新安 |
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| 作者单位： | 1. 武汉大学电子信息学院, 武汉 430072;2. 中国科学院地质与地球物理研究所地球与行星物理重点实验室, 北京 100029;3. 中国科学院比较行星学卓越创新中心, 合肥 230026 |
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| 基金项目： | 国家自然科学基金（41574160，41674163），湖北省自然科学优秀青年基金（2016CFA044），武汉大学985工程学科建设项目，澳门科技大学月球与行星科学实验室和中国科学院月球与深空探测重点实验室伙伴实验室开放课题共同资助. |
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| 摘 要： | 频率为3~30 kHz的甚低频（VLF，Very Low Frequency）电磁波具有波长长、传播距离远的特点，能够沿地面-低电离层波导进行传播，在通信、导航等许多领域都被广泛应用.基于波导模理论的长波传播模型（LWPC，Long-Wavelength Propagation Capability）能够用于计算甚低频波的传播路径及幅度，进而研究耀斑、磁暴、地震等事件对电离层的扰动.本文利用国际电离层参考模型（IRI，International Reference Ionosphere）对LWPC中电子密度和碰撞频率进行改进，并将模拟结果与武汉大学VLF接收机实际观测到的NWC （North West Cape）台站信号幅度进行比较分析，结果表明改进后LWPC模型得到的幅度及变化趋势与实际值更加接近.LWPC模型给出的电子密度与IRI模型得到的电子密度在日间基本一致，但是在夜间存在差异，造成夜间部分区域NWC台站信号幅度的差异性，验证了电离层电子密度对于VLF信号传播具有的重要影响.传播路径上的晨昏变化也可以引起VLF信号幅度分布的突变，在日出和日落时间段内存在明显的过渡区域.基于IRI模型的LWPC，改善了VLF电波传播过程的预测分析效果，提供了一种长波导航通信质量的评估方法.
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| 关 键 词： | NWC甚低频台站信号 长波传播模型 国际参考电离层模型 通讯导航 |
| 收稿时间： | 2019-05-15 |
Modeling and analysis of NWC signal propagation amplitude based on LWPC and IRI models |
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| YI Juan,GU XuDong,LI ZhiPeng,LIN RenTong,CAI YiHui,CHEN Long,NI BinBin,YUE XinAn.Modeling and analysis of NWC signal propagation amplitude based on LWPC and IRI models[J].Chinese Journal of Geophysics,2019,62(9):3223-3234. |
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| Authors: | YI Juan GU XuDong LI ZhiPeng LIN RenTong CAI YiHui CHEN Long NI BinBin YUE XinAn |
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| Institution: | 1. School of Electronic Information, Wuhan University, Wuhan 430072, China;2. Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China;3. Center for Excellence in Comparative Planetology, Chinese Academy of Sciences, Hefei 230026, China |
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| Abstract: | VLF (very low frequency) electromagnetic waves at 3~30 kHz have the characteristics of long wavelength and long propagation distance. They can propagate along the Earth-lower ionosphere waveguide, and are widely used in many fields including communication and navigation. The Long Wavelength Propagation Capability (LWPC) model based on the waveguide mode theory provides a useful tool to evaluate the propagation path and amplitude of VLF waves, which can be analyzed to investigate ionospheric disturbances caused by solar flares, magnetic storms, earthquakes and other extreme events. In this paper, the very simple electron density and collision frequency modules originally embedded in LWPC are updated by the International Reference Ionosphere (IRI) model for simulation improvements. The obtained numerical results are then compared to the observed amplitude of NWC VLF transmitter signals by Wuhan University VLF receiver at the Wuhan station. It is found that the amplitude variations of NWC VLF transmitter signals modeled using the LWPC and IRI models are much closer to the observations, which mainly results from the improved nighttime electron density profile from the IRI model and justifies the importance of electron density of the lower ionosphere to the VLF signal propagation properties. In addition, the dawn-dusk electron density variation on the wave propagation path largely modulates the NWC VLF signal amplitude, and forms an obvious transition region during the sunrise and sunset periods. Therefore, incorporation of the IRI model into LWPC improves quantitative analyses and prediction performance of the propagation processes of VLF transmitter signals, and provides an evaluation method of long wave navigation and communication quality. |
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| Keywords: | NWC very low frequency (VLF) transmitter signals Long Wavelength Propagation Capability (LWPC) model International Reference Ionosphere (IRI) model Communication and navigation |
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