An observational study of low-latitude ionospheric disturbances using the Low lAtitude long Range Ionospheric raDar
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摘要: 在低纬电离层,等离子体泡和行进式扰动是两种重要的电离层扰动现象。它们能够影响无线电波传播,干扰卫星通讯和导航定位系统的正常工作。由于陆基探测手段的局限,目前对低纬海洋上空的电离层行进式扰动和等离子体泡观测仍存在大量空白。本文基于子午工程二期海南低纬超视距电离层雷达(LARID),介绍了一种超视距探测低纬电离层扰动的方法,实现了对电离层等离子体泡的追踪和行进式扰动的二维结构成像。LARID对等离子体泡的定位结果与GNSS闪烁观测结果一致,对电离层行进式扰动的观测结果与GNSS TEC观测存在显著差异。这种差异可能部分来源于白天西向风场对重力波的过滤效应。鉴于LARID目前只能观测准东/西方向传播的电离层行扰和雷达东西方向大范围的电离层不均匀体,本文最后给出了一种将LARID观测方位拓展至全向(360°)的方法,有效增大了其对背景电离层扰动和不均匀体的探测范围。
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关键词:
- 低纬超视距电离层雷达 /
- 赤道等离子体泡不均匀体 /
- 电离层行进式扰动 /
- 全向超视距电离层雷达
Abstract: In the low-latitude ionosphere, the equatorial plasma bubble (EPB) irregularities and traveling ionospheric disturbances (TID) are two important space weather phenomena. These disturbances can affect radio wave propagation, disrupting satellite communications and navigation positioning systems. Due to the limitations of ground-based detection techniques, substantial observational gaps remain regarding ionospheric TIDs and irregularities over low-latitude oceanic regions. This study introduces an over-the-horizon detection method for low-latitude ionospheric disturbances using the Low-lAtitude long Range Ionospheric raDar (LARID) located in Hainan, China. By resolving the elevation angle of arrival based on the phase difference between the radar's main array and interferometer array, LARID can determine the spatial location of ionospheric disturbances. Leveraging its multi-beam observation capability, we have achieved two-dimensional imaging of TID structures and retrieved their wavelengths and propagation directions. The localization results for EPBs show good agreement with S4 index data from GNSS receivers. Significant differences exist between the observed TIDs and GNSS TEC measurements, which may be partly attributed to the filtering effect of daytime westward wind fields on atmospheric gravity waves. While LARID is currently only capable of observing quasi-east/west propagating TIDs and ionospheric irregularities along the east-west direction, this study finally proposes a method to extend its observational azimuth to full 360° coverage. Ray-tracing experiments demonstrate that this expansion can effectively enhance LARID's detection coverage for background ionospheric disturbances and irregularities. -
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