Satellite-beacon Ionospheric-scintillation Global Model of the upper Atmosphere (SIGMA) II: Inverse modeling with high-latitude observations to deduce irregularity physics
Satellite-beacon Ionospheric-scintillation Global Model of the upper Atmosphere (SIGMA) II: Inverse modeling with high-latitude observations to deduce irregularity physics
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DOI：
10.1002/2016ja022943
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发表时间：
2016-09-01
影响因子：
2.8
通讯作者：
Weatherwax, A. T.
中科院分区：
文献类型：
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作者：
Deshpande, K. B.;Bust, G. S.;Weatherwax, A. T.
电离层闪烁是由电离层电子密度的不规则性引起的。电离层不规则性的表征对于进一步理解其物理学基础是重要的。我们的目标是描述中（0.1- 10公里）到中（10- 100公里）尺度的高纬度不规则体，这些不规则体可能产生这些不规则体。在本文中，我们描述了2012年3月9日地磁活跃期期间全球导航卫星系统（GNSS）观测到的不规则性。为此，沿着测量，我们使用最近开发的模式：卫星信标电离层闪烁高层大气全球模式（SIGMA）。该模型特别适用于高纬度地区，因为它考虑了这些地区磁场线的复杂几何形状，并在早期的论文中提出。我们使用逆建模技术，通过比较高速率（50 Hz）的GNSS观测模型的输出来获得不规则参数。在这项研究中，我们考虑从北方和南方高纬度的实验观测。结果表明，相对于振幅脉动，相位脉动占优势，这意味着在GPS频率下存在着比菲涅尔尺度更大的不规则性，谱指数范围为2.4 ~ 4.2，RMS数密度范围为3e 11 ~ 2.3e12 el/m（3）。我们从只考虑弱散射的逆方法中获得的最佳拟合与观测结果基本一致。最后，我们提出了一些改进，以促进实现一个独特的解决方案，这样的逆问题的可能性。
Ionospheric scintillation is caused by irregularities in the ionospheric electron density. The characterization of ionospheric irregularities is important to further our understanding of the underlying physics. Our goal is to characterize the intermediate (0.1-10km) to medium (10-100km) scale high-latitude irregularities which are likely to produce these scintillations. In this paper, we characterize irregularities observed by Global Navigation Satellite System (GNSS) during a geomagnetically active period on 9 March 2012. For this purpose, along with the measurements, we are using the recently developed model: Satellite-beacon Ionospheric-scintillation Global Model of the upper Atmosphere (SIGMA). The model is particularly applicable at high latitudes as it accounts for the complicated geometry of the magnetic field lines in these regions and is presented in an earlier paper. We use an inverse modeling technique to derive irregularity parameters by comparing the high rate (50Hz) GNSS observations to the modeled outputs. In this investigation, we consider experimental observations from both the northern and southern high latitudes. The results include predominance of phase scintillations compared to amplitude scintillations that imply the presence of larger-scale irregularities of sizes above the Fresnel scale at GPS frequencies, and the spectral index ranges from 2.4 to 4.2 and the RMS number density ranges from 3e11 to 2.3e12 el/m(3). The best fits we obtained from our inverse method that considers only weak scattering mostly agree with the observations. Finally, we suggest some improvements in order to facilitate the possibility of accomplishing a unique solution to such inverse problems.