GPS Solutions ( IF 4.5 ) Pub Date : 2022-06-08 , DOI: 10.1007/s10291-022-01259-7
Ping Yin , Shengran Shi , Dandan Ren
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In Satellite-Based Augmentation Systems (SBASs), e.g., the US Wide-Area Augmentation System (WAAS), the planar method and the kriging method based on the thin-shell model have been used to estimate the ionospheric grid delay (IGD). Generally, the kriging method can achieve higher accuracy than the planar method. In comparison with the thin-shell model, ionospheric tomography overcomes the limitations of the 2D ionospheric delay modeling and can realize 3D or even 4D ionospheric electron density reconstructions, especially suitable over disturbed periods. For the first time by virtue of electron density inversions, a tomographic method and a kriging-combined tomographic method are proposed innovatively to apply for estimating IGDs over part of the WAAS region using 32 ground stations during ionospheric disturbances on September 7–9, 2017. Then, independent dual-frequency Global Positioning System (GPS) data at six stations are applied to validate estimated IGD results from these four methods. It is shown that the overall errors of the planar method, the kriging method, the tomographic method, and the kriging-combined tomographic method over 3 days are decreased one by one, while errors using the latter two methods are quite similar. When focusing on the strong disturbed times, the latter two tomographic methods can obtain more accurate IGD than the former two methods based on the thin shell model. Tomographic total electron content (TEC) maps over the study area are also reconstructed to help analyze the underlying mechanism at different stations. It is also noted that the kriging-combined tomography has little improvement in IGD estimates in comparison with the tomographic method alone during strong ionospheric disturbances.
中文翻译:
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基于电离层断层扫描的 SBAS 电离层网格延迟估计:2017 年 9 月 7-9 日的案例研究
在星基增强系统(SBAS),例如美国广域增强系统(WAAS)中,基于薄壳模型的平面法和克里金法已被用于估计电离层网格延迟(IGD)。一般来说,克里金法可以达到比平面法更高的精度。与薄壳模型相比,电离层层析成像克服了2D电离层延迟建模的局限性,可以实现3D甚至4D电离层电子密度重建,尤其适用于扰动时段。2017年9月7-9日电离层扰动期间,首次利用32个地面站,创新性地提出了层析成像方法和克里金组合层析成像方法,用于估计WAAS部分区域的IGD。然后,应用六个站的独立双频全球定位系统 (GPS) 数据来验证这四种方法的估计 IGD 结果。结果表明,平面法、克里金法、层析法和克里金组合层析法3天后的总体误差逐一减小,而后两种方法的误差比较接近。在关注强扰动时,后两种断层扫描方法比前两种基于薄壳模型的方法可以获得更准确的IGD。还重建了研究区域的断层总电子含量 (TEC) 图,以帮助分析不同站点的潜在机制。