Performance evaluation of real-time global ionospheric maps provided by different IGS analysis centers
Performance evaluation of real-time global ionospheric maps provided by different IGS analysis centers
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DOI：
10.1007/s10291-019-0904-5
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发表时间：
2019-08
期刊：
影响因子：
4.9
通讯作者：
X. Ren;Jun Chen;Xingxing Li;Xiaohong Zhang;Mohamed Freeshah
中科院分区：
文献类型：
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作者：
X. Ren;Jun Chen;Xingxing Li;Xiaohong Zhang;Mohamed Freeshah
随着实时精密钟轨产品的发展，高精度实时电离层产品已成为实现实时单频精密单点定位的最关键资源之一。幸运的是，有几个国际GNSS服务（IGS）分析中心，例如，UPC、WHU和CAS提供实时全球电离层图（RT-GIM）。我们详细评估这些地图超过2年的不同方面。首先，进行RT-GIM和与IGS最终GIM（IGSG GIM）差分的1天预测电离层产品（C1 PG GIM）。第二，利用Jason-2/3数据的电离层垂直总电子含量作为海洋区域RT-GIM质量评价的参考。第三，选取22个未用于RT-GIM、C1 PG GIM和IGSG GIM生成的台站，采用倾斜总电子含量差（dSTEC）方法对大陆区域RT-GIM的精度和一致性进行了评估。最后，基于SF-PPP解决方案，验证了RT-GIM在位置域的性能。结果表明，RT-GIM的精度略低于C1 PG GIM和IGSG GIM。与IGSG GIM相比，所有RT-GIM和C1 PG GIM的平均差异均较小（UPC RT-GIM、CAS RT-GIM、WHU RT-GIM、C1 PG GIM），TECU为（−0.97、− 0.90、− 0.77、− 0.80）。在海洋区域，RT-GIM的表现几乎与C1 PG GIM相同，但略差于IGSG GIM。对于（UPC RT-GIM、CAS RT-GIM、WHU RT-GIM、C1 PG GIM、IGSG GIM），相对于Jason-2的STD分别为（3.96、3.05、3.25、3.12、2.54）TECU，相对于Jason-3的STD分别为（4.94、3.24、3.38、3.24、2.65）TECU。与大陆地区地面站的dSTEC值比较，UPC RT-GIM、CAS RT-GIM、WHU RT-GIM、C1 PG GIM、IGSG GIM的RMS分别为（4.02，2.16，2.29，1.86，1.49）TECU。在位置域，经RT-GIM和C1 PG GIM校正后的SF-PPP解的定位精度在水平方向可达分米级，在垂直方向可达米级，比IGSG GIM差。同时，SF-PPP的定位精度的RT-GIM校正是几乎相同的，使用C1 PG GIM。对于RT-GIM，CAS RT-GIM的精度略优于其他两种RT-GIM。
With the development of real-time precise clock and orbit products, high-precision real-time ionospheric products have become one of the most critical resources for real-time single-frequency precise point positioning. Fortunately, there are several international GNSS service (IGS) analysis centers, e.g., UPC, WHU, and CAS, that are providing real-time global ionospheric maps (RT-GIMs). We evaluate these maps in detail over 2 years for different aspects. First, the RT-GIMs and 1-day predicted ionospheric products (C1PG GIM) differenced with the IGS final GIMs (IGSG GIM) are performed. Second, ionospheric vertical total electron content from Jason-2/3 data is set as a reference to evaluate the quality of RT-GIMs over oceanic regions. Third, 22 stations, which are not used in the generation of RT-GIMs, C1PG GIM, and IGSG GIM, are selected and the difference of slant total electron content (dSTEC) method is used to assess the accuracy and consistency of RT-GIMs over continental regions. Finally, the performance of RT-GIMs in the position domain is demonstrated based on SF-PPP solutions. The results show that the accuracy of the RT-GIMs is slightly worse than that of C1PG GIM and IGSG GIM. All RT-GIMs and the C1PG GIM have a smaller mean difference compared to the IGSG GIM by (−0.97, − 0.90, − 0.77, − 0.80) TECU for (UPC RT-GIM, CAS RT-GIM, WHU RT-GIM, C1PG GIM). Over oceanic regions, the RT-GIMs perform nearly the same as the C1PG GIM, but a slightly worse than IGSG GIM. The STDs are (3.96, 3.05, 3.25, 3.12, 2.54) TECU relative to Jason-2 and (4.94, 3.24, 3.38, 3.24, 2.65) TECU relative to Jason-3 for (UPC RT-GIM, CAS RT-GIM, WHU RT-GIM, C1PG GIM, IGSG GIM), respectively. Comparing with dSTEC values observed from the selected ground stations over continental regions, the RMS is (4.02, 2.16, 2.29, 1.86, 1.49) TECU for (UPC RT-GIM, CAS RT-GIM, WHU RT-GIM, C1PG GIM, IGSG GIM). In the position domain, the positioning accuracy of SF-PPP solution corrected by the RT-GIMs and C1PG GIM can reach decimeter level in the horizontal direction and meter level in the vertical direction, which is worse than obtained by IGSG GIM. Meanwhile, the positioning accuracy of SF-PPP corrected by RT-GIMs is almost the same as that obtained using C1PG GIM. For RT-GIMs, the accuracy of the CAS RT-GIM is slightly better than that of the other two RT-GIMs.