全球实时电离层模型精度分析——以CAS、CNES、NRCan及UPC产品为例

分析中国科学院（CAS）、法国国家空间研究中心（CNES）、加拿大自然资源部大地测量局（NRCan）和加泰罗尼亚理工大学（UPC）2021-01～08的全球实时电离层格网(RT-GIM)产品的精度。结果表明：1）以IGS事后全球电离层格网（GIM）为参考，CAS、CNES、NRCan和UPC产品的RMS分别为3.93 TECu、4.01 TECu、4.50 TECu和3.86 TECu；2）以基准站dSTEC为参考，CAS、CNES、NRCan和UPC产品的STD分别为4.42 TECu、4.40 TECu、4.96 TECu和4.42 TECu。在全球范围内选取21个测站进行连续7 d的定位测试，以高程方向残差95%分位数统计不同实时电离层产品的定位增益。相比于广播电离层模型的定位结果，CAS、CNES、NRCan和UPC产品在北半球高程方向的定位精度分别提升11.9%、18.3%、3.4%和15.5%。

Accuracy Analysis of Real-Time Global Ionospheric Maps from CAS,CNES, NRCan and UPC

We analyze the accuracy of the RT-GIM products during January and August 2021 from Chinese Academy of Sciences(CAS), Centre National d’Etudes Spatiales(CNES), Canadian Geodetic Survey of Natural Resources Canada(NRCan) and Polytechnic University of Catalonia(UPC). Compared to the post-processed IGS-GIM, the RMS between those RT-GIM and the IGS-GIM is 3.93 TECu for CAS, 4.01 TECu for CNES, 4.50 TECu for NRCan and 3.86 TECu for UPC. Compared to the dSTEC derived from reference stations, the STD of RT-GIM from CAS, CNES, NRCan and UPC are 4.42 TECu, 4.40 TECu, 4.96 TECu and 4.42 TECu, respectively. Based on the positioning results carried on 21 globally distributed GNSS stations during 7 consecutive days, we analyze the 95% quantile of vertical residuals to check the positioning improvement of different RT-GIM. Compared to positioning results corrected by the broadcast ionospheric model, the positioning accuracy increases by 11.9% for CAS, 18.3% for CNES, 3.4% for NRCan and 15.5% for UPC in the elevation direction of the northern hemisphere.