国际GNSS服务组织全球电离层TEC格网精度评估与分析

Evaluation and analysis of the global ionospheric TEC map in the frame of international GNSS services

国际GNSS服务组织(International GNSS Services,IGS)发布的全球电离层TEC格网(Global lonospheric Map,GIM)是利用GNSS进行电离层研究的主要数据源之一.IGS电离层工作组于2016年2月正式授予中国科学院为全球第五个电离层数据分析中心,由测量与地球物理研究所和光电研究院联合实施.本文系统地总结和展示了IGS电离层工作组对各分析中心GIM评估的结果;此次评估以基准站实测电离层TEC、测高卫星电离层TEC为参考,给出了各分析中心1998-2015年GIM的总体性能.结果显示:随着IGS基准站日益增多,各分析中心GIM内符合精度由4.5~7.0TECu提升至2.5-3.5TECu;不同分析中心GIM一致性从3.0~4.5TECu提升至2.0~3.5TECu;相对于测高卫星电离层数据,CODE、CAS、JPL和UPC分析中心的GIM精度相对较高(约4.0~4.5TECu),但是在不同测高卫星评估结果之间存在不同的系统性偏差.

The Global Ionospheric Map （GIM） released by the International GNSS Services （IGS） is becoming one of the important data sources for the ionosphere-related research and applications. The IGS ionospheric workgroup granted Chinese Academy of Sciences （CAS） as the fifth Ionosphere Associate Analysis Center （IAAC） routinely providing daily GIM to IGS and this new center is implemented by the Institute of Geodesy and Geophysics （IGG） in Wuhan and the Academy of Opto-Electronics （AOE） in Beijing. This paper briefly summaries the GIM evaluation results carried out by IGS ionospheric workgroup. The GIMs from current and new IAACs during the period of 1998--2015 were assessed by the ionospheric TEC from global GNSS stations and the altimetry satellites, such as TOPEX, JASON1 and JASON2, and the comparisons with the IGS final GIM product is conducted as well. The results show that （1） the precisions of GIM are improved from 4.5-7.0TECu to 2.5-3.5TECu and the consistencies among the GIMs from different IAACs are reduced from 3.0-4.5TECu to 2.0-3.5TECu with the increasing number of global GNSS stations in the last 2 decades. （2） Compared with the ionospheric TEC from altimetry satellites, the accuracies of GIM from CODE, CAS, JPL and UPC are about 4.0-4.5TECu, but different systemic biases exist between the GIM and the ionospheric TEC from different altimetry satellites.