Validation of CAS’s final global ionospheric maps during different geomagnetic activities from 2015 to 2017

Abstract

Abstract The Chinese Academy of Sciences (CAS) has become one of the Ionospheric Associated Analysis Centers (IAACs) of the International GNSS Service (IGS) since 2016, which utilizes the approach of spherical harmonic plus generalized trigonometric series (SHPTS) for its global ionospheric maps (GIM) generation. We presented an updated status of CAS’s GIM products and evaluated the overall performance of GIMs during the period of 2015–2017 at different levels of geomagnetic activity conditions and in different latitudes, in contrast to the high-quality IGS final total electron content (TEC) maps. The results show that the root-mean-squares (RMS) of CAS’s GIMs performs varies between 1.0 and 2.5 TECu and it is almost at the same level as that of the Center for Orbit Determination in Europe (CODE). The good consistency between the CAS and IGS-final GIMs has been observed in different latitudes, though the comparison results present significant dependence on the geomagnetic and solar activities. It is found that the performance of those GIMs during perturbed period is approximately 1.1–1.9 times worse than that during the quiet period. The correlations between the individual IAACs and the IGS GIMs are also investigated. The correction of CODE-GIM and Jet Propulsion Laboratory (JPL)-GIM with respected to IGS-GIM is more significant than that of Universitat Politecnica de Catalunya/IonSAT (UPC)-GIM. In general, CAS’s GIM products exhibit good consistency with the IGS-final GIMs with an overall accuracy better than 2.5 TECu during the test period.