Li, Min, Yuan, Yunbin, Zhang, Ting, Xu, Hanying, Huo, Xingliang, and Zhang, Wenyao
Additional ionospheric information is essential for mitigating errors in single‐frequency (SF) Global Navigation Satellite Systems (GNSS) positioning. The increasing number of low‐cost dual‐frequency (DF) receiver users faces limitations in tracking DF observables compared to traditional geodetic receivers. Consequently, ionospheric correction algorithms (ICAs) are also essential for low‐cost DF devices in hybrid‐frequency positioning. To evaluate the performance of commonly used ICAs during solar cycle 25, our study presents a global statistical investigation of the contribution of five broadcast ionospheric models (BIMs) and the International GNSS Service (IGS) combined real‐time global ionospheric maps (IRTG) to the positioning domain, covering both quiet and perturbed ionospheric conditions. The BIMs investigated include the GPS Klobuchar (GPSK), Galileo NequickG (NEQG), NTCM‐GlAzpar (NTCMG), BDS‐2 Klobuchar (BDSK), and BeiDou Global Ionospheric delay correction Model (BDGIM). Experimental results from standard point positioning indicate that IRTG demonstrates superior overall accuracy compared to all BIMs, with a mean 3D root mean squared (RMS) of 2.76 m during perturbed period. Specifically, GPSK, NTCMG, NEQG, BDGIM, and BDSK exhibit RMS values of 2.03, 1.67, 1.72, 1.62, and 2.36 m during quiet conditions, and 4.02, 3.17, 2.86, 3.14, and 4.44 m during perturbed conditions, respectively. Among the BIMs, NEQG demonstrates superior performance at middle and high latitudes but exhibits lower accuracy than NTCMG and BDGIM at low latitudes during daytime under quiet conditions. BDGIM performs slightly better than NTCMG at low latitudes but slightly worse at high latitudes. BDSK shows notable improvement for high‐ and mid‐latitude regions since 3 June 2020. Plain Language Summary: The ionospheric delay caused by free electrons in the ionosphere is a significant source of error in single‐frequency Global Navigation Satellite Systems (GNSS) positioning. To correct for this, broadcast ionospheric models (BIMs) developed by GPS, BDS, and Galileo, as well as real‐time global ionospheric maps (RT‐GIMs) provided by the International GNSS Service (IGS), are widely used. This study comprehensively analyzed the contribution of five BIMs and the IGS combined RT‐GIMs (IRTG) to GNSS positioning during different ionospheric conditions in solar cycle 25. Using data from 34 IGS stations worldwide over 123 days in 2020 and 2023, we conducted standard point positioning experiments. Overall, the average order of decreasing accuracy during quiet conditions were BeiDou Global Ionospheric delay correction Model (BDGIM), NTCMG, NEQG, GPSK, and BDSK, while during perturbed conditions, the order was IRTG, NEQG, BDGIM, NTCMG, GPSK, and BDSK. Key Points: We investigated the contribution of five broadcast ionospheric models (BIMs) and IRTG to Global Navigation Satellite Systems positioning across latitudinal and diurnal variations during solar cycle 25IRTG outperforms all BIMs. Among all BIMs, BeiDou Global Ionospheric delay correction Model, and NeQuickG perform the best during the quiet and perturbed period, respectivelyAlthough BDSK shows notable improvement for high latitudes since June 2020, it still exhibits the worst position performance among all BIMs [ABSTRACT FROM AUTHOR]