Impact of Ionospheric Model Corrections in Different Seasons of China on the SPP of GPS Systems

For GNSS satellite signals traveling from the satellite to the ground, the ionosphere is an unavoidable path. At the same time, the ionosphere is also a major error source in GNSS PNT applications. At present, both BDS and GPS broadcast ionospheric error correction model parameters to users via navigation information. The BDS broadcasts the BDGIM model with 9 parameters, while the GPS use the Klobuchar model with 8 parameters. A systematic analysis of the impact of different ionospheric models or products on the accuracy of standard Single Point Positioning (SPP) can serve as a valuable reference for global single-frequency satellite navigation users in selecting suitable ionospheric error correction methods. This paper focuses on the Chinese region and evaluates SPP performance at different latitude stations using the Klobuchar model, BDGIM model, IGS ionospheric grid products, and regionally modeled CHNION products in March, June, September, and December 2022. By comparing SPP accuracy, the correction performance of various ionospheric models and products in China is analyzed. The results show that the Klobuchar model provides the lowest SPP accuracy in China. The BDGIM model improves the average positioning accuracy by 20% across four stations. For mid-latitude and low-latitude stations BJF1, ZLTG, and HKSL, using the CHINON product for ionospheric correction results in a monthly average precision is 1.65, 1.27, 3.2, and 2.87 m, respectively. with the IGS final product, the monthly average positioning precision is 1.6, 1.37, 3.1, and 2.73 m.