Real-Time Regional Ionospheric Total Electron Content Modeling Using Spherical Harmonic Function

The Ionospheric Total Electron Content (TEC) model is very important for navigation, precise positioning and some other applications. In recent years, with the fast development of the local Continuously Operating Reference Stations (CORS) in China, determining precise local Ionospheric TEC model is very attractive for local precise positioning. Ionosphere delay is one of the most error sources. At present, the establishment of large-scale CORS system in china provided the conditions for establish real-time regional Ionospheric model using spherical harmonic function. In this paper, we will model the ionospheric TEC using the GPS geometry-free combination observable with the low order spherical harmonic function, meanwhile, the DCBs will also be solved with the Vertical TEC (VTEC). In the experiment, about 20 IGS stations from Europe are chosen to simulate a CORS network, a set of ionosphere coefficients is assumed every 2 h. By comparisons with the IGS Analysis Centre's model, it shows that the mean difference of the DCBs is less than 0.35 ns with the RMS about 0.2 ns, and the difference of the VTEC is less than 3 TECU.