Analysis of Temporal and Spatial Variation Characteristics of Global Ionospheric TEC Grid

The correction of ionospheric delay is one of the important factors affecting the real-time positioning accuracy of satellite navigation users. It is a common method to provide ionospheric delay correction by using global ionosphere maps (GIM). The accuracy of GIM is often limited by the distribution density of GNSS tracking stations on the ground. Hence, it is especially important to establish a real-time regional ionospheric total electron content (TEC) model by using one or few GNSS tracking stations, and to generate a real-time regional ionosphere map, which provides users with regional ionospheric delay corrections. In this contribution, GIM grid data of 995 days from 2016 to 2018 provided by the Center for Orbit Determination in Europe (CODE) is adopted to analyze the TEC variations between some adjacent grid points and the TEC variations after different time intervals at a same grid point. The results show that the mean value of GIM variations with a 5° longitude interval ranges from 0.2 to 1.0 TECU, and that with a 2.5° latitude interval ranges from 0.4 to 1.4 TECU. The variation of ionospheric TEC is less than 1.0 TECU when the variation of longitude and latitude is within 1°. The mean variation of ionospheric TEC at a same grid point within 1 hour is about 1.28 TECU, and that within 30 minutes is less than 1.0 TECU. This contribution provides effective experiment verification and data support of the establishment of real-time regional (within 100 km) ionospheric TEC model, along with its applicable temporal and spatial range. Furthermore, this contribution is also significant to the researches on temporal and spatial variations of ionospheric TEC, ionospheric TEC prediction and monitoring of ionospheric anomalies and magnetic storms.