Research on Ionospheric Grid Correction Strategy Based on Chinese Region

The estimate of Grid Ionospheric Vertical Delay (GIVD) and Grid Ionospheric Vertical Delay Error (GIVE) is the core content of ionospheric delay processing section in Satellite Based Augmentation Systems (SBAS). At present, WAAS and EGNOS respectively use Kriging method and Inverse Distance Weighting (IDW) method to estimate GIVD and GIVE. The existence of a fixed ionospheric abnormal zone at low latitudes south of the Yangtze River in China led to the advantages and disadvantages of the two algorithms in different regions of China. Aiming at this problem, this paper takes two mature methods of ionospheric grid correction as a reference, combined with the distribution characteristics of ionosphere in China, selected the measured data in China for simulation analysis. According to the comparative analysis of the simulation performance of the algorithm, this paper proposes an algorithm combination of strategies. This paper selects the measured data of 31 monitoring stations and 30 user stations from Crustal Movement Observation Network of China (CMONOC) for verification. Firstly, the spatial correlation characteristics of the ionosphere over China are analyzed and the applicability of the two algorithms to China is adjusted. Secondly, we compare the performance of the two mature algorithms. Finally, based on the comparative analysis, combined with the theoretical analysis of the use of two algorithms, this paper puts forward the combination strategy. In the area north of the Yangtze River, the ionospheric delay error model is stable and Kriging method is adopted to obtain a larger service area and better calibration performance. At the same time, in the area south of the Yangtze River, in order to counter the frequent occurrence of ionospheric abnormal, IDW method was chosen to ensure the integrity. The results show that compared with the IDW method alone, the combination accuracy is improved and the service area in the marginal area is expanded. Compared with the single plane Kriging method, the combined method ensures the integrity of the ionosphere active area in the south of the Yangtze River.