Applicability analysis of kriging methodology for China

A non-nominal condition of ionosphere likely makes the largest threat for aviation service of the Single Frequency (SF) Satellite-Based Augmentation System (SBAS). The Wide Area Augmentation System (WAAS) located in the mid-latitude region has updated the ionospheric grid correction technology from the Inverse Distance Weight (IDW) method to the Kriging methodology that was made primarily to improve system service availability and ensure system service integrity. The implementation of the Kriging methodology utilizes a dynamic fit domain to select a set of measurements and constructs two terms representing the threat of inaccurate model assumptions and the threat of spatial variations, respectively. The advantage of this methodology is that it not only reduces the dependence of the ionospheric augmentation information calculation on the distribution of reference stations but also improves system service performance. However, the BDSBAS (BeiDou Satellite-Based Augmentation System) service area, except for the terrain restricted the distribution of reference stations, has a larger latitude span. It has mid-latitude and low-latitude ionosphere characteristics, especially the irregularity of the low-latitude ionosphere will seriously affect the BDSBAS SF service performance. This paper analyzes the applicability of the Kriging methodology over China and constructs the quantitative relationship of observability between ionospheric measurements and the estimated location to solve the problem. The results show that the Kriging methodology can be used to calculate ionospheric delay augmentation information in the BDSBAS SF augmentation service. The search parameters of the dynamic fit domain in the Kriging can keep unchanged. The research of algorithm for China should focus on the analysis and modeling of ionospheric irregularities, develops the study of error uncertainty to meet the integrity requirements for aviation and improves the services of the system. Additionally, if there is no reference station in the overseas area, it is still difficult to implement effective monitoring of the integrity risk of edge grids caused by ionospheric irregularities, even under the conditions of multi-constellation.