Research on the regional short-term ionospheric delay modeling and forecasting methodology for mid-latitude area

The modeling and forecasting of the ionospheric delay is crucial in Global Positioning System (GPS) applications. In this study, a mathematical model that combines the polynomial function with B-spline function is put forward to estimate the regional ionospheric delay. In order to increase the forecasting accuracy, an integration forecasting method based on Holt---Winter model and Markov model is proposed to forecast the regional ionospheric delay. The Holt---Winter model is used to forecast the periodicity of vertical total electron content (VTEC), and the Markov model is employed to refine the residuals produced by the Holt---Winter model and forecast the fluctuation of VTEC. The two approaches are applied to real data obtained from the ground-based GPS observations of Jiangsu Continuously Operating Reference Stations. The results illustrate the effectiveness of the 2-h interval ionospheric delay modeling method, and the feasibility of the short-term ionospheric delay forecasting method for mid-latitude area. The applicability of the methodology during the ionospheric storms in the low-latitude area is also discussed.