A new model for total electron content based on ionospheric continuity equation

Abstract

With the development of the Global Navigation Satellite System (GNSS), the accuracy and reliability requirements on observations are constantly increasing. The effect of ionospheric disturbance is not negligible, especially for accurate GNSS applications. To reduce the influence of ionospheric delay and disturbance, this study uses the Ionospheric Continuity Equation (ICE) to establish a new model for Total Electron Content (TEC), which takes both photochemical and transportation processes into account and named ICE model. Experimental results show that the ICE model achieves accuracies higher than Spherical Harmonic (SH) and polynomial models on geomagnetism quiet and disturbance days, and more prominent advantages appear at nighttime. By the test of Satellite Differential Code Bias (SDCB) estimation, the deviations of the polynomial and the ICE models are nearly the same whatever the geomagnetic field is quiet or disturbance; however, the estimation accuracy of the ICE model is slightly better than the polynomial model. Spatial and temporal adaptability tests indicate that the ICE model can achieve accuracies of 0.5 TECU and 1 TECU on time scales of approximately 25 min and 100 min, respectively. On the weak disturbance or quiet day, these accuracies can be achieved on the spatial scales of approximately 200 km and 600 km. The credibility of the ICE model is evaluated by Nash–Sutcliffe efficiency. The evaluation results assigned that the ICE model has higher credibility than the SH and polynomial models and better immunity to geomagnetic disturbance.