Modeling Regional Ionosphere Using GPS Measurements over China by Spherical Cap Harmonic Analysis Methodology

Based on spherical cap harmonic analysis(SCHA) methodology,the SCHA model to fit regional ionosphere total electronic content(TEC) over China is developed,and the accuracy and validity of this new TEC model by the GPS measurements from two Chinese domestic GPS observation networks in 2004 are evaluated.The results show that SCHA model is preferable since the overall modeling residual with respect to TEC measurements is relatively small,and the residual distribution is well-proportioned within temporal and spatial domain.Moreover,the time series of SCHA coefficients reflect the procecss of ionospheric activity explicitly,e.g.,the coefficient 0,0 depicts the mean regional ionosphere TEC,which is confirmed by the result deduced by GIM parameters of CODE,one of IGS analysis centers.That implies that SCHA mode can be used to predicate regional ionospheric TEC.Due to more GPS measurements over China involved in the modeling,SCHA model provides more precise TEC estimation in the region than IONEX data delivered by IGS analysis centers.