Precise Ionosphere Modeling Using Regional GPS Network Data

The ionosphere affects the electromagnetic waves that pass through it by inducing an additional transmission time delay. The ionosphere influence has now become the largest error source in GPS positioning and navigation after the turn-off of the Selective Availability (SA). In this paper, methods of 2D gridbased and 3D tomography-based ionospheric modeling are developed based on regional GPS reference networks. Performance analysis was conducted using data from two different regional GPS reference networks. The modeling accuracy of the vertical TEC (VTEC) is at the level of several TECU for 2D ionospheric modeling and about one TECU for 3D tomographic modeling after a comparison to independent ionospheric map data or directly measured ionospsheric TEC values. The data analysis has indicated that the modeling accuracy based on the 3D tomography method is much higher than the 2D grid-based approach.