Performance analysis of a 3D ionosphere tomographic model

A 3D high precision ionospheric model is developed based on tomography technique. This tomographic model employs GPS data observed by an operational network of dual-frequency GPS receivers. The methodology of developing a 3D ionospheric tomography model is briefly summarized. However emphasis is put on the analysis and evaluation of the accuracy variation of 3D ionosphere modeling with respect to the change of GPS data cutoff angle. Three typical cutoff angle values (15?, 20? and 25?) are tested. For each testing cutoff angle, the performances of the 3D ionospheric model constructed using tomography technique are assessed by calibrating the model predicted ionospheric TEC with the GPS measured TEC and by employing the model predicted TEC to a practical GPS positioning application—single point positioning (SPP). Test results indicate the 3D model predicted VTEC has about 0.4 TECU improvement in accuracy when cutoff angle rises from 15? to 20?. However, no apparent improvement is found from 20? to 25?. The model’s improvement is also validated by the better SPP accuracy of 3D model than its counterpart-dual frequency model in the 20? and 25? cases.