Optimized NeQuick Ionospheric Model for Point Positionig

AZPILICUETA, F.; NAVA, B.; COISSON, P.; RADICELLA, S.

Tokyo, Japón.

Workshop; 2003 International Symposium on GPS/GNSS,; 2003

An assessment of NeQuick Ionospheric Model for single-frequency point positioning at global scale has been performed. The technique used has been based on the estimation of the horizontal and vertical residual errors on positioning when the ionospheric delay is corrected using NeQuick model driven by the ‘ionozation level’ parameter Az. An optimization method was developed for obtaining the Az parameter using data of a set of IGS stations with global coverage. Validation tests were done using data from an independent set of stations, also adequately distributed to make the assessment valid on a global basis. To extend the analysis to different ionospheric conditions, data used correspond to seven geomagnetically quiet days during periods of high solar activity and represent different seasonal conditions.. Values of the 95% quantile of the residual errors were computed in order to determine the accuracy level provided by the model for point positioning at its present stage of development. The final results indicate that the application of NeQuick model combined with the optimization method improves the accuracy of the vertical point position determinations in a 65%, when compared to the raw solution.