Positioning performance of the NTCM ionospheric model driven by Galileo Az coefficients

Abstract

The interaction of GNSS signals with the ionosphere may cause link related errors of up to 100 m at GNSS frequencies in the L-band. To aid single frequency applications, the Neustrelitz Total Electron Content Model driven by Galileo ionization coefficients (NTCM-GlAzpar) has been proposed as an adequate solution to mitigate propagation errors. For the first time, we present a global statistical validation of the NTCM-GlAzpar model in the position domain by comparing its results with the results of the Galileo NeQuick and GPS Klobuchar models. For this purpose, we used the GNSS analysis tool gLAB in the Standard Point Positioning (SPP) technique. The used GNSS data corresponds to a one-month period of perturbed solar activity (December 2014) and one-month period of quiet conditions (December 2019). We achieved a worldwide coverage with up to 73 IGS stations. The statistical analysis of the hourly mean 3D position error shows that NTCM-GlAzpar outperforms the Klobuchar model. Also, the results achieved with NTCM-GlAzpar are slightly better or comparable to the results obtained with NeQuickG. The performance of NTCM-GlAzpar decreases slightly for conditions of reduced solar activity – at night time, higher latitudes and low perturbations. Nevertheless, simple software adaptations and a low computational time make NTCM-GlAzpar an alternative practicable algorithm to improve the accuracy of positioning applications.