Evaluation of the dusk and early nighttime Total Electron Content modeling over the eastern Brazilian region during a solar maximum period

Abstract

The ionosphere is one of the main sources of errors for the GNSS (Global Navigation Satellite System) users in low-latitude regions. The ionosphere delays the signal propagation, directly influencing the pseudorange estimation, which is fundamental for positioning estimation. This study aims at evaluating empirical and theoretical models that generate profiles of Total Electron Content (TEC), with respect to their ability to represent the spatiotemporal distribution of the ionospheric plasma. For this purpose, the TEC data calculated from measurements obtained by receivers from the Brazilian Network for Continuous Monitoring of GNSS Systems (RBMC) were compared with ionospheric models that provide the TEC values. The TEC calculation procedure is presented in the manuscript. The Klobuchar model, the empirical model IRI-2016, which has the NeQuick model integrated in its calculations, and the SAMI2 model were evaluated. Data from 2 years around solar maximum period was used considering averaged values over Brazilian region. The evaluations carried out between the TEC values obtained from the models and the real TEC data showed that the models have some deviations, therefore requiring future improvements. According to the results, the deviations may reach approximately 7 m and are originated from physical peculiarities on the spatial environment over the Brazilian region.