Comparison of Total Electron Content (TEC) Maps over Brazil from Different Sources

Total Electron Content (TEC) allows to evaluate the state of the ionosphere. Radio waves like GNSS signals traversing the ionosphere suffer delays and refraction. Ionospheric plasma irregularities may be generated in the equatorial regions after sunset and extend to low latitudes forming large plasma depleted regions named ionospheric bubbles. Signature of these bubbles can be observed at TEC maps. Inside plasma bubbles smaller scale size irregularities are generated causing scintillation in GNSS signals. This work compared TEC maps from some sources, with different temporal and spatial resolutions/coverage. Significant differences were found. For each source, there are differences in the treatment and preprocessing of raw data in order to get the absolute TEC values, which are interpolated to get grid values of the map. Even for the same source there are significant differences in the density of monitoring stations according to the region. A case of study concerning scintillation is also analyzed using the corresponding TEC and scintillation maps. TEC maps employed here encompass the years from 2022 to 2024, in the growing phase of the current solar cycle 25. The months of March, June, September and December were selected to take into account the TEC seasonal variation.