Brazilian active GNSS networks as systems for monitoring the ionosphere

Abstract

This research shows the viability of using Global Navigation Satellite System (GNSS) stations from Brazilian active networks in monitoring the ionosphere. Various indexes of ionospheric irregularities and scintillation of GNSS signals, estimated in real-time and post-processed from GNSS data, are explored for this purpose. This way, an increase in the spatial resolution of ionospheric information is provided, allowing the generation of maps of scintillation and irregularities in observing the spatial and temporal behavior of the layer’s activity cycle, since the number of ionosondes, imagers, and radars is insufficient for monitoring the irregularities in Brazil. Experiments to evaluate the estimates of the indexes are performed for periods of high and low variability of electrons. Three Brazilian networks are used: the Brazilian Network for Continuous Monitoring (RBMC), the GNSS Active Network of Sao Paulo State (GNSS-SP), and CIGALA/CALIBRA. The results are compared with data from ionosondes and PolaRxS-PRO Septentrio receivers, proving compatible with moderate to high correlations. An analysis of the seasonal variation during the peak of solar cycle 24 is carried out. The maps allow identifying the displacement of ionospheric irregularities along the magnetic equator over Brazil, from northeast to southwest, starting at 7:00 pm and ending at 2:00 am local time. Real-time monitoring is carried out for the summer solstice in the southern hemisphere, and results are consistent with those from the post-processed mode. The indexes and maps can be applied to the analysis of GNSS positioning. Real-time ionospheric information can be used in important practical applications because the displacement monitoring of irregularities allows prior knowledge of whether there will be a deterioration of positioning accuracy in a certain region.