Technical note on the multi-GNSS, multi-frequency and near real-time ionospheric TEC monitoring system for South America

Development of regional services able to provide ionospheric total electron content (TEC) maps with a high spatial resolution, and in near real-time, are of high importance for applications and the research community. We provide here the methodologies, and a preliminary assessment, of such a system. The system relies on the public Global Navigational Satellite Systems (GNSS) infrastructure in South America, it incorporates data from multiple constellations (currently GPS, GLONASS, Galileo and BeiDou), it employs multiple frequencies, and it produces continental wide TEC maps with a latency of just few minutes. A year-round comparison of the produced maps with several products issued by the International GNSS Service (IGS) resulted in mean biases lower than 1 TEC units (TECU), whereas their evaluation against direct and independent GNSS-based slant TEC measurements resulted in accuracies of the same magnitude.