Monitoring the ionosphere using networks of low-cost GNSS receivers

The advent of affordable, multi-frequency, multi-constellation Global Navigation Satellite System (GNSS) receivers has opened new avenues for ionospheric monitoring and space weather research.The performance of these low-cost devices, which can access observables from multiple GNSS constellations, makes them suitable for scientific and technological applications previously limited to high-end equipment.Indeed, recent studies have demonstrated the effectiveness of affordable receivers in retrieving ionospheric parameters.For example, [1] highlighted the high degree of correlation between the estimated vertical Total Electron Content (TEC) values obtained by a low-cost dual-frequency receiver and those obtained by a scientific-grade instrument.In [2] a comparative study between a geodetic and an affordable receiver was performed in terms of accuracy of VTEC and carrier-to-noise-density ratio, and similarities were found in the variation patterns of the data from both receivers, while [3] showed that low-cost GNSS receivers can also be used to estimate ionospheric scintillation in addition to TEC.More recently, [4] validated the quality of slant and vertical TEC data obtained from low-cost dual-frequency GNSS receivers by comparing them with results obtained from nearby geodetic receivers.The authors also demonstrated the ability of a network of 15 low-cost dual-frequency GNSS receivers to monitor the response of the Earth's ionosphere to a total solar eclipse, confirming that such networks of low-cost devices can provide scientifically valuable ionospheric information with a level of accuracy comparable to that of scientificgrade instruments.In this study, the ionospheric monitoring capabilities of the EclipseNB and ICTP networks of low-cost GNSS receivers, located at mid and low latitudes respectively, are further investigated.In particular, selected examples of TEC variations corresponding to solar flares, eclipses and geomagnetically disturbed periods will be presented.