On the solar radio burst event that occurred on August 28, 2022, and its impact on GNSS signals measured by distributed scintillation monitors in the American sector

As part of an effort to observe and study ionospheric disturbances and their effects on radio signals used by Global Navigation Satellite Systems (GNSS), alternative low-cost GNSS-based ionospheric scintillation and total electron content (TEC) monitors have been deployed over the American sector. The monitors (ScintPi) that comprise the network are created using single-board computers and commercial off-the-shelf (COTS) GNSS receivers (Socola and Rodrigues 2022). During inspection of the observations made at UT Dallas, we found unusual increases in the amplitude scintillation index (S4) for measurements made on August 28, 2022 between approximately 17:45 UT and 18:20 UT. Dual-frequency observations made by the sensor allowed us to determine that the increases in S4 were not accompanied by total electron content (TEC) variations, indicating that the S4 increases were not caused by ionospheric irregularities. Further analyses found that increases in the S4 values were observed simultaneously by other monitors. This finding, combined with the fact that the S4 increases were observed by monitors in daytime sector, led us to consider effects of solar origin. We found that the observed S4 increases resulted from C/No variations caused by a solar radio burst (SRB) event that occurred during an intense period of solar activity, which included two M-class X-ray solar flares and a Halo coronal mass ejection. The measurements also allowed us to quantify the impact of the SRB on GNSS signals. The observations show that the SRB caused maximum C/No fadings of about 8 dB-Hz (12 dB-Hz) on L1 ~ 1.6 GHz (L2 ~ 1.2 GHz) for signals observed by the monitor in Dallas for which the solar zenith angle was minimum (~24.4o) during the SRB. The results exemplify the usefulness of the ScintPi network for studies beyond those associated with ionospheric irregularities and scintillation.