In this work, we analyze the phase scintillation index observed from the GPS, GLONASS, Galileo, and BeiDou satellite constellations, for a continuous period of three years. Our analysis reveals an elevated level of L1 phase scintillation observed from most GLONASS satellites, and none of the other GNSS constellations during the same period. This is of particular interest as the abnormality was observed during a solar minimum period, and from satellites labeled as healthy. Our observations were verified with data from four different receivers located in different regions. The goal of this study is to highlight these abnormal phase scintillations from GLONASS satellites as they may adversely affect the reliability and integrity of the GLONASS positioning service, especially during periods of heightened geomagnetic activity.

In this letter, we study the temporal and spatial variability of ionospheric irregularities by generating high-resolution maps of the observed amplitude scintillation index (S4) using data from a multi-constellation and multi-frequency GNSS receiver. The study is located in the Arabian Peninsula region, which falls under the northern crest of the equatorial ionization anomaly (EIA). Even though the study was conducted during a solar minimum period, considerable pre-sunset scintillation occurrences have been observed between 15-17 local time, particularly during the winter solstices. While most scintillation occurrences have been observed at low elevation (20 to 25 degrees), a considerable number of scintillation causing ionospheric irregularities have been observed towards the north, east, and southeast of the receiver location, for elevation ranging from 40 to 60 degrees. Out of all the GNSS constellations with medium-earth-orbit (MEO) satellites, GPS was the most impacted by amplitude scintillation, while BeiDou and Galileo satellites were the least affected. It is anticipated that the patches of ionospheric irregularities reported in this work will be further enhanced as solar activity increases in the coming years. Therefore, this work can serve as a reference for future studies during periods of increased geomagnetic activity.