Artificially Induced Phase Scintillation Observed From GLONASS Signals

The phase scintillation index is a commonly used metric in the remote sensing of ionospheric irregularities. 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 non 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. Furthermore, the observations made were verified with data from three other receivers in different regions. This study was conducted to highlight these artificially induced phase scintillations from GLONASS satellites so that future studies can take them into considerations, especially during periods of heightened geomagnetic activity. Additionally, these artificially induced phase scintillations may result in loss of phase lock, as well as reduced positioning accuracy, which may have serious effects on the reliability and integrity of the GLONASS positioning service.

Artificially Induced Phase Scintillation Observed From GLONASS Signals

The phase scintillation index is a commonly used metric in the remote sensing of ionospheric irregularities. 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 non 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. Furthermore, the observations made were verified with data from three other receivers in different regions. This study was conducted to highlight these artificially induced phase scintillations from GLONASS satellites so that future studies can take them into considerations, especially during periods of heightened geomagnetic activity. Additionally, these artificially induced phase scintillations may result in loss of phase lock, as well as reduced positioning accuracy, which may have serious effects on the reliability and integrity of the GLONASS positioning service.

Anisotropic Non-Kolmogorov Turbulence Spectrum with Anisotropic Tilt Angle

With the in-depth study of atmospheric turbulence, scholars have identified that the anisotropy of turbulence cells should not be forgotten. The anisotropic non-Kolmogorov turbulence model can better characterize the actual situation of atmospheric turbulence. However, the results of recent experiments by Wang et al. and Beason et al. demonstrate that the turbulence cell has an anisotropic tilt angle, i.e., the long axis of turbulence cell may not be horizontal to the ground but has a certain angle with the ground. In this paper, we derive the anisotropic non-Kolmogorov turbulence spectra for the horizontal and satellite links with anisotropic tilt angle. Then by use of these spectra, the analytical expressions of scintillation index in the horizontal and satellite links are derived for the weak fluctuation condition. The calculation results display that the scintillation index for the horizontal and satellite links vary with the changes of anisotropic tilt angle and azimuth angle. Therefore, the anisotropic tilt angle is indispensable in the horizontal and satellite links.

Mapping of S4 Over the Arabian Peninsula During Solar Minimum

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 region is the Arabian Peninsula, which falls under the northern crest of the equatorial ionization anomaly (EIA). Even though the study was conducted during a solar minimum period, considerable occurrences of pre-sunset scintillation have been observed between 15-17 local time, particularly during the winter solstices. While most scintillation occurrences have been observed at low elevation (15 to 30 degrees), a considerable number of scintillation patches have been observed towards the north, east, and southeast of the receiver location, for elevation angles ranging from 40 to 60 degrees. Our analysis shows that BeiDou geostationary orbit (GEO) and inclined GEO (IGSO) satellites may have been the main contributor to the increased number of scintillation occurrences observed around the eastern side of the receiver as compared to the western side. Out of all the GNSS constellations with 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 would be further enhanced as the solar activity increases in the coming years. Therefore, this work can serve as a reference for future studies during periods of increased geomagnetic activity.

Mapping of S4 Over the Arabian Peninsula During Solar Minimum

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 region is the Arabian Peninsula, which falls under the northern crest of the equatorial ionization anomaly (EIA). Even though the study was conducted during a solar minimum period, considerable occurrences of pre-sunset scintillation have been observed between 15-17 local time, particularly during the winter solstices. While most scintillation occurrences have been observed at low elevation (15 to 30 degrees), a considerable number of scintillation patches have been observed towards the north, east, and southeast of the receiver location, for elevation angles ranging from 40 to 60 degrees. Our analysis shows that BeiDou geostationary orbit (GEO) and inclined GEO (IGSO) satellites may have been the main contributor to the increased number of scintillation occurrences observed around the eastern side of the receiver as compared to the western side. Out of all the GNSS constellations with 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 would be further enhanced as the solar activity increases in the coming years. Therefore, this work can serve as a reference for future studies during periods of increased geomagnetic activity.

Mapping of S4 Over the Arabian Peninsula During Solar Minimum

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 region is the Arabian Peninsula, which falls under the northern crest of the equatorial ionization anomaly (EIA). Even though the study was conducted during a solar minimum period, considerable occurrences of pre-sunset scintillation have been observed between 15-17 local time, particularly during the winter solstices. While most scintillation occurrences have been observed at low elevation (15 to 30 degrees), a considerable number of scintillation patches have been observed towards the north, east, and southeast of the receiver location, for elevation angles ranging from 40 to 60 degrees. Our analysis shows that BeiDou geostationary orbit (GEO) and inclined GEO (IGSO) satellites may have been the main contributor to the increased number of scintillation occurrences observed around the eastern side of the receiver as compared to the western side. Out of all the GNSS constellations with 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 would be further enhanced as the solar activity increases in the coming years. Therefore, this work can serve as a reference for future studies during periods of increased geomagnetic activity.

Diagnostics of Es Layer Scintillation Observations Using FS3/COSMIC Data: Dependence on Sampling Spatial Scale

The basic theory and experimental results of amplitude scintillation from GPS/GNSS radio occultation (RO) observations on sporadic E (Es) layers are reported in this study. Considering an Es layer to be not a “thin” irregularity slab on limb viewing, we characterized the corresponding electron density fluctuations as a power-law function and applied the Ryton approximation to simulate spatial spectrum of amplitude fluctuations. The scintillation index S4 and normalized signal amplitude standard deviation S2 are calculated depending on the sampling spatial scale. The theoretical results show that both S4 and S2 values become saturated when the sampling spatial scale is less than the first Fresnel zone (FFZ), and S4 and S2 values could be underestimated and approximately proportional to the logarithm of sampled spatial wave numbers up to the FFZ wave number. This was verified by experimental analyses using the 50 Hz and de-sampled FormoSat-3/Constellation Observing System for Meteorology, Ionosphere and Climate (FS3/COSMIC) GPS RO data in the cases of weak, moderate, and strong scintillations. The results show that the measured S2 and S4 values have a very high correlation coefficient of >0.97 and a ratio of ~0.5 under both complete and undersampling conditions, and complete S4 and S2 values can be derived by dividing the measured undersampling S4 and S2 values by a factor of 0.8 when using 1-Hz RO data.

Ionospheric Irregularities During Disturbed Geomagnetic Conditions Over Argentinian EIA Region

Ionospheric irregularities can severely degrade radio communication and navigation systems. Geomagnetic storms may affect the generation of these irregularities in a way that is not yet fully understood. To improve the forecasting of this phenomenon, we need to study the ionosphere in different regions of the world, and in particular in the equatorial ionization anomaly (EIA) where irregularities are usually more intense. This study analyses the effect of geomagnetic storms on ionospheric irregularities. We examined the occurrence of irregularities at the southern crest of the EIA in Argentina (Tucumán, 26.9°S, 294.6°E, dip latitude 15.5° S) during three intense and one moderate geomagnetic storm of different solar sources, between 2015 and 2018. We used data from an ionosonde, a Global Positioning System (GPS) receiver and magnetometers. Ionogram spread-F, the F-layer bottom side (h'F), the critical frequency of the F2-layer (foF2), the rate of TEC index (ROTI) and the S4 scintillation index were analysed. The data show irregularities were present as range spread-F and moderate TEC fluctuations in one storm: 27 May 2017 (a coronal mass ejection CME-driven storm occurred on local winter), and were absent in the other events. We suggest that eastward disturbance dynamo electric field and over-shielding prompt penetration electric fields may create favourable conditions for developing these irregularities. Whereas, westward storm time electric fields might inhibit the growth of irregularities during the other storms considered. During co-rotating interaction region CIR-driven storms, the westward disturbance dynamo electric field may be associated with the non-occurrence of irregularities.