The effects of a total solar eclipse that occurred on 2021 December 4 on ionospheric total electron content (TEC) over Antarctic stations were studied. The study was based on GPS data obtained over Antarctica on the day of the eclipse and the days before and after the eclipse over six GPS stations. The findings of this study show that a total solar eclipse lowers the amount of ionization reaching the Earth’s surface with TEC values dropping across the stations. Finally, the enhancement of ΔTEC is quite different from one station to another station. This may also be due to the effect of solar heating conditions and the density of the Sun as exerted over the stations with the Sun side over one station and the clouded part over the others.

In this study, the cosmic ray stuff and its associations with the solar flare index, coronal index, and geomagnetic indices, such as Kp, auroral electrojets, Ap, disturbance storm time (Dst), polar cap, Lyman-alpha, Hp60, and Ap60 indices, were studied using wavelet-based approaches over KIEL and MOSC stations during 2003 and 2004. The cosmic ray data used in this study were obtained from ground-based neutron monitor stations. Different sources are also used to get data on the different indices used in this study. The yearly variation in cosmic ray intensity revealed that the intensity of cosmic rays over KIEL and MOSC stations was greater in 2004 and lower in 2003. This variation might be due to the ring current's asymmetry, which causes an enormous asymmetry in the storm-time cosmic-ray increase. The wavelet coherence transform shows a positive and negative correlation as well as cosmic ray lags with solar flares and coronal indices throughout different months of the 2003 and 2004 periods over both suggested stations. The results of cross correlation indicate that cosmic ray intensity is positively correlated with all geomagnetic indices. However, cosmic ray intensity was negatively associated with the Dst index during 2003 and 2004 over both suggested stations. Moreover, multi-resolution analysis and power spectral density (PSD) analysis are consistent with wavelet analysis. Using the PSD result, we have seen high-power wavelet regions during geomagnetically quiet months and low-power wavelets during disturbed months at a common frequency over both stations during 2003 and 2004.

This study investigates the ionospheric response to a geomagnetic storm triggered by a Coronal Mass Ejection (CME) during 6–9 September 2017, across GPS stations located in diverse geographical regions. We analyze the changes in the magnetic field component (ΔH), the Prompt Penetration Electric Fields (PPEF), and the Total Electron Content (TEC). We find that ΔH exhibits latitude-dependent responses during the storm, with high-latitude stations experiencing more significant reductions compared to low-latitude stations. The PPEF behavior is found to be directly correlated with solar wind disturbances. Particularly during the main phase of the storm, fluctuations in PPEF were clearly associated with negative values in the Dst index. The KIRU station, located at a high latitude, shows the most pronounced PPEF effects, indicating the increased susceptibility of high-latitude regions to solar wind interactions. The time series plot of TEC, covering a full month at different stations, shows a distinct diurnal pattern driven by solar ionization. Equatorial stations such as HYDE, BOU, HON (HNLC), and DODM exhibit the highest daily TEC values. During the geomagnetic storm, TEC disturbances are evident across all stations, with significant disturbances and varying trends in TEC depletion rate observed at different locations. The TEC values differ by 5–25 TECU during the storm period, suggesting intricate ionospheric responses to geomagnetic storms at different stations. This highlights the importance of considering different geographical regions to fully understand the ionospheric dynamics related to solar activities.

This study examines the ionospheric Total Electron Content (TEC) responses to a solar flare on October 28, 2021, and a geomagnetic storm on November 4, 2021, across low, middle, and high latitude regions. We utilized GPS-TEC data from the University NAVSTAR Consortium’s dual-frequency GPS devices at the IFR1, IISC, YIBL, YKRO, KERG, and SVTL stations. While the solar flare on October 28, 2021, triggered the geomagnetic storm on November 4, 2021, our analysis revealed notable TEC changes during the latter event. TEC fluctuations were observed across all stations during the geomagnetic storm, with significant disruptions and variable depletion rates. However, distinct TEC variations were noted at KERG and YIBL stations before the storm, likely due to the preceding solar flare. Continuous wavelet analysis (CWT) showed higher periodicity during the storm compared to the flare, proving CWT to be an effective tool for analyzing TEC variability by revealing periodicity fluctuations at all stations. In conclusion, we found that both solar flares and geomagnetic storms can cause significant positive TEC changes.