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This paper presents a wavelet‐based analysis of ionospheric irregularities induced by three different geomagnetic storms of varying strength and interplanetary origin over three mid‐latitudes stations, viz. Moscow, Fairford, and Rome. We observed the highest decrease in ionospheric variables (foF2, total electron content (TEC), and NmF2) during the negative phase of the G4 storm. Interestingly, hmF2 exhibits the opposite trend in terms of variation. The maximum ionization height (hmF2) for the G4 event is 500 km (during the main phase) and 150 km (during the recovery phase). Within 2–3 hr of the G4 event, the value of hmF2 is found to decline by 70%. The largest reduction (80%) in critical frequency (foF2) is observed during the negative phase of this event, which is also confirmed by the continuous wavelet transform results. During the negative phase, we observed noticeable power shifts in the signal of the ionospheric parameters toward the lower Fourier period band. During the G4 storm—Particularly during the negative phase—The lowest power linked with the ionospheric parameter's signal was discovered. Additionally, we used detrended cross‐correlation analysis to investigate the correlation and time lag between geomagnetic indices (Symmetric H‐component (SYM‐H) & auroral electrojet) and ionospheric parameters (foF2, NmF2, hmF2 & TEC). The significant association between SYM‐H and ionospheric parameters suggests that the magnetosphere‐ionosphere interaction produces intense electric field disturbances and winds in the mid‐latitudes, resulting in the perturbation of hmF2, foF2, TEC, and NmF2. Key Points: During the negative phase of the G4 storm, the highest decrease in ionospheric variables (foF2, total electron content, and NmF2) was seenWe observed noticeable power shifts in the signal of the ionospheric parameters toward the lower Fourier period band during negative phaseThe correlation between the Symmetric H‐component and auroral electrojet indices varies according to geomagnetic storm strength and interplanetary origins [ABSTRACT FROM AUTHOR]

We analyzed the behavior of Cosmic-Ray (CR) intensity during five geomagnetic events over 9-day periods of varying disturbance, using ground-based CR measurements from the Bartol Research Institute neutron-monitor program that occurred on 25th October – 2nd November 2003, 23rd – 31st July 2004, 13th – 21st May 2005, 13th – 21st Mar 2015, and 19th – 27th June 2015. A nine-day time frame gives us a reasonable time interval for data analysis before, during, and after the main event(s). These events have been deliberately chosen, intending to track Forbush Decreases (FDs) at high-latitude stations following geomagnetic storms of different intensity and duration from the perspectives of their origin and geoeffectiveness. FDs are observed when the magnetic fields entangled in and around a Coronal Mass Ejection (CME) exert a deflecting effect on galactic cosmic radiation, resulting in a sudden reduction in their intensities. The results revealed that the CR intensity dropped by 4 – 17% in the chosen events. The FDs examined were not typical, with multistage decrement during the event period. Furthermore, we have used the Discrete Wavelet Transform (DWT) technique to detect a singularity on the CR intensity at the stations described. The first three decomposition levels have proved sufficient to isolate the transients in CR intensity in conjunction with varying nature and intensities, ranging from intense to superintense geomagnetic storms to a high-intensity long-duration continuous auroral electrojet activity (HILDCAA) event. Finally, the findings of the detrended crosscorrelation technique showed a good association of percentage decrease in cosmic-ray intensity with the Dst index during the process. No noticeable lag has been found between the parameters discussed, which indicates a strong correlation between the IMF-Bz and the Dst index and the FD. [ABSTRACT FROM AUTHOR]

The original article can be found online at DOI B Correction to: Solar Physics (2022) 297: 1-24 b https://doi.org/10.1007/s11207-022-01948-z The original publication has been corrected. HT