Journal Article

D- and F-Region Ionospheric Response to the Severe Geomagnetic Storm of April 2023

Sen, Arnab, Das, Bakul, Mondal, Sushanta K., Pal, Sujay

2025

Overview

This study investigates the impact on the Earth’s ionosphere of a severe geomagnetic storm (Dst ∼ −212 nT) that began on 23 April 2023 at around 17:37 UT according to very low-frequency (VLF, 3–30 kHz) or low-frequency (LF, 30–300 kHz) radio signals and ionosonde data. We analyze VLF/LF signals received by SuperSID monitors located in mid-latitude (Europe) and low-latitude (South America, Colombia) areas across nine different propagation paths in the Northern Hemisphere. Mid-latitude regions exhibited a daytime amplitude perturbation, mostly an increase, by ∼3–5 dB during the storm period, with a subsequent recovery after 7–8 days post April 23. In contrast, signals received in low-latitude regions (UTP, Colombia) did not show significant variation during the storm-disturbed days. We also observe that the 3-hour average of foF2 data declined by up to 3 MHz on April 23 and April 24 at the European Digisonde stations. However, no significant variation in foF2 was observed at the low-latitude Digisonde stations in Brazil. Both the VLF and ionosonde data exhibited anomalies during the storm period in the European regions, confirming that both D- and F-region ionospheric perturbation was caused by the severe geomagnetic storm.

• Publisher: MDPI AG
• Subject: Analysis / Atmosphere, Upper / Charged particles / coronal mass ejection (CME) / Electrons / F region / foF2 / geomagnetic storm / Geomagnetic storms / Geomagnetism / ionosonde / Ionosondes / Ionosphere / ionospheric disturbance / Latitude / Magnetic fields / Magnetic storms / Northern Hemisphere / Perturbation / Propagation / Radiation / Radio signals / Storms / Very Low Frequencies / VLF/LF radio waves