Mid‐ and High‐Latitude Ionospheric Responses to the Mother's Day Super Geomagnetic Storm of 2024 Using VLF Propagation and Satellite Data

The geomagnetic storm of 10–11 May 2024 (G5-level) caused major ionospheric disturbances, providing an opportunity to examine its wide-ranging effects. This study analyzes ionospheric perturbations over mid- and high-latitude regions using Very Low Frequency (VLF) radio signal observations and TIMED/SABER satellite data in both hemispheres. Significant VLF amplitude anomalies were recorded along five paths (NAA-BRN, NAA-ASB, NAA-KIL, NAA-St. Johns, and NAA-Rothera), indicating strong lower ionospheric responses during and after the storm. High-latitude stations (KIL, Rothera) showed marked signal changes on 11 May, while the mid-latitude site (ASB) exhibited delayed peaks on 13 May. The associated solar energetic particle (SEP) event produced noticeable VLF fluctuations about 10 min after onset, particularly evident in high-resolution data. Wavelet analysis confirmed the presence of atmospheric gravity waves (15 s–30 min periods). SABER observations showed enhanced Nitric Oxide (NO) concentrations in the D- and E/F-regions, peaking on 11 May at 85–95 km and 110–130 km altitudes, respectively. These NO increases, caused by energetic particle precipitation, were observed across both hemispheres. Temperature profiles revealed storm-related warming above 95 km and cooling below 90 km in the Northern Hemisphere, linked to Joule heating, NO-induced infrared cooling, and vertical transport. The study highlights the value of combining ground-based VLF and satellite data to understand storm-time ionospheric dynamics, emphasizing hemispheric asymmetries, delayed responses, and regional variability in space weather effects.