Sudden enhancement in high-frequency absorption is a well-known impact of solar flare-driven Short-Wave Fadeout (SWF). Less understood, is a perturbation of the radio wave frequency as it traverses the ionosphere in the early stages of SWF, also known as the Doppler flash. Investigations have suggested two possible sources that might contribute to it’s manifestation: first, enhancements of plasma density in the D-and lower E-regions; second, the lowering of the F-region reflection point. Our recent work investigated a solar flare event using first principles modeling and Super Dual Auroral Radar Network (SuperDARN) HF radar observations and found that change in the F-region refractive index is the primary driver of the Doppler flash. This study analyzes multiple solar flare events observed across different SuperDARN HF radars to determine how flare characteristics, properties of the tr...

This study uses multiple ground and satellite-based measurements to investigate the extreme ionospheric response to the Mother's Day storm on May 10–11, 2024. Prompt penetration electric field caused a significant enhancement in the ionospheric vertical drift (∼ 95 m/s) and the equatorial electrojet strength (∼ 275 nT) over Jicamarca. These extreme eastward electric field perturbations, along with the large meridional wind, significantly altered the F-region plasma fountain at different local times. The afternoon equatorial ionization anomaly (EIA) not only sustained for an exceptionally long duration (∼12 hr) but also expanded spatially over time. The separation between the two peaks of EIA crests exceeded ∼48° and ∼70° in the morning and evening sectors, respectively. This study shows, for the first time, that unusually strong EIA can not only develop at different local t...