Response of Topside Ionospheric Electron Density During Solar Flares Using 2014–2024 Swarm Satellite Measurements

This paper presents a global statistical investigation into the topside ionosphere electron density response to X‐class solar flares during geomagnetically quiet conditions (Kp 2) using Swarm satellites (462–511 km) data from 2014 to 2024. The International Reference Ionosphere (IRI‐2020) model is used to provide background topside ionospheric electron density information and the percentage deviation between the model and Swarm measurements is computed. Our results show a consistent decrease in topside ionospheric electron density at all latitude regions with the highest decrease reaching −53% in high latitudes. Mid and low latitude regions experienced decreases of −33% and −25%, respectively, over a similar period. The decrease in topside ionospheric electron density during solar flares is believed to be largely due to thermal ionospheric plasma expansion leading to oxygen ions up flow to the plasmasphere.