Ionospheric and Thermospheric Response to the 13 June 2022 M-Class Solar Flare

Abstract

On 13 June 2022, an M3-class solar flare erupted at 03:00 UT that lasted nearly eight hours, causing increased ionization and shortwave radio blackouts. Here, we combine measurements made by the NASA Ionospheric Connections Explorer (ICON) mission to assess the evolution of the ionosphere-thermosphere system in response to this flare. We find that increased solar extreme ultraviolet (EUV) radiation during the flare did increase O⁺ plasma in the region that was directly exposed to the flare, but this effect was moderated by thermospheric perturbations as evidenced by a decrease in column O/N₂ (ΣO/N₂) that accompanied the sequence of events. Larger increases in O⁺ were seen in the same region the day after the flare as the non-impulsive, long-term solar EUV irradiance continued to increase and the thermospheric ΣO/N₂ recovered. When energetic particles arrived 3 days after the event, the ionospheric impact was delayed by about a day compared to the thermospheric changes. Changes in ΣO/N₂ inferred from far ultraviolet airglow are also strongly correlated with relative changes in atomic oxygen independently determined by simultaneous ICON measurements of EUV airglow. These results demonstrate the magnitude, duration, and complexity of change that even moderate M-class flares can generate in the ionosphere and thermosphere.