Abstract
During a solar flare, fluxes in various lines and continua of the solar spectrum increase, causing enhanced ionisation in the illuminated part of the Earth’s ionosphere and an increase in the total electron content (TEC). The dynamics of TEC driven by the impulsive phase of solar flares have been studied extensively through both modelling and experimental measurements. However, the ionospheric effects of the late phase of solar flares, which occur in nearly half of X-class flares, were discovered only in 2024. This talk presents the results of the first multi-event study of the ionospheric response to the late phase of X-class solar flares. It also investigates how the flare’s location on the solar disk affects the ratio of ionospheric responses between the impulsive and late phases.