Ionospheric Electron Concentration Enhancement during a Solar Flare

Abstract

DURING solar flares, sudden increases of extreme ultraviolet (EUV) and X-ray flux produce abrupt increases of electron concentration (Ne) in the sunlit part of the ionosphere. Because of their relatively short duration and the accompanying blackout in h.f. propagation, these enhancements of Ne have hitherto been difficult to investigate, especially in the E region. We report here some results of applying a new technique, incoherent scatter radar, to this problem. The observations were made at Malvern (52.1° N, 2.3° W) during a solar flare on February 20, 1970.