On the ionospheric effects of 26 June, 1999 solar flare

In this paper we traced the possible influence of the solar flare of June 26, 1999 on the ionosphere throughout the F2-layer parameters. This study concentrated on two parameters, foF2, the critical frequency of the ordinary component of the F2-layer; and hc, the height of the maximum obtained by fitting a theoretical h′F curve for the parabola of best fit to the observed ordinary mode trace near foF2 and correcting for under-lying ionization. The results showed that the relation between the amplitude of averaged sudden enhancements of the perturbations for the critical frequency of the ionospheric F2 region, ΔfoF2 (for data obtained from 8 ionosonde stations), and the duration of the flare is more applicable to the empirical formula given by Youssef (2008). Since we found this relation is linear and has a very strong correlation. In addition, we found that the relation between the average amplitude, of ΔfoF2, for the 8 selected ionosonde stations, and the flare flux is not a linear. For the second parameter, hc, it was found that, the hc amplitude depends on the location of the station on the Earth, and it reaches its maximum value during the decay phase of the studied flare.