Dependence of the ionospheric response on the solar flare parameters based on the theoretical modeling and GPS data

The measurements of an increase in the total electron content (TEC) of the ionosphere during solar flares, obtained based on the GPS data, indicated that up to 30% of TEC increments corresponded to the ionospheric regions above 300 km altitude in some cases, and TEC increased mainly below altitudes of 300 km in other cases. The theoretical model of the ionosphere and plasmasphere was used to study the obtained effects. The altitude-time variations in the charged particle density in the ionospheric region from 100 to 1000 km were used depending on the solar flare spectrum. An analysis of the modeling results indicated that an intensification of the flare UV emission in the 55–65 and 85–95 nm spectral ranges results in a pronounced increase in the electron density in the topside ionosphere (above 300 km). The experimental dependences of the ionospheric TEC response amplitude on the localization and peak power of flares on the Sun in the X-ray range, obtained based on the GPS data, are also presented in the work.