Model prediction of the most effective frequency for the large-scale modification of the midlatitude ionospheric F 2 layer by powerful HF radiowaves

The response of the midlatitude F 2 layer to the effect of powerful HF radiowaves is studied using the numerical model of the ionosphere. The large-scale modification of the F 2 layer over the Sura heating facility near Nizhni Novgorod is considered for autumnal conditions. The calculations are performed for various cases when the heating wave has different frequencies under the daytime and nighttime conditions. The calculation results show that large-scale changes in the electron temperature and density in the F 2 layer caused by the artificial heating should substantially depend on the heating radiowave frequency. It is found that there should exist such, most effective, heating wave frequency at which a decrease in the electron density at the F 2 layer maximum height over the heating facility should be maximal.