The role of excited molecular ions in the variation of the E-layer peak height caused by the solar activity

The data obtained by the Kharkov incoherent scatter radar show a monotonous linear decrease of the E-layer peak height (h/sub m/E) in the transition from the low to medium solar activity. Such behavior of the E-layer peak height is accounted for by the influence of oscillation-excited ions O/sub 2//sup +/ on the h/sub m/E variations depending on the level of solar activity. The theoretical dependences h/sub m/E(F/sub 10.7/) are in a good agreement with the experimental data.