Full-scale simulation study of the generation of topside ionospheric turbulence using a generalized Zakharov model

We present a full-scale simulation study of the generation of topside electrostatic turbulence observed near the F region peak during ground based ionospheric heating experiments. The study is performed using a generalized Zakharov model. The nonlinear tunneling of electromagnetic waves through the ionospheric layer is attributed to multiple-stage parametric decay and mode-conversion processes. At the bottomside of the F region, electrostatic turbulence excited by the parametric instability results in the conversion of the ordinary (O mode) wave into a large amplitude extraordinary (Z mode) wave propagating through the F peak. At the topside interaction region, the Z mode undergoes parametric decay process that results in the generation of the topside electrostatic turbulence and then conversion process yielding O waves that escape the plasma. This study may explain the observed topside ionospheric turbulence during ground based low duty cycle ionospheric heating experiments where the heater beam is directed far away from the Spitze region.