Active Perturbation of Dust-Associated Electron Irregularities in the Earth´s Mesosphere: Discrete-Charging Effects

Polar mesospheric summer echoes (PMSEs) are strong radar echoes produced by scattering from electron irregularities associated with charged dust in the Earth´s mesosphere. Recent experimental observations have shown that PMSEs can be modulated by radio wave, heating the irregularity source region with a ground-based ionospheric heating facility. This radar-signal modulation shows very interesting and important behavior, which can be used to study the basic physics of the Earth´s mesospheric dusty plasma. Previous works employed continuous-charging models to investigate the temporal behavior of plasma irregularities during ionospheric heating. Due to the relatively small size of the dust grains, the use of a continuous-charging model may certainly be brought into question. This paper describes a new model that incorporates discrete-charging effects, which has been used to investigate the temporal behavior of charged-dust-associated electron irregularities during electron temperature enhancement associated with radio-wave heating. The dust-charge-number distribution evolution during the ionospheric heating is also studied using the discrete-charging model. The discrete model results show reasonably close behavior with the continuous model. The differences between these two models are also discussed.