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.