On initial enhancement of mesospheric dust associated plasma irregularities subsequent to radiowave heating

Abstract. Important observational manifestations of subvisible mesospheric dust are Polar Mesospheric Summer Echoes PMSE which are produced by scattering from electron irregularities produced by dust charging. It has been observed that the PMSE strength can be artificially modified by using a ground-based ionospheric heating facility to perturb the electron irregularity source region that is believed to produce PMSE. Recently it has become evident that significant diagnostic information may be available about the dust layer from the temporal behavior of the electron irregularities during the heating process which modifies the background electron temperature. Particularly interesting and important periods of the temporal behavior are during the turn-on and turn-off of the radiowave heating. Although a number of past theoretical and experimental investigations have considered the turn-off period, the objective here is to consider futher possibilities for diagnostic information available as well as the underlying physical processes. Approximate analytical models are developed and compared to a more accurate full computational model as a reference. Then from the temporal behavior of the electron irregularities during the turn-off of the radiowave heating, the analytical models are used to obtain possible diagnostic information for various charged dust and background plasma quantities.