Electron temperature control of PMSE

Abstract

Recently an artificially induced modulation of polar mesosphere summer echos (PMSE) was observed when the electrons at PMSE altitudes were heated by a ground based heating facility [Chilson et al., 2000]. The PMSE disappeared within a few seconds when the heater was switched on and reappeared within a few seconds when the heater was switched off again. We explain these observations employing a model of electron diffusion in the environment of positive ions and negatively charged aerosols which takes into account enhanced electron temperatures. If the electron temperature equals the neutral gas temperature, electron diffusion is efficiently inhibited due to the multipolar electric field between the aerosols, positive ions, and electrons. If the electron temperature is enhanced, however, the electron diffusivity is increased which compensates the effect of charged aerosols such that spatial structures in the electron gas at scales as small as the radar half wavelength are efficiently destroyed by diffusion. Furthermore, an enhanced electron temperature increases the aerosol charge which supports the decay of electron disturbance through plasma interference effects. The heating experiment has demonstrated that the reduction of electron diffusivity by charged aerosol particles is the underlying physical mechanism for the existence of PMSE.