Ionization Properties of the Dusty Mesosphere
Boris A. Klumov, Sergey I.Popel Institute for Dynamics of Geopsheres, Russia
Robert Bingham, Rutherford Appleton Lab, UK
The problem of influence of the dynamics and charging of dust particles on the ionization properties of the polar summer mesosphere is considered. This problem is connected with the problem of explanation of some layered structures in the Earth's upper atmosphere which are known as noctilucent clouds (NLC) and polar mesosphere summer echoes (PMSE). These structures are believed to be associated with the presence of a large amount of charged dust or aerosol in the upper atmosphere. The great interest in these structures is due to their possible connection with Earth's global warming process. We introduce the notion "dusty mesosphere" for the layer of the mesosphere at the altitudes of approximately 80-90 km, where the conditions for the nucleation and formation of macro (dust) particles are fulfilled. We propose the self-consistent model which describes and takes into account nucleation of particles, the growth of dust particles in size, dust particle charging process, ionization, recombination, solar radiation, photoelectric effect, sedimentation, as well as self-consistent electric fields. We calculate spectra of solar radiation at the altitudes corresponding to dusty mesosphere and analyze the possibilities of the formation of dust particle structures^1. The model allows us to explain the most important ionization effects observed in the polar summer mesosphere, in particular, electron and ion depletions as well as the ionization layers. It is shown that these effects are related to the presence of charged dust. We assume to develop the model to describe self-consistently the process of formation of the observed dust structures such as NLC and PMSE.
1. B.A. Klumov, S.I. Popel, and R. Bingham, Dust Particle Charging and Formation of Dust Structures in the Upper Atmosphere, JETP Letters 72, 364-368, 2000