[P-EM12] Coupling Processes in the Atmosphere-Ionosphere System

[PEM12-35] On the charging of dust particles in the mesosphere

*Ingrid Brigitte Mann¹、Isabel M. S. Nerland¹、Adrien Pineau³、Herman Larsen Greaker²、Yoshihiro Yokoyama¹ (1.Dept. of Physics and Technology UiT, The Arctic University of Norway, Tromsoe, Norway、2.Andøya Space, Andenes, Norway、3.Laboratory for Laser Energetics, University of Rochester, Rochester, New York, USA)

キーワード：dust, polar mesospheric clouds, mesosphere / lower thermosphere, ionosphere

Dust particles in the mesosphere and lower thermosphere are often electrically charged. The origin of the refractory dust in the mesosphere lies in cosmic dust material left behind in the upper atmosphere by meteoric processes and possibly also in space debris. In addition, ice particles form during the summer months at altitudes close to the mesopause and at middle and polar latitudes. They are observed in polar mesospheric clouds, which are also called noctilucent clouds. The ice particles also play a role in the formation of polar mesospheric summer echoes that are observed with radar as a result of charge interactions. The surface charge is also an important parameter for the growth of dust in mutual collisions and for the condensation of ice particles; and it influences the charge balance in the mesosphere when the number densities of charged dust are of similar order as those of the electrons and ions. The charging processes depend on the dust size and composition, ionospheric conditions and solar radiation. We investigate the charging taking into account the collection of ambient electrons and ions, photo ionisation and photo detachment. We compare the resulting charge distributions for different materials and investigate the influence of the prevailing dust size distribution.