The effect of ice particles on Thomson scattering from the polar summer mesopause region

In the polar summer mesopause, negatively charged ice particles probably occur forming clouds with a thickness of a few kilometers. It is assumed that colliding ice particles and neutral molecules behave like rigid elastic spheres. Then calculated Thomson scatter spectra have a narrow particle line in addition to the ion and electron lines. Least‐squares fits of theoretical autocorrelation functions to autocorrelation functions measured by the EISCAT 933‐MHz radar yield particle radii and concentrations of about 3 nm and 1010 m−3. These results support earlier suggestions that there is a large number of particles producing electron density depletions and a viscous‐convective subrange in the turbulence spectrum of the electrons.