Possible effect of hyperthermal electrons on the charging of mesospheric dust

It is generally assumed that negatively charged icy dust particles in the mesosphere are charged by the collection of thermal plasma particles. However, there are some indications that there may be a population of hyperthermal electrons in the D-region under auroral activity under certain conditions (e.g. Margot-Chaker and McNamara, Planetary and Space Science 32, 391, 1984). In this brief communication, we speculate on the effect of a hyperthermal distribution of electrons on dust charging, and how this might affect prevailing turbulence scattering theory for polar summer mesophere echoes.

► We speculate on how hyperthermal electrons that may occur in the D-region under auroral activity could affect dust charging. ► If the dust density is smaller than the density of hyperthermal electrons, the dust negative charge could be enhanced. ► Enhancement of the dust negative charge may lead to increases in the Schmidt numbers by factors of about 2–4.