Artificial Electron Heating Effects on the Radar PMSE Phenomenon and the Effect of Electron Bite-Outs

Summary form only given. When the temperature near the polar mesopause gets colder than 150degK during summer, dust particles, in particular ice crystals, nucleate at the mesopauses and manifest themselves in two related phenomena known as PMSE and NLC. They are not only interesting phenomena on their own right; they may also be important indicator of impacts caused by humans on our atmosphere. It has recently been shown (Chilson et al, 2000) that PMSE can be reduced in strength by applying the EISCAT heating facility to heat electron during the observation of PMSE. With a repeated heater pattern with the heater on and off for equally long time which was between (10-20) sec. Havnes et al., (2003) demonstrated that if the EISCAT heater was applied in a different pattern with 20 sec on and 160 sec off, to let the plasma relax to the pre-heating level one could observe a PMSE overshoot effect from which one also could extract the heated electron temperature in the PMSE region. We will present a model which includes the effect of dust on the heated electron temperature as a function of height. The dust can influence strongly the electron density since it acts as a sink for the plasma. In many cases this absorption can produce strong local reductions of the electron density, the so called ´electron bite-outs´. We compare the observed overshoot with the electron heated temperature profile, as a function of height