Experimental and theoretical investigations of the summer and winter mesosphere, with special emphasis on the role of charged dust particles

The Earths mesosphere contain some intriguing phenomena such as the noctilucent clouds (NLC), the highest clouds in the atmosphere near the coldest region in it, and the radar clouds PMSE and PMWE which occur in the summer and winter in different height r egions. It appears that the strength of the PMSE clouds increase and that they appear steadily further south and it is speculated if this can be linked to climatic changes. We have made significant discoveries related to the radar cloud phenomena in c ombined theoretical and experimental investigations and most recently showed that PMWE is, surprisingly, almost certainly influenced by very small dust particles, most likely meteoric smoke particles. In the project period we will make full use of our n ew 56 MHz radar at the Tromsø EISCAT site to investigate, together with the EISCAT radars and Heating Facility, the mesosphere and its dust content with our new overshoot technique. We will in particular investigate if the behavior of the PMWE can give information on the mesospheric global circulation system.