Radar observations at very high latitudes have revealed the existence of a region of enhanced backscatter in the polar summer mesosphere. This region of the atmosphere is the coldest place on earth and is the location at which the highest clouds on earth are observed: arctic noctilucent clouds. In a previous NSF-funded study, the PI of this proposal has put forth the theory that the enhanced radar echoes are charged aerosols and that these particles are drifting slowly downward analogous to snow. Although not accepted, the PI will continue to investigate this idea by studying in more detail the manner in which the charged aerosol model can account for the radar observations. Furthermore, the PI will address specifically the question of the association between arctic noctilucent clouds and these enhanced radar echoes in the polar summer mesosphere.
