Charged particle observations in the polar mesosphere during the MaCWAVE and DROPPS Programs

Evidence for charged particles in the polar mesosphere has resulted from probe measurements during two NASA-sponsored rocket programs conducted in northern Scandinavia. The MaCWAVE Program included summer launches (July 2002) from the Andoya Rocket Range, Norway, and winter rocket flights (January 2003) from Esrange, Sweden, while the earlier DROPPS Program occurred during July 1999 at the Andoya Rocket Range, Norway. Both summer investigations were coordinated with the European MIDAS Campaign, which involved additional rocket flights as well as measurements by the ALOMAR Observatory and the EISCAT Radar Facility. On each rocket flight, blunt probes obtained fineresolution current measurements associated with impacting charged particles. Recent analyses of the blunt probe data have focused on refining the estimates for particle size distributions, based on trajectory calculations for the surviving impacting particles. Also, we are using the probe current measurements to investigate fine-scale structure and to develop number density values for the charged particles. The results of these studies are considered in this paper.