This proposal will continue three more years of the work currently supported by Cooperative Agreement ATM-8714335. The research involves radar observations at the Jicamarca Radio Observatory, which is located near Lima, Peru, and will be conducted by Cornell scientists and students, resident staff members of the Observatory, and visiting scientists and students from other institutions in the United States and other countries. This Cooperative Agreement provides the main financial support for the Observatory. The topics to be investigated include: (1) the energetics and dynamics of the equatorial F region and protonosphere, (2) plasma instabilities in the equatorial E and F regions, (3) mesospheric and stratospheric dynamics and energy transfer processes, and (4) changes in the geomagnetic field.***//