First Lidar Observations of Middle Atmosphere Temperatures, Fe Densities, and Polar Mesospheric Clouds Over the North and South Poles

An Fe Boltzmann temperature lidar was used to obtain the first measurements of middle atmosphere temperatures, Fe densities, and polar mesospheric louds (PMCs) over the North and South Poles during the 1999-2000 summer seasons. The measured temperature structure of the mesopause and lower thermosphere regions in mid-summer at both Poles is consistent with the MSIS90 model. The density profiles of the normal Fe layer between 80-100 km at summer solstice are similar at both the North and South Poles with maximum densities of about 2000 cm -a. Sporadic Fe (Fes) layers were observed at both Poles with peak densities at 106 km altitude. The maximum densities of the Fes layers were 232x10 a cm -a at North Pole and 6.52x10 a cm -a at South Pole. PMCs were detected above both Poles. The altitudes of PMCs over the South Pole were consistently 2-3 km higher than those observed over the North Pole.