First mesopause temperature profiles from a fixed southern hemisphere site

Abstract

The INPE sodium lidar was recently modified so as to enable measurements to be made of the Doppler temperature of the Na atoms in the atmospheric sodium layer. Measurements have been made on a total of 15 nights from July to October, 1998, providing temperature profiles between heights of about 83 and 105 km. Almost all measurements showed a mesopause temperature structure strongly perturbed by oscillations which appear to be caused by gravity waves and/or tides, with peaks in sodium density occurring at almost the same height as the temperature maxima on the bottom side of the sodium layer. The lowest temperatures, between 170 and 200 K, typically occur above 100 km, and the average profile for all our measurements is similar to the winter profile seen at mid‐latitudes, with a mesopause temperature of 190 K at 103 km.