Lidar observations of mesospheric sodium over Italy

We have developed a lidar system for the measurements of the mesospheric atomic sodium (Na) number density profile. The performances and the main characteristics of the system are evaluated showing the first observations: Na number density profiles can be obtained with a resolution of 300 m in altitude and of 200 s in time, the relative uncertainty is between 5% and 10%. These features also allow to discuss the capability of the system to detect the time and space Variability of Na density profiles, which is typical of the gravity wave propagation. The preliminary analysis of the sodium profile dynamics along a 7 hours measurement session, started from 19:30UT on 10 April 1997, shows the presence of wave-like perturbations with characteristics typical of propagating gravity waves.