Gravity waves in the upper mesosphere over Antarctica: lidar observations at the South Pole and Syowa

Lidar observations of the mesospheric Na layer were made at the south pole (90°S) and Syowa (69°S) during the winters of 1990 and 1985, respectively. These observations are used to characterize the gravity wave activity in the upper mesosphere at both sites. Strong wave activity is observed throughout the winter at both the south pole and Syowa and shows remarkable similarity with observations from several midlatitude and low-latitude sites. The quasi-monochromatic gravity waves exhibit the same general relationships between their wavelengths, observed periods, and amplitudes as observed at lower latitudes. The average growth length of these waves is approximately 26 km, indicating that the wave field at both Antarctic sites is strongly influenced by dissipation and saturation processes. The spectra and variances of the density perturbations associated with quasi-random wave field at the south pole are reported. The vertical wavenumber and temporal frequency spectra follow power-law shapes. -from Authors