AN EXPERIMENTAL AND THEORETICAL STUDY OF THE ATMOSPHERIC SODIUM LAYER USING A LIDAR SYSTEM (ATMOSPHERIC GRAVITY WAVES, REMOTE SENSING)

Measurements of atmospheric sodium were made using the sodium lidar system at the University of Illinois. These measurements were analyzed, using signal processing techniques, to determine gravity wave effects seen in the data, to estimate the parameters of gravity waves, and to determine the variation in spectral energy with time of the gravity waves using the Wigner distribution. The seasonal and nocturnal variations of the sodium layer over Urbana, Illinois, were measured by calculating the variations in the height, width, and column abundance of the sodium layer during this study. In addition, the seasonal variation of the gravity wave parameters was also observed.; The model of one gravity wave propagating in the sodium layer was extended to include the effects of two gravity waves in the sodium layer and also a gravity-wave/critical-layer interaction in the region of the sodium layer. The two-gravity wave model was shown to agree closely with the data. The gravity-wave/critical-layer model predicted standing waves in the sodium layer which have been reported by other lidar studies.