Study of frequency and vertical wavenumber spectra of wind velocity flucutations due to atmospheric gravity waves

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We have reviewed in this study recent observational studies on gravity wave characteristics, focussing on their excitation, propagation aud dissipation proccsses. Since gravity waves are normally observed as superpositioning of many components with different frequencies and wavenumbers, we employed a spectral analysis of wind velocity and temperature fluctuations, obatined with an MST radar, rocketsonde and radiosondes. It has been found that a linear saturation theory of gravity waves sucessfully explained fundamental characteristics of gravity waves, such as height variations of energy and dominant wavelengths.We also delineated latitudinal variations of gravity wave activity through comparative studies between the MU radar at Shigaraki (35ﾟN, 136ﾟE), MF radars at Adelaide (35ﾟS, 139ﾟE) and Saskatchewan (52ﾟN, 107ﾟW). Comparisons were further extended to equatorial regions, by including radiosnde measurements in East Jawa, Indonesia (7ﾟS, 113ﾟE).