Observations of mesospheric wind velocities 2. Cross sections of power spectral density for 48–8 hours, 8–1 hours, and 1 hour to 10 min over 60–110 km for 1981

Abstract

Cross sections of power spectral density for 1981 between 60–110 km for the 48- to 8 hour and 8- to 1-hour-period bands, and of mean square velocity components in the 10- to 60-min-period band, are compared to cross sections of mean wind. Individual spectra agree well in form and amplitude to similar spectra for other sites when averaged over the entire year, but there are substantial variations in power spectral density in each band over the year. In the 10-min to 8-hour-period band, minima in spectral densities follow the zero line of mean zonal velocity very closely, indicating strong gravity wave mean flow interactions. This, and the variation in gravity wave intensity in general, suggests that gravity wave momentum deposition plays an important role in balancing the heat and momentum budgets of the upper middle atmosphere.