Abstract ATM-9419683 Zhu A new approach on the formation of gravity wave spectrum in the middle atmosphere is proposed to investigate the statistical properties of the observed mesoscale fluctuations in the middle atmosphere. A preliminary study has shown that scale-dependent radiative damping of the temperature perturbations in the middle atmosphere is an important process in the understanding of the gravity wave spectrum. Further research on this subject will fully explore the basic idea of a balance among various spectral sources and sinks by including other possibly important physical processes, such as photochemical-radiative coupling, resonant wave-wave interactions, and molecular diffusion, in the model. Our theoretical studies will be implemented in a two-dimensional (latitude and altitude) numerical model. Our model results will be compared to the available observations from the Flatland radar for the nonlinear wave-wave interactions and measurements from aircraft on polar ozone for the vertical mixing. The ultimate objectives are to provide a more realistic parameterization for the gravity wave saturatimn induced eddy diffusion and momentum deposition in the large scale background flow.