Abstract
A couple of two-dimensional linear and fully nonlinear numerical models for compressible atmosphere are used to numerically study the propagation of the gravity wave packet into a mean wind shear. For a linear propagation wave packet, the critical level interactions are in good agreement with the linear critical level theory. The dynamically and convectively unstable regions are formed due to the critical level interaction of a finite-amplitude wave packet, but they would not break. The free exchange of potential energy with kinetic energy in the background atmosphere at rest ceases after entering the mean wind shear. However, it still goes on in the nonlinear propagation. It is shown that the nonlinear effects modify the mean flow markedly, reduce the momentum and energy propagation velocity and drop the elevation of the critical level. The gravity wave packet becomes unstable and breaks down into smaller scales in some regions. It expends much more kinetic energy than potential energy in the early phase of the breakdown. This means that the wave breakdown sets up due to the action of the shear instability rather than a convective one.
Similar content being viewed by others
References
Bretherton, F. P., The propagation of groups of internal gravity waves in a shear flow, Q. J. R. Meteorol. Soc., 1966, 92: 466–480.
Booker, J. R., Bretherton, F. P., The critical layer for internal gravity waves in a shear flow, J. Fluid Mech., 1967, 27: 513–539.
Grimshaw, R., Nonlinear internal gravity waves and their interaction with the mean wind, J. Atmos. Sci., 1975, 32: 1779–1793.
Hartman, R. J., Wave propagation in a stratified shear flow, J. Fluid Mech., 1975, 71: 89–104.
Fritts, D. C., The transient critical-level interaction in a Boussinesq fluid, J. Atmos. Sci., 1982, 87: 7997–8016.
Winters, K. B., D’Asaro, E. A., Two-dimensional instability of finite amplitude internal gravity wave packets near a critical level, J. Geophys. Res., 1989, 94: 12709–12719.
Thorpe, S. A., Turbulence in stably stratified fluids: A review of laboratory experiments, Boundary Layer Meteorol., 1973, 5: 95–119.
Thorpe, S. A., An experimental study of critical layers, J. Fluid Mech., 1981, 103: 321–344.
Yi, F., Klostermeyer, J., Ruster, R., VHF radar observation of gravity wave critical levels in the mid-latitude summer mesopause region, Geophys. Res. Lett., 1991, 18: 697–700.
Yi, F., Klostermeyer, J., Ruster, R., VHF radar observation of gravity wave critical layers in the polar summer mesopause region, Ann. Geophys., 1992, 10: 887–894.
Yue, X., Yi, F., A study of nonlinear propagation of 3d gravity wave packets in a compressible atmosphere by using ADI scheme, Chin. J. Space Sci., 2001, 21(2): 148–158.
Yue, X., Yi, F., Liu, Y., Li, F., Numerical study of the propagation of small amplitude atmospheric gravity wave, Chinese Science Bulletin, 2005, in press
Yeh, K. C., Liu, C. H., Acoustic-gravity waves in the upper atmosphere, Rev. Geophys., 1974, 12: 193–216.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Yue, X., Yi, F. Propagation of gravity wave packet near critical level. Sci. China Ser. E-Technol. Sci. 48, 538–555 (2005). https://doi.org/10.1360/102005-24
Received:
Revised:
Issue Date:
DOI: https://doi.org/10.1360/102005-24