A METHOD FOR THE COMPUTATION OF NORMAL MODE DISPERSION CURVES OF ATMOSPHERIC GRAVITY WAVES IN WINDY ATMOSPHERES

摘要

The multilayer approximation previously used to study propagation in wind-free atmospheres is extended to include winds. Two generalized acoustic potentials are defined. These are continuous even at horizontal discontinuities in wind velocity or sound speed, and the residual equations which these quantities satisfy are derived. Two dispersion functions are defined. Their roots give the phase velocity magnitude and phase velocity direction for normal mode waves propagating with given frequency and given group velocity direction. The multilayer approximation is introduced for computing these dispersion functions by approximating continuously stratified atmospheres with models consisting of a finite number of layers, each with constant wind velocity and sound speed. Numerical methods for finding the roots of the dispersion function are discussed. The theory is then applied to an example of a multilayered atmosphere.