Quasi-linear theory of interactions between internal gravity waves and shear flows

Resonant interactions between a packet of internal gravity waves (IGWs) with a wide quasi-noise spectrum and a wind shear flow are considered. It is shown that allowance for a nonstationary field of the wave packet leads to a significant disturbance of atmospheric density near the critical layer, where the horizontal phase velocities of the waves forming the packet are close to the velocity of the background wind flow. In a quasi-linear approximation, an analytic solution is obtained for the density disturbance in the case of large Richardson numbers. It is found that resonant interactions between IGWs and a wind flow can be responsible for short-term variations in the density of ozone and other atmospheric constituents even at relatively small IGW amplitudes typical of stratospheric altitudes.