ANALYSIS OF WAVE-TURBULENCE INTERACTION.

Abstract

The results of an analytical and numerical calculation of the interaction between an internal gravity wave and a wave-induced turbulence are presented. The initial atmospheric state, assumed horizontally homogeneous, is statically and dynamically stable with the background Richardson number Ri//0 approaching 1/4 over some height regions. An initial non-singular neutral gravity wave propagates through such a system and modifies the Richardson number. The new Richardson number Ri may become smaller than 1/4 and turbulence may develop. using a ″1 1/2th order″ scheme for the turbulence, the mean and the fluctuating part of the eddy diffusion coefficient are calculated. It is shown that the fluctuating part of the diffusion coefficient, because of its amplitude and phase, may overcome the damping effect of its mean part and force the original wave to grow in time. As the wave grows, it may further lower the Richardson number, increase the intensity of the turbulence, and further strengthen its interactionwith it. By showing that the early stages of the wave-induced turbulence interaction can lead to energy being transferred into the wave, the case for gravity waves as important elements in the generation of turbulence in the atmosphere is strengthened.