The Turbulent Gravity Wave-Critical Level Evolution of Atmospheric Flow.

Strong turbulence may be produced when an internal gravity wave encounters a critical level. This turbulence can dissipate the wave motion, so that the momentum transported by the wave is deposited into the mean flow. Thus, gravity wave-critical level encounters are a significant mechanism by which the wind may be modified by gravity waves. Such an encounter has been computed. The rms turbulent velocities are seen to be a substantial fraction some 25 of the wave-induced velocity. The absorption of the wave is seen to alter the wind profile, with turbulence distributing the wave momentum flux above and below the critical level. A variety of features of the wave and turbulence motion may be extracted. One which will be useful for comparison with radar observations is the refractive index structure function C sub n - squared and contour plots are displaced. Several other quantities depicting the evolution of the encounter also are presented. Plans for a detailed analysis of these and new computations are outlined. Also discussed are comparisons of these calculations with Doppler radar observations and laboratory measurements.