Propagation of Small-Scale Acoustic-Gravity Waves in the Venus Atmosphere

Abstract

The amplification and attenuation of small-scale acoustic-gravity waves in Venus's atmosphere is studied with a plane-wave model that realistically simulates height variations in structure and zonal circulation. Forcing for these waves could be convective activity at cloud heights or close to the surface, or turbulence arising from small-scale shear instability of the zonal flow; the model treats both surface forcing and cloud-level forcing by diabatic heating variations in the low-stability layer near the base of the clouds. Waves are attenuated in this cloud-level, low-static-stability layer. Slowly moving waves with small vertical length scales are attenuated by eddy diffusivity. Westward moving waves can undergo critical level absorption. A net enhancement in wave amplitude is ago possible because waves can be trapped between the surface and the base of the low stability layer at about 50 km. Observations of small-scale wave activity at the cloud tops and above can be used to explore uncertain aspects of atmospheric structure and circulation such as the persistence or decay of the atmospheric superrotation with height above the clouds.