Stochastic Parameterization of Gravity Wave Stresses

Abstract

Selective transmission of gravity waves into the upper mesosphere and lower thermosphere leads to the generation of mean flows opposite to those below. This interaction is addressed in the context of a simplified transient, stochastic, conservative wave model. The dominant phase speed in the spectrum appears to determine the magnitude of the upper level flow, while the height of interaction is determined by the forcing amplitude. Observed features of the upper atmosphere are efficiently explained by this model, and the results compare very well to recent steady wave models, despite the differing formulations. The model also provides a tentative explanation of the semiannual oscillation in the tropical upper mesosphere.