Gravity Wave Effects and Their Parameterization in Global Models (Invited Presentation)

The issue of gravity wave effects on the zonal-mean circulation in the atmosphere will be reviewed at a tutorial level, with a focus on the non-orographic waves thought to be most important for the mesosphere and upper stratosphere. The evidence indicating that relatively small-scale waves must play an important role in the zonal-mean zonal momentum budget of the middle atmosphere will be reviewed. Then the basic ideas behind current efforts to parameterize the momentum flux associated with gravity waves will be described, along with some practical issues involved in successfully implementing such parameterization schemes. Finally some suggestions for making further progress in this challenging area will be offered.