Do fast gravity waves interact with geostrophic motions?

This paper shows that the rapid, inertia-gravity oscillations present in all numerical integrations of nonlinear rotating fluid systems have no effect on the slower, quasi-geostrophic, oscillations, at least to leading order in Rossby number. This result is confirmed numerically with reduced-gravity two- and one-layer initial value problems with Laplacian or biharmonic frictions. Differences between these findings and those from theoretical turbulence are discussed; these are probably due to the frictional terms, which are active in the numerical calculations here and act to damp out the enstrophy cascade.