Wave-mean flow interaction and the baroclinic adjustment hypothesis

It has been hypothesized that baroclinic waves interact with the zonally averaged flow in such a way as to eliminate the baroclinicity of the zone and thus the source of instability. In the context of quasigeostrophic theory this amounts to the elimination the pseudopotential vorticity gradient bar Qy via adjustments in the vertical shear, the static stability, or both. Strictly speaking baroclinic neutralization can occur simply by eliminating the temperature gradient at the ground. Gutowski, however, shows that the minimal (i.e., with respect to changes in the zonal available potential energy) adjustment required to stabilize the flow is that where bar Qy vanishes at the surface and in a finite layer above the surface. This is the baroclinic adjustment hypothesis