 Linear pressure equation for rotating stratified flow

With downward buoyancy $b=g\rho \prime /{\rho }_0$ in a uniform rotating Boussinesq approximation, $q=\zeta -f{b}_z/N^2$ is time-independent. The linear pressure obeys ${\nabla }^2{p}_{tt}+f^2{p}_{zz}+N^2{\nabla }_H^{2}p={\rho }_{0}f{N}^{2}q$. The initial potential vorticity supplies the steady pressure source; nonzero-frequency inertia-gravity waves have zero perturbation PV.