Radiative forcing of stationary planetary waves

Abstract The stationary wave components of the planetary-scale circulation are maintained by topographic forcing and by latent and sensible heat transfers and radiation. These waves have a potential vorticity balance mainly due to vertically differential thermal advection, advection of planetary vorticity, heating, and topographic convergence or divergence. To elucidate the role of solar and longwave transfers in maintaining stationary planetary waves, the potential vorticity equation appropriate to these disturbances in the middle latitudes of the Northern Hemisphere during winter is solved with realistic radiation physics included in the heating term. A series of experiments with the model isolates the roles of the various optically active constituents in maintaining the stationary planetary waves. Clouds and the net radiative heating tend to amplify stationary planetary wavenumber 1 by increasing the forcing asymmetry, but destructive interference between radiative beating and other diabatic processes ...