Interactions between forced planetary waves and stratospheric ozone: A mechanism for affecting tropospheric wave fluxes?

Topographically forced planetary waves generally extend throughout the troposphere and stratosphere and thus provide an important link between these two regions of the atmosphere. Linear equations coupling quasigeostrophic potential vorticity (PV) and ozone volume mixing ratio are used to examine both analytically and numerically the effects of (stratospheric) ozone heating on the vertical structure and zonal-mean transports of PV, heat, and ozone by topographically forced planetary waves. Emphasis is placed on determining how and under what conditions the interactions between topographically forced planetary waves and stratospheric ozone can affect tropospheric wave fluxes.

The quasigeostrophic PV and ozone continuity equations are combined into a single, altitude dependent (planetary) wave equation in which the index of refraction is a function of the basic state zonal-mean distributions of wind, temperature, and ozone. A WKB analysis yields analytical solutions that show the relative importance of Newtonian cooling, ozone advection, and photochemically accelerated cooling in influencing the waves. In particular, it is demonstrated that in the vicinity of critical lines, meridional advection of ozone is the dominant diabatic process, which, under certain conditions, can have an important affect on the tropospheric wave fluxes.

The one-dimensional (in height) problem also is solved numerically for various background configurations of wind, temperature, and ozone. These background states are chosen to represent the variations that could be expected in each season. Moreover, the sensitivity of the results to nonuniform reductions in ozone arising from natural (e.g., volcanoes) and anthropogenic (e.g., chlorofluorocarbons) perturbations also is examined. Implications for changes in the tropospheric circulation will be discussed.