A parameterization for the effects of ozone on the wave driving exerted by equatorial waves in the stratosphere

Abstract

An equatorial b-plane model of the tropical stratosphere is used to examine the effects of ozone on Kelvin, Rossby-gravity, equatorial Rossby, inertia-gravity, and smaller-scale gravity waves. The model is composed of coupled equations for wind, temperature, and ozone volume mixing ratio, which are linearized about a zonally averaged background state. Using the Wentzel-Kramers-Brillouin (WKB) formalism, equations are obtained for the vertical spatial scale, spatial damping rate, and amplitude of the waves. These equations yield an analytical expression for the ozone-modified wave driving of the zonal-mean circulation. The expression for the wave driving provides an efficient parameterization that can be implemented into models that are unable to spontaneously generate the ozone-modified, convectively coupled waves that drive the quasibiennial and semiannual oscillations of the tropical stratosphere. The effects of ozone on the wave driving, which are strongly modulated by the Doppler-shifted frequency, are maximized in the upper stratosphere, where ozone photochemistry and vertical ozone advection combine to augment Newtonian cooling. The ozone causes a contraction in spatial scale and an increase in the spatial damping rate. In the midstratosphere to lower mesosphere, the ozone-induced increase in wave driving is about 10%-30% for all wave types, but it can be as large as about 80% over narrow altitude regions and for specific wave types. In the dynamically controlled lower stratosphere, vertical ozone advection dominates over meridional ozone advection and opposes Newtonian cooling, causing, on average, a 10%-15% reduction in the damping rate. © 2012 American Meteorological Society.