A Mechanistic Model of Ozone Transport by Planetary Waves in the Stratosphere

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  • 1 Department of Atmospheric Sciences, University of Washington, Seattle 98195
  • | 2 National Center for Atmospheric Research, Boulder, CO 80307
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Abstract

The role of planetary-scale waves in the transport of ozone in middle and high latitudes is studied with a linearized model which takes into account the coupling between radiation, chemistry and dynamics. The governing equations are a quasi-geostrophic potential vorticity equation and a continuity equation for perturbations of the O3 mixing ratio. These equations include the effects of absorption of solar radiation by O3, temperature-dependent O3 photochemistry and advection of O3 by wave motions. Model runs show that, with a basic state representative of winter conditions, ultralong waves can produce O3 perturbation which exhibit a phase shift of nearly 180° between the lower stratosphere (where the O3 perturbations are controlled by advection) and the upper stratosphere (where they are controlled by photochemical processes). This phase shift brings the O3 perturbation into phase with the eddy meridional velocity (and 180° out of phase with the eddy vertical velocity) at ∼45 km, giving rise to large poleward and downward zonally averaged transports. The effect on these transports of varying a number of basic-state parameters, such as mean meridional gradient of O3 and temperature dependence of the O3 reaction rates, is also discussed.

Abstract

The role of planetary-scale waves in the transport of ozone in middle and high latitudes is studied with a linearized model which takes into account the coupling between radiation, chemistry and dynamics. The governing equations are a quasi-geostrophic potential vorticity equation and a continuity equation for perturbations of the O3 mixing ratio. These equations include the effects of absorption of solar radiation by O3, temperature-dependent O3 photochemistry and advection of O3 by wave motions. Model runs show that, with a basic state representative of winter conditions, ultralong waves can produce O3 perturbation which exhibit a phase shift of nearly 180° between the lower stratosphere (where the O3 perturbations are controlled by advection) and the upper stratosphere (where they are controlled by photochemical processes). This phase shift brings the O3 perturbation into phase with the eddy meridional velocity (and 180° out of phase with the eddy vertical velocity) at ∼45 km, giving rise to large poleward and downward zonally averaged transports. The effect on these transports of varying a number of basic-state parameters, such as mean meridional gradient of O3 and temperature dependence of the O3 reaction rates, is also discussed.

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