A modeling study of the influence of large-scale wave transport on stratospheric trace gases.

Conventional zonally averaged two dimensional models must parameterize the effect of waves. The parameterization is a significant source to uncertainties in the 2D model simulations. An improved 2D model is developed in this dissertation study by coupling a linearized, quasi-geostrophic potential vorticity equation to a 2D model. Planetary waves are forced by observed daily geopotential perturbations near the tropopause. Unlike 2D models, eddy fluxes induced by planetary waves in the coupled model can be calculated explicitly and the interaction between wave and zonal mean state is allowed. The coupled model reproduces climatological features more realistically than the original 2D model. The relationship between variation of planetary wave forcing and stratospheric ozone change is investigated with the improved model. Simulated interannual variation of the zonal mean temperature is quite close to the observations. The results indicate that stratospheric ozone has a close relationship with planetary wave activity. Ozone variations during winter and spring in both hemispheric are significant. The column ozone changes by up to 15% in the Northern hemisphere winter and spring; the change reaches 6% around 60$\sp\circ S$ from September to November; but the change in the equatorial region is around 1%. The ozone change is consistent with the variation in planetary wave activity. The sensitivity of stratospheric trace gases to the formulation of eddy transport in the coupled model is examined. A three dimensional transport algorithm driven by wind fields from the coupled model is used to study the impact and limitations of the parameterization of wave transport in the 2D model. This study shows that both quasi-conservative trace gases like N$\sb2$O and photochemically active tracers like O$\sb3$ are sensitive to eddy transport. Planetary wave activity induces three processes that affect the distributions of stratospheric trace gases. One is that waves transport trace gases directly; the second is that trace gases respond to changes in the temperature and the residual circulation; the third is that coupling among chemical perturbations induced by wave activity. All three processes are discussed. This study shows that the chemical perturbation coupling plays a significant role in redistributing ozone.Ph.D.Physics, Atmospheric SciencePure SciencesUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/130168/2/9712128.pd