Numerical Experiments on the Steady-State Meridional Structure and Ozone Distribution in the Stratosphere

Abstract

A two-dimensional circulation model of the stratosphere, incorporating the mutual interrelationships between radiation, photochemistry, and seasonal transport processes, was run under steady-state assumptions to study seasonal variations. The large-scale, quasi-horizontal eddy processes were parameterized in terms of time-zonal mean temperature and ozone mixing ratio using the generalized diffusion formulation on a sloping surface. The computed distributions of temperature and ozone mixing ratio in the meridional plane show satisfactory agreement with the observations in different seasons, thus accounting for the considerable discrepancies between the radiative-photochemical equilibrium state and observations. The significant jetlike features such as westerlies in winter and tropical easterlies in summer are well-reproduced in the upper stratosphere. As a consequence of the generalized diffusion, the mean meridional motions developed the two-cell structure typical of that found in recent observational studies of the winter lower stratosphere. Quasi-horizontal eddies and mean meridional motions contributed significantly to heat and ozone budgets, whereas the vertical eddies had little effect except to transport ozone downward in the winter lower stratosphers.