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gfdl's home page > gfdl on-line bibliography > 1980: Journal of the Atmospheric Sciences, 37(3), 655-685
Three-dimensional tracer structure and behavior as simulated in two ozone precursor experiments
| Mahlman, J. D., H. Levy II, and W. J. Moxim, 1980: Three-dimensional tracer structure and behavior as simulated in two ozone precursor experiments. Journal of the Atmospheric Sciences, 37(3), 655-685. |
| Abstract: The GFDL, II-level, general circulation-tracer model is used for two experiments designed to prepare the way for a self-consistent model of atmospheric ozone. The first experiment invokes a simple condition at the top model level: an instantaneous relaxation to a specified 10-mb average observed ozone value. The tracer is inert below the top level until it is removed in the lower troposphere. The second experiment introduces a simplified, but reasonably realistic, ozone chemistry at the top level, including Chapman, nitrogen, and hydrogen loss processes. Below the top level, ozone is inert and is removed in the lower troposphere by the same mechanism as in the first experiment. These two experiments, in spite of their different middle stratospheres, show remarkably similar behavior in the lower stratosphere. A comparison of model values and fluxes with available observations shows general qualitative agreement as well as some notable discrepancies. In the second experiment, a detailed analysis of the processes affecting the 10-mb, zonal-mean mixing ratio is presented. The results show that the midstratospheric ozone production and losses are strongly sensitive to circulation features, changing overhead sun angle, and temperature. These various effects lead to some substantial interhemispheric and seasonal asymmetries in ozone production. An analysis of the transport processes is performed, leading to the pronounced poleward-downward slope of tracer isopleths. The results demonstrate that adiabatic and diabatic effects in the eddies, as well as diabatic effects in the zonal mean, all contribute importantly to the creation of these sloping surfaces. As an aid to tracer transport analysis, a Lagrangian nontransport theorem is derived for an integration following a fluid particle. Some Lagrangian drift-type calculations are performed in the model January mean flow. The results show a slow, but substantial, particle convergence just to the cyclonic shear side of the time-mean jet stream axis. This is a region in which the traditional zonal-mean budget analysis shows a large cancellation between eddy and meridional circulation flux convergence. Also, the analysis demonstrates indirectly the important contributions of transient disturbances to the movement of heat and tracers irreversibly into the stratospheric polar vortex. |