LAGRANGIAN TRANSPORT CALCULATIONS USING UARS DATA .2. OZONE

Trajectory calculations are used to examine ozone transport in the pol ar winter stratosphere during periods of the Upper Atmosphere Research Satellite (UARS) observations. The value of these calculations for de termining mass transport was demonstrated previously using UARS observ ations of long-lived tracers. In the middle stratosphere, the overall ozone behavior observed by the Microwave Limb Sounder in the polar vor tex is reproduced by this purely dynamical model. Calculations show th e evolution of ozone in the lower stratosphere during early winter to be dominated by dynamics in December 1992 in the Arctic. Calculations for June 1992 in the Antarctic show evidence of chemical ozone destruc tion and indicate that approximate to 50% of the chemical destruction may be masked by dynamical effects, mainly diabatic descent, which bri ng higher ozone into the lower-stratospheric vortex. Estimating differ ences between calculated and observed fields suggests that dynamical c hanges masked approximate to 20%-35% of chemical ozone loss during lat e February and early March 1993 in the Arctic. In the Antarctic late w inter, in late August and early September 1992, below approximate to 5 20 K, the evolution of vortex-averaged ozone is entirely dominated by chemical effects; above this level, however, chemical ozone depletion can be partially or completely masked by dynamical effects. Our calcul ations for 1992 showed that chemical loss was nearly completely compen sated by increases due to diabatic descent at 655 K.