THE EFFECT OF DYNAMICAL MIXING IN A SIMPLE-MODEL OF THE OZONE HOLE

The role of the horizontal dynamical mixing on the ozone destruction b y chlorine in the polar stratosphere is investigated. We use a one- di mensional high-resolution model to represent the microstructure of che mical species distribution on which the effective reactivity depends. The chemical model is idealized by only considering two species, ozone and chlorine (assumed to be under the active form Cl0). Ozone destruc tion is proportional to the square of chlorine content. We compare the effects of a chaotic type of mixing, represented as a Bernoulli map o ver the unit interval, with, purely diffusive mixing, which is used in most parameterizations of turbulence. The comparison is done for vari ous values of the chemical reactivity constant. Owing to the nonlinear ity of the chemical reaction, reactivity decreases with mixing if the chemical constant is small, while it increases with mixing for large v alues of the chemical constant. In any situation, large discrepancies in the ozone destruction are observed between chaotic and diffusive mi xing, indicating the need for a better representation of the mixing pr ocesses in studies of stratospheric chemistry.