The effect of small-scale inhomogeneities on ozone depletion in the Arctic

Abstract

THE chemical processes involved in the depletion of polar stratospheric ozone are now fairly well understood1,2. But the effect of small-scale stirring and mixing of the chemical species involved can be misrepresented in three-dimensional chemical-transport models because of their coarse resolution. Because of the non-linearities in the chemical rate laws, especially those involving chlorine in the main catalytic cycle, these effects can be important—particularly in the Arctic, where the polar vortex is less uniform and less isolated from surrounding air than in the Antarctic. Here we use a very-high-resolution model with simplified ozone-depletion chemistry to show that the depletion is sensitive to small-scale inhomogeneities in the distribution of reactant species. Under the conditions of the winter of 1994–95 the effect is large enough to account for the observed discrepancies of about 40% between modelled and observed ozone depletion in the Arctic environment3–5.