A GENERAL-CIRCULATION MODEL SIMULATION OF THE SPRINGTIME ANTARCTIC OZONE DECREASE AND ITS IMPACT ON MIDLATITUDES

Results of the perturbed simulation show a very good agreement with the ozone measurements made during spring 1987. This simulation also shows the development of a high-latitude anomalous circulation, with a warming of the upper stratosphere resulting mainly from dynamical heating. In addition, a substantial ozone decrease is found at mid-latitudes in a thin stratospheric layer located between the 390 and the 470 K θ surfaces. It is attributed to the cooperative effects of chemical depletion at the edge of the vortex in situations where an upward meridional flow is forced by vertically propagating tropospheric motions (the "chemical eddies'), and of the irreversible air mixing between the outer boundary of the vortex and the mid-latitudes. -from Authors