A General Circulation Model is used to simulate the O3 seasonal variations in the Southern Hemisphere at high latitudes. The model reproduces many features of the stratospheric circulation and the ozone distribution.

In particular a very cold and intense polar vortex develops from mid-winter through spring and lasts until early November. The ozone content is minimum in the polar vortex, below 300 Dobsons, in spring. This value is still significantly higher than the amounts near 200 Dobsons recently measured in several Dobson stations in Antarctica. The possible deficiencies of the model photochemistry responsible for this discrepancy are discussed.

The rapid polar ozone increase which follows the final warming is fairly well reproduced by the model. The warming starts in the early November and is associated with an increase of the planetary wave 1 amplitude beyond 60¿ of latitude. The polar vortex follows a westward trajectory which starts from the pole and crosses over the Argentine Islands before vanishing at midlatitudes, in good agreement with observations.