POSSIBLE CAUSES OF TOTAL OZONE INCREASE IN SOME REGIONS OF THE NORTHERN AND SOUTHERN HEMISPHERES IN 1979–1992

E. A. Zhadin

Mean monthly interannual variations in the total ozone and stratospheric circulation are analyzed to explain the existence of positive total ozone trends over the Labrador in January and south of Africa in July 1979–1992. It is shown that interannual variations in the stratospheric polar vortex over the Arctic have a longitudinal dipole-like structure with an opposite seesaw in the Western and Eastern hemispheres. Positive total ozone trends over the Labrador are linked to the weakening in the rotation of stratospheric polar vortex in the western Arctic in 1979–1992, while its rotation was strengthening in the eastern Arctic, which resulted in a larger isolation of polar vortex in this region and the negative total ozone trends over Eastern Siberia and the Pacific coast of Canada. Relations of the longitudinal asymmetry of interannual variations in the stratospheric polar vortex over the Arctic, stratospheric warmings, Arctic Oscillation index, and the Atlantic and Pacific sea surface temperature are discussed. It is also shown that the positive total ozone trends south of Africa in July 1979–1992 are associated with the long-term variations in the stratospheric circulation at middle and subtropical latitudes of the Southern Hemisphere. The results give evidences of a great contribution of natural factors to the ozone layer variations observed.