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Introduction

Discovering of the ozone hole in the Southern Hemisphere (Farman et al., 1985) and later on lesser scales in the Northern Hemisphere (Brune et al., 1990) put up a problem of the ozone depletion as one of the major global scientific and environmental issue of the last century. Recent measurements of the tropospheric source gases have shown decreasing in the concentration of CFCs as has been expected according to Montreal Protocol and its Amendments restrictions (Montzka et al., 1996, Montzka et al., 1999, Engel et al., 1998, Froidevaux et al., 2000, Anderson et al., 2000). Anderson et al.(2000) pointed out that the atmosphere is becoming less chlorinated near the stratopause since the beginning of 1997. On the other hand, according to Report on the Fifth European Ozone Symposium (SPARC News, 2000) total ozone values over the Arctic in spring 1998 and 1999 were higher than in the previous few years and almost reached the amounts observed in 1980s. Accordingly, it is important to assess the benefits of the MPA and track its progress in the future (WMO, 1999, SPARC, 1998). This problem cannot be resolved on the base of an analysis of observed ozone trends alone, or by using simple models because the level of ozone in the atmosphere is controlled by many interacting processes, including chemical destruction and production, as well as the changes in temperature and circulation patterns. Even two dimensional (2D) models with enhanced photochemistry can not be used to elucidate this problem because their prescribed by most of the 2D models zonal-mean temperature and circulation does not reproduce interannual variability and does not allow to calculate correctly the appearance of PSC, the main factor which determines the ozone destruction in the high-latitude stratosphere.