Atmospheric Chemistry and Physics www.atmos-chem-phys.net 1680-7316 1680-7324 8 11 2008 10.5194/acp-8-2847-2008 http://www.atmos-chem-phys.net/8/2847/2008/ http://www.atmos-chem-phys.net/8/2847/2008/acp-8-2847-2008.html http://www.atmos-chem-phys.net/8/2847/2008/acp-8-2847-2008.pdf 2847 2857 2008-06-04 Variability of the total ozone trend over Europe for the period 1950–2004 derived from reconstructed data J. W. Krzyścin jkrzys@igf.edu.pl J. L. Borkowski Institute of Geophysics, Polish Academy of Sciences, Warsaw, Poland The total ozone data over Europe are available for only few ground-based stations in the pre-satellite era disallowing examination of the spatial trend variability over the whole continent. A need of having gridded ozone data for a trend analysis and input to radiative transfer models stimulated a reconstruction of the daily ozone values since January 1950. Description of the reconstruction model and its validation were a subject of our previous paper. The data base used was built within the objectives of the COST action 726 "Long-term changes and climatology of UV radiation over Europe". Here we focus on trend analyses. The long-term variability of total ozone is discussed using results of a flexible trend model applied to the reconstructed total ozone data for the period 1950–2004. The trend pattern, which comprises both anthropogenic and "natural" component, is not a priori assumed but it comes from a smooth curve fit to the zonal monthly means and monthly grid values. The ozone long-term changes are calculated separately for cold (October–next year April) and warm (May–September) seasons. The confidence intervals for the estimated ozone changes are derived by the block bootstrapping. The statistically significant negative trends are found almost over the whole Europe only in the period 1985–1994. 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