Surface Ozone Spatial Distribution and Trends Over Europe During 1997–2006
Surface ozone mixing ratio spatial distribution over Europe was constructed through kriging interpolation based on EMEP ground measurements during 1997–2006. The climatology, the annual and seasonal trends, the diurnal cycle and the altitude dependence were studied as well as the relation with the North Atlantic Oscillation (NAO). The mean seasonal cycle amplitude and maximum display an increasing gradient from northwest to southeast, with high levels in Austria and eastern Mediterranean. Trends are close to zero (−1.00 to +1.00 ppbv.year−1), except for significant positive values in UK, Slovakia, S. Scandinavia and Austria, in winter and autumn. Diurnal amplitude decreases with latitude for low altitude stations (<1,000 m), due to enhanced photochemistry, with maximum in the afternoon. Elevated continental stations, usually in the free troposphere, exhibit diurnal variability close to zero and maximum around midnight. In winter about 40% of near surface ozone variability at the western edge of Europe may be attributed to circulation changes and ozone precursors’ transport related to NAO.
KeywordsNorth Atlantic Oscillation North Atlantic Oscillation Index Surface Ozone Diurnal Variability Ozone Precursor
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