Pinatubo aerosol and stratospheric ozone reduction: Observations over central Europe

Long-term observations of ozone profiles at Lindenberg (52.2 degrees N, 14.1 degrees E) and of profiles of the particle surface area concentration at Geesthacht (53.4 degrees N, 10.4 degrees E) are evaluated. Six time series of monthly mean ozone anomalies are formed for layers between 13.5 and 27 km height. The effects of seasonal variation, trend, quasi-biennial oscillation (QBO), polar vortex, and North Atlantic oscillation (NAG) are eliminated. The residual anomalies indicate aerosol-induced ozone losses between 10 and 30% in the central part of the Pinatubo layer (15-20 km height) in the winter and spring seasons of 1991-1992 and 1992-1993. Values of the monthly mean particle surface area concentration ranged from 10 to 36 mm(2) m(-3) during this time period. A correlation analysis, based on mean values of the ozone and aerosol data for the lower, central, and upper part of the Pinatubo layer, indicates a weak positive linear relationship between ozone depletion and surface area in each of the three layers. There is a generally strong influence of the polar vortex strength on the ozone concentration in winter. In the winter of 1992-1993, 10 to 60% of the entire ozone reduction is estimated to be related to the anomalously strong polar cyclone. After the elimination of the vortex-induced reduction, winter mean sulfate-related ozone losses of 10 to 20% were associated with winter mean surface area concentrations of 15 to 20 mm(2) m(-3) for the first two winters after the eruption. The observations are compared with other measurements at northern midlatitudes and with model calculations. In general, a good agreement is found.