W. Fricke

An Empirical, Receptor-Based Procedure for Assessing the Effect of Different Ozone Mitigation Strategies

The paper presents a new receptor-based approach for investigating the effect of different mitigation strategies on surface ozone concentrations. The empirical approach relates measured ozone concentrations to 3-D back trajectories and European precursor emission data (NO x , VOC, isoprene). These are the only parameters used as input. Following a description of the method, results for two German stations, an urban and a rural mountain site, are described, and discussed in detail. For the urban site, precursor reductions of 50% in an area of 0.5 million km2 around the station resulted in ozone reductions between 10 and 22% during a smog episode, and between 9 and 14% for the summer season. This compares well with CTM results. Increasing the area of reduced emissions above 0.5 million km2 does not lead to additional ozone reductions. Application of the procedure to the mountain site gives plausible results if only NO x , only VOC or only isoprene is reduced. However, simultaneous reduction of NO x and VOC leads to an unlikely ozone increase. Possible reasons for this are discussed, and proposals for testing and improving the method are made.