Contributions of road traffic emissions to tropospheric ozone on global and regional scale

Abstract

r this reason we investigate the impact of road traffic emissions with the MECO(n) model-system (MESSy-fied ECHAM and COSMO models nested n-times). This model system features an on-line coupling of the regional scale chemistry-climate-model COSMO/MESSy (in one direction) with the global chemistry-climate-model EMAC. New boundary conditions for the dynamical and chemical fields are provided every timestep of the global model. In addition, we are using the same chemistry module MECCA and diagnostic methods on both scales, making our model chain as consistent as possible. To quantify the contribution of the road traffic emissions to tropospheric ozone we use an accounting system of the relevant reaction pathways of the different species from different sources (called tagging method). Due to our consistent model chain we are able to compare our results on the global and the regional scale directly. Therefore we can quantify the effects of the horizontal resolution and analyze, if such increased resolutions are important for detailed ozone diagnostics. We present first results of our simulations focusing on the different effects on the global and the regional scale.