Impact of road traffic emissions on tropospheric ozone in Europe for present day and future scenarios

Kurzfassung

The road traffic sector is an important anthropogenic source for emissions of NOx, CO and non-methane hydrocarbons (NMHCs) which act as precursors for the formation of tropospheric ozone. The formation of ozone is highly non-linear. This means that the contribution of the road traffic sector can not directly derived from the amount of emitted species, because they are also determined by local emissions of other anthropogenic and natural sources. In addition long range transport of precursors and ozone can play an important role in determining the local ozone budget. For a complete assessment of the impact of road traffic emissions it is therefore important to resolve both, local emissions and long range transport. This can be archived by the use of the newly developed MECO(n) model system, which on-line couples the global chemistry-climate-model EMAC with the regional chemistry-climate-model COSMO-CLM/MESSy. As both models use the same chemical speciation the boundary conditions are as consistent as possible. This allows a highly consistent model chain from the global to the local scale. To quantify the contribution of the road traffic emissions to the tropospheric ozone budget in Europe we use an accounting system of the relevant reaction pathways of the different species from different sources (called tagging method).This tagging scheme is implemented consistently on all scales, allowing a direct comparison of the contributions. With this model configuration we investigate the impact of road traffic emissions to the tropospheric ozone budget in Europe. For the year 2008 we compare different emission scenarios and investigate the influence of both model- and emission resolution. In addition results of a mitigation scenario for the year 2030 are presented, highlighting the importance of long range transport also for local mitigation strategies.