Establishing the Origin of Particulate Matter in Eastern Germany Using an Improved Regional Modelling Framework

In Eastern Germany winter episodes with PM10 exceedances of EU limit values are often connected to continental air masses, combining polluted air from Eastern Europe with air pollution from local urban sources. The EU air quality legislation requires the analysis of the contribution of such cross-boundary transport to exceedances for development of effective policy measures. To this end we have performed a source apportionment study to establish the main sources of particulate matter during high PM episodes in Eastern Germany. We have run the LOTOS-EUROS model with its labelling based source apportionment tool and found that the contribution from cross boundary transport becomes more dominant during the episodes. The results from the model are currently compared to a measurement based source attribution (PMF) and a more detailed evaluation of episodes with exceedances is being performed. The modelled concentrations have been evaluated against PM composition observations which revealed that especially the modelling of carbonaceous aerosol is challenging and lead to a large underestimation of modelled PM10 levels in winter. The use of an updated bottom-up inventory in combination with temperature dependent temporal variability for residential combustion emissions leads to an increase of carbonaceous aerosols and reduction of PM biases. Another improvement was realised through an update of the deposition routine over snow that leads to a strong reduction of the underestimation during cold PM episodes with snow conditions. © Springer Nature Switzerland AG 2020.