Sources of organic aerosols in Central Europe identified with labelled species in a chemical transport model and a complementary measurement campaign.

This work is part of the project ‘TRACE’: Transport and transformation of atmospheric aerosol across Central Europe with emphasis on anthropogenic sources. Synergic measurement methods and state-of-the art modelling tools are combined to obtain a comprehensive picture of the contribution of transported anthropogenic aerosol compared to local emissions. Measurement data are available for three sites which are located in an important transition area between highly polluted and less polluted regions in Central Europe for winter 2021. This study focuses on the application of a simplified labelling approach within the COSMO-MUSCAT model (Wolke et al., 2012) for the identification of particulate matter sources. For this purpose, emissions of organic matter (OM) and black carbon were tracked by emission class and source country with a spatial resolution of about 2 km. The modelled source attribution shows a high contribution of residential heating to organic matter sources. While the model reproduces the OM values at two of our measuring stations quite well, the measured data are strongly underestimated at one station near Prague. Since we can reproduce the black carbon concentrations for this station reasonably well, we are confident that we are capturing the primary aerosols correctly. We assume an underestimation of anthropogenic volatile organic compound (AVOC) emissions from residential wood and coal burning, leading to an underestimation of secondary organic aerosols (SOA) produced by these precursors. Although biogenic sources account for the majority of VOCs, in urban environments light aromatic hydrocarbons emitted during combustion processes can contribute up to 30% of VOCs (Srivastava et al., 2022). Due to the low temperature dependence of these AVOCs, SOA formation occurs even in winter at lower temperatures (Bruns et al., 2016). This indicates that AVOC precursors could account for a considerable proportion of our SOA budget. So far, only the contribution of biogenic VOCs to SOA formation has been evaluated and improved in COSMO-MUSCAT. First results of the implementation of a new emission factor for anthropogenic VOCs from combustion sources and a corresponding SOA yield in COSMO-MUSCAT will be presented.   E. A. Bruns et al., “Identification of significant precursor gases of secondary organic aerosols from residential wood combustion,” Scientific Reports, vol. 6, no. 1, Jun. 2016, doi: DOI: 10.1038/srep27881. D. Srivastava, T. V. Vu, S. Tong, Z. Shi, and R. M. Harrison, “Formation of secondary organic aerosols from anthropogenic precursors in laboratory studies,” npj Climate and Atmospheric Science, vol. 5, no. 1, Mar. 2022, doi: https://doi.org/10.1038/s41612-022-00238-6. R. Wolke, W. Schröder, R. Schrödner, and E. Renner, “Influence of grid resolution and meteorological forcing on simulated European air quality: A sensitivity study with the modeling system COSMO–MUSCAT,” Atmospheric Environment, vol. 53, pp. 110–130, Jun. 2012, doi: doi:10.1016/j.atmosenv.2012.02.085.