1Division of Nuclear Physics, Department of Physics, Lund University, Lund, Sweden
2TNO Netherlands Organisation for Applied Scientific Research, Utrecht, the Netherlands
3EMEP MSC-W, Norwegian Meteorological Institute, Oslo, Norway
4Dept. Earth & Space Sciences, Chalmers Univ. Technology, Gothenburg, Sweden
5Department of Applied Environmental Science (ITM), Stockholm University, Sweden
6National Centre for Atmospheric Science, Division of Environmental Health & Risk Management, School of Geography, Earth & Environmental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
7School of Physics & Centre for Climate and Air Pollution Studies, Ryan Institute, National University of Ireland Galway, Galway, Ireland
8NILU, Norwegian Institute for Air Research, Kjeller, Norway
9Department of Environmental Sciences/Center of Excellence in Environmental Studies, King Abdulaziz University, P.O. Box 80203, Jeddah, 21589, Saudi Arabia
10Finnish Meteorological Institute, Air Quality, P.O. Box 503, 00101 Helsinki, Finland
11Leibniz-Institut für Troposphärenforschung (TROPOS), Permoserstraße 15, 04318 Leipzig, Germany
12Department of Chemistry and Microbiology, University of Gothenburg, 412 96 Gothenburg, Sweden
13Swedish Meteorological and Hydrological Institute, 601 76 Norrköping, Sweden
Abstract. The atmospheric concentration of elemental carbon (EC) in Europe during the six-year period 2005–2010 has been simulated with the EMEP MSC-W model. The model bias compared to EC measurements is less than 20% for most of the examined sites. The model results suggest that fossil fuel combustion is the dominant source of EC in most of Europe but there are important contributions also from residential wood burning during the cold seasons and, during certain episodes, also from open biomass burning (wildfires and agricultural fires). The modelled contributions from open biomass fires to ground level concentrations of EC is small at the sites included in the present study, < 3% of the long-term average of EC in PM10. The modelling of this EC-source is subject to many uncertainties and for some episodes it is likely underestimated.
EC measurements and modelled EC were also compared to optical measurements of black carbon (BC). The relationships between EC and BC (as given by mass absorption cross section, MAC values) differed widely between the sites, and the correlation between observed EC and BC is sometimes poor, making it difficult to compare results using the two techniques and limiting the comparability of BC measurements to model EC results.
A new bottom-up emission inventory for carbonaceous aerosol from residential wood combustion has been applied. For some countries the new inventory has substantially different EC emissions compared to earlier estimates. For Northern Europe the most significant changes are much lower emissions in Norway and higher emissions in neighbouring Sweden and Finland. For Norway and Sweden, comparison to source-apportionment data from winter campaigns indicate that the new inventory may improve model calculated EC from wood burning.
Finally, three different model setups were tested with variable atmospheric lifetimes of EC in order to evaluate the model sensitivity to the assumptions regarding hygroscopicity and atmospheric ageing of EC. The standard ageing scheme leads to a rapid transformation of the emitted hydrophobic EC to hygroscopic particles and generates similar results as assuming that all EC is aged at the point of emission. Assuming hydrophobic emissions and no ageing leads to higher EC concentrations. For the more remote sites, the observed EC concentration was in between the modelled EC using standard ageing and the scenario treating EC as hydrophobic. This could indicate too rapid EC ageing in the model in relatively clean parts of the atmosphere.