Evaluation of the size segregation of elemental carbon (EC) emission in Europe: influence on the simulation of EC long-range transportation

摘要

Elemental Carbon (EC) has a significant impact on human health and climatechange. In order to evaluate the size segregation of EC emission in theEUCAARI inventory and investigate its influence on the simulation of EClong-range transportation in Europe, we used the fully coupled onlineWeather Research and Forecasting/Chemistry model (WRF-Chem) at a resolutionof 2 km focusing on a region in Germany, in conjunction with ahigh-resolution EC emission inventory. The ground meteorology conditions,vertical structure and wind pattern were well reproduced by the model. Thesimulations of particle number and/or mass size distributions were evaluated withobservations at the central European background site Melpitz. The fine modeparticle concentration was reasonably well simulated, but the coarse modewas substantially overestimated by the model mainly due to the plume withhigh EC concentration in coarse mode emitted by a nearby point source. Thecomparisons between simulated EC and Multi-angle Absorption Photometers(MAAP) measurements at Melpitz, Leipzig-TROPOS and Bösel indicated thatthe coarse mode EC (ECc) emitted from the nearby point sources might beoverestimated by a factor of 2–10. The fraction of ECc was overestimated inthe emission inventory by about 10–30 % for Russia and 5–10 % forEastern Europe (e.g., Poland and Belarus). This incorrectsize-dependent EC emission results in a shorter atmospheric life time of ECparticles and inhibits the long-range transport of EC. A case study showedthat this effect caused an underestimation of 20–40 % in the EC massconcentration in Germany under eastern wind pattern.