Prediction of source contributions to urban background PM<sub>10</sub> concentrations in European cities: a case study for an episode in December 2016 using EMEP/MSC-W rv4.15 – Part 2: The city contribution

Abstract. Despite the progress made in latest decades, air pollution is still primary environmental cause of premature death Europe. The urban population risks more likely to suffer related high concentrations pollutants, such as particulate matter smaller than 10 µm (PM10). Since composition these particulates varies with space and time, understanding origin essential determine most efficient control strategies. A source contribution calculation allows us provide information thus geographical location sources (e.g. city or country) responsible for episodes. In this study, calculations provided by regional European Monitoring Evaluation Programme/Meteorological Synthesizing Centre – West (EMEP/MSC-W) rv4.15 model a forecast mode, 0.25∘ longitude × 0.125∘ latitude resolution, based on scenario approach, have been explored. To do so, work has focused event occurring between 1 9 December 2016. This aims at quantifying over 34 cities, “city” PM10, i.e. from itself, an hourly basis. methodology used reduced anthropogenic emissions, compared reference run, choice percentage reductions tested using three different values (5 %, 15 50 %). definition contribution, area defining cities also important parameter. impact areas, studied was investigated (i.e. one grid cell, nine cells covering given global administrative GADM). Using % reduction emission larger our GADM) helps reduce non-linearity concentration changes. observed mismatch total sum calculated sources. When observed, it impacts NO3-, NH4+, H2O concentrations. However, mean represents only less 2 modelled PM10 system. During episode, found that 20 surface predicted had “city”, essentially composed components. total, 60 came countries domain, they were NO3- (by ∼ 35 two other secondary inorganic aerosols are components “rest Europe” since SO42- NH4+ represent together almost 30 contribution. rest mainly due natural It shown central impacted surrounding while located bit away Oslo Lisbon) contributions. usefulness forecasting tool illustrated example Paris, system able predict local polluted 1–2 2016, documented authorities.