Simulation of the effects of low-volatility organic compounds on aerosol number concentrations in Europe

Abstract. PMCAMx-UF, a three-dimensional chemical transport model focusing on the simulation of ultrafine particle size distribution and composition has been extended with addition reactions aging semivolatile anthropogenic organic vapors, emissions intermediate-volatility compounds (IVOCs), production extremely low-volatility (ELVOCs) by monoterpenes. The is applied in Europe to quantify effect these processes number concentrations. predictions are evaluated against both ground measurements collected during PEGASOS 2012 summer campaign across many stations airborne observations zeppelin measuring above Po Valley, Italy. PMCAMx-UF reproduces level daily average concentrations particles diameter larger than 100 nm (N100) normalized mean error (NME) 45 % bias (NMB) close 10 %. For same simulation, tends overestimate concentration (N10) NMB 23 NME 63 was able reproduce more 75 N10 N100 (zeppelin) within factor 2. According predictions, ELVOC monoterpenes leads surprisingly small changes over Europe. total decreased due formation 0.2 %, 1.1 N50 (particles 50 nm) increased 3 4 this new secondary aerosol (SOA) source. This change nonlinearity system, increases predicted some areas decreases others, but also cancelation effects various like accelerated growth coagulation. Locally, can be significant. example, an increase 20 %–50 Scandinavia significant (10 %–20 %) parts central ELVOCs contributed around 0.5 µg m?3 accounted for %–15 PM2.5 OA. IVOC their led surprising reduction (Ntot) 5 %–10 respectively, These were coagulation reduced nucleation rates.