Toward a New Chemical Mechanism in WRF/Chem for Direct and Indirect Aerosol Effects: A Focus on the Carbonaceous Aerosols Air Pollution Modeling and its Application XXII
An updated version of Weather Research and Forecasting/Chemistry model (WRF/Chem) with a new parameterization for the secondary organic aerosol (SOA) production based on the Volatility Basis Set (VBS) is evaluated over Europe in May–June 2003. Results are compared against surface observations issued from the EC/OC 2002–2003 campaign of European Monitoring and Evaluation Program (EMEP). WRF/Chem underestimates the elemental carbon (EC) and the organic aerosol mass (OA) by −7 and −38 %, respectively. The analysis of OA: EC ratio reveals that the under prediction may be mainly explained by a misrepresentation of anthropogenic emissions of carbonaceous aerosols due to the coarse resolution of the inventory. The modeled concentration of OA constituent is nearly constant during the day. The predicted SOA/OA ratio has a value of ∼80 %. The biogenic SOA (BSOA) are 30 % of the total OA mass. Dry deposition velocity of Volatile Organic Compounds (VOC) oxidation products is a source of uncertain in the SOA budget.