Bolchem: an On-Line Coupled Mesoscale Chemistry Model

Abstract. This work presents the on-line coupled meteorology-chemistry transport model BOLCHEM based on the hydrostatic meteorological BOLAM model, the gas chemistry module SAPRC90 and the aerosol dynamic module AERO3. It includes parameterizations to describe natural source emissions, dry and wet removal processes, as well as the transport and dispersion of air pollutants. The equations for different processes are solved on the same grid during the same integretation step, by means of operator splitting method. The paper describes the model and shows the model performances at continental scale for oneyear run (December 2009–November 2010). The results show that BOLCHEM reproduces both O₃ and PM₁₀ at surface. For O₃, we found the best agreement in the summer, with a correlation coefficient R of 0.7 and mean bias of 4.0. On the contrary, PM10 is better reproduced in the winter, with a correlation coefficient R of 0.6 and the mean bias MB of 6.7.