Development and preliminary validation of a modal aerosol model for tropospheric chemistry: MAM

This paper presents a modal aerosol model (MAM) developed to be used in three dimensional air quality models. MAM, which represents the aerosol distribution with four modes, has the advantage of simplicity and speed efficiency associated to modal models, while mass transfer is modeled with a dynamic approach. To assess the ability of MAM to represent mass transfer, MAM is compared to a size-resolved model based on the dynamic approach and to a version of MAM based on an equilibrium approach. Comparisons are done using measurements of inorganic species made in Japan as initial conditions. Furthermore, it is shown that MAM combined with a well chosen mode splitting scheme is able to deal accurately with the simultaneous occurrence of strong nucleation/condensation and coagulation, as may be observed in high nucleation episodes.