Multicomponent aerosol dynamics model with gas/particle transport and modal approach

A multicomponent aerosol dynamic model, that is suitable for regional/global chemical transport models, was developed by combining a thermodynamic module and a modal approach module and by using a dynamic gas/aerosol relationship. The modal approach, which represents the particle size distribution as the superposition of three log-normal size distributions without any assumption on the characteristics of the log-normal distribution, was introduced for simulating the evolution of the chemical species of aerosol particles efficiently. The dynamic approach was utilized for gas/particle transport mechanisms to simulate mass transfer between the gas phase and size-resolved aerosol particles. Both dynamic approaches-the local equilibrium method and global equilibrium method-are compared, and the importance of dynamic approach compared to the equilibrium approach is demonstrated. It is also shown that the global equilibrium method can reduce the computing time significantly compared to the conventional local equilibrium method without much loss of accuracy.