Chemically and size-resolved aerosol mass size distributions are simulated online using the Intermediate Model of Global Evolution of Species (IMAGES). Aerosol-phase thermodynamics is coupled to this chemical transport model using the Simulating Composition of Atmospheric Particles at Equilibrium (SCAPE2) module. Emphasis is placed on the equilibrium concentrations of aerosol ammonium, nitrate, sulfate, and water content subject to the interaction with ions from sea salt and dust. Transport for both aerosol and gas-phase species is solved using a semi-Lagrangian scheme driven by monthly mean climatological variables provided by European Centre for Medium-Range Weather Forecasts (ECMWF) analysis. This study presents estimates of annual average dry mass size distributions at selected stations in North America and Europe. Simulations are performed to observe the major differences between the coupled IMAGES-SCAPE2 model and IMAGES alone for key aerosol species. Nitrate concentrations predicted with IMAGES-SCAPE2 compare better with observations than those calculated with IMAGES alone. Model results show that aerosol size distributions are generally bimodal. This study finds that over polluted continental regions, the presence of sea-salt and dust aerosol potentially increases the formation of sulfate by 20--80%. Nitrate formation is enhanced by 14--60%, whereas ammonium formation is decreased by 20--60%. Nitrate plays an important role to determine the size distributions in many European stations. The presence of water changes the general shape of the size distribution, placing maximum values on larger size ranges.