Global modeling of aerosol dynamics: model description, evaluation, and interactions between sulfate and nonsulfate aerosols

[1] The IMPACT global chemistry and transport model has been updated to include an aerosol dynamics module. Here it is used to simulate the dynamics of sulfate aerosol and its interaction with nonsulfate aerosol components: carbonaceous aerosol (organic matter (OM) and black carbon (BC)), dust, and sea salt. The sulfate aerosol dynamics is based on the method of modes and moments. In the current implementation, two modes are used for sulfate aerosol (nuclei and accumulation mode), and two moments are predicted within each mode (sulfate aerosol number and mass concentration). The aging of carbonaceous aerosol and dust particles from hydrophobic to hydrophilic depends on the surface coating of sulfate which occurs as a result of the condensation of sulfuric acid gas H2SO4 (g) on their surface, and coagulation with pure sulfate aerosol. The model predicts high sulfate aerosol number concentrations in the nuclei mode (over 104 cm3) in the tropical upper troposphere, while accumulation mode sulfate number concentrations are generally within 50–500 cm3 in most parts of the free troposphere. The model predicted mass concentrations of sulfate, OM, BC, dust, and sea salt, H2SO4 (g) concentration, aerosol number, and size distributions are compared with measuremen