SIMULATION OF FORMATION AND GROWTH OF ATMOSPHERIC SULFATE PARTICLES

This paper investigates the formation and growth of aerosol sulfate pa rticles in the atmosphere. The evolution of the aerosol size distribut ion with time was modeled using the aerosol general dynamic equation. This equation was solved numerically using a discrete-nodal point meth od to describe the particle size distribution. For the initial size di stribution we have used an average urban accumulation mode. The first step in our model considers the oxidation of SO2 by OH radicals, produ cing H2SO(g)(4). The next step considers the binary nucleation and con densation of the H2SO4-H2O system and its evolution due to coagulation and deposition mechanisms. A detailed description of the model is pre sented. The mass size distribution at different distances during the t ransport of the initial aerosol size distribution is also presented. T he importance of different mechanisms on the evolution of the aerosol size distribution is discussed. Sensitivity analysis was performed for many model parameters where simulations were made at varying temperat ure, relative humidity and photo-oxidation rate conditions. Model calc ulations suggest that condensation growth is the dominant mechanism fo r the evolution of the size distribution of sulfate particles during m oderate relative humidity conditions. Copyright (C) 1996 Elsevier Scie nce Ltd