Modelling the formation of organic particles in the atmosphere
O'Dowd, C. D.
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Anttila, T. Kerminen, V.-M.; Kulmala, M.; Laaksonen, A.; O'Dowd, C. D. (2004). Modelling the formation of organic particles in the atmosphere. Atmospheric Chemistry and Physics 4 , 1071-1083
Particle formation resulting from activation of inorganic stable clusters by a supersaturated organic vapour was investigated using a numerical model. The applied aerosol dynamic model included a detailed description of the activation process along with a treatment of the appropriate aerosol and gas-phase processes. The obtained results suggest that both gaseous sulphuric acid and organic vapours contribute to organic particle formation in continental background areas. The initial growth of freshly-nucleated clusters is driven mainly by condensation of gaseous sulphuric acid and by a lesser extent self-coagulation. After the clusters have reached sizes of around 2 nm in diameter, low-volatile organic vapours start to condense spontaneously into the clusters, thereby accelerating their growth to detectable sizes. A shortage of gaseous sulphuric acid or organic vapours limit, or suppress altogether, the particle formation, since freshly-nucleated clusters are rapidly coagulated away by pre-existing particles. The obtained modelling results were applied to explaining the observed seasonal cycle in the number of aerosol formation events in a continental forest site.