Using Smog Chamber Data to Improve the Understanding of Soa Formation

The organic fraction of secondary particles, commonly known as secondary organic aerosols (SOA), constitutes a significant part of fine aerosols. The formation of SOA is subject to complicated coupling among gas-phase chemical reactions, aqueous -phase, aerosol-phase, and meteorological processes. To correctly predict total particle concentrations in the atmosphere it is necessary to understand the physical and chemical processes producing organic aerosols. Considering that the whole complexity of the processes and factors involved in SOA formation has not been completely understood, there is a need to isolate the chemical contribution in threedimensional photochemical models from other SOA formation origins. Measurements made under controlled environmental conditions, such as those performed in a smog chamber, offer a unique opportunity to study the chemical processes leading to SOA production. Therefore, the comparison with chamber data allows the evaluation of the chemical processes of SOA formation simulated by the chemical and aerosol modules used in CMAQ.