Organic material can make up a substantial fraction of ambient particulate matter, both in polluted urban areas and in cleaner rural and remote regions. Therefore they have the ability to impact the Earth radiative balance and human health at local, regional and global scales. Aerosols are made up of a complex mixture of inorganic and organic species with a wide range of functionalities and volatilities, making them one of the most challenging components of the atmosphere to characterize. Once organic compounds are emitted to the atmosphere they can undergo complex chemical and physical processes. The chemical processes involving aerosol species can also lead to changes in the physicochemical properties of ambient particles, such as their hygroscopicity, morphology and phase, diffusion of water and SVOCs, light scattering and absorption. Thus even with extensive study, our understanding of their sources, formation, evolution and vertical distribution in the atmosphere remains limited.

This session welcomes presentations that discuss the sources and evolution of organic aerosols in the atmosphere and how atmospheric processes transform ambient aerosols both in terms of their chemical composition and their physical properties.