In the atmosphere, water usually requires an exisiting surface to make the transition from vapor to a liquid phase. The exact role of organic components in controlling how cloud condensation nuclei evolve and how cloud droplet activation takes place presently remains uncertain, but potentially has implications for both weather and climate issues. In a continuation of a previous award (ATM-0336296), Carnegie Mellon investigators will seek further integration of laboratory based investigations, chemical transport modeling and selected ambient atmospheric observation of the hygroscopic behaviour of representative aerosols types. Key interpretive properties are particle composition, solubility, hygroscopic growth and ageing effects, volatility of secondary organic aerosol components and the ability of ambient particulates to act as cloud condensation nuclei. A suite of aerosol characterization and compositional measurements tasks will be used to further these investigations.
