Atmospheric aerosols may participate in multiple particle-cloud droplet interconversion cycles during their atmospheric lifetime. Particles nucleate cloud droplets or get scavenged by already existing droplets, partially or completely dissolve, undergo aqueous chemical and photochemical processes, and finally evaporate leaving cloud-processed particles behind. Each such cycle may significantly and irreversibly change the chemical composition and have dramatic effects on the optical and hygroscopic properties of the particles. This talk will discuss the extent and mechanism of formation of light-absorbing compounds during storage, evaporation, and UV irradiation of aqueous solutions of secondary organic aerosols studied with high-resolution mass spectrometry and UVVIS spectroscopy. We will discuss the conditions under which cloud processing can serve as a mechanism for generation of atmospheric �brown carbon� aerosols.

Effect of chemical and photochemical cloud processing on the light absorption properties of biogenic secondary organic aerosols

242nd National Meeting (2011)

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