Seminar

Abstract

Organic aerosol (OA) comprises a large fraction of the global aerosol burden. The majority of OA is secondary, i.e. formed from precursor gases in the atmosphere. Traditionally, secondary organic aerosol (SOA) is assumed to be formed by absorption of low-volatility or semivolatile compounds into pre-existing aerosol particles. In addition to these pathways, many laboratory, field and model studies point to unique chemical reactions in cloud/fog droplets and wet aerosols that also lead to SOA products (aqSOA). I will discuss the underlying mechanisms of aqSOA formation. Some examples will be shown of the application of process models that could explain the formation of ambient aqSOA tracers. In addition, it will be shown how the description of aqSOA formation can be simplified to be implemented in larger scale models. The aqueous phases of cloud/fog droplets and wet aerosol particles, respectively, greatly differ in their water content and ionic strength. These properties will be contrasted and consequences for aqSOA formation in both aqueous media will be discussed.

Finally, an outlook will be given how to complete our view and understanding of the cloud chemistry and physics in general and specifically for aqSOA formation.

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Barbara Ervens is Research Scientist III at the NOAA Chemical Sciences Division, working in the Clouds and Aerosol Program. She earned a PhD in Chemistry from the University of Leipzig (Germany). Barbara began to work at NOAA in 2002, where her research focuses on the development and application of process models describing cloud chemistry, SOA formation and ice microphysics.