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UP: Umweltphysik

UP 4: Atmosph
ärische Aerosole

UP 4.3: Fachvortrag

Monday, March 13, 2006, 17:00–17:15, E

Modeling Organic Films on Atmospheric Aerosol Particles and their Influence on Chemistry — •Linda Smoydzin and Roland von Glasow — Institut für Umweltphysik der Universität Heidelberg, Im Neuenheimer Feld 229, 69120 Heidelberg

It is well known that organic material from the ocean’s surface can be part of atmospheric aerosol particles often producing a surface film on the aerosol. Measurements have shown that an average organic mass fraction of 5-10% relative to the sea-salt content can be assumed. However it is an open question how strong the influence of organic matter on gas phase and sea salt chemistry in the marine atmosphere is. It is assumed that the most important influence of the organics is the reduced mass transfer between the gas and liquid phase due to a surface film. For studying the effect of organic surfactants on atmospheric chemistry we use a one-dimensional numerical model which contains a microphysics scheme and a detailed description of chemistry in the gas phase, in aerosol particles and in cloud droplets. A simple approach is used to simulate organic surface films on aerosol particles by using oleic acid as a proxy for organic compounds being present in the aerosol. If the concentration of oleic acid is large enough to form a monolayer on the particle the mass transfer between the gas and liquid phase is hindered. Lab measurements have shown that oleic acid can react with ozone which leads to a destruction of the organic film. By using this approach we want to find out in which way a reduced mass transfer between the gas and liquid phase might influence chemical processes in the marine atmosphere.