Application of “closure” studies to marine aerosol
The presence of significant concentrations of organic material in marine aerosol has been appreciated for several decades; however, only recently has significant progress been made towards demonstrating that this organic content is biogenically formed. Marine organic compounds, presumed to be derived from phytoplankton exudates, show surface-active properties. The presence of organic surfactants in the marine aerosol composition might have a significant impact on the surface properties of the generated aerosols by affecting the particles' surface tension and solution balance properties, which might cause an effect on the subsequent cloud-nucleating processes. Nevertheless, the effect this material might have on the cloud-forming properties of aerosols remains entirely uncertain.Within the framework of the NERC-funded Characterisation of Organic Microlayer Produced Aerosols (COMPAS) project, modelling studies will be conducted in order to elucidate the influence of surface-active organic compounds present in the sea surface microlayer on the hygroscopicity and cloud-nucleating properties of marine aerosols. The ADDEM model will be used to predict the equilibrium composition of mixed inorganic/organic marine aerosol particles using input derived from measured surface tension and chemical functionality of biologically synthesised sea surface microlayer samples. The predictions of the model will be tested against experimental observations of the hygroscopic and cloud-nucleating behaviour of aerosols formed from different sea salt water and surface microlayer mixtures. This work will be carried out by Elena Fuentes-Lopez and Dave Topping.