AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA
Abstract View
A Sensitivity Analysis of Organic Aerosol Retrieved Volatility Distributions to Kinetic Parameters
JAMES HITE, Kate Cerully, Athanasios Nenes, Georgia Institute of Technology
Abstract Number: 395 Working Group: Carbonaceous Aerosols in the Atmosphere
Abstract Atmospheric secondary organic aerosol (SOA) generated through the partitioning of semi-volatile organics into the condensed phase has both epidemiological and climatic impacts through the growth of particulate matter into relevant sizes for respiratory interactions and cloud condensation nuclei activity. SOA is often described in models by treating it as a mixture of components with differing partitioning coefficients through the volatility basis set (VBS) approach rather than explicitly resolving the complex chemistry (Donahue et al., Env. Sci. Tech., 40, 2635-2643, 2006).
A method of estimating the volatility parameters of monodisperse, single-component aerosol samples through measurements made with a thermodenuder built in-house and operated as part of a volatility tandem differential mobility setup has been developed and shown to produce results comparable to those in the literature (AS&T, in review). A similar approach is employed to interpret the volatilization rates of organic aerosol mixtures of dicarboxylic acids and ammonium sulfate with a kinetic model that resolves the gas to particle partitioning of aerosol, obtaining a condensed-phase volatility distribution using the VBS approach. An iterative optimization routine is utilized to obtain the partitioning coefficients, and different approaches to the volatility distribution retrieval are considered in the analysis. These experiments serve as a test for the optimization procedure as the mixtures are of known chemical composition – a necessary validation step prior to applying this technique to actual complex SOA mixtures.