Parameterization of secondary organic aerosol mass fractions from smog chamber data

A framework is presented and evaluated for the parameterization of smog chamber results for use in atmospheric chemical transport models (CTMs). The parameterization uses an absorptive partitioning model to describe formation of secondary organic aerosol (SOA). The key points of the framework are (1) the ability to fit results from several types of chamber experiments; (2) the use of a basis set of surrogate compounds characterized by fixed effective saturation concentrations instead of the more commonly used variable saturation concentrations; (3) calculation of uncertainties of the estimated SOA aerosol mass fractions (AMF) outside of the fitted experimental range; and (4) determination of the best effective enthalpy to reproduced observed temperature sensitivity. The features of this data analysis and fitting framework are demonstrated using simulated data, and actual measurements from α-pinene ozonolysis experiments. Representation of SOA formation using as many as 8 surrogate compounds with fixed effective saturation concentrations is shown to be feasible and has advantages over simpler parameterizations.