A model mechanism to describe oxidation of monoterpenes leading to secondary organic aerosol - 1. alpha-pinene and beta-pinene

A model mechanism to describe the oxidation of alpha-pinene and beta-pinene has been developed based on the chemistry of lower alkenes and smog chambe r studies of gas and aerosol phase products of monoterpene oxidation descri bed in the literature. The mechanism is designed to replace single-step aer osol yield or fractional aerosol coefficient approaches currently used in n umerical atmospheric chemistry transport models. The mechanism predicts the concentrations of condensable products which are partitioned between gas a nd aerosol phases based on the absorption approach of Odum et al. [1996] an d Hoffmann et al. [1997] but uses a six-product rather than a two-product m odel. Model-predicted aerosol concentrations and yields are similar to thos e observed in the smog chamber, and the timing of aerosol formation is in r easonable accord with that observed, The monoterpene mechanism is also used to develop aerosol "isopleths" based on NOx and alpha-pinene concentration s and temperatures representative of those found in the atmosphere.