Correlation of secondary organic aerosol with odd oxygen in

> 0.9. The dependence of the observed proportionality onthe gas-phase hydrocarbon profile is discussed. Theobservationally-based correlation between oxygenatedorganic aerosol mass and odd oxygen may provide insightinto poorly understood secondary organic aerosolproduction mechanisms by leveraging knowledge of gas-phase ozone production chemistry. These results suggestthat global and regional models may be able to use theobserved proportionality to estimate SOA as a co-product ofmodeled O