Ozonolysis of α-pinene: parameterization of secondary organic aerosol mass fraction
Existing parameterizations tend to underpredict the alpha-pinene aerosol mass fraction (AMF) or yield by a factor of 2 & ndash;5 at low organic aerosol concentrations 5 mu g m(-3)). A wide range of smog chamber results obtained at various conditions (low/high NOx, presence/absence of UV radiation, dry/humid conditions, and temperatures ranging from 15-40 degrees C) collected by various research teams during the last decade are used to derive new parameterizations of the SOA formation from alpha-pinene are developed by fitting experimental data to a basis set of saturation concentrations (from 10(-2) to 10(4) mu g m(-3)) using an absorptive equilibrium partitioning model. Separate parameterizations for alpha-pinene SOA mass fractions are developed for: 1) Low NOx, dark, and dry conditions, 2) Low NOx, UV, and dry conditions, 3) Low NOx, dark, and high RH conditions, 4) High NOx, dark, and dry conditions, 5) High NOx, UV, and dry conditions. According to the proposed parameterizations the alpha-pinene SOA mass fractions in an atmosphere with 5 mu g m(-3) of organic aerosol range from 0.032 to 0.1 for reacted alpha-pinene concentrations in the 1 ppt to 5 ppb range.