Atmos. Chem. Phys. Discuss., 11, 23421-23468, 2011
www.atmos-chem-phys-discuss.net/11/23421/2011/
doi:10.5194/acpd-11-23421-2011
© Author(s) 2011. This work is distributed
under the Creative Commons Attribution 3.0 License.
Review Status
This discussion paper has been under review for the journal Atmospheric Chemistry and Physics (ACP). Please refer to the corresponding final paper in ACP.
Parameterising secondary organic aerosol from α-pinene using a detailed oxidation and aerosol formation model
K. Ceulemans, S. Compernolle, and J.-F. Müller
Belgian Institute for Space Aeronomy (BIRA-IASB), Brussels, Belgium

Abstract. A new 10-product parameter model for α-pinene secondary organic aerosol (SOA) is presented, based on simulations with the detailed model BOREAM (Biogenic hydrocarbon Oxidation and Related Aerosol formation Model). The parameterisation takes into account the influence of temperature, type of oxidant, NOx-regime, photochemical ageing and water uptake, and is suitable for use in global chemistry transport models. BOREAM is validated against recent photooxidation smog chamber experiments, for which it reproduces SOA yields to within a factor of 2 in most cases. In the simple chemical mechanism of the parameter model, oxidation of α-pinene generates peroxy radicals, which, upon reaction with NO or HO2, yield products corresponding to high or low-NOx conditions, respectively. The model parameters – i.e. the temperature-dependent stoichiometric coefficients and partitioning coefficients of the 10 semi-volatile products – are obtained from simulations with BOREAM, including a prescribed diurnal cycle for the radiation, oxidant and emission levels, as well as a deposition sink for the particulate and gaseous products. The effects of photooxidative ageing are implicitly included in the parameterisation, since it is based on near-equilibrium SOA concentrations, obtained through simulations of a two-week period. Modelled SOA mass yields are about ten times higher in low-NOx than in high-NOx conditions, with yields of about 50 % in the low-NOx OH-initiated oxidation of α-pinene, considerably more than in previous parameterisations based on smog chamber experiments. The parameterisation is only moderately sensitive to the assumed oxidant levels. However, photolysis of species in the particulate phase is found to strongly reduce SOA yields. Water uptake is parameterised using fitted activity coefficients, resulting in a good agreement with the full model.

Citation: Ceulemans, K., Compernolle, S., and Müller, J.-F.: Parameterising secondary organic aerosol from α-pinene using a detailed oxidation and aerosol formation model, Atmos. Chem. Phys. Discuss., 11, 23421-23468, doi:10.5194/acpd-11-23421-2011, 2011.
 
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