TY - JOUR
T1 - Modeling organic aerosol from the oxidation of α-pinene in a Potential Aerosol Mass (PAM) chamber
AU - Chen, S.
AU - Brune, W. H.
AU - Lambe, A. T.
AU - Davidovits, P.
AU - Onasch, T. B.
N1 - Copyright:
Copyright 2014 Elsevier B.V., All rights reserved.
PY - 2013/5/15
Y1 - 2013/5/15
N2 - A model has been developed to simulate the formation and evolution of secondary organic aerosol (SOA) and was tested against data produced in a Potential Aerosol Mass (PAM) flow reactor and a large environmental chamber. The model framework is based on the two-dimensional volatility basis set approach (2D-VBS), in which SOA oxidation products in the model are distributed on the 2-D space of effective saturation concentration (Ci *) and oxygen-to-carbon ratio (O: C). The modeled organic aerosol mass concentrations (COA) and O: C agree with laboratory measurements within estimated uncertainties. However, while both measured and modeled O: C increase with increasing OH exposure as expected, the increase of modeled O: C is rapid at low OH exposure and then slows as OH exposure increases while the increase of measured O: C is initially slow and then accelerates as OH exposure increases. A global sensitivity analysis indicates that modeled COA values are most sensitive to the assumed values for the number of Ci* bins, the heterogeneous OH reaction rate coefficient, and the yield of first-generation products. Modeled SOA O: C values are most sensitive to the assumed O: C of first-generation oxidation products, the number of Ci* bins, the heterogeneous OH reaction rate coefficient, and the number of O: C bins. All these sensitivities vary as a function of OH exposure. The sensitivity analysis indicates that the 2D-VBS model framework may require modifications to resolve discrepancies between modeled and measured O:C as a function of OH exposure.
AB - A model has been developed to simulate the formation and evolution of secondary organic aerosol (SOA) and was tested against data produced in a Potential Aerosol Mass (PAM) flow reactor and a large environmental chamber. The model framework is based on the two-dimensional volatility basis set approach (2D-VBS), in which SOA oxidation products in the model are distributed on the 2-D space of effective saturation concentration (Ci *) and oxygen-to-carbon ratio (O: C). The modeled organic aerosol mass concentrations (COA) and O: C agree with laboratory measurements within estimated uncertainties. However, while both measured and modeled O: C increase with increasing OH exposure as expected, the increase of modeled O: C is rapid at low OH exposure and then slows as OH exposure increases while the increase of measured O: C is initially slow and then accelerates as OH exposure increases. A global sensitivity analysis indicates that modeled COA values are most sensitive to the assumed values for the number of Ci* bins, the heterogeneous OH reaction rate coefficient, and the yield of first-generation products. Modeled SOA O: C values are most sensitive to the assumed O: C of first-generation oxidation products, the number of Ci* bins, the heterogeneous OH reaction rate coefficient, and the number of O: C bins. All these sensitivities vary as a function of OH exposure. The sensitivity analysis indicates that the 2D-VBS model framework may require modifications to resolve discrepancies between modeled and measured O:C as a function of OH exposure.
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U2 - 10.5194/acp-13-5017-2013
DO - 10.5194/acp-13-5017-2013
M3 - Article
AN - SCOPUS:84896693418
VL - 13
SP - 5017
EP - 5031
JO - Atmospheric Chemistry and Physics
JF - Atmospheric Chemistry and Physics
SN - 1680-7316
IS - 9
ER -