Nonlinear Response of Ozone to Emissions: Source Apportionment and Sensitivity Analysis

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• 作者：Daniel S. Cohan ; Amir Hakami ; Yongtao Hu ; and Armistead G. Russell
• 刊名：Environmental Science & Technology
• 出版年：2005
• 出版时间：September 1, 2005
• 年：2005
• 卷：39
• 期：17
• 页码：6739 - 6748
• 全文大小：507K
• 年卷期：v.39,no.17(September 1, 2005)
• ISSN：1520-5851

文摘

For secondary air pollutants, precursor emissions mayimpact concentrations in nonlinear and interdependentmanners. We explore the nonlinear responses of one suchpollutant, ozone, to emissions of its precursors, nitrogenoxides (NO_x) and volatile organic compounds. Modeling isconducted for a high ozone episode in the southeasternUnited States, applying a second-order direct sensitivitymethod in a regional air quality model. As applied here, thesensitivity method neglects most aerosol and aqueouschemistry processes. Inclusion of second-order sensitivitiesis shown to enable accurate characterization of responseto large perturbations in emissions. An index is introducedto characterize the nonlinearity of ozone response to NO_xemitted from each source region. Nonlinearity is foundto increase with the tonnage and emission density of thesource region. Interactions among the impacts of emissionsources are shown to lead to discrepancies between sourcecontribution attributed to an ensemble of emitters andthe sum of the contributions attributed to each component.A method is introduced for applying these "cross-sensitivity" interactions to assess the uncertainty ofsensitivity and source apportionment estimates arisingfrom uncertainty in an emissions inventory. For ozone responseto NO_x, underestimates in emission rates lead to underprediction of total source contribution but overprediction ofper-ton sensitivity.