title: Quantitative Assessment of Parametric Uncertainty in Northern Hemisphere PAH Concentrations.
abstract: We quantitatively examine the relative importance of uncertainty in emissions and physicochemical properties (including reaction rate constants) to Northern Hemisphere (NH) and Arctic polycyclic aromatic hydrocarbon (PAH) concentrations, using a computationally efficient numerical uncertainty technique applied to the global-scale chemical transport model GEOS-Chem. Using polynomial chaos (PC) methods, we propagate uncertainties in physicochemical properties and emissions for the PAHs benzo[a]pyrene, pyrene and phenanthrene to simulated spatially resolved concentration uncertainties. We find that the leading contributors to parametric uncertainty in simulated concentrations are the black carbon-air partition coefficient and oxidation rate constant for benzo[a]pyrene, and the oxidation rate constants for phenanthrene and pyrene. NH geometric average concentrations are more sensitive to uncertainty in the atmospheric lifetime than to emissions rate. We use the PC expansions and measurement data to constrain parameter uncertainty distributions to observations. This narrows a priori parameter uncertainty distributions for phenanthrene and pyrene, and leads to higher values for OH oxidation rate constants and lower values for European PHE emission rates.
authors.affiliation: †Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.
authors.forename: Colin P
authors.initials: CP
authors.lastname: Thackray
authors.affiliation: ‡Department of Earth, Atmospheric and Planetary Science and Center for Global Change Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.
authors.forename: Carey L
authors.initials: CL
authors.lastname: Friedman
authors.affiliation: §School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02139, United States.
authors.forename: Yanxu
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: ∥Institute for Data, Systems and Society and Department of Earth, Atmospheric and Planetary Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.
authors.forename: Noelle E
authors.initials: NE
authors.lastname: Selin
mesh_terms: D001110:Arctic Regions; D001564:Benzo(a)pyrene / Q000032:analysis; D003198:Computer Simulation; D004785:Environmental Pollutants / Q000032:analysis*; D008956:Models, Chemical; D008962:Models, Theoretical; D010616:Phenanthrenes / Q000032:analysis; D011084:Polycyclic Aromatic Hydrocarbons / Q000032:analysis*; D011721:Pyrenes / Q000032:analysis; D035501:Uncertainty
chemical_list: D004785:Environmental Pollutants; D010616:Phenanthrenes; D011084:Polycyclic Aromatic Hydrocarbons; D011721:Pyrenes; D001564:Benzo(a)pyrene; C031181:phenanthrene; C030984:pyrene