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Ozone production efficiency and NO{sub x} depletion in an urban plume : interpretation of field observations and implications for evaluating O{sub 3}-NO{sub x}-VOC sensitivity.

Journal Article · · J. Geophys. Res.
Ozone production efficiency (OPE) can be defined as the number of ozone (O{sub 3}) molecules photochemically produced by a molecule of NO{sub x} (NO + NO{sub 2}) before it is lost from the NO{sub x} - O{sub 3} cycle. Here we consider observational and modeling techniques to evaluate various operational definitions of OPEs using aircraft and surface measurements taken as part of the 1999 Southern Oxidant Study field campaign in Nashville, Tennessee. A key tool in our analysis is a Lagrangian box model, which is used to quantitatively describe the effects of emissions, dilution, dry deposition, and photochemistry in an urban air parcel as it was advected downwind. After evaluating the model using the observed downwind concentrations of several key species, we show that the modeled NO{sub x} oxidation and O{sub 3} production rates as well as the associated instantaneous and cumulative OPEs depend on the time of day and the photochemical age of the air parcel. The observation-based OPEs are found to be consistent with the modeled values with the expected biases. A model sensitivity study suggests that downwind O{sub 3} concentrations in the Nashville plume are more sensitive to NO{sub x} emissions than anthropogenic VOC emissions. Because the OPE exhibits a nonlinear dependence on emissions and meteorological effects, it would be difficult to rely only on observations to map out the nonlinear response of O{sub 3} to a wide span of NO{sub x} and VOC emission changes. Properly constrained and well-evaluated models using a variety of observations are therefore necessary to reliably predict O{sub 3}-NO{sub x} -VOC sensitivity for designing effective O{sub 3} control strategies.
Research Organization:
Argonne National Laboratory (ANL)
Sponsoring Organization:
SC; EPA
DOE Contract Number:
AC02-06CH11357
OSTI ID:
961509
Report Number(s):
ANL/ER/JA-48542
Journal Information:
J. Geophys. Res., Journal Name: J. Geophys. Res. Journal Issue: D14 ; 2003 Vol. 108; ISSN JGREA2; ISSN 0148-0227
Country of Publication:
United States
Language:
ENGLISH