Ozone formation potential of organic compounds in the Eastern United States: a comparison of episodes, inventories, and domains.
Direct sensitivity analysis is applied for 3-D assessment of ozone reactivity (or ozone formation potential) in the Eastern United States. A detailed chemical mechanism (SAPRC-99) is implemented in a multiscale air quality model to calculate the reactivity of 32 explicit and 9 lumped compounds. Simulations are carried out for two different episodes and two different emission scenarios. While absolute reactivities of VOCs show a great deal of spatial variability, relative reactivities (normalized to the reactivity of a base mixture) produce a significantly more homogeneous field. Three types of domain-wide relative reactivity metrics are formed for 1-h and 8-h averaging intervals. In general, ozone reactivity metrics (with the exception of those based on daily peak ozone) are fairly robust and consistent between different episodes or emission scenarios. The 3-D metrics also show fairly similar rankings for VOC reactivity when compared to the box model scales. However, the 3-D metrics have a noticeably narrower range for species reactivities, as they result in lower reactivity for some of the more reactive, radical-producing VOCs (especially aldehydes). As expected, episodes and emission scenarios with less radical availability have higher absolute reactivities for all species and higher relative reactivities for the more radical-producing species. Finally, comparing the results with those from a different domain (central California) shows that relative reactivity metrics are comparable over these two significantly different domains.
Hakami
Amir
A
Department of Environmental Science and Engineering, California Institute of Technology, Pasadena, California 91125, USA.
Bergin
Michelle S
MS
Russell
Armistead G
AG
D000393:Air Pollutants / Q000032:analysis*; D005544:Forecasting; D008962:Models, Theoretical; D009930:Organic Chemicals; D010083:Oxidants, Photochemical / Q000032:analysis*; D010126:Ozone / Q000032:analysis*; D014481:United States
D000393:Air Pollutants; D009930:Organic Chemicals; D010083:Oxidants, Photochemical; D010126:Ozone