Ozone Formation Potential of Organic Compounds in the Eastern United States: A Comparison of Episodes, Inventories, and Domains
文摘
Direct sensitivity analysis is applied for 3-D assessmentof ozone reactivity (or ozone formation potential) in the EasternUnited States. A detailed chemical mechanism (SAPRC-99) is implemented in a multiscale air quality model to calculatethe reactivity of 32 explicit and 9 lumped compounds.Simulations are carried out for two different episodes andtwo different emission scenarios. While absolute reactivitiesof VOCs show a great deal of spatial variability, relativereactivities (normalized to the reactivity of a base mixture)produce a significantly more homogeneous field. Threetypes of domain-wide relative reactivity metrics are formedfor 1-h and 8-h averaging intervals. In general, ozonereactivity metrics (with the exception of those based ondaily peak ozone) are fairly robust and consistent betweendifferent episodes or emission scenarios. The 3-D metricsalso show fairly similar rankings for VOC reactivitywhen compared to the box model scales. However, the3-D metrics have a noticeably narrower range for speciesreactivities, as they result in lower reactivity for some ofthe more reactive, radical-producing VOCs (especiallyaldehydes). As expected, episodes and emission scenarioswith less radical availability have higher absolutereactivities for all species and higher relative reactivitiesfor the more radical-producing species. Finally, comparingthe results with those from a different domain (centralCalifornia) shows that relative reactivity metrics arecomparable over these two significantly different domains.