O₃ and NO_<i>y</i> relationships at a rural site

Abstract

Measurements of O 3 , NO, NO 2 , peroxyacetyl nitrate (PAN), HNO 3 , and NO y were made during a 6‐week period in the summer of 1991 in Giles County, Tennessee. These data were analyzed to determine the factors controlling the relationship between O 3 and NO y at this rural site. A strong association was observed between the O 3 and NO x oxidation product (NO z = NO y ‐ NO x ) levels. The higher O 3 levels were associated with air masses impacted by higher NO x emissions that had been photochemically processed. An analysis of the data indicates that the ultimate O 3 production is about 10 molecules of O 3 produced for each molecule of NO x emitted. The analysis results also suggest that O 3 net production continues until about 70% of the NO x has been converted into NO z . The PAN/HNO 3 ratios observed suggest that the air masses in Giles County are composed of higher volatile organic carbon/NO x ratios than the air masses observed at other rural sites in eastern North America. A comparison of the data analysis results to model simulations and smog chamber experiments suggests that most of the time, Giles County is in an NO x ‐limited regime for O 3 production.