O3 AND NOY RELATIONSHIPS AT A RURAL SITE

Measurements of O3, NO, NO2, peroxyacetyl nitrate (PAN), HNO3, 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 O3 and NO(y) at this rural site. A strong association was observed between the O3 and NO(x) oxidation product (NO(z) = NO(y) - NO(x)) levels. The higher O3 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 O3 production is about 10 molecules Of O3 produced for each molecule of NO(x) emitted. The analysis results also suggest that O3 net production continues until about 70% of the NO(x) has been converted into NO(z). The PAN/HNO3 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 O3 production.