Previous studies have examined the correlations between ozone and its precursors using either measurements taken under episodic conditions or modeling results from historical episodes (Trainer et.al, 1993 ) and (Mathur, et.al, 1994). Also the concept of indicator species has been developed to determine different chemical regimes, namely, VOC -limited and NOx -limited conditions (Sillman et.al, 1995). It is well known that time series of ozone contain different time scales, refelecting different physical and chemical processes (Rao et.al, 1997).
Recognizing this, photochemical models are now being applied to the entire summer season as opposed to few episodic conditions. In this paper, we examine the space/time scales in the precursor concentrations and the temporal behavior of indicator species over the eastern United States as predicted by the UAM-V model for the 1995 summer season. The modeling simulations also include several hypothetical emission reductions scenarios. The seasonal ozone modeling results enable us to assess the relationship between ozone and its precursors on different scales, reflecting intra-day variations, diurnal variations, synoptic-scale variations, and longer- term variations. To this end the modeling domain is divided into urban regions in the Northeast (New York Metropolitan area, Baltimore -Washington area) and in the Midwest (Lake Michigan area), a semiurban region (Central Pennsylvania), and a rural region (Giles county in Tennessee). The spatial and temporal variability in the relationship between ozone and its precursors (NOx, NOy and VOC) as predicted by the UAM- V model for the base case and emissions reduction scenarios is discussed in this paper.
References
Trainer, M. , et al. 1993: Correlation of ozone with Noy in photochemically aged air, J Geophys. Res., 93, 2917- 2925.
Mathur, R. ,et al. 1994: Dependencies and sensitivity of tropospheric oxidants to precursor concentrations over the Northeast United States: A model Stydy, J Geophys Res. , 99, 10,535- 10,552.
Rao, S. T., Zurbenko, I.G. , et al. 1997: Space and time scales in ambient ozone data, Bulletin of American Meteorological Society, 78, 2153 -2166.
Sillman, Sanford, 1995: The use of NOy, H2O2, and HNO# as indicators for ozone -NOx - hydrocarbon sensitivity in urban location, J Geophys Res., 100, 14, 175 -14, 188.
Symposium on Interdisciplinary Issues in Atmospheric Chemistry