The Influence of Biogenic Emissions Estimates on Ozone Precursor Control Requirements for Atlanta

Abstract

Over the past 15 years photochemical air quality simulation models have been used to simulate observed spatial and temporal patterns of ambient, ozone, and evaluate the merits of different emissions control approaches for reducing ozone. A coincident increase in our knowledge of atmospheric chemistry responsible for ozone formation has accompanied the use of source driven models which couple atmospheric transport processes with chemistry to provide concentration estimates. Most modeling applications for urban areas included only anthropogenic emissions sources and, typically, control of reactive organic gases (ROG) was shown to be an effective measure for reducing peak ozone. In contrast, the recent modeling work of Chameides et al. (1988) on the Atlanta area suggested that when natural emissions (principally isoprene and alpha-pinene) are included as sources, the effectiveness of anthropogenic ROG control is substantially reduced (relative to the case where natural emissions are not included). The Chameides work using the OZIPM4 (EPA, 1989) suggested that the level of anthropogenic ROG control needed to attain the ozone NAAQS (0.12 ppm) increased from roughly 30% to 70% when natural emissions were included for the modeling day, June 4, 1984. The OZIPM4 is a relatively simple trajectory model, however, and a natural question to be raised is whether similar results would be obtained with a more physically realistic model.