In the Transport Analyses section of Volume II: Summary and Integration of Results, a paragraph is devoted to the power plant plume measurements around Nashville during the summer of 1995. There is a statement in this paragraph that could be interpreted to be far more general than it should be in light of what is in the peer-reviewed literature. The potential confusion arises from the wording, "during the daytime in the southern summer boundary layer, essentially all of the NOx is converted to NOz within 30 - 100 km of the source. Thus, ozone production due to NOx in the plume ceases within 100 km of the power plant." I believe this is based on the Cumberland power plant plume. This result, however, is specific to the meteorological conditions at the time the measurements were taken, i.e., very stagnant wind conditions during the summer of 1995. To give a more general picture, I think another measurement of the Cumberland plume should also be acknowledged. An article by Gillani and Pleim, Atmos. Envt., Vol. 30 pp. 2043-2059 (1996) presents results from measurements of the Cumberland plume obtained by aircraft on 23 Aug 1978 (Fig. 11, p. 2057). What's of interest is that on this particular day, ozone levels within the center of the Cumberland plume were about 70 ppb at 110 km downwind of the stack (NOx appeared to be depleting ozone), whereas ozone reached about 120 ppb in the plume center at 160 km downwind of the stack. This strongly suggests that NOx photochemistry was still occurring on this particular day in the plume at distances greater than 110 km. It also suggests that significant ozone transport would occur beyond 160 km downwind from the power plant. Conceivably, ozone production could still have been going on at 160 km, but that is speculative. A more general conclusion would be that ozone production from NOx in power plant plumes may be complete at distances of less than 100 km under some meteorological conditions (e.g., stagnant winds), but can extend beyond 100 km under other meteorological conditions. This is a more general conclusion that takes into account both the SOS 1995 measurements and the earlier measurements of 1978 for the Cumberland power plant.
Describe and illustrate current nonattainment problem and role of transport. Discuss CASAC recommendations for an 8-hour standard and EPA’s proposal for a new standard.
Briefly summarize pre-OTAG analyses of transport in the eastern U.S.
