Characterization of Ambient Air Quality Data for Ozone and Its Precursors

Characterization of ozone episodes is extremely important. A key consideration in devising an effective control strategy is to ensure that the strategy works under a variety of conditions which have been observed to correspond with high measured ozone. The relative importance of ozone/precursors transported into an area is likely to be one important distinguishing characteristic of episodes. Thus, the needs to accurately characterize episodes and identify the potential role of transport are closely related. In a modeling analysis, performed to assess adequacy of proposed control strategies, it is important to have chosen a limited number of episodes which are representative of differing conditions leading to high observed ozone. More generally, a knowledge of meteorological, precursor characteristics and other ambient conditions which correspond with high ozone is useful in helping to formulate policies which are likely to lead to improvements in measured ozone levels. In this chapter, we present examples illustrating the added value of PAMS data in characterizing ozone episodes and identifying features that may be linked to significant pollutant transport.