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NOy by Chemiluminescence (ppt)

FIGURE 11.26 Measured NOv concentrations using catalytic converters and TP-LIF or chemiluminescence to measure the NO produced in the same flights as NO data in Fig. 11.24 (adapted from Crosley, 1996).

PPN (peroxypropionyl nitrate), methyl nitrate, n-propyl nitrate, and 2-butyl nitrate was, on average, 76 + 13% of the measured NOr

Figure 11.27 summarizes the ratio of the sum of the individual components of NO^ to the total NO^ measured using conversion to NO (Parrish et al., 1993). These data summarize measurements of NO, N02, PAN, HN03, and particulate nitrate as well as total NO^ at Whitetop Mountain (Tennessee), Bondville (Illinois), Scotia (Pennsylvania), and Egbert (Ontario, Canada). The median value (which is less influenced by extremes) of the percentage NOy that can be accounted for ranges from 75 to 94%, with all but the Bondville site being within experimental error of 100%.

TABLE 11.7 Measured Components of NOy at Niwot Ridge, Colorado, in Mid-1987"

Compound Percentage of NOr

NOv 32

PAN 24

" Adapted from Ridley et al. (1990a).

6 PPN = peroxypropionyl nitrate. ' NPN = «-propyl nitrate; 2BN = 2-butyl nitrate. '' MN = methyl nitrate.

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