SPATIAL AND TEMPORAL VARIABILITY OF NONMETHANE HYDROCARBON MIXING RATIOS AND THEIR RELATION TO PHOTOCHEMICAL LIFETIME

The relationship between temporal and spatial variability of C-2-C-8 n onmethane hydrocarbon mixing ratios and their HO lifetimes (tau) is pr esented for samples collected during the 1993 North Atlantic Regional Experiment (NARE) and from other urban and remote sites. The C-2-C-4 a lkanes, acetylene and benzene typically define a trend of the form s(l nx) = A tau(-b) where slnx is the standard deviation of the In of the mixing ratio. The relationship extended over a wider range of hydrocar bons in winter. The exponent b ranged in value from 0.28 +/- 0.023 for winter urban data where C-2-C-8 hydrocarbons defined a strongly corre lated trend, to 0.56 +/- 0.15 for C2-C4 hydrocarbons at a coastal site in Nova Scotia during NARE. The trends are significantly different fr om that given by the Junge relationship [Junge, 1974]. Data from the A zores do not display such a trend and were likely influenced by local emissions. Variance trends are a useful analytical tool for examining the validity of hydrocarbon measurements.