TIME SCALES OF SURFACE OZONE VARIATIONS IN THE REGIONAL, NONURBAN ENVIRONMENT

A five-year (1985-1989) time series of the average diurnal maximum ozo ne concentration, O-3(t), was developed and examined in each of four 5 degrees latitude by 5 degrees longitude areas in the eastern United S tates. The time series was divided into four terms: the long-term mean , (O) over bar(3); the intra-annual perturbation, A(t'); the inter-ann ual perturbation, I(t''); and the synoptic perturbation, S(t). The sum of (O) over bar(3) and A(t') is the mean annual cycle for the daily m aximum ozone. In these four areas and in non-urban episode conditions, (O) over bar(3) and S(t) provided the major contribution to the obser ved daily maximum, accounting for about 70 to 85% of the ozone concent ration. However, there were individual instances at certain stations i n the four areas when the synoptic perturbation alone contributed as m uch as 60% to the observed ozone. A(t') accounted for up to 20% of the observed daily maximum in an episode situation, and I(t'') up to 13% in the ozone season. The results of this study suggest that control st rategies focused on reducing the magnitude of (O) over bar(3) and the annual range for A(t') can reduce the frequency of episodes in the ozo ne season, but because of large values of S(t) that have been observed , episodic control strategies will also be necessary to completely eli minate episodes. (C) 1997 Elsevier science Ltd.