THE CORRELATION OF TEMPERATURE AND RURAL OZONE LEVELS IN SOUTHEASTERNUSA

As a part of the southern oxidant study, a comprehensive air quality s tudy was performed at a rural site in southern Tennessee. The observat ions performed between 25 July and 2 September 1991 included measureme nts of primary and secondary pollutants as well as meteorological meas urements. Relatively high levels of NOy were observed when CO and SO2 levels were at estimated regional background indicating a significant non-combustion source. A multivariate linear regression analysis sugge sted that nearly 2/3 of the NOy above the estimated regional backgroun d level relates to SO2 emitting sources with the remaining 1/3 to CO e mitting sources. The association between primary pollutants and temper ature was found to be weak or insignificant. However, most secondary p ollutants (except PAN) positively correlated with temperature. In the case of O-3, a better association was found with a combination of temp erature and NOy. Comparison between the observation and model simulati on suggested that approximately 50% of the increase in O-3 levels obse rved at the Giles site may relate to the intrinsic dependence of rate constants on temperature. The number of O-3 molecules produced per NOy molecule present increases with temperature (between 22 and 33 degree s C) as did the chemical air mass age (NOx/NOy). On the other hand, th e number of O-3 molecules produced per molecule of NOx consumed remain ed nearly constant. The difference between NOz and the sum of the indi vidual NOz species measured separately (PAN, HNO3 and nitrate aerosol) suggests the presence of an additional NOz species that increased wit h temperature. (C) Published by Elsevier Science Ltd.