An examination of the local meteorology and chemical processes that lead to the simultaneous rise of ozone and fall of NOx in the morning.

Abstract

A better understanding of exactly what causes measured O3 mixing ratio increases in the mid-morning to early afternoon time period over rural northern Michigan was sought by this study. Four separate instances of increased O3 mixing ratios were examined in detail looking at a wide variety of meteorological and chemical variables. An attempt was made in all of these cases to determine the extent to which the mixing ratio increase could have been caused by photochemical production, boundary layer entrainment and/or horizontal advection. Examples of all three phenomenon were encountered. Meteorological parameters at the Program for Research on Oxidants, PHotochemistry, Emissions, and Transport (PROPHET) tower were compared with meteorological parameters at the UV-B site and were found to be similar. Mixed layer height determination made at the UV-B site were thus considered to be useful to examine O3 and NOx data collected at the PROPHET tower.