Ozone Formation Prediction by OH Reactivity Measurements

Abstract

We have developed a system that can measure OH reactivity by laser spectroscopy. Simultaneous measurements of the OH reactivity and reactive trace species were performed in various atmospheric environments. The OH reactivities derived from a chemical composition analysis were compared with direct measurements by the pump-probe laser method. As a result of observations at many places, such as areas with active anthropogenic activities (central area in Tokyo, Yokohama), suburban areas (Hachioji, Tsukuba, Kyoto), and forest (Manitou Colorado, Arida Wakayama, Tama hills), 120 kinds of VOCs and other reactive species were determined. However, 25–50% of an unknown reactivity was ubiquitously observed. In addition to ambient air observations to search for the origin of the unknown reactivity, analysis of the gas emitted from a single plant, exhaust gas analysis of gasoline cars by a chassis dynamometer, and analysis of air in which a photochemical reaction occurred in a smog chamber were conducted. As a result, the unknown reactivities could be responsible for the nonmeasured VOCs either of plant or anthropogenic origin and secondary VOCs generated in the atmosphere.