Ozone process insights from field experiments - part II: Observation-based analysis for ozone production

A complete characterization of O-3 photochemistry from a regulatory point of view includes knowing the production rate for O-3, the sensitivity of this rate to NOx and VOCs, and the effects of emission controls on O-3 concentration. Observation-based analysis techniques have been developed to determine these quantities based on observed concentrations of O-3 and other photochemical ingredients. The promise of these methods is that reliable predictions on O-3 control measures will be forthcoming from easily made measurements. We review several techniques that have been used in recent field programs. Techniques are divided into two families according to whether predicted quantities pertain to the present state of an air parcel or to its history. The present time frame methods address the question of what is happening now, whereas the past time frame methods are used to determine how the air mass evolved to its present state. Present time frame methods are used to determine O-3 production rates and sensitivities. In this category, we discuss the constrained steady state, photostationary state, and radical budget methods. Past time frame techniques are used to address questions on the dependence of O-3 on precursor emissions. In this category, we discuss indicator species and the "observation-based model". (C) 2000 Elsevier Science Ltd. All rights reserved.