Research Projects

This interim document reports on Phase II studies for a project involving "Statistical Oxidant/Precursor Relationships in the Los Angeles Basin." The purpose of Phase II is to collect, sort, and process all aerometric and meteorological data needed for the development of a model relating afternoon oxidant levels to morning precursor (HC and NO,) concentrations in the South Coast Air Basin (SCAB). In addition to collection and compilation of these data, this task involves a preliminary statistical analysis of these data as preparation for Phase III, creation of the empirical model. The principal goal of this preliminary analysis is to select the source and receptor sites and oxidant averaging periods most likely to be conducive to successful model development and to restrict the data base to days having appropriate wind flow to transport air from the chosen source sites to the receptors.

An important conclusion of this study is that an oxidant-precursor model for short-to-medium range transport (e.g., DOLA to Pasadena) will be easier to construct and probably more accurate than one for long-range transport. The major problem is that oxidant-precursor correlations tend to decrease with increasing source-to-receptor separation, becoming significantly negative at the largest transport distances. While this phenomenon seems reasonable physically and is therefore not necessarily indicative of low data quality or interference from unaccounted-for factors, it nonetheless may hinder the successful creation of an oxidantiprecursor model involving long-range transport.