Abstract:
Surface ozone levels are determined by the strengths of sources and precursor emissions, and by the meteorological conditions. Observed ozone concentrations are valuable indicators of possible health and environmental impacts. However, they are also used to monitor changes and trends in the sources of ozone and of its precursors, and for this purpose the influence of meteorological variables is a confounding factor. This report describes a study of ozone concentrations and meteorology in the Chicago area. The data are described using a variety of exploratory methods, including median polish and principal components analysis. The key relationships observed in these analyses are then used to construct a model relating ozone to meteorology. The model can be used to estimate that part of the trend in ozone levels that cannot be accounted for by trends in meteorology, and to "adjust" observed ozone concentrations for anomalous weather conditions. The model parameters are estimated by nonlinear least squares. Its goodness of fit is assessed by comparison with nonparametric regression results (lowess).
Keywords:
Ozone concentration. meteorological adjustment. nonlinear regression. nonparametric regression.
tr1.pdf