Spatial and Temporal Analysis of Non-Urban Ozone Concentrations over the EasternUnited States Using Rotated Principal Component Analysis

摘要

The spatial and temporal variability of O3 concentrations over the eastern UnitedStates during the period 1985 through 1990 was examined through the use of a multivariate statistical technique called Principal Component Analysis. The original data set, which contained 77 correlated variables (monitors) was reduced to six uncorrelated principal components, while still explaining almost two-thirds (64.02) of the total variance. Application of Kaiser's Varimax rotation led to the identification of six separate, contiguous subregions which each exhibit statistically unique O3 concentration characteristics. The results have provided a statistically and physically based rationale for choosing distinctive geographical areas for interpreting O3 air quality distributions and trends. Since data from stations within subregions exhibit homogeneous variability, the authors have been able to develop regionwide O3 indicators which have provided meaningful insight into the seasonal and annual concentration trends of the six subregions. The analysis has also suggested that trends analyses for determining general progress in improving O3 air quality could be based on aggregate statistics from clusters of monitors rather than from individual stations.