Since the atmospheric variables are not expected to vary from one day of the week to another, the weekly cycling of the ozone signal provides an outstanding opportunity to study the man-induced ozone contribution. In particular, the weekly pattern analysis reveals the consequences of emission reductions from weekday to weekends. Hence, it represents an emission reduction scenario that can be verified by the available data. This report was prepared in support of the OTAG Air Quality Analysis Workgroup. The air quality analysis below, makes extensive use of the concepts of pattern and pattern analysis.
Pattern analysis is a structured approach to the organization and presentation of air quality data.
The ozone concentration at a given location is composed of contributions from global tropospheric background ozone , the regional ozone from the superimposed emissions within the OTAG region , and from urban ozone that is in excess of the tropospheric and regional background. The global-scale of tropospheric ozone constitutes the boundary condition for the regional ozone. Similarly, the regional ozone is the boundary condition of the urban ozone in a hierarchical relationship. Each scale exhibits a distinct temporal pattern. The seasonal scale is superimposed on the secular trend, the weekly cycle on the seasonal cycle, the diurnal cycle is superimposed on the weekly cycle, etc.