The Evolution of Temporal and Spatial Patterns of Carbon Monoxide Concentrations in the Metropolitan Area of Sao Paulo, Brazil

Figure 3

Periodogram for SP6 station hourly average time series. The 7 peaks with highest spectral density represent the periods: 17.2 years, 12 hours, 1 year, 8.6 years, 5.7 years, 24 hours, and 7 days. The frequency unit is cycles per hour (CPH) and PSD is the power spectrum density.