Volume 8, No. 4, December 2008, Pages 381-391 PDF(271 KB)
Chaos in Air Pollutant Concentration (APC) Time Series
Chung-Kung Lee1, Shu-Chen Lin2
1 Green Environment R&D Center and Department of Environmental Engineering, Vanung University, Chungli, Taiwan, ROC
2 Department of Resources and Environment, Leader University, Tainan, Taiwan, ROC
Three chaotic indicators, namely the correlation dimension, the Lyapunov exponent, and the Kolmogorov entropy, are estimated for one-year long hourly average NO (nitrogen monoxide), CO (carbon monoxide), SO2 (sulfur dioxide), PM10 (particles with an aerodynamic diameter of approximately 10 μm or less), and NO2 (nitrogen dioxide) concentration to examine the possible chaotic characteristics in the air pollutant concentration (APC) time series. The presence of chaos in the examined APC time series is evident with the low correlation dimensions (3.42-4.71), the positive values of the largest Lyapunov exponent (0.128-0.427), and the positive Kolmogorov entropies (0.628-0.737). Since the existence of multifractal characteristics in the above time series has been confirmed in our previous investigations, the presence of chaotic behavior identified in the current study suggests the possibility of a chaotic multifractal approach for APC time series characterization. Some problems concerning the applicability of chaos analysis in air pollution are also discussed.
Air Pollutants; Multifractal.