Dynamics of Air Pollutant Concentrations Time Series

• Main Authors: Yu-Yen Su, 蘇玉燕
• Other Authors: Yur-Tsai Lin
• Format: Others
• Language: zh-TW
• Published: 2000
• Online Access: http://ndltd.ncl.edu.tw/handle/31502051652739932388

碩士 === 元智大學 === 機械工程研究所 === 88 === One-year series of hourly average air pollutant concentration (APC) observations, including O3, CO, SO2 and NO2, were analyzed by means of statistical tools: histograms, time plot and multifractal analyses, to examine both the scale-invariant behavior and clustering characteristics of APC distribution in time. All APC distributions exhibit the characteristic unimodal and right-skewed shape. Time plot analysis reveals both the approximate stationary and long term memory in the time series. The APC time series were further investigated using a monodimensional fractal approach by calculating the box dimension. The results indicated that scale invariance indeed exists in APC time series and the box dimension was shown to be a decreasing function of the APC intensity level, whichsuggests multifractal characteristics, i.e. the weak and intense regions scale differently. To test this hypothesis, the APC time series were transferred into a useful compact form through the multifractal formalism, namely, the τ（q）-q and ｆ（α）-α plots. The analysis confirmed the existence of multifractal characteristics in the investigated APC time series. It was concluded that the origin of both the pronounced right-skewness and multifractal phenomena in APC distributions may be interpreted in terms of Ott proposed successive random dilution (SRD) theory and the dynamics of APC distribution process could be described as a random multiplicative process.