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KMID : 1024520170260020221
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Journal of the Environmental Sciences
2017 Volume.26 No. 2 p.221 ~ p.230
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Analysis of the Long-term Trend of PM10 Using KZ Filter in Busan, Korea
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Do Woo-Gon
Jung Woo-Sik
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Abstract
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To determine the effect of air pollution reduction policies, the long-term trend of air pollutants should be analyzed. Kolmogorov-Zurbenko (KZ) filter is a low-pass filter, produced through repeated iterations of a moving average to separate each variable into its temporal components. The moving average for a KZ(m, p) filter is calculated by a filter with window length m and p iterations. The output of the first pass subsequently becomes the input for the next pass. Adjusting the window length and the number of iterations makes it possible to control the filtering of different scales of motion. To break down the daily mean PM10 into individual time components, we assume that the original time series comprises of a long-term trend, seasonal variation, and a short-term component. The short-term component is attributable to weather and short-term fluctuations in precursor emissions, while the seasonal component is a result of changes in the solar angle. The long-term trend results from changes in overall emissions, pollutant transport, climate, policy and/or economics. The long-term trend of the daily mean PM10 decreased sharply from 59.6 ug/m3 in 2002 to 44.6 ug/m3 in 2015. This suggests that there was a long-term downward trend since 2005. The difference between the unadjusted and meteorologically adjusted long-term PM10 is small. Therefore, we can conclude that PM10 is unaffected by the meteorological variables (total insolation, daily mean temperature, daily mean relative humidity, daily mean wind speed, and daily mean local atmospheric pressure) in Busan.
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KEYWORD
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PM10, KZ filter, Long-term trend
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