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Long-Range Correlations in Air Quality Time Series: Effect of Differencing and Shuffling

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Title Long-Range Correlations in Air Quality Time Series: Effect of Differencing and
Shuffling
 
Creator Lalwani, Asha
 
Subject Air Quality
Air Pollution
 
Description Long-range correlations in the air quality index (AQI) are analysed using rescaled range analysis (R/S), detrended
fluctuation analysis (DFA) and power spectral density analysis. Air quality index in five cities of India is considered for
this purpose. Statistical transformations such as differencing and shuffling have been carried out to examine the effect of
temporal correlations on long-range correlation property of the time series. All three methods indicated the presence of
persistence in original AQI time series. After differencing, long-range correlation property is, however, observed to be
distorted. R/S analysis did not show the similar results as DFA and power spectral density analysis. Shuffled time series is
shown to possess persistence as in the original one by using R/S analysis, whereas other two methods showed random
behaviour at most of the locations. This suggests that the persistence property is largely influenced by short-range
correlations in the AQI time series. The incorporation of this information can enhance the performance of the models to
forecast the air quality. The similarity in the results of DFA and power spectral density analysis suggests that both methods
can be relied more than R/S analysis in studying the persistence property of the time series.
 
Publisher Taiwan Association for Aerosol Research
 
Date 2016
 
Type Article
PeerReviewed
 
Format application/pdf
 
Identifier http://neeri.csircentral.net/901/1/22_AAQR-16-04-TN-0139_2302-2313.pdf
Lalwani, Asha (2016) Long-Range Correlations in Air Quality Time Series: Effect of Differencing and Shuffling. Aerosol and Air Quality Research, 16 (9). pp. 2302-2313. ISSN 1680-8584, ESSN: 2071-1409
 
Relation http://www.aaqr.org/
http://neeri.csircentral.net/901/