Irregularity analysis of CO, NO2 and O3 concentrations at traffic, commercial and low activity sites in Delhi

Abstract

The irregularity analysis of exceedance time series of gaseous pollutants CO, NO2 and O3 is carried out using Shannon entropy and Fisher information measure. The data observed during 2007–2010 at three sites with different land-use activities in Delhi are analyzed. CO and NO2 showed irregular behavior at both, low anthropogenic activity and commercial activity sites, whereas at traffic site both the pollutant concentrations showed regular behavior. The irregularity is attributed to the multiplicity in emission sources at low activity and commercial site and regular behavior is observed due to the uniformity and well defined source characteristics at the traffic site. O3 at three sites showed irregular behavior owing to its secondary nature. Fisher–Shannon information plane showed the grouping of three pollutants except CO and NO2 at traffic and O3 at low activity site suggesting the similar temporal characteristics of the pollutants even at the sites with different land-use activities.