Abstract
In the present study, we have analyzed the spatial patterns of seasonal-scale diurnal cycle of three main pollutants, NO2, SO2, and O3, across five stations in Delhi. We used hourly data collected by the local pollution monitoring agencies for the time period, October 2010 to September 2013. Harmonic analysis was used to detect the diurnal cycle in the observed patterns of pollutants across Delhi. The results of our study indicated a consistently higher level of concentrations of all the pollutants at two of the stations, IGI Airport and Civil Lines, while lower concentration levels were observed in the mixed use residential areas of Shadipur and NSIT Dwarka. A clockwise gradual progression in the time of maximum from east to west was observed in the case of SO2 during each season. The time of maximum for O3 for each season was in the early evening hours, 1800 local standard time (LST). Moreover, there were little spatial variations in the peak time of occurrence of NO2 and O3 at the seasonal scale.
