Temporal and spatial variability of surface ozone at Delhi and Antarctica

Abstract

This study deals with the temporal and spatial variability of 365 days; hourly mean surface ozone data for three different locations, New Delhi (a site of intense anthropogenic activity), Syowa and McMurdo stations in Antarctica (sites of clean background air). The analysis not only shows the seasonal and diurnal variation of O3 over New Delhi and Antarctica, but also provides statistics of means and variability on a temporal scale. Eight-hour (9-17 h) surface O3 concentration at New Delhi (2001) was recorded, which was 59 of the WHO (80 ppb) ambient air quality standard for ozone. Likewise, the monthly mean of daily maximum O3 during April and November (2001) was observed, which was 97 of the WHO ambient air quality standard for ozone that indicates the serious ozone pollution in New Delhi. Mean rate of daytime photochemical production of surface O3 at Delhi (2001) has been observed around 7.1 ppb h-1 between 6 and 12 h, while, Syowa and McMurdo stations showed photochemical loss of surface O3 during daylight hours of about 1 ppb and 0.2 ppb, respectively. The diurnal trend observed during summer at Syowa station shows a sign of daytime photochemical depletion. The photochemical loss of surface O3 during summer months with respect to the winter maximum ozone was observed to be about 56 and 64 at Syowa and McMurdo stations, respectively. The day-to-day variability at Syowa and McMurdo station suggests that the major loss term is a process in the sea ice zone.