Role of Nitrogen Oxides, Black Carbon, and Meteorological Parameters on the Variation of Surface Ozone Levels at a Tropical Urban Site – Hyderabad, India

Abstract

Abstract In this study, temporal variations of surface ozone (O 3 ) were investigated at tropical urban site of Hyderabad during the year 2009. O 3 , oxides of nitrogen (NO x = NO + NO 2 ), black carbon (BC), and meteorological parameters were continuously monitored at the established air monitoring station. Results revealed the production of surface O 3 from NO 2 through photochemical oxidation. Averaged datasets illustrated the variations in ground‐level concentrations of these air pollutants along different time scales. Maximum mean concentrations of O 3 (56.75 ppbv) and NO x (8.9 ppbv) were observed in summer. Diurnal‐seasonal changes in surface O 3 and NO x concentrations were explicated with complex atmospheric chemistry, boundary layer dynamics, and local meteorology. In addition, nocturnal chemistry of NO x played a decisive role in the formation of O 3 during day time. Mean BC mass concentration in winter (10.92 µg m −3 ) was high during morning hours. Heterogeneous chemistry of BC on O 3 destruction and NO x formation was elucidated. Apart from these local observations, long‐range transport of trace gases and BC aerosols were evidenced from air mass back trajectories. Further, statistical modeling was performed to predict O 3 using multi‐linear regression method, which resulted in 91% of the overall variance.