Environmental monitoring of surface ozone and other trace gases over different time scales: chemistry, transport and modeling

Increasing concentration of tropospheric ozone (O3) is a serious air pollution problem faced commonly by the urban people. The present study emphasizes on variations of air pollutant concentrations viz., O3, nitrogen oxides (NOx), carbon monoxide (CO), sulfur dioxide (SO2) and black carbon (BC) at a tropical urban site located in the Deccan plateau region with semi-arid climate. The air monitoring site revealed typical diurnal/seasonal trends attributing to the complex chemistry of surface O3 formation from its precursors. Role of SO2 in the formation of free radical (HO2) and its impact on O3 concentration is distinguished part of the study. The results showed the highest mean O3 in summer (57.5 ± 15.2 ppbv) followed by winter and monsoon. Observations of BC aerosols showed the highest mean value during winter (8.2 ± 2 µg m-3) and the lowest in monsoon (4.2 ± 1 µg m-3). Besides local influences, long-range transport of air masses were also studied by simulating back trajectories at different elevations during the study period. Furthermore, statistical analysis and modeling was performed with both linear (regression) and nonlinear (neural network) methods.