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

Abstract

In this study, temporal variations of surface ozone (O3) were investigated at tropical urban site of Hyderabad during the year 2009. O3, oxides of nitrogen (NOx = NO + NO2), black carbon (BC), and meteorological parameters were continuously monitored at the established air monitoring station. Results revealed the production of surface O3 from NO2 through photochemical oxidation. Averaged datasets illustrated the variations in ground‐level concentrations of these air pollutants along different time scales. Maximum mean concentrations of O3 (56.75 ppbv) and NOx (8.9 ppbv) were observed in summer. Diurnal‐seasonal changes in surface O3 and NOx concentrations were explicated with complex atmospheric chemistry, boundary layer dynamics, and local meteorology. In addition, nocturnal chemistry of NOx played a decisive role in the formation of O3 during day time. Mean BC mass concentration in winter (10.92 µg m−3) was high during morning hours. Heterogeneous chemistry of BC on O3 destruction and NOx 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 O3 using multi‐linear regression method, which resulted in 91% of the overall variance.

Role of lightning phenomenon over surface O3 and NOx at a semi-arid tropical site Hyderabad, India: inter-comparison with satellite retrievals

“…Control day data is an average of 3 days before and after lightning day. The diurnal mean data of monthly mean showed a typical variation in NO x with morning and evening peak concentrations attributing to traffic emissions (Swamy et al 2012;Yerramsetti et al 2013b). Besides this, low wind speed and high relative humidity had contributed to localization of trace gases, resulting in higher concentration at peak hours.…”

“…In most of the events, the lightning intensity was high during post-noon to evening hours (14:00 to 20:00 h Indian Standard Time, IST), which might be due to surface heating by local convection (Sen Roy and Balling 2013). Although anthropogenic emissions are major sources of NO x at the monitoring site (Yerramsetti et al 2013b), significant variations in the concentrations of NO x and O 3 were observed during lightning events.…”

Significance of volatile organic compounds and oxides of nitrogen on surface ozone formation at semi-arid tropical urban site, Hyderabad, India

“…However, the destruction of O 3 has been observed with increasing NO x concentration, particularly in the urban lower tropospheric region (Yerramsetti et al 2013a). Relationship between NO x and VOCs on the formation of O 3 revealed that reduced VOCs/NO x ratios can enhance titration reaction of O 3 (Swamy et al 2012).…”

Validation of the SARAH-E Satellite-Based Surface Solar Radiation Estimates over India

“…On the other hand, rainfall scavenging during monsoon often lowers the overall aerosol loading of the atmosphere [23]. Anthropogenic industrial and automotive sources have a large impact on aerosol loading over the urban, densely industrialized sites such as Hyderabad or Bangalore [24,25]. Increased biomass burning during the cooler winter months leads to an increase in aerosol loading over several urban sites, such as Kolkata [26].…”