Statistical analysis of tropospheric ozone and its precursors using principal component analysis in an urban area of Surat, India

Abstract

The objective of this study was to investigate the sources of tropospheric ozone (O3) precursors in an urban area using principal component analysis. Chemically reactive conventional pollutants such as carbon monoxide (CO), carbon dioxide (CO2), nitric oxide (NO), and nitrogen dioxide (NO2) as well as some selected meteorological parameters such as global solar radiation (SR), air temperature (AT), relative humidity (RH), wind speed (WS), and wind direction (WD) were incorporated in this analysis. The data obtained from real-time sensor based continuous ambient air quality monitoring stations which are established at Limbayat and Varachha, situated in Surat city, India are used in this study.. O3 data were distributed according to the four seasons owing to variations in the Indian climatic conditions. The occurrence of peak O3 level in the summer afternoon at around 5 p.m. proved the well-known fact of interconnection among temperature, solar radiation, and increment in O3 concentration. Regardless of long-range transformation and stratospheric intrusion, ozone was propagated based on only a single phenomenon, i.e., chemical reaction occurring between key pollutants manifested with large variances in the first two principal components (PCs). WS and WD were found to be the least influencing parameters using Pearson’s correlation coefficient. CO and NO The potencies of CO and NO were remarkable either in the first or second PC observed at both locations with more than 45% concentration, which alluded that the main source of O3 was urban transportation and AT contributed with weightage 50% in PC ascertained key role of photolysis process in the O3 formation.