Relationship of Surface Ozone (O3) with its precursors and meteorological parameters over New Delhi, India

Abstract

In the present study, continuous measurements of Surface Ozone (O3), Oxides of Nitrogen [NOx (NO+ NO2)] and carbon monoxide (CO), monitored at five different locations in Delhi National Capital Region have been studied for the period 2013-2019. The five monitoring locations used are namely IMD Lodi Road, IGI Airport Palam, CV Raman Dheerpur, CRRI Mathura Road, and NCMRWF Noida. The relationship between NO, NO2, and surface O3 as a function of NOx has been examined during daylight hours (0500 hrs IST to 1900 hrs IST) and chemical coupling of the three species, i.e., NO, NO2 and O3 have been studied. The ground-level concentration of Ozone has been found to decrease with increasing NOx concentration during the daytime. The variations in daylight hourly average concentrations of oxidants [OX = NO2 + O3] with the concentration of [NOx] have been studied to examine the contributing pollution sources of oxidants at all the study sites. The average rate of change of surface O3 concentrations (dO3/dt) has been examined at all five locations. The monthly and diurnal variation of oxidants [OX] at all the study locations has shown a strong positive correlation with temperature whereas a negative correlation with humidity.