The role of local meteorology on ambient particulate and gaseous species at an urban site of western India

Abstract

Dependencies of ambient concentrations of PM2.5, PM10, CO and O3 on meteorology in Udaipur of India have been discussed based on the measurements from April 2011 to March 2012. PM2.5 and CO were highest in winter due to lower PBL depth and calm winds while PM10 and O3 were highest in the pre-monsoon season due to convective activities. Lower wind regimes (<2 km hr−1), highest PM2.5 and CO were 47 ± 20 μg m−3 and 441 ± 170 μg m−3 indicating the accumulation of pollutants while lower levels of PM2.5 (36 ± 16 μg m−3) and CO (317 ± 114 μg m−3) indicated the impact of dispersion at higher wind regimes. A positive slope of ∆PM10/∆WS = 4.4 μg m−3/km hr−1 indicates predominance of natural sources of coarser particles. Higher concentrations of PM2.5 and CO with correlation coefficient (0.42 and 0.52) under high RH and low temperature during winter season indicate the strong temperature inversion. Negative correlation between PM10 and RH (r = −0.70) during monsoon indicates the role of rainfall in wetting the soil reducing its aerosolization and particle washout. Rainfall was significant for PM10 (~53% reduction) than those observed for PM2.5 and CO. Overall, this study suggests the strong influence of meteorology in the variation of air pollutants.