Surface ozone variability over western Maharashtra, India

We present the simultaneous field measurements of surface ozone (O-3) made at the five different sites of western Maharashtra, India for the period between 2001 and 2005. Seasonal variation in O-3 shows a pronounced maximum concentration about 40-50 ppbv in the summer and winter season in the urban site and similar concentration of O-3 is also observed in the rural site despite less emission of precursor gases. The increase in O-3 concentration is observed in the sugar factory premises during sugarcane crushing period. Diurnal patterns in O-3 do not show daytime in situ photochemical buildup at high altitude mountain site. The higher O-3 concentration is observed in the morning hours near to the dam than at urban and rural sites. These variations in O-3 indicate that the local pollutants are major contributors to the O-3 concentrations at the urban and rural sites, while regional transport plays a role at high altitude mountains site. Model simulations using a Eulerian photochemical model have also been carried out with the available data. The comparison of model results with observation shows that a diurnal and seasonal pattern is in good agreement. (C) 2008 Elsevier B.V. All rights reserved.