Surface ozone variability over western Maharashtra, India

We present the simultaneous field measurements of surface ozone (O3) made at the five different sites of western Maharashtra, India for the period between 2001 and 2005. Seasonal variation in O3 shows a pronounced maximum concentration about 40-50 ppbv in the summer and winter season in the urban site and similar concentration of O3 is also observed in the rural site despite less emission of precursor gases. The increase in O3 concentration is observed in the sugar factory premises during sugarcane crushing period. Diurnal patterns in O3 do not show daytime in situ photochemical buildup at high altitude mountain site. The higher O3 concentration is observed in the morning hours near to the dam than at urban and rural sites. These variations in O3 indicate that the local pollutants are major contributors to the O3 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.