Surface ozone variation at Bhubaneswar and intra-corelationship study with various parameters

This paper summarizes the results of year long (December 2009 to January 2011) continuous measurements of daytime (0700-1745) ozone (O-3) in the ambient air and related meteorological parameters at Bhubaneswar (21 degrees 15'N-85 degrees 15'E), Odisha. The seasonal variation shows distinct daytime ozone maxima during winters with a peak in January (similar to 85 ppbv), a slight increase (similar to 38 ppbv) in June and lowest in August (similar to 20 ppbv). The backward trajectory analysis during winter months suggests long distance transport of airmass from mainly Indo-Gangetic Plains (IGP) and western part of Indian peninsula, a major industrial hub. In other seasons, wind reaches the observation site from less polluted landmasses and the Bay of Bengal, thereby considerably reducing the pollution load. On the contrary, ozone build-up was found to be maximum and minimum in pre-monsoon and monsoon, respectively. An anti-weekend ozone effect (similar to 5 ppbv) was observed in winter. Paired t-test and F-test along with principal component analysis (PCA) were done to determine significance between various components (ozone, precursors and meteorological parameters). The t- and F-test showed significant monthly variation of ozone mixing ratio. The PCA showed that three components explained 79.1% of variances.