Surface ozone concentrations and local cloud cover at an urban, tropical site in the Southern Hemisphere

Surface ozone plays a key role in the photochemistry of the low troposphere, being associated with health and environmental problems. It results from a pool of reactions involving natural and anthropogenic pollutants, solar radiation, and the atmospheric condition. In this study, 12-months of recent measurements of surface ozone concentration (SOC) are presented for an urban, tropical site in Brazil. An analysis of the SOC dependence on the local cloud cover is introduced. Daily maxima of the one-hour averaged data (1-h SOC) ranged from 8.7 to 96.1 ppbv and averaged 38.1±13.7 ppbv, while the monthly averages of the daily maxima of 1-h SOC varied from 24.5±8.8 ppbv in early fall to 46.7±9.3 ppbv in late winter.