Pollution Characterization and Variation of Ground Ozone in Shanghai Central Urban Area

Ground ozone level was yearly monitored continuously in Shanghai Zhabei ambient air in 2005.Results indicated that 2.88% hourly ozone concentration exceeded 160μg/m~3,class 2 of national standard(GB3095-1996),with the largest non-attainment percentage in June while all data in January,February and December matched standard class 2.Diurnal variation of ozone showed that peak value occurred during 12:00～14:00,with distinct characteristics of photochemical pollutionrelate region.The largest diurnal variation range was found in June and the smallest was found in February.The largest ozone monthly-average concentration was observed in May with the largest hourly concentration 350μg/m~3 in May 19,which demonstrated that ozone formation might be impacted by precursor pollution to large extent.The impact of UV light,atmospheric temperature,wind speed,wind direction,precipitation and relative humidity on ozone variation were also studied.The strong correlation of ozone to NO_2/NO ratio was observed in high temperature and sunny days.