Assessment of ozone variations and meteorological effects in Beijing

Based on the observation data of surface ozone and its precursors at an urban site in Beijing from August 2004 to August 2005, the ozone concentrations and their temporal variation characteristics were studied. The correlation between ozone and related meteorological parameter was analyzed. The results showed that ozone pollution during summer was very serious in Beijing because of local photochemical reactions. Diurnal variations of ozone concentrations exhibited with the characteristic of a single peak, and showed the peak often appear at about 15:00 in the early afternoon and low concentrations during late night and early morning, while the precursors show high concentrations during night and early morning and low concentrations during daytime. The seasonal variations in NOx and CO showed high concentrations in winter and low concentrations in summer. Both temperature and wind speed have significant positive correlation with ozone. Relative humidity has a significant negative correlation with ozone. Ozone concentrations correlated well with temperature in summer and with wind speed in winter. The distant transport associated with southeastern, southern and western winds contributes substantially to the ozone because the air mass was polluted. The main relationships we could observe in these analyses were then used to obtain a regression equation linking diurnal ozone concentration in summer with meteorological parameters.