The diurnal variations in ozone concentrations in the summer were studied using the temperature, wind speed and direction, total cloud cover, and solar radiation intensity data collected in Langfang, China. The ratio of volatile organic compounds to nitrogen oxides (VOCs/NOx) and the EKMA curve were studied to analyze the sensitivity of ozone formation. The results showed that:① The ozone generation rate and ozone concentrations were positively correlated with the solar radiation intensity with Pearson correlation coefficients of 0.61 and 0.48, respectively. Both the ozone generation rate and the solar radiation intensity reached their peak at about 12:00, while the ozone concentration reached its peak at about 16:00, which lagged behind the peak of the solar radiation intensity by 4 h. ② The correlation coefficient between the ozone generation rate and the temperature was 0.44, between the ozone concentration and temperature was 0.68. The ozone generation rate and ozone concentrations were inversely correlated with total cloud cover with correlation coefficients of -0.24 and -0.45, respectively. ③ The ozone concentrations in Langfang were high when the winds were from the west, south, or southeast. ④ The ozone concentrations in Langfang were more sensitive to VOCs than to NOx; thus, they can be reduced efficiently by controlling the VOCs emissions.
Keywords: Langfang; NOx; O3; VOCs; control area; meteorological factors.