Correlation between Near-surface Ozone Concentration and Meteorological Conditions in Cangzhou

Based on the ozone monitoring data and meteorological data of Cangzhou from 2013 to 2018, the characteristics of ozone pollution and the influence of meteorological factors on ozone concentration in Cangzhou were analyzed. The results showed that the ozone concentration in Cangzhou had an obvious seasonal variation, with the highest in spring and summer. The days of ozone exceeding the standard value were also concentrated in spring and summer. The ozone concentration and days of ozone exceeding the standard value were increasing year by year. Among all meteorological factors, the air temperature had the strongest correlation with ozone. Higher air temperature was a necessary condition for the occurrence of ozone in Cangzhou city, and the higher the temperature, the more likely to lead to higher concentration of ozone pollution; In most cases, ozone concentration was negatively correlated with relative humidity. When the relative humidity was greater than 50%, the higher the relative humidity was, the lower the average ozone concentration and the 90th percentile ozone concentration were. The precipitation level and the precipitation nature both had a significant effect on ozone concentration. When the precipitation on the day was more than 10 mm, most of the precipitation was convective precipitation in spring and summer, and the ozone concentration was higher. Wind direction and speed affected the horizontal transmission and vertical diffusion of ozone pollutants, especially in winter and spring. When ozone pollution occurred, the prevailing wind changed from west-southwest wind or east-northeast wind to south-southwest wind, and as the wind speed increased, the average ozone concentration increased obviously. The increase of ozone concentration in spring and the increase of mixing layer height were caused by the increase of wind speed have important relationships. Particulate matter indirectly affected ozone concentration by affecting the Near-surface meteorological elements. From May to October, when ozone pollution was high and particulate concentration was relatively low, the meteorological characteristics were high temperature and strong sunshine, which were conducive to the occurrence of various photochemical reactions in the atmosphere. In autumn and winter, particulate matter affected the average ozone concentration by affecting the formation of foggy weather. Ozone pollution days in Cangzhou were accompanied by the changes of a series of meteorological conditions, including sunny days, higher mixing layer height, increasing wind speed, lower relative humidity and rising temperature. The end of pollution was accompanied by the opposite weather changes.