Characteristics of haze weather in Chongqing, China and its determinants analysis based on automatic monitoring stations

Özet

Statistical analyses were carried out on the characteristics of haze weather and their relation with air quality and meteorological factors using data recorded by the national air quality and meteorological monitoring network of Chongqing, China in 2013. The results showed that the hourly occurrence rate of haze in Chongqing was 81.3% and that 67.2% of the total number of haze hours was at the level of mild to light haze. Haze was more likely to occur in autumn and winter (67.2% of the total number of hours; occurrence rate 97.5%) and was more likely to occur between 22:00 and 10:00. Haze mainly occurred when the wind speed was 50%. Haze rarely occurred when the wind speed was >3.0 m s1 and the relative humidity was 75 mg m3 , the occurrence rate of haze was 100.0%. The mean value of r(PM2.5)/r(PM10) during the hours of haze was 72.9%, 17.7% higher than that at other times. The number of hours with air pollution accounted for 48.8% of the total number of hours, far less than the occurrence of haze. When the ambient air quality was excellent or good, haze was present in 65.4% of hours. We suggest that there are differences between the assessment of air quality and the definition of haze used in China. The relationship between haze and air quality would be better matched if we used the World Meteorological Organization's definition of haze (visibility < 5.0 km)