江门市城区臭氧浓度变化特征及气象影响因素分析

VARIATION CHARACTERISTICS AND METEOROLOGICAL FACTORS OF OZONE CONCENTRATION IN THE URBAN AREA OF JIANGMEN

关键词:  臭氧  气象因子  聚类分析

Key words:  Jiangmen  O3  meteorological factor  cluster analysis

摘要:

基于2015—2017年广东省江门市城区臭氧浓度监测数据和气象观测数据，结合应用统计分析、聚类分析等方法，分析了江门臭氧浓度特征及气象影响因素，探讨了2017年江门臭氧严重超标的气象成因。2015—2017年，江门臭氧污染程度逐年加重，秋季臭氧浓度均值高于其它季节；37%的臭氧浓度超标日与西北太平洋或南海热带气旋活动有关，显著高于其它天气类型下超标日占比。臭氧浓度与白天气象要素相关性高于夜间，对臭氧浓度影响较大的气象要素有日照、相对湿度、气温。聚类分析得到6类气流轨迹，当气流轨迹为偏东(陆地)和偏北路径时，其受体臭氧浓度均值和污染气流轨迹占比显著高于平均值。2017年臭氧严重超标的气象成因是达到利于臭氧生成的气象条件阈值时数和日数显著高于以往，且途经江门以北和以东陆地的气流数目明显多于以往。

Abstract:

This study analyzes the characteristics of ozone concentration and its correlation with meteorological factors, as well as the cause of higher ozone concentration in Jiangmen in 2017 based on hourly ozone concentration data and meteorological observation data in Jiangmen urban area from 2015 to 2017, with the methods of statistical analysis and cluster analysis. The results show that the averaged ozone concentration in Jiangmen increased year by year during 2015—2017, and the seasonal variations in ozone show the highest averaged concentration in autumn and lower averaged concentration in winter and spring. Statistics indicate that 37% of ozone pollution events are related to tropical cyclone activity in the Western Pacific or the South China Sea. The correlation between ozone concentration and meteorological factors in the daytime is higher than that at night. The meteorological elements such as sunshine, humidity, and temperature have greater impact on ozone concentration. Cluster analysis shows six types of backward trajectories. Receptor has higher averaged ozone concentration when the airflow comes from eastern (from inland) and northern path. The excessive hours and days with favorable meteorological conditions for ozone production contribute to higher ozone concentration of Jiangmen in 2017, and cluster analysis shows that the number of airflow trajectories whose receptor has higher averaged ozone concentration is a higher than that in previous years.