Abstract: Based on the ozone mass concentration data in Ningxia from 2015 to 2018, the variations of O3 mass concentration in five cities of Ningxia were analyzed and compared, and the influences of airflow on O3 mass concentration in five cities of Ningxia were discussed by using back trajectory cluster analysis method and the global data assimilation system. The results show that the 90% quantile of O3 mass concentration in Shizuishan was the highest (159 μg·m-3), followed by Yinchuan (154 μg·m-3), Zhongwei (149 μg·m-3), Wuzhong (137 μg·m-3), and Guyuan (132 μg·m-3) during 2015-2018. In the past four years, the O3 mass concentration in Shizuishan decreased slightly, while that in other four cities increased. The days on which  primary pollutants was O3 was 124 days in Shizuishan, 119 days in Zhongwei and 103 days in Yinchuan. The days on which primary pollutants was O3 and air quality was good and  light pollution increased in all 5 cities. Except for Guyuan, the frequency of O3 pullution processes with 6 d and 7 d  duration increased in other cities, especially in Yinchuan and Zhongwei. For Shizuishan, Yinchuan and Wuzhong, the middle-distance and short-distance northwest airflow accounted for the highest percentage of the total airflow trajectory, followed by the southeast airflow and the north airflow. For Zhongwei and Guyuan,the percentage of the southeast airflow  was the highest, followed by the short-distance northwest airflow, and then the middle-distance and long-distance northwest airflow. The northern airflow from central Mongolia, central and western Inner Mongolia, across the northern and central Ningxia was the most important transport path affecting the O3 mass concentration, while the southeastern airflow from south central Shaanxi, northeastern Gansu and middle east Ningxia was the most important transport path affecting the ozone mass concentration in Shizuishan, Yinchuan, Wuzhong and Zhongwei.

Key words:
Key words: ozone pollution, transport path, back trajectory cluster analysis, Ningxia

摘要： 基于2015—2018年宁夏O3质量浓度资料，分析比较宁夏5市O3质量浓度变化特征，结合全球资料同化系统（GDAS）数据，采用后向轨迹聚类分析法，探讨影响宁夏5市O3质量浓度的气流轨迹特征。结果表明：2015—2018年宁夏石嘴山年均O3质量浓度90%分位数最高，为159 μg·m-3，银川、中卫和吴忠分别为154、149和137 μg·m-3，固原最低为132 μg·m-3；近4 a石嘴山O3质量浓度略下降，其他4市普遍增高；首要污染物为O3的天数石嘴山最多(124 d)，中卫次之(119 d)，银川第3(103 d)；各市首要污染物为O3且空气质量为良、轻度污染的天数普遍增多；除固原外，其他4市持续6 d、7 d O3污染过程次数均增加，其中，银川和中卫增加最明显。石嘴山、银川和吴忠三市，中、短距离西北气流总占比最高，其次是东南气流，再次是北方气流；中卫和固原两市，东南气流占比最高，其次是短距离西北气流，再次是中、长距离西北气流；来自蒙古国中部、内蒙古中西部，横穿宁夏北部和中部的北方气流是影响固原O3质量浓度的最重要输送路径，源自陕西中南部、甘肃东北部、宁夏中东部的东南气流是影响石嘴山、银川、吴忠和中卫O3质量浓度的最主要输送路径。

关键词:
臭氧污染, 输送路径, 后向轨迹聚类分析, 宁夏