成都市臭氧污染特征及气象成因研究

Ozone temporal variation and its meteorological factors over Chengdu City

为研究成都市臭氧(O3)污染特征及其气象成因,对2014—2016年成都市6个国控环境监测站和同期气象台站逐小时地面观测数据进行了研究分析.结果表明:近4年来成都市O3污染日趋严重,O3年均浓度不断上升,较2013年升高51.2μg·m-3.O3浓度存在明显的季节变化特征:春、夏季较高,秋、冬季则较低,且各季节O3浓度变化具有很强的长期持续性特征.O3浓度日变化特征呈明显的单峰型分布,8:00出现最低值,15:00—16:00出现峰值,超标时段主要出现在13:00—17:00.O3浓度变化与紫外辐射、气温呈正相关关系,与相对湿度、风速呈负相关关系,且当紫外辐射大于12 MJ·m-2、气温高于15℃、相对湿度低于65%、西风或偏东北风控制时,成都市容易发生高浓度O3污染.

The observation data from 6 national environmental monitoring sites and a meteorological site in Chengdu during 2014 to 2016 were analyzed to study the temporal variation of surface ozone concentration and its meteorological factors. The situation of ozone pollution became worse in Chengdu in recent years,which showing obvious seasonal variation： higher in spring and summer,lower in autumn and winter. In all four seasons,the ozone concentration had a strong long-term persistence. The daily variation of ozone concentration showed a unimodal distribution,with minimum value appeared at 8： 00 and maximum value appeared at about 15： 00 to16： 00. The ozone concentration was positively correlated with ultraviolet radiation and temperature,while negatively correlated with relative humidity and wind speed. The ozone concentration was more likely to stay in excessive condition when the ultraviolet radiation was higher than 12 MJ·m^-2,the atmospheric temperature was higher than 15 ℃ and the relative humidity was lower than65%. The ozone concentration was impacted by wind direction and wind speed to some extent. The lower ozone concentration was found under north wind while higher ozone concentration was observed under west or northeast wind,which indicated that the northeast and west main industrial zone in Chengdu City and the wind-conveying transmission of high ozone concentration is also the cause of elevated ozone concentration.