APEC会议前后北京地区PM2.5污染特征及气象影响因素

为分析APEC会议前后北京地区PM_2.5变化特征,利用中国科学院大学雁栖湖校区超级站在2014年10—12月的连续观测数据,对APEC会议前后北京地区污染物分布及变化特征、气象影响因素和气团传输路径特征进行了分析. 结果表明:APEC会议期间北京地区减排效果显著,ρ(PM_2.5)平均值比会前下降了60.5%. 气象条件对污染物扩散起到积极作用,APEC期间平均风速为1.40 m/s,平均相对湿度为31.9 %,近地面气象条件优于APEC会前、会后. 北京地区受到外来污染物输送的影响,在2.00~3.00 m/s的南风下易发生来自南部地区的PM_2.5和SO₂输送. APEC会议期间北京地区主要受来自西北地区的高速、高海拔气团控制,其出现频率为39.6%,远低于APEC会前 (15.9%)和会后(20.8%),而来自南部地区的低速、低海拔污染气团的出现频率仅为2.1%,扩散条件总体良好. 研究显示,除了减排措施有效削减了污染物排放以外,有利的气象条件也是APEC会议期间北京地区保持良好空气质量的重要因素. 

Variations of PM2.5 Pollution and Related Meteorological Factors Before and After the 2014 APEC Conference in Beijing

Abstract: To analyze the variation characteristics of atmospheric pollution before and after the Asia-Pacific Economic Cooperation (APEC) conference in Beijing in 2014,this study investigated the temporal variation of atmospheric pollutants in Beijing and its relation to meteorological factors as well as air mass transport pathways in a supersite on the Yanqi Lake campus of the University of Chinese Academy of Sciences from October to December 2014. During the APEC period,Beijing experienced a significant reduction of PM_2.5- the average PM_2.5 decreased by 60.5% compared with that before the APEC period. The meteorological conditions played important roles in the dispersion of air pollutants. During the APEC period,the average wind speed was 1.4 m/s and the average relative humidity was as low as 31.9%,which were much better than those before and after the APEC period. Beijing is vulnerable to air pollutants from long transport,and the pollutants of the southern area were more likely to be transported to Beijing under an average wind speed of 2.00-3.00 m/s. During the APEC period,Beijing was mainly affected by the clean air masses that came from the northwestern regions with high moving speeds and altitudes,indicating the meteorological conditions were favorable for the dispersion of pollutants. The clean air masses accounted for 39.6% of the total air masses that arrived at Beijing,lower than that before and after APEC period,which were 15.9% and 20.8%,respectively,while the polluted air masses coming from the southern regions with low moving speeds and altitudes accounted for only 2.1%. In conclusion,the advantageous meteorological conditions were also an important factor contributing to good air quality during the APEC period besides the strict control of emissions.