我国北方秋冬季节的空气重污染过程已经成为影响人们生活的重大环境事件,不仅受到公众和科研工作者的广泛关注,也已成为各地各部门政策制订者最为重视的关键问题之一.针对众说纷纭的空气重污染过程的形成机理、治理方案、控制对策等,利用2013-2016年秋季(9-11月)中国环境监测总站公布的逐时空气质量监测数据,重点对北京奥体中心站的空气重污染过程的演变进行了分析.结合中国气象局发布的天气形势分析图,系统地分析了我国4 a来秋冬季节出现大范围空气重污染过程的气候背景.结果表明:秋季我国东北和华北地区出现持续时间长、影响范围广的空气重污染过程,除了排放源的影响之外,天气形势同样起着重要作用.2013-2016年秋季北京奥体中心的PM2.5污染状况仍以优良天气为主,其间中度及以上污染的持续时间虽然不长,但其影响[高ρ(PM25)]也不容忽视.秋季北京奥体中心ρ(PM25)日均值超标(二级)日数占25.8％,其中2014年最为严重,超标日数达44 d,占37.4％.通过对空气重污染过程与我国传统节气的对比分析发现,入秋后我国北方首次出现持续48 h以上的空气重污染过程分别是在秋分和寒露两个节气,而最严重的空气重污染过程则出现在寒露和霜降两个节气.从时间序列来看,4 a来北京奥体中心ρ(PM2.5)没有特别显著的改善,优良时数占60％左右,而中度以上的污染时数则维持在25％左右,但严重污染事件[ρ(PM2.5)≥250 μg/m3]的有效时数则有明显的变化.此外,白天污染物的浓度明显低于夜晚.研究还发现,西伯利亚高压指数的异常偏低往往会导致持续时间长、影响范围广和污染强度强的重度污染事件.%Heavy pollution has become a major environmental event affecting people's lives in North China during autumn and winter.Not only an increasing nunber of the public and research workers but also all localities and departments pay attention to heavy pollution.According to the heavy pollution public opinions are divergent.formation mechanism,control scheme,control measures,air quality monitoring data released by Chinese Environmental Monitoring Center between 2013 and 2016 in autumn was analyzed,which focus on the evolution of heavy pollution in Beijing Olympic Sports Center station.Combined with the synoptic situation released by China Meteorological Administration,we carried out systematic analysis of the 4 years autumn season east wide range of heavy pollution process in our country's weather and climate background,pointed out that the heavy pollution process lasted for a long time,the impact of a wide range of autumn in Northeast and North China,in addition to the impact of emission sources,the weather situation also plays an important role.PM2.5 pollution situation of Beijing Olympic Sports Center is still in good weather,but the duration of moderate pollution although not long,but its influence (high ρ (PM2.5))could not be ignored.2013-2016 in the autumn of Beijing Olympic Sports Center (PM2.5) the average daily values exceed the standard (level two),the proportion was 25.8％,2014 was the most serious,exceed the standard number of days up to 44 days,exceed the standard rate of 37.4％.By comparison of the heavy pollution process and China's traditional solar term analysis,after the fall of North China for the first time more than 48 hours of heavy pollution in autumnal equinox and cold dew two solar term,and heavy pollution in the most serious appear in the cold dew and first frost two solar term.From the time series,the 4 year of the Beijing Olympic Sports Center ρ(PM2.5) did not change dramatically so excellent,when the ratio of the number of around 60％,and moderate pollution when the number is maintained at about 25％.But the serious pollution incidents (≥ 250 μg/m3) the effective hours are obvious changes.In addition,daytime pollutant concentrations were significantly lower than night.The study also pointed out that abnormally low Siberia high pressure index often leads to serious pollution events with long duration,wide influence and strong pollution intensity.
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