Relationships between submicrometer particulate air pollution and air mass history in Beijing, China, 2004-2006
Relationships between submicrometer particulate air pollution and air mass history in Beijing, China, 2004-2006
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DOI：
10.5194/acp-8-6155-2008
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发表时间：
2008-10
影响因子：
6.3
通讯作者：
B. Wehner;W. Birmili;F. Ditas;Zhijun Wu;Min Hu;Xingang Liu;J. Mao;N. Sugimoto;A. Wiedensohler-A.-Wiedenso
中科院分区：
文献类型：
--
作者：
B. Wehner;W. Birmili;F. Ditas;Zhijun Wu;Min Hu;Xingang Liu;J. Mao;N. Sugimoto;A. Wiedensohler-A.-Wiedenso
中国首都北京是全球特大城市之一，经济快速增长的影响导致了复杂的空气污染问题，但这些问题尚未得到很好的理解。本文分析了2004 - 2006年北京市大气颗粒物粒径分布与区域气象输送的关系。一个基本的结果是，在北京的粒子大小分布在很大程度上取决于天气尺度气团的历史。第一种方法的基础上手动回轨迹分类产生的差异颗粒物质量浓度的两个因素之间的四个不同的空气质量类别，包括三个主要的风向加上停滞的空气质量的情况。后向轨迹聚类分析细化了这些结果，总共产生了六个轨迹聚类。除了大尺度风向外，气团的输送速度对北京PM浓度也有重要影响。缓慢移动的气团被证明与地表人为排放的有效积累有关，这是由于在人口稠密的土地上停留时间增加以及垂直稳定性较高。对于6个后向轨迹簇，PM 1质量浓度的差异为3.5倍，平均空气质量速度的差异为6倍，大气能见度的差异为4倍。主要结论是，北京的空气质量不仅受到来自大城市内部的人为气溶胶源的影响，也可根据气象条件，由整个西北平原的来源。
The Chinese capital Beijing is one of the global megacities where the effects of rapid economic growth have led to complex air pollution problems that are not well understood. In this study, ambient particle number size distributions in Beijing between 2004 and 2006 are analysed as a function of regional meteorological transport. An essential result is that the particle size distribution in Beijing depends to large extent on the history of the synoptic scale air masses. A first approach based on manual back trajectory classification yielded differences in particulate matter mass concentration by a factor of two between four different air mass categories, including three main wind directions plus the case of stagnant air masses. A back trajectory cluster analysis refined these results, yielding a total of six trajectory clusters. Besides the large scale wind direction, the transportation speed of an air mass was found to play an essential role on the PM concentrations in Beijing. Slow-moving air masses were shown to be associated with an effective accumulation of surface-based anthropogenic emissions due to both, an increased residence time over densely populated land, and their higher degree of vertical stability. For the six back trajectory clusters, differences in PM 1 mass concentrations by a factor of 3.5, in the mean air mass speed by a factor of 6, and in atmospheric visibility by a factor of 4 were found. The main conclusion is that the air quality in Beijing is not only degraded by anthropogenic aerosol sources from within the megacity, but also by sources across the entire Northwest China plain depending on the meteorological situation.