| 汾渭平原吸收性气溶胶时空演化及潜在源区分析 |
| 摘要点击 2929 全文点击 797 投稿时间：2020-10-17 修订日期：2020-12-05 |
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| 中文关键词 吸收性气溶胶 潜在源区 后向轨迹 时空演化 汾渭平原 |
| 英文关键词 absorbing aerosol potential sources backward trajectory tempo-spatial evolution Fenwei Plain |
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| 中文摘要 |
| 在绿色发展理念的带动下，全国多地的空气质量逐渐改善，但汾渭平原大气污染程度逐年走高，颗粒物污染尤为严重.利用OMI/Aura OMAERUV L2气溶胶数据集和PM2.5站点数据，采用空间自相关分析及后向轨迹模型等方法，探索2005~2019年汾渭平原吸收性气溶胶的时空演化过程，揭示其高值极主导类型以及污染物传输路径和潜在源区.结果表明：①2005~2019年汾渭平原吸收性气溶胶指数（absorbing aerosol index，AAI）年均值波动上升，2006、2013和2017年为汾渭平原AAI高值转折点，年均值均大于0.63；西安和临汾AAI空间稳定性较差为高高聚集极点，在15年间高高聚集区域面积增长15.3%，空间分布更加集中，形成由西安和临汾两极相连的条带状分布区域，占区域总面积的24.2%；低低聚集区域面积锐减6.2%，转变为无特征区域.②汾渭平原AAI冬季数值最高、覆盖区域最广，在临汾极和西安极突破0.8，研究区AAI大于0.6的区域占比91.5%，其次为春季（AAI>0.4）、秋季（AAI>0.3），夏季全境低值.汾渭平原AAI高值受大气扩散条件、气温和降水量变化影响显著.③利用后向轨迹和潜在源贡献模型得出西安极和临汾极污染物的远距离输送气团来自西北方向，近距离输送气团来自偏东和偏南方向，结合源区下垫面类型确定两个远距离沙尘传输源区（西北风源、北风源）、两个碳质源区（东风源和南风源）和一个沙尘和碳质共同作用源区（黄土高原源）.其中西北风源、黄土高原源和南风源对西安极影响显著，东风源和黄土高原源对临汾极影响显著，临汾极虽受一定程度西北风源和北风源沙尘影响，但影响较小，结合CO空间分布和其与AAI相关性系数的空间分布得出，临汾极吸收性气溶胶为碳质主导，西安极为沙尘和碳质共同作用. |
| 英文摘要 |
| Air quality has gradually improved in many parts of China; however, air pollution is become more severe in the Fenwei Plain. Using OMI/Aura OMAERUV L2 and PM2.5 data, spatial autocorrelation analysis and back trajectory modeling were used to explore the spatio-temporal patterns of absorptive aerosols over the Fenwei Plain, and the dominant types, transmission paths, and potential source areas were identified. The main results can be summarized as follows:① Annual mean absorbing aerosol index (AAI) values increased between 2005 and 2019, with high period occurring in 2006, 2013, and 2017, with values exceeding 0.63. Xi'an and Linfen were identified as a ‘high-high’ cluster, with AAI showing poor spatial stability and a 15.3% increase in area over the past 15 years. In contrast, the area connecting Xi'an and Linfen, which occupies 24.2% of the total area of the region, was identified as a ‘low-low’ cluster, with a sharp drop of 6.2% in area; ② The Fenwei Plain has high AAI values across a large area in winter, exceeding 0.8 in Linfen and Xi'an, and 91.5% of the study area exceeding 0.6. Values were lower in spring (AAI>0.4) and autumn (AAI>0.3), with the lowest values occurring in summer. The atmospheric diffusion conditions in spring, autumn, and winter are poor, associated with anticyclonic high-pressure events. The observed high AAI values were significantly affected by atmospheric diffusion conditions, temperature, and precipitation; ③ Back trajectory and source contribution modeling showed that long-range transport of air masses from Xi'an and Linfen occurs from the northwest, and short-range transport air masses occurs from the east and south. Two long-range sand and dust source areas were determined (with northwestern and northern wind sources); two carbon source areas were identified (with eastern and southern wind sources); and one combined sand and carbon source area was identified (from the Loess Plateau). Of these sources, the northwestern wind source, the Loess Plateau, and the southern wind source have significant influence in Xi'an, and the eastern wind source and the Loess Plateau have a significant impact on Linfen. Linfen is little affected by the northwestern wind source and the dust from the northern wind source. Based on the spatial distribution of CO and its correlation with AAI, it is concluded that cardon in the dominant absorbent aerosol in Linfen dust and carbon are most important in Xi'an. |
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