Typical synoptic situations and their impacts on the wintertime air pollution in the Guanzhong basin, China
Typical synoptic situations and their impacts on the wintertime air pollution in the Guanzhong basin, China
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DOI：
10.5194/acp-2015-710
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发表时间：
2016-06
影响因子：
6.3
通讯作者：
N. Bei;Guohui Li;Rujin Huang;Junji Cao;N. Meng;T. Feng;Sui-xin Liu;Ting Zhang;Qiang Zhang-Qiang-Zh
中科院分区：
文献类型：
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作者：
N. Bei;Guohui Li;Rujin Huang;Junji Cao;N. Meng;T. Feng;Sui-xin Liu;Ting Zhang;Qiang Zhang-Qiang-Zh
抽象。快速的工业化和城市化导致了中国西北部关中盆地严重的空气污染，近几年冬季频繁发生重度雾霾事件。利用NCEP再分析资料，将2013年冬季影响关中盆地的大尺度天气形势分为“北低”、“西南槽”、“东南高”、“过渡”、“东南槽”和“内陆高”6种类型，分析其对关中盆地大气污染的贡献。利用FLEXPART模型模拟了流域典型天气情况下相应的污染物输送模式。除“西南槽”和“东南高压”（定义为有利天气形势）外，其余4种天气形势（定义为不利天气形势）一般都有利于污染物的积累，造成流域空气重污染。与流域中PM2.5（空气动力学直径小于2.5 µm的颗粒物）的测量相关，不利的天气状况对应于高PM2.5质量浓度或空气质量差，反之亦然。同样的分析也被应用到2008-2012年的冬季，这表明该流域主要是在冬季的不利天气形势，导致空气质量差的影响。进一步应用WRF-CHEM模式对2013年冬季典型天气形势进行模拟，模拟结果与相应天气形势的分布和变化基本吻合，说明对该流域天气形势的分类是合理的。逆温、低层水平风速、行星边界层等详细的气象条件，在不利的天气条件下，都对流域的重污染事件有贡献。考虑到冬季不利天气的发生比例，减少排放是减轻关中盆地大气污染的最佳途径。
Abstract. Rapid industrialization and urbanization have caused severe air pollution in the Guanzhong basin, northwestern China, with heavy haze events occurring frequently in recent winters. Using the NCEP reanalysis data, the large-scale synoptic situations influencing the Guanzhong basin during wintertime of 2013 are categorized into six types to evaluate the contribution of synoptic situations to the air pollution, including “north-low”, “southwest-trough”, “southeast-high”, “transition”, “southeast-trough”, and “inland-high”. The FLEXPART model has been utilized to demonstrate the corresponding pollutant transport patterns for the typical synoptic situations in the basin. Except for “southwest-trough” and “southeast-high” (defined as favorable synoptic situations), the other four synoptic conditions (defined as unfavorable synoptic situations) generally facilitate the accumulation of air pollutants, causing heavy air pollution in the basin. In association with the measurement of PM2.5 (particulate matter with aerodynamic diameter less than 2.5 µm) in the basin, the unfavorable synoptic situations correspond to high PM2.5 mass concentrations or poor air quality and vice versa. The same analysis has also been applied to winters of 2008–2012, which shows that the basin was mainly influenced by the unfavorable synoptic situations during wintertime leading to poor air quality. The WRF-CHEM model has further been applied to simulate the selected 6 days representing the typical synoptic situations during the wintertime of 2013, and the results generally show a good agreement between the modeled distributions and variations of PM2.5 and the corresponding synoptic situations, demonstrating reasonable classification for the synoptic situations in the basin. Detailed meteorological conditions, such as temperature inversion, low-level horizontal wind speed, and planetary boundary layer, all contribute to heavy air pollution events in the basin under unfavorable synoptic conditions. Considering the proportion of occurrence of unfavorable synoptic situations during wintertime, reduction of emissions is the optimum approach to mitigate the air pollution in the Guanzhong basin.