| 北京地区近35年大气污染扩散条件变化 |
| 摘要点击 4415 全文点击 1771 投稿时间：2016-10-22 修订日期：2017-01-17 |
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| 中文关键词 污染扩散条件 较大偏北风 垂直运动 大气容量指数 边界层高度 |
| 英文关键词 pollution diffusion conditions great north wind speed vertical motion atmospheric capacity index boundary layer height |
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| 中文摘要 |
| 本文使用NCEP（National Center for Environmental Prediction）再分析月平均数据（2.5°×2.5°）、1980~2015年北京地区（54511站点）的探空数据及温、压、湿、风、降水数据，分析了近35年来北京地区大气污染扩散条件的变化.主要结论有：1980~2015年，大气不断增温，1990年以后逆温明显，大气较为稳定，冷空气到达北京上空后对下层的影响减弱，3级以上偏北风频率减少，近地层辐合.同时，2000年以后中高层下沉运动位置不断下压，低层上升运动加强，低层上升运动被限制在边界层以内，这样会导致垂直扩散条件转差.1980~1989年大气容量指数较为稳定，1990~1999年大气容量指数出现波动，而2000~2015年大气容量指数呈现明显减小的趋势.总体来看，近35年大气自身的容纳能力呈现一个平缓的下降趋势.1980~1989年春季和冬季大气容量指数较大，1990~1999年春季和夏季大气容量指数较大，但是2000年以后，无论哪个季节，大气自身的容纳能力都是在减弱的，季节性差异变小.边界层高度在这30多年来都是春季和夏季较高，秋季和冬季明显降低. |
| 英文摘要 |
| In this paper, the monthly average of NCEP(National Center for Environmental Prediction)reanalysis data (2.5°×2.5°),the sounding data, and conventional observation data in Beijing (54511 station) were used to analyze the atmospheric pollution diffusion conditions in Beijing in recent 35 years. The main conclusions were:in 1980~2015, the whole layer was warmer. After 1990, the temperature inversion phenomenon was obvious, and the whole air was stable. The cold air's less effect on the lower layer, lower frequency of great north wind speed and surface layer's convergence led to the rising of pollution concentration. The location of sink motion at the high level was lower and that of the ascending motion at the low level was higher. This led to the constriction of the ascending motion below the boundary layer, worsening the pollution diffusion condition. In 1980~1989, the atmospheric capacity index was steady, while in 1990-1999,it fluctuated obviously and after 2000,it declined. In general, the atmospheric capacity presented a gentle decline. In spring and winter of 1980-1989, as well as spring and summer of 1990-2015, the atmospheric capacity was better. After 2000, the atmospheric capacity was decreasing compared to the last 20 years no matter in which season, and the difference of atmospheric capacity in seasons diminished. The boundary layer was higher in spring and summer, and lower in fall and winter in recent 35 years. |
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