| 北京地区空气重污染下雾凇和偏东风对PM2.5清除作用 |
| 摘要点击 3242 全文点击 1561 投稿时间：2016-03-30 修订日期：2016-05-04 |
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| 中文关键词 PM2.5 雾凇 偏东风 上升运动 风切变 |
| 英文关键词 PM2.5 rime east wind upward movement wind shear |
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| 中文摘要 |
| 为了研究空气重污染过程期间雾凇和偏东风对北京地区PM2.5浓度的影响，利用2015年12月19~27日山区和平原多站PM2.5浓度数据、常规气象数据、风廓线数据、激光雷达气溶胶消光系数资料，分析了雾凇和偏东风对PM2.5的清除机制. 结果表明：①雾凇对PM2.5的清除是不同于偏北风和降水天气的一种清除机制，在过冷却的条件下，雾滴触碰树枝、电线后凝结为固体，形成雾凇，PM2.5浓度下降；②偏东风是北京地区一类特殊风系，当偏东风随高度减小时，能够形成较强的上升运动，将PM2.5从近地层抬升至高层，随着高层较大的西风，被带入下游而清除掉；当偏东风随高度增大时，容易形成弱的下沉运动，而当此下沉运动不能够抵达地面时，近地层对PM2.5容量变小，有利于PM2.5浓度的升高；③偏东风对PM2.5的清除能力取决于两点，一是偏东风所形成的上升运动的强度与发展的高度，二是偏东风所形成上升运动的起始高度，上升运动的起始高度越低对PM2.5的清除效果越明显；④偏东风出现后，伴随着上升运动达到m·s-1的量级，混合层高度升高至1200~1800 m，PM2.5被抬升至高层清除. |
| 英文摘要 |
| In order to study the scavenging effect of rime and east wind on the concentrations of PM2.5 in Beijing during the air heavy pollution, PM2.5 concentration data of some mountains and plains stations was used, together with meteorological data, wind profile data, aerosol extinction coefficient radar data collected during December 19 to 27, 2015, to analyze the clearance mechanisms of rime and east wind on PM2.5.The results showed that ①the removal of PM2.5 by rime was a different mechanism from that by the north wind and rainy weather, in the cooling conditions, the droplets touched the branches, wire for solid condensation, leading to formation of rime, and the concentration of PM2.5 decreased;②the east wind is a special kind of wind in Beijing area, when easterly wind decreased with height, a strong upward motion could be formed, and the PM2.5 was uplifted from the surface layer to the top, while with larger westerly wind in top, it was removed into downstream and cleaned; when east wind increased with height, a weak downward movement was easy to form, and when this sinking motion could not reach the ground, the surface layer of PM2.5 capacity became small, which was beneficial to increase the concentration of PM2.5;③the PM2.5scavenging ability of east wind depended on two points, one was the strength and development of upward movement of the height formed by the east wind, and the second was the initial height of uplifted motion formed by east wind, the lower the origin of the ascending motion height, the more obvious the removal of PM2.5;④after occurrence of east wind, along with the ascending motion to m·s-1 magnitude, the mixed layer height increased to 1200-1800 meters, and PM2.5 was uplifted to top layer and cleaned. |
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