北京地区空气重污染下雾凇和偏东风对PM_(2.5)清除作用  

Scavenging Effect of Rime and East Wind on PM_(2.5) Under Air Heavy Pollution in Beijing

作　　者：孙兆彬[1,2] 廖晓农 王占山[3] 李梓铭 赵秀娟 花丛 

机构地区：[1]中国气象局北京城市气象研究所,北京100089 [2]京津冀环境气象预报预警中心,北京100089 [3]北京市环境保护监测中心,北京100048 [4]国家气象中心,北京100081

出　　处：《环境科学》2016年第10期3679-3685,共7页Environmental Science

基　　金：国家科技支撑计划项目(2014BAC16B04;2014BAC23B03;2014BAC23B01);中国气象局预报员专项(CMAYBY2016-003);国家电网公司总部科技项目(8KE000M15011)

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1 200-1 800 m,PM2.5被抬升至高层清除.In order to study the scavenging effect of rime and east wind on the concentrations of PM2.5in Beijing during the air heavy pollution,PM2.5concentration 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 1 the removal of PM2.5by 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 PM2.5decreased; 2 the 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 PM2.5was 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 PM2.5capacity became small,which was beneficial to increase the concentration of PM2.5; 3 the 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; 4 after occurrence of east wind,along with the ascending motion to m·s-1 1magnitude,the mixed layer height increased to1 200-1 800 meters,and PM2.5was uplifted to top layer and cleaned.

关 键 词：PM2.5 雾凇 偏东风 上升运动 风切变 

分 类 号：X513[环境科学与工程—环境工程]