2013年春季兰州一次罕见持续浮尘天气过程分析

Analysis of a durative floating dust event over Lanzhou in 2013

文中对2013年3月9~15日兰州持续浮尘天气过程的大气环流特征、发生机制、造成的污染状况进行了分析。结果表明：受500hPa高空冷槽东移以及地面蒙古气旋的影响,我国北方出现大范围强沙尘天气,大量沙尘随高空气流被携带至位于下游的兰州;由于兰州地处黄河河谷盆地,极易出现逆温和静风现象,不利于污染物在垂直和水平方向上的扩散,从而导致污染物在城区内的累积,形成浮尘天气,并且造成5级或以上的持续性严重污染。

The durative floating dust and pollution event over Lanzhou during March 9- 15 2013 were analyzed in this paper. It was found that by the influence of cold trough at 500 level and Mongolia cyclone,a wide range of dust event occurred in northern China and a lot of dusts were transported to downstream area Lanzhou over long distance. Temperature inversion and static wind occur frequently since Lanzhou is located in the Yellow River valley basin,and the diffusion of PM10 in the vertical and horizontal directions is inhibited. So a severe and persistent pollution of gradeⅤ or above gradeⅤ was occurred along with the floating dust in Lanzhou.