2018年春季北京一次沙尘天气边界层特征及来源分析

2018年3月27-28日，内蒙古中东部、中国东北地区、华北等地出现一次大范围沙尘天气。28日凌晨，沙尘进入北京，受此影响北京出现了严重的污染天气。本文利用中国气象局地面常规观测资料、气溶胶激光雷达、风廓线雷达资料、生态环境部大气成分等资料分析了北京沙尘天气前后边界层特征、沙尘来源以及沙尘天气前后大气污染特征。结果表明：此次沙尘天气期间，北京沙尘气溶胶退偏振比约为0.25-0.40，退偏振比数据显示此次沙尘首先从高空进入北京，比地面提前6 h。此次影响北京的沙尘主要来自于北路，东路沙尘有一定补充；沙尘影响时段，北京Ca、Fe、Na、K、Mn等元素浓度显著升高，与该物质地壳丰度相当，污染物元素Cu、Zn、Pb、Cd、As等浓度有所降低，丰度远大于该物质在地壳中丰度。

Characteristics of atmospheric boundary layer and sources of a sand-dust event during spring 2018 in Beijing

From March 27 to 28, 2018, a large-scales and-dust event occurred in central and eastern Inner Mongolia, Northeast China, and North China. In the early morning of March 28, massive dust particles arrived in Beijing, causing severe air pollution in the city. In this study, we analyzed the characteristics of the atmospheric boundary layer, the source of sand and dust, and the features of air pollution during this sandstorm event, using surface routine observation data of China Meteorological Administration, retrieved data from aerosol lidar and wind profiler radar, and atmospheric composition data from the Ministry of Ecology and Environment of the People's Republic of China. The results indicated that the depolarization ratio of dust aerosols during this dusty weather in Beijing is about 0.25-0.40. The depolarization radio data show that sand particles entered Beijing from a high altitude, about 6 h earlier than entering from the ground. These sand particles affecting Beijing mainly come from the north, and sand particles from the east have a certain supplement. During this event, the concentrations of Ca, Fe, Na, K, Mn, and other elements in Beijing increase significantly, which are equivalent to the abundance of the substance in the crust. The concentrations of pollutant elements such as Cu, Zn, Pb, Cd and As decrease, and they are much higher than the abundance of the substance in the earth's crust.