2018年春季中国北方大范围沙尘天气对城市空气质量的影响及其天气学分析

Effectof Dust Weather on Urban Air Quality over Northern China in Spring of 2018 and its Weather Analysis

利用多源卫星数据、空气质量数据和再分析资料ERA-Interim分析了2018年春季中国北方一次沙尘天气过程中沙尘气溶胶的光学特性及垂直结构、沙尘天气对颗粒物浓度及空气质量的影响及其机制。结果表明:(1)2018年3月27-30日中国北方地区气溶胶光学厚度、吸收性气溶胶光学厚度和气溶胶指数分别大于0.4、0.035和1.0。沙尘气溶胶主要分布在地面至8 km的范围内,且体积退偏比大部分在0.06~0.4,色比0.6~1.2。(2)各城市颗粒物浓度在一定程度上均受到沙尘天气的影响。3月27-28日,PM2.5和PM10的平均值分别是国家一级标准的4.1倍和4.3倍。29-30日,PM2.5和PM10的平均值分别是国家一级标准的3.5倍和3.4倍。28日河北张家口PM10/PM2.5达4 d之最,最大比值为10.9。(3)低层贝加尔湖高压南压对内蒙古西南部及河西走廊地区的起沙有重要影响,河套地区地面气旋和低层切变是造成华北西部起沙的关键因素,鄂海地区高压脊和东北地区地面的低压系统有利于东北地区的起沙。

The optical properties and vertical distribution of dust aerosol during a dust process over northern China in spring of 2018 was analyzed using satellite data. At the same time, the impact of dust weather on the concentration of particulate matter and air quality was analyzed by using ground station data. Finally, the mechanism of dust weather on the concentration of particulate matter was analyzed by using different levels(surface, 500 hPa and 700 hPa) of geopotential height field and wind field data. The results show that:(1) The AOD, AAOD and AI were over 0.4, 0.035 and 1 in northern China from March 27 to 30, 2018, respectively. The dust aerosol was mainly distributed in the range of 8 km from the ground, and the volume depolarization ratio was mostly between 0.06 and 0.4, and the color ratio is between 0.6 and 1.2.(2) The concentration of particulate matter in each city changed due to the influence of dust weather to some extent. The average values of PM2.5 and PM10 were 4.1 times and 4.3 times of the national first-level standard from March 27 to 28. The average values of PM2.5 and PM10 were 3.5 times and 3.4 times of the national first-level standard from March 29 to 30. On the 28 th, PM10/PM2.5 reached the highest of four days in Zhangjiakou, Hebei Province, with a maximum ratio of 10.9.(3) The strengthening and southward of the Baikal high pressure at the low level was one of the most important weather systems for the dust emission in the southwestern part of Inner Mongolia and the Hexi Corridor;the surface cyclone and low-level shear in the Hetao area were the key factors for the dust emission in the western part of North China;The high-pressure ridge in the Okhotsk Sea area and the low-pressure system on the ground in the northeastern China were helpful to the dust emission in the northeast China.