济南市冬季一次典型重污染过程分析

为掌握济南市重污染天气发生规律，从而更好地为重污染天气预报预警和大气污染防治提供参考，采用空气质量监测数据、气象观测资料、雷达探测资料及轨迹模式模拟相结合的方法，对济南市2016年12月31日-2017年1月7日的持续性重污染过程，从污染演变过程、环流背景分析、气象要素特征和区域污染传输等多方面分析其形成原因及主要影响因素.结果表明:此次重污染过程期间首要污染物为颗粒物，ρ（PM₁₀）平均值为318 μg/m3，ρ（PM_2.5）平均值为200 μg/m3；地面风速在0.6~1.8 m/s范围内，风力均为1~2级，相对湿度为68%~95%，平均相对湿度为81%.在重污染过程中，从地面至800 m左右高度始终维持较强逆温层，逆温频次高达91.1%，污染边界层高度较低，大部分时间都在500 m以下.采用情景模拟分析方法计算得到，区域输送对济南市PM_2.5的贡献率为20%~35%.研究显示:此次重污染过程是在区域性污染背景下由本地不利的扩散条件造成的，静稳大气形势提供有利的环流背景，平流雾、辐射雾交替产生，持续性的高湿加重了污染程度；近地面的静风、高湿，垂直方向的双逆温层甚至多逆温层的结构是影响此次重污染过程的重要气象要素；区域性污染传输对此次重污染天气的发展有显著贡献，污染初期主要来自河北省中南部的输送，随着污染加重，有来自偏南、偏东方向的局地气团输送. 

Analysis of a Typical Heavy Pollution Event in Winter in Jinan City

In order to understand the factors governing heavy pollution weather in Jinan, the characteristics and formation mechanism of a continuous heavy air pollution event from December 31st 2016 to January 7th 2017 were investigated from the aspects of pollution evolution, atmospheric environmental background, the features of meteorological factors, and regional transport using environmental data, observed weather data, the radar-detected data and the HYSPLIT model. The results indicated that the primary pollutant during this heavy pollution event was particulate matter, and the average values of ρ(PM₁₀) and ρ(PM_2.5) were 318 and 200 μg/m3, respectively. The ground wind speed was within the range of 0.6-1.8 m/s, with the relative humidity ranging from 68% to 95%, and the average relative humidity was 81%. In this event, a strong inversion layer was maintained from the ground to a height of around 800 m, with inversion frequency as high as 91.1%. By using the scenario simulation analysis method, the contribution rate of regional transportation to PM_2.5 in Jinan was determined to be 20%-35%. The research showed that this event was caused by local unfavorable diffusion conditions under the regional pollution background. The stable atmospheric circulation pattern provided a favorable environmental field, and advection-radiation fogs increased the pollution level. Low wind speed, high humidity in the horizontal direction, and a temperature inversion structure in the vertical direction were the most important impact factors in this heavy air pollution incident. Regional pollutants transport made a significant contribution to this event. In the initial stage, the pollution mainly came from the transportation in central and southern Hebei; with the aggravation of pollution, there was local air mass transportation from south to east.