2014年1月济南市空气污染气象条件分析

为研究大气环流背景及气象条件对山东中西部PM2.5污染的影响，利用气象及PM2.5浓度资料，选取济南市作为典型代表城市，诊断分析了大气环流背景及气象演变过程对2014年1月济南市PM2.5浓度的影响，建立济南静稳指数公式。结果表明：2014年1月华东北部至华北南部地面至对流层中层风速均为负距平，水平方向污染扩散能力差，偏南风异常加强了南方水汽的输送，有利于气态污染物向颗粒态转化，推高了PM2.5浓度；对流层低层东亚冬季风异常偏弱，逆温增多，垂直方向污染扩散能力差；500 hPa异常高压，抑制了东亚大槽的发展，更加有利于污染物在底层的累积。天气演变过程分析表明：地面水平方向及高空垂直方向气象条件对PM2.5浓度均有影响，地面风速偏弱（偏强），高（低）湿度，风场辐合（辐散）时，PM2.5污染偏高（偏低）；边界层高度降低（升高），垂直方向气流下沉（上升），对流层中低层大气层结不稳定增强（减弱）时，PM2.5污染升高（降低）。静稳指数对于空气质量及重污染过程具有较好的预报能力。

Analysis of air pollution meteorological conditions in Jinan in January 2014

To study the influence of atmospheric circulation background and meteorological conditions on PM2.5 pollution in Midwest of Shandong Province, this paper uses meteorological and PM2.5 concentration data and selects Jinan as a typical representative city to diagnose and analyze the effect of atmospheric circulation background and meteorological evolution process on PM2.5 concentration in Jinan for the month of January 2014. The stable weather index formula of Jinan is established. Analysis shows that from the north of East China to the south of North China in January 2014, wind speed from the ground to the middle troposphere was a negative anomaly; thus, the ability of horizontal diffusion was very weak. Water vapor transportation enhanced by abnormal southerly winds helps gaseous pollutant to transform into aerosol and results in higher PM2.5 concentration. The East Asian winter monsoon is considerably weaker, with increased inversion temperature and poor vertical pollution diffusion ability. An abnormally high pressure of 500 hPa has inhibited the development of the East Asian trough and is more conducive to the accumulation of pollutants in the lower troposphere. Analysis of the weather evolution process shows that the meteorological conditions in both the horizontal direction at the ground and the vertical direction at high altitude can affect PM2.5 concentration. Results indicate that light wind, high humidity, and surface wind convergence can increase PM2.5 concentration; moreover, low depth of the planetary boundary layer, vertical airflow sinking, and increasing instability of atmospheric stratification in the middle and lower atmosphere can increase PM2.5 concentration and vice versa. A stable index can better predict air quality and heavy pollution process.