利用风廓线雷达资料对北京地区边界层日变化特征的分析研究

Analysis of Daily Variation Characteristics of Boundary Layer in Beijing Area by Wind Profile Radar Data

利用2015年全年AQI和风廓线雷达资料,对北京地区严重污染天气条件下的边界层日变化特征进行分析。结论表明:(1)严重污染天气水平风速很小,尤其在近地面风速接近0 m/s,全天垂直风速分布平均,各层过渡平缓,边界层非常稳定,几乎没有起伏。(2)高浓度污染物的存在阻挡了太阳辐射对地面的传输,同时地表的长波辐射也难以向上扩散,积累到一定程度才会向上发展。缺少热动力使得边界层更加稳定,不利于污染物扩散,形成稳定边界层利于污染天气维持。这一过程形成了污染物与稳定边界层互相促进的恶性循环。(3)风场的动力作用不足,热力湍流起主导作用,湍流强度相比晴空天气要小很多。

Based on the data of AQI and wind profiler for the whole year of 2015, the daily variation characteristics of boundary layer under severe polluted weather conditions in Beijing were analyzed. The results show that： （1） Wind speed is very small at severe pollution weather, especially near-surface wind speed is nearly 0 m/s. Vertical wind velocity is evenly distributed. Layer is gentle and boundary layer is stable and almost undulating. （2） The existence of high concentrations of pollutants blocked the transmission of solar radiation on the ground, while the surface of the long-wave radiatiofi is difficult to spread, it will be accumulated to the development when upward to a certain extent. The lack of thermal power makes the boundary layer more stable. The stable boundary layer is not conducive to the spread of pollutants, and the formation of a stable boundary layer is conducive to pollution weather maintenance. This process forms a vicious circle of mutual promotion between pollutants and stable boundary layers. （3） The dynamical effect of the wind field is insufficient, the thermal turbulence plays the leading role, and the turbulence intensity is much smaller than that of the clear sky.