【摘要】 利用北京、天津、河北地区常规气象数据、PM_2.5浓度、激光雷达数据,铁塔数据,结合风廓线数据对2015年10月13¹7日发生在北京的空气重污染过程中大气热力和动力结构进行分析.结果表明,白天热力条件转好后,边界层低层垂直方向气流由上-下运动转变为倾斜运动,同时水平方向偏南风增大,高浓度气团向北京移动,污染物输送增强,造成这种空间结构的原因主要是热力条件加强后等温面由准东-西向转变为西北-东南向,由于山地加热激发的重力波振幅在白天增强,高空水平方向输送至北京的污染物在垂直方向出现向上和向下的传输.16日白天地面PM_2.5浓度的快速升高,这是在PM_2.5存在一定垂直交换的情况下,近地面偏南风输送的作用所致,以上出现的大气污染物输送和扩散机制可以在一定程度上解释区域重污染背景下,白天混合层高度升高而近地层PM_2.5浓度却随之升高的现象.更多还原

【Abstract】 Based on the conventional meteorological data, PM_2.5 concentration, lidar data, tower data combined with wind profile data on 13¹7 October 2015 in Beijing, Tianjin and Hebei, thermal and dynamic structure of heavy air pollution process have been researched. The results showed that the thermal conditions turn better during the day, vertical direction in the lower boundary layer changes from top-down motion into tilting motion, while southerly winds strengthened, pollution was transported enhanced, the main reasons for this spatial structure was that quasi east-west isotherm changed into the northwest-southeast direction after the thermal conditions strengthened and gravity wave caused by mountain heating excited amplitude increased during the day, resulted in air pollutants transmitted to Beijing at high-altitude appeared up and down transmission in the vertical direction, PM_2.5 concentration increased rapidly, there was vertical exchange under the condition of near ground southerly transports on November 16th, above transport and dispersion mechanism may explain the phenomenon, which mixing height increased with an increased PM_2.5 concentration in the daytime under the background of region heavy pollution.更多还原