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临山城市夜间山风可影响污染物的分布,但夜间低层山风的演变及其对污染物分布的影响观测研究较少。本文通过325 m气象塔及一台测风激光雷达快速移动到四地的定点观测,获取了北京城区一次三维夜间山风及污染物分布特征,为城市测风提供了一种新方法。结果表明:相距20 km南、北城均有低层风向切变且间隔为1.5 h;城北低空急流的高度及风速均大于城东南;240 m和地面颗粒物的水平分布一致;PM2.5地面高值区的南移时间与北风急流到达时间一致,晚于地面风转向时间。
Night mountain winds in Linshan City can affect the distribution of pollutants, but there are few observational studies on the evolution of low mountain breeze at night and their impact on the distribution of pollutants. In this paper, a three-dimensional night-time mountain wind and pollutant distribution in Beijing urban area are obtained through the fixed-point observation of 325 m meteorological tower and a wind-lidar moving rapidly to four places, providing a new method for urban wind measurement. The results show that the low-level wind shear is 1.5 h apart and the interval is 1.5 h in the north and 20 km apart. The height and wind speed of the low-level jet stream in the north of the city are greater than those in the southeast of the city. The horizontal distribution of 240 m and the ground- The time of the southward move is the same as that of the north wind jet, which is later than the time of the windward turn.