障碍物对风速风向影响的观测试验

随着城市化进程的加大,测站周围障碍物的存在使风观测资料失去代表性、准确性和比较性。为定量化研究障碍物对风观测的影响,开展了河北沽源构筑物观测试验,通过对比构筑物修建前后各测点的风速风向资料,分析了障碍物对风速风向的影响。分析结果显示:1障碍物对风速的衰减作用与背景风速大小有关,风速越大,衰减作用越强;2背景风速在2~6m/s时,障碍物背风面测点风速衰减随距离增大而减小,在10倍障碍物高度距离处平均约衰减15%;背景风速大于6m/s时,背风面各测点风速衰减先增大后减小,在大约5倍障碍物高度的距离处衰减最大,10倍障碍物高度的距离处平均约衰减20%~30%;3障碍物的存在使主风向的风向频率减小,对风向的影响距离为6倍障碍物高度。

Observational Experiment on Effect of Obstacles on Wind Speed and Wind Direction

With the fast urbanization of China, the existence of obstacles around the meteorological sites makes observational data lose representativeness, accuracy and comparability. In order to study how obstacles affect wind fields quantitatively, an observational experiment of a building is carried out in Guyuan, Hebei Province. The influence of obstacles on wind speed and wind direction is analyzed by comparing the wind data before and after the completion of the building. The analysis of the experiment results shows: (1) Obstacles can weaken wind speed, which is related to the background wind speed, the greater the wind speed the more obvious the attenuation. (2) While the wind velocity is between 2 m/s and 6 m/s, the wind speed attenuation of the lee sites decreases with the increasing of distance behind the obstacle, with the attenuation rate of wind speed being 15 percent or so at the distance of 10 times as long as the height of the obstacle; when the background wind velocity is more than 6 m/s, the wind speed attenuation of the lee sides weakens firstly and then strengthens, with the maximum attenuation at the distance of 5 times as long as the height of the obstacle, and the velocity attenuation by about 20 to 30 percent at the distance of 10 times as long as the height of the obstacle. (3) The frequency of prevailing wind direction decreases because of the obstacle, and the influence distance is 6 times as long as the height of the obstacle.