中文摘要：

利用2007年4月17日—2008年4月16日兰州大学半干旱气候与环境观测站边界层气象塔的风速、风向、温度、气压、湿度等观测资料,采用经典的廓线法和风速、风向标准差法,分别计算了中性大气层结下观测站下垫面粗糙度长度,并得到了具有黄土高原地理特征的地表粗糙度及其时空变化特征。计算结果表明,季节变化对粗糙度的影响幅度可达0.159 m,空间非均一性对粗糙度的影响幅度可达0.155 m。测站附近粗糙度春季为0.017 m,夏季为0.062 m,秋季为0.065 m,冬季为0.018m。测站西北方向上游粗糙度春季为0.17 m,夏季为0.22 m,秋季为0.34 m,冬季为0.05 m。测站东南方向上游粗糙度春季为0.11 m,夏季为0.17 m,秋季为0.19 m,冬季为0.05 m。该站下垫面粗糙度计算宜选用风速为6±1.5 m·s^-1,风向变化30°范围内的数据。

英文摘要：

Using the observational data from semi-arid climate and environment observatory of Lanzhou University meteorological observation tower which contained wind speed, wind direction, temperature, pressure, humidity data from April 17, 2007 to April 16, 2008. The surface roughness length at the observation station in the neutral atmosphere condition was calculated with classic wind profile and wind speed standard deviation methods, meanwhile, the data analysis obtained the spatial and temporal features of the surface roughness length in Loess Plateau geographical environment. The results show that the impact of seasonal variation on the roughness length can rate up to 0. 159 m and the impact of heterogeneous underlying surface on the roughness length can rate up to 0. 155 m. The surface roughness length near the observation station is： 0. 017 in spring, 0. 662 m in summer, 0. 065 in autumnm and 0. 018 m in winter. The roughness of northwest direction at station reaches 0.17 m in spring, 0.22 m in summer, 0.34 m in autumn and 0.05 m in winter. The roughness of southeast direction at observation station reaches 0.11 m in spring, 0.17 m in summer, 0. 19 m in autumn and 0.05 m in winter. The best selection of data for roughness calculation is wind speed 6± 1. 5 m · s^-1 and the wind direction changes within 30° in this station.