新疆风区下垫面动力学粗糙度估测值与模式定义值的对比

Aerodynamic roughness comparison between the estimated based on masts and the defined in model over Xinjiang wind areas

按风向风速标准差法估算了新疆风能资源详查区17座测风塔一定范围内的动力学粗糙度,并与期间利用的3 km和1 km分辨率的数值模式中的动力学粗糙度理论定义值进行了对比。结果表明:除了采用的landuse基数据在一些区域的错误判识而导致本研究的估测值与中、小尺度模式中的动力学粗糙度理论定义值有较大差别外,大多数比较接近,今后有必要对这些区域的landuse的分类进行客观订正;夏季强风区的动力学粗糙度估测值普遍小于中尺度模式的理论定义值;对于主、次风向上动力学粗糙度值极不均匀区域,风向与风速标准差估算法需结合使用;本研究估算的动力学粗糙度是在中性层结条件下进行的,对于中性层结条件较少发生的区域,该动力学粗糙度估算值的普适性将受到限制。

Based on the data from 17 wind masts over Xinjiang wind areas,the aerodynamic roughness lengths extending some ranges are estimated using the standard deviations of wind speed and direction.Then the estimated roughness lengths in the target areas are compared with those defined in numerical model MM5 or WRF or CALMET on account of 3 km and 1 km horizontal resolutions,respectively. Results are as follows： In most of the cases,the defined roughness lengths are moderately consistent with the estimated ones while few of them show major discrepancies due to a misinterpretation of landuse dataset.Thus further emphasis should be on modifying these datasets. The calculated roughness lengths in the strong wind areas are uniformly smaller than the defined roughness in meso-scale model in summer. To attain a better accuracy in cases where the roughness in primary and secondary wind directions is severly nonhomogeneous,the two methods of wind speed and direction standard deviations should be combined. In this study,the roughness lengths are estimated with the samples in neutral atmosphere while they will not be the applicable in areas where neutral atmosphere barely occurs.