指数律参数选取对指数和廓线精度的影响

基于广州市主城区水平比例尺为1:7 000和垂直比例尺分别为1:500、1:1 000、1:2 000的三维建筑模型，在B类边界层中性流条件下进行风洞模拟. 利用26个测点、15个高度的西北和东南两种盛行风况下的风速数据，分析指数律参考高度zref、零平面位移d、采样厚度t等3个参数对指数α和拟合精度的不确定性影响，并为指数律应用中精度的提高提供了相应的建议. 实验结果表明:参考测点最高高度α的均值和离散度相对较小，且拟合较为理想；d的引入能提高拟合精度，且与α呈负相关；不考虑零平面位移d的指数律尤其对下垫面非均质、测点众多的研究更为实际；不同粗糙程度的下垫面，α在0.25-1H廓线厚度段内收敛，是理想的采样厚度.

The influence of exponential parameters selection on the exponent and profiles precision

Based on the 3D model of Guangzhou main built-up area at 1:7000 horizontal scale, 1:500,1:1000,1:2000 vertical scale respectively, a wind tunnel simulation is carried out on the neutral flow of B atmospheric boundary layer. With wind velocities in more than 26 test points,15 heights of each prevailed wind of the northwest and southeast, the uncertainties generated by reference height zref, zero-plane displacement height d and sample thickness t to exponent α and fitting precision are all discussed, which provide some guidance to raise fitting precision on power law applications later. It is founded that a reference height equal to maximum height of test points has a relatively smaller mean value and dispersion of α, and a better fitting precision than other zref ;d can improve fitting precision and is correlated with α negatively. The exponential law of d in the zero plane displacement is not considered; it is more practical especially for the researches of inhomogeneous terrain and numerous test points. In differently rough terrain, α converges at 0.25-1H of the thickness of wind profiles and 0.25-1H is the ideal sampling thickness.