山区林地粗糙度的推求

Calculation of Roughness Parameters over Forest in a Hilly Region

应用实测资料计算复杂地面森林冠层的动量、潜热和粗糙参数以及动量总体输送系数(CM)、热量总体输送系数(CH)和水汽总体输送系数(CE)的参数。使用最大相关法计算本地风的粗糙度Z0M与零通量面d0M,同样结果较满意。在假设θS=θRAD的情况下计算水汽粗糙度Z0H,表明斯坦顿系数St-1=ln(Z0M/Z0H)/K比过去的调查结果大。温度的零通量计算结果为d0H=(11.9),该值与d0M值(=12.8)相近。通过修改后方程计算表面湿度参数α,表面湿度参数α的值为0.61,该值与冠层的相对湿度相近。因此α的值可以用冠层顶部的相对湿度来计算。计算森林区粗糙度的方法和模型可推广应用到黑河流域。

Applying actually measured data we have calculated the bulk parameterization of momentum, apparent and latent heat fluxes, roughness as well as the related bulk transfer coefficients, CM, CH and CE in a hilly region with vegetation. In the study, the relative surface temperature and relative humidity profiles with canopy were also measured. By use of the maximum correlation method, the roughness length and zero-plane displacement for wind, Z0M and d0M, were determined. The roughness length for water vapor （Z0H） was evaluated by sassuming that θS=θRAD. The result indicates that the Stanton number, S^-1 t=ln（Z0M/Z0H）/K, shows larger value as compared with past in- vestigations. And zero-plane displacement for temperature d0H （= 11.9） was almost same value as d0M （= 12. 8）. Base on the modified bulk formulation by use of the surface wetness parameter a, the value a was evaluated as 0. 61, which agreed well with the relative humidity, near the canopy top. This calculation method and model could be applied in the Heihe river basin.