Bridging the Urban Canopy Sublayer to Aerodynamic Parameters of the Atmospheric Surface Layer
Bridging the Urban Canopy Sublayer to Aerodynamic Parameters of the Atmospheric Surface Layer
复制标题
将城市冠层子层与大气表面层的空气动力学参数联系起来
DOI：
10.1007/s10546-022-00723-8
复制
发表时间：
2022
期刊：
影响因子：
--
通讯作者：
Katul, Gabriel
中科院分区：
文献类型：
--
作者：
Li, Qi;Katul, Gabriel
在均匀分布的长方体组成的密集城市冠层粗糙度亚层中，时间和平均速度剖面呈近似指数型，衰减系数与深度无关。利用背景平均水平压力梯度、总应力垂直梯度和阻力之间的一维动量平衡，提出了一个与零平面位移和气动粗糙度长度相联系的公式。然后利用独立变化长方体的平面（）和正面（）密度的大涡模拟（LESs）来探索城市RSL内部的色散效应。通过对冠层上方的平均速度拟合测井剖面，利用LES结果进行计算。在冠层内，LES结果也用于估计(i)拟合计算时间和平面平均速度的指数曲线，（ii）阻力系数曲线，以及（iii）湍流和弥散应力。LES结果表明，色散应力与湍流应力大小相当，且作用方向相同。此外，由色散应力垂直梯度决定的色散输运约占湍流应力梯度的25-75%。这些分散效应通过两种机制影响（和千）：(i)减少有效调整长度尺度，导致增加；（ii）增加有效混合长度，导致在大范围内减少。这两种效应被证明是部分补偿的，引起了冠层内部高度的明显常数。讨论了平均再循环的影响和阻力质心法的应用。分析还评估了在冠层之上延伸的有限粗糙度子层厚度对导出表达式的影响。
Within the roughness sublayer (RSL) of dense urban canopies composed of uniformly distributed cuboids, the time and planar-averaged mean velocity profile exhibits an approximate exponential shape characterized by a depth-independent attenuation coefficienta. A formulation that linksato the zero-plane displacementdand aerodynamic roughness lengthis proposed using a one-dimensional momentum balance between the background mean horizontal pressure gradient, vertical gradients of total stresses, and the drag force. Dispersive effects onawithin the urban RSL are then explored using large-eddy simulations (LESs) that vary independently the planar () and frontal () densities of the cuboids. The LES results are used to computedandby fitting a log-profile to the mean velocity above the canopy. Within the canopy, the LES results are also used to estimate (i)aby fitting an exponential profile to the computed time and planar-averaged velocity, (ii) profiles of drag coefficients, and (iii) turbulent as well as dispersive stresses. The LES results demonstrate that dispersive stresses can be commensurate with turbulent stresses in magnitude and act in the same direction. Moreover, dispersive transport, determined from vertical gradients of dispersive stresses, is some 25–75% of turbulent stress gradients. These dispersive effects impacta(and thusdand) via two mechanisms: (i) reducing the effective adjustment length scale that leads to an increase inaand (ii) increasing the effective mixing length that leads to a reduction inaacross a wide range ofand. These two effects are shown to be partly compensatory giving rise to an apparent constantawith respect to height inside the canopy. The effects of mean recirculation and the usage of the drag force centroid method to estimatedare discussed. The analysis also evaluates the consequences of a finite roughness sublayer thickness extending above the canopy on the derived expressions.
登录
查看更多内容
影响因子：
4.3
作者：
Giometto, M. G.;Christen, A.;Parlange, M. B.
通讯作者：
Parlange, M. B.
影响因子：
3.7
作者：
RAUPACH, MR
通讯作者：
RAUPACH, MR
DOI：
10.1029/2020jd033812
发表时间：
2021-02
期刊：
Journal of Geophysical Research: Atmospheres
影响因子：
--
作者：
Qi Li;Jiachuan Yang;Long Yang
通讯作者：
Qi Li;Jiachuan Yang;Long Yang
影响因子：
4.3
作者：
Christen, Andreas;Rotach, Mathias W.;Vogt, Roland
通讯作者：
Vogt, Roland
影响因子：
4.3
作者：
R. Moriwaki;M. Kanda
通讯作者：
R. Moriwaki;M. Kanda