Derivation of Structure Parameters of Temperature and Humidity in the Convective Boundary Layer from Large-Eddy Simulations and Implications for the Interpretation of Scintillometer Observations
Derivation of Structure Parameters of Temperature and Humidity in the Convective Boundary Layer from Large-Eddy Simulations and Implications for the Interpretation of Scintillometer Observations
复制标题
从大涡模拟推导对流边界层温度和湿度的结构参数及其对闪烁仪观测解释的意义
DOI：
10.1007/s10546-013-9801-6
复制
发表时间：
2013
影响因子：
4.3
通讯作者：
B. Gioli
中科院分区：
文献类型：
--
作者：
B. Maronga;A. Moene;D. Dinther;S. Raasch;F. Bosveld;B. Gioli
本文利用高分辨率大涡模拟方法（LES）对一个对流边界层进行了数值模拟，得到了温度C_{T}^2 $$和湿度C_q ^2 $$的湍流结构参数。边界条件和模式强迫来自荷兰Cabauw的测量。研究了从大涡模拟中获取结构参数的三种不同方法。这三种方法得到的结构参数垂直剖面形状与以往的实验和LES结果吻合较好。根据该方法，偏差的幅度高达一个因素的两个被发现和追溯到离散化和数值耗散的平流方案的影响。此外，我们验证LES数据与机载和大孔径雷达（LAS）测量Cabauw。利用虚路径测量研究了混合层和近地面层C_{T}^2$$的变化及其对机载和LAS测量的影响。在LES数据中，沿给定水平路径的高变率C_{T}^2沿着与羽流（高值）和下降气流（低值）有关。由于路径长度有限，$$C_{T}^2$$的路径平均值随时间迅速变化。LES的结果表明，测量的路径平均值需要足够的时间平均和适当的路径长度与地面以上的高度的LAS的比例，以接近域平均值$$C_{T}^2 $$。
We derive the turbulent structure parameters of temperature $$C_{T}^2$$ and humidity $$C_q^2$$ from high-resolution large-eddy simulations (LES) of a homogeneously-heated convective boundary layer. Boundary conditions and model forcing were derived from measurements at Cabauw in The Netherlands. Three different methods to obtain the structure-parameters from LES are investigated. The shape of the vertical structure-parameter profiles from all three methods compare well with former experimental and LES results. Depending on the method, deviations in the magnitude up to a factor of two are found and traced back to the effects of discretization and numerical dissipation of the advection scheme. Furthermore, we validate the LES data with airborne and large-aperture scintillometer (LAS) measurements at Cabauw. Virtual path measurements are used to study the variability of $$C_{T}^2$$ in the mixed layer and surface layer and its implications for airborne and LAS measurements. A high variability of $$C_{T}^2$$ along a given horizontal path in the LES data is associated with plumes (high values) and downdrafts (low values). The path average of $$C_{T}^2$$ varies rapidly in time due to the limited path length. The LES results suggest that measured path averages require sufficient temporal averaging and an adequate ratio of path length to height above the ground for the LAS in order to approach the domain average of $$C_{T}^2$$.