A study on new turbulence parameterization with utilization of numerical and wind-tunnel experiments

用数值模式再现大气边界层中的湍流输送，一个合适的参数化湍流运动公式是绝对必要的。为了改进大涡模拟（LES）和雷诺平均数值模拟（RANS）中使用的湍流参数化方案，进行了以下研究。首先，我们进行了一组数值模拟的基础上LES在一个中等稳定的边界层，并试图评估的误差的垂直通量的自洽性，根据Germano身份。其次，为了解决Mellor-Yamada-Nakanishi-Niino（MYNN）模型的问题，我们试图修改稳定分层情况下的温度-压力相关的弛豫时间尺度。与原MYNN模型相比，修正后的模型没有临界Richardson数，并且湍流运动的影响仍然适用于2级模型中的所有Richardson数值。最后，我们进行了数值和风洞实验，以确定通量理查森数对大气静态稳定度的依赖。这些结果表明，通量Richardson数可以超过1。

An appropriate formulation of parameterized turbulent motions is absolutely essential for reproducing turbulent transfer in the atmospheric boundary layer with a numerical model. The following studies are conducted in order to improve turbulence parameterization schemes used in the Large-Eddy Simulation (LES) and the Reynolds Averaged Numerical Simulation (RANS). First, we perform a set of numerical simulations based on the LES in a moderately stable boundary layer and attempt to evaluate the error of the vertical flux in terms of self-consistency, based on the Germano identity. Second, to solve problems with the Mellor-Yamada-Nakanishi-Niino (MYNN) model, we attempted to modify a relaxation time scale of temperature-pressure correlation for the stable stratification case. In contrast to the original MYNN model, the modified model has no critical Richardson number, and the effect of turbulent motions remains for all Richardson number values in the level 2 model. Lastly, we perform numerical and wind-tunnel experiments to identify dependence of flux Richardson number on atmospheric static stability. These results indicate that flux Richardson number can be over unity.