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arXiv 2102.04949physics.ao-phphysics.flu-dyn
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常规中性大气边界层的通用风廓线

Universal Wind Profile for Conventionally Neutral Atmospheric Boundary Layers

Luoqin Liu, Srinidhi N. Gadde, Richard J. A. M. Stevens

摘要:

中性大气边界层(CNBLs)是自然界中常见的一种边界层,它的特征是表面电位温通量为零,并被位温的逆温所覆盖。因此,预测CNBL的风速廓线对于天气预报、气候建模和风能应用是相关的。然而,由于浮力、剪切力和科里奥利效应之间的复杂相互作用,以前预测CNBLs中速度分布的尝试取得了有限的成功。在这里,我们利用从经典的莫宁-奥布霍夫相似性理论的思想结合局部标度假设推导出的稳定性校正函数$ψ= -c_ψ(z/L)^{1/2}$的解析表达式,其中$c_ψ= 4.2$是一个经验常数,$z$是地面以上的高度,和$L$是当地的奥布霍夫长度的基础上,在该高度的位温通量,CNBLs。这个通量的解析表达式也来自使用量纲分析和摄动法的方法。我们发现,推导出的轮廓吻合得很好,在整个边界层的速度分布从高保真大涡模拟的典型CNBLs。

英文摘要:

Conventionally neutral atmospheric boundary layers (CNBLs), which are characterized with zero surface potential temperature flux and capped by an inversion of potential temperature, are frequently encountered in nature. Therefore, predicting the wind speed profiles of CNBLs is relevant for weather forecasting, climate modeling, and wind energy applications. However, previous attempts to predict the velocity profiles in CNBLs have had limited success due to the complicated interplay between buoyancy, shear, and Coriolis effects. Here, we utilize ideas from the classical Monin-Obukhov similarity theory in combination with a local scaling hypothesis to derive an analytic expression for the stability correction function $ψ= -c_ψ(z/L)^{1/2}$, where $c_ψ= 4.2$ is an empirical constant, $z$ is the height above ground, and $L$ is the local Obukhov length based on potential temperature flux at that height, for CNBLs. An analytic expression for this flux is also derived using dimensional analysis and a perturbation method approach. We find that the derived profile agrees excellently with the velocity profile in the entire boundary layer obtained from high-fidelity large eddy simulations of typical CNBLs.

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