Structure of the PBL
Structure of the PBL
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DOI：
10.1007/978-1-935704-16-4_2
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发表时间：
1988
期刊：
影响因子：
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通讯作者：
J. Wyngaard
中科院分区：
文献类型：
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作者：
J. Wyngaard
即使是最漫不经心的观察者也会注意到风的变化。虽然它在时间上有一定的持久性，但它的漩涡和漩涡的细节似乎是无限可变的。随着天气系统的演变，它的强度每天都在变化，随着太阳的升起和落下，它的强度每天都在变化。它受到地形特征和城市建筑的强烈调制。我们如何能描述如此复杂的现象呢？当然，答案是，尽管风的波动是随机的，但它的行为即使是微小的细节也不是没有规律的。我们相信它满足纳维-斯托克斯方程，100多年来，我们一直使用该方程，结合测量，研究低层大气中风的行为。虽然它的瞬时，局部细节基本上是不可预测的，因为任何人都可以看到不断变化的，从烟囱蜿蜒的羽流可能会得出结论，我们确实了解平均风的行为-它依赖于稳定性，距离地面的距离，平均天气条件，至少在简单的地形。我们也非常了解它的动荡起伏。今天，我们可以估计”最可能”的行为，在许多重要的湍流弥散问题的行星边界层（PBL），尽管混乱的实际过程。我将概述一些知识的PBL和它的湍流，使我们能够成功地处理应用，如色散。这些知识主要依赖于观察，但在解释这些观察并从中构建有用的概念模型时，仍有很大的个性化空间。因此，本章的解释和说明在一定程度上反映了我自己对PBL的看法。我将集中讨论
Even the most casual observer notices the changes in the wind. Though it has a certain persistence in time, the details of its swirls and eddies seem infinitely variable. Its strength changes day to day as weather systems evolve, and day to night as the sun rises and sets. It is modulated strongly by terrain features and by urban architecture. How can we hope to describe such a complicated phenomenon? The answer, of course, is that even though the wind fluctuates randomly, its behavior-even in its minuscule details-is not without order. We believe that it satisfies the Navier-Stokes equation, and for over 100 years we have used that equation, in conjunction with measurements, to study the behavior of the wind in the lower atmosphere. Although its instantaneous, local details are essentially unpredictable, as anyone who watches the continuously changing, meandering plume from a smokestack might conclude, we do understand the behavior of the average wind-its dependence on stability, distance from the surface, mean weather conditions, and the likeat least in uncomplicated terrain. We also understand much about its turbulent fluctuations. Today we can estimate the" most likely" behavior in many important turbulent dispersion problems in the planetary boundary layer (PBL), in spite of the chaos of the actual process.I shall outline some of the knowledge about the PBL and its turbulence that allows us to deal successfully with applications such as dispersion. This knowledge rests principally on observations, but there is room for a good deal of individuality in interpreting these observations and fabricating useful conceptual models from them. Thus, the interpretations and explanations in this chapter reflect to some extent my own way of viewing the PBL. I shall concentrate on