Simiu Emil, Shi Liang, Yeo DongHun
Engineering Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA.
Boundary Layer Meteorol. 2015;159(1). doi: 10.1007/s10546-015-0106-9.
Characteristics of flow in the planetary boundary layer (PBL) strongly affect the design of tall structures. PBL modelling in building codes, based as it is on empirical data from the 1960s and 1970s, differs significantly from contemporary PBL models, which account for both "neutral" flows, and "conventionally neutral" flows. PBL heights estimated in these relatively sophisticated models are typically approximately half as large as those obtained using the classical asymptotic similarity approach, and are one order of magnitude larger than those specified in North American and Japanese building codes. A simple method is proposed for estimating the friction velocity and PBL height as functions of specified surface roughness and geostrophic wind speed. Based on published results, it is tentatively determined that, even at elevations as high as 800 m above the surface, the contribution to the resultant mean flow velocity of the component normal to the surface stress is negligible and the veering angle is of the order of only 5°. This note aims to encourage dialogue between boundary-layer meteorologists and structural engineers.
行星边界层（PBL）中的气流特性对高层结构的设计有很大影响。建筑规范中的PBL建模基于20世纪60年代和70年代的经验数据，与当代PBL模型有显著差异，当代PBL模型既考虑了“中性”气流，也考虑了“传统中性”气流。在这些相对复杂的模型中估计的PBL高度通常约为使用经典渐近相似方法获得的高度的一半，并且比北美和日本建筑规范中规定的高度大一个数量级。提出了一种简单的方法来估计摩擦速度和PBL高度，它们是指定表面粗糙度和地转风速的函数。根据已发表的结果，初步确定，即使在离地面高达800米的高度，垂直于表面应力的分量对合成平均流速的贡献也可以忽略不计，并且转向角仅为5°左右。本说明旨在鼓励边界层气象学家和结构工程师之间的对话。
