We review developments in the field of boundary-layer flow over complex topography, focussing on the period from 1970 to the present day. The review follows two parallel strands: the impact of hills on flow in the atmospheric boundary layer and gravity-driven flows on hill slopes initiated by heating or cooling of the surface. For each strand we consider the understanding that has resulted from analytic theory before moving to more realistic numerical computation, initially using turbulence closure models and, more recently, eddy-resolving schemes. Next we review the field experiments and the physical models that have contributed to present understanding in both strands. For the period 1970–2000 with hindsight we can link major advances in theory and modelling to the key papers that announced them, but for the last two decades we have cast the net wider to ensure that we have not missed steps that eventually will be seen as critical. Two important new themes are given prominence in the 2000–2020 period. The first is flow over hills covered with tall plant canopies. The presence of a canopy changes the flow in important ways both when the flow is nearly neutral and also when it is stably stratified, forming a link between our two main strands. The second is the use of eddy-resolving models as vehicles to bring together hill flows and gravity-driven flows in a unified description of complex terrain meteorology.

中文翻译：

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复杂地形上的边界层流

我们回顾了复杂地形上边界层流领域的发展，重点是从 1970 年至今。审查遵循两条平行线：山丘对大气边界层中流动的影响，以及由地表加热或冷却引起的山坡上的重力驱动流动。对于每条链，在转向更现实的数值计算之前，我们考虑了从解析理论得出的理解，最初使用湍流闭合模型，最近使用涡旋解析方案。接下来，我们回顾了有助于理解这两个方面的现场实验和物理模型。在 1970 年至 2000 年期间，事后看来，我们可以将理论和建模方面的重大进展与宣布这些进展的关键论文联系起来，但在过去的二十年里，我们撒了大网，以确保我们不会错过最终将被视为至关重要的步骤。在 2000 年至 2020 年期间，两个重要的新主题变得突出。第一个是流过覆盖着高大植物树冠的山丘。当水流接近中性和稳定分层时，树冠的存在会以重要的方式改变水流，在我们的两条主干线之间形成联系。二是使用涡旋解析模型作为载体，将山地流和重力驱动流结合在一起，统一描述复杂地形气象学。当水流接近中性和稳定分层时，树冠的存在会以重要的方式改变水流，在我们的两条主干线之间形成联系。二是使用涡旋解析模型作为载体，将山地流和重力驱动流结合在一起，统一描述复杂地形气象学。当水流接近中性和稳定分层时，树冠的存在会以重要的方式改变水流，在我们的两条主干线之间形成联系。二是使用涡旋解析模型作为载体，将山地流和重力驱动流结合在一起，统一描述复杂地形气象学。