The Interaction of Katabatic Flow and Mountain Waves. Part II: Case Study Analysis and Conceptual Model
The Interaction of Katabatic Flow and Mountain Waves. Part II: Case Study Analysis and Conceptual Model
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下降流和山波的相互作用。
DOI：
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发表时间：
2007
期刊：
影响因子：
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通讯作者：
R. Pielke
中科院分区：
文献类型：
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作者：
G. Poulos;J. Bossert;T. Mckee;R. Pielke
通过对1993年9月初一个个例夜的详细模拟的数值分析，作者发展了一个关于夜间边界层下降气流与山波相互作用的概念模式（MKI）。一个配套文件（第一部分）描述了天气和中尺度观测的情况下，从复杂地形（阿斯科特）实验和理想化的数值模拟，表现出组件的概念模型MKI在这里。读者也可以参考第一部分，了解详细的科学背景和动机。这些现象的相互作用是复杂且非线性的，因为越过屏障的流动所形成的山波系统的振幅、波长和垂直结构的部分形态归因于排水流发展的不断变化的大气稳定性。同时，下降流受到地形引起的重力波演化的影响，这可能包括显著改变波长、振幅、流量大小和波破碎行为。除了湍流（包括冲刷）引起的影响外，在距离地面下折流层物理距离的高度处，背风面重力波结构的扰动可通过大气柱的传输反映在下折流中。模拟结果表明，高空大气结构的演变可以在控制下降流的地面压力梯度力中产生局部变化。可变性被发现发生在两个尺度上，在中-由于山波系统的演变的顺序为一个小时，和在微尺度上，由于快速波的演变（短波长）和波破碎引起的波动。有人建议，MKI机制解释了一部分的下降流观测记录的变异。
Via numerical analysis of detailed simulations of an early September 1993 case night, the authors develop a conceptual model of the interaction of katabatic flow in the nocturnal boundary layer with mountain waves (MKI). A companion paper (Part I) describes the synoptic and mesoscale observations of the case night from the Atmospheric Studies in Complex Terrain (ASCOT) experiment and idealized numerical simulations that manifest components of the conceptual model of MKI presented herein. The reader is also referred to Part I for detailed scientific background and motivation. The interaction of these phenomena is complicated and nonlinear since the amplitude, wavelength, and vertical structure of the mountain-wave system developed by flow over the barrier owes some portion of its morphology to the evolving atmospheric stability in which the drainage flows develop. Simultaneously, katabatic flows are impacted by the topographically induced gravity wave evolution, which may include significantly changing wavelength, amplitude, flow magnitude, and wave breaking behavior. In addition to effects caused by turbulence (including scouring), perturbations to the leeside gravity wave structure at altitudes physically distant from the surface-based katabatic flow layer can be reflected in the katabatic flow by transmission through the atmospheric column. The simulations show that the evolution of atmospheric structure aloft can create local variability in the surface pressure gradient force governing katabatic flow. Variability is found to occur on two scales, on the meso- due to evolution of the mountain-wave system on the order of one hour, and on the microscale due to rapid wave evolution (short wavelength) and wave breaking–induced fluctuations. It is proposed that the MKI mechanism explains a portion of the variability in observational records of katabatic flow.