On the boundary‐layer structure over highly complex terrain: Key findings from MAP
On the boundary‐layer structure over highly complex terrain: Key findings from MAP
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DOI：
10.1002/qj.71
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发表时间：
2007-04
影响因子：
8.9
通讯作者：
M. Rotach;D. Zardi
中科院分区：
文献类型：
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作者：
M. Rotach;D. Zardi
在 MAP 中，科学项目之一致力于“复杂地形中的边界层”。在许多子项目中，边界层问题得到了解决，详细的高分辨率多传感器观测与模型模拟相结合，允许对湍流过程进行充分的参数化。在本文中，简要介绍了这些项目，并试图总结其主要发现并将其纳入共同的视角。发现空间变异性很大，但与地形严格相关，因此允许可能的参数化。传统的边界层缩放方法不能简单地应用于高度复杂的地形，但 MAP 的一些发现表明，这些缩放关系有可能适当扩展，以覆盖复杂地形的各种情况。发现狭窄山谷中的平均边界层结构和热驱动流与其他地方较大山谷的先前结果大体上不一致。此外，据报道，当地环流对山谷和自由对流层之间的交换有很大贡献。特别是，它们对低层大气的影响范围似乎比行星边界层内的湍流传输所暗示的要大。因此，在地形未解析的较大规模数值模型中，用于局部交换的可能的子网格参数化似乎是合理的。版权所有 © 2007 英国皇家气象学会
Within MAP, one of the scientific projects was devoted to ‘Boundary Layers in Complex Terrain’. In a number of subprojects, boundary‐layer issues were addressed and detailed high‐resolution multi‐sensor observations were combined with simulation by models allowing for adequate parametrization of turbulence processes. In this contribution, the projects are briefly introduced and an attempt is made to summarize their key findings and to put them into a joint perspective. Spatial variability is found to be large but strictly related to topography and therefore allowing for possible parametrization. Traditional boundary‐layer scaling approaches cannot simply be applied over highly complex topography, but some of the MAP findings suggest the potential for suitable extensions of those scaling relations to cover various cases of complex terrain. The mean boundary‐layer structure and thermally driven flows in narrow valleys are found not to be generally in line with previous results from larger valleys elsewhere. Furthermore, local circulations are reported to contribute considerably to exchange between valley and free troposphere. In particular, the range of their effects on the lower atmosphere seems to be larger than just turbulent transport within the planetary boundary layer would suggest. Thus in larger‐scale numerical models where the topography is not resolved, possible sub‐grid parametrizations for local exchange seem to be in order. Copyright © 2007 Royal Meteorological Society