Upstream effects of an Alpine-scale mountain ridge under various flow angles
Upstream effects of an Alpine-scale mountain ridge under various flow angles
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不同水流角度下阿尔卑斯山山脊的上游效应
DOI：
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发表时间：
2004
期刊：
影响因子：
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通讯作者：
G. Zängl
中科院分区：
文献类型：
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作者：
G. Zängl
本文采用数值模拟的方法，研究了不同来流角下，东西向阿尔卑斯山脉的上游效应。由于科里奥利力的影响，绕山气流在偏北气流的情况下是强烈不对称的，大部分空气被偏转到东方。当环境气流转向东时，气流分裂点也向东移动，但这种移动并不线性依赖于大尺度气流方向。地面摩擦导致分裂点向西移动，这与边界层中摩擦诱导风的转向一致。分裂点附近的力平衡表明，当忽略地面摩擦时，低层气流处于近似地转平衡状态。质量场的调整，使压力增加（减少）的山东（西）的分流点，这意味着西（东）地转风。
Numerical simulations are presented to investigate the upstream effects induced by an east-west-oriented, Alpine-scale mountain ridge under various flow angles. Due to the influence of the Coriolis force, the flow around the mountain is strongly asymmetric in the case of northerly flow, most of the air being deflected to the east. When the ambient flow turns eastward, the flow-splitting point also moves eastward, but this movement does not depend linearly on the large-scale flow direction. Surface friction induces a westward shift of the split point, which is consistent with the friction-induced wind turning in the boundary layer. The force balance in the vicinity of the split point shows that the low-level air flow is in approximate geostrophic balance when surface friction is neglected. The mass field adjusts such that the pressure increases (decreases) towards the mountain to the east (west) of the flow-splitting point, implying westerly (easterly) geostrophic wind.