Turbulence Effects on the Formation of Cold Fog Over Complex Terrain With Large‐Eddy Simulation
Turbulence Effects on the Formation of Cold Fog Over Complex Terrain With Large‐Eddy Simulation
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DOI：
10.1029/2022gl098792
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发表时间：
2022-05
影响因子：
5.2
通讯作者：
Xin Li;Z. Pu
中科院分区：
文献类型：
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作者：
Xin Li;Z. Pu
利用嵌入在中尺度社区天气研究和预报模式中的大涡模拟（LES）研究了湍流对美国北方犹他州赫伯河谷冷雾形成的影响。LES结果表明，大尺度湍流涡旋占主导地位，并主导了行星边界层（PBL）中的混合效应。湍流混合效应、山谷流和超冷谷温度的组合导致LES模拟中的雾形成。在边界层参数化中忽略湍流涡旋导致边界层中的弱混合效应，并削弱了近地面空气冷却，因此无法在模拟中重现雾。研究表明湍流在复杂地形上雾形成中的重要作用。湍流涡旋存在于复杂地形上，可以增强混合效果，从而增强雾形成的条件。
A large eddy simulation (LES) embedded in the mesoscale community Weather Research and Forecasting model is used to examine the effects of turbulence on cold fog formation over Heber Valley in northern Utah in the U.S. The LES results indicate that large‐scale turbulent eddies prevail and dominate the mixing effects in the planetary boundary layer (PBL). The combination of turbulence mixing effects, mountain‐valley flow, and ultra‐cold valley temperature lead to fog formation in the LES simulation. The omission of the turbulent eddies in the PBL parameterization results in a weak mixing effect in the PBL and weakens the near‐surface air cooling, thus failing to reproduce the fog in the simulation. This study indicates the essential role of turbulence in fog formation over complex terrain. Turbulent eddies exist over complex terrain and can enhance mixing effects, and thus the conditions for fog formation.