On the impact of forced roll convection on vertical turbulent transport in cold air outbreaks
On the impact of forced roll convection on vertical turbulent transport in cold air outbreaks
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DOI：
10.1002/2014jd022160
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发表时间：
2014-11
期刊：
影响因子：
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通讯作者：
M. Gryschka;J. Fricke;S. Raasch
中科院分区：
文献类型：
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作者：
M. Gryschka;J. Fricke;S. Raasch
本文利用大涡模拟（LES）研究了不同冷空气爆发（CAO）情景下滚转对流对对流边界层和垂直输送的影响。对流成卷的组织是由上游表面温度的不均匀性触发的，代表冰和水。通过改变我们LES中的海冰分布，我们能够模拟每种情况下的滚动和非滚动情况。此外，通过改变不均匀性的尺度，改变滚动波长。模拟卷和云街的特性，如纵横比，辊轴的方向，和下游延伸的单辊同意密切与CAO情况下的观察。垂直湍流通量，计算每个模拟，被分解成从轧辊和无组织湍流的贡献。尽管我们的研究结果证实，辊上游非均匀性触发可以大大有助于垂直湍流通量，总通量不受辊。
We investigated the impact of roll convection on the convective boundary layer and vertical transports in different cold air outbreak (CAO) scenarios using large eddy simulations (LES). The organization of convection into rolls was triggered by upstream heterogeneities in the surface temperature, representing ice and water. By changing the sea ice distribution in our LES, we were able to simulate a roll and a nonroll case for each scenario. Furthermore, the roll wavelength was varied by changing the scale of the heterogeneity. The characteristics of the simulated rolls and cloud streets, such as aspect ratios, orientation of the roll axes, and downstream extensions of single rolls agreed closely with observations in CAO situations. The vertical turbulent fluxes, calculated for each simulation, were decomposed into contributions from rolls and from unorganized turbulence. Even though our results confirmed that rolls triggered by upstream heterogeneities can substantially contribute to vertical turbulent fluxes, the total fluxes were not affected by the rolls.