Stratification and mixing on sloping boundaries
Stratification and mixing on sloping boundaries
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DOI：
10.1029/2008gl034607
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发表时间：
2008-07-30
影响因子：
5.2
通讯作者：
Mohrholz, V.
中科院分区：
文献类型：
--
作者：
Lorke, A.;Umlauf, L.;Mohrholz, V.
在湖泊和海洋中，垂直输运在很大程度上受沿各自盆地边界的局部混合沿着控制。直接测量的湍流混合和密度分层在底部边界层的一个大而深的湖泊揭示了跨斜坡平流附近的倾斜边界的重要性，为当地和流域尺度的垂直运输。周期性的，内部的波驱动，发生向上和向下倾斜的定向电流的结果在周期性加热和冷却的边界层。冷却的边界层期间的上坡流与不稳定的分层和湍流扩散率超过期间观察到的下坡流几乎一个数量级。该层中的水与来自盆地内部的水的周期性替换保持垂直密度梯度，从而提高边界混合的总体效率。
In lakes as well as in the ocean vertical transport is, to a large extent, controlled by localized mixing along the boundaries of the respective basin. Direct measurements of turbulent mixing and density stratification in the bottom-boundary layer of a large and deep lake reveal the importance of cross-slope advection near sloping boundaries for local and basin-scale vertical transport. The periodic, internal wave driven, occurrence of up- and downslope directed currents results in periodic heating and cooling of the boundary layer. Cooling of the boundary layer during periods of up-slope flow is associated with unstable stratification and turbulent diffusivities exceed those observed during periods of down-slope flow by almost one order of magnitude. The periodic replacement of water in this layer with water from the interior of the basin maintains vertical density gradients and thus enhances the overall efficiency of the boundary mixing.