Dynamics of an Abyssal Circulation Driven by Bottom-Intensified Mixing on Slopes
Dynamics of an Abyssal Circulation Driven by Bottom-Intensified Mixing on Slopes
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DOI：
10.1175/jpo-d-17-0125.1
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发表时间：
2018-06
影响因子：
3.5
通讯作者：
J. Callies;R. Ferrari
中科院分区：
文献类型：
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作者：
J. Callies;R. Ferrari
深海的大规模环流是由小规模的双密混合实现的，观测表明，这种混合在海底强烈增强，内潮汐和背风波的破裂最为剧烈。正如最近所讨论的，底部强化混合引起了一种近底部上升流和下降流的模式，这与传统上假设的广泛上升流有很大不同。这里通过考虑理想化“浴缸几何”中的行星地转动力学，探讨了深海水平环流底部强化混合的后果。正如预期的那样，上升流层和下降流层在底部斜坡上发育，并且这些层可以通过边界层理论得到很好的描述。盆地规模的环流是由流入和流出倾斜地形底部边界层的流量驱动的，这主要在内部产生纬向流和沿西部边界的净经向交换。净倾覆率由斜坡上边界层的上坡和下坡输送控制，并且可以用边界层理论来预测。
The large-scale circulation of the abyssal ocean is enabled by small-scale diapycnal mixing, which observations suggest is strongly enhanced toward the ocean bottom, where the breaking of internal tides and lee waves is most vigorous. As discussed recently, bottom-intensified mixing induces a pattern of near-bottom up- and downwelling that is quite different from the traditionally assumed widespread upwelling. Here the consequences of bottom-intensified mixing for the horizontal circulation of the abyssal ocean are explored by considering planetary geostrophic dynamics in an idealized “bathtub geometry.” Up- and downwelling layers develop on bottom slopes as expected, and these layers are well described by boundary layer theory. The basin-scale circulation is driven by flows in and out of these boundary layers at the base of the sloping topography, which creates primarily zonal currents in the interior and a net meridional exchange along western boundaries. The rate of the net overturning is controlled by the up- and downslope transports in boundary layers on slopes and can be predicted with boundary layer theory.