Establishment of momentum balance by form stress in a wind-driven channel
Establishment of momentum balance by form stress in a wind-driven channel
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风驱动通道中形状应力建立动量平衡
DOI：
10.1016/j.ocemod.2011.08.004
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发表时间：
2011
期刊：
影响因子：
3.2
通讯作者：
A. Hogg
中科院分区：
文献类型：
--
作者：
M. Ward;A. Hogg
我们参考南极绕极流，研究了旋转等重风驱动通道模型旋转过程中形状应力的建立。最初，力平衡类似于埃克曼层传输，其中纬向表面风由上层的科里奥利力平衡，而底层由由地形形状应力平衡的相反的经向流组成。随着经向输运的增加，等重斜率和纬向输运也增加，流动变得斜压不稳定，导致由于小规模斜压涡流而产生界面形式应力。这种形式应力改变了各层的力平衡，导致系统以地转方式重新调整到经向传输逐渐降低的新状态。这种趋势一直持续到经向输送停止并且水流仅由风和形式应力平衡为止。最终状态是由中尺度涡流场维持的多个蜿蜒射流组成的湍流。我们的结果类似于最近对南极绕极流的观测，并说明了中尺度涡流对南大洋力平衡的贡献。
We examine the establishment of form stress in the spinup of a rotating isopycnal wind-driven channel model, with reference to the Antarctic Circumpolar Current. Initially, the force balance resembles Ekman layer transport, where zonal surface winds are balanced by the Coriolis forces in the upper layers, while the bottom layers consist of an opposing meridional flow balanced by topographic form stress. As the meridional transport increases, the isopycnal slopes and zonal transport also increase and the flow becomes baroclinically unstable, leading to the development of interfacial form stresses due to small-scale baroclinic eddies. This form stress alters the force balance of the layers, causing the system to geostrophically readjust to new states with progressively lower meridional transports. This trend continues until the meridional transport stops and the current is balanced solely by winds and form stress. The final state is a turbulent flow consisting of a several meandering jets that are maintained by the mesoscale eddy field. Our results resemble recent observations of the Antarctic Circumpolar Current and illustrate the contribution of mesoscale eddies to the force balance of the Southern Ocean.