Water-mass formation and potential vorticity balance in an abyssal ocean circulation
Water-mass formation and potential vorticity balance in an abyssal ocean circulation
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DOI：
10.1357/002224000321358918
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发表时间：
2000-09
影响因子：
0.5
通讯作者：
Jiayan Yang;J. Price
中科院分区：
文献类型：
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作者：
Jiayan Yang;J. Price
我们的目标是对深海环流有一些了解和直觉。要做到这一点，我们调查高度理想化的，源/汇驱动的流量计算的单层，数值海洋模型强制规定的源或汇。内部循环总是被发现是非常缓慢的和Stommel-Arons一样。另一方面，强烈的边界流可能会有很大的不同情况下，在很大程度上取决于与源或汇相关的位涡（PV）。如果源是由沿北方边界的下降流沿着施加的，则相关的PV通量为零，并且由此产生的稳定环流不会引起净摩擦扭矩。其结果是边界层流动的相当复杂的模式，包括沿北方边界的沿着强回流。如果相同的质量通量作为层流水平入流注入，则相关的PV通量是显著的，并且必须通过摩擦扭矩在稳态下平衡。其结果是一个单向的边界层流动远离源。其他实验阐明了涡旋拉伸对地形的影响。例如，在浅地形上的水平流出在盆地的边界层环流中引起净气旋摩擦力矩。因此，对稳态PV平衡的理解似乎使我们对这些深海环流中边界层流动的形式有了一些了解。
Our goal is to develop some understanding and intuition regarding abyssal ocean circulations. To do this we investigate highly idealized, source/sink-driven flows computed by a single layer, numerical ocean model forced by a prescribed source or sink. The interior circulation is always found to be very slow and Stommel-Arons like. On the other hand, the intense boundary currents may vary considerably from case to case, depending largely upon the potential vorticity (PV) associated with the source or sink. If the source is imposed by downwelling along a northern boundary, then the associated PV flux is zero, and the resulting steady circulation can induce no net frictional torque. The result is a rather complex pattern of boundary layer flow that includes a strong recirculation along the northern boundary. If the same mass flux is injected as a laminar, horizontal inflow, then the associated PV flux is significant, and must be balanced in steady state by frictional torque. The result is a unidirectional boundary layer flow away from the source. Other experiments elucidate the effect of vortex stretching on topography. For example, a horizontal outflow over shallowing topography induces a net cyclonic frictional torque in the boundary layer circulation of the basin. An understanding of the steady state PV balance thus appears to confer some insight into the form of boundary layer flows in these abyssal circulations.