On the effect of topographically enhanced mixing on the global ocean circulation
On the effect of topographically enhanced mixing on the global ocean circulation
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DOI：
10.1175/jpo2722.1
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发表时间：
2005-05-01
影响因子：
3.5
通讯作者：
Merryfield, WJ
中科院分区：
文献类型：
--
作者：
Saenko, OA;Merryfield, WJ
使用两个全球海洋模型实验的结果说明了粗糙地形上增强的二重混合对底水循环的强烈影响。首先，在不受剪切不稳定、对流或表面驱动混合影响的区域中，径流扩散率设置为观察到的背景水平 10(-5) m(2) s(-1)。在第二个实验中，在粗糙的底部地形上方增强了混合，以代表内潮汐的消散。获得了三个重要结果。首先，如果没有深海海洋的强化混合，北太平洋深处基本上变成一个停滞盆地，底层水环流很少，深层分层也很弱。考虑到粗糙底部地形上方的二重混合增强，会导致底部水环流和深层分层的增加，以及北太平洋中更加现实的潜在涡度分布。其次，崎岖地形上方的二重混合增强导致南极绕极流的显着增强和加深，以及南极洲周围更强的底水形成。最后，我们的实验表明，深海中内潮汐的消散和相关的增强的二重混合对于北大西洋深水形成的环流以及相关的海洋热量传输没有任何作用。
The strong influence of enhanced diapycnal mixing over rough topography on bottom-water circulation is illustrated using results from two global ocean model experiments. In the first, diapycnal diffusivity is set to the observed background level of 10(-5) m(2) s(-1) in regions not subject to shear instability, convection, or surface-driven mixing. In the second experiment, mixing is enhanced above rough bottom topography to represent the dissipation of internal tides. Three important results are obtained. First, without the enhanced mixing in the abyssal ocean, the deep North Pacific Ocean becomes essentially a stagnant basin, with little bottom-water circulation and very weak deep stratification. Allowing for the enhanced diapycnal mixing above rough bottom topography leads to increased bottom-water circulation and deep stratification and a potential vorticity distribution in the North Pacific that is much more realistic. Second, the enhanced diapycnal mixing above rough topography results in a significant intensification and deepening of the Antarctic Circumpolar Current, as well as in stronger bottom-water formation around Antarctica. Last, our experiments suggest that dissipation of internal tides and the associated enhanced diapycnal mixing in the abyssal ocean play no part in the circulation of deep water forming in the North Atlantic Ocean and in the associated transport of heat in the ocean.