Wind‐driven circulation in one‐ and two‐layer oceans of variable depth
Wind‐driven circulation in one‐ and two‐layer oceans of variable depth
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不同深度的单层和双层海洋中的风驱动环流
DOI：
10.1111/j.2153-3490.1968.tb00347.x
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发表时间：
1968
期刊：
影响因子：
2
通讯作者：
P. Welander
中科院分区：
文献类型：
--
作者：
P. Welander
利用埃克曼型动力学研究了均匀两层海洋底部地形的影响。在摩擦力仅在横向边界处很重要的情况下，可以获得显式解。定性地讨论了内部摩擦力也变得重要的情况。均质海洋和双层海洋的解之间存在本质区别。在均质海洋中，当 ?/?y(f/H) 分别为正值和负值时（f 为科里奥利参数，H 为深度，y 为北向坐标），会出现西边界流或东边界流，并存在受海底地形影响的斯维尔德鲁普型内环流。这种情况之前已在文献中讨论过。在两层模型中，上层比下层薄，下层的运动变小。上层解类似于 Stommel (1948) 给出的具有西边界电流的单层解，由于界面的有限变形而进行了一些修改。下层也有西边界流。如果 ?/?y(f/H) > 0，则该电流在西边界再循环，并且不会发生内部运动。如果 ?/?y(f/H) < 0，则添加东部边界流和内部环流。在均匀模型和双层模型中，自由射流都可以沿着临界线穿越海洋，其中 ?/?y(f/H) = 0。如果内部存在具有闭合 f/H 等值线的区域，则会将相应的环流添加到解中。对于同质海洋，该环流的环流变得非常强，对于两层海洋，该环流则变得很弱。在北大西洋，f/H 向北增加，闭合等值线仅存在于亚速尔群岛的一个区域。根据两层模型，深层运动应局限于循环的西边界流。亚速尔群岛附近可能存在深层反气旋环流，其喷流沿 2 公里等深线与西边界流相连。 DOI：10.1111/j.2153-3490.1968.tb00347.x
The effect of bottom topography is studied for homogeneous and two-layer oceans with Ekman-type dynamics. In the case where friction is important only at a lateral boundary explicit solutions are obtained. Cases in which friction becomes important also in the interior are discussed qualitatively. Essential differences are found between the solutions for the homogeneous and the two-layer oceans. In the homogeneous ocean a western or an eastern boundary current occurs when ?/?y(f/H) is positive and negative, respectively (f is the Coriolis parameter, H the depth, y a northward coordinate), and there is a Sverdrup type interior circulation modified by bottom topography. This case has been discussed previously in the literature. In the two-layer model with the upper layer thin compared to the lower layer the motion in the lower layer becomes small. The upper layer solution is similar to the one-layer solution given by Stommel (1948) with a western boundary current, with some modification due to finite distortions of the interface. In the lower layer there is also a western boundary current. If ?/?y(f/H) > 0 this current recirculates at the western boundary and no interior motion occurs. If ?/?y(f/H) < 0 an eastern boundary current as well as an interior circulation is added. In both the homogeneous and the two-layer models free jets can cross over the ocean along a critical line, where ?/?y(f/H) = 0. If a region with closed f/H -contours exists in the interior a corresponding gyre is added to the solution. The circulation in this gyre becomes very strong for the homogeneous ocean, weak for the two-layer ocean. In the North Atlantic f/H increases northward, and closed contours exist only in a region at the Azores. According to the two-layer model the deep motion should be confined to a recirculating western boundary current. A deep anticyclonic gyre could possibly be found near the Azores with a jet connecting to the western boundary current along the 2 km depth contour. DOI: 10.1111/j.2153-3490.1968.tb00347.x