Eddy momentum flux and its contribution to the Southern Ocean momentum balance
Eddy momentum flux and its contribution to the Southern Ocean momentum balance
复制标题
涡动量通量及其对南大洋动量平衡的贡献
作者：
R. Morrow;J. Church;R. Coleman;D. Chelton;N. White
强烈的西风将大量的动量转移到南大洋。分析和数值模型表明，瞬态涡流可能是重要的，在运输这种动量远离风强迫的区域，无论是水平1或垂直向下，它是由底部地形阻力平衡2 -5。然而，很少有长期的水平涡流动量通量的现场观测6 -8，也没有大规模的垂直涡流通量的测量，以测试这些模型。因此，南极绕极流（ACC）的动量平衡仍然不确定，涡旋的作用存在争议。在这里，我们使用Geosat卫星高度计数据来解决方向涡动动能和水平涡动动量通量在ACC精细的空间和时间尺度。海底地形对表层涡动动量通量复杂的空间分布有很大的影响。水平涡动动量通量一般倾向于集中的平均流，虽然观察到一些地区的分歧。我们的研究结果表明，纬向平均水平涡动量通量从瞬态涡是一个数量级太小，并在错误的方向，直接平衡东动量输入风1。
A LARGE amount of momentum is transferred to the Southern Ocean by strong westerly winds. Analytical and numerical models have suggested that transient eddies may be important in transporting this momentum away from the region of wind forcing, either horizontally1 or vertically downwards where it is balanced by bottom topographic drag2–5. There are, however, few long-term in situ observations of horizontal eddy momentum flux6–8, and no large-scale measurements of vertical eddy fluxes, to test these models. As a result, the momentum balance of the Antarctic circumpolar current (ACC) remains uncertain, and the role of eddies controversial. Here we use Geosat satellite altimeter data to resolve directional eddy kinetic energy and horizontal eddy momentum flux in the ACC on fine spatial and temporal scales. The complex spatial distribution of surface eddy momentum flux is strongly influenced by bottom topography. The horizontal eddy momentum flux tends generally to concentrate the mean flow, although some regions of divergence are observed. Our results show that the zonally averaged horizontal eddy momentum flux from transient eddies is an order of magnitude too small, and in the wrong direction to directly balance the eastward momentum input from wind1.