Pathways of cross-frontal exchange in the North Atlantic Current
Pathways of cross-frontal exchange in the North Atlantic Current
复制标题
北大西洋洋流跨锋面交换的途径
DOI：
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发表时间：
2001
期刊：
影响因子：
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通讯作者：
T. Rossby
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文献类型：
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作者：
S. Dutkiewicz;L. Rothstein;T. Rossby
北大西洋洋流（NAC）是北大西洋副热带环流和副极地环流之间边界的一部分。水流在地形上控制着静止的河曲，这些河曲似乎在生长和衰退。纽芬兰盆地海流以东的一个地区含有混合亚极地/亚热带性质的水，这表明NAC之间存在交换。这项研究考虑了1993年至1995年在NAC区域发射的等密度RAFOS浮标的数据。我们使用RAFOS数据来定义“锋面区”为最有可能发现急流的气压范围。这个定义需要一个纬度依赖性，因为NAC浅滩向北。比这个范围更浅和更深的漂浮物分别被定义为在副极地和亚热带一侧。这些定义被用来估计当前和其周围环境之间发生的混合，并估计两个环流之间的水包交换的相对量。只有少量的质量交换，从一个环流到另一个被发现，但有一个明显的不对称性，导致从副极地到副热带两侧的平均通量。我们还发现，花车花大量的时间在锋面区域，并经常交换之间的快速和缓慢移动的沃茨，特别是在曲流极值。扩散，而在射流中，导致涡流交叉锋面交换，这是重要的跨NAC的属性交换。
The North Atlantic Current (NAC) forms part of the boundary between the subtropical and subpolar gyres in the North Atlantic Ocean. The current has topographically controlled stationary meanders that appear to grow and decay. A region east of the current in the Newfoundland Basin contains water of mixed subpolar/subtropical properties, suggesting that there is exchange across the NAC. This study considers data from isopycnal RAFOS floats launched in the NAC region from 1993 to 1995. We use the RAFOS data to define the “frontal zone” as a pressure range where the jet is most likely to be found. This definition requires a latitudinal dependence as the NAC shoals to the north. Floats shallower and deeper than this range are defined to be on the subpolar and subtropical side, respectively. These definitions are used to estimate mixing that occurs between the current and its surroundings and to estimate the relative quantity of exchange of water parcels between the two gyres. Only small quantities of mass exchange from one gyre to the other are found, but there is a distinct asymmetry leading to a mean flux from the subpolar to subtropical sides. We also find that floats spend significant time in the frontal region and are frequently exchanged between fast and slow moving waters, particularly at the meander extrema. Diffusion, while in the jet, leads to eddy cross-frontal exchange which is important for the exchange of properties across the NAC.