On the spreading of South Atlantic Water into the Northern Hemisphere
On the spreading of South Atlantic Water into the Northern Hemisphere
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DOI：
10.1029/2008jc005165
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发表时间：
2009-05-19
影响因子：
3.6
通讯作者：
Boening, Claus W.
中科院分区：
文献类型：
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作者：
Kirchner, Kerstin;Rhein, Monika;Boening, Claus W.
北大西洋纬向翻转环流的上分支是由来自南半球的各种水团的越赤道输送补给的。在这里，我们研究了南大西洋水（SAW）从赤道到北纬25度进入热带北大西洋西部的大规模扩散。SAW在上层海洋水体的分数进行了量化，使用水团分析的数据集的电导率，温度，深度数据从Hydrobase项目和阿尔戈浮标程序。为了填补数据覆盖范围中的空白并深入了解所涉及的机制，观测结果得到了高分辨率连锁大西洋模型实验系列模型（1/12度）的结果的补充，该模型已被证明可以真实地模拟SAW的流入加勒比海。分析揭示了平均SAW传播途径在北大西洋，并确定最大的变化区域。温跃层和中心水层中的高SAW分数仅限于10 ° N以南的区域，其中水体由80%-90%的SAW组成。因此，赤道环流中的纬向流主要由表面声波形成。中间层中较弱的电流与北赤道电流的向北偏移相结合，使得该层中的SAW与上面的层相比侵入更北。在中间层，从北纬12度到北纬20度逐渐过渡到北大西洋水。
The upper branch of the meridional overturning circulation in the North Atlantic is fed by cross-equatorial transport of various water masses from the Southern Hemisphere. Here, we study the large-scale spreading of South Atlantic Water (SAW) into the western tropical North Atlantic from the equator to 25 degrees N. The fractions of SAW in the upper ocean water masses are quantified using a water mass analysis applied on a data set of conductivity-temperature-depth data from the Hydrobase project and the Argo float program. To fill gaps in the data coverage and to gain insight into the mechanisms involved, the observations are complemented with results from the high-resolution Family of Linked Atlantic Model Experiments model (1/12 degrees), which has been shown to realistically simulate the inflow of SAW into the Caribbean. The analysis reveals the mean SAW propagation pathways in the North Atlantic and identifies the regions of largest variability. High SAW fractions in the thermocline and central water layers are limited to the region south of 10 degrees N, where the water body consists of 80%-90% SAW. Thus, the zonal currents in the equatorial gyre are mainly formed of SAW. The weaker currents in the intermediate layer combined with a northward excursion of the North Equatorial Current allow the SAW in this layer to intrude farther north compared to the layers above. The transition into North Atlantic Water occurs gradually from 12 degrees N to 20 degrees N in the intermediate layer.