Observed and modeled pathways of the Iceland Scotland Overflow Water in the eastern North Atlantic
Observed and modeled pathways of the Iceland Scotland Overflow Water in the eastern North Atlantic
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DOI：
10.1016/j.pocean.2017.10.003
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发表时间：
2017-04
影响因子：
4.1
通讯作者：
Sijia Zou;S. Lozier;W. Zenk;A. Bower;W. Johns
中科院分区：
文献类型：
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作者：
Sijia Zou;S. Lozier;W. Zenk;A. Bower;W. Johns
冰岛苏格兰溢流水（ISOW）在北大西洋东部的扩散主要是在欧拉框架下使用数值模型或仅限于少数地点的观测进行研究。迄今为止，还没有研究从欧拉和拉格朗日的角度对 ISOW 传播路径进行全面的描述。在本文中，我们结合了以前未报告的海流测量数据、水文数据、RAFOS 浮标数据和高分辨率 (1/12°) 数值海洋模型，从这两个角度研究 ISOW 的传播路径。我们在冰岛盆地中部（~59°N）确定了三个 ISOW 输运核心，其中主要核心沿着雷克雅内斯海岭（RR）东部边界，另外两个位于盆地内部。根据沿 59°N 观测到的和/或数值浮标的轨迹，我们还描述了 ISOW 传播路径并量化了它们的相对重要性。 10 年内，来自 59°N 的 7-11% 的 ISOW 通过查理吉布斯断裂带 (CGFZ) 北部 RR 的缺口逃逸到伊尔明格海；流过这些间隙的水主要来自沿 RR 东部边界的较浅的 ISOW 层。 10-13% 进一步向南移动，直到 CGFZ，在那里向西进入西副极地环流。 18-21% 的 ISOW 沿着大西洋中脊东侧向南扩散到西欧盆地 (WEB)。十年期间，大部分剩余水都留在冰岛盆地。基于模型的研究首次展示了这些 ISOW 路径的时间变异性。我们发现，向 WEB 输出的南向水的比例与通过 CGFZ 的输出呈反相关，这一结果被认为反映了这些路径与北大西洋洋流在幅度和/或位置变化方面的相互作用。
The spreading of Iceland Scotland Overflow Water (ISOW) in the eastern North Atlantic has largely been studied in an Eulerian frame using numerical models or with observations limited to a few locations. No study to date has provided a comprehensive description of the ISOW spreading pathways from both Eulerian and Lagrangian perspectives. In this paper, we use a combination of previously unreported current meter data, hydrographic data, RAFOS float data, and a high resolution (1/12°) numerical ocean model to study the spreading pathways of ISOW from both of these perspectives. We identify three ISOW transport cores in the central Iceland Basin (∼59°N), with the major core along the eastern boundary of the Reykjanes Ridge (RR) and the other two in the basin interior. Based on trajectories of observed and/or numerical floats seeded along 59°N, we also describe the ISOW spreading pathways and quantify their relative importance. Within 10 years, 7–11% of ISOW from 59°N escapes into the Irminger Sea via gaps in the RR north of the Charlie Gibbs Fracture Zone (CGFZ); the water that moves through these gaps principally originates from the shallower ISOW layer along the RR eastern boundary. 10–13% travels further southward until the CGFZ, where it crosses westward into the western subpolar gyre. 18–21% of ISOW spreads southward along the eastern flank of the Mid-Atlantic Ridge into the Western European Basin (WEB). Most of the remaining water stays in the Iceland Basin over the 10-year period. A model-based investigation provides a first look at the temporal variability of these ISOW pathways. We find that the fraction of southward water exported into the WEB is anti-correlated with the export through the CGFZ, a result assumed to reflect these pathways’ interactions with the North Atlantic Current in magnitude and/or position shift.