Unraveling the choice of the north Atlantic subpolar gyre index.,Scientific Reports

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Unraveling the choice of the north Atlantic subpolar gyre index.
Scientific Reports ( IF 3.8 ) Pub Date : 2020-01-22 , DOI: 10.1038/s41598-020-57790-5
Vimal Koul _{1,

2,

3} , Jan-Erik Tesdal ₄ , Manfred Bersch ₁ , Hjálmar Hátún ₅ , Sebastian Brune ₁ , Leonard Borchert _{1,

6,

7} , Helmuth Haak ₆ , Corinna Schrum _{1,

3} , Johanna Baehr ₁

Affiliation

The north Atlantic subpolar gyre (SPG) has been widely implicated as the source of large-scale changes in the subpolar marine environment. However, inconsistencies between indices of SPG-strength have raised questions about the active role SPG-strength and size play in determining water properties in the eastern subpolar North Atlantic (ENA). Here, by analyzing various SPG indices derived from observations and a global coupled model, we show that the choice of the SPG index dictates the interpretation of SPG strength-salinity relationship in the ENA. Variability in geostrophic currents derived from observed hydrography and model based Lagrangian trajectories reveal zonal shifts of advective pathways in the ENA and meridional shifts in the western intergyre region. Such shifts in advective pathways are manifestations of variability in the size and strength of the SPG, and they impact salinity by modulating the proportion of subpolar and subtropical waters reaching the ENA. SPG indices based on subsurface density and principal component analysis of sea surface height variability capture these shifts in advective pathways, and are therefore best suited to describe SPG-salinity relationship in the ENA. Our results establish the dynamical constraints on the choice of the SPG index and emphasize that SPG indices should be cautiously interpreted.

中文翻译：

阐明北大西洋次极回旋指数的选择。

北大西洋次极环流（SPG）已被广泛认为是次极海洋环境大规模变化的根源。但是，SPG强度指标之间的不一致引起了人们对SPG强度和大小在确定北亚极东部东部（ENA）的水属性中所起的积极作用的疑问。在这里，通过分析从观测值和整体耦合模型得出的各种SPG指数，我们表明SPG指数的选择决定了ENA中SPG强度与盐度关系的解释。从观测到的水文和基于模型的拉格朗日轨迹得出的地转流的变化揭示了ENA中对流路径的纬向位移和西部旋回区的子午线位移。对流路径的这种变化是SPG大小和强度变化的体现，并且它们通过调节到达ENA的亚极水和亚热带水的比例来影响盐度。基于地下密度和海面高度变化的主成分分析的SPG指数捕获了对流路径中的这些变化，因此最适合描述ENA中的SPG-盐度关系。我们的结果建立了SPG指数选择的动态约束，并强调应该谨慎解释SPG指数。基于地下密度和海面高度变化的主成分分析的SPG指数捕获了对流路径中的这些变化，因此最适合描述ENA中的SPG-盐度关系。我们的结果建立了SPG指数选择的动态约束，并强调应该谨慎解释SPG指数。基于地下密度和海面高度变化的主成分分析的SPG指数捕获了对流路径中的这些变化，因此最适合描述ENA中的SPG-盐度关系。我们的结果建立了SPG指数选择的动态约束，并强调应该谨慎解释SPG指数。

更新日期：2020-01-23

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