Correlation-based flow decomposition and statistical analysis of the eddy forcing
Correlation-based flow decomposition and statistical analysis of the eddy forcing
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基于相关性的流动分解和涡强迫的统计分析
DOI：
10.1017/jfm.2021.604
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发表时间：
2021
影响因子：
3.7
通讯作者：
Agarwal N
中科院分区：
文献类型：
--
作者：
Agarwal N
我们提出了一个全面的研究中尺度涡强迫海洋提出空间局部过滤的高分辨率双环流海洋环流的解决方案，其大尺度和小尺度（涡）组件。大尺度分量主要由中纬度环流、西边界流及其高度瞬变的东向急流延伸所控制，涡动分量集中在东向急流周围并与之发生强烈的相互作用。这不同于现有的分解方法，例如经典的Reynolds分解和基于第一斜压Rossby变形半径的具有恒定滤波器尺寸的移动平均（空间）滤波。接下来，我们的动力学的影响所产生的涡强迫大尺度流动的相互时滞的空间相关性，制定产品积分特征。它的时间统计揭示了涡动强迫和诱导的大尺度位涡异常之间的因果关系-称为涡动后向散射。结果还证明了瞬态涡动强迫的重要性和涡动后向散射的时滞依赖性。我们认为，这些属性被认为是涡参数化方案。我们进一步使用分解的涡流场来增强粗分辨率海洋模型。增强的解在统计上再现了缺失的向东急流延伸，增强了其周围的涡旋活动，并恢复了基本的大规模低频变率。这证明了一个降阶的统计模拟的漩涡-一个新兴的方法，包括涡流效应在非涡流解决海洋模型。
We present a comprehensive study of the mesoscale eddy forcing in the ocean by proposing spatially local filtering of the high-resolution double-gyre ocean circulation solution into its large- and small-scale (eddy) components. The large-scale component is dominated by the mid-latitude gyres, the western boundary currents and their highly transient eastward jet extension; the eddy component is concentrated around the eastward jet and strongly interacts with it. The proposed decomposition method achieves flow filtering based on the local spatial correlations. This is different from the existing decomposition methods, e.g. classical Reynolds decomposition and moving-average (spatial) filtering with a constant filter size based on the first baroclinic Rossby deformation radius. Next, we characterize the dynamical impacts of the resulting eddy forcing on the large-scale flow in terms of their mutual time-lagged spatial correlations, formulated as product integral characteristics. Its temporal statistics uncover robust causality between the eddy forcing and the induced large-scale potential vorticity anomalies – referred to as the eddy backscatter. The results also prove the significance of the transient eddy forcing and the time lag dependence of the eddy backscatter. We argue that these properties are to be considered by eddy parametrization schemes. We further used the decomposed eddy fields to augment a coarse-resolution ocean model. The augmented solution statistically reproduces the missing eastward jet extension, enhances the eddy activities around it and recovers the essential large-scale low-frequency variability. This justifies a reduced-order statistical emulation of the eddies – an emerging methodology for including eddy effects in non-eddy-resolving ocean models.
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3.5
作者：
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