Properties of the Lateral Mesoscale Eddy-Induced Transport in a High-Resolution Ocean Model: Beyond the Flux–Gradient Relation
Properties of the Lateral Mesoscale Eddy-Induced Transport in a High-Resolution Ocean Model: Beyond the Flux–Gradient Relation
复制标题
高分辨率海洋模型中横向中尺度涡流引起的传输特性：超越通量梯度关系
DOI：
10.1175/jpo-d-22-0108.1
复制
发表时间：
2022
影响因子：
3.5
通讯作者：
Berloff, Pavel
中科院分区：
文献类型：
--
作者：
Lu, Yueyang;Kamenkovich, Igor;Berloff, Pavel
横向中尺度涡流引起的示踪剂传输传统上通过通量梯度关系在粗分辨率模型中表示。在最完整的形式中，该关系假设涡流示踪剂通量是大尺度示踪剂浓度梯度和涡流传输系数张量的乘积。然而，最近的几项研究报告说，张量具有显着的时空复杂性，并且没有唯一定义，也就是说，它对示踪剂分布和涡流的非发散（“旋转”）分量的存在敏感。这些问题可能会导致涡流引起的传输的表示出现重大偏差。使用墨西哥湾流区域的高分辨率示踪剂模型，我们检查了动态被动示踪剂的横向涡流引起的传输的扩散和平流特性，重新评估了通量梯度关系的效用，并提出了一种基于通过扩散和广义涡流引起的平流相结合来模拟局部涡流强迫的替代方法。中尺度涡流是通过基于尺度的空间过滤来定义的，这导致了新的涡流诱发项的重要性，包括涡流通量中的涡流平均协方差。结果表明，新方法显着减少了表示这些术语的偏差。高分辨率模型中的一系列有针对性的模拟进一步表明，该方法在再现涡流的搅拌和分散效果方面优于通量梯度模型。我们的研究表明，有可能升级传统的通量梯度关系来表示涡流引起的示踪剂输运。
Lateral mesoscale eddy-induced tracer transport is traditionally represented in coarse-resolution models by the flux–gradient relation. In its most complete form, the relation assumes the eddy tracer flux as a product of the large-scale tracer concentration gradient and an eddy transport coefficient tensor. However, several recent studies reported that the tensor has significant spatiotemporal complexity and is not uniquely defined, that is, it is sensitive to the tracer distributions and to the presence of nondivergent (“rotational”) components of the eddy flux. These issues could lead to significant biases in the representation of the eddy-induced transport. Using a high-resolution tracer model of the Gulf Stream region, we examine the diffusive and advective properties of lateral eddy-induced transport of dynamically passive tracers, reevaluate the utility of the flux–gradient relation, and propose an alternative approach based on modeling the local eddy forcing by a combination of diffusion and generalized eddy-induced advection. Mesoscale eddies are defined by a scale-based spatial filtering, which leads to the importance of new eddy-induced terms, including eddy-mean covariances in the eddy fluxes. The results show that the biases in representing these terms are noticeably reduced by the new approach. A series of targeted simulations in the high-resolution model further demonstrates that the approach outperforms the flux–gradient model in reproducing the stirring and dispersing effect of eddies. Our study indicates potential to upgrade the traditional flux–gradient relation for representing the eddy-induced tracer transport.