Sensitivity of gyre-scale marine connectivity estimates to fine-scale circulation

IF 4.1 3区地球科学 Q2 METEOROLOGY & ATMOSPHERIC SCIENCES

Ocean Science Pub Date : 2023-08-04 DOI:10.5194/os-19-1183-2023

S. Hariri, S. Speich, B. Blanke, M. Lévy

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引用次数: 0

Abstract

Abstract. We investigated the connectivity properties of an idealized western boundary current system separating two ocean gyres, where the flow is characterized by a well-defined mean circulation as well as energetic fine-scale features (i.e., mesoscale and submesoscale currents). We used a time-evolving 3D flow field from a high-resolution (HR-3D) ocean model of this system. In order to evaluate the role of the fine scales in connectivity estimates, we computed Lagrangian trajectories in three different ways: using the HR-3D flow, using the same flow but filtered on a coarse-resolution grid (CR-3D), and using the surface layer flow only (HR-SL). We examined connectivity between the two gyres along the western boundary current and across it by using and comparing different metrics, such as minimum and averaged values of transit time between 16 key sites, arrival depths, and probability density functions of transit times. We find that when the fine-scale flow is resolved, the numerical particles connect pairs of sites faster (between 100 to 300 d) than when it is absent. This is particularly true for sites that are along and near the jets separating the two gyres. Moreover, the connectivity is facilitated when 3D instead of surface currents are resolved. Finally, our results emphasize that ocean connectivity is 3D and not 2D and that assessing connectivity properties using climatologies or low-resolution velocity fields yields strongly biased estimates.

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环流尺度海洋连通性估计对细尺度环流的敏感性

摘要我们研究了分离两个海洋环流的理想西边界流系统的连通性，该系统的流动具有定义良好的平均环流和高能精细尺度特征(即中尺度和亚中尺度流)。我们使用了来自该系统高分辨率(HR-3D)海洋模型的随时间变化的3D流场。为了评估细尺度在连通性估计中的作用，我们以三种不同的方式计算拉格朗日轨迹:使用HR-3D流、使用粗分辨率网格过滤的相同流(CR-3D)和仅使用表面层流(HR-SL)。我们通过使用和比较不同的指标，如16个关键地点之间的最小和平均传输时间值、到达深度和传输时间的概率密度函数，研究了沿西部边界流和穿越它的两个环流之间的连通性。我们发现，当细尺度流动被分解时，数值粒子连接对的速度比不存在时更快(在100到300天之间)。对于沿着和靠近分离两个环流的喷流的地点来说尤其如此。此外，当3D电流而不是表面电流被解析时，连接性更容易。最后，我们的研究结果强调，海洋连通性是3D的，而不是2D的，使用气候学或低分辨率速度场来评估连通性会产生严重的估计偏差。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Ocean Science 地学-海洋学

CiteScore

5.90

自引率

6.20%

发文量

审稿时长

6-12 weeks

期刊介绍： Ocean Science (OS) is a not-for-profit international open-access scientific journal dedicated to the publication and discussion of research articles, short communications, and review papers on all aspects of ocean science: experimental, theoretical, and laboratory. The primary objective is to publish a very high-quality scientific journal with free Internet-based access for researchers and other interested people throughout the world. Electronic submission of articles is used to keep publication costs to a minimum. The costs will be covered by a moderate per-page charge paid by the authors. The peer-review process also makes use of the Internet. It includes an 8-week online discussion period with the original submitted manuscript and all comments. If accepted, the final revised paper will be published online. Ocean Science covers the following fields: ocean physics (i.e. ocean structure, circulation, tides, and internal waves); ocean chemistry; biological oceanography; air–sea interactions; ocean models – physical, chemical, biological, and biochemical; coastal and shelf edge processes; paleooceanography.