Relative dispersion and kinematic properties of the coastal submesoscale circulation in the southeastern Ligurian Sea

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

Ocean Science Pub Date : 2023-11-24 DOI:10.5194/os-19-1617-2023

P. Poulain, L. Centurioni, C. Brandini, Stefano Taddei, M. Berta, M. Menna

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引用次数: 0

Abstract

Abstract. An array of Lagrangian instruments (more than 100 drifters and a profiling float) were deployed for several days in the coastal waters of the southeastern Ligurian Sea to characterize the near-surface circulation at the submesoscale (< 10 km). The drifters were trapped in an offshore-flowing filament and a cyclonic eddy that developed at the southwestern extremity of the filament. Drifter velocities are used to estimate differential kinematic properties (DKPs) and the relative dispersion of the near-surface currents on scales as small as 100 m. The maximum drifter speed is ∼ 50 cm s−1. The DKPs within the cluster exhibit considerable spatial and temporal variability, with absolute values reaching the order of magnitude of the local inertial frequency. Vorticity prevails in the core of the cyclonic eddy, while strain is dominant at the outer edge of the eddy. Significant convergence was also found in the southwestern flow of the filament. The initial relative dispersion on small scales (100–200 m) is directly related to some of the DKPs (e.g., divergence, strain and instantaneous rate of separation). The mean squared separation distance (MSSD) grows exponentially with time, and the finite-size Lyapunov exponent (FSLE) is independent of scale. After 5–10 h of drift or for initial separations greater than 500 m, the MSSD and FSLE show smaller relative dispersion that decreases slightly with scale.

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利古里亚海东南部沿岸次中尺度环流的相对散布和运动特性

摘要在利古里亚海东南部沿岸水域部署了拉格朗日仪器阵列（100 多个漂流器和一个剖面浮标），以描述次中尺度（< 10 公里）的近表层环流特征。漂流器被困在离岸流动的细丝和在细丝西南端形成的旋涡中。漂流器速度用于估算微分运动特性（DKPs）和小至 100 米尺度的近表层海流的相对散布。最大漂移速度为 ∼ 50 cm s-1。集群内的 DKPs 表现出相当大的时空变异性，绝对值达到当地惯性频率的数量级。涡旋漩涡的核心区域以涡度为主，而漩涡的外围则以应变为主。在丝状西南气流中也发现了明显的辐合。小尺度（100-200 米）上的初始相对离散度与某些 DKPs（如发散、应变和瞬时分离率）直接相关。平均平方分离距离（MSSD）随时间呈指数增长，而有限尺寸李亚普诺夫指数（FSLE）与尺度无关。在漂移 5-10 小时后或初始分离距离大于 500 米时，MSSD 和 FSLE 显示出较小的相对离散性，并随着尺度的增大而略有减小。

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.