Quantifying Eulerian Eddy Leakiness in an Idealized Model

Liu, Tongya; Abernathey, Ryan; Sinha, Anirban; Chen, Dake

doi:10.1029/2019jc015576

Cited by 25 publications

(26 citation statements)

References 48 publications

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“…Some recent articles highlighted the inherent limitations of tracking mesoscale eddies through altimetry and/or with SSH‐based techniques (e.g., Amores et al., 2018; Stegner et al., 2021). In addition, the classic vision of materially coherent mesoscale eddies has been questioned over the last decade, emphasizing the leakiness of such structures (e.g., Cetina‐Heredia et al., 2019; Liu et al., 2019). Furthermore, as the resolution of numerical models and observations increases, emerging submesoscale three‐dimensional circulations seem to play a preponderant role in shaping material patterns in the surface layers (e.g., Lévy et al., 2018; Uchida et al., 2019).…”

Section: Summary and Discussionmentioning

confidence: 99%

Oceanic Mesoscale Cyclones Cluster Surface Lagrangian Material

Vic

Hascoët

Gula

et al. 2022

Geophysical Research Letters

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Mesoscale eddies are ubiquitous features in the oceans and dominate the kinetic energy reservoir. They mostly arise from instabilities of large-scale persistent currents and have been routinely observed through satellite altimetry for almost three decades (Chelton et al., 2011). They play an active role in the transport of tracers, yet several questions on the underlying mechanisms of dispersion and their regional and global implications remain debated (e.g., Abernathey & Haller, 2018;Zhang et al., 2014).As put forward in McWilliams (2008), "almost all our understanding of eddy dynamics and phenomena has its roots in quasi-geostrophic theory". Indeed, the dominant instabilities of large-scale currents and the lifecycle of mesoscale eddies are well described by the quasi-geostrophic theory. This theory relies on several assumptions, a fundamental one being that the Rossby number of the flow (Ro), which compares the inertial force to the Coriolis force, is small (Ro < 0.1, e.g., Section 5.3 in Vallis, 2006). In the limit of Ro → 0, there is a perfect symmetry in the phenomenology of cyclones and anticyclones. For Ro = O(0.1), an asymmetry is observed to develop with a dominance of anticyclones over cyclones. Correspondingly, the probability density function of the relative vorticity of the flow is slightly skewed toward negative values (e.g., Polvani et al., 1994). Reasons for this dominance are manifold (see the discussion in Polvani et al., 1994), but the sole kinematic consequence of the emergence of inertial forces is the acceleration of anticyclones and the slowing down of cyclones (Penven et al., 2014). No further kinematic asymmetry emerges from the regime of Ro = O(0.1).Two mechanisms commonly invoked to explain asymmetrical effects in convergence and divergence in cyclones and anticyclones are eddy pumping and Ekman pumping (McGillicuddy, 2016). The former is active toward the beginning and the end of the eddy life cycle (e.g., Figure 4.21 in Flierl & McGillicuddy, 2002). When a

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Section: Summary and Discussionmentioning

confidence: 99%

Oceanic Mesoscale Cyclones Cluster Surface Lagrangian Material

Vic

Hascoët

Gula

et al. 2022

Geophysical Research Letters

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“…Thus, it is anticipated that these algorithms can be leveraged to compute CNOPs for more realistic models, paving the way for further exploration of paired eddies sensitivity in future studies. Furthermore, recent works have noted the significance of filamentary structures at the periphery of eddies in material transport (Liu & Abernathey, 2023; Liu et al., 2019). The findings of this study may hold important value for predicting material transport caused by eddies, presenting an interesting avenue for further research.…”

Section: Summary and Discussionmentioning

confidence: 99%

The Sensitive Area for Targeting Observations of Paired Mesoscale Eddies Associated With Sea Surface Height Anomaly Forecasts

Jiang,

Duan,

Wang

2024

JGR Oceans

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For paired mesoscale eddies, the most sensitive initial errors in relation to sea surface height anomaly (SSHA) forecasts are investigated by utilizing the conditional nonlinear optimal perturbation (CNOP) method in a two‐layer quasigeostrophic model and then the sensitive areas are identified accordingly. For counter‐rotating eddies, the CNOP initial errors primarily occur within the eddies themselves, especially in areas characterized by clear high‐to low‐velocity gradients, accompanied by shear structures; while for co‐rotating eddies, besides sharing the feature of the former, their CNOP initial errors also concentrate between the two eddies and are obliquely tangential to their boundaries with a positive and negative shear structure. The utility of the CNOP initial errors in determining the sensitive areas for target observation is assessed through observing system simulation experiments (OSSEs). The OSSEs indicate that giving priority to the implementation of target observations in the sensitive areas identified by large CNOP initial errors, whether within eddies or between two co‐rotating eddies, particularly with a specific array guided by the shear structure of CNOP initial errors, leads to a notable improvement in SSHA forecasting. Finally, the effectiveness of the target observations, especially within the sensitive area situated between two co‐rotating eddies, is interpreted from the perspective of barotropic instability. The results of this study offer valuable scientific insights into the targeted observation of paired mesoscale eddies. These findings have the potential to provide important guidance for initializating paired mesoscale eddies, ultimately contributing to improvements in SSHA forecast accuracy.

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“…Moreover, Liu et al (2019), who quantified the material coherence of Eulerian SSH eddies and rotationally coherent Lagrangian vortices detected using the LAVD method, showed that SSH eddies are highly leaky and do not maintain their material coherence over the detection time interval, as opposed to the Lagrangian coherent vortices that were detected based on the LAVD method. They also showed that the SSH eddies may be coherent in their core, but they also may not, making SSH eddies almost indiscernible from any other body of water in the ocean, in terms of material coherence.…”

Section: Detection Of Coherent Eddiesmentioning

confidence: 99%

Influence of Caribbean eddies on the Loop current system evolution

et al. 2023

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The Loop Current (LC) system dynamics are an essential component of the processes influencing circulation and transport in the Gulf of Mexico (GoM). The LC evolution is influenced by various factors, including the rich eddy field of the region and the flow exchange through the Yucatan Strait with the neighboring Caribbean Sea. These factors contribute to the complexity of the LC and, as a result, to the limitations in the predictability of the system. The focus of this study is to further elucidate the evolution of the LC, by quantifying the influence of coherent eddy fluxes originating in the Caribbean Sea. This is achieved by employing the Lagrangian-Averaged Vorticity Deviation (LAVD) method, an objective metric to evaluate eddy coherence in the Caribbean Sea that allows, for the first time, to quantify at different depths the evolution of coherent Caribbean eddies through the Yucatan Channel towards the GoM. The physical connectivity between the Caribbean Sea and the GoM is addressed using Lagrangian techniques to analyze processes that take place south of the Yucatan Channel and help quantify their strong relationship with the GoM eddy field. Coherent anticyclonic vorticity fluxes, as well as the net coherent anticyclonic volume transport between the Caribbean Sea and the GoM are associated with Loop Current Eddy (LCE) detachments through direct connectivity between the coherent Caribbean anticyclones and the forming LCE. The findings have important implications for understanding and predicting the LC system and the physical connectivity processes between the GoM and the Caribbean Sea.

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Quantifying Eulerian Eddy Leakiness in an Idealized Model

Cited by 25 publications

References 48 publications

Oceanic Mesoscale Cyclones Cluster Surface Lagrangian Material

Oceanic Mesoscale Cyclones Cluster Surface Lagrangian Material

The Sensitive Area for Targeting Observations of Paired Mesoscale Eddies Associated With Sea Surface Height Anomaly Forecasts

Influence of Caribbean eddies on the Loop current system evolution

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