Retention and Leakage of Water by Mesoscale Eddies in the East Australian Current System

Cetina‐Heredia, Paulina; Roughan, Moninya; Sebille, Erik van; Keating, Shane R.; Brassington, Gary B.

doi:10.1029/2018jc014482

Cited by 27 publications

(33 citation statements)

References 83 publications

(150 reference statements)

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“…Comparing with SSH eddies, the mean RCLV radius (35.5 km) is approximately about half of the mean SSH eddy radius (72.4 km). Similar to this result, Cetina-Heredia et al (2019) showed that the solid body rotation radius is 0.6 and 0.5 the radius of anticyclonic and cyclonic eddies detected from velocity fields, respectively. In contrast with Abernathey and Haller (2018), no significant latitude dependence or relationship with deformation radius is visible in either RCLVs or SSH eddies.…”

Section: Radius Propagation Speed and Zonal Coherent Transportsupporting

confidence: 85%

Quantifying Eulerian Eddy Leakiness in An Idealized Model

Liu¹,

Abernathey²,

Sinha³

et al. 2019

Preprint

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An idealized eddy‐resolving ocean basin, closely resembling the North Pacific Ocean, is simulated using MITgcm. We identify rotationally coherent Lagrangian vortices (RCLVs) and sea surface height (SSH) eddies based on the Lagrangian and Eulerian framework, respectively. General statistical results show that RCLVs have a much smaller coherent core than SSH eddies with the ratio of radius is about 0.5. RCLVs are often enclosed by SSH anomaly contours, but SSH eddy identification method fails to detect more than half of RCLVs. Based on their locations, two types of eddies are classified into three categories: overlapping RCLVs and SSH eddies, nonoverlapping SSH eddies, and nonoverlapping RCLVs. Using Lagrangian particles, we examine the processes of leakage and intrusion around SSH eddies. For overlapping SSH eddies, over the lifetime, the material coherent core only accounts for about 25% and about 50% of initial water leak from eddy interior. The remaining 25% of water can still remain inside the boundary, but only in the form of filaments outside the coherent core. For nonoverlapping SSH eddies, more water leakage (about 60%) occurs at a faster rate. Guided by the number and radius of SSH eddies, fixed circles and moving circles are randomly selected to diagnose the material flux around these circles. We find that the leakage and intrusion trends of moving circles are quite similar to that of nonoverlapping SSH eddies, suggesting that the material coherence properties of nonoverlapping SSH eddies are not significantly different from random pieces of ocean with the same size.

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Section: Radius Propagation Speed and Zonal Coherent Transportsupporting

confidence: 85%

Quantifying Eulerian Eddy Leakiness in An Idealized Model

Liu¹,

Abernathey²,

Sinha³

et al. 2019

Preprint

View full text Add to dashboard Cite

show abstract

“…Comparing with SSH eddies, the mean RCLV radius (35.5 km) is approximately about half of the mean SSH eddy radius (72.4 km). Similar to this result, Cetina‐Heredia et al () showed that the solid body rotation radius is 0.6 and 0.5 the radius of anticyclonic and cyclonic eddies detected from velocity fields, respectively. In contrast with Abernathey and Haller (), no significant latitude dependence or relationship with deformation radius is visible in either RCLVs or SSH eddies.…”

Section: Census Of Lagrangian Vortices and Eulerian Eddiessupporting

confidence: 77%

“…However, Abernathey and Haller () concluded that RCLVs uniformly live shorter than SSH eddies and they only identified 1 RCLV with lifetime of 270 days in the eastern Pacific over more 20 years, against the number of 2,076 in the SSH eddy data set (Chelton et al ()). Also, Cetina‐Heredia et al () found eddies retain water for several months most commonly in the east Australian current system, some also retain water over a year but these are less frequent (their Figure ). In this study, therefore, we excluded the long‐lived eddies and focus on coherent eddies with lifetime shorter than 90 days.…”

Section: Discussionmentioning

confidence: 99%

“…However, several works (e.g., Wang et al (), Abernathey and Haller ()) using Lagrangian frameworks indicate these Eulerian methods strongly overestimate the degree of eddy material transport. Additionally, Cetina‐Heredia et al () adopted Eulerian and Lagrangian approaches to highlight the potential of eddies to impact the environment depends upon whether they maintain water inside2 or leak it. In this study, we explored the relationship between eddy detection methods and coherent material transport and quantitatively calculated the leakiness of Eulerian eddies.…”

Section: Discussionmentioning

confidence: 99%

“…Similarly, the work of Beron‐Vera et al (), Froyland et al ()) and Wang et al (, ) examined the ability of Agulhas rings to coherently carry Agulhas leakage water using Lagrangian methods, finding considerably smaller transport estimates than previous Eulerian‐based methods. Most recently, Cetina‐Heredia et al () quantified the time that mesoscale eddies along the southeast coast of Australia retain water and pointed out the change in eddy shape relates to water exchange between the eddy interior and the background flow. Though Eulerian eddies can temporarily trap and transport water parcels and tracers (Gaube et al (); Condie and Condie ()), under the effects of stretching and filamentation, such eddies may lose coherence and experience leakage and deformation in the turbulent flow(Haller (); Early et al ().…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Quantifying Eulerian Eddy Leakiness in an Idealized Model

et al. 2019

View full text Add to dashboard Cite

An idealized eddy-resolving ocean basin, closely resembling the North Pacific Ocean, is simulated using MITgcm. We identify rotationally coherent Lagrangian vortices (RCLVs) and sea surface height (SSH) eddies based on the Lagrangian and Eulerian framework, respectively. General statistical results show that RCLVs have a much smaller coherent core than SSH eddies with the ratio of radius is about 0.5. RCLVs are often enclosed by SSH anomaly contours, but SSH eddy identification method fails to detect more than half of RCLVs. Based on their locations, two types of eddies are classified into three categories: overlapping RCLVs and SSH eddies, nonoverlapping SSH eddies, and nonoverlapping RCLVs. Using Lagrangian particles, we examine the processes of leakage and intrusion around SSH eddies. For overlapping SSH eddies, over the lifetime, the material coherent core only accounts for about 25% and about 50% of initial water leak from eddy interior. The remaining 25% of water can still remain inside the boundary, but only in the form of filaments outside the coherent core. For nonoverlapping SSH eddies, more water leakage (about 60%) occurs at a faster rate. Guided by the number and radius of SSH eddies, fixed circles and moving circles are randomly selected to diagnose the material flux around these circles. We find that the leakage and intrusion trends of moving circles are quite similar to that of nonoverlapping SSH eddies, suggesting that the material coherence properties of nonoverlapping SSH eddies are not significantly different from random pieces of ocean with the same size. Plain Language SummaryMaterial coherent transport is widely estimated based on the Eulerian methods, but the organization of Eulerian eddies determines Eulerian eddies cannot keep material coherence during the lifespan. In this study, we examine the relationship between eddy detection methods and material coherent transport and quantitatively estimate the Eulerian eddy leakiness in material transport. We compare the statistical features of rotationally coherent Lagrangian vortices and sea surface height (SSH) eddies identified from a high-resolution idealized model based on two different frameworks. We find that the Eulerian method fails to detect many Lagrangian structures and overestimate the real coherent core. Besides, using Lagrangian particles, we quantify the material flux across SSH eddies boundaries. Our results suggest that SSH eddies are far from coherent structures, with the leakage of initial water reach at least 50%. We also find that one type of SSH eddies is not significantly different from random pieces of ocean with the same size in material coherence properties. Our findings suggest that using Eulerian eddy boundaries to estimate coherent transport may be misleading.of coherent eddy transport based on different identification methods vary dramatically. In this paper, we aim to clarify the relationship between eddy identification methods and material coherent transport. Also, we seek to examine the extent to which the eddie...

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