Quantifying Eulerian Eddy Leakiness in An Idealized Model

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Authors

Tongya Liu , Ryan Abernathey , Anirban Sinha, Dake Chen

Abstract

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 SSHA 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, non-overlapping SSH eddies, and non-overlapping 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 non-overlapping SSH eddies, more water leakage (about 60\%) occurs at a faster rate. Following the number and radius of real 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 non-overlapping SSH eddies, suggesting that the material coherence properties of non-overlapping SSH eddies are not significantly different from random pieces of ocean with the same size.

DOI

https://doi.org/10.31223/osf.io/mwctf

Subjects

Oceanography, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics

Keywords

Coherent transport, Eddy leakiness, Eulerian eddies, Lagrangian eddies

Dates

Published: 2019-08-21 07:46

Last Updated: 2019-10-22 12:28

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License

GNU Lesser General Public License (LGPL) 2.1

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