Enduring Lagrangian coherence of a Loop Current ring assessed using independent observations

Ocean flows are routinely inferred from low-resolution satellite altimetry measurements of sea surface height assuming a geostrophic balance. Recent nonlinear dynamical systems techniques have revealed that surface currents derived from altimetry can support mesoscale eddies with material boundaries...

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Bibliographic Details
Published in:Scientific reports 2018-07, Vol.8 (1), p.11275-12, Article 11275
Main Authors: Beron-Vera, Francisco J., Olascoaga, María J., Wang, Yan, Triñanes, Joaquín, Pérez-Brunius, Paula
Format: Article
Language:English
Subjects:
639/705/1041
704/829/2737
Altimeters
Boundaries
Dynamical systems
Eddies
Humanities and Social Sciences
multidisciplinary
Ocean circulation
Satellite altimetry
Science
Science (multidisciplinary)
Water flow
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Summary:Ocean flows are routinely inferred from low-resolution satellite altimetry measurements of sea surface height assuming a geostrophic balance. Recent nonlinear dynamical systems techniques have revealed that surface currents derived from altimetry can support mesoscale eddies with material boundaries that do not filament for many months, thereby representing effective transport mechanisms. However, the long-range Lagrangian coherence assessed for mesoscale eddy boundaries detected from altimetry is constrained by the impossibility of current altimeters to resolve ageostrophic submesoscale motions. These may act to prevent Lagrangian coherence from manifesting in the rigorous form described by the nonlinear dynamical systems theories. Here we use a combination of satellite ocean color and surface drifter trajectory data, rarely available simultaneously over an extended period of time, to provide observational evidence for the enduring Lagrangian coherence of a Loop Current ring detected from altimetry. We also seek indications of this behavior in the flow produced by a data-assimilative system which demonstrated ability to reproduce observed relative dispersion statistics down into the marginally submesoscale range. However, the simulated flow, total surface and subsurface or subsampled emulating altimetry, is not found to support the long-lasting Lagrangian coherence that characterizes the observed ring. This highlights the importance of the Lagrangian metrics produced by the nonlinear dynamical systems tools employed here in assessing model performance.
ISSN:2045-2322
2045-2322
DOI:10.1038/s41598-018-29582-5