The life cycle of a coherent Lagrangian Agulhas ring

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

We document the long-term evolution of an Agulhas ring detected from satellite altimetry using a technique from nonlinear dynamical systems that enables objective (i.e., observer-independent) eddy framing. Such objectively detected eddies have Lagrangian (material) boundaries that remain coherent (unfilamented) over the detection period. The ring preserves a quite compact material entity for a period of about 2 years even after most initial coherence is lost within 5 months after detection. We attribute this to the successive development of short-term coherent material boundaries around the ring. These boundaries provide effective short-term shielding for the ring, which prevents a large fraction of the ring's interior from being mixed with the ambient turbulent flow. We show that such coherence regain events cannot be inferred from Eulerian analysis. This process is terminated by a ring-splitting event which marks the ring demise, near the South American coast. The genesis of the ring is characterized by a ring-merging event away from the Agulhas retroflection, followed by a 4 month-long partial coherence stage, scenario that is quite different than a current occlusion and subsequent eddy pinch off.

Original languageEnglish (US)
Pages (from-to)3944-3954
Number of pages11
JournalJournal of Geophysical Research C: Oceans
Volume121
Issue number6
DOIs
StatePublished - Jun 1 2016

Fingerprint

Life cycle
eddy
life cycle
cycles
rings
Eulerian analysis
Nonlinear dynamical systems
Regain
Long Term Evolution (LTE)
satellite altimetry
turbulent flow
Merging
Shielding
Turbulent flow
Coastal zones
Satellites
vortices
coast
material
occlusion

Keywords

  • Agulhas rings
  • coherent material eddies
  • transport

ASJC Scopus subject areas

  • Geochemistry and Petrology
  • Geophysics
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science
  • Oceanography

Cite this

The life cycle of a coherent Lagrangian Agulhas ring. / Wang, Y.; Beron-Vera, Francisco J; Olascoaga, Maria J.

In: Journal of Geophysical Research C: Oceans, Vol. 121, No. 6, 01.06.2016, p. 3944-3954.

Research output: Contribution to journalArticle

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