Forecasting Long-Lived Lagrangian Vortices from their Objective Eulerian Footprints

Abstract

We derive a non-dimensional metric to quantify the expected Lagrangian persistence of objectively defined Eulerian vortices in two-dimensional unsteady flows. This persistence metric is the averaged deviation of the vorticity from its spatial mean over the Eulerian vortex, normalized by the instantaneous material leakage from the Eulerian vortex. The metric offers a model-independent and frame-independent tool for uncovering the instantaneous Eulerian signature of long-lived Lagrangian vortices. Using satellite-derived ocean velocity data, we show that Lagrangian vortex-persistence predictions by our metric significantly outperform those inferred from other customary Eulerian diagnostics, such as the potential vorticity gradient and the Okubo-Weiss criterion.

References in corpus (5)

• Defining Coherent Vortices Objectively from the Vorticity
• Objective Eulerian Coherent Structures
• The life cycle of a coherent Lagrangian Agulhas ring
• Automated detection of coherent Lagrangian vortices in two-dimensional unsteady flows
• Polar rotation angle identifies elliptic islands in unsteady dynamical systems

Cited by in corpus (4)

• Finite-time Lyapunov exponents in the instantaneous limit and material transport
• Uncovering the Edge of the Polar Vortex
• Efficient Computation of Null-Geodesic with Applications to Coherent Vortex Detection
• Hyperbolic Covariant Coherent Structures in two dimensional flows