Genesis, evolution, and apocalypse of Loop Current rings

TL;DR

This study applies advanced objective methods to analyze the lifecycle of Loop Current rings in the Gulf of Mexico, revealing new insights into their genesis, evolution, and demise with improved robustness over traditional approaches.

Contribution

It introduces a technology that robustly and precisely frames vortex genesis and apocalypse using objective Lagrangian methods on satellite data.

Findings

Consistent results from stretching- and diffusion-based assessments

Eulerian assessments show large discrepancies with Lagrangian methods

Vorticity-based assessment indicates shorter vortex lifespans

Abstract

We carry out assessments of the life cycle of Loop Current vortices, so-called rings, in the Gulf of Mexico by applying three objective (i.e., observer-independent) coherent Lagrangian vortex detection methods on velocities derived from satellite altimetry measurements of sea-surface height (SSH). The methods reveal material vortices with boundaries that withstand stretching or diffusion, or whose fluid elements rotate evenly. This involved a technology advance that enables framing vortex genesis and apocalypse robustly and with precision. We find that the stretching- and diffusion-withstanding assessments produce consistent results, which show large discrepancies with Eulerian assessments that identify vortices with regions instantaneously filled with streamlines of the SSH field. The even-rotation assessment, which is vorticity-based, is found to be quite unstable, suggesting life expectancies much shorter than those produced by all other assessments.