Dynamics of zonally elongated transient flows

M. V. Rudko, I. V. Kamenkovich

Research output: Contribution to journalArticlepeer-review

Abstract

This study examines the dynamics of zonally elongated transient flows (ZELTs) in the context of quasi-geostrophic turbulence. Unlike stationary zonal jets considered in previous studies, these flow features do not span the entire oceanic basin and propagate in the zonal direction at a speed slower than baroclinic Rossby waves. The analysis of potential vorticity balance in a statistically steady state shows that ZELTs are maintained by the vorticity flux divergences associated with the eddy-eddy interactions whereas the eddy-mean flow interactions play a secondary role. The divergences of the eddy fluxes of barotropic relative vorticity and buoyancy are shown to be the dominant contributors. The importance of specific eddy-eddy interactions are further studied using a dynamical model with the removed eddy-eddy vorticity flux divergences, which is equivalent to the fluid system with an absent cascade of eddy energy. Simulations with this reduced-dynamics model exhibit a complete disappearance of ZELTs, confirming the expectations from the analysis of the vorticity balance. Additional reduced-dynamics simulations demonstrate that the eddy kinetic energy transport leads to the emergence of ZELTs, with the transport in the baroclinic mode playing the leading role, while the potential energy transport acts to damp them.

Original languageEnglish (US)
Article numberA61
JournalJournal of Fluid Mechanics
Volume911
DOIs
StatePublished - 2021

Keywords

  • baroclinic flows
  • geostrophic turbulence
  • quasi-geostrophic flows

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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