Role of eddies in the maintenance of multiple jets embedded in eastward and westward baroclinic shears

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Title: Role of eddies in the maintenance of multiple jets embedded in eastward and westward baroclinic shears
Authors: Khatri, H
Berloff, P
Item Type: Journal Article
Abstract: Multiple zonal jets observed in many parts of the global ocean are often embedded in large-scale eastward and westward vertically sheared background flows. Properties of the jets and ambient eddies, as well as their dynamic interactions, are found to be different between eastward and westward shears. However, the impact of these differences on overall eddy dynamics remains poorly understood and is the main subject of this study. The roles of eddy relative vorticity and buoyancy fluxes in the maintenance of oceanic zonal jets are studied in a two-layer quasigeostrophic model. Both eastward and westward uniform, zonal vertically sheared cases are considered in the study. It is shown that, despite the differences in eddy structure and local characteristics, the fundamental dynamics are essentially the same in both cases: the relative-vorticity fluxes force the jets in the entire fluid column, and the eddy-buoyancy fluxes transfer momentum from the top to the bottom layer, where it is balanced by bottom friction. It is also observed that the jets gain more energy via Reynolds stress work in the layer having a positive gradient in the background potential vorticity, and this is qualitatively explained by a simple reasoning based on Rossby wave group velocity.
Issue Date: 1-Dec-2018
Date of Acceptance: 8-Nov-2018
URI: http://hdl.handle.net/10044/1/67204
DOI: https://dx.doi.org/10.3390/fluids3040091
ISSN: 2311-5521
Publisher: MDPI
Journal / Book Title: Fluids
Volume: 3
Issue: 4
Copyright Statement: © 2018 The Author(s). This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0 - https://creativecommons.org/licenses/by/4.0/).
Sponsor/Funder: Natural Environment Research Council (NERC)
Funder's Grant Number: NE/R011567/1
Keywords: Science & Technology
Physical Sciences
Physics, Fluids & Plasmas
Physics
ocean jets
quasigeostrophic model
eddy fluxes
baroclinic shear
DRIVEN BANDED JETS
ZONAL JETS
BETA-PLANE
SPECTRAL-ANALYSIS
TURBULENCE
MODEL
CIRCULATION
FLOWS
MECHANISM
DYNAMICS
Publication Status: Published
Article Number: 91
Online Publication Date: 2018-11-11
Appears in Collections:Mathematics
Centre for Environmental Policy
Applied Mathematics and Mathematical Physics
Faculty of Natural Sciences



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