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dc.contributor.authorBurgess, B. H.
dc.contributor.authorDritschel, David Gerard
dc.identifier.citationBurgess , B H & Dritschel , D G 2022 , ' Potential vorticity fronts and the late-time evolution of large-scale quasi-geostrophic flows ' , Journal of Fluid Mechanics , vol. 939 , A40 .
dc.identifier.otherPURE: 277929743
dc.identifier.otherPURE UUID: f3fa6731-a0be-4d9e-a7fd-57ae1d119252
dc.identifier.otherORCID: /0000-0001-6489-3395/work/111210117
dc.identifier.otherORCID: /0000-0001-9297-8003/work/111210263
dc.identifier.otherWOS: 000776652500001
dc.identifier.otherScopus: 85128472794
dc.descriptionFunding: BHB acknowledges support for this research from a Leverhulme Trust Early Career Fellowship.en
dc.description.abstractThe late-time behaviour of freely evolving quasi-geostrophic flows with initial characteristic length scale L0 larger than or equal to the deformation radius LD, L0/LD≥1 , is studied. At late time the flows are dominated by large multi-level vortices consisting of ascending terraces of well-mixed potential vorticity (PV), i.e. PV staircases. We examine how the number of mixed PV levels depends on the initial conditions, in particular L0/LD . For sufficiently large values of L0/LD≈5 , a complete staircase with regular steps forms, but as L0/LD decreases, the staircase becomes more irregular, with fewer mixed levels and the appearance of a large step centred on zero PV, corresponding to large regions of near-zero PV separating the multi-level vortices. This occurs because weak PV features in the initial field with scales smaller than LD undergo filamentation and are coarse-grained away or homogenised. For all values of L0/LD considered, inverse cascades of potential energy commence at sufficiently late times. The onset of these cascades, even when the flow is initialised well within the ‘asymptotic model’ (AM) regime, suggests that the AM regime is not self-consistent: when potential vorticity fronts are well-resolved, frontal dynamics eventually drive ongoing flow evolution.
dc.relation.ispartofJournal of Fluid Mechanicsen
dc.rightsCopyright © The Author(s), 2022. Published by Cambridge University Press. This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (, which permits unrestricted re-use, distribution, and reproduction in any medium, provided the original work is properly cited.en
dc.subjectGeostrophic turbulenceen
dc.subjectQuasi-geostrophic flowsen
dc.subjectShallow water flowsen
dc.subjectGE Environmental Sciencesen
dc.subjectQA Mathematicsen
dc.subjectQC Physicsen
dc.titlePotential vorticity fronts and the late-time evolution of large-scale quasi-geostrophic flowsen
dc.typeJournal articleen
dc.contributor.sponsorThe Leverhulme Trusten
dc.description.versionPublisher PDFen
dc.contributor.institutionUniversity of St Andrews. Applied Mathematicsen
dc.contributor.institutionUniversity of St Andrews. Marine Alliance for Science & Technology Scotlanden
dc.contributor.institutionUniversity of St Andrews. Scottish Oceans Instituteen
dc.description.statusPeer revieweden

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