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The merger of geophysical vortices at finite Rossby and Froude number

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The merger of geophysical vortices at finite Rossby and Froude number. / Reinaud, Jean N.; Dritschel, David G.

In: Journal of Fluid Mechanics, Vol. 848, 10.08.2018, p. 388-410.

Research output: Contribution to journalArticle

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Reinaud, JN & Dritschel, DG 2018, 'The merger of geophysical vortices at finite Rossby and Froude number' Journal of Fluid Mechanics, vol. 848, pp. 388-410. https://doi.org/10.1017/jfm.2018.367

APA

Reinaud, J. N., & Dritschel, D. G. (2018). The merger of geophysical vortices at finite Rossby and Froude number. Journal of Fluid Mechanics, 848, 388-410. https://doi.org/10.1017/jfm.2018.367

Vancouver

Reinaud JN, Dritschel DG. The merger of geophysical vortices at finite Rossby and Froude number. Journal of Fluid Mechanics. 2018 Aug 10;848:388-410. https://doi.org/10.1017/jfm.2018.367

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Reinaud, Jean N. ; Dritschel, David G. / The merger of geophysical vortices at finite Rossby and Froude number. In: Journal of Fluid Mechanics. 2018 ; Vol. 848. pp. 388-410.

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@article{2e2336a5191b4e0fab1c5f6e57896c02,
title = "The merger of geophysical vortices at finite Rossby and Froude number",
abstract = "We investigate the merger of two co-rotating geophysical vortices at finite Rossby and Froude number.  The initial conditions consist of two uniform potential vorticity vortices in near equilibrium and in a near 'balanced' state (i.e. with negligible emission of inertia-gravity wave radiation).  We determine the critical merger distance between the two vortices.  This distance is found to increase with the magnitude of the Rossby number: intense cyclones or intense anticyclones.  Note that the Froude number is proportional to the Rossby number for the near equilibrium initial conditions considered.  The critical merging distance also depends on the sign of the potential vorticity anomaly, which is positive for 'cyclones' and negative for 'anticyclones'.  We show ageostrophic motions occurring at finite Rossby number tend to draw cyclones together but draw anticyclones apart.  On the other hand, we show that anticyclones tend to deform more, in particular when subject to vertical shear (as when the vortices are vertically offset).  These two effects compete.  Overall, nearly aligned cyclones tend to merge from further apart than their anticyclonic counterparts, while vertically offset anticyclones merger from further apart than cyclones.",
keywords = "Rotating flows, Stratified flows, Vortex dynamics",
author = "Reinaud, {Jean N.} and Dritschel, {David G.}",
note = "Partial support for this research has come from the UK Engineering and Physical Sciences Research Council (grant number EP/H001794/1).",
year = "2018",
month = "8",
day = "10",
doi = "10.1017/jfm.2018.367",
language = "English",
volume = "848",
pages = "388--410",
journal = "Journal of Fluid Mechanics",
issn = "0022-1120",
publisher = "CAMBRIDGE UNIV PRESS",

}

RIS (suitable for import to EndNote) - Download

TY - JOUR

T1 - The merger of geophysical vortices at finite Rossby and Froude number

AU - Reinaud, Jean N.

AU - Dritschel, David G.

N1 - Partial support for this research has come from the UK Engineering and Physical Sciences Research Council (grant number EP/H001794/1).

PY - 2018/8/10

Y1 - 2018/8/10

N2 - We investigate the merger of two co-rotating geophysical vortices at finite Rossby and Froude number.  The initial conditions consist of two uniform potential vorticity vortices in near equilibrium and in a near 'balanced' state (i.e. with negligible emission of inertia-gravity wave radiation).  We determine the critical merger distance between the two vortices.  This distance is found to increase with the magnitude of the Rossby number: intense cyclones or intense anticyclones.  Note that the Froude number is proportional to the Rossby number for the near equilibrium initial conditions considered.  The critical merging distance also depends on the sign of the potential vorticity anomaly, which is positive for 'cyclones' and negative for 'anticyclones'.  We show ageostrophic motions occurring at finite Rossby number tend to draw cyclones together but draw anticyclones apart.  On the other hand, we show that anticyclones tend to deform more, in particular when subject to vertical shear (as when the vortices are vertically offset).  These two effects compete.  Overall, nearly aligned cyclones tend to merge from further apart than their anticyclonic counterparts, while vertically offset anticyclones merger from further apart than cyclones.

AB - We investigate the merger of two co-rotating geophysical vortices at finite Rossby and Froude number.  The initial conditions consist of two uniform potential vorticity vortices in near equilibrium and in a near 'balanced' state (i.e. with negligible emission of inertia-gravity wave radiation).  We determine the critical merger distance between the two vortices.  This distance is found to increase with the magnitude of the Rossby number: intense cyclones or intense anticyclones.  Note that the Froude number is proportional to the Rossby number for the near equilibrium initial conditions considered.  The critical merging distance also depends on the sign of the potential vorticity anomaly, which is positive for 'cyclones' and negative for 'anticyclones'.  We show ageostrophic motions occurring at finite Rossby number tend to draw cyclones together but draw anticyclones apart.  On the other hand, we show that anticyclones tend to deform more, in particular when subject to vertical shear (as when the vortices are vertically offset).  These two effects compete.  Overall, nearly aligned cyclones tend to merge from further apart than their anticyclonic counterparts, while vertically offset anticyclones merger from further apart than cyclones.

KW - Rotating flows

KW - Stratified flows

KW - Vortex dynamics

U2 - 10.1017/jfm.2018.367

DO - 10.1017/jfm.2018.367

M3 - Article

VL - 848

SP - 388

EP - 410

JO - Journal of Fluid Mechanics

T2 - Journal of Fluid Mechanics

JF - Journal of Fluid Mechanics

SN - 0022-1120

ER -

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ID: 252913149