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Instabilities and layering of a heated laboratory anticyclone
Phys. Rev. Fluids 5, 063801 – Published 2 June, 2020
DOI: https://doi.org/10.1103/PhysRevFluids.5.063801
Abstract
We generate and observe large (∼1 m diameter) anticyclonic vortices in a stably stratified rotating tank that are neutrally buoyant. A nonaxisymmetric () instability quickly develops, leading to subvortices and fine-structured shed filaments. When heated with respect to their surroundings the vortex lenses behave much the same way but with two conspicuous additions. First, prominent early, is that the circumferential edge appears serrated with cusplike features from lateral intrusions, surmised to be due to thermal convection. Second, a stepped upper layer develops due to thermohaline diffusive convection. We see no evidence of layering in the nonheated cases, indicating that viscohaline double diffusion appears to be inoperative, likely prevented by a turbulent background. These observations are considered with respect to previous laboratory work as well as to geophysical vortices that are thermally distinct from their environs, such as Meddies.
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References (32)
- W. Thomson, Vibrations of a columnar vortex, Philos. Mag. 10, 155 (1880).
- D. G. Dritschel, The repeated filamentation of two-dimensional vorticity interfaces, J. Fluid Mech. 194, 511 (1988).
- R. C. Kloosterziel and G. J. F. van Heijst, An experimental study of unstable barotropic vortices in a rotating fluid, J. Fluid Mech. 223, 1 (1991).
- E. J. Hopfinger and G. J. F. van Heijst, Vortices in rotating fluids, Annu. Rev. Fluid Mech. 25, 241 (1993).
- P. M. Saunders, The instability of a baroclinic vortex, J. Phys. Ocean. 3, 61 (1973).
- R. W. Griffiths and P. F. Linden, The stability of vortices in a rotating, stratified fluid, J. Fluid Mech. 105, 283 (1981).
- E. Thivolle-Cazat, J. Sommeria, and M. Galmiche, Baroclinic instability of two-layer vortices in laboratory experiments, J. Fluid Mech. 544, 69 (2005).
- K. Hedstrom and L. Armi, An experimental study of homogenous lenses in a stratified rotating fluid, J. Fluid Mech. 191, 535 (1988).
- A. E. Gill, Homogeneous intrusions in a rotating stratified fluid, J. Fluid Mech. 103, 275 (1981).
- G. Facchini and M. Le Bars, On the lifetime of a pancake anticyclone in a rotating stratified flow, J. Fluid Mech. 804, 688 (2016).
- M. E. McIntyre, Diffusive destabilisation of the baroclinic circular vortex, Geophys. Fluid Dyn. 1, 19 (1970).
- D. J. Baker, Density gradients in a rotating stratified fluid: experimental evidence for a new instability, Science 172, 1029 (1971).
- J. Calman, Experiments on high Richardson number instability of a rotating stratified shear flow, Dyn. Atmos. Oceans 1, 277 (1977).
- H. Stommel, A. B. Arons, and D. Blanchard, An oceanographic curiosity: the perpetual salt fountain, Deep-Sea Res. 3, 152 (1953).
- T. Radko, Double-Diffusive Convection (Cambridge University Press, Cambridge, UK, 2013).
- D. E. Kelly, H. J. S. Fernando, A. E. Gargett, J. Tanny, and E. Ozsoy, The diffusive regime of double-diffusive convection, Prog. Ocean. 56, 461 (2003).
- J. Turner, The coupled turbulent transports of salt and heat across a sharp density interface, Int. J. Heat Mass Transfer 8, 759 (1965).
- T. Radko, Thermohaline layering in dynamically and diffusively stable shear flows, J. Fluid Mech. 805, 147 (2016).
- L. Armi, D. Hebert, N. Oakey, J. Price, P. L. Richardson, T. Rossby, and B. Ruddick, Two years in the life of a Mediterranean salt lens, J. Phys. Ocean. 19, 354 (1989); K. Schultz Tokos, and T. Rossby, Kinematics and dynamics of a Mediterranean salt lens, ibid. 21, 879 (1991).
- C. Papenberg, D. Klaeschen, G. Krahmann, and R. W. Hobbs, Ocean temperature and salinity inverted from combined hydrographic and seismic data, Geophys. Res. Lett. 37, L04601 (2010); B. L. Hua, C. Ménesguen, S. Le Gentil, R. Schopp, B. Marsset, and H. Aiki, Layering and turbulence surrounding an anticyclonic vortex: in situ observations and quasi-geostrophic numerical simulations, J. Fluid Mech. 731, 418 (2013); T. Meunier, C. Ménesguen, R. Schopp, and S. Le Gentil, Tracer stirring around a meddy: the formation of layering, J. Phys. Ocean. 45, 407 (2015).
- H. Song, L. M. Pinheiro, B. Ruddick, and F. C. Teixeira, Meddy, spiral arms, and mixing mechanisms viewed by seismic imaging in the Tagus Abyssal Plain (SW Iberia), J. Marine Res. 69, 827 (2011).
- B. Ruddick, Intrusive mixing in a Mediterranean salt lens – intrusion slopes and dynamical mechanisms, J. Phys. Ocean. 22, 1274 (1992).
- T. Radko and C. Sisti, Life and demise of intrathermocline mesoscale vortices, J. Phys. Ocean. 47, 3087 (2017).
- http://www.legi.grenoble-inp.fr/web/spip.php?article757.
- O. Praud, A. M. Fincham, and J. Sommeria, Decaying grid turbulence in a strongly stratified fluid, J. Fluid Mech. 522, 1 (2005).
- E. Yim, P. Billant, and C. Ménesguen, Stability of an isolated pancake vortex in continuously stratified-rotating fluids, J. Fluid Mech. 801, 508 (2016).
- B. A. Storer, F. J. Poulin, and C. Ménesguen, The dynamics of quasigeostrophic lens-shaped vortices, J. Phys. Ocean. 48, 937 (2018).
- N. C. Shibley and M.-L. Timmermans, The formation of double-diffusive layers in a weakly turbulent environment, JGR Oceans 124, 1445 (2019).
- W. J. Merryfield, Origin of thermohaline staircases, J. Phys. Ocean. 30, 1046 (2000).
- P. Hassanzadeh, P. S. Marcus, and P. Le Gal, The universal aspect ratio of vortices in rotating stratified flows: theory and simulation, J. Fluid Mech. 706, 46 (2012); O. Aubert, M. Le Bars, P. Le Gal, and P. S. Marcus, The universal aspect ratio of vortices in rotating stratified flows: experiments and observations, ibid. 706, 34 (2012).
- R. Moll and P. Garaud, The effect of rotation on oscillatory double-diffusive convection (semiconvection), Astrophys. J. 834, 44 (2017).
- P. Garaud, Double-diffusive convection at low Prandtl number, Annu. Rev. Fluid Mech. 50, 275 (2018).
