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Cyclonic circulation of Saturn’s atmosphere due to tilted convection

Abstract

Saturn displays cyclonic vortices at its poles and the general atmospheric circulation at other latitudes is dominated by embedded zonal jets that display cyclonic circulation. The abundance of small-scale convective storms suggests that convection plays a role in producing and maintaining Saturn’s atmospheric circulation. However, the dynamical influence of small-scale convection on Saturn’s general circulation is not well understood. Here we present laboratory analogue experiments and propose that Saturn’s cyclonic circulation can be explained by tilted convection in which buoyancy forces do not align with the planet’s rotation axis. In our experiments—conducted with a cylindrical water tank that is heated at the bottom, cooled at the top and spun on a rotating table—warm rising plumes and cold sinking water generate small anticyclonic and cyclonic vortices that are qualitatively similar to Saturn’s convective storms. Numerical simulations complement the experiments and show that this small-scale convection leads to large-scale cyclonic flow at the surface and anticyclonic circulation at the base of the fluid layer, with a polar vortex forming from the merging of smaller cyclonic storms that are driven polewards.

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Fig. 1: Experimental set-up and observations.
Fig. 2: A schematic drawing of a convecting layer of water in a rotating tank.
Fig. 3: Temperature and surface elevation fields at the surface of the convecting fluid in the numerical simulations.
Fig. 4: Profiles of the azimuthal velocity.

References

  1. 1.

    Dyudina, U. A. et al. Dynamics of Saturn’s south polar vortex. Science 319, 1801 (2008).

    Article  Google Scholar 

  2. 2.

    Boubnov, B. M. & Golitsyn, G. S. Experimental study of convective structures in rotating fluids. J. Fluid Mech. 167, 503–531 (1986).

    Article  Google Scholar 

  3. 3.

    Fernando, H. J. S., Chen, R.-R. & Boyer, D. L. Effects of rotation on convective turbulence. J. Fluid Mech. 228, 513–547 (1991).

    Google Scholar 

  4. 4.

    Maxworthy, T. & Narimousa, S. Unsteady, turbulent convection into a homogeneous, rotating fluid, with oceanographic applications. J. Phys. Oceanogr. 24, 865–887 (1994).

    Article  Google Scholar 

  5. 5.

    Condie, S. A. & Rhines, P. B. A convective model for the zonal jets in the atmospheres of Jupiter and Saturn. Nature 367, 711–713 (1994).

    Article  Google Scholar 

  6. 6.

    Read, P. L. et al. Dynamics of convectively driven banded jets in the laboratory. J. Atmos. Sci. 64, 4031–4052 (2007).

    Article  Google Scholar 

  7. 7.

    Stewartson, K. On the slow motion of an ellipsoid in a rotating fluid. Q. J. Mech. Appl. Maths 6, 141–162 (1953).

    Article  Google Scholar 

  8. 8.

    Loper, D. E. On the structure of a Taylor column driven by a buoyant parcel in an unbounded rotating fluid. J. Fluid Mech. 427, 131–165 (2001).

    Article  Google Scholar 

  9. 9.

    Sheremet, V. A. Laboratory experiments with tilted convective plumes on a centrifuge: a finite angle between the buoyancy force and the axis of rotation. J. Fluid Mech. 506, 217–244 (2004).

    Article  Google Scholar 

  10. 10.

    Davidson, P. A. The dynamics and scaling laws of planetary dynamos driven by inertial waves. Geophys. J. Int. 198, 1832–1847 (2014).

    Article  Google Scholar 

  11. 11.

    O’Neill, M. E., Emanuel, K. A. & Flierl, G. R. Polar vortex formation in giant-planet atmospheres due to moist convection. Nat. Geosci. 8, 523–526 (2015).

    Article  Google Scholar 

  12. 12.

    Rossby, C. G. On displacements and intensity changes of atmospheric vortices. J. Mar. Res. 7, 175–187 (1948).

    Google Scholar 

  13. 13.

    Flor, J. B. & Eames, I. Dynamics of monopolar vortices on a topographic beta-plane. J. Fluid Mech. 456, 353–376 (2002).

    Article  Google Scholar 

  14. 14.

    Fletcher, L. N. et al. Temperature and composition of Saturn’s polar hot spots and hexagon. Science 319, 79–81 (2008).

    Article  Google Scholar 

  15. 15.

    Barbosa Aguiar, A. C., Read, P. L., Wordsworth, R. D., Salter, T. & Yamazaki, Y. H. A laboratory model of Saturn’s North Polar Hexagon. Icarus 206, 755–763 (2010).

    Article  Google Scholar 

  16. 16.

    LeBeau, R. P. & Dowling, T. E. EPIC simulations of time-dependent, three-dimensional vortices with application to Neptune’s Great Dark Spot. Icarus 132, 239–265 (1998).

    Article  Google Scholar 

  17. 17.

    Afanasyev, Y. D., Rhines, P. B. & Lindahl, E. G. Velocity and potential vorticity fields measured by altimetric imaging velocimetry in the rotating fluid. Exp. Fluids 47, 913–926 (2009).

    Article  Google Scholar 

  18. 18.

    Román, F. L., Faro, J. & Velasco, S. A simple experiment for measuring the surface tension of soap solutions. Am. J. Phys. 69, 920–921 (2001).

    Article  Google Scholar 

  19. 19.

    Fincham, A. & Spedding, G. Low cost, high resolution DPIV for measurement of turbulent fluid flow. Exps. Fluids 23, 449–462 (1997).

    Article  Google Scholar 

  20. 20.

    Pawlak, G. & Armi, L. Vortex dynamics in a spatially accelerating shear layer. J. Fluid Mech. 376, 1–35 (1998).

    Article  Google Scholar 

  21. 21.

    Kestin, J., Sokolov, M. & Wakeham, W. A. Viscosity of liquid water in the range –8 ºC to 150 ºC. J. Phys. Chem. Ref. Data 7, 941–948 (1978).

    Article  Google Scholar 

  22. 22.

    King, E. M., Stellmach, S. & Aurnou, J. M. Heat transfer by rapidly rotating Rayleigh-Bénard convection. J. Fluid Mech. 691, 568–582 (2012).

    Article  Google Scholar 

  23. 23.

    Marshall, J., Adcroft, A., Hill, C., Perelman, L. & Heisey, C. A finite-volume, incompressible Navier Stokes model for studies of the ocean on parallel computers. J. Geophys. Res. 102, 5753–5766 (1997).

    Article  Google Scholar 

  24. 24.

    Marshall, J., Hill, C., Perelman, L. & Adcroft, A. Hydrostatic, quasi-hydrostatic, and nonhydrostatic ocean modeling. J. Geophys. Res. 102, 5733–5752 (1997).

    Article  Google Scholar 

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Acknowledgements

This research was supported by the Natural Sciences and Engineering Research Council of Canada.

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Y.D.A. designed the experiment, analysed data, developed the theory, performed numerical simulations and wrote the manuscript. Y.Z. performed the experiment, processed and analysed data and contributed to the manuscript.

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Correspondence to Y. D. Afanasyev.

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The authors declare no competing interests.

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Afanasyev, Y.D., Zhang, Y. Cyclonic circulation of Saturn’s atmosphere due to tilted convection. Nature Geosci 11, 164–167 (2018). https://doi.org/10.1038/s41561-018-0070-3

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