PRELIMINARY RESULTS OF LABORATORY INVESTIGATIONS OF THE EVOLUTION OF NON-FRONTAL EDDIES IN A TWO-LAYERED ROTATING FLUID

Authors

  • A. G. Zatsepin Shirshov Institute of Oceanology, Russian Academy of Sciences; Moscow Institute of Physics and Technology
  • D. N. Elkin Shirshov Institute of Oceanology, Russian Academy of Sciences
  • D. R. Shvartsman Moscow Institute of Physics and Technology

DOI:

https://doi.org/10.29006/1564-2291.JOR-2023.51(1).1

Keywords:

Open ocean eddies, laboratory modeling, two-layer stratified rotating fluid, baroclinic instability, viscous degeneration viscous, smooth, rough, sloping bottom

Abstract

In this work, by means of laboratory modeling, the patterns of evolution (baroclinic instability and/or viscous degeneration) of mesoscale non-frontal baroclinic eddies, or open ocean eddies (without a core with the water of different density) were revealed. The experiment was provided in a two-layer salinity-stratified aquatic environment in a cylindrical tank located on a rotating platform. Using the original application of the “cylinder method”, single axisymmetric cyclonic and anticyclonic eddies were produced in the upper layer, and their evolution was traced over 100 or more platform rotation periods (laboratory days). It has been established that the vortices lose their stability if the value of the defining parameter representing the ratio of the Burger and Froude numbers is less than the critical one. In this case, eddies either fall apart into two or more secondary vortices (strong instability) or acquire an elongated shape (weak instability). The slope of the bottom and its roughness increase the stability of eddies. For values of the determining parameter greater than the critical one, the vortices are stable and gradually degenerate due to viscous friction. In the case of a large difference in salinity (density) between the layers, the bottom roughness does not have a significant effect on the rate of upper layer eddy damping, which, apparently, is determined by the friction in this layer. A parametrization is proposed that describes the exponential law of eddy decay, which is tested on the example of the Black Sea mesoscale eddy.

References


  1. Blatov, A. S., N. P. Bulgakov, and V. A. Ivanov et al., 1984: Hydrophysical fields variability in the Black Sea. Leningrad, Gidrometeoizdat, 240 p.

  2. Dikarev, S. N., 1983: Influence of rotation on convection structure in deep homogenous fluid. Dokl. Akad. Nauk SSSR, 283 (3), 718–720.

  3. Elkin, D. N. and A. G. Zatsepin, 2014: Laboratory study of a shear instability of an Alongshore sea current. Oceanology, 54 (5), 576–582.

  4. Fedorov, K. N., 1983: The Physical Nature and Structure of Oceanic Fronts. Springer-Verlag, 333 p.

  5. Greenspan, H. P., 1975: The Theory of Rotating Fluids. Leningrad, Gidrometeoizdat, 304 p.

  6. Griffiths, R. W. and P. F. Linden, 1981: The stability of vorticies in a rotating stratified fluid. J. Fluid Mech., 105, 283–316.

  7. Griffiths, R. W. and E. J. Hopfinger, 1984: The Structure of Mesoscale Turbulence and Horizontal Spreading at Ocean Fronts. Deep Sea Research. Part A. Oceanographic Research Papers, 31 (3), 245–269, https://doi.org/10.1016/0198-0149(84)90104-3.

  8. Kamenkovich, V. M., M. N. Koshlyakov, and A. S. Monin, 1982: Mesoscale eddies in the ocean. Leningrad, Gidrometeoizdat, 264 p.

  9. Kloosterziel, R. C. and G. J. F. van Heijst, 1991: An experimental study of unstable barotropiс vorties in a rotating fluid. J. Fluid Mech., 223, 1–24.

  10. Koshlyakov, M. N. and V. N. Belokopytov, 2020: Mesoscale eddies in the open ocean: review of experimental investigations. Physical oceanography, 27 (6), 559–572.

  11. Kubryakov, A. A. and S. V. Stanichny, 2015: Mesoscale eddies in the Black sea from satellite altimetry data. Oceanology, 55 (5), 56–67.

  12. Saunders, P. M., 1973: The Instability of a Baroclinic Vortex. J. Phys. Oceanogr., 3 (1), 61–65.

  13. Zatsepin, A. G., 1983: Some experiments on rotating baroclinic vorvices. Tech. Report. WHOI-83-41, 272–285.

  14. Zatsepin, A. G. and A. G. Kostianoy, 1992: Laboratory studies of the instability of baroclinic vortices and fronts. Coherent structures and self-organization of ocean motions. Moscow, Nauka, 163–176.

  15. Zatsepin, A. G., A. A. Kubryakov, A. A. Aleskerova, D. N. Elkin, and O. N. Kukleva, 2019: Physical mechanisms of submesoscale eddies generation: evidences from laboratory modeling and satellite data in the Black Sea. Ocean dynamics, 69 (2), 253–266, https://doi.org/10.1007/s10236-018-1239-4.

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Published

2023-04-10

Issue

Vol. 51 No. 1 (2023): Journal of Oceanological Research

Section

Ocean physics and climate

License

Transfer of copyrights occurs on the basis of a license agreement between the Author and Shirshov Institute of Oceanology, RAS

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