• Abramowitz, M., , and I. A. Stegun, Eds.,. 1970: Handbook of Mathematical Functions. Appl. Math. Series, Vol. 55, Natl. Bur. of Stand., 231–233.

    • Search Google Scholar
    • Export Citation
  • Armi, L., , D. Hebert, , N. Oakey, , J. F. Price, , P. L. Richardson, , H. T. Rossby, , and B. Ruddick, 1989: Two years in the life of a Mediterranean salt lens. J. Phys. Oceanogr, 10 , 354370.

    • Search Google Scholar
    • Export Citation
  • Charney, J. G., , and M. Stern, 1962: On the instability of internal baroclinic jets in a rotating atmosphere. J. Atmos. Sci, 19 , 159172.

    • Search Google Scholar
    • Export Citation
  • Chérubin, L., and Coauthors,. 1997: Descriptive analysis of the hydrology and currents on the Iberian shelf from Gibraltar to Cape Finisterre: Preliminary results from the SEMANE and INTERAFOS experiments. Ann. Hydrogr, 21 , 569.

    • Search Google Scholar
    • Export Citation
  • De Szoeke, R. A., , and D. B. Chelton, 1999: The modification of long planetary waves by homogeneous potential vorticity layers. J. Phys. Oceanogr, 29 , 500511.

    • Search Google Scholar
    • Export Citation
  • Dewar, W. K., 1998: On “too fast” baroclinic planetary waves in the general circulation. J. Phys. Oceanogr, 28 , 17391758.

  • Dewar, W. K., , and G. Flierl, 1987: Some effects of the wind on rings. J. Phys. Oceanogr, 17 , 16531667.

  • Hogg, N., , and H. Stommel, 1990: How currents in the upper thermocline could advect meddies deeper down. Deep-Sea Res, 37 , 613623.

  • Joyce, T. M., , and T. J. McDougall, 1992: Physical structure and temporal evolution of Gulf Stream warm-core ring 82B. Deep-Sea Res, 39 , S19S44.

    • Search Google Scholar
    • Export Citation
  • Kaz'min, A. S., , and G. Sutyrin, 1990: Blocking of the Benguela Current by an isolated anticyclone: Analysis of satellite and shipboard data. Sov. J. Remote Sens, 7 , 986995.

    • Search Google Scholar
    • Export Citation
  • Marshall, J. S., , and B. Parthasarathy, 1993: Tearing of an aligned vortex by a current difference in two-layer quasi-geostrophic flow. J. Fluid Mech, 255 , 157182.

    • Search Google Scholar
    • Export Citation
  • McWilliams, J., 1985: Submesoscale, coherent vortices in the ocean. Rev. Geophys, 23 , 165182.

  • McWilliams, J., , and G. Flierl, 1979: On the evolution of isolated, nonlinear vortices. J. Phys. Oceanogr, 9 , 11551182.

  • Morel, Y., 1995a: The influence of an upper thermocline current on intrathermocline eddies. J. Phys. Oceanogr, 25 , 2351.

  • Morel, Y., 1995b: Etude des déplacements et de la dynamique des tourbillons géophysiques. Application aux Meddies. Thèse de l'Université Joseph Fourier-Grenoble I, 155 pp. [Available from Y. Morel, EPSHOM-CMO, BP 426, 29275 Brest Cedex, France.].

    • Search Google Scholar
    • Export Citation
  • Morel, Y., , and J. C. McWilliams, 1997: Evolution of isolated interior vortices in the ocean. J. Phys. Oceanogr, 27 , 727748.

  • Olson, D. B., 1980: The physical oceanography of two rings observed by the cyclonic ring experiment. Part II: Dynamics. J. Phys. Oceanogr, 10 , 514528.

    • Search Google Scholar
    • Export Citation
  • Olson, D. B., 1991: Rings in the ocean. Annu. Rev. Earth Planet Sci, 19 , 283311.

  • Olson, D. B., , and R. H. Evans, 1986: Rings of the Agulhas. Deep-Sea Res, 33 , 2742.

  • Paillet, J., , B. Le Cann, , A. Serpette, , Y. Morel, , and X. Carton, 1999:: Real-time tracking of a Galician Meddy. Geophys. Res. Lett, 26 , 18771880.

    • Search Google Scholar
    • Export Citation
  • Pedlosky, J., 1987: Geophysical Fluid Dynamics. Springer, 710 pp.

  • Pingree, R. D., , and B. Le Cann, 1992: Anticyclonic eddy X91 in the southern bay of Biscay, May 1991 to February 1992. J. Geophys. Res, 97 , 14 35314 367.

    • Search Google Scholar
    • Export Citation
  • Pingree, R. D., , and B. Le Cann, 1993a: Structure of a meddy (Bobby 92) southeast of the Azores. Deep-Sea Res, 40 , 20772103.

  • Pingree, R. D., , and B. Le Cann, 1993b: A shallow meddy (a smeddy) from the secondary Mediterranean salinity maximum. J. Geophys. Res, 98 , 20 16920 185.

    • Search Google Scholar
    • Export Citation
  • Pingree, R. D., , and B. Le Cann, 1994: Winter warming in the southern bay of Biscay and Lagrangian eddy kinematics from a deep-drogued argos buoy. J. Mar. Biol, 74 , 107128.

    • Search Google Scholar
    • Export Citation
  • Reznik, G. M., , and W. K. Dewar, 1994: An analytic theory of distributed axisymmetric barotropic vortices on the β-plane. J. Fluid Mech, 269 , 301321.

    • Search Google Scholar
    • Export Citation
  • Richardson, P., , D. Walsh, , L. Armi, , M. Schröder, , and J. F. Price, 1989:: Tracking three Meddies with SOFAR floats. J. Phys. Oceanogr, 19 , 371383.

    • Search Google Scholar
    • Export Citation
  • Sutyrin, G. G., 1987: The beta-effect and the evolution of a localized vortex. Sov. Phys. Dokl, 32 , 791793.

  • Sutyrin, G. G., , and G. R. Flierl, 1994: Intense vortex motion on the beta-plane: Development of the beta gyres. J. Atmos. Sci.,, 51 , 773790.

    • Search Google Scholar
    • Export Citation
  • Sutyrin, G. G., , and Y. G. Morel, 1997: Intense vortex motion in a stratified fluid on the beta-plane. An analytical model and its validation. J. Fluid Mech, 336 , 203220.

    • Search Google Scholar
    • Export Citation
  • van Ballegooyen, R. C., , M. L. Grüdlingh, , and J. R. E. Lutjeharms, 1994: Eddy fluxes of heat and salt from the southwest Indian Ocean into the southeast Atlantic Ocean: A case study. J. Geophys. Res, 99 , 14 05314 070.

    • Search Google Scholar
    • Export Citation
  • Vandermeirsch, F., 1999: Interaction entre un jet et un tourbillon océanique. Application au courant des Açores et aux Meddies de la campagne SEMAPHORE. Thèse de l'Université de Bretagne Occidentale, 210 pp. [Available from F. Vandermeirsch, EPSHOM-CMO, BP 426, 29275 Brest Cedex, France.].

    • Search Google Scholar
    • Export Citation
All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 120 120 3
PDF Downloads 6 6 0

The Net Advective Effect of a Vertically Sheared Current on a Coherent Vortex

View More View Less
  • 1 Service Hydrographique et Océanographique de la Marine, Centre Militaire d'Océanographie, Brest, France
  • | 2 Graduate School of Oceanography, University of Rhode Island, Narragansett, Rhode Island
© Get Permissions Rent on DeepDyve
Restricted access

Abstract

The nonlinear interaction of a localized vortex with a vertically sheared mean flow has been studied using numerical and asymptotic methods in a multilayer quasigeostrophic model on the beta plane.

Numerical solutions indicate that baroclinic large-scale flows have a weak influence on the translation of coherent vortices, even when the advective effect of the mean flow is important. This is opposed to what is observed in general for the dynamics of linear Rossby waves, which are sensitive to the presence of a baroclinic current. Thus, the nonlinear nature of vortices has to be taken into account to explain this reduction of the net advective effect of a vertically sheared current on a coherent vortex.

The asymptotic method of Sutyrin and Morel is generalized to describe analytically the development of the beta gyres and corresponding vortex motion in the presence of a vertically sheared current. The initial vortex structure is prescribed as a piecewise constant potential vorticity anomaly in one or two layers with no motion in the lower layer. Three major effects are shown to contribute to the vortex translation: advection by the mean current, beta-gyre development due to planetary and mean flow potential vorticity gradients, and deformation of the vortex core. The analytical model predicts that the initial uniform gradient associated with the background current is strongly distorted and eventually “homogenized,” leading to the cancellation of the current net advective effect. In other words, the part of beta gyres associated with the mean-flow potential vorticity gradient compensates most of the advection by the baroclinic part of the current. Thus, the vortex is advected mainly by the planetary beta gyres (and the barotropic part of the flow if any).

The influence of the vortex size and strength on this compensation mechanism is evaluated.

Corresponding author address: Dr. Yves Morel, Service Hydrographique et Océanographie de la Marine (EPSHOM-CMO), Centre Militaire d'Océanographie, B.P. 426, 29275 Brest Cedex, France. Email: morel@shom.fr

Abstract

The nonlinear interaction of a localized vortex with a vertically sheared mean flow has been studied using numerical and asymptotic methods in a multilayer quasigeostrophic model on the beta plane.

Numerical solutions indicate that baroclinic large-scale flows have a weak influence on the translation of coherent vortices, even when the advective effect of the mean flow is important. This is opposed to what is observed in general for the dynamics of linear Rossby waves, which are sensitive to the presence of a baroclinic current. Thus, the nonlinear nature of vortices has to be taken into account to explain this reduction of the net advective effect of a vertically sheared current on a coherent vortex.

The asymptotic method of Sutyrin and Morel is generalized to describe analytically the development of the beta gyres and corresponding vortex motion in the presence of a vertically sheared current. The initial vortex structure is prescribed as a piecewise constant potential vorticity anomaly in one or two layers with no motion in the lower layer. Three major effects are shown to contribute to the vortex translation: advection by the mean current, beta-gyre development due to planetary and mean flow potential vorticity gradients, and deformation of the vortex core. The analytical model predicts that the initial uniform gradient associated with the background current is strongly distorted and eventually “homogenized,” leading to the cancellation of the current net advective effect. In other words, the part of beta gyres associated with the mean-flow potential vorticity gradient compensates most of the advection by the baroclinic part of the current. Thus, the vortex is advected mainly by the planetary beta gyres (and the barotropic part of the flow if any).

The influence of the vortex size and strength on this compensation mechanism is evaluated.

Corresponding author address: Dr. Yves Morel, Service Hydrographique et Océanographie de la Marine (EPSHOM-CMO), Centre Militaire d'Océanographie, B.P. 426, 29275 Brest Cedex, France. Email: morel@shom.fr

Save