Editorial Type:
Article
Article Type:
Research Article

Asymmetry of an Equilibrated Gulf Stream–Type Jet over Topographic Slope

Sergei A. Frolov Graduate School of Oceanography, University of Rhode Island, Narragansett, Rhode Island

Search for other papers by Sergei A. Frolov in
Current site
Google Scholar
PubMed Close
,
Georgi G. Sutyrin Graduate School of Oceanography, University of Rhode Island, Narragansett, Rhode Island

Search for other papers by Georgi G. Sutyrin in
Current site
Google Scholar
PubMed Close
, and
Isaac Ginis Graduate School of Oceanography, University of Rhode Island, Narragansett, Rhode Island

Search for other papers by Isaac Ginis in
Current site
Google Scholar
PubMed Close
Print Publication:
01 May 2004
DOI:
https://doi.org/10.1175/1520-0485(2004)034<1087:AOAEGS>2.0.CO;2
Page(s):
1087–1102
Restricted access

Abstract

The symmetry properties of the Gulf Stream–type jet equilibrated over topographic slope are investigated in a series of idealized numerical experiments. A baroclinically unstable zonal jet equilibrates over a sloping bottom through the process of potential vorticity (PV) homogenization underneath the main thermocline by the bottom-intensified eddy activity associated with the stream meandering. Potential vorticity homogenization underneath the main thermocline leads to formation of recirculation gyres on both sides of the jet. The magnitude of the northern recirculation gyre, as measured by its westward transport, is larger than the magnitude of the southern recirculation gyre. This asymmetry in recirculations is shown to be the result of an asymmetric PV mixing underneath the thermocline produced by an asymmetric jet. In particular, the lateral shift of the velocity maximum near the surface relative to the velocity maximum at depth is shown to be responsible for the asymmetry. The results are related to the Gulf Stream data between 73° and 65°W.

Corresponding author address: Dr. Isaac Ginis, Graduate School of Oceanography, University of Rhode Island, Narragansett, RI 02882-1197. Email: iginis@gso.uri.edu

Abstract

The symmetry properties of the Gulf Stream–type jet equilibrated over topographic slope are investigated in a series of idealized numerical experiments. A baroclinically unstable zonal jet equilibrates over a sloping bottom through the process of potential vorticity (PV) homogenization underneath the main thermocline by the bottom-intensified eddy activity associated with the stream meandering. Potential vorticity homogenization underneath the main thermocline leads to formation of recirculation gyres on both sides of the jet. The magnitude of the northern recirculation gyre, as measured by its westward transport, is larger than the magnitude of the southern recirculation gyre. This asymmetry in recirculations is shown to be the result of an asymmetric PV mixing underneath the thermocline produced by an asymmetric jet. In particular, the lateral shift of the velocity maximum near the surface relative to the velocity maximum at depth is shown to be responsible for the asymmetry. The results are related to the Gulf Stream data between 73° and 65°W.

Corresponding author address: Dr. Isaac Ginis, Graduate School of Oceanography, University of Rhode Island, Narragansett, RI 02882-1197. Email: iginis@gso.uri.edu

Save
Cover Journal of Physical Oceanography
Journal of Physical Oceanography

  • Blumberg, A., and G. Mellor, 1987: A description of a three-dimensional coastal ocean circulation model. Three-Dimensional Coastal Ocean Models, N. Heaps, Ed., Vol. 4, Amer. Geophys. Union, 1–16.

    • Search Google Scholar
    • Export Citation

  • Boss, E., and L. Thompson, 1999: Mean flow evolution of a baroclinically unstable potential vorticity front. J. Phys. Oceanogr, 29 , 273–287.

    • Search Google Scholar
    • Export Citation

  • Bower, A., and N. Hogg, 1996: Structure of the Gulf Stream and its recirculations at 55°W. J. Phys. Oceanogr, 26 , 1002–1022.

  • Bush, A., J. McWilliams, and W. Pletier, 1995: The formation of the oceanic eddies in symmetric and asymmetric jets. Part I: Early time evolution and bulk eddy transports. J. Phys. Oceanogr, 25 , 273–287.

    • Search Google Scholar
    • Export Citation

  • Eady, E., 1949: Long waves and cyclone waves. Tellus, 1 , 33–52.

  • Halkin, D., and H. Rossby, 1985: The structure and transport of the Gulf Stream at 73°W. J. Phys. Oceanogr, 15 , 1439–1452.

  • Holland, W., and D. Haidvogel, 1980: A parameter study of the mixed instability of idealized ocean currents. Dyn. Atmos. Oceans, 4 , 185–215.

    • Search Google Scholar
    • Export Citation

  • Ikeda, M., 1981: Meanders and detached eddies of a strong eastward-flowing jet using a two-layer quasi-geostrophic model. J. Phys. Oceanogr, 11 , 526–540.

    • Search Google Scholar
    • Export Citation

  • Jayne, S., and N. Hogg, 1999: On recirculation forced by an unstable jet. J. Phys. Oceanogr, 29 , 2711–2718.

  • Jayne, S., N. Hogg, and P. Malanotte-Rizzoli, 1996: Recirculation gyres forced by a beta-plane jet. J. Phys. Oceanogr, 26 , 492–504.

  • Johns, W., T. Shay, J. Bane, and D. Watts, 1995: Gulf Stream structure, transport, and recirculation near 68°W. J. Geophys. Res, 100 , 817–838.

    • Search Google Scholar
    • Export Citation

  • Logoutov, O., G. Sutyrin, and D. Watts, 2001: Potential vorticity structure across the Gulf Stream: Observations and a PV gradient model. J. Phys. Oceanogr, 31 , 637–644.

    • Search Google Scholar
    • Export Citation

  • Mellor, G., 1996: Users guide for a three-dimensional, primitive equation, numerical ocean model. Atmospheric and Oceanic Sciences Program, Princeton University, 35 pp.

    • Search Google Scholar
    • Export Citation

  • Mellor, G., and T. Yamada, 1982: Development of a turbulence closure model for geophysical fluid problems. Rev. Geophys. Space Phys, 20 , 851–875.

    • Search Google Scholar
    • Export Citation

  • Pedlosky, J., 1987: Geophysical Fluid Dynamics, 2d ed. Springer-Verlag, 710 pp.

  • Rhines, P., 1977: The dynamics of unsteady currents. The Sea, E. D. Goldberg, Ed., Marine Modeling, Vol. 6, Wiley and Sons, 189– 318.

  • Robinson, A., J. Luyten, and F. Fuglister, 1974: Transient Gulf Stream meandering. Part I: An observational experiment. J. Phys. Oceanogr, 4 , 237–255.

    • Search Google Scholar
    • Export Citation

  • Savidge, D., and J. Bare, 1999: Cyclogenesis in the deep ocean beneath the Gulf Stream. J. Geophys. Res, 104 , 18111–18126.

  • Smagorinsky, J., 1963: General circulation experiments with primitive equations: I. The basic experiments. Mon. Wea. Rev, 91 , 291–304.

    • Search Google Scholar
    • Export Citation

  • Sutyrin, G., I. Ginis, and S. Frolov, 2001: Equilibration of baroclinic meanders and deep eddies in a Gulf Stream–type jet over a sloping bottom. J. Phys. Oceanogr, 31 , 2049–2065.

    • Search Google Scholar
    • Export Citation

  • Swanson, K., and R. Pierrehumbert, 1994: Nonlinear wave packet evolution on a baroclinically unstable jet. J. Atmos. Sci, 51 , 384–396.

    • Search Google Scholar
    • Export Citation

  • Watts, D., K. Tracey, J. Bane, and T. Shay, 1995: Gulf Stream path and thermocline structure near 74°W and 68°W. J. Geophys. Res, 100 , 18291–18312.

    • Search Google Scholar
    • Export Citation

  • Wood, R., 1988: Unstable waves on oceanic fronts: Large amplitude behavior and mean flow generation. J. Phys. Oceanogr, 18 , 775–787.

  • Wood, R., and M. Ikeda, 1994: Comparison of mesoscale meanders and eddies simulated by quasi-geostrophic and primitive equation models: A case study. J. Geophys. Res, 99 (C11) 22645–22  663.

    • Search Google Scholar
    • Export Citation
All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 355 166 91
PDF Downloads 74 33 1