• Bane, J., Jr., and W. Dewar, 1988: Gulf Stream bimodality and variability downstream of the Charleston Bump. J. Geophys. Res., 93, 66956710, doi:10.1029/JC093iC06p06695.

    • Search Google Scholar
    • Export Citation
  • Bane, J., Jr., D. Brooks, and K. Lorenson, 1981: Synoptic observations of the three-dimensional structure and propagation of Gulf Stream meanders along the Carolina continental margin. J. Geophys. Res., 86, 64116425, doi:10.1029/JC086iC07p06411.

    • Search Google Scholar
    • Export Citation
  • Blanton, J., L. Atkinson, L. Pietrafesa, and T. Lee, 1981: The intrusion of Gulf Stream water across the continental shelf due to topographically-induced upwelling. Deep-Sea Res., 28, 393405, doi:10.1016/0198-0149(81)90006-6.

    • Search Google Scholar
    • Export Citation
  • Boccaletti, G., R. Ferrari, and B. Fox-Kemper, 2007: Mixed layer instabilities and restratification. J. Phys. Oceanogr., 37, 22282250, doi:10.1175/JPO3101.1.

    • Search Google Scholar
    • Export Citation
  • Bower, A. S., 1989: Potential vorticity balances and horizontal divergence along particle trajectories in Gulf Stream meanders east of Cape Hatteras. J. Phys. Oceanogr., 19, 16691681, doi:10.1175/1520-0485(1989)019<1669:PVBAHD>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Bracco, A., and J. Pedlosky, 2003: Vortex generation by topography in locally unstable baroclinic flows. J. Phys. Oceanogr., 33, 207219, doi:10.1175/1520-0485(2003)033<0207:VGBTIL>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Brooks, D., and J. Bane Jr., 1981: Gulf Stream fluctuations and meanders over the Onslow Bay upper continental slope. J. Phys. Oceanogr., 11, 247256, doi:10.1175/1520-0485(1981)011<0247:GSFAMO>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Brooks, D., and J. Bane Jr., 1983: Gulf Stream meanders off North Carolina during winter and summer 1979. J. Geophys. Res., 88, 46334650, doi:10.1029/JC088iC08p04633.

    • Search Google Scholar
    • Export Citation
  • Carton, J., and B. Giese, 2008: A reanalysis of ocean climate using Simple Ocean Data Assimilation (SODA). Mon. Wea. Rev., 136, 29993017, doi:10.1175/2007MWR1978.1.

    • Search Google Scholar
    • Export Citation
  • Danioux, E., J. Vanneste, P. Klein, and H. Sasaki, 2012: Spontaneous inertia-gravity-wave generation by surface-intensified turbulence. J. Fluid Mech., 699, 153173, doi:10.1017/jfm.2012.90.

    • Search Google Scholar
    • Export Citation
  • Dewar, W., and J. Bane Jr., 1985: Subsurface energetics of the Gulf Stream near the Charleston Bump. J. Phys. Oceanogr., 15, 17711789, doi:10.1175/1520-0485(1985)015<1771:SEOTGS>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Dritschel, D., P. Haynes, M. Juckes, and T. Shepherd, 1991: The stability of a two-dimensional vorticity filament under uniform strain. J. Fluid Mech., 230, 647665, doi:10.1017/S0022112091000915.

    • Search Google Scholar
    • Export Citation
  • Glenn, S., and C. Ebbesmeyer, 1994: The structure and propagation of a Gulf Stream frontal eddy along the North Carolina shelf break. J. Geophys. Res., 99, 50295046, doi:10.1029/93JC02786.

    • Search Google Scholar
    • Export Citation
  • Govoni, J., J. Hare, and E. Davenport, 2013: The distribution of larval fishes of the Charleston Gyre region off the southeastern United States in winter shaped by mesoscale, cyclonic eddies. Mar. Coastal Fish., 5, 246259, doi:10.1080/19425120.2013.820245.

    • Search Google Scholar
    • Export Citation
  • Gula, J., M. Molemaker, and J. McWilliams, 2014: Submesoscale cold filaments in the Gulf Stream. J. Phys. Oceanogr., 44, 26172643, doi:10.1175/JPO-D-14-0029.1.

    • Search Google Scholar
    • Export Citation
  • Gula, J., M. Molemaker, and J. McWilliams, 2015a: Gulf Stream dynamics along the southeastern U.S. seaboard. J. Phys. Oceanogr., 45, 690715, doi:10.1175/JPO-D-14-0154.1.

    • Search Google Scholar
    • Export Citation
  • Gula, J., M. Molemaker, and J. McWilliams, 2015b: Topographic vorticity generation, submesoscale instability and vortex street formation in the Gulf Stream. Geophys. Res. Lett., 42, 40544062, doi:10.1002/2015GL063731.

    • Search Google Scholar
    • Export Citation
  • Haney, J., 1986: Seabird segregation at Gulf Stream frontal eddies. Mar. Ecol. Prog. Ser., 28, 279285, doi:10.3354/meps028279.

  • Harrison, D., and A. Robinson, 1978: Energy analysis of open regions of turbulent flows: Mean eddy energetics of a numerical ocean circulation experiment. Dyn. Atmos. Oceans, 2, 185211, doi:10.1016/0377-0265(78)90009-X.

    • Search Google Scholar
    • Export Citation
  • Hoskins, B. J., 1974: The role of potential vorticity in symmetric stability and instability. Quart. J. Roy. Meteor. Soc., 100, 480482, doi:10.1002/qj.49710042520.

    • Search Google Scholar
    • Export Citation
  • Hoskins, B. J., 1982: The mathematical theory of frontogenesis. Annu. Rev. Fluid Mech., 14, 131151, doi:10.1146/annurev.fl.14.010182.001023.

    • Search Google Scholar
    • Export Citation
  • Large, W., J. McWilliams, and S. Doney, 1994: Oceanic vertical mixing: A review and a model with a nonlocal boundary layer parameterization. Rev. Geophys., 32, 363403, doi:10.1029/94RG01872.

    • Search Google Scholar
    • Export Citation
  • Lee, T., and L. Atkinson, 1983: Low-frequency current and temperature variability from Gulf Stream frontal eddies and atmospheric forcing along the southeast U.S. outer continental shelf. J. Geophys. Res., 88, 45414567, doi:10.1029/JC088iC08p04541.

    • Search Google Scholar
    • Export Citation
  • Lee, T., L. Atkinson, and R. Legeckis, 1981: Observations of a Gulf Stream frontal eddy on the Georgia continental shelf, April 1977. Deep-Sea Res., 28, 347378, doi:10.1016/0198-0149(81)90004-2.

    • Search Google Scholar
    • Export Citation
  • Lee, T., J. Yoder, and L. Atkinson, 1991: Gulf Stream frontal eddy influence on productivity of the southeast U.S. continental shelf. J. Geophys. Res., 96, 22 19122 205, doi:10.1029/91JC02450.

    • Search Google Scholar
    • Export Citation
  • Legeckis, R., 1975: Application of synchronous meteorological satellite data to the study of time dependent sea surface temperature changes along the boundary of the Gulf Stream. Geophys. Res. Lett., 2, 435438, doi:10.1029/GL002i010p00435.

    • Search Google Scholar
    • Export Citation
  • Legeckis, R., 1979: Satellite observations of the influence of bottom topography on the seaward deflection of the Gulf Stream off Charleston, South Carolina. J. Phys. Oceanogr., 9, 483497, doi:10.1175/1520-0485(1979)009<0483:SOOTIO>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • McClain, C., and L. Atkinson, 1985: A note on the Charleston Gyre. J. Geophys. Res., 90, 11 85711 861, doi:10.1029/JC090iC06p11857.

  • McClain, C., L. Pietrafesa, and J. Yoder, 1984: Observations of Gulf Stream-induced and wind-driven upwelling in the Georgia Bight using ocean color and infrared imagery. J. Geophys. Res., 89, 37053723, doi:10.1029/JC089iC03p03705.

    • Search Google Scholar
    • Export Citation
  • Molemaker, M., J. McWilliams, and W. Dewar, 2015: Submesoscale instability and generation of mesoscale anticyclones near a separation of the California Undercurrent. J. Phys. Oceanogr., 45, 613629, doi:10.1175/JPO-D-13-0225.1.

    • Search Google Scholar
    • Export Citation
  • Nagai, T., A. Tandon, E. Kunze, and A. Mahadevan, 2015: Spontaneous generation of near-inertial waves by the Kuroshio Front. J. Phys. Oceanogr., 45, 23812406, doi:10.1175/JPO-D-14-0086.1.

    • Search Google Scholar
    • Export Citation
  • Olson, D., O. Brown, and S. Emmerson, 1983: Gulf Stream frontal statistics from Florida Straits to Cape Hatteras derived from satellite and historical data. J. Geophys. Res., 88, 45694577, doi:10.1029/JC088iC08p04569.

    • Search Google Scholar
    • Export Citation
  • Osgood, K., J. Bane Jr., and W. Dewar, 1987: Vertical velocities and dynamical balances in Gulf Stream meanders. J. Geophys. Res., 92, 13 02913 040, doi:10.1029/JC092iC12p13029.

    • Search Google Scholar
    • Export Citation
  • Ramachandran, S., A. Tandon, and A. Mahadevan, 2014: Enhancement in vertical fluxes at a front by mesoscale-submesoscale coupling. J. Geophys. Res. Oceans, 119, 84958511, doi:10.1002/2014JC01021.

    • Search Google Scholar
    • Export Citation
  • Rayleigh, L., 1880: On the stability, or instability of certain fluid motions. Proc. Roy. Soc. London, 9, 5770.

  • Risien, C. M., and D. B. Chelton, 2008: A global climatology of surface wind and wind stress fields from eight years of QuikSCAT scatterometer data. J. Phys. Oceanogr., 38, 23792413, doi:10.1175/2008JPO3881.1.

    • Search Google Scholar
    • Export Citation
  • Savidge, D., and J. Bane Jr., 2004: Gulf Stream meander propagation past Cape Hatteras. J. Phys. Oceanogr., 34, 20732085, doi:10.1175/1520-0485(2004)034<2073:GSMPPC>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Shakespeare, C., and J. Taylor, 2014: The spontaneous generation of inertia-gravity waves during frontogenesis forced by large strain: Theory. J. Fluid Mech., 757, 817853, doi:10.1017/jfm.2014.514.

    • Search Google Scholar
    • Export Citation
  • Shchepetkin, A., and J. McWilliams, 2005: The Regional Oceanic Modeling System (ROMS): A split-explicit, free-surface, topography-following- coordinate ocean model. Ocean Modell., 9, 347404, doi:10.1016/j.ocemod.2004.08.002.

    • Search Google Scholar
    • Export Citation
  • Silva, A. D., C. Young, and S. Levitus, 1994: Algorithms and Procedures. Vol. 1, Atlas of Surface Marine Data 1994, NOAA Atlas NESDIS 6, 74 pp.

  • Thomas, L., and T. Joyce, 2010: Subduction on the northern and southern flanks of the Gulf Stream. J. Phys. Oceanogr., 40, 429438, doi:10.1175/2009JPO4187.1.

    • Search Google Scholar
    • Export Citation
  • von Arx, W. S., D. F. Bumpus, and W. S. Richardson, 1955: On the fine-structure of the Gulf Stream front. Deep-Sea Res., 3, 4665, doi:10.1016/0146-6313(55)90035-6.

    • Search Google Scholar
    • Export Citation
  • Vukovich, F. M., and B. W. Crissman, 1980: Some aspects of Gulf Stream western boundary eddies from satellite and in situ data. J. Phys. Oceanogr., 10, 17921813, doi:10.1175/1520-0485(1980)010<1792:SAOGSW>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Vukovich, F. M., B. W. Crissman, M. Bushnell, and W. King, 1979: Gulf Stream boundary eddies off the east coast of Florida. J. Phys. Oceanogr., 9, 12141223, doi:10.1175/1520-0485(1979)009<1214:GSBEOT>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Wolfe, C., and C. Cenedese, 2006: Laboratory experiments on eddy generation by a buoyant coastal current flowing over variable bathymetry. J. Phys. Oceanogr., 36, 395411, doi:10.1175/JPO2857.1.

    • Search Google Scholar
    • Export Citation
  • Yoder, J., L. Atkinson, T. Lee, H. Kim, and C. McClain, 1981: Role of Gulf Stream frontal eddies in forming phytoplankton patches on the outer southeastern shelf. Limnol. Oceanogr., 26, 11031110, doi:10.4319/lo.1981.26.6.1103.

    • Search Google Scholar
    • Export Citation
  • Yoder, J., L. Atkinson, S. Bishop, J. Blanton, T. Lee, and L. Pietrafesa, 1985: Phytoplankton dynamics within Gulf Stream intrusions on the southeastern United States continental shelf during summer 1981. Cont. Shelf Res., 4, 611635, doi:10.1016/0278-4343(85)90033-0.

    • Search Google Scholar
    • Export Citation
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Submesoscale Dynamics of a Gulf Stream Frontal Eddy in the South Atlantic Bight

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  • 1 Laboratoire de Physique des Océans, Université de Bretagne Occidentale, Brest, France
  • | 2 Department of Atmospheric and Oceanic Sciences, University of California, Los Angeles, Los Angeles, California
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Abstract

Frontal eddies are commonly observed and understood as the product of an instability of the Gulf Stream along the southeastern U.S. seaboard. Here, the authors study the dynamics of a simulated Gulf Stream frontal eddy in the South Atlantic Bight, including its structure, propagation, and emergent submesoscale interior and neighboring substructure, at very high resolution (dx = 150 m). A rich submesoscale structure is revealed inside the frontal eddy. Meander-induced frontogenesis sharpens the gradients and forms very sharp fronts between the eddy and the adjacent Gulf Stream. The strong straining increases the velocity shear and suppresses the development of barotropic instability on the upstream face of the meander trough. Barotropic instability of the sheared flow develops from small-amplitude perturbations when the straining weakens at the trough. Small-scale meandering perturbations evolve into rolled-up submesoscale vortices that are advected back into the interior of the frontal eddy. The deep fronts mix the tracer properties and enhance vertical exchanges of tracers between the mixed layer and the interior, as diagnosed by virtual Lagrangian particles. The frontal eddy also locally creates a strong southward flow against the shelf leading to topographic generation of submesoscale centrifugal instability and mixing. In eddy-resolving models that do not resolve these submesoscale processes, there is a significant weakening of the intensity of the upwelling in the core of the frontal eddies, and their decay is generally too fast.

Corresponding author address: Jonathan Gula, Laboratoire de Physique des Océans, Université de Bretagne Occidentale, 6 Avenue Le Gorgeu, CS 93837, 29238 Brest, France. E-mail: jonathan.gula@univ-brest.fr

Abstract

Frontal eddies are commonly observed and understood as the product of an instability of the Gulf Stream along the southeastern U.S. seaboard. Here, the authors study the dynamics of a simulated Gulf Stream frontal eddy in the South Atlantic Bight, including its structure, propagation, and emergent submesoscale interior and neighboring substructure, at very high resolution (dx = 150 m). A rich submesoscale structure is revealed inside the frontal eddy. Meander-induced frontogenesis sharpens the gradients and forms very sharp fronts between the eddy and the adjacent Gulf Stream. The strong straining increases the velocity shear and suppresses the development of barotropic instability on the upstream face of the meander trough. Barotropic instability of the sheared flow develops from small-amplitude perturbations when the straining weakens at the trough. Small-scale meandering perturbations evolve into rolled-up submesoscale vortices that are advected back into the interior of the frontal eddy. The deep fronts mix the tracer properties and enhance vertical exchanges of tracers between the mixed layer and the interior, as diagnosed by virtual Lagrangian particles. The frontal eddy also locally creates a strong southward flow against the shelf leading to topographic generation of submesoscale centrifugal instability and mixing. In eddy-resolving models that do not resolve these submesoscale processes, there is a significant weakening of the intensity of the upwelling in the core of the frontal eddies, and their decay is generally too fast.

Corresponding author address: Jonathan Gula, Laboratoire de Physique des Océans, Université de Bretagne Occidentale, 6 Avenue Le Gorgeu, CS 93837, 29238 Brest, France. E-mail: jonathan.gula@univ-brest.fr
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