Observations of Layering under a Warm-Core Ring in the Gulf of Mexico

Thomas Meunier Physical Oceanography Department, Centro de Investigación Científica y de Educación Superior de Ensenada, Ensenada, Baja California, Mexico

Search for other papers by Thomas Meunier in
Current site
Google Scholar
PubMed
Close
,
Enric Pallàs Sanz Physical Oceanography Department, Centro de Investigación Científica y de Educación Superior de Ensenada, Ensenada, Baja California, Mexico

Search for other papers by Enric Pallàs Sanz in
Current site
Google Scholar
PubMed
Close
,
Miguel Tenreiro Physical Oceanography Department, Centro de Investigación Científica y de Educación Superior de Ensenada, Ensenada, Baja California, Mexico

Search for other papers by Miguel Tenreiro in
Current site
Google Scholar
PubMed
Close
,
José Ochoa Physical Oceanography Department, Centro de Investigación Científica y de Educación Superior de Ensenada, Ensenada, Baja California, Mexico

Search for other papers by José Ochoa in
Current site
Google Scholar
PubMed
Close
,
Angel Ruiz Angulo Icelandic Meteorological Office, Reykjavík, Iceland

Search for other papers by Angel Ruiz Angulo in
Current site
Google Scholar
PubMed
Close
, and
Christian Buckingham Laboratoire d’Océanographie Physique et Spatiale, Institut Universitaire Européen de la Mer, Plouzané, France

Search for other papers by Christian Buckingham in
Current site
Google Scholar
PubMed
Close
Restricted access

Abstract

Two glider transects in the Gulf of Mexico reveal fine-vertical-scale thermohaline structures within a Loop Current eddy (LCE). Partially compensating temperature and salinity anomalies are shown to organize as thin layers below the eddy and near its edges. The anomalies have vertical scales ranging from 2 to 60 m and extend laterally over distances up to 120 km. These structures are evident in synthetic acoustic reflectivity derived from the glider data and are reminiscent of the intense layering observed in seismic imagery around meddies, Agulhas rings, and warm-core Kuroshio rings. The observed layers are aligned with the geostrophic streamfunction rather than isopycnals and develop preferentially in zones of intense vertical shear. These observations suggest that tracer stirring by the eddy’s vertically sheared azimuthal flow might be an important process for their generation. In an attempt to rationalize this process, high-resolution quasigeostrophic simulations were performed using an idealized anticyclonic ring for the initial conditions. As the vortex destabilizes, layering rapidly develops in the model, resulting in structures similar to those found in the observation data. Passive tracer experiments also suggest that the layers form through differential advection of the tracer field by the vertically sheared flow associated with the LCE.

© 2019 American Meteorological Society. For information regarding reuse of this content and general copyright information, consult the AMS Copyright Policy (www.ametsoc.org/PUBSReuseLicenses).

Corresponding author: Thomas Meunier, meunier@cicese.mx

This article is included in the In Honor of Bach-Lien Hua: Ocean Scale Interactions special collection.

Abstract

Two glider transects in the Gulf of Mexico reveal fine-vertical-scale thermohaline structures within a Loop Current eddy (LCE). Partially compensating temperature and salinity anomalies are shown to organize as thin layers below the eddy and near its edges. The anomalies have vertical scales ranging from 2 to 60 m and extend laterally over distances up to 120 km. These structures are evident in synthetic acoustic reflectivity derived from the glider data and are reminiscent of the intense layering observed in seismic imagery around meddies, Agulhas rings, and warm-core Kuroshio rings. The observed layers are aligned with the geostrophic streamfunction rather than isopycnals and develop preferentially in zones of intense vertical shear. These observations suggest that tracer stirring by the eddy’s vertically sheared azimuthal flow might be an important process for their generation. In an attempt to rationalize this process, high-resolution quasigeostrophic simulations were performed using an idealized anticyclonic ring for the initial conditions. As the vortex destabilizes, layering rapidly develops in the model, resulting in structures similar to those found in the observation data. Passive tracer experiments also suggest that the layers form through differential advection of the tracer field by the vertically sheared flow associated with the LCE.

© 2019 American Meteorological Society. For information regarding reuse of this content and general copyright information, consult the AMS Copyright Policy (www.ametsoc.org/PUBSReuseLicenses).

Corresponding author: Thomas Meunier, meunier@cicese.mx

This article is included in the In Honor of Bach-Lien Hua: Ocean Scale Interactions special collection.

Save
  • Alford, M. H., J. A. MacKinnon, H. L. Simmons, and J. D. Nash, 2016: Near-inertial internal gravity waves in the ocean. Annu. Rev. Mar. Sci., 8, 95123, https://doi.org/10.1146/annurev-marine-010814-015746.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Armi, L., D. Hebert, N. Oakey, J. F. Price, P. L. Richardson, H. Thomas Rossby, and B. Ruddick, 1989: Two years in the life of a Mediterranean salt lens. J. Phys. Oceanogr., 19, 354370, https://doi.org/10.1175/1520-0485(1989)019<0354:TYITLO>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Austin, G. B., 1955: Some recent oceanographic surveys of the Gulf of Mexico. Eos, Trans. Amer. Geophys. Union, 36, 885892, https://doi.org/10.1029/TR036i005p00885.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Biescas, B., V. Sallarès, J. L. Pelegrí, F. Machín, R. Carbonell, G. Buffett, J. J. Dañobeitia, and A. Calahorrano, 2008: Imaging meddy finestructure using multichannel seismic reflection data. Geophys. Res. Lett., 35, L11609, https://doi.org/10.1029/2008GL033971.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Biggs, D. C., and F. E. Müller-Karger, 1994: Ship and satellite observations of chlorophyll stocks in interacting cyclone-anticyclone eddy pairs in the western Gulf of Mexico. J. Geophys. Res., 99, 73717384, https://doi.org/10.1029/93JC02153.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Brannigan, L., D. P. Marshall, A. C. Naveira Garabato, A. J. G. Nurser, and J. Kaiser, 2017: Submesoscale instabilities in mesoscale eddies. J. Phys. Oceanogr., 47, 30613085, https://doi.org/10.1175/JPO-D-16-0178.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Cooper, C., G. Z. Forristall, and T. M. Joyce, 1990: Velocity and hydrographic structure of two Gulf of Mexico warm-core rings. J. Geophys. Res., 95, 16631679, https://doi.org/10.1029/JC095iC02p01663.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • D’Asaro, E. A., 2014: Turbulence in the upper-ocean mixed layer. Annu. Rev. Mar. Sci., 6, 101115, https://doi.org/10.1146/annurev-marine-010213-135138.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Damien, P., O. Pasqueron de Fommervault, J. Sheinbaum, J. Jouanno, V. F. Camacho-Ibar, and O. Duteil, 2018: Partitioning of the open waters of the Gulf of Mexico based on the seasonal and interannual variability of chlorophyll concentration. J. Geophys. Res. Oceans, https://doi.org/10.1002/2017JC013456.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Dewar, W. K., 1987: Ventilating warm rings: Theory and energetics. J. Phys. Oceanogr., 17, 22192231, https://doi.org/10.1175/1520-0485(1987)017<2219:VWRTAE>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Dewar, W. K., 1988: Ventilating warm rings: Structure and model evaluation. J. Phys. Oceanogr., 18, 552564, https://doi.org/10.1175/1520-0485(1988)018<0552:VWRSAM>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Dickinson, A., N. J. White, and C.-P. Caulfield, 2017: Spatial variation of diapycnal diffusivity estimated from seismic imaging of internal wave field, Gulf of Mexico. J. Geophys. Res. Oceans, 122, 98279854, https://doi.org/10.1002/2017JC013352.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Elliott, B. A., 1982: Anticyclonic rings in the Gulf of Mexico. J. Phys. Oceanogr., 12, 12921309, https://doi.org/10.1175/1520-0485(1982)012<1292:ARITGO>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Ferrari, R., and K. L. Polzin, 2005: Finescale structure of the T S Relation in the Eastern North Atlantic. J. Phys. Oceanogr., 35, 1437, https://doi.org/10.1175/JPO2763.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Flament, P., 2002: A state variable for characterizing water masses and their diffusive stability: spiciness. Prog. Oceanogr., 54, 493501, https://doi.org/10.1016/S0079-6611(02)00065-4.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Forristall, G. Z., K. J. Schaudt, and C. K. Cooper, 1992: Evolution and kinematics of a loop current eddy in the Gulf of Mexico during 1985. J. Geophys. Res., 97, 21732184, https://doi.org/10.1029/91JC02905.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Garau, B., S. Ruiz, W. G. Zhang, A. Pascual, E. Heslop, J. Kerfoot, and J. Tintoré, 2011: Thermal lag correction on slocum CTD glider data. J. Atmos. Oceanic Technol., 28, 10651071, https://doi.org/10.1175/JTECH-D-10-05030.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Gilbert, A. D., 1988: Spiral structures and spectra in two-dimensional turbulence. J. Fluid Mech., 193, 475497, https://doi.org/10.1017/S0022112088002228.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Hamilton, P., R. Leben, A. Bower, H. Furey, and P. Pérez-Brunius, 2018: Hydrography of the Gulf of Mexico using autonomous floats. J. Phys. Oceanogr., 48, 773794, https://doi.org/10.1175/JPO-D-17-0205.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Haynes, P. H., 2001: Vertical shear plus horizontal stretching as a route to mixing. From Stirring to Mixing in a Stratified Ocean: Proc. 12th ‘Aha Huliko‘a Hawaiian Winter Workshop, Honolulu, HI, University of Hawai‘i at Mānoa, 73–79, http://www.soest.hawaii.edu/PubServices/2001pdfs/Haynes.pdf.

  • Haynes, P. H., and J. Anglade, 1997: The vertical-scale cascade in atmospheric tracers due to large-scale differential advection. J. Atmos. Sci., 54, 11211136, https://doi.org/10.1175/1520-0469(1997)054<1121:TVSCIA>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Hernández-Guerra, A., and T. M. Joyce, 2000: Water masses and circulation in the surface layers of the Caribbean at 66°W. Geophys. Res. Lett., 27, 34973500, https://doi.org/10.1029/1999GL011230.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Hua, B. L., and D. B. Haidvogel, 1986: Numerical simulations of the vertical structure of quasi-geostrophic turbulence. J. Atmos. Sci., 43, 29232936, https://doi.org/10.1175/1520-0469(1986)043<2923:NSOTVS>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Hua, B. L., C. Ménesguen, S. Le Gentil, R. Schopp, B. Marsset, and H. Aiki, 2013: Layering and turbulence surrounding an anticyclonic oceanic vortex: In situ observations and quasi-geostrophic numerical simulations. J. Fluid Mech., 731, 418442, https://doi.org/10.1017/jfm.2013.369.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Joyce, T. M., J. M. Toole, P. Klein, and L. N. Thomas, 2013: A near-inertial mode observed within a Gulf Stream warm-core ring. J. Geophys. Res. Oceans, 118, 17971806, https://doi.org/10.1002/jgrc.20141.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Krahmann, G., C. Papenberg, P. Brandt, and M. Vogt, 2009: Evaluation of seismic reflector slopes with a Yoyo-CTD. Geophys. Res. Lett., 36, L00D02, https://doi.org/10.1029/2009GL038964.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Leben, R. R., 2005: Altimeter-derived loop current metrics. Circulation in the Gulf of Mexico: Observations and Models, Geophys. Monogr., Vol. 161, Amer. Geophys. Union, 181–201, https://doi.org/10.1029/161GM15.

    • Crossref
    • Export Citation
  • Ledwell, J. R., R. He, Z. Xue, S. F. DiMarco, L. J. Spencer, and P. Chapman, 2016: Dispersion of a tracer in the deep Gulf of Mexico. J. Geophys. Res. Oceans, 121, 11101132, https://doi.org/10.1002/2015JC011405.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Leipper, D. F., 1970: A sequence of current patterns in the Gulf of Mexico. J. Geophys. Res., 75, 637657, https://doi.org/10.1029/JC075i003p00637.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Lipphardt, B., A. Poje, A. Kirwan, L. Kantha, and M. Zweng, 2008: Death of three loop current rings. J. Mar. Res., 66, 2560, https://doi.org/10.1357/002224008784815748.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Lueck, R. G., 1990: Thermal inertia of conductivity cells: Theory. J. Atmos. Oceanic Technol., 7, 741755, https://doi.org/10.1175/1520-0426(1990)007<0741:TIOCCT>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Lueck, R. G., and T. Osborn, 1986: The dissipation of kinetic energy in a warm-core ring. J. Geophys. Res., 91, 803818, https://doi.org/10.1029/JC091iC01p00803.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Ménesguen, C., B. L. Hua, X. Carton, F. Klingelhoefer, P. Schnürle, and C. Reichert, 2012: Arms winding around a meddy seen in seismic reflection data close to the Morocco coastline. Geophys. Res. Lett., 39, L05604, https://doi.org/10.1029/2011GL050798.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Ménesguen, C., S. Le Gentil, P. Marchesiello, and N. Ducousso, 2018: Destabilization of an oceanic meddy-like vortex: Energy transfers and significance of numerical settings. J. Phys. Oceanogr., 48, 11511168, https://doi.org/10.1175/jpo-d-17-0126.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Meunier, T., C. Ménesguen, R. Schopp, and S. Le Gentil, 2015: Tracer stirring around a meddy: The formation of layering. J. Phys. Oceanogr., 45, 407423, https://doi.org/10.1175/JPO-D-14-0061.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Meunier, T., C. Ménesguen, X. Carton, S. Le Gentil, and R. Schopp, 2018a: Optimal perturbations of an oceanic vortex lens. Fluids, 3, 63, https://doi.org/10.3390/fluids3030063.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Meunier, T., E. Pallás-Sanz, M. Tenreiro, E. Portela, J. Ochoa, A. Ruiz-Angulo, and S. Cusí, 2018b: The vertical structure of a loop current eddy. J. Geophys. Res. Oceans, 123, 60706090, https://doi.org/10.1029/2018JC013801.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Meunier, T., and Coauthors, 2018c: Intrathermocline eddies embedded within an anticyclonic vortex ring. Geophys. Res. Lett., 45, 76247633, https://doi.org/10.1029/2018GL077527.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Muller-Karger, F. E., and Coauthors, 2015: Natural variability of surface oceanographic conditions in the offshore Gulf of Mexico. Prog. Oceanogr., 134, 5476, https://doi.org/10.1016/j.pocean.2014.12.007.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Nguyen, H. Y., B. L. Hua, R. Schopp, and X. Carton, 2012: Slow quasigeostrophic unstable modes of a lens vortex in a continuously stratified flow. Geophys. Astrophys. Fluid Dyn., 106, 305319, https://doi.org/10.1080/03091929.2011.620568.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Pallàs-Sanz, E., J. Candela, J. Sheinbaum, and J. Ochoa, 2016: Mooring observations of the near-inertial wave wake of Hurricane Ida (2009). Dyn. Atmos. Oceans, 76, 325344, https://doi.org/10.1016/j.dynatmoce.2016.05.003.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Pinheiro, L. M., H. Song, B. Ruddick, J. Dubert, I. Ambar, K. Mustafa, and R. Bezerra, 2010: Detailed 2-D imaging of the Mediterranean outflow and meddies off W Iberia from multichannel seismic data. J. Mar. Syst., 79, 89100, https://doi.org/10.1016/j.jmarsys.2009.07.004.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Portela, E. B., M. Tenreiro, E. Pallas-Sanz, T. Meunier, A. Ruiz-Angulo, E. Sosa-Gutierrez, and S. Cusi, 2018: Hydrography of the central-western Gulf of Mexico. J. Geophys. Res. Oceans, 123, 51345149, https://doi.org/10.1029/2018JC013813.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Rhines, P. B., and W. R. Young, 1983: How rapidly is a passive scalar mixed within closed streamlines? J. Fluid Mech., 133, 133145, https://doi.org/10.1017/S0022112083001822.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Rice, A. E., J. W. Book, W. T. Wood, and T. Fischer, 2013: Current-eddy interaction in the Agulhas Return Current region from the seismic oceanography perspective. J. Acoust. Soc. Amer., 133, 3314, https://doi.org/10.1121/1.4805515.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Ruddick, B., 1983: A practical indicator of the stability of the water column to double-diffusive activity. Deep-Sea Res., 30A, 11051107, https://doi.org/10.1016/0198-0149(83)90063-8.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Ruddick, B., 1992: Intrusive mixing in a Mediterranean salt lens—Intrusion slopes and dynamical mechanisms. J. Phys. Oceanogr., 22, 12741285, https://doi.org/10.1175/1520-0485(1992)022<1274:IMIAMS>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Ruddick, B., 2018: Seismic oceanography’s failure to flourish: A possible solution. J. Geophys. Res. Oceans, 123, 47, https://doi.org/10.1002/2017JC013736.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Ruddick, B., and A. S. Bennett, 1985: Fine structure and mixing at the edge of a warm core ring. J. Geophys. Res., 90, 89438951, https://doi.org/10.1029/JC090iC05p08943.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Ruddick, B., and D. Hebert, 1988: The mixing of Meddy “Sharon.” Small-Scale Turbulence and Mixing in the Ocean: Proceedings of the 19th International Liege Colloquium on Ocean Hydrodynamics, J. C. J. Nihoul and B. M. Jamart, Eds., Elsevier Oceanography Series, Vol. 46, Elsevier, 249–261.

    • Crossref
    • Export Citation
  • Ruddick, B., and K. Richards, 2003: Oceanic thermohaline intrusions: observations. Prog. Oceanogr., 56, 499527, https://doi.org/10.1016/S0079-6611(03)00028-4.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Rudnick, D. L., G. Gopalakrishnan, and B. D. Cornuelle, 2015: Cyclonic eddies in the Gulf of Mexico: Observations by underwater gliders and simulations by numerical model. J. Phys. Oceanogr., 45, 313326, https://doi.org/10.1175/JPO-D-14-0138.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Sallarès, V., B. Biescas, G. Buffett, R. Carbonell, J. J. Dañobeitia, and J. L. Pelegrí, 2009: Relative contribution of temperature and salinity to ocean acoustic reflectivity. Geophys. Res. Lett., 36, L00D06, https://doi.org/10.1029/2009GL040187.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Schmitt, R. W., R. G. Lueck, and T. M. Joyce, 1986: Fine- and microstructure at the edge of a warm-core ring. Deep-Sea Res., 33A, 16651689, https://doi.org/10.1016/0198-0149(86)90073-7.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Smith, K. S., and R. Ferrari, 2009: The production and dissipation of compensated thermohaline variance by mesoscale stirring. J. Phys. Oceanogr., 39, 2477, https://doi.org/10.1175/2009JPO4103.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Song, H., L. M. Pinheiro, B. Ruddick, and F. C. Teixeira, 2011: Meddy, spiral arms, and mixing mechanisms viewed by seismic imaging in the Tagus Abyssal Plain (SW Iberia). J. Mar. Res., 69, 827842, https://doi.org/10.1357/002224011799849309.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Tokos, K. S., and T. Rossby, 1991: Kinematics and dynamics of a Mediterranean salt lens. J. Phys. Oceanogr., 21, 879892, https://doi.org/10.1175/1520-0485(1991)021<0879:KADOAM>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Turner, J. S., 1980: Buoyancy Effects in Fluids. Cambridge University Press, 382 pp.

  • Vidal, V. M. V., F. V. Vidal, and J. M. Pérez-Molero, 1992: Collision of a loop current anticyclonic ring against the continental shelf slope of the western Gulf of Mexico. J. Geophys. Res., 97, 21552172, https://doi.org/10.1029/91JC00486.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Wüst, G., 1964: Stratification and Circulation in the Antillean–Caribbean Basins. Columbia University Press, 201 pp.

  • Xu, F.-H., Y.-L. Chang, L.-Y. Oey, and P. Hamilton, 2013: Loop current growth and eddy shedding using models and observations: Analyses of the July 2011 eddy-shedding event. J. Phys. Oceanogr., 43, 10151027, https://doi.org/10.1175/JPO-D-12-0138.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Yamashita, M., K. Yokota, Y. Fukao, S. Kodaira, S. Miura, and K. Katsumata, 2011: Seismic reflection imaging of a warm core ring south of Hokkaido. Explor. Geophys., 42, 1824, https://doi.org/10.1071/EG11004.

    • Crossref
    • Search Google Scholar
    • Export Citation
All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 1727 596 29
PDF Downloads 755 252 22