Editorial Type:
Article
Article Type:
Research Article

Anisotropic Material Transport by Eddies and Eddy-Driven Currents in a Model of the North Atlantic

Igor Kamenkovich Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, Florida

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Pavel Berloff Department of Mathematics, and Grantham Institute for Climate Change, Imperial College London, London, United Kingdom, and Woods Hole Oceanographic Institution, Woods Hole, Massachusetts

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Joseph Pedlosky Woods Hole Oceanographic Institution, Woods Hole, Massachusetts

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Print Publication:
01 Dec 2009
DOI:
https://doi.org/10.1175/2009JPO4239.1
Page(s):
3162–3175
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Abstract

This study analyzes anisotropic properties of the material transport by eddies and eddy-driven zonal jets in a general circulation model of the North Atlantic through the analysis of Lagrangian particle trajectories. Spreading rates—defined here as half the rate of change in the particle dispersion—in the zonal direction systematically exceed the meridional rates by an order of magnitude. Area-averaged values for the upper-ocean zonal and meridional spreading rates are approximately 8100 and 1400 m2 s−1, respectively, and in the deep ocean they are 2400 and 200 m2 s−1. The results demonstrate that this anisotropy is mainly due to the action of the transient eddies and not to the shear dispersion associated with the time-mean jets. This property is consistent with the fact that eddies in this study have zonally elongated shapes. With the exception of the upper-ocean subpolar gyre, eddies also cause the superdiffusive zonal spreading, significant variations in the spreading rate in the vertical and meridional directions, and the difference between the westward and eastward spreading.

Corresponding author address: Igor Kamenkovich, 4600 Rickenbacker Causeway, University of Miami, Miami, FL 33149. Email: ikamenkovich@rsmas.miami.edu

Abstract

This study analyzes anisotropic properties of the material transport by eddies and eddy-driven zonal jets in a general circulation model of the North Atlantic through the analysis of Lagrangian particle trajectories. Spreading rates—defined here as half the rate of change in the particle dispersion—in the zonal direction systematically exceed the meridional rates by an order of magnitude. Area-averaged values for the upper-ocean zonal and meridional spreading rates are approximately 8100 and 1400 m2 s−1, respectively, and in the deep ocean they are 2400 and 200 m2 s−1. The results demonstrate that this anisotropy is mainly due to the action of the transient eddies and not to the shear dispersion associated with the time-mean jets. This property is consistent with the fact that eddies in this study have zonally elongated shapes. With the exception of the upper-ocean subpolar gyre, eddies also cause the superdiffusive zonal spreading, significant variations in the spreading rate in the vertical and meridional directions, and the difference between the westward and eastward spreading.

Corresponding author address: Igor Kamenkovich, 4600 Rickenbacker Causeway, University of Miami, Miami, FL 33149. Email: ikamenkovich@rsmas.miami.edu

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  • Bauer, S., M. S. Swenson, and A. Griffa, 2002: Eddy mean flow decomposition and eddy diffusivity estimates in the tropical Pacific Ocean: 2. Results. J. Geophys. Res., 107 , 3154. doi:10.1029/2000JC000613.

    • Search Google Scholar
    • Export Citation

  • Berloff, P., J. McWilliams, and A. Bracco, 2002: Material transport in oceanic gyres. Part I: Phenomenology. J. Phys. Oceanogr., 32 , 764–796.

    • Search Google Scholar
    • Export Citation

  • Berloff, P., I. Kamenkovich, and J. Pedlosky, 2009: A model of multiple zonal jets in the oceans: Dynamical and kinematical analysis. J. Phys. Oceanogr., 39 , 2711–2734.

    • Search Google Scholar
    • Export Citation

  • Booth, J., and I. Kamenkovich, 2008: Isolating the role of transient mesoscale eddies in mixing of a passive tracer in an eddy resolving model. J. Geophys. Res., 113 , C05021. doi:10.1029/2007JC004510.

    • Search Google Scholar
    • Export Citation

  • Boyer, T., S. Levitus, H. Garcia, R. Locarnini, C. Stephens, and J. Antonov, 2005: Objective analyses of annual, seasonal, and monthly temperature and salinity for the World Ocean on a 0.25 degree grid. Int. J. Climatol., 25 , 931–945.

    • Search Google Scholar
    • Export Citation

  • Cessi, P., and M. Fantini, 2004: The eddy-driven thermocline. J. Phys. Oceanogr., 34 , 2642–2658.

  • Davis, R. E., 1991: Observing the general circulation with floats. Deep-Sea Res., 38 , (Suppl. 1). 531–571.

  • Galperin, B., H. Nakano, H. Huang, and S. Sukoriansky, 2004: The ubiquitous zonal jets in the atmospheres of giant planets and Earth’s oceans. Geophys. Res. Lett., 31 , L13303. doi:10.1029/2004GL019691.

    • Search Google Scholar
    • Export Citation

  • Gille, S., and R. Davis, 1999: The influence of mesoscale eddies on coarsely resolved density: An examination of subgrid-scale parameterization. J. Phys. Oceanogr., 29 , 1109–1123.

    • Search Google Scholar
    • Export Citation

  • Henning, C. C., and G. Vallis, 2005: The effects of mesoscale eddies on the stratification and transport of an ocean with a circumpolar channel. J. Phys. Oceanogr., 35 , 880–896.

    • Search Google Scholar
    • Export Citation

  • Hogg, N., and B. Owens, 1999: Direct measurement of the deep circulation within the Brazil basin. Deep-Sea Res., 46 , 335–353.

  • Huang, H-P., A. Kaplan, E. Curchitser, and N. Maximenko, 2007: The degree of anisotropy for mid-ocean currents from satellite observations and an eddy-permitting model simulation. J. Geophys. Res., 112 , C09005. doi:10.1029/2007JC004105.

    • Search Google Scholar
    • Export Citation

  • Kamenkovich, I., P. Berloff, and J. Pedlosky, 2009: Role of eddy forcing in the dynamics of multiple zonal jets in the North Atlantic. J. Phys. Oceanogr., 39 , 1361–1379.

    • Search Google Scholar
    • Export Citation

  • LaCasce, J. H., 2000: Floats and f/h. J. Mar. Res., 58 , 61–85.

  • LaCasce, J. H., 2008: Statistics from Lagrangian observations. Prog. Oceanogr., 77 , 1–29.

  • LaCasce, J. H., and A. Bower, 2000: Relative dispersion in the subsurface North Atlantic. J. Mar. Res., 58 , 863–894.

  • Ledwell, J. R., A. J. Watson, and C. S. Law, 1993: Evidence for slow mixing across the pycnocline from an open-ocean tracer-release experiment. Nature, 364 , 701–703.

    • Search Google Scholar
    • Export Citation

  • Lee, M-M., A. J. G. Nurser, A. C. Coward, and B. A. de Cuevas, 2009: Effective eddy diffusivities inferred from a point release tracer in an eddy-resolving ocean model. J. Phys. Oceanogr., 39 , 894–914.

    • Search Google Scholar
    • Export Citation

  • Lumpkin, R., A-M. Treguier, and K. Speer, 2002: Lagrangian eddy scales in the northern Atlantic Ocean. J. Phys. Oceanogr., 32 , 2425–2440.

    • Search Google Scholar
    • Export Citation

  • Marshall, J., E. Shuckburgh, H. Jones, and C. Hill, 2006: Estimates and implications of surface eddy diffusivity in the Southern Ocean derived from tracer transport. J. Phys. Oceanogr., 36 , 1806–1821.

    • Search Google Scholar
    • Export Citation

  • Maximenko, N., B. Bang, and H. Sasaki, 2005: Observational evidence of alternating zonal jets in the world ocean. Geophys. Res. Lett., 32 , L12607. doi:10.1029/2005GL022728.

    • Search Google Scholar
    • Export Citation

  • Nakamura, M., and Y. Chao, 2000: On the eddy isopycnal thickness diffusivity of the Gent–McWilliams subgrid mixing parameterization. J. Climate, 13 , 502–510.

    • Search Google Scholar
    • Export Citation

  • Nakano, H., and H. Hasumi, 2005: A series of zonal jets embedded in the broad zonal flows in the Pacific obtained in eddy-permitting ocean general circulation models. J. Phys. Oceanogr., 35 , 474–488.

    • Search Google Scholar
    • Export Citation

  • Owens, W. B., 1984: A synoptic and statistical description of the Gulf Stream and subtropical gyre using SOFAR floats. J. Phys. Oceanogr., 14 , 104–113.

    • Search Google Scholar
    • Export Citation

  • Pacanowski, R. C., and S. M. Griffies, 1999: MOM 3.0 manual. NOAA/GFDL Tech. Rep., 680 pp.

  • Radko, T., and J. Marshall, 2004: Eddy-induced diapycnal fluxes and their role in the maintenance of the thermocline. J. Phys. Oceanogr., 34 , 372–383.

    • Search Google Scholar
    • Export Citation

  • Rhines, P., 1994: Jets. Chaos, 4 , 313–339.

  • Richards, K., N. Maximenko, F. Bryan, and H. Sasaki, 2006: Zonal jets in the Pacific Ocean. Geophys. Res. Lett., 33 , L03605. doi:10.1029/2005GL024645.

    • Search Google Scholar
    • Export Citation

  • Roberts, M., and D. Marshall, 2000: On the validity of downgradient eddy closures in ocean models. J. Geophys. Res., 105 , 28613–28627.

    • Search Google Scholar
    • Export Citation

  • Sallee, J-B., K. Speer, R. Morrow, and R. Lumpkin, 2008: An estimate of Lagrangian eddy statistics and diffusion in the mixed layer of the Southern Ocean. J. Mar. Res., 66 , 441–463.

    • Search Google Scholar
    • Export Citation

  • Scott, R. B., B. K. Arbic, C. L. Holland, B. Qiu, and A. Sen, 2008: Zonal versus meridional velocity variance in satellite observations and realistic and idealized ocean circulation models. Ocean Modell., 23 , 102–112.

    • Search Google Scholar
    • Export Citation

  • Smith, K. S., 2005: Tracer transport along and across coherent jets in two-dimensional turbulent flow. J. Fluid Mech., 544 , 133–142.

  • Talley, L. D., 2003: Shallow, intermediate, and deep overturning components of the global heat budget. J. Phys. Oceanogr., 33 , 530–560.

    • Search Google Scholar
    • Export Citation

  • Taylor, G. I., 1953: Dispersion of soluble matter in solvent flowing slowly through a tube. Proc. Roy. Soc. London, A219 , 186–203.

  • Thompson, A., and W. Young, 2007: Baroclinic eddy heat fluxes: zonal flows and energy balance. J. Atmos. Sci., 64 , 3214–3231.

  • Treguier, A., N. Hogg, M. Maltrud, K. Speer, and V. Thierry, 2003: The origin of deep zonal flows in the Brazil basin. J. Phys. Oceanogr., 33 , 580–599.

    • Search Google Scholar
    • Export Citation

  • Veneziani, M., A. Griffa, A. M. Reynolds, Z. D. Garraffo, and E. P. Chassignet, 2005: Parameterizations of Lagrangian spin statistics and particle dispersion in the presence of coherent vortices. J. Mar. Res., 63 , 1057–1083.

    • Search Google Scholar
    • Export Citation

  • Young, W. R., P. B. Rhines, and C. J. R. Garrett, 1982: Shear-flow dispersion, internal waves and horizontal mixing in the oceans. J. Phys. Oceanogr., 12 , 515–527.

    • Search Google Scholar
    • Export Citation
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