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Article Type:
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Spatial Variations of Stirring in the Surface Ocean: A Case Study of the Tasman Sea

Darryn W. Waugh Department of Earth and Planetary Science, The Johns Hopkins University, Baltimore, Maryland

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Edward R. Abraham National Institute of Water and Atmospheric Research, Wellington, New Zealand

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Melissa M. Bowen National Institute of Water and Atmospheric Research, Wellington, New Zealand

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Print Publication:
01 Mar 2006
DOI:
https://doi.org/10.1175/JPO2865.1
Page(s):
526–542
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Abstract

Stirring in the Tasman Sea is examined using surface geostrophic currents derived from satellite altimeter measurements. Calculations of the distribution of finite-time Lyapunov exponents (FTLEs) indicate that the stirring in this region is not uniform and stretching rates over 15 days vary from less than 0.02 day−1 to over 0.3 day−1. These variations occur at both small (∼10 km) and large (∼1000 km) scales and in both cases are linked to dynamical features of the flow. The small-scale variations are related to the characteristics of coherent vortex structures, and there are low FTLEs inside vortices and filaments of high FTLEs in strain-dominated regions surrounding these vortices. Regional variations in the stirring are closely related to variations in mesoscale activity and eddy kinetic energy (EKE). High values of mean FTLE occur in regions of high EKE (highest mean values of around 0.2 day−1 occur in the East Australia Current separation region) whereas small values occur in regions with low EKE (mean values around 0.03 day−1 in the east Tasman Sea). There is a compact relationship between the mean FTLEs and EKE, raising the possibility of using the easily calculated EKE to estimate the stirring. This possibility is even more intriguing because the FTLE distributions can be approximated, for the time scales considered here, by Weibull distributions with shape parameter equal to 1.6, which can be defined from the mean value alone.

Corresponding author address: Darryn W. Waugh, Dept. of Earth and Planetary Science, The Johns Hopkins University, 3400 N. Charles St., Baltimore, MD 21218. Email: waugh@jhu.edu

Abstract

Stirring in the Tasman Sea is examined using surface geostrophic currents derived from satellite altimeter measurements. Calculations of the distribution of finite-time Lyapunov exponents (FTLEs) indicate that the stirring in this region is not uniform and stretching rates over 15 days vary from less than 0.02 day−1 to over 0.3 day−1. These variations occur at both small (∼10 km) and large (∼1000 km) scales and in both cases are linked to dynamical features of the flow. The small-scale variations are related to the characteristics of coherent vortex structures, and there are low FTLEs inside vortices and filaments of high FTLEs in strain-dominated regions surrounding these vortices. Regional variations in the stirring are closely related to variations in mesoscale activity and eddy kinetic energy (EKE). High values of mean FTLE occur in regions of high EKE (highest mean values of around 0.2 day−1 occur in the East Australia Current separation region) whereas small values occur in regions with low EKE (mean values around 0.03 day−1 in the east Tasman Sea). There is a compact relationship between the mean FTLEs and EKE, raising the possibility of using the easily calculated EKE to estimate the stirring. This possibility is even more intriguing because the FTLE distributions can be approximated, for the time scales considered here, by Weibull distributions with shape parameter equal to 1.6, which can be defined from the mean value alone.

Corresponding author address: Darryn W. Waugh, Dept. of Earth and Planetary Science, The Johns Hopkins University, 3400 N. Charles St., Baltimore, MD 21218. Email: waugh@jhu.edu

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  • Abraham, E. R., and M. M. Bowen, 2002: Chaotic stirring by a mesoscale surface–ocean flow. Chaos, 12 , 373–381.

  • Abraham, E. R., C. S. Law, P. W. Boyd, S. J. Lavender, M. T. Maldonado, and A. R. S. Bowie, 2000: Importance of stirring in the development of an iron-fertilized phytoplankton bloom. Nature, 407 , 727–730.

    • Search Google Scholar
    • Export Citation

  • Artale, V., G. Boffeta, A. Celani, M. Cencini, and A. Vulpianii, 1997: Dispersion of passive tracers in closed basins: Beyond the diffusion coefficient. Phys. Fluids, 9 , 3162–3171.

    • Search Google Scholar
    • Export Citation

  • Babiano, A., C. Basdevant, and R. Sadourny, 1985: Structure functions and dispersion laws in two-dimensional turbulence. J. Atmos. Sci, 42 , 941–949.

    • Search Google Scholar
    • Export Citation

  • Bartello, P., 2000: Using low-resolution winds to deduce fine structure in tracers. Atmos.–Ocean, 38 , 303–320.

  • Bennett, A. F., 1984: Relative dispersion: Local and nonlocal dynamics. J. Atmos. Sci, 41 , 1881–1886.

  • Boffetta, A., G. Lacorata, G. Redaelii, and A. Vulpiani, 2001: Detecting barriers to transport: A review of different techniques. Physica D, 159 , 58–70.

    • Search Google Scholar
    • Export Citation

  • Bowman, K. P., 1993: Large-scale isentropic mixing properties of the Antarctic polar vortex from analyzed winds. J. Geophys. Res, 98 , 23013–23027.

    • Search Google Scholar
    • Export Citation

  • Bracco, A., J. von Hardenberg, A. Provenzale, J. B. Weiss, and J. C. McWilliams, 2004: Dispersion and mixing in quasigeostrophic turbulence. Phys. Rev. Lett, 92 ., doi:10.1103/PhysRevLett.92.084501.

    • Search Google Scholar
    • Export Citation

  • Brachet, M. E., M. Meneguzzi, H. Politano, and P. L. Sulem, 1988: The dynamics of freely decaying two-dimensional turbulence. J. Fluid Mech, 194 , 333–349.

    • Search Google Scholar
    • Export Citation

  • Bradbury, I. R., and P. V. R. Snelgrove, 2001: Contrasting larval transport in demersal fish and benthic invertebrates: The roles of behaviour and advective processes in determining spatial pattern. Can. J. Fish. Aquatic Sci, 58 , 811–823.

    • Search Google Scholar
    • Export Citation

  • Chiswell, S. M., J. Wilkin, J. D. Booth, and B. Stanton, 2003: Trans-Tasman Sea larval transport: Is Australia a source for New Zealand rock lobsters? Mar. Ecol. Progr. Ser, 247 , 173–182.

    • Search Google Scholar
    • Export Citation

  • Coauthors, 2004: Southern Ocean iron enrichment experiment: Carbon cycling in high- and low-Si waters. Science, 304 , 408–414.

  • Conradsen, K., L. B. Nielsen, and L. P. Prahm, 1984: Review of Weibull statistics for estimation of wind speed distributions. J. Climate Appl. Meteor, 23 , 1173–1183.

    • Search Google Scholar
    • Export Citation

  • d'Ovidio, F., V. Fernández, E. Hernández-García, and C. López, 2004: Mixing structures in the Mediterranean Sea from finite-size Lyapunov exponents. Geophys. Res. Lett, 31 .L17203, doi:10.1029/2004GL020328.

    • Search Google Scholar
    • Export Citation

  • Ducet, N., P. Y. Le Traon, and G. Reverdin, 2000: Global high-resolution mapping of ocean circulation from TOPEX/Poseidon and ERS-1 and -2. J. Geophys. Res, 105 , 19477–19498.

    • Search Google Scholar
    • Export Citation

  • Eckart, C., 1948: An analysis of stirring and mixing processes in incompressible fluids. J. Mar. Res, 7 , 265–275.

  • Elhmaïdi, D., A. Provenzal, and A. Babinao, 1993: Elementary topology of two-dimensional turbulence from a Lagrangain viewpoint and single-particle dispersion. J. Fluid Mech, 257 , 533–558.

    • Search Google Scholar
    • Export Citation

  • Fairlie, T. D. A., R. B. Pierce, J. A. Al-Saadi, W. L. Grose, J. M. Russell III, M. H. Proffitt, and C. R. Webster, 1999: The contribution of mixing in Lagrangian photochemical predictions of polar ozone loss over the Arctic in summer 1997. J. Geophys. Res, 104 , 26597–26609.

    • Search Google Scholar
    • Export Citation

  • Farnetani, C. G., and H. Samuel, 2003: Lagrangian structure and stirring in the earth's mantle. Earth Planet. Sci. Lett, 206 , 335–348.

    • Search Google Scholar
    • Export Citation

  • Garrett, C., 1983: On the initial streakiness of a dispersing tracer in two- and three-dimensional turbulence. Dyn. Atmos. Oceans, 7 , 265–277.

    • Search Google Scholar
    • Export Citation

  • Haller, G., 2000: Lagrangian coherent structures from approximate velocity data. Phys. Fluids, 14 , 1851–1861.

  • Haller, G., 2001: Lagrangian structures and the rate of strain in a partition of two-dimensional turbulence. Phys. Fluids, 13 , 3365–3385.

    • Search Google Scholar
    • Export Citation

  • Haynes, P. H., 1990: High-resolution three-dimensional modelling of stratospheric flows: Quasi-2D turbulence dominated by a single vortex. Topological Fluid Mechanics, H. K. Moffatt and A. Tsinober, Eds., Cambridge University Press, 345–354.

  • Hazell, D. R., and M. H. England, 2003: Prediction of the rate of radioactive material in the South Pacific Ocean using a global high-resolution model. J. Environ. Radio, 65 , 329–355.

    • Search Google Scholar
    • Export Citation

  • Hua, B. K., and P. Klein, 1998: An exact criterion for the stirring properties of nearly two-dimensional turbulence. Physica D, 113 , 98–110.

    • Search Google Scholar
    • Export Citation

  • Isern-Fontanet, J., E. Garcia-Ladona, and J. Font, 2003: Identification of marine eddies from altimetric maps. J. Atmos. Oceanic Technol, 20 , 772–778.

    • Search Google Scholar
    • Export Citation

  • Isern-Fontanet, J., J. Font, E. Garcia-Ladona, M. Emelianov, C. Millot, and I. Taupier-Letage, 2004: Spatial structure of anticyclonic eddies in the Algerian basin (Mediterranean Sea) analyzed using the Okubo–Weiss parameter. Deep Sea Res, 51B , 3009–3028.

    • Search Google Scholar
    • Export Citation

  • Joseph, B., and P. S. Swathi, 1999: Lagrangian particle transport in the Indian Ocean: A model study. J. Geophys. Res, 104 , 5211–5224.

    • Search Google Scholar
    • Export Citation

  • Koh, T-Y., and B. Legras, 2002: Hyperbolic lines and the stratospheric polar vortex. Chaos, 12 , 382–394.

  • LaCasce, J. H., and C. Ohlmann, 2003: Relative dispersion at the surface of the Gulf of Mexico. J. Mar. Res, 61 , 285–312.

  • Lacorata, G., E. Aurell, and A. Vulpiani, 2001: Drifter dispersion in the Adriatic Sea: Lagrangian data and chaotic model. Ann. Geophys, 19 , 121–129.

    • Search Google Scholar
    • Export Citation

  • Lapeyre, G., 2002: Characterization of finite-time Lyapunov exponents and vectors in two-dimensional turbulence. Chaos, 12 , 688–698.

  • Lapeyre, G., P. Klein, and B. L. Hua, 1999: Does the tracer gradient vector align with the strain eigenvectors in 2D turbulence? Phys. Fluids, 11 , 3729–3737.

    • Search Google Scholar
    • Export Citation

  • 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

  • Lumpkin, R., A. M. Treguier, and K. Speer, 2002: Lagrangian eddy scales in the North Atlantic Ocean. J. Phys. Oceanogr, 32 , 2425–2490.

    • Search Google Scholar
    • Export Citation

  • Mahadevan, A., and J. W. Campbell, 2002: Biogeochemical patchiness at the sea surface. Geophys. Res. Lett, 29 .1926, doi:10.1029/2001GL014116.

    • Search Google Scholar
    • Export Citation

  • Martin, A. P., 2003: Phytoplankton patchiness: The role of lateral stirring and mixing. Progress in Oceanography, Vol. 57, Pergamon, 125–174.

  • McWilliams, J. C., 1984: The emergence of isolated coherent vortices in turbulent flow. J. Fluid Mech, 146 , 21–43.

  • Müller, P., and C. Garrett, 2002: From stirring to mixing in a stratified ocean. Oceanography, 15 , 12–19.

  • Neufeld, Z., C. Lopez, E. Hernandez-Garcia, and T. Tel, 2000: Multifractal structure of chaotically advected chemical fields. Phys. Rev. E, 61 , 3857–3866.

    • Search Google Scholar
    • Export Citation

  • Ngan, K., and T. G. Shepherd, 1999: A closer look at chaotic advection in the stratosphere. Part II: Statistical diagnostics. J. Atmos. Sci, 56 , 4153–4166.

    • Search Google Scholar
    • Export Citation

  • Nilsson, C. S., and G. R. Creswell, 1981: The formation and evolution of East Australian Current warm-core eddies. Progress in Oceanography, Vol. 9, Pergamon, 133–183.

  • Norton, W. A., 1994: Breaking Rossby waves in a model stratosphere diagnosed by a vortex-following coordinate system and a contour advection technique. J. Atmos. Sci, 51 , 654–673.

    • Search Google Scholar
    • Export Citation

  • Okubo, A., 1970: Horizontal dispersion of floatable particles in the vicinity of velocity singularity such as convergences. Deep-Sea Res, 17 , 445–454.

    • Search Google Scholar
    • Export Citation

  • Pasquero, C., A. Provenzale, and A. Babiano, 2001: Parameterization of dispersion in two-dimensional turbulence. J. Fluid Mech, 439 , 279–303.

    • Search Google Scholar
    • Export Citation

  • Pierce, B. R., and T. D. A. Fairlie, 1993: Chaotic advection in the stratosphere: Implications for the dispersal of chemically perturbed air from the polar vortex. J. Geophys. Res, 98 , 18589–18595.

    • Search Google Scholar
    • Export Citation

  • Pierrehumbert, R. T., and H. Yang, 1993: Global chaotic mixing on isentropic surfaces. J. Atmos. Sci, 50 , 2462–2480.

  • Provenzale, A., A. R. Osborne, A. D. Kirwan, and L. Bergamasco, 1991: The study of fluid parcel trajectories in large-scale ocean flows. Nonlinear Topics in Ocean Physics, A. R. Osborne, Ed., Elsevier, 367–401.

    • Search Google Scholar
    • Export Citation

  • Ridgway, K. R., and J. R. Dunn, 2003: Mesoscale structure of the mean East Australian Current system and its relationship with topography. Progress in Oceanography, Vol. 56, Pergamon, 189–222.

  • Ridgway, K. R., J. R. Dunn, and J. L. Wilkin, 2002: Ocean interpolation by four-dimensional weighted least squares—Application to the waters around Australasia. J. Atmos. Oceanic Technol, 19 , 1357–1375.

    • Search Google Scholar
    • Export Citation

  • Rio, M-H., and F. Hernandez, 2004: A mean dynamic topography computed over the World Ocean from altimetry, in situ measurements and a geoid model. J. Geophys. Res, 109 .C12032, doi:10.1029/2003JC002226.

    • Search Google Scholar
    • Export Citation

  • Roemmich, D., and P. Sutton, 1998: The mean and variability of ocean circulation past northern New Zealand: Determining the representativeness of hydrographic climatologies. J. Geophys. Res, 103 , 13041–13054.

    • Search Google Scholar
    • Export Citation

  • Sanderson, B. G., and D. A. Booth, 1991: The fractal dimension of drifter trajectories and estimates for horizontal eddy diffusivity. Tellus, 43A , 334–349.

    • Search Google Scholar
    • Export Citation

  • Shepherd, T. G., J. N. Koshyk, and K. Ngan, 2000: On the nature of large-scale mixing in the stratosphere and mesosphere. J. Geophys. Res, 105 , 12433–12446.

    • Search Google Scholar
    • Export Citation

  • Stammer, D., 1997: Global characteristics of ocean variability estimated from TOPEX/Poseidon altimeter measurements. J. Phys. Oceanogr, 27 , 1743–1769.

    • Search Google Scholar
    • Export Citation

  • Stammer, D., 1998: On eddy characteristics, eddy transport, and mean flow properties. J. Phys. Oceanogr, 28 , 727–739.

  • Tilburg, C. E., H. E. Hurlburt, J. J. O'Brien, and J. F. Shriver, 2001: The dynamics of the East Australian Current system: The Tasman front, the East Auckland Current, and the East Cape Current. J. Phys. Oceanogr, 31 , 2917–2943.

    • Search Google Scholar
    • Export Citation

  • Tilburg, C. E., B. Subrahmanyam, and J. J. O'Brien, 2002: Ocean color variability in the Tasman Sea. Geophys. Res. Lett, 29 , 1487–1490.

    • Search Google Scholar
    • Export Citation

  • von Hardenberg, J., K. Fraedrich, F. Lunkeit, and A. Provenzale, 2000: Transient chaotic mixing during a baroclinic life cycle. Chaos, 10 , 122–134.

    • Search Google Scholar
    • Export Citation

  • Waugh, D. W., and R. A. Plumb, 1994: Contour advection with surgery: A technique for investigating finescale structure in tracer transport. J. Atmos. Sci, 51 , 530–540.

    • Search Google Scholar
    • Export Citation

  • Waugh, D. W., and P. P. Rong, 2002: Interannual variability in the decay of lower stratospheric Arctic vortices. J. Meteor. Soc. Japan, 80 , 997–1012.

    • Search Google Scholar
    • Export Citation

  • Coauthors, 1994: Transport out of the lower stratospheric Arctic vortex by Rossby wave breaking. J. Geophys. Res, 99 , 1071–1088.

  • Weiss, J., 1991: The dynamics of enstrophy transfer in two-dimensional hydrodynamics. Physica D, 48 , 273–294.

  • Wilkin, J. L., M. M. Bowen, and W. J. Emery, 2002: Mapping mesoscale currents by optimal interpolation of satellite radiometer and altimeter data. Ocean Dyn, 52 , 95–103.

    • Search Google Scholar
    • Export Citation

  • Yang, H., 1996: The subtropical/subpolar gyre exchange in the presence of annually migrating wind and a meandering jet: Water mass exchange. J. Phys. Oceanogr, 26 , 115–130.

    • Search Google Scholar
    • Export Citation

  • Zhurbas, V., and I. S. Oh, 2004: Drifter-derived maps of lateral diffusivity in the Pacific and Atlantic Oceans in relation to surface circulation patterns. J. Geophys. Res, 109 .C05015, doi/10.1029/2003JC002241.

    • Search Google Scholar
    • Export Citation
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