Editorial Type:
Article
Article Type:
Research Article

Generation of Internal Waves by Eddies Impinging on the Western Boundary of the North Atlantic

L. Clément National Oceanography Centre, University of Southampton, Southampton, United Kingdom

Search for other papers by L. Clément in
Current site
Google Scholar
PubMed Close
,
E. Frajka-Williams National Oceanography Centre, University of Southampton, Southampton, United Kingdom

Search for other papers by E. Frajka-Williams in
Current site
Google Scholar
PubMed Close
,
K. L. Sheen National Oceanography Centre, University of Southampton, Southampton, United Kingdom, and Met Office Hadley Centre, Exeter, United Kingdom

Search for other papers by K. L. Sheen in
Current site
Google Scholar
PubMed Close
,
J. A. Brearley British Antarctic Survey, Cambridge, United Kingdom

Search for other papers by J. A. Brearley in
Current site
Google Scholar
PubMed Close
, and
A. C. Naveira Garabato National Oceanography Centre, University of Southampton, Southampton, United Kingdom

Search for other papers by A. C. Naveira Garabato in
Current site
Google Scholar
PubMed Close
Print Publication:
01 Apr 2016
DOI:
https://doi.org/10.1175/JPO-D-14-0241.1
Page(s):
1067–1079
Restricted access

Abstract

Despite the major role played by mesoscale eddies in redistributing the energy of the large-scale circulation, our understanding of their dissipation is still incomplete. This study investigates the generation of internal waves by decaying eddies in the North Atlantic western boundary. The eddy presence and decay are measured from the altimetric surface relative vorticity associated with an array of full-depth current meters extending ~100 km offshore at 26.5°N. In addition, internal waves are analyzed over a topographic rise from 2-yr high-frequency measurements of an acoustic Doppler current profiler (ADCP), which is located 13 km offshore in 600-m deep water. Despite an apparent polarity independence of the eddy decay observed from altimetric data, the flow in the deepest 100 m is enhanced for anticyclones (25.2 cm s−1) compared with cyclones (−4.7 cm s−1). Accordingly, the internal wave field is sensitive to this polarity-dependent deep velocity. This is apparent from the eddy-modulated enhanced dissipation rate, which is obtained from a finescale parameterization and exceeds 10−9 W kg−1 for near-bottom flows greater than 8 cm s−1. The present study underlines the importance of oceanic western boundaries for removing the energy of low-mode westward-propagating eddies to higher-mode internal waves.

Current affiliation: Lamont-Doherty Earth Observatory, Columbia University, Palisades, New York.

Corresponding author address: Louis Clément, Lamont-Doherty Earth Observatory, Columbia University, 61 Route 9W, P.O. Box 1000, Palisades, NY 10964. E-mail: lclement@ldeo.columbia.edu

Abstract

Despite the major role played by mesoscale eddies in redistributing the energy of the large-scale circulation, our understanding of their dissipation is still incomplete. This study investigates the generation of internal waves by decaying eddies in the North Atlantic western boundary. The eddy presence and decay are measured from the altimetric surface relative vorticity associated with an array of full-depth current meters extending ~100 km offshore at 26.5°N. In addition, internal waves are analyzed over a topographic rise from 2-yr high-frequency measurements of an acoustic Doppler current profiler (ADCP), which is located 13 km offshore in 600-m deep water. Despite an apparent polarity independence of the eddy decay observed from altimetric data, the flow in the deepest 100 m is enhanced for anticyclones (25.2 cm s−1) compared with cyclones (−4.7 cm s−1). Accordingly, the internal wave field is sensitive to this polarity-dependent deep velocity. This is apparent from the eddy-modulated enhanced dissipation rate, which is obtained from a finescale parameterization and exceeds 10−9 W kg−1 for near-bottom flows greater than 8 cm s−1. The present study underlines the importance of oceanic western boundaries for removing the energy of low-mode westward-propagating eddies to higher-mode internal waves.

Current affiliation: Lamont-Doherty Earth Observatory, Columbia University, Palisades, New York.

Corresponding author address: Louis Clément, Lamont-Doherty Earth Observatory, Columbia University, 61 Route 9W, P.O. Box 1000, Palisades, NY 10964. E-mail: lclement@ldeo.columbia.edu
Save
Cover Journal of Physical Oceanography
Journal of Physical Oceanography

  • Baines, P. G., 1995: Topographic Effects in Stratified Flows. Cambridge University Press, 500 pp.

  • Bell, T. H., 1975: Lee waves in stratified flows with simple harmonic time dependence. J. Fluid Mech., 67, 705–722, doi:10.1017/S0022112075000560.

    • Search Google Scholar
    • Export Citation

  • Brearley, J. A., K. L. Sheen, A. C. Naveira Garabato, D. A. Smeed, and S. Waterman, 2013: Eddy-induced modulation of turbulent dissipation over rough topography in the Southern Ocean. J. Phys. Oceanogr., 43, 2288–2308, doi:10.1175/JPO-D-12-0222.1.

    • Search Google Scholar
    • Export Citation

  • Bryden, H. L., W. E. Johns, and P. M. Saunders, 2005: Deep western boundary current east of Abaco: Mean structure and transport. J. Mar. Res., 63, 35–57, doi:10.1357/0022240053693806.

    • Search Google Scholar
    • Export Citation

  • Bühler, O., and M. E. McIntyre, 2005: Wave capture and wave-vortex duality. J. Fluid Mech., 534, 67–95, doi:10.1017/S0022112005004374.

    • Search Google Scholar
    • Export Citation

  • Clément, L., E. Frajka-Williams, Z. B. Szuts, and S. A. Cunningham, 2014: Vertical structure of eddies and Rossby waves, and their effect on the Atlantic meridional overturning circulation at 26.5°N. J. Geophys. Res., 119, 6479–6498, doi:10.1002/2014JC010146.

    • Search Google Scholar
    • Export Citation

  • Cunningham, S. A., and Coauthors, 2007: Temporal variability of the Atlantic meridional overturning circulation at 26.5°N. Science, 317, 935–938, doi:10.1126/science.1141304.

    • Search Google Scholar
    • Export Citation

  • D’Asaro, E. A., 1985: The energy flux from the wind to near-inertial motions in the surface mixed layer. J. Phys. Oceanogr., 15, 1043–1059, doi:10.1175/1520-0485(1985)015<1043:TEFFTW>2.0.CO;2.

    • Search Google Scholar
    • Export Citation

  • Dee, D. P., and Coauthors, 2011: The ERA-Interim reanalysis: Configuration and performance of the data assimilation system. Quart. J. Roy. Meteor. Soc., 137, 553–597, doi:10.1002/qj.828.

    • Search Google Scholar
    • Export Citation

  • Ferrari, R., and C. Wunsch, 2009: Ocean circulation kinetic energy: Reservoirs, sources, and sinks. Annu. Rev. Fluid Mech., 41, 253–282, doi:10.1146/annurev.fluid.40.111406.102139.

    • Search Google Scholar
    • Export Citation

  • Frajka-Williams, E., W. E. Johns, C. S. Meinen, L. M. Beal, and S. A. Cunningham, 2013: Eddy impacts on the Florida Current. Geophys. Res. Lett., 40, 349–353, doi:10.1002/grl.50115.

    • Search Google Scholar
    • Export Citation

  • Gill, A. E., 1982: Atmosphere-Ocean Dynamics. International Geophysics Series, Vol. 30, Academic Press, 662 pp.

  • Gill, A. E., J. S. A. Green, and A. J. Simmons, 1974: Energy partition in the large-scale ocean circulation and the production of mid-ocean eddies. Deep-Sea Res. Oceanogr. Abstr., 21, 499–528, doi:10.1016/0011-7471(74)90010-2.

    • Search Google Scholar
    • Export Citation

  • Gonella, J., 1972: A rotary-component method for analysing meteorological and oceanographic vector time series. Deep-Sea Res. Oceanogr. Abstr., 19, 833–846, doi:10.1016/0011-7471(72)90002-2.

    • Search Google Scholar
    • Export Citation

  • Gregg, M. C., 1989: Scaling turbulent dissipation in the thermocline. J. Geophys. Res., 94, 9686–9698, doi:10.1029/JC094iC07p09686.

  • Gregg, M. C., and E. Kunze, 1991: Shear and strain in Santa Monica Basin. J. Geophys. Res., 96, 16 709–16 719, doi:10.1029/91JC01385.

  • Gregg, M. C., T. B. Sanford, and D. P. Winkel, 2003: Reduced mixing from the breaking of internal waves in equatorial ocean waters. Nature, 422, 513–515, doi:10.1038/nature01507.

    • Search Google Scholar
    • Export Citation

  • Henyey, F. S., J. Wright, and S. M. Flatté, 1986: Energy and action flow through the internal wave field: An eikonal approach. J. Geophys. Res., 91, 8487–8495, doi:10.1029/JC091iC07p08487.

    • Search Google Scholar
    • Export Citation

  • Hogg, A. M., W. K. Dewar, P. Berloff, and M. L. Ward, 2011: Kelvin wave hydraulic control induced by interactions between vortices and topography. J. Fluid Mech., 687, 194–208, doi:10.1017/jfm.2011.344.

    • Search Google Scholar
    • Export Citation

  • Johns, W. E., L. M. Beal, M. O. Baringer, J. R. Molina, S. A. Cunningham, T. Kanzow, and D. Rayner, 2008: Variability of shallow and deep western boundary currents off the Bahamas during 2004–05: Results from the 26°N RAPID-MOC array. J. Phys. Oceanogr., 38, 605–623, doi:10.1175/2007JPO3791.1.

    • Search Google Scholar
    • Export Citation

  • Klymak, J. M., S. Legg, and R. Pinkel, 2010: High-mode stationary waves in stratified flow over large obstacles. J. Fluid Mech., 644, 321–336, doi:10.1017/S0022112009992503.

    • Search Google Scholar
    • Export Citation

  • Köhler, J., C. Mertens, M. Walter, U. Stöber, M. Rhein, and T. Kanzow, 2014: Variability in the internal wave field induced by the Atlantic Deep Western Boundary Current at 16°N. J. Phys. Oceanogr., 44, 492–516, doi:10.1175/JPO-D-13-010.1.

    • Search Google Scholar
    • Export Citation

  • Kunze, E., 1985: Near inertial-wave propagation in geostrophic shear. J. Phys. Oceanogr., 15, 544–565, doi:10.1175/1520-0485(1985)015<0544:NIWPIG>2.0.CO;2.

    • Search Google Scholar
    • Export Citation

  • Kunze, E., E. Firing, J. M. Hummon, T. K. Chereskin, and A. M. Thurnherr, 2006: Global abyssal mixing inferred from lowered ADCP shear and CTD strain profiles. J. Phys. Oceanogr., 36, 1553–1576, doi:10.1175/JPO2926.1.

    • Search Google Scholar
    • Export Citation

  • Lee, T. N., W. E. Johns, R. J. Zantopp, and E. Fillenbaum, 1996: Moored observations of western boundary current variability and thermohaline circulation at 26.5°N in the subtropical North Atlantic. J. Phys. Oceanogr., 26, 962–983, doi:10.1175/1520-0485(1996)026<0962:MOOWBC>2.0.CO;2.

    • Search Google Scholar
    • Export Citation

  • Lelong, M.-P., and E. Kunze, 2013: Can barotropic tide–eddy interactions excite internal waves? J. Fluid Mech., 721, 1–27, doi:10.1017/jfm.2013.1.

    • Search Google Scholar
    • Export Citation

  • Liang, X., and A. M. Thurnherr, 2012: Eddy-modulated internal waves and mixing on a midocean ridge. J. Phys. Oceanogr., 42, 1242–1248, doi:10.1175/JPO-D-11-0126.1.

    • Search Google Scholar
    • Export Citation

  • MacCready, P., and G. Pawlak, 2001: Stratified flow along a corrugated slope: Separation drag and wave drag. J. Phys. Oceanogr., 31, 2824–2839, doi:10.1175/1520-0485(2001)031<2824:SFAACS>2.0.CO;2.

    • Search Google Scholar
    • Export Citation

  • Naveira Garabato, A. C., K. L. Polzin, B. A. King, K. J. Heywood, and M. Visbeck, 2004: Widespread intense turbulent mixing in the Southern Ocean. Science, 303, 210–213, doi:10.1126/science.1090929.

    • Search Google Scholar
    • Export Citation

  • Nikurashin, M., and R. Ferrari, 2010: Radiation and dissipation of internal waves generated by geostrophic motions impinging on small-scale topography: Application to the Southern Ocean. J. Phys. Oceanogr., 40, 2025–2042, doi:10.1175/2010JPO4315.1.

    • Search Google Scholar
    • Export Citation

  • Nycander, J., 2005: Generation of internal waves in the deep ocean by tides. J. Geophys. Res., 110, C10028, doi:10.1029/2004JC002487.

  • Osborn, T. R., 1980: Estimates of the local rate of vertical diffusion from dissipation estimates. J. Phys. Oceanogr., 10, 83–89, doi:10.1175/1520-0485(1980)010<0083:EOTLRO>2.0.CO;2.

    • Search Google Scholar
    • Export Citation

  • Pollard, R. T., and R. C. Millard, 1970: Comparison between observed and simulated wind-generated inertial oscillations. Deep-Sea Res. Oceanogr. Abstr., 17, 813–821, doi:10.1016/0011-7471(70)90043-4.

    • Search Google Scholar
    • Export Citation

  • Polzin, K. L., 2008: Mesoscale eddy–internal wave coupling. Part I: Symmetry, wave capture and results from the Mid-Ocean Dynamics Experiment. J. Phys. Oceanogr., 38, 2556–2574, doi:10.1175/2008JPO3666.1.

    • Search Google Scholar
    • Export Citation

  • Polzin, K. L., 2010: Mesoscale eddy–internal wave coupling. Part II: Energetics and results from PolyMode. J. Phys. Oceanogr., 40, 789–801, doi:10.1175/2009JPO4039.1.

    • Search Google Scholar
    • Export Citation

  • Polzin, K. L., J. M. Toole, and R. W. Schmitt, 1995: Finescale parameterizations of turbulent dissipation. J. Phys. Oceanogr., 25, 306–328, doi:10.1175/1520-0485(1995)025<0306:FPOTD>2.0.CO;2.

    • Search Google Scholar
    • Export Citation

  • Polzin, K. L., A. C. Naveira Garabato, T. N. Huussen, B. M. Sloyan, and S. Waterman, 2014: Finescale parameterizations of turbulent dissipation. J. Geophys. Res., 119, 1383–1419, doi:10.1002/2013JC008979.

    • Search Google Scholar
    • Export Citation

  • Salmon, R., 1978: Two-layer quasi-geostrophic turbulence in a simple special case. Geophys. Astrophys. Fluid Dyn., 10, 25–52, doi:10.1080/03091927808242628.

    • Search Google Scholar
    • Export Citation

  • Scott, R. B., and F. Wang, 2005: Direct evidence of an oceanic inverse kinetic energy cascade from satellite altimetry. J. Phys. Oceanogr., 35, 1650–1666, doi:10.1175/JPO2771.1.

    • Search Google Scholar
    • Export Citation

  • Sen, A., R. B. Scott, and B. K. Arbic, 2008: Global energy dissipation rate of deep-ocean low-frequency flows by quadratic bottom boundary layer drag: Computations from current-meter data. Geophys. Res. Lett., 35, L09606, doi:10.1029/2008GL033407.

    • Search Google Scholar
    • Export Citation

  • Sheen, K. L., and Coauthors, 2013: Rates and mechanisms of turbulent dissipation and mixing in the Southern Ocean: Results from the DIMES experiment. J. Geophys. Res. Oceans, 118, 2774–2792, doi:10.1002/jgrc.20217.

    • Search Google Scholar
    • Export Citation

  • St. Laurent, L., A. C. Naveira Garabato, J. R. Ledwell, A. M. Thurnherr, J. M. Toole, and A. J. Watson, 2012: Turbulent and diapycnal mixing in Drake Passage. J. Phys. Oceanogr., 42, 2143–2152, doi:10.1175/JPO-D-12-027.1.

    • Search Google Scholar
    • Export Citation

  • Vallis, G. K., 2006: Atmospheric and Oceanic Fluid Dynamics. Cambridge University Press, 745 pp.

  • Waterman, S., A. C. Naveira Garabato, and K. L. Polzin, 2013: Internal waves and turbulence in the Antarctic Circumpolar Current. J. Phys. Oceanogr., 43, 259–282, doi:10.1175/JPO-D-11-0194.1.

    • Search Google Scholar
    • Export Citation

  • Winters, K. B., and L. Armi, 2013: The response of a continuously stratified fluid to an oscillating flow past an obstacle. J. Fluid Mech., 727, 83–118, doi:10.1017/jfm.2013.247.

    • Search Google Scholar
    • Export Citation

  • Wunsch, C., 1998: The work done by the wind on the oceanic general circulation. J. Phys. Oceanogr., 28, 2332–2340, doi:10.1175/1520-0485(1998)028<2332:TWDBTW>2.0.CO;2.

    • Search Google Scholar
    • Export Citation

  • Zhai, X., H. L. Johnson, and D. P. Marshall, 2010: Significant sink of ocean-eddy energy near western boundaries. Nat. Geosci., 3, 608–612, doi:10.1038/ngeo943.

    • Search Google Scholar
    • Export Citation
All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 624 286 32
PDF Downloads 393 106 19