• A Corrigendum to this article was published on 18 November 2015

Abstract

Internal gravity waves, the subsurface analogue of the familiar surface gravity waves that break on beaches, are ubiquitous in the ocean. Because of their strong vertical and horizontal currents, and the turbulent mixing caused by their breaking, they affect a panoply of ocean processes, such as the supply of nutrients for photosynthesis1, sediment and pollutant transport2 and acoustic transmission3; they also pose hazards for man-made structures in the ocean4. Generated primarily by the wind and the tides, internal waves can travel thousands of kilometres from their sources before breaking5, making it challenging to observe them and to include them in numerical climate models, which are sensitive to their effects6,7. For over a decade, studies8,9,10,11 have targeted the South China Sea, where the oceans’ most powerful known internal waves are generated in the Luzon Strait and steepen dramatically as they propagate west. Confusion has persisted regarding their mechanism of generation, variability and energy budget, however, owing to the lack of in situ data from the Luzon Strait, where extreme flow conditions make measurements difficult. Here we use new observations and numerical models to (1) show that the waves begin as sinusoidal disturbances rather than arising from sharp hydraulic phenomena, (2) reveal the existence of >200-metre-high breaking internal waves in the region of generation that give rise to turbulence levels >10,000 times that in the open ocean, (3) determine that the Kuroshio western boundary current noticeably refracts the internal wave field emanating from the Luzon Strait, and (4) demonstrate a factor-of-two agreement between modelled and observed energy fluxes, which allows us to produce an observationally supported energy budget of the region. Together, these findings give a cradle-to-grave picture of internal waves on a basin scale, which will support further improvements of their representation in numerical climate predictions.

Access optionsAccess options

Rent or Buy article

Get time limited or full article access on ReadCube.

from$8.99

All prices are NET prices.

References

  1. 1.

    , & Physical and ecological processes of internal waves on an isolated reef ecosystem in the South China Sea. Geophys. Res. Lett. 34, 1–5 (2007)

  2. 2.

    , & Sediment resuspension and mixing by resonantly generated internal solitary waves. J. Phys. Oceanogr. 27, 1181–1196 (1997)

  3. 3.

    , , , & Internal wave effects on high-frequency acoustic propagation to horizontal arrays—experiment and implications to imaging. IEEE J. Oceanic Eng. 26, 102–112 (2001)

  4. 4.

    , & The influence of internal waves on deep-water drilling. J. Petrol. Technol. 30, 1497–1504 (1978)

  5. 5.

    & Surface manifestation of internal tides generated near Hawaii. Geophys. Res. Lett. 23, 2101–2104 (1996)

  6. 6.

    , , & Tidally driven mixing in a num-erical model of the ocean general circulation. Ocean Model. 6, 245–263 (2004)

  7. 7.

    , , & Sensitivity of the ocean state to the vertical distribution of internal-tide-driven mixing. J. Phys. Oceanogr. 43, 602–615 (2013)

  8. 8.

    et al. Internal solitons in the northeastern South China Sea, part I: sources and deep-water propagation. IEEE J. Oceanic Eng. 29, 1157–1181 (2004)

  9. 9.

    , & Numerical study of baroclinic tides in Luzon Strait. J. Oceanogr. 64, 789–802 (2008)

  10. 10.

    , & An overview of internal solitary waves in the South China Sea. Surv. Geophys. 33, 927–943 (2012)

  11. 11.

    & A review of internal solitary wave dynamics in the northern South China Sea. Prog. Oceanogr. 121, 7–23 (2014)

  12. 12.

    & Ocean circulation kinetic energy: reservoirs, sources, and sinks. Annu. Rev. Fluid Mech. 41, 253–282 (2009)

  13. 13.

    & Pilot whales follow internal solitary waves in the South China Sea. Mar. Mamm. Sci. 23, 193–196 (2007)

  14. 14.

    et al. From tides to mixing along the Hawaiian Ridge. Science 301, 355–357 (2003)

  15. 15.

    et al. Energy flux and dissipation in Luzon Strait: two tales of two ridges. J. Phys. Oceanogr. 41, 2211–2222 (2011)

  16. 16.

    Energy available for ocean mixing redistributed through long-range propagation of internal waves. Nature 423, 159–162 (2003)

  17. 17.

    et al. Three-dimensional double-ridge internal tide resonance in Luzon Strait. J. Phys. Oceanogr. 44, 850–869 (2014)

  18. 18.

    , & Breaking topographic lee waves in a tidal channel in Luzon Strait. Oceanography 25, 160–165 (2012)

  19. 19.

    , & South China Sea throughflow: a heat and freshwater conveyor. Geophys. Res. Lett. 33, L23617 (2006)

  20. 20.

    et al. Large-scale realistic modeling of M2 internal tide generation at the Luzon Strait. Geophys. Res. Lett. 40, 5704–5709 (2013)

  21. 21.

    & Nonlinear disintegration of the internal tide. J. Phys. Oceanogr. 38, 686–701 (2008)

  22. 22.

    , & Internal wave observations in the South China Sea: the role of rotation and nonlinearity. Atmosphere-Ocean 47, 267–280 (2009)

  23. 23.

    & The generation and evolution of nonlinear internal waves in the deep basin of the South China Sea. J. Phys. Oceanogr. 41, 1345–1363 (2011).

  24. 24.

    & Effects of Kuroshio intrusions on nonlinear internal waves in the South China Sea during winter. J. Geophys. Res. 118, 7081–7094 (2013)

  25. 25.

    , & Characterizing the nonlinear internal wave climate in the Northeastern South China Sea. Nonlinear Process. Geophys. 17, 481–498 (2010)

  26. 26.

    et al. Speed and evolution of nonlinear internal waves transiting the South China Sea. J. Phys. Oceanogr. 40, 1338–1355 (2010)

  27. 27.

    , , & Large-amplitude internal solitary waves observed in the northern South China Sea: properties and energetics. J. Phys. Oceanogr. 44, 1095–1115 (2014)

  28. 28.

    et al. An estimate of tidal energy lost to turbulence at the Hawaiian Ridge. J. Phys. Oceanogr. 36, 1148–1164 (2006)

  29. 29.

    , , , & The breaking and scattering of the internal tide on a continental slope. J. Phys. Oceanogr. 41, 926–945 (2011)

  30. 30.

    & Physical vs. numerical dispersion in nonhydrostatic ocean modeling. Ocean Model. 40, 72–86 (2011)

  31. 31.

    & Efficient inverse modeling of barotropic ocean tides. J. Atmos. Ocean. Technol. 19, 183–204 (2002)

  32. 32.

    & Global sea floor topography from satellite altimetry and ship depth soundings. Science 277, 1956–1962 (1997)

  33. 33.

    , & A comparison between the generalized Digital Environmental Model and Levitus climatologies. J. Geophys. Res. 95, 7167–7183 (1990)

  34. 34.

    & Buoyancy-driven circulation in an ocean basin with isopycnals intersecting the sloping boundary. J. Phys. Oceanogr. 26, 913–940 (1996)

  35. 35.

    et al. Modeling and prediction of internal waves in the South China Sea. Oceanography 24, 88–99 (2011)

  36. 36.

    , , , & A finite-volume, incompressible Navier Stokes model for studies of the ocean on parallel computers. J. Geophys. Res. 102 (C3). 5753–5766 (1997)

  37. 37.

    , , & A real-time coastal ocean prediction experiment for MREA04. J. Mar. Syst. 69, 17–28 (2008)

  38. 38.

    , & The generation and propagation of internal solitary waves in the South China Sea. J. Geophys. Res. Oceans 118, 6578–6589 (2013)

  39. 39.

    , & The variability of internal tides in the Northern South China Sea. J. Oceanogr. 69, 619–630 (2013)

  40. 40.

    , , & A real-time coastal ocean prediction experiment for MREA04. J. Mar. Syst. 69, 17–28 (2008)

  41. 41.

    et al. The HYCOM (HYbrid Coordinate Ocean Model) data assimilative system. J. Mar. Syst. 65, 60–83 (2007)

  42. 42.

    , , & The autonomous underwater glider “Spray”. IEEE J. Oceanic Eng. 26, 437–446 (2001)

  43. 43.

    , , & A moored profiling instrument. J. Atmos. Ocean. Technol. 16, 1816–1829 (1999)

  44. 44.

    , , & Acoustical measurement of nonlinear internal waves using the inverted echo sounder. J. Atmos. Ocean. Technol. 26, 2228–2242 (2009)

  45. 45.

    in Physical Processes in Lakes and Oceans (ed. Imberger, J.) Vol. 54 305–338 (American Geophysical Union, 1998)

  46. 46.

    Vertical overturns: a comparison of Thorpe and Ozmidov length scales. J. Geophys. Res. 87, 9601–9613 (1982)

  47. 47.

    , , , & Mixing in the Romanche fracture zone. J. Phys. Oceanogr. 28, 1929–1945 (1998)

  48. 48.

    , & Structure, propagation and mixing of energetic baroclinic tides in Mamala Bay, Oahu, Hawaii. J. Phys. Oceanogr. 36, 997–1018 (2006)

  49. 49.

    , & Relevance of the Thorpe length scale in stably stratified turbulence. Phys. Fluids 25, 076604 (2013)

  50. 50.

    , & Internal tide radiation from Mendocino Escarpment. J. Phys. Oceanogr. 33, 1510–1527 (2003)

  51. 51.

    , , , & Spatial and temporal variability of internal tides in Luzon Strait. J. Phys. Oceanogr. (in the press).

  52. 52.

    , & Estimating internal-wave energy fluxes in the ocean. J. Atmos. Ocean. Technol. 22, 1551–1570 (2005)

  53. 53.

    , , , & Internal tidal energy fluxes in the South China Sea from density and velocity measurements by gliders. J. Geophys. Res. 118, 1–11 (2013)

  54. 54.

    , , , & Energy transport by nonlinear internal waves. J. Phys. Oceanogr. 37, 1968–1988 (2007)

  55. 55.

    & Internal-tide generation and destruction by shoaling internal tides. Geophys. Res. Lett. 37, L23611 (2010)

  56. 56.

    & A simple mixing scheme for models that resolve breaking internal waves. Ocean Model. 33, 224–234 (2010)

  57. 57.

    , & Breaking internal lee waves at Kaena Ridge, Hawaii. Geophys. Res. Lett. 41, 906–912 (2014)

  58. 58.

    , , , & Energy flux of nonlinear internal waves in northern South China Sea. Geophys. Res. Lett. 33, 1–5 (2006)

  59. 59.

    , , & Turbulent properties of internal waves in the South China Sea. Oceanography 24, 78–87 (2011)

Download references

Acknowledgements

This article is dedicated to the memory of author T.-Y. Tang. Our work was supported by the US Office of Naval Research and the Taiwan National Science Council. We are indebted to the captains and crew of all of the research vessels that supported this work, as well as to the technical staff of the seagoing institutions. Without the skill and hard work of all of these people, these observations would not have been possible.

Author information

Author notes

    • David M. Farmer

    Present address: School of Earth and Ocean Sciences, University of Victoria, British Columbia V8P 5C, Canada.

Affiliations

  1. Scripps Institution of Oceanography, University of California San Diego, La Jolla, California 92037, USA

    • Matthew H. Alford
    • , Jennifer A. MacKinnon
    • , Luca R. Centurioni
    • , T. M. Shaun Johnston
    • , Ruth Musgrave
    • , Robert Pinkel
    •  & Daniel L. Rudnick
  2. University of Washington, Seattle, Washington 98105, USA

    • Matthew H. Alford
    • , Ren-Chieh Lien
    • , Andrew I. Pickering
    •  & Luc Rainville
  3. Massachusetts Institute of Technology (MIT), Cambridge, Massachusetts 02139, USA

    • Thomas Peacock
    •  & Andrew I. Pickering
  4. Oregon State University, Corvallis, Oregon 97370, USA

    • Jonathan D. Nash
    •  & James N. Moum
  5. University of Southern Mississippi, Stennis Space Center, Mississippi 39529, USA

    • Maarten C. Buijsman
  6. University of Maryland, Cambridge, Maryland 21613, USA

    • Shenn-Yu Chao
  7. Institute of Oceanography, National Taiwan University, Taipei 10617, Taiwan

    • Ming-Huei Chang
    • , Sen Jan
    • , Joe Wang
    • , Yiing J. Yang
    •  & Tswen-Yung (David) Tang
  8. University of Rhode Island, Rhode Island 02882, USA

    • David M. Farmer
  9. Stanford University, Stanford, California 94305, USA

    • Oliver B. Fringer
  10. National Sun-Yat Sen University, Kaohsiung 80424, Taiwan

    • Ke-Hsien Fu
    • , I-Huan Lee
    •  & Yu-Huai Wang
  11. Naval Research Laboratories (NRL), Stennis Space Center, Mississippi 39529, USA

    • Patrick C. Gallacher
    •  & Dong S. Ko
  12. University of Miami, Miami, Florida 33149, USA

    • Hans C. Graber
  13. Woods Hole Oceanographic Institution, Falmouth, Massachusetts 02543, USA

    • Karl R. Helfrich
    •  & Louis C. St Laurent
  14. Florida Institute of Technology, Melbourne, Florida 32901, USA

    • Steven M. Jachec
  15. Global Ocean Associates, Alexandria, Virginia 22310, USA

    • Christopher R. Jackson
  16. University of Victoria, Victoria, British Columbia V8W 3P6, Canada

    • Jody M. Klymak
  17. Princeton University, New Jersey 08542, USA

    • Sonya Legg
  18. Institut de Mécanique des Fluides de Toulouse, Toulouse 31400, France

    • Matthieu J. Mercier
  19. Korea Institute of Ocean Science and Technology, Ansan 426–744, South Korea

    • Jae-Hun Park
  20. Soliton Ocean Services, Carmel, California 93924, USA

    • Steven R. Ramp
  21. University of California San Diego, La Jolla, California 92037, USA

    • Sutanu Sarkar
  22. University of North Carolina, Chapel Hill, North Carolina 25599, USA

    • Alberto Scotti
  23. University of Alaska at Fairbanks, Fairbanks, Alaska 99775, USA

    • Harper L. Simmons
  24. Colorado State University, Fort Collins, Colorado 80523, USA

    • Subhas K. Venayagamoorthy
  25. Office of Naval Research, Arlington, Virginia, USA

    • Theresa Paluszkiewicz

Authors

  1. Search for Matthew H. Alford in:

  2. Search for Thomas Peacock in:

  3. Search for Jennifer A. MacKinnon in:

  4. Search for Jonathan D. Nash in:

  5. Search for Maarten C. Buijsman in:

  6. Search for Luca R. Centurioni in:

  7. Search for Shenn-Yu Chao in:

  8. Search for Ming-Huei Chang in:

  9. Search for David M. Farmer in:

  10. Search for Oliver B. Fringer in:

  11. Search for Ke-Hsien Fu in:

  12. Search for Patrick C. Gallacher in:

  13. Search for Hans C. Graber in:

  14. Search for Karl R. Helfrich in:

  15. Search for Steven M. Jachec in:

  16. Search for Christopher R. Jackson in:

  17. Search for Jody M. Klymak in:

  18. Search for Dong S. Ko in:

  19. Search for Sen Jan in:

  20. Search for T. M. Shaun Johnston in:

  21. Search for Sonya Legg in:

  22. Search for I-Huan Lee in:

  23. Search for Ren-Chieh Lien in:

  24. Search for Matthieu J. Mercier in:

  25. Search for James N. Moum in:

  26. Search for Ruth Musgrave in:

  27. Search for Jae-Hun Park in:

  28. Search for Andrew I. Pickering in:

  29. Search for Robert Pinkel in:

  30. Search for Luc Rainville in:

  31. Search for Steven R. Ramp in:

  32. Search for Daniel L. Rudnick in:

  33. Search for Sutanu Sarkar in:

  34. Search for Alberto Scotti in:

  35. Search for Harper L. Simmons in:

  36. Search for Louis C. St Laurent in:

  37. Search for Subhas K. Venayagamoorthy in:

  38. Search for Yu-Huai Wang in:

  39. Search for Joe Wang in:

  40. Search for Yiing J. Yang in:

  41. Search for Theresa Paluszkiewicz in:

  42. Search for Tswen-Yung (David) Tang in:

Contributions

All authors contributed to the paper in multiple ways. Primary writing: M.H.A., T. Peacock, J.A.M. & J.D.N. Synthesis and overall coordination: T. Paluszkiewicz & T.-Y.T. Energy flux calculations: M.H.A. & A.I.P. Energy budget calculation: M.H.A., M.C.B., M.-H.C., R.-C.L., J.M.K. & L.C.S.L. Near-field moorings and calculations: M.H.A., A.I.P., L.R., J.D.N., J.N.M. & M.-H.C. Far-field moorings and calculations: L.R.C., M.-H.C., R.-C.L., S.R.R., Y.J.Y. & T.-Y.T. Near-field CTD measurements (Fig. 2d): R.P. & R.M. Near-field lowered acoustic Doppler current profiler measurements: M.H.A., J.D.N., J.A.M., L.R., H.L.S., A.I.P & R.M. Pressure inverted echo sounder measurements: D.M.F., J.-H.P., Y.J.Y. & M.H.A. Microstructure measurements: L.C.S.L., K.-H.F., H.L.S. & Y.-H.W. Remote sensing: C.R.J. & H.C.G. Theory: K.R.H. & D.M.F. Glider measurements: T.M.S.J. & D.L.R. Regional contextualization and logistical support: S.-Y.C., I-H.L., S.R.R., J.W., Y.J.Y. & T.-Y.T. Far-field modelling: S.J. & H.L.S. Two-dimensional modelling: J.M.K., S.S., S.M.J., A.S., R.M. & K.V. Near-field modelling: M.C.B., O.B.F., S.L. & S.M.J. Kuroshio modelling: P.C.G., S.J. & D.S.K. Laboratory measurements: T. Peacock & M.J.M.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to Matthew H. Alford.

Extended data

About this article

Publication history

Received

Accepted

Published

DOI

https://doi.org/10.1038/nature14399

Further reading

Comments

By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.