• Alford, M., , and M. Gregg, 2000: Near-inertial mixing: Modulation of shear, strain and microstructure at low latitude. J. Geophys. Res., in press.

    • Search Google Scholar
    • Export Citation
  • Bell, T. H. Jr, . 1975: Topographically generated internal waves in the open ocean. J. Geophys. Res, 80 , 320327.

  • D'Asaro, E. A., 1985: The energy flux from the wind to near-inertial motions in the mixed layer. J. Phys. Oceanogr, 15 , 943959.

  • D'Asaro, E. A., 1989: The decay of wind-forced mixed layer inertial oscillations due to the β effect. J. Geophys. Res, 94 , 20452056.

    • Search Google Scholar
    • Export Citation
  • D'Asaro, E. A., , C. E. Eriksen, , M. D. Levine, , P. Niiler, , C. A. Paulson, , and P. V. Meurs, 1995: Upper-ocean inertial currents forced by a strong storm. Part I: Data and comparisons with linear theory. J. Phys. Oceanogr, 25 , 29092936.

    • Search Google Scholar
    • Export Citation
  • Egbert, G. D., 1997: Tidal data inversion: Interpolation and inference. Progress in Oceanography, Vol. 40, Pergamon, 53–80.

  • Egbert, G. D., , and R. D. Ray, 2000: Significant dissipation of tidal energy in the deep ocean inferred from satellite altimeter data. Nature, 45 (6,) 775778.

    • Search Google Scholar
    • Export Citation
  • Garrett, C., 2001: What is the “near-inertial” band and why is it different from the rest of the internal wave spectrum? J. Phys. Oceanogr, 31 , 962971.

    • Search Google Scholar
    • Export Citation
  • Henyey, F. S., , J. Wright, , and S. M. Flatté, 1986: Energy and action flow through the internal wave field. J. Geophys. Res, 91 , 84878495.

    • Search Google Scholar
    • Export Citation
  • Hibiya, T., , M. Nagasawa, , and Y. Niwa, 1999: Model predicted distribution of internal wave energy for diapycnal mixing processes in the deep waters of the North Pacific. Dynamics of Oceanic Internal Gravity Waves: Proc.'Aha Huliko'a Hawaiian Winter Workshop, P. Müller and D. Henderson, Eds., Hawaii Institute of Geophysics, 205–215.

    • Search Google Scholar
    • Export Citation
  • Kalnay, E. M., and Coauthors,. . 1996: The NCEP/NCAR 40-Year Reanalysis Project. Bull. Amer. Meteor. Soc, 77 , 437471.

  • Kantha, L., , and C. Tierney, 1997: Global baroclinic tides. Progress in Oceanography, Vol. 40, Pergamon, 163–178.

  • Kunze, E., , R. W. Schmitt, , and J. M. Toole, 1995: The energy balance in a warm-core ring's near-inertial critical layer. J. Phys. Oceanogr, 25 , 942957.

    • Search Google Scholar
    • Export Citation
  • Large, W. G., , and S. Pond, 1981: Open ocean momentum flux measurements in moderate to strong winds. J. Phys. Oceanogr, 11 , 324336.

  • Levitus, S., , and T. Boyer, 1994: World Ocean Atlas 1994. Vol. 4: Temperature, NOAA Atlas NESDIS 4, 117 pp.

  • McDermott, D. A., , D. E. Harrison, , and N. K. Larkin, 1997: An intercomparison of near-surface wind products over the ocean on monthly mean and longer time scales, 1985–1995. NOAA Tech. Memo. ERL PMEL-110, 163 pp.

    • Search Google Scholar
    • Export Citation
  • Morozov, E. G., 1995: Semidiurnal internal wave global field. Deep-Sea Res, 42 , 135148.

  • Munk, W. H., 1966: Abyssal recipes. Deep-Sea Res, 13 , 707730.

  • Munk, W. H., , and C. Wunsch, 1998: Abyssal recipes II: Energetics of tidal and wind mixing. Deep-Sea Res, 45 , 19772010.

  • Nilsson, J., 1995: Energy flux from travelling hurricanes to the internal wave field. J. Phys. Oceanogr, 25 , 558573.

  • Paduan, J. D., , R. A. de Soerke, , and R. A. Weller, 1989: Inertial oscillations in the upper ocean during the Mixed Layer Dynamics Experiment (MILDEX). J. Geophys. Res, 94 , 48354842.

    • Search Google Scholar
    • Export Citation
  • Pollard, R. T., 1980: Properties of near-surface inertial oscillations. J. Phys. Oceanogr, 10 , 385398.

  • Pollard, R. T., , and R. C. Millard, 1970: Comparison between observed and simulated wind-generated inertial oscillations. Deep-Sea Res, 17 , 153175.

    • Search Google Scholar
    • Export Citation
  • Polzin, K. L., , J. M. Toole, , J. R. Ledwell, , and R. W. Schmitt, 1997: Spatial variability of turbulent mixing in the abyssal ocean. Science, 276 , 9396.

    • Search Google Scholar
    • Export Citation
  • Sjöberg, B., , and A. Stigebrandt, 1992: Computations of the geographical distribution of the energy flux to mixing processes via internal tides and the associated vertical circulation in the ocean. Deep-Sea Res, 39 , 269291.

    • Search Google Scholar
    • Export Citation
  • Swail, V. R., , and A. T. Cox, 2000: On the use of NCEP–NCAR reanalysis surface marine wind fields for a long-term North Atlantic wave hindcast. J. Atmos. Oceanic Technol, 17 , 532545.

    • Search Google Scholar
    • Export Citation
  • Thomson, R., , and W. Huggett, 1981: Wind-driven inertial oscillations of large spatial coherence. Atmos.–Ocean, 19 , 281306.

  • Wunsch, C., 1998: The work done by the wind on the oceanic general circulation. J. Phys. Oceanogr, 28 , 23322340.

All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 419 419 31
PDF Downloads 216 216 31

Internal Swell Generation: The Spatial Distribution of Energy Flux from the Wind to Mixed Layer Near-Inertial Motions

View More View Less
  • 1 Applied Physics Laboratory and School of Oceanography, University of Washington, Seattle, Washington
© Get Permissions Rent on DeepDyve
Restricted access

Abstract

The energy flux from the wind to inertial mixed layer motions is computed for all oceans from 50°S to 50°N for the years 1996–99. The wind stress, τ, is computed from 6-h, 2.5°-resolution NCEP–NCAR global reanalysis surface winds. The inertial mixed layer response, uI, and the energy flux, Π = τ · uI, are computed using a slab model. The validity of the reanalysis winds and the slab model is demonstrated by direct comparison with wind and ADCP velocity records from NDBC buoys. (At latitudes > 50°, the inertial response is too fast to be resolved by the reanalysis wind 6-h output interval.)

Midlatitude storms produce the greatest fluxes, resulting in broad maxima near 40° latitude during each hemisphere's winter, concentrated in the western portion of each basin. Northern Hemisphere fluxes exceed those in the Southern Hemisphere by about 50%. The global mean energy flux from 1996 to 1999 and 50°S to 50°N is (0.98 ± 0.08) × 10−3 W m−2, for a total power of 0.29 TW (1 TW = 1012 W). This total is the same order of magnitude as recent estimates of the global power input to baroclinic M2 tidal motions, suggesting that wind-generated near-inertial waves may play an important role in the global energy balance.

Corresponding author address: Dr. Matthew H. Alford, Ocean Physics Dept., Applied Physics Laboratory, University of Washington, 1013 NE 40th St., Seattle, WA 98105-6698.Email: malford@apl.washington.edu

Abstract

The energy flux from the wind to inertial mixed layer motions is computed for all oceans from 50°S to 50°N for the years 1996–99. The wind stress, τ, is computed from 6-h, 2.5°-resolution NCEP–NCAR global reanalysis surface winds. The inertial mixed layer response, uI, and the energy flux, Π = τ · uI, are computed using a slab model. The validity of the reanalysis winds and the slab model is demonstrated by direct comparison with wind and ADCP velocity records from NDBC buoys. (At latitudes > 50°, the inertial response is too fast to be resolved by the reanalysis wind 6-h output interval.)

Midlatitude storms produce the greatest fluxes, resulting in broad maxima near 40° latitude during each hemisphere's winter, concentrated in the western portion of each basin. Northern Hemisphere fluxes exceed those in the Southern Hemisphere by about 50%. The global mean energy flux from 1996 to 1999 and 50°S to 50°N is (0.98 ± 0.08) × 10−3 W m−2, for a total power of 0.29 TW (1 TW = 1012 W). This total is the same order of magnitude as recent estimates of the global power input to baroclinic M2 tidal motions, suggesting that wind-generated near-inertial waves may play an important role in the global energy balance.

Corresponding author address: Dr. Matthew H. Alford, Ocean Physics Dept., Applied Physics Laboratory, University of Washington, 1013 NE 40th St., Seattle, WA 98105-6698.Email: malford@apl.washington.edu

Save