• Botnikov, V. N., 1963: Geographical position of the Antarctic convergence zone in the Southern Ocean. Sov. Antarct. Exped. Inf. Bull., 4, 324327.

    • Search Google Scholar
    • Export Citation
  • Bryden, H. L., 1979: Poleward heat flux and conversion of available potential energy in Drake Passage. J. Mar. Res., 37, 122.

  • Bryden, H. L., and R. Heath, 1985: Energetic eddies at the northern edge of the Antarctic Circumpolar Current in the southwest Pacific. Prog. Oceanogr., 14, 6587.

    • Search Google Scholar
    • Export Citation
  • Cerovečki, I. R., R. A. Plumb, and W. Heres, 2009: Eddy transport and mixing in a wind- and buoyancy-driven jet on a sphere. J. Phys. Oceanogr., 39, 11331149.

    • Search Google Scholar
    • Export Citation
  • Chelton, D., M. Schlax, M. Freilich, and R. Milliff, 2004: Satellite measurements reveal persistent small-scale features in ocean winds. Science, 303, 978983.

    • Search Google Scholar
    • Export Citation
  • Cunningham, S. A., S. G. Alderson, B. A. King, and M. A. Brandon, 2003: Transport and variability of the Antarctic Circumpolar Current in Drake Passage. J. Geophys. Res., 108, 8084, doi:10.1029/2001JC001147.

    • Search Google Scholar
    • Export Citation
  • de Szoeke, R. A., and M. D. Levine, 1981: The advective flux of heat by mean geostrophic motions in the Southern Ocean. Deep-Sea Res., 28A, 10571085.

    • Search Google Scholar
    • Export Citation
  • Drijfhout, S. S., 2005: What sets the surface eddy mass flux in the Southern Ocean? J. Phys. Oceanogr., 35, 21522166.

  • Dukowicz, J. K., and R. D. Smith, 1994: Implicit free-surface method for the Bryan-Cox-Semtner ocean model. J. Geophys. Res., 99 (C4), 79918014.

    • Search Google Scholar
    • Export Citation
  • Dukowicz, J. K., R. D. Smith, and R. C. Malone, 1993: A reformulation and implementation of the Bryan–Cox–Semtner ocean model on the Connection Machine. J. Atmos. Oceanic Technol., 10, 195208.

    • Search Google Scholar
    • Export Citation
  • Egbert, G. D., A. F. Bennet, and M. Foreman, 1994: TOPEX/Poseidon tides estimates using a global inverse model. J. Geophys. Res., 99, 24 82124 852.

    • Search Google Scholar
    • Export Citation
  • Gille, S. T., 2002: Warming of the Southern Ocean since the 1950s. Science, 295, 12751277.

  • Gille, S. T., 2003a: Float observations of the Southern Ocean. Part I: Estimating mean fields, bottom velocities, and topographic steering. J. Phys. Oceanogr., 33, 11671181.

    • Search Google Scholar
    • Export Citation
  • Gille, S. T., 2003b: Float observations of the Southern Ocean. Part II: Eddy fluxes. J. Phys. Oceanogr., 33, 11821196.

  • Gille, S. T., 2005: Statistical characterization of zonal and meridional wind stress. J. Atmos. Oceanic Technol., 22, 13531372.

  • Gnanadesikan, A., 1999: A simple predictive model for the structure of the oceanic pycnocline. Science, 283, 20772079, doi:10.1126/science.283.5410.2077.

    • Search Google Scholar
    • Export Citation
  • Griesel, A., S. T. Gille, J. Sprintall, J. L. McClean, and M. E. Maltrud, 2009: Assessing eddy heat flux and its parameterization: A wavenumber perspective from a 1/10° ocean simulation. Ocean Modell., 29, 248260.

    • Search Google Scholar
    • Export Citation
  • Holland, M. M., and C. M. Bitz, 2003: Polar amplification of climate change in coupled models. Climate Dyn., 21, 221232, doi:10.1007/s00382-003-0332-6.

    • Search Google Scholar
    • Export Citation
  • Hughes, C. W., 2005: Nonlinear vorticity balance of the Antarctic Circumpolar Current. J. Geophys. Res., 110, C11008, doi:10.1029/2004JC002753.

    • Search Google Scholar
    • Export Citation
  • Hughes, C. W., and E. R. Ash, 2001: Eddy forcing of the mean flow in the Southern Ocean. J. Geophys. Res., 106 (C2), 27132722.

  • Jayne, S. R., and J. Marotzke, 2002: The oceanic eddy heat transport. J. Phys. Oceanogr., 32, 33283345.

  • Johnson, G. C., and H. L. Bryden, 1989: On the size of the Antarctic Circumpolar Current. Deep-Sea Res., 36, 3953.

  • Joyce, T. M., W. Zenk, and J. Toole, 1978: The anatomy of the Antarctic Polar Front in Drake Passage. J. Geophys. Res., 83, 60936114.

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

  • Karsten, R. H., and J. Marshall, 2002: Constructing the residual circulation of the ACC from observations. J. Phys. Oceanogr., 32, 33153327.

    • Search Google Scholar
    • Export Citation
  • Killworth, P. D., and C. W. Hughes, 2002: The Antarctic Circumpolar Current as a free equivalent-barotropic jet. J. Mar. Res., 60, 1945.

    • Search Google Scholar
    • Export Citation
  • Large, W. G., J. C. McWilliams, and S. C. Doney, 1994: Oceanic vertical mixing: A review and a model with a nonlocal boundary layer parameterization. Rev. Geophys., 32, 363403.

    • Search Google Scholar
    • Export Citation
  • Lenn, Y.-D., and T. K. Chereskin, 2009: Observations of Ekman currents in the Southern Ocean. J. Phys. Oceanogr., 39, 768779.

  • Lenn, Y.-D., T. K. Chereskin, J. Sprintall, and E. Firing, 2007: Mean jets, mesoscale variability and eddy momentum fluxes in the surface layer of the Antarctic Circumpolar Current. J. Mar. Res., 65, 2758.

    • Search Google Scholar
    • Export Citation
  • Lenn, Y.-D., T. K. Chereskin, and J. Sprintall, 2008: Improving estimates of the Antarctic Circumpolar Current streamlines in Drake Passage. J. Phys. Oceanogr., 38, 10001010.

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

  • Maltrud, M. E., and J. L. McClean, 2005: An eddy-resolving global 1/10° ocean simulation. Ocean Modell., 8 (1–2), 3154.

  • Maltrud, M. E., R. Smith, A. J. Semtner, and R. C. Malone, 1998: Global eddy-resolving ocean simulations driven by 1985–1995 atmospheric winds. J. Geophys. Res., 103, 825830.

    • Search Google Scholar
    • Export Citation
  • Marshall, J., D. Olbers, H. Ross, and D. Wolf-Gladrow, 1993: Potential vorticity constraints on the dynamics and hydrography of the Southern Ocean. J. Phys. Oceanogr., 23, 465487.

    • Search Google Scholar
    • Export Citation
  • McClean, J. L., M. E. Maltrud, and F. O. Bryan, 2006: Measures of fidelity of eddying ocean models. Oceanography, 19, 104117.

  • McClean, J. L., S. Jayne, M. E. Maltrud, and D. P. Ivanova, 2008: The fidelity of ocean models with explicit eddies. Ocean Modeling in an Eddying Regime, Geophys. Monogr., Vol. 177, Amer. Geophys. Union, 149–163.

    • Search Google Scholar
    • Export Citation
  • Morrow, R., R. Coleman, J. Church, and D. Chelton, 1994: Surface eddy momentum flux and velocity variances in the Southern Ocean from Geosat altimetry. J. Phys. Oceanogr., 24, 20502071.

    • Search Google Scholar
    • Export Citation
  • Nowlin W., Jr., S. J. Worley, and T. Whitworth III, 1985: Methods for making point estimates of eddy heat flux as applied to the Antarctic Circumpolar Current. J. Geophys. Res., 90 (C2), 33053324.

    • Search Google Scholar
    • Export Citation
  • Olbers, D., 1998: Comments on “On the obscurantist physics of ‘form drag’ in theorizing about the circumpolar current.” J. Phys. Oceanogr., 28, 16471654.

    • Search Google Scholar
    • Export Citation
  • Olbers, D., 2005: On the role of eddy mixing in the transport of zonal ocean currents. Marine Turbulence: Theories, Observations and Models, H. Z. Baumert, J. H. Simpson, and J. Sündermann, Eds., Cambridge University Press, 511–529.

    • Search Google Scholar
    • Export Citation
  • O’Neill, L. W., D. Chelton, and S. Ebensen, 2003: Observations of SST-induced perturbations of the wind stress field over the Southern Ocean on seasonal timescales. J. Climate, 16, 23402354.

    • Search Google Scholar
    • Export Citation
  • Orsi, A. H., T. Whitworth III, and W. D. Nowlin Jr., 1995: On the meridional extent and fronts of the Antarctic Circumpolar Current. Deep-Sea Res. I, 42, 641673.

    • Search Google Scholar
    • Export Citation
  • Phillips, H. E., and S. Rintoul, 2000: Eddy variability and energetics from direct current measurements in the Antarctic Circumpolar Current south of Australia. J. Phys. Oceanogr., 30, 30503076.

    • Search Google Scholar
    • Export Citation
  • Rhines, P. B., and W. R. Holland, 1979: A theoretical discussion of eddy-driven mean flows. Dyn. Atmos. Oceans, 3, 289325.

  • Rossow, W., and R. A. Schiffer, 1991: ISCCP cloud data products. Bull. Amer. Meteor. Soc., 72, 220.

  • Sciremammano, F., Jr., R. Pillsbury, W. D. Nowlin Jr., and T. Whitworth III, 1980: Spatial scales of temperature and flow in Drake Passage. J. Geophys. Res., 85 (C7), 40154028.

    • Search Google Scholar
    • Export Citation
  • Smith, R. D., J. K. Dukowicz, and R. C. Malone, 1992: Parallel ocean general circulation modeling. Physica D, 60, 3861.

  • Sokolov, S., and S. Rintoul, 2007: Multiple jets of the Antarctic Circumpolar Current south of Australia. J. Phys. Oceanogr., 37, 13941412.

    • Search Google Scholar
    • Export Citation
  • Sprintall, J., 2003: Seasonal to interannual upper-ocean variability in the Drake Passage. J. Mar. Res., 61, 2557.

  • Sprintall, J., 2008: Long-term trends and interannual variability of temperature in the Drake Passage. Prog. Oceanogr., 77, 316330.

  • Stammer, D., 1998: On eddy characteristics, eddy transports, and mean flow properties. J. Phys. Oceanogr., 28, 727739.

  • Stammer, D., and J. Theiss, 2004: Velocity statistics inferred from the TOPEX/Poseidon-Jason-1 tandem mission data. Mar. Geod., 27, 551575.

    • Search Google Scholar
    • Export Citation
  • Stevens, D. P., and V. O. Ivchenko, 1997: The zonal momentum balance in an eddy-resolving general-circulation model of the Southern Ocean. Quart. J. Roy. Meteor. Soc., 123, 929951.

    • Search Google Scholar
    • Export Citation
  • Stroeve, J., M. M. Holland, W. Meier, T. Scambos, and M. Serreze, 2007: Arctic sea ice decline: Faster than forecast. Geophys. Res. Lett., 34, L09501, doi:10.1029/2007GL029703.

    • Search Google Scholar
    • Export Citation
  • Thompson, A. F., 2008: The atmospheric ocean: Eddies and jets in the Antarctic Circumpolar Current. Philos. Trans. Roy. Soc. London, 366A, 45294541.

    • Search Google Scholar
    • Export Citation
  • Vaughan, D. G., and Coauthors, 2003: Recent rapid regional climate warming on the Antarctic Peninsula. Climate Change, 60, 243274, doi:10.1023/A:1026021217991.

    • Search Google Scholar
    • Export Citation
  • Walkden, G. J., K. J. Heywood, and D. P. Stevens, 2008: Eddy heat fluxes from direct current measurements of the Antarctic Polar Front in Shag Rocks Passage. Geophys. Res. Lett., 35, L06602, doi:10.1029/2007GL032767.

    • Search Google Scholar
    • Export Citation
  • Wilson, C., and R. G. Williams, 2004: Why are eddy fluxes of potential vorticity difficult to parameterize? J. Phys. Oceanogr., 34, 142155.

    • Search Google Scholar
    • Export Citation
  • Wolfe, C. L., and P. Cessi, 2010: What sets the strength of the mid-depth stratification and overturning circulation in eddying ocean models? J. Phys. Oceanogr., 40, 15201538.

    • Search Google Scholar
    • Export Citation
  • Xie, P., and P. Arkin, 1998: Global monthly precipitation estimates from satellite-observed outgoing longwave radiation. J. Climate, 11, 137164.

    • Search Google Scholar
    • Export Citation
All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 117 88 0
PDF Downloads 75 52 0

Near-Surface Eddy Heat and Momentum Fluxes in the Antarctic Circumpolar Current in Drake Passage

View More View Less
  • 1 School of Ocean Sciences, Bangor University, Menai Bridge, United Kingdom
  • | 2 Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California
Restricted access

Abstract

The authors present new estimates of the eddy momentum and heat fluxes from repeated high-resolution upper-ocean velocity and temperature observations in Drake Passage and interpret their role in the regional Antarctic Circumpolar Current (ACC) momentum balance. The observations span 7 yr and are compared to eddy fluxes estimated from a 3-yr set of output archived from an eddy-resolving global Parallel Ocean Program (POP) numerical simulation. In both POP and the observations, the stream-averaged cross-stream eddy momentum fluxes correspond to forcing consistent with both a potential vorticity flux into the axis of the Subantarctic Front (SAF) and a sharpening of all three main ACC fronts through Drake Passage. Further, the POP analysis indicates that the mean momentum advection terms reflect the steering of the mean ACC fronts and are not fully balanced by the eddy momentum forcing, which instead impacts the strength and number of ACC fronts.

The comparison between POP and observed eddy heat fluxes was less favorable partly because of model bias in the water mass stratification. Observed cross-stream eddy heat fluxes are generally surface intensified and poleward in the ACC fronts, with values up to approximately −290 ± 80 kW m−2 in the Polar and Southern ACC Fronts. Interfacial form stresses FT, derived from observed eddy heat fluxes in the SAF, show little depth dependence below the Ekman layer. Although FT appears to balance the surface wind stress directly, the estimated interfacial form stress divergence is only an order of magnitude greater than the eddy momentum forcing in the SAF. Thus, although the eddy momentum forcing is of secondary importance in the momentum balance, its effect is not entirely negligible.

Corresponding author address: Yueng-Djern Lenn, School of Ocean Sciences, Bangor University, Menai Bridge, Anglesey LL59 5AB, United Kingdom. E-mail: y.lenn@bangor.ac.uk

Abstract

The authors present new estimates of the eddy momentum and heat fluxes from repeated high-resolution upper-ocean velocity and temperature observations in Drake Passage and interpret their role in the regional Antarctic Circumpolar Current (ACC) momentum balance. The observations span 7 yr and are compared to eddy fluxes estimated from a 3-yr set of output archived from an eddy-resolving global Parallel Ocean Program (POP) numerical simulation. In both POP and the observations, the stream-averaged cross-stream eddy momentum fluxes correspond to forcing consistent with both a potential vorticity flux into the axis of the Subantarctic Front (SAF) and a sharpening of all three main ACC fronts through Drake Passage. Further, the POP analysis indicates that the mean momentum advection terms reflect the steering of the mean ACC fronts and are not fully balanced by the eddy momentum forcing, which instead impacts the strength and number of ACC fronts.

The comparison between POP and observed eddy heat fluxes was less favorable partly because of model bias in the water mass stratification. Observed cross-stream eddy heat fluxes are generally surface intensified and poleward in the ACC fronts, with values up to approximately −290 ± 80 kW m−2 in the Polar and Southern ACC Fronts. Interfacial form stresses FT, derived from observed eddy heat fluxes in the SAF, show little depth dependence below the Ekman layer. Although FT appears to balance the surface wind stress directly, the estimated interfacial form stress divergence is only an order of magnitude greater than the eddy momentum forcing in the SAF. Thus, although the eddy momentum forcing is of secondary importance in the momentum balance, its effect is not entirely negligible.

Corresponding author address: Yueng-Djern Lenn, School of Ocean Sciences, Bangor University, Menai Bridge, Anglesey LL59 5AB, United Kingdom. E-mail: y.lenn@bangor.ac.uk
Save