Improving Estimates of the Antarctic Circumpolar Current Streamlines in Drake Passage

Yueng-Djern Lenn Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California

Search for other papers by Yueng-Djern Lenn in
Current site
Google Scholar
PubMed
Close
,
Teresa K. Chereskin Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California

Search for other papers by Teresa K. Chereskin in
Current site
Google Scholar
PubMed
Close
, and
Janet Sprintall Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California

Search for other papers by Janet Sprintall in
Current site
Google Scholar
PubMed
Close
Restricted access

Abstract

Accurately resolving the mean Antarctic Circumpolar Current (ACC) is essential for determining Southern Ocean eddy fluxes that are important to the global meridional overturning circulation. Previous estimates of the mean ACC have been limited by the paucity of Southern Ocean observations. A new estimate of the mean surface ACC in Drake Passage is presented that combines sea surface height anomalies measured by satellite altimetry with a recent dataset of repeat high-resolution acoustic Doppler current profiler observations. A mean streamfunction (surface height field), objectively mapped from the mean currents, is used to validate two recent dynamic height climatologies. The new streamfunction has narrower and stronger ACC fronts separated by quiescent zones of much weaker flow, thereby improving on the resolution of ACC fronts observed in the other climatologies. Distinct streamlines can be associated with particular ACC fronts and tracked in time-dependent maps of dynamic height. This analysis shows that varying degrees of topographic control are evident in the preferred paths of the ACC fronts through Drake Passage.

* Current affiliation: School of Ocean Sciences, Bangor University, Anglesey, Wales, United Kingdom

Corresponding author address: Yueng-Djern Lenn, School of Ocean Sciences, Bangor University, Menai Bridge, Anglesey, LL59 5AB Wales, United Kingdom. Email: yueng@coast.ucsd.edu

Abstract

Accurately resolving the mean Antarctic Circumpolar Current (ACC) is essential for determining Southern Ocean eddy fluxes that are important to the global meridional overturning circulation. Previous estimates of the mean ACC have been limited by the paucity of Southern Ocean observations. A new estimate of the mean surface ACC in Drake Passage is presented that combines sea surface height anomalies measured by satellite altimetry with a recent dataset of repeat high-resolution acoustic Doppler current profiler observations. A mean streamfunction (surface height field), objectively mapped from the mean currents, is used to validate two recent dynamic height climatologies. The new streamfunction has narrower and stronger ACC fronts separated by quiescent zones of much weaker flow, thereby improving on the resolution of ACC fronts observed in the other climatologies. Distinct streamlines can be associated with particular ACC fronts and tracked in time-dependent maps of dynamic height. This analysis shows that varying degrees of topographic control are evident in the preferred paths of the ACC fronts through Drake Passage.

* Current affiliation: School of Ocean Sciences, Bangor University, Anglesey, Wales, United Kingdom

Corresponding author address: Yueng-Djern Lenn, School of Ocean Sciences, Bangor University, Menai Bridge, Anglesey, LL59 5AB Wales, United Kingdom. Email: yueng@coast.ucsd.edu

Save
  • Botnikov, V. N., 1963: Geographical position of the Antarctic Convergence Zone in the Southern Ocean. Inf. Sov. Antarct. Exped., 4 , 324327.

    • Search Google Scholar
    • Export Citation
  • Chereskin, T. K., and A. J. Harding, 1993: Modeling the performance of an acoustic Doppler current profiler. J. Atmos. Oceanic Technol., 10 , 4363.

    • Search Google Scholar
    • Export Citation
  • Chereskin, T. K., and C. L. Harris, 1997: Shipboard acoustic Doppler current profiling during the WOCE Indian Ocean expediton: I10. Tech. Rep. SIO 97-14, Scripps Institution of Oceanography, 137 pp.

  • Conkright, M. E., R. A. Locarnini, H. E. Garcia, T. D. O’Brien, T. P. Boyer, C. Stephens, and J. I. Antonov, 2002: World Ocean Atlas 2001: Objective Analyses, Data Statistics, and Figures, CD-ROM Documentation. National Oceanographic Data Center, 17 pp.

    • 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
  • Davis, R. E., 2005: Intermediate-depth circulation of the Indian and South Pacific Oceans measured by autonomous floats. J. Phys. Oceanogr., 35 , 683707.

    • 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
  • Dong, S., S. T. Gille, and J. Sprintall, 2007: An assessment of the Southern Ocean mixed layer heat budget. J. Climate, 20 , 44254442.

    • 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 , C8. 1947719498.

    • Search Google Scholar
    • Export Citation
  • Egbert, G. D., A. F. Bennet, and M. Foreman, 1994: TOPEX/Poseidon tide estimates using a global inverse model. J. Geophys. Res., 99 , 2482124852.

    • Search Google Scholar
    • Export Citation
  • Gille, S. T., 1994: Mean sea surface height of the Antarctic Circumpolar Current from Geosat data: Method and application. J. Geophys. Res., 99 , C9. 1825518273.

    • Search Google Scholar
    • Export Citation
  • Gille, S. T., 2003a: Float observations of the Southern Ocean. Part I: Estimating mean fields, bottom velocities, and topographic steering. J. Phys. Oceanogr., 33 , 11671182.

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

  • 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
  • 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
  • Lenn, Y. D., 2006: Observations of Antarctic Circumpolar Current Dynamics in the Drake Passage and small-scale variability near the Antarctic Peninsula. Ph.D. thesis, Scripps Institution of Oceanography, University of California, San Diego, 136 pp.

  • 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 in Drake Passage. J. Mar. Res., 65 , 2758.

    • Search Google Scholar
    • Export Citation
  • Le Traon, P. Y., F. Nadal, and N. Ducet, 1998: An improved mapping method of multisatellite altimeter data. J. Atmos. Oceanic Technol., 15 , 522534.

    • Search Google Scholar
    • Export Citation
  • Maximenko, N., and P. P. Niiler, 2005: Hybrid decade-mean global sea level with mesoscale resolution. Recent Advances in Marine Science and Technology, N. Saxena, Ed., PACON International, 55–59.

    • Search Google Scholar
    • Export Citation
  • Niiler, P. P., N. A. Maximenko, and J. C. McWilliams, 2003: Dynamically balanced absolute sea level of the global ocean derived from near-surface velocity observations. Geophys. Res. Lett., 30 .2164, doi:10.1029/2003GL018628.

    • Search Google Scholar
    • Export Citation
  • Olbers, D., V. Gouretski, G. Seiß, and J. Schröter, 1992: Hydrographic Atlas of the Southern Ocean. Alfred Wegener Institut, 17 pp. and 82 plates.

    • 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, 2002: A mean synoptic view of the Subantarctic Front south of Australia. J. Phys. Oceanogr., 32 , 15361553.

    • Search Google Scholar
    • Export Citation
  • Rintoul, S., and S. Sokolov, 2001: Baroclinic transport variability of the Antarctic Circumpolar Current south of Australia (WOCE repeat section SR3). J. Geophys. Res., 106 , C2. 28152832.

    • 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
  • Seidler, G., M. Rouault, and J. R. E. Lutjeharms, 2006: Structure and origin of the subtropical South Indian Ocean Countercurrent. Geophys. Res. Lett., 33 .L24609, doi:10.1029/2006GL027399.

    • Search Google Scholar
    • Export Citation
  • Sokolov, S., and S. R. Rintoul, 2002: Structure of the Southern Ocean fronts at 140°E. J. Mar. Syst., 37 , 151184.

  • Sokolov, S., and S. R. 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.

  • Tokinaga, H., Y. Tanimoto, and S-P. Xie, 2005: SST-induced surface wind variation over the Brazil–Malvinas Confluence: Satellite and in situ observations. J. Climate, 18 , 34703482.

    • Search Google Scholar
    • Export Citation
All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 193 91 5
PDF Downloads 69 21 1