Editorial Type:
Article
Article Type:
Research Article

Tracing Southwest Pacific Bottom Water Using Potential Vorticity and Helium-3

Stephanie M. Downes Program in Atmospheric and Oceanic Sciences, Princeton University, New Jersey, and Research School of Earth Sciences, and ARC Centre of Excellence for Climate System Science, The Australian National University, Acton, Australian Capital Territory, Australia

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Robert M. Key Program in Atmospheric and Oceanic Sciences, Princeton University, Princeton, New Jersey

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Alejandro H. Orsi Department of Oceanography, Texas A&M University, College Station, Texas

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Kevin G. Speer Department of Oceanography, The Florida State University, Tallahassee, Florida

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James H. Swift Scripps Institution of Oceanography, La Jolla, California

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Print Publication:
01 Dec 2012
DOI:
https://doi.org/10.1175/JPO-D-12-019.1
Page(s):
2153–2168
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Abstract

This study uses potential vorticity and other tracers to identify the pathways of the densest form of Circumpolar Deep Water in the South Pacific, termed “Southwest Pacific Bottom Water” (SPBW), along the 28.2 kg m−3 surface. This study focuses on the potential vorticity signals associated with three major dynamical processes occurring in the vicinity of the Pacific–Antarctic Ridge: 1) the strong flow of the Antarctic Circumpolar Current (ACC), 2) lateral eddy stirring, and 3) heat and stratification changes in bottom waters induced by hydrothermal vents. These processes result in southward and downstream advection of low potential vorticity along rising isopycnal surfaces. Using δ3He released from the hydrothermal vents, the influence of volcanic activity on the SPBW may be traced across the South Pacific along the path of the ACC to Drake Passage. SPBW also flows within the southern limb of the Ross Gyre, reaching the Antarctic Slope in places and contributes via entrainment to the formation of Antarctic Bottom Water. Finally, it is shown that the magnitude and location of the potential vorticity signals associated with SPBW have endured over at least the last two decades, and that they are unique to the South Pacific sector.

Corresponding author address: Stephanie Downes, Research School of Earth Sciences, The Australian National University, Canberra ACT 0200, Australia.E-mail: stephanie.downes@anu.edu.au

Abstract

This study uses potential vorticity and other tracers to identify the pathways of the densest form of Circumpolar Deep Water in the South Pacific, termed “Southwest Pacific Bottom Water” (SPBW), along the 28.2 kg m−3 surface. This study focuses on the potential vorticity signals associated with three major dynamical processes occurring in the vicinity of the Pacific–Antarctic Ridge: 1) the strong flow of the Antarctic Circumpolar Current (ACC), 2) lateral eddy stirring, and 3) heat and stratification changes in bottom waters induced by hydrothermal vents. These processes result in southward and downstream advection of low potential vorticity along rising isopycnal surfaces. Using δ3He released from the hydrothermal vents, the influence of volcanic activity on the SPBW may be traced across the South Pacific along the path of the ACC to Drake Passage. SPBW also flows within the southern limb of the Ross Gyre, reaching the Antarctic Slope in places and contributes via entrainment to the formation of Antarctic Bottom Water. Finally, it is shown that the magnitude and location of the potential vorticity signals associated with SPBW have endured over at least the last two decades, and that they are unique to the South Pacific sector.

Corresponding author address: Stephanie Downes, Research School of Earth Sciences, The Australian National University, Canberra ACT 0200, Australia.E-mail: stephanie.downes@anu.edu.au
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  • Assmann, K. A., and R. Timmermann, 2005: Variability of dense water formation in the Ross Sea. Ocean Dyn., 55, 68–87.

  • Bianchi, D., J. L. Sarmiento, A. Gnanadesikan, R. M. Key, P. Schlosser, and R. Newton, 2010: Low helium flux from the mantle inferred from simulations of oceanic helium isotope data. Earth Planet. Sci. Lett., 297, 379–386.

    • Search Google Scholar
    • Export Citation

  • Callahan, J. E., 1972: The structure and circulation of deep water in the Antarctic. Deep-Sea Res., 19, 563–575.

  • Cannon, G. A., and D. J. Pashinski, 1997: Variations in mean currents affecting hydrothermal plumes on the Juan de Fuca Ridge. J. Geophys. Res., 102 (C11), 24 965–24 976.

    • Search Google Scholar
    • Export Citation

  • Che, S., Z. Linlin, and Y. Xiaomei, 2011: Stream-coordinate structure of oceanic jets based on merged altimeter data. Chin. J. Oceanol. Limnol., 29, 1–9.

    • Search Google Scholar
    • Export Citation

  • Clarke, W. B., M. A. Beg, and H. Craig, 1969: Excess 3 he in the sea: Evidence for terrestrial primordial helium. Earth Planet. Sci. Lett., 6, 213–220.

    • Search Google Scholar
    • Export Citation

  • Drijfhout, S. S., and A. C. Naveira Garabato, 2008: The zonal dimension of the Indian Ocean meridional overturning circulation. J. Phys. Oceanogr., 38, 359–379.

    • 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, 18  255–18  273.

    • Search Google Scholar
    • Export Citation

  • Gnanadesikan, A., and R. W. Hallberg, 2000: On the relationship of the circumpolar current to Southern Hemisphere winds in coarse-resolution ocean models. J. Phys. Oceanogr., 30, 2013–2034.

    • Search Google Scholar
    • Export Citation

  • Gordon, A. L., E. Molinelli, and T. Baker, 1978: Large-scale relative dynamic topography of the Southern Ocean. J. Geophys. Res., 83, 3023–3032.

    • Search Google Scholar
    • Export Citation

  • Jackett, D. R., and T. J. McDougall, 1997: A neutral density variable for the world’s oceans. J. Phys. Oceanogr., 27, 237–263.

  • Jacobs, S. S., and C. F. Giulivi, 2010: Large multidecadal salinity trends near the Pacific–Antarctic continental margin. J. Climate, 23, 4508–4524.

    • Search Google Scholar
    • Export Citation

  • Jacobs, S. S., C. F. Giulivi, and P. A. Mele, 2002: Freshening of the Ross Sea during the late 20th century. Science, 297, 386–389.

  • Jenkins, A., P. Dutrieux, S. S. Jacobs, S. D. McPhail, J. R. Perrett, A. T. Webb, and D. White, 2010: Observations beneath Pine Island Glacier in West Antarctica and implications for its retreat. Nat. Geosci., 3, 468–472.

    • Search Google Scholar
    • Export Citation

  • Johnson, G. C., and L. D. Talley, 1997: Deep tracer and dynamical plumes in the tropical Pacific Ocean. J. Geophys. Res., 102, 24 953–24 964.

    • Search Google Scholar
    • Export Citation

  • Joyce, T. M., and K. G. Speer, 1987: Modeling the large-scale influence of geothermal sources on abyssal flow. J. Geophys. Res., 92, 2843–2850.

    • Search Google Scholar
    • Export Citation

  • Joyce, T. M., B. A. Warren, and L. D. Talley, 1986: The geothermal heating of the abyssal subarctic Pacific Ocean. Deep-Sea Res., 33, 1003–1015.

    • Search Google Scholar
    • Export Citation

  • Klinkhammer, G. P., 1980: Observations of the distribution of manganese over the East Pacific rise. Chem. Geol., 29, 211–226.

  • Lu, J., and K. Speer, 2010: Topography, jets, and eddy mixing in the Southern Ocean. J. Mar. Res., 68, 479–502.

  • Lupton, J., 1998: Hydrothermal helium plumes in the Pacific Ocean. J. Geophys. Res., 103, 15 853–15 868.

  • Lupton, J., and H. Craig, 1981: A major Helium-3 source at 15°S on the East Pacific Rise. Science, 214, 13–18.

  • Morgan, W. J., 1971: Convection plumes in the lower mantle. Nature, 230, 42–43.

  • Mortlock, R. A., P. N. Froelich, R. A. Feely, G. J. Massoth, D. A. Butterfield, and J. E. Lupton, 1993: Silica and germanium in Pacific Ocean hydrothermal vents and plumes. Earth Planet. Sci. Lett., 119, 365–378.

    • Search Google Scholar
    • Export Citation

  • Naveira Garabato, A. C., D. P. Stevens, A. J. Watson, and W. Roether, 2007: Short-circuiting of the overturning circulation in the Antarctic Circumpolar Current. Nature, 447, 194–197.

    • Search Google Scholar
    • Export Citation

  • Nikurashin, M., and R. Ferrari, 2011: Global energy conversion rate from geostrophic flows into internal lee waves in the deep ocean. Geophys. Res. Lett., 38, L08610, doi:10.1029/2011GL046576.

    • Search Google Scholar
    • Export Citation

  • Orsi, A. H., 2010: Recycling bottom waters. Nat. Geosci., 3, 307–309.

  • Orsi, A. H., and T. Whitworth III, 2005: Southern Ocean. Vol. 1, Hydrographic Atlas of the World Ocean Circulation Experiment (WOCE), International WOCE Project Office, 223 pp.

  • Orsi, A. H., and C. L. Wiederwohl, 2009: A recount of Ross Sea waters. Deep-Sea Res. II, 56, 778–795.

  • Orsi, A. H., T. Whitworth III, and W. D. Nowlin, 1995: On the meridional extent and fronts of the Antarctic Circumpolar Current. Deep-Sea Res. I, 42, 641–673.

    • Search Google Scholar
    • Export Citation

  • Orsi, A. H., G. Johnson, and J. Bullister, 1999: Circulation, mixing, and production of Antarctic Bottom Water. Prog. Oceanogr., 43, 55–109.

    • Search Google Scholar
    • Export Citation

  • Orsi, A. H., S. S. Jacobs, A. L. Gordon, and M. Visbeck, 2001: Cooling and ventilating the abyssal ocean. Geophys. Res. Lett., 28, 2923–2926.

    • Search Google Scholar
    • Export Citation

  • Orsi, A. H., W. M. Smethie Jr., and J. L. Bullister, 2002: On the total input of Antarctic waters to the deep ocean: A preliminary estimate from chlorofluorocarbon measurements. J. Geophys. Res., 107, C83122, doi:10.1029/2001JC000976.

    • Search Google Scholar
    • Export Citation

  • Patterson, S. L., and T. Whitworth III, 1990: Antarctic sector of the Pacific. Physical Oceanography, G. P. Glasby, Ed., Elsevier Oceanography Series, Vol. 51, Elsevier, 55–93.

  • Read, J. F., R. T. Pollard, and A. I. Morrison, 1995: On the southerly extent of the Antarctic Circumpolar Current in the southeast Pacific. Deep-Sea Res. II, 42, 933–954.

    • Search Google Scholar
    • Export Citation

  • Renault, A., C. Provost, N. Sennéchael, N. Barré, and A. Kartavtseff, 2011: Two full-depth velocity sections in the Drake Passage in 2006–transport estimates. Deep-Sea Res. II, 58, 2572–2591.

    • Search Google Scholar
    • Export Citation

  • Rickard, G. J., M. J. Roberts, M. J. M. Williams, A. Dunn, and M. H. Smith, 2010: Mean circulation and hydrography in the Ross Sea sector, Southern Ocean: Representation in numerical models. Antarct. Sci., 22, 533–558.

    • Search Google Scholar
    • Export Citation

  • Rintoul, S. R., and S. Sokolov, 2001: Baroclinic transport variability of the Antarctic Circumpolar Current south of Australia. J. Geophys. Res., 106 (C2), 2815–2832.

    • Search Google Scholar
    • Export Citation

  • Rintoul, S. R., C. W. Hughes, and D. Olbers, 2001: Ocean circulation and climate. The Antarctic Circumpolar System, Academic Press, 292–294.

  • Rüth, C., R. Well, and W. Roether, 2000: Primordial 3He in South Atlantic deep waters from sources on the mid-Atlantic ridge. Deep-Sea Res. I, 47, 1059–1075.

    • Search Google Scholar
    • Export Citation

  • Sokolov, S., and S. R. Rintoul, 2007: Multiple jets of the Antarctic Circumpolar Current south of Australia. J. Phys. Oceanogr., 37, 1394–1412.

    • Search Google Scholar
    • Export Citation

  • Speer, K. G., and P. A. Rona, 1989: A model of an Atlantic and Pacific hydrothermal plume. J. Phys. Oceanogr., 94, 6213–6220.

  • Speer, K. G., and K. R. Helfrich, 1995: Hydrothermal plumes: A review of flow and fluxes. Physical Oceanography, Geological Society, 373–385.

  • Speer, K. G., S. R. Rintoul, and B. Sloyan, 2000: The diabatic Deacon Cell. J. Phys. Oceanogr., 30, 3212–3222.

  • Srinivasan, A., Z. Garraffo, and M. Iskandarani, 2009: Abyssal circulation in the Indian Ocean from a 1/12° resolution global hindcast. Deep-Sea Res. I, 56, 1907–1926.

    • Search Google Scholar
    • Export Citation

  • Stommel, H., 1982: Is the South Pacific helium-3 plume dynamically active? Earth Planet. Sci. Lett., 61, 63–67.

  • Thompson, A. F., 2008: The atmospheric ocean: eddies and jets in the Antarctic Circumpolar Current. Philos. Trans. Roy. Soc. London, A366, 4529–4541.

    • Search Google Scholar
    • Export Citation

  • Thurnherr, A. M., L. C. St. Laurent, K. G. Speer, J. M. Toole, and J. R. Ledwell, 2005: Mixing associated with sills in a canyon not the midocean ridge flank. J. Phys. Oceanogr., 35, 1370–1381.

    • Search Google Scholar
    • Export Citation

  • Veirs, S. R., R. E. McDuff, M. D. Lilley, and J. R. Delaney, 1999: Locating hydrothermal vents by detecting buoyant, advected plumes. J. Geophys. Res., 104, 29 239–29 247.

    • Search Google Scholar
    • Export Citation

  • Wåhlin, A. K., X. Yuan, G. Björk, and C. Nohr, 2010: Inflow of warm Circumpolar Deep Water in the central Amundsen Shelf. J. Phys. Oceanogr., 40, 1427–1434.

    • Search Google Scholar
    • Export Citation

  • Well, R., J. Lupton, and W. Roether, 2001: Crustal helium in deep Pacific waters. J. Geophys. Res., 106, 14 165–14 177.

  • Well, R., W. Roether, and D. P. Stevens, 2003: An additional deep-water mass in Drake Passage as revealed by 3He data. Deep-Sea Res. I, 50, 1079–1098.

    • Search Google Scholar
    • Export Citation

  • Whitworth, T., III, W. D. Nowlin Jr., A. H. Orsi, R. A. Locanini, and S. G. Smith, 1994: Weddell sea shelf water in the Bransfield Strait and Weddell Scotia Confluence. Deep-Sea Res. I, 41, 629–641.

    • Search Google Scholar
    • Export Citation

  • Wilson, J. T., 1965: Evidence from ocean islands suggesting movement in the Earth. Philos. Trans. Roy. Soc. London, A258, 145–167.

  • Winckler, G., R. Newton, P. Schlosser, and T. J. Crone, 2010: Mantle helium reveals Southern Ocean hydrothermal venting. Geophys. Res. Lett., 31, L05601, doi:10.1029/2009GL042093.

    • Search Google Scholar
    • Export Citation

  • Zhang, L. L., C. Sun, and D. X. Hu, 2012: Interannual variability of the Antarctic Circumpolar Current strength based on merged altimeter data. Chin. Sci. Bull., 57, 2015–2021.

    • Search Google Scholar
    • Export Citation
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