Editorial Type:
Article
Article Type:
Research Article

Gliders Measure Western Boundary Current Transport from the South Pacific to the Equator

Russ E. Davis Scripps Institution of Oceanography, La Jolla, California

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William S. Kessler NOAA/Pacific Marine Environmental Laboratory, Seattle, Washington

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Jeffrey T. Sherman Scripps Institution of Oceanography, La Jolla, California

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Print Publication:
01 Nov 2012
DOI:
https://doi.org/10.1175/JPO-D-12-022.1
Page(s):
2001–2013
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Abstract

“Spray” gliders, most launched from small boats near shore, have established a sustainable time series of equatorward transport through the Solomon Sea. The first 3.5 years (mid-2007 through 2010) are analyzed. Coast-to-coast equatorward transport through the Solomon Sea fluctuates around a value of 15 Sv (1 Sv ≡ 106 m3 s−1) with variations approaching ±15 Sv. Transport variability is well correlated with El Niño indices like Niño-3.4, with strong equatorward flow during one El Niño and weak flow during two La Niñas. Mean transport is centered in an undercurrent focused in the western boundary current; variability has a two-layer structure with layers separated near 250 m (near the core of the undercurrent) that fluctuate independently. The largest variations are in midbasin, confined to the upper layer, and are well correlated with ENSO. Analysis of velocity and salinity on isopycnals shows that the western boundary current within the Solomon Sea consists of a deep core coming from the Coral Sea and a shallow core that enters the Solomon Sea in mid basin. Analysis of the structure of transport and its fluctuations is presented.

Pacific Marine Environmental Laboratory Contribution Number 3817.

Corresponding author address: Russ. E. Davis, Scripps Institution of Oceanography, MS 0230, La Jolla, CA 92093. E-mail: rdavis@ucsd.edu

Abstract

“Spray” gliders, most launched from small boats near shore, have established a sustainable time series of equatorward transport through the Solomon Sea. The first 3.5 years (mid-2007 through 2010) are analyzed. Coast-to-coast equatorward transport through the Solomon Sea fluctuates around a value of 15 Sv (1 Sv ≡ 106 m3 s−1) with variations approaching ±15 Sv. Transport variability is well correlated with El Niño indices like Niño-3.4, with strong equatorward flow during one El Niño and weak flow during two La Niñas. Mean transport is centered in an undercurrent focused in the western boundary current; variability has a two-layer structure with layers separated near 250 m (near the core of the undercurrent) that fluctuate independently. The largest variations are in midbasin, confined to the upper layer, and are well correlated with ENSO. Analysis of velocity and salinity on isopycnals shows that the western boundary current within the Solomon Sea consists of a deep core coming from the Coral Sea and a shallow core that enters the Solomon Sea in mid basin. Analysis of the structure of transport and its fluctuations is presented.

Pacific Marine Environmental Laboratory Contribution Number 3817.

Corresponding author address: Russ. E. Davis, Scripps Institution of Oceanography, MS 0230, La Jolla, CA 92093. E-mail: rdavis@ucsd.edu
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  • Butt, J., and E. Lindstrom, 1994: Currents off the east coast of New Ireland, Papua New Guinea, and their relevance to regional undercurrents in the western equatorial Pacific Ocean. J. Geophys. Res., 99, 12 503–12 514.

    • Search Google Scholar
    • Export Citation

  • Cravatte, S., A. Ganachaud, Q.-P. Duong, W. S. Kessler, G. Eldin, and P. Dutrieux, 2011: Observed circulation in the Solomon Sea from SADCP data. Prog. Oceanogr., 88, 116–130.

    • Search Google Scholar
    • Export Citation

  • Fine, R. A., R. Lukas, F. M. Bingham, M. J. Warner, and R. H. Gammon, 1994: The western equatorial Pacific: A water mass crossroads. J. Geophys. Res., 99, 25 063–25 080.

    • Search Google Scholar
    • Export Citation

  • Ganachaud, A., and Coauthors, 2008: Southwest Pacific Ocean Circulation and Climate Experiment (SPICE). Part II. Implementation plan. International CLIVAR Project Office CLIVAR Publication Series Number 133, 36 pp.

  • Gu, D. F., and S. G. F. Philander, 1997: Interdecadal climate variability that depends on exchanges between the tropics and extratropics. Science, 275, 805–807.

    • Search Google Scholar
    • Export Citation

  • Hoerner, S. F., 1985: Lifting characteristics of streamline bodies. Fluid-Dynamic Lift: Practical Information on Aerodynamic and Hydrodynamic Lift, Hoerner Fluid Dynamics, 19-1–19-28.

  • Johnson, G. C., B. M. Sloyan, W. S. Kessler, and K. E. McTaggart, 2002: Direct measurements of upper ocean currents and water properties across the tropical Pacific during the 1990s. Prog. Oceanogr., 52, 31–61.

    • Search Google Scholar
    • Export Citation

  • Kessler, W. S., 1999: Interannual variability in the subsurface high-salinity tongue south of the equator at 165°E. J. Phys. Oceanogr., 29, 2038–2049.

    • Search Google Scholar
    • Export Citation

  • Kleeman, R., J. P. McCreary, and B. A. Klinger, 1999: A mechanism for generating ENSO decadal variability. Geophys. Res. Lett., 26, 1743–1746.

    • Search Google Scholar
    • Export Citation

  • Lee, T., and I. Fukumori, 2003: Interannual-to-decadal variations of the tropical–subtropical exchange in the Pacific Ocean: boundary versus interior pycnocline transports. J. Climate, 16, 4022–4042.

    • Search Google Scholar
    • Export Citation

  • Lindstrom, E., R. Lukas, R. Fine, E. Firing, S. Godfrey, G. Meyers, and M. Tsuchiya, 1987: The western equatorial Pacific Ocean circulation study. Nature, 330, 533–537.

    • Search Google Scholar
    • Export Citation

  • Lindstrom, E., J. Butt, R. Lukas, and S. Godfrey, 1990: The flow through Vitiaz Strait and St. George’s Channel, Papua New Guinea. The Physical Oceanography of Sea Straits, L. Pratt, Ed., Kluwer Academic Publishers, 171–189.

  • McPhaden, M. J., and D. X. Zhang, 2002: Slowdown of the meridional overturning circulation in the upper Pacific Ocean. Nature, 415, 603–608.

    • Search Google Scholar
    • Export Citation

  • Melet, A., L. Gourdeau, and J. Verron, 2010: Variability in the Solomon Sea circulation derived from altimeter sea level data. Ocean Dyn., 60, 883–900.

    • Search Google Scholar
    • Export Citation

  • Murray, S., E. Lindstrom, J. Kindle, and E. Weeks, 1995: Transport through the Vitiaz Strait. WOCE Notes, No. 7, WOCE International Project Office, Southampton, United Kingdom, 21–23.

  • Ridgway, K. R., J. S. Godfrey, G. Meyers, and R. Bailey, 1993: Sea level response to the 1986-1987 El Niño Southern Oscillation event in the Western Pacific in the vicinity of Papua New Guinea. J. Geophys. Res., 98 (C9), 16 387– 16395.

    • Search Google Scholar
    • Export Citation

  • Ridgway, K. R., J. R. Dunn, and J. L. Wilkin, 2002: Ocean interpolation by four-dimensional least squares—Application to the waters around Australia. J. Atmos. Oceanic Technol., 19, 1357–1375.

    • Search Google Scholar
    • Export Citation

  • Roemmich, D., and J. Gilson, 2009: The 2004–2008 mean and annual cycle of temperature, salinity, and steric height in the global ocean from the Argo Program. Prog. Oceanogr., 82, 81–100, doi:10.1016/j.pocean.2009.03.004.

    • Search Google Scholar
    • Export Citation

  • Sherman, J., R. E. Davis, W. B. Owens, and J. Valdes, 2001: The autonomous underwater glider “Spray.” IEEE J. Oceanic Eng., 26, 437–446.

    • Search Google Scholar
    • Export Citation

  • Tsuchiya, M., 1968: Upper Ocean Waters of the Intertropical Pacific Ocean. Johns Hopkins, 50 pp.

  • Tsuchiya, M., R. Lukas, R. A. Fine, E. Firing, E. Lindstrom, 1989: Source waters of the Pacific Equatorial Undercurrent. Progr. Oceanogr., 23, 101–147.

    • Search Google Scholar
    • Export Citation
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