• Bailey, R., A. Gronell, H. Phillips, E. Tanner, and G. Meyers, 1994: Quality control cookbook for XBT data [expendable bathythermograph data]. Version 1.1. Marine Laboratories CSIRO Rep. 221, 84 pp.

  • CERSAT, 2002: CERSAT QUIKSCAT Scatterometer mean wind field products user manual, version: 1.0. Department of Oceanography from Space, IFREMER, Ref. C2-MUT-W-03-IF, 47 pp.

  • Cresswell, G. R., and J. R. Luick, 2001: Current measurements in the Maluku Sea. J. Geophys. Res., 106 , 1395313958.

  • Cresswell, G. R., A. Frische, J. Peterson, and D. Quadfasel, 1993: Circulation in the Timor Sea. J. Geophys. Res., 98 , C8. 1437914389.

    • Search Google Scholar
    • Export Citation
  • da Silva, A. M., C. Young, and S. Levitus, 1994: Algorithms and Procedures. Vol. 1, Atlas of Surface Marine Data 1994, NOAA Atlas NESDIS 6, 83 pp.

    • Search Google Scholar
    • Export Citation
  • Domingues, C. M., M. E. Maltrud, S. E. Wijffels, J. A. Church, and M. Tomczak, 2007: Simulated Lagrangian pathways between the Leeuwin Current System and the upper ocean circulation of the southeast Indian Ocean. Deep-Sea Res. II, 54 , 797817.

    • Search Google Scholar
    • Export Citation
  • Dunn, J. R., and K. R. Ridgway, 2002: Mapping ocean properties in regions of complex topography. Deep-Sea Res. I, 49 , 591604.

  • Ffield, A., and A. L. Gordon, 1996: Tidal mixing signatures in the Indonesian Seas. J. Phys. Oceanogr., 26 , 19241937.

  • Ffield, A., and R. Robertson, 2005: Indonesian Seas: Finestructure variability. Oceanography, 18 , 108111.

  • Fieux, M., C. Andrie, P. Delecluse, A. G. Ilahude, A. Kartavtseff, F. Mantisi, R. Molcard, and J. C. Swallow, 1994: Measurements within the Pacific-Indian Oceans throughflow region. Deep-Sea Res. I, 41 , 10911130.

    • Search Google Scholar
    • Export Citation
  • Godfrey, J. S., 1989: A Sverdrup model of the depth-integrated flow for the World Ocean allowing for island circulations. Geophys. Astrophys. Fluid Dyn., 45 , 1–2. 89112.

    • Search Google Scholar
    • Export Citation
  • Godfrey, J. S., 1996: The effect of the Indonesian throughflow on ocean circulation and heat exchange with the atmosphere: A review. J. Geophys. Res., 101 , 1221712237.

    • Search Google Scholar
    • Export Citation
  • Godfrey, J. S., and J. V. Mansbridge, 2000: Ekman transports, tidal mixing, and the control of temperature structure in Australia’s northwest waters. J. Geophys. Res., 105 , C10. 2402124044.

    • Search Google Scholar
    • Export Citation
  • Gordon, A. L., and R. A. Fine, 1996: Pathways of water between the Pacific and Indian Oceans in the Indonesian Seas. Nature, 379 , 146149.

    • Search Google Scholar
    • Export Citation
  • Gordon, A. L., R. D. Susanto, and A. Ffield, 1999: Throughflow within Makassar Strait. Geophys. Res. Lett., 26 , 33253328.

  • Grist, J. P., and S. A. Josey, 2003: Inverse analysis adjustment of the SOC air–sea flux climatology using ocean heat transport constraints. J. Climate, 16 , 32743295.

    • Search Google Scholar
    • Export Citation
  • Hautala, S., J. Sprintall, J. T. Potemra, J. C. Chong, W. Pandoe, N. Bray, and A. Ilahude, 2001: Velocity structure and transport of the Indonesian Throughflow in the major straits restricting flow into the Indian Ocean. J. Geophys. Res., 106 , 1952719546.

    • Search Google Scholar
    • Export Citation
  • Holland, P. W., and R. E. Welsch, 1977: Robust regression using iteratively reweighted least-squares. Commun. Stat. Theory Methods, A6 , 813827.

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

  • Katsumata, K., and S. Wijffels, 2006: Semidiurnal M2 internal tides in the Indo-Australian Basin. Geophys. Res. Lett., 33 .L17601, doi:10.1029/2006GL026861.

    • Search Google Scholar
    • Export Citation
  • Levitus, S., 1982: Climatological Atlas of the World Ocean. NOAA Prof. Paper 13, 173 pp. and 17 microfiche.

  • Liu, Y., M. Feng, J. Church, and D. Wang, 2005: Effect of salinity on estimating geostrophic transport of the Indonesian Throughflow along the IX1 XBT section. J. Oceanogr., 61 , 795801.

    • Search Google Scholar
    • Export Citation
  • Luick, J. L., and G. R. Cresswell, 2001: Current measurements in the Maluku Sea. J. Geophys. Res., 106 , C7. 1395313958.

  • Meyers, G., 1996: Variation of Indonesian throughflow and the El Nino-Southern Oscillation. J. Geophys. Res., 101 , 1225512263.

  • Meyers, G., R. J. Bailey, and A. P. Worby, 1995: Geostrophic transport of Indonesian Throughflow. Deep-Sea Res. I, 42 , 11631174.

  • Molcard, R., M. Fieux, and A. Ilahude, 1996: The Indo-Pacific throughflow in the Timor Passage. J. Geophys. Res., 101 , 1241112420.

  • Molcard, R., M. Fieux, and F. Syamsudin, 2001: The throughflow within Ombai Strait. Deep-Sea Res. I, 48 , 12371253.

  • Murray, S. P., and D. Arief, 1988: Throughflow into the Indian Ocean through the Lombok Strait, January 1985–January 1986. Nature, 333 , 444447.

    • Search Google Scholar
    • Export Citation
  • Oberhuber, J. M., 1988: An atlas based on the COADS data set: The budgets of heat, buoyancy and turbulent kinetic energy at the surface of the global ocean. Max Planck Institut für Meteorologie Rep. 15, 19 pp.

  • Pegion, P. J., M. A. Bourassa, D. M. Legler, and J. J. O’Brien, 2000: Objectively derived daily “winds” from satellite scatterometer data. Mon. Wea. Rev., 128 , 31503168.

    • Search Google Scholar
    • Export Citation
  • Qu, T., and G. Meyers, 2005: Seasonal characteristics of circulation in the southeastern tropical Indian Ocean. J. Phys. Oceanogr., 35 , 255267.

    • Search Google Scholar
    • Export Citation
  • Quadfasel, D., and G. R. Cresswell, 1992: A note on the seasonal variability of the South Java Current. J. Geophys. Res., 97 , C3. 36853688.

    • Search Google Scholar
    • Export Citation
  • Ridgway, K. R., J. R. Dunn, and J. L. Wilkin, 2002: Ocean interpolation by four-dimensional weighted least squares—Application to the waters around Australasia. J. Atmos. Oceanic Technol., 19 , 13571375.

    • Search Google Scholar
    • Export Citation
  • Schneider, N., 1998: The Indonesian Throughflow and the global climate system. J. Climate, 11 , 676689.

  • Sprintall, J., J. T. Potemra, S. L. Hautala, N. A. Bray, and W. W. Pandoe, 2003: Temperature and salinity variability in the exit passages of the Indonesian Throughflow. Deep-Sea Res. II, 50 , 21832204.

    • Search Google Scholar
    • Export Citation
  • Sprintall, J., and Coauthors, 2004: INSTANT: A New International Array to Measure the Indonesian Throughflow. Eos Trans. Amer. Geophys. Union, 85 .369, doi:10.1029/2004EO390002.

    • Search Google Scholar
    • Export Citation
  • Susanto, R. D., and A. L. Gordon, 2005: Velocity and transport of the Makassar Strait throughflow. J. Geophys. Res., 110 .C01005, doi:10.1029/2004JC002425.

    • Search Google Scholar
    • Export Citation
  • Talley, L. D., and J. Sprintall, 2005: Deep expression of the Indonesian Throughflow: Indonesian Intermediate Water in the South Equatorial Current. J. Geophys. Res., 110 .C10009, doi:10.1029/2004JC002826.

    • Search Google Scholar
    • Export Citation
  • Vranes, K., A. L. Gordon, and A. Ffield, 2002: The heat transport of the Indonesian Throughflow and implications for the Indian Ocean heat budget. Deep-Sea Res. II, 49 , 13911410.

    • Search Google Scholar
    • Export Citation
  • Wajsowicz, R. C., and E. K. Schneider, 2001: The Indonesian throughflow’s effect on global climate determined from the COLA Coupled Climate System. J. Climate, 14 , 30293042.

    • Search Google Scholar
    • Export Citation
  • Wajsowicz, R. C., A. L. Gordon, A. Ffield, and R. D. Susanto, 2003: Estimating transport in Makassar Strait. Deep-Sea Res. II, 50 , 21632181.

    • Search Google Scholar
    • Export Citation
  • Wijffels, S., and G. Meyers, 2004: An intersection of oceanic waveguides: Variability in the Indonesian Throughflow region. J. Phys. Oceanogr., 34 , 12321253.

    • Search Google Scholar
    • Export Citation
  • Wijffels, S., E. Firing, and H. L. Bryden, 1994: Direct observations of the Ekman balance at 10°N in the Pacific Ocean. J. Phys. Oceanogr., 24 , 16661679.

    • Search Google Scholar
    • Export Citation
  • Wijffels, S., J. Sprintall, M. Fieux, and N. Bray, 2002: The JADE and WOCE I10/IR6 Throughflow sections in the southeast Indian Ocean. Part 1: Water mass distribution and variability. Deep-Sea Res. II, 49 , 13411362.

    • Search Google Scholar
    • Export Citation
  • Yu, L., R. A. Weller, and B. Sun, 2004: Improving latent and sensible heat flux estimates for the Atlantic Ocean (1988–99) by a synthesis approach. J. Climate, 17 , 373393.

    • Search Google Scholar
    • Export Citation
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A 20-Yr Average of the Indonesian Throughflow: Regional Currents and the Interbasin Exchange

Susan E. WijffelsThe Centre for Australian Weather and Climate Research, Melbourne, Victoria, Australia

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Gary MeyersIntegrated Marine Observing System, University of Tasmania, Hobart, Tasmania, Australia

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J. Stuart GodfreyThe Centre for Australian Weather and Climate Research, Melbourne, Victoria, Australia

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Abstract

Twenty years of monthly or more frequent repeat expendable bathythermograph data are used to estimate the mean geostrophic velocity and transport relative to 750 m of the Indonesian Throughflow (ITF) and its partitioning through the major outflow straits into the Indian Ocean. Ekman transports are estimated from satellite and atmospheric reanalysis wind climatologies. A subsurface maximum near 100 m characterizes the geostrophic ITF, but Ekman flows drive a warm near-surface component as well. A subsurface intensified fresh Makassar Jet feeds the Lombok Strait Throughflow (∼2 Sv; 1Sv ≡ 106 m3 s−1) and an eastward flow along the Nusa Tenggara island chain [the Nusa Tenggara Current (6 Sv)]. This flow feeds a relatively cold 3.0-Sv flow through the Ombai Strait and Savu Sea. About 4–5 Sv pass through Timor Passage, fed by both the Nusa Tenggara Current and likely warmer and saltier flow from the eastern Banda Sea. The Ombai and Timor Throughflow feature distinctly different shear profiles; Ombai has deep-reaching shear with a subsurface velocity maximum near 150 m and so is cold (∼15.5°–17.1°C), while Timor Passage has a surface intensified flow and is warm (∼21.6°–23°C). At the western end of Timor Passage the nascent South Equatorial Current is augmented by recirculation from a strong eastward shallow flow south of the passage. South of the western tip of Java are two mean eastward flows—the very shallow, warm, and fresh South Java Current and a cold salty South Java Undercurrent. These, along with the inflow of the Eastern Gyral Current, recirculate to augment the South Equatorial Current, and greatly increase its salinity compared to that at the outflow passages. The best estimate of the 20-yr-average geostrophic plus Ekman transport is 8.9 ± 1.7 Sv with a transport-weighted temperature of 21.2°C and transport-weighted salinity of 34.73 near 110°E. The warm temperatures of the flow can be reconciled with the much cooler estimates based on mooring data in Makassar Strait by accounting for an unmeasured barotropic and deep component, and local surface heat fluxes that warm the ITF by 2°–4°C during its passage through the region.

Corresponding author address: Susan Wijffels, CSIRO Marine and Atmospheric Research, GPO 1538, Hobart, TAS 7000, Australia. Email: susan.wijffels@csiro.au

Abstract

Twenty years of monthly or more frequent repeat expendable bathythermograph data are used to estimate the mean geostrophic velocity and transport relative to 750 m of the Indonesian Throughflow (ITF) and its partitioning through the major outflow straits into the Indian Ocean. Ekman transports are estimated from satellite and atmospheric reanalysis wind climatologies. A subsurface maximum near 100 m characterizes the geostrophic ITF, but Ekman flows drive a warm near-surface component as well. A subsurface intensified fresh Makassar Jet feeds the Lombok Strait Throughflow (∼2 Sv; 1Sv ≡ 106 m3 s−1) and an eastward flow along the Nusa Tenggara island chain [the Nusa Tenggara Current (6 Sv)]. This flow feeds a relatively cold 3.0-Sv flow through the Ombai Strait and Savu Sea. About 4–5 Sv pass through Timor Passage, fed by both the Nusa Tenggara Current and likely warmer and saltier flow from the eastern Banda Sea. The Ombai and Timor Throughflow feature distinctly different shear profiles; Ombai has deep-reaching shear with a subsurface velocity maximum near 150 m and so is cold (∼15.5°–17.1°C), while Timor Passage has a surface intensified flow and is warm (∼21.6°–23°C). At the western end of Timor Passage the nascent South Equatorial Current is augmented by recirculation from a strong eastward shallow flow south of the passage. South of the western tip of Java are two mean eastward flows—the very shallow, warm, and fresh South Java Current and a cold salty South Java Undercurrent. These, along with the inflow of the Eastern Gyral Current, recirculate to augment the South Equatorial Current, and greatly increase its salinity compared to that at the outflow passages. The best estimate of the 20-yr-average geostrophic plus Ekman transport is 8.9 ± 1.7 Sv with a transport-weighted temperature of 21.2°C and transport-weighted salinity of 34.73 near 110°E. The warm temperatures of the flow can be reconciled with the much cooler estimates based on mooring data in Makassar Strait by accounting for an unmeasured barotropic and deep component, and local surface heat fluxes that warm the ITF by 2°–4°C during its passage through the region.

Corresponding author address: Susan Wijffels, CSIRO Marine and Atmospheric Research, GPO 1538, Hobart, TAS 7000, Australia. Email: susan.wijffels@csiro.au

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