• Ardizzone, J., R. Atlas, R. Hoffman, J. Jusem, S. Leidner, and D. Moroni, 2009: New multiplatform ocean surface wind product available. Eos, Trans. Amer. Geophys. Union, 90 .doi:10.1029/2009EO270003.

    • Search Google Scholar
    • Export Citation
  • Arief, D., and S. Murray, 1996: Low-frequency fluctuations in the Indonesian throughflow through Lombok Strait. J. Geophys. Res., 101 , (C5). 1245512464.

    • Search Google Scholar
    • Export Citation
  • Cane, M., 1984: Modeling sea level during El Niño. J. Phys. Oceanogr., 14 , 18641874.

  • Cravatte, S., J. Picaut, and G. Eldin, 2003: Second and first baroclinic Kelvin modes in the equatorial Pacific at intraseasonal timescales. J. Geophys. Res., 108 , 3266. doi:10.1029/2002JC001511.

    • Search Google Scholar
    • Export Citation
  • Drushka, K., J. Sprintall, S. T. Gille, and W. S. Pranowo, 2008: Observations of the 2004 and 2006 Indian Ocean tsunamis from a pressure gauge array in Indonesia. J. Geophys. Res., 113 , C07038. doi:10.1029/2007JC004662.

    • 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
  • Durland, T., and B. Qiu, 2003: Transmission of subinertial Kelvin waves through a strait. J. Phys. Oceanogr., 33 , 13371350.

  • Eriksen, C., M. Blumenthal, S. Hayes, and P. Ripa, 1983: Wind-generated equatorial Kelvin waves observed across the Pacific Ocean. J. Phys. Oceanogr., 13 , 16221640.

    • Search Google Scholar
    • Export Citation
  • Fu, L., 2007: Intraseasonal variability of the equatorial Indian Ocean observed from sea surface height, wind, and temperature data. J. Phys. Oceanogr., 37 , 188202.

    • Search Google Scholar
    • Export Citation
  • Giese, B. S., and D. E. Harrison, 1990: Aspects of the Kelvin wave response to episodic wind forcing. J. Geophys. Res., 95 , (C5). 72897312.

    • Search Google Scholar
    • Export Citation
  • Gordon, A. L., R. D. Susanto, A. Ffield, B. A. Huber, W. Pranowo, and S. Wirasantosa, 2008: Makassar Strait throughflow, 2004 to 2006. Geophys. Res. Lett., 35 , L24605. doi:10.1029/2008GL036372.

    • Search Google Scholar
    • Export Citation
  • Han, W., 2005: Origins and dynamics of the 90-day and 30–60-day variations in the equatorial Indian Ocean. J. Phys. Oceanogr., 35 , 708728.

    • Search Google Scholar
    • Export Citation
  • Han, W., T. Shinoda, L. Fu, and J. McCreary, 2006: Impact of atmospheric intraseasonal oscillations on the Indian Ocean dipole during the 1990s. J. Phys. Oceanogr., 36 , 670690.

    • Search Google Scholar
    • Export Citation
  • Hautala, S. L., J. Potemra, J. T. Sprintall, J. C. Chong, W. Pandoe, N. Bray, and A. G. Ilahude, 2001: Velocity structure and transport of the Indonesian Throughflow in the major straits restricting flow into the Indian Ocean. J. Geophys. Res., 106 , (C9). 1952719546.

    • Search Google Scholar
    • Export Citation
  • Horii, T., H. Hase, I. Ueki, and Y. Masumoto, 2008: Oceanic precondition and evolution of the 2006 Indian Ocean dipole. Geophys. Res. Lett., 35 , L03607. doi:10.1029/2007GL032464.

    • Search Google Scholar
    • Export Citation
  • Iskandar, I., W. Mardiansyah, Y. Masumoto, and T. Yamagata, 2005: Intraseasonal Kelvin waves along the southern coast of Sumatra and Java. J. Geophys. Res., 110 , C04013. doi:10.1029/2004JC002508.

    • Search Google Scholar
    • Export Citation
  • Iskandar, I., Y. Masumoto, and K. Mizuno, 2009: Subsurface equatorial zonal current in the eastern Indian Ocean. J. Geophys. Res., 114 , C06005. doi:10.1029/2008JC005188.

    • Search Google Scholar
    • Export Citation
  • Johnson, E., and M. McPhaden, 1993: Structure of intraseasonal Kelvin waves in the equatorial Pacific Ocean. J. Phys. Oceanogr., 23 , 608625.

    • Search Google Scholar
    • Export Citation
  • Johnson, H., and C. Garrett, 2006: What fraction of a Kelvin wave incident on a narrow strait is transmitted? J. Phys. Oceanogr., 36 , 945954.

    • Search Google Scholar
    • Export Citation
  • Kessler, W., and M. McPhaden, 1995: Oceanic equatorial waves and the 1991–93 El Niño. J. Climate, 8 , 17571774.

  • Luyten, J., and D. Roemmich, 1982: Equatorial currents at semi-annual period in the Indian Ocean. J. Phys. Oceanogr., 12 , 406413.

  • Madden, R., and P. Julian, 1971: Detection of a 40–50 day oscillation in the zonal wind in the tropical Pacific. J. Atmos. Sci., 28 , 702708.

    • Search Google Scholar
    • Export Citation
  • Masumoto, Y., H. Hase, Y. Kuroda, H. Matsuura, and K. Takeuchi, 2005: Intraseasonal variability in the upper layer currents observed in the eastern equatorial Indian Ocean. Geophys. Res. Lett., 32 , L02607. doi:10.1029/2004GL021896.

    • Search Google Scholar
    • Export Citation
  • McCreary, J., 1983: A model of tropical ocean-atmosphere interaction. Mon. Wea. Rev., 111 , 370387.

  • McCreary, J., 1984: Equatorial beams. J. Mar. Res., 42 , 395430.

  • McPhaden, M., 2002: Mixed layer temperature balance on intraseasonal timescales in the equatorial Pacific Ocean. J. Climate, 15 , 26322647.

    • Search Google Scholar
    • Export Citation
  • McPhaden, M., J. Proehl, and L. Rothstein, 1986: The interaction of equatorial Kelvin waves with realistically sheared zonal currents. J. Phys. Oceanogr., 16 , 14991515.

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

  • Peter, B. N., and K. Mizuno, 2000: Annual cycle of steric height in the Indian Ocean estimated from the thermal field. Deep-Sea Res. I, 47 , 13511368.

    • Search Google Scholar
    • Export Citation
  • Potemra, J., S. Hautala, J. Sprintall, and W. Pandoe, 2002: Interaction between the Indonesian Seas and the Indian Ocean in observations and numerical models. J. Phys. Oceanogr., 32 , 18381854.

    • Search Google Scholar
    • Export Citation
  • Qiu, B., M. Mao, and Y. Kashino, 1999: Intraseasonal variability in the Indo-Pacific Throughflow and the regions surrounding the Indonesian Seas. J. Phys. Oceanogr., 29 , 15991618.

    • Search Google Scholar
    • Export Citation
  • Qu, T., Y. Du, J. J. P. McCreary, G. Meyers, and T. Yamagata, 2008: Buffering effect and its related ocean dynamics in the Indonesian Throughflow region. J. Phys. Oceanogr., 38 , 503516.

    • Search Google Scholar
    • Export Citation
  • Rao, S., S. Masson, J. Luo, S. Behera, and T. Yamagata, 2007: Termination of Indian Ocean dipole events in a coupled general circulation model. J. Climate, 20 , 30183035.

    • 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 , 81100.

    • Search Google Scholar
    • Export Citation
  • Romea, R., and J. Allen, 1983: On vertically propagating coastal Kelvin waves at low latitudes. J. Phys. Oceanogr., 13 , 12411254.

  • Saji, N., B. Goswami, P. Vinayachandran, and T. Yamagata, 1999: A dipole mode in the tropical Indian Ocean. Nature, 401 , 360363.

  • Schiller, A., S. E. Wijffels, J. Sprintall, R. Molcard, and P. R. Oke, 2010: Pathways of intraseasonal variability in the Indonesian Throughflow region. Dyn. Atmos. Oceans, 50 , 174200. doi:10.1016/j.dynatmoce.2010.02.003.

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

  • Song, Q., A. Gordon, and M. Visbeck, 2004: Spreading of the Indonesian Throughflow in the Indian Ocean. J. Phys. Oceanogr., 34 , 772792.

    • Search Google Scholar
    • Export Citation
  • Sprintall, J., J. Chong, F. Syamsudin, W. Morawitz, S. Hautala, N. Bray, and S. Wijffels, 1999: Dynamics of the South Java Current in the Indo-Australian Basin. Geophys. Res. Lett., 26 , 24932496.

    • Search Google Scholar
    • Export Citation
  • Sprintall, J., A. Gordon, R. Murtugudde, and R. D. Susanto, 2000: A semiannual Indian Ocean forced Kelvin wave observed in the Indonesian seas in May 1997. J. Geophys. Res., 105 , (C7). 1721717230.

    • 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 .doi:10.1029/2004EO390002.

    • Search Google Scholar
    • Export Citation
  • Sprintall, J., S. E. Wijffels, R. Molcard, and I. Jaya, 2009: Direct estimates of the Indonesian Throughflow entering the Indian Ocean: 2004–2006. J. Geophys. Res., 114 , C07001. doi:10.1029/2008JC005257.

    • Search Google Scholar
    • Export Citation
  • Stammer, D., and C. Wunsch, 1999: Preliminary assessment of the accuracy and precision of TOPEX/POSEIDON altimeter data with respect to the large-scale ocean circulation. J. Geophys. Res., 99 , (C12). 2458424604.

    • Search Google Scholar
    • Export Citation
  • Syamsudin, F., A. Kaneko, and D. B. Haidvogel, 2004: Numerical and observational estimates of Indian Ocean Kelvin wave intrusion into Lombok Strait. Geophys. Res. Lett., 31 , L24307. doi:10.1029/2004GL021227.

    • Search Google Scholar
    • Export Citation
  • van Aken, H. M., I. S. Brodjonegoro, and I. Jaya, 2009: The deep-water motion through the Lifamatola Passage and its contribution to the Indonesian throughflow. Deep-Sea Res. I, 56 , 12031216. doi:10.1016/j.dsr.2009.02.001.

    • Search Google Scholar
    • Export Citation
  • Vinayachandran, P. N., J. Kurian, and C. P. Neema, 2007: Indian Ocean response to anomalous conditions in 2006. Geophys. Res. Lett., 34 , L15602. doi:10.1029/2007GL030194.

    • Search Google Scholar
    • Export Citation
  • Waliser, D. E., R. Murtugudde, and L. E. Lucas, 2003: Indo-Pacific Ocean response to atmospheric intraseasonal variability: 1. Austral summer and the Madden-Julian Oscillation. J. Geophys. Res., 108 , 3160. doi:10.1029/2002JC001620.

    • 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
  • Wyrtki, K., 1973: An equatorial jet in the Indian Ocean. Science, 181 , 262264.

  • Yu, L., and M. M. Rienecker, 1999: Mechanisms for the Indian Ocean warming during the 1997–98 El Niño. Geophys. Res. Lett., 26 , 735738.

    • Search Google Scholar
    • Export Citation
  • Yu, L., and M. M. Rienecker, 2000: Indian Ocean warming of 1997–1998. J. Geophys. Res., 105 , (C7). 1692316939.

  • Zhang, C., 2005: Madden-Julian oscillation. Rev. Geophys., 43 , 136.

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Vertical Structure of Kelvin Waves in the Indonesian Throughflow Exit Passages

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  • 1 Scripps Institution of Oceanography, La Jolla, California
  • | 2 Bandung Institute of Technology, Bandung, Indonesia
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Abstract

The subsurface structure of intraseasonal Kelvin waves in two Indonesian Throughflow (ITF) exit passages is observed and characterized using velocity and temperature data from the 2004–06 International Nusantara Stratification and Transport (INSTANT) project. Scatterometer winds are used to characterize forcing, and altimetric sea level anomaly (SLA) data are used to trace the pathways of Kelvin waves east from their generation region in the equatorial Indian Ocean to Sumatra, south along the Indonesian coast, and into the ITF region.

During the 3-yr INSTANT period, 40 intraseasonal Kelvin waves forced by winds over the central equatorial Indian Ocean caused strong transport anomalies in the ITF outflow passages. Of these events, 21 are classed as “downwelling” Kelvin waves, forced by westerly winds and linked to depressions in the thermocline and warm temperature anomalies in the ITF outflow passages; 19 were “upwelling” Kelvin waves, generated by easterly wind events and linked to shoaling of the thermocline and cool temperature anomalies in the ITF. Both downwelling and upwelling Kelvin waves have similar vertical structures in the ITF outflow passages, with strong transport anomalies over all depths and a distinctive upward tilt to the phase that indicates downward energy propagation. A linear wind-forced model shows that the first two baroclinic modes account for most of the intraseasonal variance in the ITF outflow passages associated with Kelvin waves and highlights the importance of winds both in the eastern equatorial Indian Ocean and along the coast of Sumatra and Java for exciting Kelvin waves.

Using SLA as a proxy for Kelvin wave energy shows that 37% ± 9% of the incoming Kelvin wave energy from the Indian Ocean bypasses the gap in the coastal waveguide at Lombok Strait and continues eastward. Of the energy that continues eastward downstream of Lombok Strait, the Kelvin waves are split by Sumba Island, with roughly equal energy going north and south to enter the Savu Sea.

Corresponding author address: Kyla Drushka, Scripps Institution of Oceanography, 9500 Gilman Dr., La Jolla, CA 92109-0230. Email: kdrushka@ucsd.edu

Abstract

The subsurface structure of intraseasonal Kelvin waves in two Indonesian Throughflow (ITF) exit passages is observed and characterized using velocity and temperature data from the 2004–06 International Nusantara Stratification and Transport (INSTANT) project. Scatterometer winds are used to characterize forcing, and altimetric sea level anomaly (SLA) data are used to trace the pathways of Kelvin waves east from their generation region in the equatorial Indian Ocean to Sumatra, south along the Indonesian coast, and into the ITF region.

During the 3-yr INSTANT period, 40 intraseasonal Kelvin waves forced by winds over the central equatorial Indian Ocean caused strong transport anomalies in the ITF outflow passages. Of these events, 21 are classed as “downwelling” Kelvin waves, forced by westerly winds and linked to depressions in the thermocline and warm temperature anomalies in the ITF outflow passages; 19 were “upwelling” Kelvin waves, generated by easterly wind events and linked to shoaling of the thermocline and cool temperature anomalies in the ITF. Both downwelling and upwelling Kelvin waves have similar vertical structures in the ITF outflow passages, with strong transport anomalies over all depths and a distinctive upward tilt to the phase that indicates downward energy propagation. A linear wind-forced model shows that the first two baroclinic modes account for most of the intraseasonal variance in the ITF outflow passages associated with Kelvin waves and highlights the importance of winds both in the eastern equatorial Indian Ocean and along the coast of Sumatra and Java for exciting Kelvin waves.

Using SLA as a proxy for Kelvin wave energy shows that 37% ± 9% of the incoming Kelvin wave energy from the Indian Ocean bypasses the gap in the coastal waveguide at Lombok Strait and continues eastward. Of the energy that continues eastward downstream of Lombok Strait, the Kelvin waves are split by Sumba Island, with roughly equal energy going north and south to enter the Savu Sea.

Corresponding author address: Kyla Drushka, Scripps Institution of Oceanography, 9500 Gilman Dr., La Jolla, CA 92109-0230. Email: kdrushka@ucsd.edu

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