• An, S-I., and B. Wang, 2000: Interdecadal change of the structure of the ENSO mode and its impact on the ENSO frequency. J. Climate, 13 , 20442055.

    • Search Google Scholar
    • Export Citation
  • Annamalai, H., and R. Murtugudde, 2004: Role of the Indian Ocean in regional climate variability. Earth Climate: The Ocean–Atmosphere Interaction, Geophys. Monogr., Vol. 147, Amer. Geophys. Union, 213–246.

  • Annamalai, H., R. Murtugudde, J. Potemra, S-P. Xie, P. Liu, and B. Wang, 2003: Coupled dynamics over the Indian Ocean: Spring initiation of the zonal mode. Deep-Sea Res. II, 50 , 23052330.

    • Search Google Scholar
    • Export Citation
  • Carton, J. A., G. Chepurin, X. Cao, and B. S. Giese, 2000a: A simple ocean data assimilation analysis of the global upper ocean 1950–95. Part I: Methodology. J. Phys. Oceanogr., 30 , 294309.

    • Search Google Scholar
    • Export Citation
  • Carton, J. A., G. Chepurin, and X. Cao, 2000b: A simple ocean data assimilation analysis of the global upper ocean 1950–95. Part II: Results. J. Phys. Oceanogr., 30 , 311326.

    • Search Google Scholar
    • Export Citation
  • Clarke, A. J., 1991: On the reflection and transmission of low-frequency energy at the irregular western Pacific Ocean boundary. J. Geophys. Res., 96 , 32893305.

    • Search Google Scholar
    • Export Citation
  • Delworth, T. L., and Coauthors, 2006: GFDL’s CM2 global coupled climate models. Part I: Formulation and simulation characteristics. J. Climate, 19 , 643674.

    • Search Google Scholar
    • Export Citation
  • du Penhoat, Y., and M. A. Cane, 1991: Effect of low-latitude western boundary gaps on the reflection of equatorial motions. J. Geophys. Res., 96 , 33073322.

    • Search Google Scholar
    • Export Citation
  • England, M. H., and F. Huang, 2005: On the interannual variability of the Indonesian Throughflow and its linkage with ENSO. J. Climate, 18 , 14351444.

    • Search Google Scholar
    • Export Citation
  • Fedorov, A. V., and S. G. Philander, 2000: Is El Nino changing? Science, 288 , 19972002.

  • Ffield, A., and A. L. Gordon, 1992: Vertical mixing in the Indonesian thermocline. J. Phys. Oceanogr., 22 , 184195.

  • Gent, P., and J. McWilliams, 1990: Isopycnal mixing in ocean circulation models. J. Phys. Oceanogr., 20 , 150155.

  • GFDL Global Atmospheric Model Development Team, 2004: The new GFDL global atmosphere and land model AM2–LM2: Evaluation with prescribed SST simulations. J. Climate, 17 , 46414673.

    • Search Google Scholar
    • Export Citation
  • Gnanadesikan, A., and Coauthors, 2006: GFDL’s CM2 global coupled climate models. Part II: The baseline ocean simulation. J. Climate, 19 , 675697.

    • 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 , 1221712238.

    • Search Google Scholar
    • Export Citation
  • Gordon, A. L., 1986: Interocean exchange of thermocline water. J. Geophys. Res., 91 , 50375047.

  • Gordon, A. L., 2001: Interocean exchange. Ocean Circulation and Climate, G. Siedler, J. Church, and J. Gould, Eds., Academic Press, 303–314.

    • Search Google Scholar
    • Export Citation
  • Gordon, A. L., 2005: Oceanography of the Indonesian Seas and their throughflow. Oceanography, 18 , 1427.

  • Gordon, A. L., R. D. Susanto, and A. Ffield, 1999: Throughflow within Makassar Straight. Geophys. Res. Lett., 26 , 33253328.

  • Griffies, S., 1998: The Gent–McWilliams skew flux. J. Phys. Oceanogr., 28 , 831841.

  • Gualdi, S., E. Guilyardi, A. Navarra, S. Masina, and P. Delecluse, 2003: The interannual variability in the Indian Ocean as simulated by a CGCM. Climate Dyn., 20 , 567582.

    • Search Google Scholar
    • Export Citation
  • Haney, R. L., 1971: Surface thermal boundary conditions for ocean circulation models. J. Phys. Oceanogr., 1 , 241248.

  • Harrison, D. E., 1987: Monthly mean island surface winds in the central tropical Pacific and El Niño. Mon. Wea. Rev., 115 , 31333145.

    • Search Google Scholar
    • Export Citation
  • Harrison, D. E., and G. A. Vecchi, 1999: On the termination of El Niño. Geophys. Res. Lett., 26 , 15931596.

  • Hirst, A. C., and J. S. Godfrey, 1993: The role of Indonesian Throughflow in a global ocean GCM. J. Phys. Oceanogr., 23 , 10571086.

  • Huang, B., and J. L. Kinter III, 2002: Interannual variability in the tropical Indian Ocean. J. Geophys. Res., 107 .3199, doi:10.1029/2001JC001278.

    • Search Google Scholar
    • Export Citation
  • Hughes, T. M., A. J. Weaver, and J. S. Godfrey, 1992: Thermohaline forcing of the Indian Ocean by the Pacific Ocean. Deep-Sea Res., 39 , 965995.

    • Search Google Scholar
    • Export Citation
  • Jin, F., 1997: An equatorial ocean recharge paradigm for ENSO. Part I: Conceptual model. J. Atmos. Sci., 54 , 811829.

  • Kleeman, R., and S. B. Power, 1995: A simple atmospheric model of surface heat flux for use in ocean modeling studies. J. Phys. Oceanogr., 25 , 92105.

    • Search Google Scholar
    • Export Citation
  • Large, W. G., J. C. McWilliams, and S. C. Doney, 1994: Oceanic vertical mixing: A review and a model with a vertical K-profile boundary layer parameterization. Rev. Geophys., 32 , 363403.

    • Search Google Scholar
    • Export Citation
  • Larkin, N. K., and D. E. Harrison, 2002: ENSO warm (El Niño) and cold (La Niña) event life cycles: Ocean surface anomaly patterns, their symmetries, asymmetries, and implications. J. Climate, 15 , 11181140.

    • Search Google Scholar
    • Export Citation
  • Lau, N-C., and M. J. Nath, 2003: Atmosphere–ocean variations in the Indo-Pacific sector during ENSO episodes. J. Climate, 16 , 320.

  • Lau, N-C., and M. J. Nath, 2004: Coupled GCM simulation of atmosphere–ocean variability associated with zonally asymmetric SST changes in the tropical Indian Ocean. J. Climate, 17 , 245265.

    • Search Google Scholar
    • Export Citation
  • Lau, N-C., A. Leetmaa, M. J. Nath, and H. Wang, 2005: Influences of ENSO-induced Indo-western Pacific SST anomalies on extratropical atmospheric variability during the boreal summer. J. Climate, 18 , 29222942.

    • Search Google Scholar
    • Export Citation
  • Lee, T., I. Fukumori, D. Menemenlis, Z. Xing, and L. Fu, 2002: Effects of the Indonesian Throughflow on the Pacific and Indian Ocean. J. Phys. Oceanogr., 32 , 14041429.

    • Search Google Scholar
    • Export Citation
  • Li, T., B. Wang, C-P. Chang, and Y. Zhang, 2003: A theory for the Indian Ocean dipole–zonal mode. J. Atmos. Sci., 60 , 21192135.

  • Lukas, R., and E. Lindstrom, 1991: The mixed layer of the Western Equatorial Pacific. J. Geophys. Res., 96 , 33433357.

  • Meyers, G., 1996: Variation of Indonesian Throughflow and the El Niño-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., 42 , 11631174.

  • Murtugudde, R., and A. J. Busalacchi, 1999: Interannual variability of the dynamics and thermodynamics of the tropical Indian Ocean. J. Climate, 12 , 23002326.

    • Search Google Scholar
    • Export Citation
  • Murtugudde, R., A. J. Busalacchi, and J. Beauchamp, 1998: Seasonal-to-interannual effects of the Indonesian throughflow on the tropical Indo-Pacific Basin. J. Geophys. Res., 103 , 2142521441.

    • Search Google Scholar
    • Export Citation
  • Murtugudde, R., J. P. McCreary, and A. J. Busalacchi, 2000: Oceanic processes associated with anomalous events in the Indian Ocean with relevance to 1997–1998. J. Geophys. Res., 105 , 32953306.

    • Search Google Scholar
    • Export Citation
  • Qu, T., G. Meyers, and J. S. Godfrey, 1994: Ocean dynamics in the region between Australia and Indonesia and its influence on the variation of sea surface temperature in a global general circulation model. J. Geophys. Res., 99 , 1843318445.

    • Search Google Scholar
    • Export Citation
  • Rodbell, D. T., G. O. Seltzer, D. M. Anderson, M. B. Abbott, D. B. Enfield, and J. H. Newman, 1999: An ∼15,000-year record of El Nino-driven alluviation in southwestern Ecuador. Science, 283 , 516520.

    • Search Google Scholar
    • Export Citation
  • Rosenthal, Y., D. W. Oppo, B. Linsley, Y. S. Djajadihardja, A. Ridlo, and F. Syamsudin, 2005: Reconstructing Holocene climate variability and the Indonesian Throughflow in the western equatorial Pacific. Eos, Trans. Amer. Geophys. Union, 86 .(Fall Meeting Suppl.), Abstract OS13A-05.

    • Search Google Scholar
    • Export Citation
  • Saji, N. H., S-P. Xie, and T. Yamagata, 2006: Tropical Indian Ocean variability in the IPCC twentieth-century simulations. J. Climate, 19 , 43974417.

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

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

  • Seager, R., N. Harnik, Y. Kushnir, W. Robinson, and J. Miller, 2003: Mechanisms of hemispherically symmetric climate variability. J. Climate, 16 , 29602978.

    • Search Google Scholar
    • Export Citation
  • Song, Q., and A. L. Gordon, 2004: Significance of the vertical profile of the Indonesian Throughflow to the Indian Ocean. Geophys. Res. Lett., 32 .L16307, doi:10.1029/2004GL020360.

    • Search Google Scholar
    • Export Citation
  • Song, Q., G. A. Vecchi, and A. J. Rosati, 2007: Indian Ocean variability in the GFDL coupled climate model. J. Climate, in press.

  • Spall, M. A., and J. Pedlosky, 2005: Reflection and transmission of equatorial Rossby waves. J. Phys. Oceanogr., 35 , 363373.

  • Stouffer, R., and Coauthors, 2006: GFDL’s CM2 global coupled climate models. Part IV: Idealized climate response. J. Climate, 19 , 723740.

    • Search Google Scholar
    • Export Citation
  • Vecchi, G. A., 2006: The termination of the 1997–98 El Niño event. Part II: Mechanisms of atmospheric change. J. Climate, 19 , 26472664.

    • Search Google Scholar
    • Export Citation
  • Vecchi, G. A., and D. E. Harrison, 2003: On the termination of the 2002–03 El Niño event. Geophys. Res. Lett., 30 .1964, doi:10.1029/2003GL017564.

    • Search Google Scholar
    • Export Citation
  • Vecchi, G. A., and D. E. Harrison, 2006: The termination of the 1997–98 El Niño event. Part I: Mechanisms of oceanic change. J. Climate, 19 , 26332646.

    • Search Google Scholar
    • Export Citation
  • Vecchi, G. A., A. T. Wittenberg, and A. Rosati, 2006: Reassessing the role of stochastic forcing in the 1997–1998 El Niño. Geophys. Res. Lett., 33 .L01706, doi:10.1029/2005GL024738.

    • 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., 2004: Climate variability over the tropical Indian Ocean sector in the NSIPP seasonal forecast system. J. Climate, 17 , 47834804.

    • 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
  • Webster, P. J., A. M. Moore, J. P. Loschnigg, and R. R. Leben, 1999: Coupled ocean-atmosphere dynamics in the Indian Ocean during 1997–98. Nature, 401 , 356360.

    • Search Google Scholar
    • Export Citation
  • Wittenberg, A. T., 2002: ENSO response to altered climates. Ph.D. thesis, Princeton University, 475 pp.

  • Wittenberg, A. T., 2004: Extended wind stress analyses for ENSO. J. Climate, 17 , 25262540.

  • Wittenberg, A. T., A. Rosati, N-C. Lau, and J. J. Ploshay, 2006: GFDL’s CM2 global coupled climate models. Part III: Tropical Pacific climate and ENSO. J. Climate, 19 , 698722.

    • Search Google Scholar
    • Export Citation
  • Wyrtki, K., 1973: An equatorial jet in the Indian Ocean. Science, 181 , 262264.

  • Yamagata, T., S. K. Behera, J-J. Luo, S. Masson, M. R. Jury, and S. A. Rao, 2004: Coupled ocean–atmosphere variability in the tropical Indian Ocean. Earth Climate: The Ocean–Atmosphere Interaction, Geophys. Monogr., Vol. 147, Amer. Geophys. Union, 189–211.

All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 7 7 7
PDF Downloads 4 4 4

The Role of the Indonesian Throughflow in the Indo–Pacific Climate Variability in the GFDL Coupled Climate Model

View More View Less
  • 1 Program in Atmospheric and Oceanic Sciences, Princeton University, Princeton, New Jersey
  • | 2 UCAR Visiting Scientist, GFDL, Princeton, New Jersey
  • | 3 National Oceanic and Atmospheric Administration/Geophysical Fluid Dynamics Laboratory, Princeton, New Jersey
Restricted access

Abstract

The impacts of the Indonesian Throughflow (ITF) on the tropical Indo–Pacific climate, particularly on the character of interannual variability, are explored using a coupled general circulation model (CGCM). A pair of CGCM experiments—a control experiment with an open ITF and a perturbation experiment in which the ITF is artificially closed—is integrated for 200 model years, with the 1990 values of trace gases. The closure of the ITF results in changes to the mean oceanic and atmospheric conditions throughout the tropical Indo–Pacific domain as follows: surface temperatures in the eastern tropical Pacific (Indian) Ocean warm (cool), the near-equatorial Pacific (Indian) thermocline flattens (shoals), Indo–Pacific warm-pool precipitation shifts eastward, and there are relaxed trade winds over the tropical Pacific and anomalous surface easterlies over the equatorial Indian Ocean. The character of the oceanic changes is similar to that described by ocean-only model experiments, though the amplitude of many features in the tropical Indo–Pacific is amplified in the CGCM experiments.

In addition to the mean-state changes, the character of tropical Indo–Pacific interannual variability is substantially modified. Interannual variability in the equatorial Pacific and the eastern tropical Indian Ocean is substantially intensified by the closure of the ITF. In addition to becoming more energetic, El Niño–Southern Oscillation (ENSO) exhibits a shorter time scale of variability and becomes more skewed toward its warm phase (stronger and more frequent warm events). The structure of warm ENSO events changes; the anomalies of sea surface temperature (SST), precipitation, and surface westerly winds are shifted to the east and the meridional extent of surface westerly anomalies is larger.

In the eastern tropical Indian Ocean, the interannual SST variability off the coast of Java–Sumatra is noticeably amplified by the occurrence of much stronger cooling events. Closing the ITF shoals the eastern tropical Indian Ocean thermocline, which results in stronger cooling events through enhanced atmosphere–thermocline coupled feedbacks. Changes to the interannual variability caused by the ITF closure rectify into mean-state changes in tropical Indo–Pacific conditions. The modified Indo–Pacific interannual variability projects onto the mean-state differences between the ITF open and closed scenarios, rectifying into mean-state differences. These results suggest that CGCMs need to reasonably simulate the ITF in order to successfully represent not just the mean climate, but its variations as well.

Corresponding author address: Dr. Qian Song, NOAA/Geophysical Fluid Dynamics Laboratory, P.O. Box 308, 201 Forrestal Rd., Princeton, NJ 08542. Email: Qian.Song@noaa.gov

Abstract

The impacts of the Indonesian Throughflow (ITF) on the tropical Indo–Pacific climate, particularly on the character of interannual variability, are explored using a coupled general circulation model (CGCM). A pair of CGCM experiments—a control experiment with an open ITF and a perturbation experiment in which the ITF is artificially closed—is integrated for 200 model years, with the 1990 values of trace gases. The closure of the ITF results in changes to the mean oceanic and atmospheric conditions throughout the tropical Indo–Pacific domain as follows: surface temperatures in the eastern tropical Pacific (Indian) Ocean warm (cool), the near-equatorial Pacific (Indian) thermocline flattens (shoals), Indo–Pacific warm-pool precipitation shifts eastward, and there are relaxed trade winds over the tropical Pacific and anomalous surface easterlies over the equatorial Indian Ocean. The character of the oceanic changes is similar to that described by ocean-only model experiments, though the amplitude of many features in the tropical Indo–Pacific is amplified in the CGCM experiments.

In addition to the mean-state changes, the character of tropical Indo–Pacific interannual variability is substantially modified. Interannual variability in the equatorial Pacific and the eastern tropical Indian Ocean is substantially intensified by the closure of the ITF. In addition to becoming more energetic, El Niño–Southern Oscillation (ENSO) exhibits a shorter time scale of variability and becomes more skewed toward its warm phase (stronger and more frequent warm events). The structure of warm ENSO events changes; the anomalies of sea surface temperature (SST), precipitation, and surface westerly winds are shifted to the east and the meridional extent of surface westerly anomalies is larger.

In the eastern tropical Indian Ocean, the interannual SST variability off the coast of Java–Sumatra is noticeably amplified by the occurrence of much stronger cooling events. Closing the ITF shoals the eastern tropical Indian Ocean thermocline, which results in stronger cooling events through enhanced atmosphere–thermocline coupled feedbacks. Changes to the interannual variability caused by the ITF closure rectify into mean-state changes in tropical Indo–Pacific conditions. The modified Indo–Pacific interannual variability projects onto the mean-state differences between the ITF open and closed scenarios, rectifying into mean-state differences. These results suggest that CGCMs need to reasonably simulate the ITF in order to successfully represent not just the mean climate, but its variations as well.

Corresponding author address: Dr. Qian Song, NOAA/Geophysical Fluid Dynamics Laboratory, P.O. Box 308, 201 Forrestal Rd., Princeton, NJ 08542. Email: Qian.Song@noaa.gov

Save