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Profeesor Jin-Yi Yu
Department of Earth System Science
University of California, Irvine



The fundamental physical processes that give rise to El Nino-Southern Oscillation (ENSO) are believed to be within the tropical Pacific. However, climate features external to the tropical Pacific may be capable of affecting ENSO behaviors. In this study, we perform experiments with a coupled atmosphere-ocean GCM (CGCM) to examine the roles of the Indian Ocean-Monsoon system in the decadal modulation of ENSO. In the control simulation, the oceanic component of the CGCM includes only the tropical Pacific Ocean (i.e., the Pacific Run). In the second CGCM simulation, both the Indian and Pacific Oceans are included in the ocean model component (i.e., the Indo-Pacific Run). In the third simulation, only the Indian Ocean is included in the ocean model component (i.e., The indian-Ocean Run). The Indo-Pacific Run has been integrated for 100 years, and the other two runs have been integrated for 50 years.

Our CGCM experiments show that the Indian Ocean-Monsoon system can modulate the amplitude and frequency of ENSO and produce interdecadal ENSO variations. We have examined the major differences between the strong and weak ENSO decades in their atmospheric and oceanic mean states. We also address the thermocline depth, wind stress strength, Indonesian throughflow, and Asian Monsoon variations. Our results indicate that the strong and weak ENSO decades are very different in their thermocline depths and Walker circulation strengths. We also found that ENSO-Monsoon relationship is less "typical" and more irregular when the role of Indian Ocean is considered.

Related Publications

  • Yu, J.-Y., 2005: Understanding El Nino Southern Oscillation and its interactions with the Indian Ocean and monsoon. Book chapter in Recent Progress in Atmospheric Sciences with Applications to the Asia-Pacific Region, submitted
  • Yu, J.-Y. , 2005: Enhancement of ENSO's persistence barrier by biennial variability in a coupled atmosphere-ocean general circulation model. Geophysical Research Letters, 32, L13707, doi:10.1029/2005GL023406.
  • Yu, J.-Y. and K. M. Lau, 2004: Contrasting Indian Ocean SST variability with and without ENSO influence: A coupled atmosphere-ocean GCM study. Meteorology and Atmospheric Physics, DOI: 10.1007/s00703-004-0094-7.
  • Yu, J.-Y., S.-P. Weng, and J. D. Farrara, 2003: Ocean Roles in the TBO Transitions of the Indian-Australian Monsoon System. Journal of Climate, 16, 3072-3080.
  • Yu, J.-Y., C. R. Mechoso, J. C. McWilliams, and A. Arakawa 2002: Impacts of the Indian Ocean on the ENSO cycle. Geophysical Research Letters, 29(8), 1204, doi:10.1029/2001GL014098.
  • Yu, J.-Y., 2000: Climate variability over the Indo-Pacific region and the role of the Indian Ocean. Proceedings of the International Conference of Environmental Modeling and Simulation, 23-26 January, San Diego, California, 17-22.

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