I would like to thank Dr. J. Fasullo for observational plots related to the decadal modulation of Asian monsoon on ENSO, Dr. A. Timmerman for a stimulating discussion on the chaotic nature of ENSO, Ms. Y. Zhong for the calculation of the GISST, and Dr. S. Vavrus for comments on an earlier version of the paper. Comments from two reviewers have helped to improve the paper substantially. This work is supported by NSF and NOAA.
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