The author would like to thank Dr. Sumant Nigam and an anonymous reviewer for their constructive comments and Dr. Bin Wang for providing his analyzed data. Discussions with Drs. George Philander, Bin Wang, Kikuro Miyakoda, and Ping Chang are greatly appreciated. Thanks also to Dr. Julian Wang for providing the NCEP 4D assimilation dataset. Part of this work was done when the author was a visiting scientist at the Atmospheric and Oceanic Sciences Program of the Princeton University and at the University Corporation for Atmospheric Research. Additional support provided by the Office of Naval Research and Naval Research Laboratory, under Program Element 0601153N, is gratefully acknowledged.
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