The authors thank Brian Hoskins, Klaus Weickmann, Matthew Wheeler, and Tercio Ambrizzi for helpful discussions and comments. The OLR and NCEP–NCAR reanalysis data were provided through the NOAA Climate Diagnostics Center (http://www.cdc.noaa.gov). This research was supported by the Pan-American Climate Studies Program, under project GC95-820, sponsored by NOAA’s Office of Global Programs.
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