The authors thank David Karoly for helpful discussions and comments, and RAM thanks J. Caron and T. Kestin for help with IDL. The comments of two anonymous reviewers helped to improve the manuscript from its original version. The station data were provided by Will Spangler of the Data Support Section at NCAR (http://www.scd.ucar.edu/dss/). The NOAA Climate Diagnostics Center (http://www.cdc.noaa.gov) provided the NCEP–NCAR reanalysis data and, together with Dr. Matthew Wheeler, the OLR data. This research was carried out while one of the authors (RAM) was a visitor at the Cooperative Research Centre for Southern Hemisphere Meteorology. This research was supported in part through the Australian Government Cooperative Research Centres Program.
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