I would like to thank Prof. Julia M. Slingo for useful comments on an earlier draft of this paper and for insightful discussions along with Drs. Pete Inness and Steve Woolnough (Reading University). Drs. Chidong Zhang (RSMS) and Harry Hendon (BMRC) clarified issues regarding model I and model II. Dr. George Kiladis (NOAA) provided helpful discussions regarding the regression technique. Dr. Krishna AchutaRao (PCMDI) provided assistance in processing the NCEP–NCAR reanalysis. The NCEP–NCAR reanalysis was obtained from the NOAA–CIRES Climate Diagnostics Center, Boulder, Colorado (http://www.cdc.noaa.gov/). I gratefully acknowledge the support of the NCAS Centre for Global Atmospheric Modelling and the Department of Meteorology at the University of Reading, United Kingdom, at which a portion of this work was completed. This work was performed under the auspices of the U.S. Department of Energy by the University of California Lawrence Livermore National Laboratory under Contract W-7405-Eng-48.
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