This work was supported by NSF Grant ATM-0004479. We are much indebted to Dr. Jeff Whitaker, NOAA/CDC, who provided the model used in this study, and to NCAR for providing the NCEP reanalysis data. We would like to acknowledge the support for this research provided by the Geophysical Fluid Dynamics Institute of the Florida State University (a contribution number will be assigned after publication). We are grateful for discussions of this work with Profs. Robert Hart and Phil Cunningham of FSU. The third author would like to express his gratitude to Dr. C. A. Clayson, director of the Institute, for her support. Finally, we thank two anonymous reviewers, whose comments added much to the manuscript.
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