This work was supported by the Climate Dynamics Program of the National Science Foundation (Grant ATM-9905924), the NOAA Office of Global Programs (Grant NA67RJ0150), and the U.S. Agency for International Development (Grant 608-G-00-94-00007). The reanalysis data were obtained from the NOAA–CIRES Climate Diagnostics Center. We thank Jeff Rogers for providing helpful comments on the original manuscript (as a formal peer reviewer) and for the use of his NAO index. The comments of two other reviewers also helped improve the manuscript.
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