This article was funded by Cooperative Agreement AN07GP0213 from the National Oceanic and Atmospheric Administration (NOAA), by EU FP 6 Contract GOCE-CT-2003-505539 from the ENSEMBLES project, and by the Swiss National Science Foundation through the National Centre for Competence in Research (NCCR) Climate. The views expressed herein are those of the authors and do not necessarily reflect the views of NOAA or any of its subagencies. The authors thank the NCCR Climate for financing Weigel’s research visit to the IRI, which facilitated this collaboration. Special thanks are due to M. S. J. Harrison for his role in initiating and encouraging this work. Helpful comments from A. G. Barnston, P. Della-Marta, and two anonymous referees are gratefully acknowledged. Computer code for most of the procedures presented in this article, and written in Fortran and R, is available from the authors.
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