We thank Eli Galanti, Gabriel Vecchi, Mojib Latif, Fei-Fei Jin, Gerrit Burgers, Matt Harrison, Shaoqing Zhang, and Tony Rosati for helpful discussions. Three anonymous reviewers greatly improved the presentation. GG, IE, and ET are supported by NSF Climate Dynamics program, grant ATM-0351123, the Geophysical Fluid Dynamics Laboratory, and the McDonnell Foundation. IE is also partially supported by a NASA Earth System Science Fellowship. ERA-40 data used in this study have been obtained from the ECMWF data server. The calculations of this study were carried out on the Harvard Crimson Grid and the “Swell” Linux cluster at Harvard. Thanks to Chris Walker for computational support.
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