The NCEP–NCAR reanalysis data were obtained from the National Center for Atmospheric Research, the GICE and HadISST datasets were obtained from the British Atmospheric Data Center, the AO data are from the NOAA Climate Prediction Center, the PDO data are from N. Mantua, the buoy data are from the International Arctic Buoy Program, and the passive microwave data are from the Polar Remote Sensing Group at the Jet Propulsion Laboratory. We gratefully acknowledge discussions with D. Rothrock, A. Schweiger, and M. Steele, and the very helpful comments of the reviewers. This work was supported by the NASA Cryospheric Sciences, Global Modeling and Analysis, and Radiation Sciences Programs; the NOAA Arctic Research Program; and the NSF Office of Polar Programs.
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