We thank the NOAA/CDC for making the NCEP–NCAR reanalysis data available. The ARSC supplied some computer resources. We thank M. Timlin for evaluating the temporal distribution of the most extreme events. We also thank Drs. S. Akasofu and R. Gerdes for their valuable comments. Finally, we are grateful to the editor, M. P. Hoerling, and two anonymous reviewers, whose careful and constructive reviews improved both presentation and content of this paper. Authors X. Zhang, U. S. Bhatt, and M. Ikeda were supported by the Japanese Marine Science and Technology Center through the International Arctic Research Center, University of Alaska, Fairbanks. J. E. Walsh was funded by the National Science Foundation through Grant OPP-0002239. J. Zhang was supported by funding from the University Partnership for Operational Support.
Ghil, M., and Coauthors, 2002: Advanced spectral methods for climatic time series. Rev. Geophys.,40, 1003, doi:10.1029/ 2000RG000092.
Graham, N. E., , and H. F. Diaz, 2001: Evidence for intensification of North Pacific winter cyclones since 1948. Bull. Amer. Meteor. Soc, 82 , 1869–1893.
Houghton, J. T., , Y. Ding, , D. G. Griggs, , M. Noguer, , P. J. van der Linden, , X. Dai, , K. Maskell, , and C. A. Johnson, Eds.,. 2001: Climate Change 2001: The Scientific Basis. Cambridge University Press, 881 pp.
Kistler, R., and Coauthors, 2001: The NCEP–NCAR 50-Year Reanalysis: Monthly means CD-ROM and documentation. Bull. Amer. Meteor. Soc, 82 , 247–268.
Lin, H., , and J. Derome, 1998: A three-year lagged correlation between the North Atlantic Oscillation and winter condition over the North Pacific and North America. Geophys. Res. Lett, 25 , 2829–2832.
Mann, M. E., , and J. M. Lees, 1996: Robust estimation of background noise and signal detection in climatic time series. Climatic Change, 33 , 409–445.
McCabe, G. J., , M. P. Clark, , and M. Serreze, 2001: Trends in Northern Hemisphere surface cyclone frequency and intensity. J. Climate, 14 , 2763–2768.
Petterssen, S., 1950: Some aspects of the general circulation of the atmosphere. Centenary Proc. of the Royal Meteorological Society, London, United Kingdom, 120–153.
Polyakov, I., and Coauthors, 2002: Observationally based assessment of polar amplification of global warming. Geophys. Res. Lett.,29, 1878, doi:10.1029/2001GL011111.
Proshutinsky, A. Y., , and M. A. Johnson, 1997: Two circulation regimes of the wind-driven Arctic Ocean. J. Geophys. Res, 102 , 12493–12514.
Rogers, J. C., 1990: Patterns of low-frequency monthly sea level pressure variability (1899–1986) and associated wave cyclone frequencies. J. Climate, 3 , 1364–1379.
Serreze, M. C., , J. E. Box, , R. G. Barry, , and J. E. Walsh, 1993: Characteristics of Arctic synoptic activity, 1952–1989. Meteor. Atmos. Phys, 51 , 147–164.
Serreze, M. C., , F. Carse, , and R. Barry, 1997: Icelandic low cyclone activity: Climatological features, linkages with the NAO, and relationships with recent changes in the Northern Hemisphere circulation. J. Climate, 10 , 453–464.
Serreze, M. C., , A. H. Lynch, , and M. P. Clark, 2001: The Arctic frontal zone as seen in the NCEP–NCAR reanalysis. J. Climate, 14 , 1550–1567.
Thompson, D. W., , and J. M. Wallace, 1998: The Arctic Oscillation signature in the winter time geopotential height and temperature fields. Geophys. Res. Lett, 25 , 1297–1300.
Walsh, J. E., , W. L. Chapman, , and T. L. Shy, 1996: Recent decrease of sea level pressure in the central Arctic. J. Climate, 9 , 480–486.
Whittaker, L. M., , and L. H. Horn, 1982: Atlas of Northern Hemisphere extratropical cyclone activity, 1958–1977. University of Wisconsin—Madison, 65 pp.
Zhang, X., , M. Ikeda, , and J. E. Walsh, 2003: Arctic sea ice and freshwater changes driven by the atmospheric leading mode in a coupled sea ice–ocean model. J. Climate, 16 , 2159–2177.