The daily mean NCEP–NCAR reanalyses were obtained from the National Oceanic and Atmospheric Administration Climate Diagnostics Center. We are very grateful to Mark Baldwin for making the NAM signature time series available and providing an update. We thank Dr. A. J. Miller of the Climate Prediction Center at NCEP and Dr. Paul A. Newman of the Atmospheric Chemistry and Dynamics Branch (Code 916) at NASA GSFC for producing the stratospheric analyses. We also thank the Goddard DAAC for distributing the data as part of NASA's Mission to Planet Earth program. We thank Ted Shepherd, Paul Kushner, Marvin Geller, David Rind, James Hansen, and an anonymous reviewer for helpful comments on the manuscript. JP's research is supported by the NASA Earth Science Program. NH is supported by National Oceanic and Atmospheric Administration Grant UCSIO-CU-02165401-SCF and a Stork-Doherty Lecturship at the Lamont-Doherty Earth Observatory.
Baldwin, M. P., , and T. J. Dunkerton, 1999: Propagation of the Arctic Oscillation from the stratosphere to the troposphere. J. Geophys. Res, 104 , 30937–30946.
Baldwin, M. P., , D. B. Stephenson, , D. Thompson, , T. J. Dunkerton, , A. J. Charlton, , and A. O'Neill, 2003: Stratospheric memory and skill of extended-range weather forecasts. Science, 301 , 636–640.
Bretherton, C. S., , C. Smith, , and J. M. Wallace, 1992: An intercomparision of methods for finding coupled patterns in climate data. J. Climate, 5 , 541–560.
Christiansen, B., 2001: Downward propagation of zonal mean zonal wind anomalies from the stratosphere to the troposphere: Model and reanalysis. J. Geophys. Res, 106 , 27307–27322.
Czaja, A., , and C. Frankignoul, 2002: Observed impact of Atlantic SST anomalies on the North Atlantic Oscillation. J. Climate, 15 , 606–623.
Geller, M. A., , and J. C. Alpert, 1980: Planetary wave coupling between the troposphere and the middle atmosphere as a possible sun-weather mechanism. J. Atmos. Sci, 37 , 1197–1214.
Harnik, N., , and R. S. Lindzen, 2001: The effect of reflecting surfaces on the vertical structure and variability of stratospheric planetary waves. J. Atmos. Sci, 58 , 2872–2894.
Hartley, D. E., , J. T. Villarin, , R. X. Black, , and C. A. Davis, 1998: A new perspective on the dynamical link between the stratosphere and troposphere. Nature, 391 , 471–474.
Haynes, P. H., , C. J. Marks, , M. E. McIntyre, , T. G. Shepherd, , and K. P. Shine, 1991: On the “downward control” of extratropical diabatic circulation by eddy-induced mean zonal forces. J. Atmos. Sci, 48 , 651–678.
Kodera, K., , and Y. Kuroda, 2000a: A mechanistic model study of slowly propagating coupled stratosphere–troposphere variability. J. Geophys. Res, 105 , 12361–12370.
Kodera, K., , and Y. Kuroda, 2000b: Tropospheric and stratospheric aspects of the Arctic Oscillation. Geophys. Res. Lett, 27 , 3349–3352.
Kodera, K., , Y. Kuroda, , and S. Pawson, 2000: Stratospheric sudden warmings and slowly propagating zonal-mean zonal wind anomalies. J. Geophys. Res, 105 , 12351–12359.
Kuroda, Y., , and K. Kodera, 1999: Role of planetary waves in the stratosphere–troposphere coupled variability in the Northern Hemisphere winter. Geophys. Res. Lett, 26 , 2375–2378.
Limpasuvan, V., , D. W. J. Thompson, , and D. L. Hartmann, 2004: The life cycle of the Northern Hemisphere sudden stratospheric warmings. J. Climate, 17 , 2584–2596.
Matsuno, T., 1970: Vertical propagation of stationary planetary waves in the winter Northern Hemisphere. J. Atmos. Sci, 27 , 871–883.
Perlwitz, J., , and H-F. Graf, 2001a: Troposphere–stratosphere dynamic coupling under strong and weak polar vortex conditions. Geophys. Res. Lett, 28 , 271–274.
Perlwitz, J., , and H-F. Graf, 2001b: The variability of the horizontal circulation in the troposphere and stratosphere—A comparison. Theor. Appl. Climatol, 69 , 149–161.
Perlwitz, J., , and N. Harnik, 2003: Observational evidence of a stratospheric influence on the troposphere by planetary wave reflection. J. Climate, 16 , 3011–3026.
Plumb, R. A., , and K. Semeniuk, 2003: Downward migration of extratropical zonal wind anomalies. J. Geophys. Res.,108, 4223, doi:10.1029/2002JD002773.
Polvani, L. M., , and P. Kushner, 2002: Tropospheric response to stratospheric perturbations in a relatively simple general circulation model. Geophys. Res. Lett.,29, 1114, doi:10.1029/ 2001GL014284.
Polvani, L. M., , and D. W. Waugh, 2004: Upward wave activity flux as a precursor to extreme stratospheric events and subsequent anomalous surface weather regimes. J. Climate, 17 , 3547–3553.
Schmitz, G., , and N. Grieger, 1980: Model calculations on the structure of planetary waves in the upper troposphere and lower stratosphere as a function of the wind field in the upper stratosphere. Tellus, 32 , 207–214.
Song, Y., , and W. A. Robinson, 2004: Dynamical mechanisms for stratospheric influences on the troposphere. J. Atmos. Sci, 61 , 1711–1725.
Thompson, D. W. J., , and J. M. Wallace, 2000: Annular modes in the extratropical circulation. Part I: Month-to-month variability. J. Climate, 13 , 1000–1016.
Thompson, D. W. J., , M. P. Baldwin, , and J. M. Wallace, 2002: Stratospheric connection to Northern Hemisphere wintertime weather: Implications for prediction. J. Climate, 15 , 1421–1428.
Zhou, S., , A. J. Miller, , J. Wand, , and J. K. Angell, 2002: Downward-propagating temperature anomalies in the preconditioned polar stratosphere. J. Climate, 15 , 781–792.