Stratospheric Memory and Skill of Extended-Range Weather Forecasts

We use an empirical statistical model to demonstrate significant skill in making extended-range forecasts of the monthly-mean Arctic Oscillation (AO). Forecast skill derives from persistent circulation anomalies in the lowermost stratosphere and is greatest during boreal winter. A comparison to the Southern Hemisphere provides evidence that both the time scale and predictability of the AO depend on the presence of persistent circulation anomalies just above the tropopause. These circulation anomalies most likely affect the troposphere through changes to waves in the upper troposphere, which induce surface pressure changes that correspond to the AO.

[1]  M. Hoerling,et al.  The Perfect Ocean for Drought , 2003, Science.

[2]  Varavut Limpasuvan,et al.  Wave-Maintained Annular Modes of Climate Variability* , 2000 .

[3]  John M. Wallace,et al.  North atlantic oscillatiodannular mode: Two paradigms—one phenomenon , 2000 .

[4]  P. R. Julian,et al.  Detection of a 40–50 Day Oscillation in the Zonal Wind in the Tropical Pacific , 1971 .

[5]  T. Shepherd,et al.  The importance of surface pressure changes in the response of the atmosphere to zonally‐symmetric thermal and mechanical forcing , 1989 .

[6]  J. Perlwitz,et al.  Troposphere‐stratosphere dynamic coupling under strong and weak polar vortex conditions , 2001 .

[7]  John M. Wallace,et al.  Stratospheric Connection to Northern Hemisphere Wintertime Weather: Implications for Prediction , 2002 .

[8]  J. Hurrell.  Decadal Trends in the North Atlantic Oscillation: Regional Temperatures and Precipitation , 1995, Science.

[9]  M. Baldwin.  Downward Propagation of the Arctic Oscillation from the Stratosphere to the Troposphere , 1999 .

[10]  W. Norton.  Sensitivity of northern hemisphere surface climate to simulation of the stratospheric polar vortex , 2003 .

[11]  Mark P. Baldwin,et al.  Stratospheric Harbingers of Anomalous Weather Regimes , 2001, Science.

[12]  H. Storch,et al.  Statistical Analysis in Climate Research , 2000 .

[13]  Theodore G. Shepherd,et al.  Issues in Stratosphere-troposphere Coupling , 2002 .

[14]  Keith P. Shine,et al.  On the “Downward Control” of Extratropical Diabatic Circulations by Eddy-Induced Mean Zonal Forces , 1991 .

[15]  J. Wallace,et al.  Annular Modes in the Extratropical Circulation. Part I: Month-to-Month Variability* , 2000 .

[16]  R. X. Black.  Stratospheric Forcing of Surface Climate in the Arctic Oscillation , 2002 .

[17]  J. Wallace,et al.  The Arctic oscillation signature in the wintertime geopotential height and temperature fields , 1998 .

[18]  D. Hartmann,et al.  Eddy–Zonal Flow Feedback in the Northern Hemisphere Winter , 2003 .

[19]  Ping Chen,et al.  Propagation of Planetary Waves between the Troposphere and Stratosphere , 1992 .

[20]  J. Wallace,et al.  Regional Climate Impacts of the Northern Hemisphere Annular Mode , 2001, Science.

[21]  Arun Kumar,et al.  NCEP dynamical seasonal forecast system 2000 , 2002 .