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AGU: Geophysical Research Letters

 

Keywords

  • stratosphere-troposphere coupling
  • Northern Annular Mode
  • stratospheric sudden warming

Index Terms

  • Atmospheric Processes: Stratosphere/troposphere interactions
  • Mathematical Geophysics: Persistence, memory, correlations, clustering
  • Global Change: Climate variability
  • Global Change: Climate dynamics
  • Mathematical Geophysics: Prediction

Abstract

GEOPHYSICAL RESEARCH LETTERS, VOL. 36, L24801, 5 PP., 2009
doi:10.1029/2009GL040913

Stratospheric influence on the tropospheric circulation revealed by idealized ensemble forecasts

E. P. Gerber

Center for Atmosphere Ocean Science, Courant Institute, New York University, New York, New York, USA

C. Orbe

Department of Applied Physics and Applied Mathematics and Department of Earth and Environmental Science, Columbia University, New York, New York, USA

L. M. Polvani

Department of Applied Physics and Applied Mathematics and Department of Earth and Environmental Science, Columbia University, New York, New York, USA

The coupling between the stratosphere and troposphere following Stratospheric Sudden Warming (SSW) events is investigated in an idealized atmospheric General Circulation Model, with focus on the influence of stratospheric memory on the troposphere. Ensemble forecasts are performed to confirm the role of the stratosphere in the observed equatorward shift of the tropospheric midlatitude jet following an SSW. It is demonstrated that the tropospheric response to the weakening of the lower stratospheric vortex is robust, but weak in amplitude and thus easily masked by tropospheric variability. The amplitude of the response in the troposphere is crucially sensitive to the depth of the SSW. The persistence of the response in the troposphere is attributed to both the increased predictability of the stratosphere following an SSW, and the dynamical coupling between the tropospheric jet and lower stratosphere. These results suggest value in resolving the stratosphere and assimilating upper atmospheric data in forecast models.

Received 14 September 2009; accepted 17 November 2009; published 16 December 2009.

Citation: Gerber, E. P., C. Orbe, and L. M. Polvani (2009), Stratospheric influence on the tropospheric circulation revealed by idealized ensemble forecasts, Geophys. Res. Lett., 36, L24801, doi:10.1029/2009GL040913.

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