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SUMMARY:Stratosphere-Troposphere Coupling:  The Importance of Stationary P
 lanetary Waves - Edwin Gerber\, Columbia University
DTSTART:20071002T093000Z
DTEND:20071002T103000Z
UID:TALK7892@talks.cam.ac.uk
CONTACT:Ryan Woodard
DESCRIPTION:I will discuss the impact of topographically forced stationary
  waves in the dynamical coupling between the stratosphere and the troposph
 ere in a simple atmospheric General Circulation Model similar to that of P
 olvani and Kushner (2002\, GRL).  I find that the mean structure and varia
 bility of the polar vortex in this model is very sensitive to the structur
 e of the topography\, and Northern Hemisphere-like variability\, with the 
 correct frequency of warming events\, occurs only for a relatively narrow 
 range of topographic heights.  The variable polar vortex (i.e. one associa
 ted with realistically frequent sudden warmings) is less coupled to the tr
 oposphere on climatological timescales than in the absence of topographic 
 forcing. On intraseasonal timescales\, however\, coupling between the stra
 tosphere and troposphere depends critically on the stationary wave induced
  variability of the polar vortex.
LOCATION:British Antarctic Survey\, Room 330B
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