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SUMMARY:Planetary wave propagation and breaking between the eddy-driven an
 d subtropical jets - Amanda O'Rourke (Princeton)
DTSTART:20120629T120000Z
DTEND:20120629T130000Z
UID:TALK38850@talks.cam.ac.uk
CONTACT:29017
DESCRIPTION:The annular modes are the dominant mode of low frequency varia
 bility in the extratropical atmosphere and have been associated with an in
 teraction of the midlatitude eddies and the upper tropospheric jets. The i
 nteraction of eddies with the background flow composed of a gradually sepa
 rated stirred and relaxed jet is investigated in an idealized model. A min
 imum bound on eddy phase speed that is dependent on zonal wavenumber\, lat
 itude\, and the background potential vorticity gradient is proposed. Cospe
 ctral analysis of eddy momentum flux convergence shows that the eddy activ
 ity is well confined between the maximum and minimum eddy phase speeds fro
 m linear theory for varying background states. This minimum phase speed re
 presents a turning line for meridionally propagating waves and its presenc
 e can influence the development of a double-jet state. This suggests that 
 wave reflection at turning lines may play an important role in setting up 
 the zonal mean atmospheric circulation. The significance of turning lines 
 in more complex models\, such as a primitive equations model\, will be dis
 cussed.\n
LOCATION:MR14 (NB not the usual MR2)\, Centre for Mathematical Sciences\, 
 Wilberforce Road\, Cambridge
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