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SUMMARY:The stratospheric polar vortex\, El Nino and tropospheric weather 
 and climate - Prof. Hans Graf\, Dept. of Geography
DTSTART:20140219T130000Z
DTEND:20140219T140000Z
UID:TALK50907@talks.cam.ac.uk
CONTACT:Mike Davey
DESCRIPTION:I will talk about some recent work showing how the effect of t
 he stratospheric polar vortex on tropospheric climate is modulated by El N
 ino/La Nina. I will also show that "continental winter warming" that is ob
 served after strong volcanic eruptions is not a common feature of a strong
  polar vortex. The strongest tropospheric anomalies are found for warm ENS
 O and weak polar vortex. Finally I will briefly introduce a significant li
 nk of the Arctic Oscillation (which is linked to the polar vortex) with El
  Nino showing that without a positive AO index in spring there is no El Ni
 no evolution even if the Seasonal Footprint Pattern (which is related to P
 DO) is in favour of El Nino. This will allow me to introduce an "old" pape
 r I have published in 1986 featuring Central Pacific warming as a prerequi
 site for El Nino. 
LOCATION:MR5\, Centre for Mathematical Sciences
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