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SUMMARY:The atmospheric response to Arctic amplification: Insights from id
 ealised models - Will Seviour (Exeter)
DTSTART:20250203T130000Z
DTEND:20250203T140000Z
UID:TALK226684@talks.cam.ac.uk
CONTACT:Bethan Wynne-Cattanach
DESCRIPTION:Over recent decades the Arctic has warmed about three times as
  much as the global average\, a phenomenon known as Arctic amplification (
 AA). There has been much interest in the extent to which AA can influence 
 mid-latitude climate\, with some studies suggesting that it may drive more
  frequent or long-lived weather extremes. However\, general circulation mo
 dels (GCMs) simulate widely diverging responses to polar heating\, both in
  the mean atmospheric circulation and its variability. In this talk I will
  present two examples of recent work from my group\, in which an idealised
  model\, Isca\, helps to explain some of the causes of this uncertainty. I
 n the first\, I will discuss the response of the persistence of surface te
 mperature anomalies to AA. I will show that this response is large but abs
 ent in most GCM experiments due to the method by which they remove sea-ice
 . The persistence response is largest in the Arctic\, but extends to mid-l
 atitudes\, where it is dynamically-driven\, caused by a slowing of meridio
 nal wind anomalies. In the second example\, I will discuss the ‘stratosp
 heric pathway’\, by which AA may dynamically impact lower latitudes. I w
 ill show that\, by varying a single parameter that controls the mean stren
 gth of the stratospheric polar vortex\, a range of stratospheric responses
  (both a strengthening and a weakening of the polar vortex) can be obtaine
 d\, similar to the range seen in GCMs. These range of stratospheric respon
 ses\, in turn\, significantly impact the magnitude of the shift of the edd
 y-driven jet.
LOCATION:MR3\, CMS
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