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SUMMARY:The Onset of Instability for Zonal Stratospheric Flows
DTSTART:20260515T120000Z
DTEND:20260515T133000Z
DTSTAMP:20260503T045200Z
UID:indico-event-16469@indico.math.cnrs.fr
CONTACT:cecile@ihes.fr
DESCRIPTION:Speakers: Hao Zhu (Nanjing University)\n\nSéminaire d'Analyse
 \nIn this talk\, we discuss some qualitative aspects of the dynamics of th
 e Euler equation on a rotating sphere that are relevant or stratospheric f
 lows. Zonal flow dominates the dynamics of the stratosphere and for most k
 nown planetary stratospheres the observed flow pattern is a small perturba
 tion of an n-jet. Since the 1-jet and the 2-jet are stable\, the main inte
 rest is the onset of instability for the 3-jet. We prove that the 3-jet is
  linearly unstable if and only if the rotation rate belongs to a critical 
 interval. Turning to the nonlinear problem\, we prove that linear instabil
 ity implies nonlinear instability and that\, as the rotation rate goes to 
 infinity\, nearby traveling waves change gradually from a cat's eyes strea
 mline pattern to a profile with no stagnation points. This talk is based o
 n a joint work with Profs. Adrian Constantin\, Pierre Germain and Zhiwu Li
 n.\n========\nPour être informé des prochains séminaires vous pouvez vo
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 .\n\nhttps://indico.math.cnrs.fr/event/16469/
LOCATION:Amphithéâtre Léon Motchane (IHES)
URL:https://indico.math.cnrs.fr/event/16469/
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