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SUMMARY:The Range of Planetary Circulations Described by the Dry Primitive
  Equations - Vallis\, G (University of Exeter)
DTSTART:20131206T090000Z
DTEND:20131206T094500Z
UID:TALK49231@talks.cam.ac.uk
CONTACT:Mustapha Amrani
DESCRIPTION:Co-authors: Jonathan Mitchell (UCLA)\, Sam Potter (Princeton U
 niversity) \n\nThe dry primitive equations can\, with appropriate forcing 
 and dissipation\, provide a reasonable simulation of the large-scale featu
 res of the Earth's atmosphere and ocean. In this talk I will describe the 
 behaviour of these PDEs when they are taken out of the terrestrial paramet
 er regime. In n particular\, I will describe their behaviour when the ther
 mal Rossby number\, Ekman number and a radiative relaxation timescale are 
 varied considerably\, moving into a parameter regime more appropriate for 
 Mars or Titan. \n\nI will pay particular attention to the formation of zon
 al jets\, and in particular of equatorial superrotation\, which is a featu
 re of some other planets. It is well-known that zonal jets robustly arise 
 in rotating atmospheres if there is a wavemaker at a particular latitude. 
 Rossby waves are then generated that propagate away\, and eastward momentu
 m converges on the source region producing a zonal jet. The Earth's jet st
 ream is\, in part\, formed this way. However\, on slowly rotating atmosphe
 res it seems unlikely that superrotation is produced by that mechanism. Ra
 ther\, simulations indicate that\, at small thermal Rossby number\, a mech
 anism involving equatorial Kelvin waves is involved. \n
LOCATION:Seminar Room 1\, Newton Institute
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