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SUMMARY:Modelling the zonal winds of the giant planets - Dr. Thomas Gastin
 e (Max Planck)
DTSTART:20141013T150000Z
DTEND:20141013T160000Z
UID:TALK50962@talks.cam.ac.uk
CONTACT:Dr. Jaroslav Dudik
DESCRIPTION:The surface zonal winds (i.e. flows independent of longitude) 
 observed in the giant planets form a complex jet pattern with alternating 
 eastward and westward directions. While the main equatorial band is progra
 de on Jupiter and Saturn\, both Uranus and Neptune have a pronounced retro
 grade equatorial jet.\n\nThe depth of these zonal winds remains however po
 orly known. Theoretical scenarios range from "shallow models"\, that assum
 e that these zonal flows are  restricted to a very thin layer close to the
  surface\; to "deep models" that suppose that the jets are maintained by d
 eep-seated convective motions that involve the whole molecular envelope. T
 he latter idea is supported by fully 3-D numerical simulations using the B
 oussinesq approximation\, that assumes the reference state (temperature\, 
 density\, ...) to be constant with radius. While this approximation is sui
 table for the liquid iron cores of terrestrial planets\, it becomes rather
  dubious in the envelopes of the four giant planets where density increase
 s by several orders of magnitude. The anelastic approximation thus provide
 s a more realistic framework to\nsimulate the dynamics of the zonal flows 
 in such planets as it allows compressibility effects while filtering out f
 ast acoustic waves.\n\nHere\, I therefore adopt an anelastic formulation t
 o simulate 3-D compressible flows in rapidly rotating spherical shells. I 
 will present the results of a \nparameter study on the effects of backgrou
 nd density stratification and discuss the influences on both convective fl
 ows and zonal jets.
LOCATION:MR14\,  Centre for Mathematical Sciences\, Wilberforce Road\, Cam
 bridge
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