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J. Legarreta, A. Sánchez-Lavega (UPV-EHU, Spain)
We have used the properties derived from high-resolution images obtained in the visual range by the Voyager 1 and 2 (in 1979) and Galileo (from 1996-2000) spacecrafts, to study the nature of synoptic-scale Jovian vortices (size above 1500 km, lifetime greater than few months). The measured size, the magnitude and sign of the vorticity, the location in latitude, the zonal velocity and ambient meridional wind shear, have been used as inputs for non-linear numerical simulations of cyclones and anticyclones using the Explicit Planetary Isentropic Coordinate (EPIC) model. Matching the observations (cloud morphology and wind pattern) to the simulations (potential vorticity field), we search for the basic properties of the atmosphere below Jupiter’s ammonia cloud, in particular the mean vertical thermal structure and vertical wind shear above about the 6 bar pressure level. In order to reproduce the anticyclones lifetimes and stability from –60 to +60 deg in latitude, our results show how these properties vary meridionally. In addition we have been able to reproduce the wind pattern and lifetimes of the so-called “barges”, a characteristic type of closed cyclones at near Equatorial latitudes.
Acknowledgements: This work was supported by the Spanish MCYT AYA 2003-03216 and European FEDER.
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Bulletin of the American Astronomical Society, 36 #4
© 2004. The American Astronomical Soceity.