Saturnʹs cloud morphology and zonal winds before the Cassini encounter

Analyses of Hubble Space Telescope (HST) images of Saturn obtained from August 2003 to March 2004, with extensive support from ground-based telescopes, have been used to characterize the cloud morphology and motions in its atmosphere few months before the Cassini encounter. We present data on the major meteorological features as potential targets for Cassini observations. We extend our previous measurements of the zonal winds during the 1996–2002 period (A. Sánchez-Lavega et al., 2003, Nature, 423, 623–625), confirming the strong change in the equatorial jet, and the high hemispheric symmetry of the zonal wind pattern.