A Comparative Study of Jovian Anticyclone Properties from a Six-Year (1994–2000) Survey

✍ Scribed by Raúl Morales-Juberı́as; Agustin Sánchez-Lavega; J. Lecacheux; F. Colas

• Publisher: Elsevier Science
• Year: 2002
• Tongue: English
• Weight: 884 KB
• Volume: 157
• Category: Article
• ISSN: 0019-1035
• DOI: 10.1006/icar.2001.6819

✦ Synopsis

We have used the Hubble Space Telescope archived images of Jupiter for the period 1994-2000, complemented by ground-based telescopic observations, to study in detail the long-term properties of synoptic-scale anticyclonic vortices (size > 1500 km, lifetime > months). We have also analyzed a set of Voyager 1 and 2 images obtained in 1979 to compare anticyclone properties from the two different periods. The latitudinal range covered by this survey spans 75 • N to 75 • S, encompassing 12 anticyclonic zones. We present data on vortex size, aspect ratio, number, latitude location, lifetime, motion, interaction, and morphology for more than 100 vortices. We study empirically the relation between these properties and the mean ambient zonal flow.

We show that most of these properties are not related to latitude and location relative to the jet pattern. However, a significant linear anticorrelation is found when plotting vortex relative speed (vortex propagation speed minus zonal flow velocity) against the zonal flow velocity at the central latitude of each vortex. As the mean eastward flow increases its velocity within a given anticyclonic domain, vortex velocity becomes more westward. This relation holds for all anticyclones except those moving at high velocities (at latitudes 20 • S and 23 • N), whose origin appears to be of a different nature. Moreover, there is also some evidence that the drift rate could be connected to the planetary minus flow vorticity gradient (most conspicuous at 40 and 45 • N). We present simple dynamical interpretations of these observations.