Jupiter’s southern high-latitude domains: long-lived features and
dynamics, 2001-2012
John Rogers , Gianluigi Adamoli, Grischa Hahn, Michel Jacquesson, Marco Vedovato, & Hans-Jörg Mettig
(JUPOS team and British Astronomical Association)
Summary
Here we present an overview of the three domains in high southern
latitudes of Jupiter, from 36 to 61ºS. Domains are defined as latitude
bands bounded by prograde jets, and we propose a simplified nomenclature for the high-latitude domains and jets. We survey the dynamical
characteristics of the S2, S3, and S4 domains, and of the S2, S3, and S4 prograde jets on their north edges. We also summarise the long-term
history of the major features, especially the long-lived anti-cyclonic ovals.
This report covers the years 2001-2012, from the JUPOS database, with more limited summaries of some aspects back to 1986. We analyse the
drift rates and latitudes both for long-lived ovals and for many smaller, short-lived features. These establish speed-vs-latitude
relations for these spots (Zonal Drift Profiles, ZDP) over most of the latitude range considered. At these high latitudes the ZDPs are close to
the Zonal Wind Profile (ZWP) derived from spacecraft imagery.
The most conspicuous and long-lived features of these domains are anticyclonic white ovals (AWOs). In the S2 domain (S.S. Temperate
domain; 40.5ºS), from 1986 to 2012, there were always 6-9 long-lived AWOs, among which three disappeared (probably all by mergers), five
appeared, and three or four have survived the full 27 years. There seems to be no intrinsic limit to their lifetime. One AWO shows oscillations
of speed and latitude with period ~128 d, excited when it passes oval BA. Small shorter-lived AWOs are also seen, lasting only 1-2 years.
Sectors of SSTB between AWOs sometimes turn into white cyclonic circulations which can last for several years and progressively
lengthen.
One AWO has probably persisted for at least 15 years in the S3 domain (50ºS), and one for at least 26 years in the S4 domain (60ºS). They
show large variations in speed and latitude (following the ZWP), which often comprise oscillations with periods in the range ~33-50 d.
Chains of slow-moving dark spots are sometimes seen in the S2 and S3 domains, on or just south of the retrograde jet. They may be generated
from persistent cyclonic turbulent sectors, as in the S.Temperate domain. The spotty sector in S3 lasted for 6 years.
Of the prograde jets, the S2 jet (36ºS) always carries several small dark spots, with a great range of speeds on the anticyclonic side of the
peak; the peak speed is close to that observed from spacecraft. The S3 jet (43ºS), not previously detected from Earth, is recorded in every
apparition from 2003 onwards. It has occasional dark spots, like those on the S2 jet, but uniquely, the S3 jet mainly carries white spots, on
the cyclonic side of the jet. The S4 jet (53ºS) and S5 jet (61ºS) are not directly detected, but their presence is confirmed by rapid motions
of spots on their flanks.
The report in full can be downloaded via the
links below:
4) Figures, legends & miniatures
John H. Rogers, Ph.D. Jupiter Section Director,
British Astronomical Association
jhr11@cam.ac.uk
http://www.britastro.org/jupiter/