Jupiter’s South Temperate domain: Evolution 1991-1999 and dynamics of cyclonic structured sectors as seen in Hubble maps

–John H. Rogers (2016 March)

Summary

We have recently published detailed reports on the long-term behaviour of the South Temperate domain from 2000 onwards, based on amateur images.  Here we supplement these reports by study of Hubble and other professional images, from 1991-1999 and in recent years, to gain more insight into the cyclonic features which have not been fully resolved from the ground. 

I.  In 1993, after several years when the South Temperate Belt (STB) was absent, its dramatic revival was largely due to the appearance of a new long dark turbulent sector, whose appearance fulfilled the usual requirement for several structured sectors spaced around the domain. In this year, exceptionally, darkening and turbulence spread all around the domain.  The form of the new sector was consistent with the structure of dark STB segments established more recently.

II.  In 1994, Hubble maps showed that the revived dark STB consisted of a series of contiguous cyclonic disturbances, collectively much longer than a typical structured segment.  The following element of the series was the new structured sector of 1992-93, and it had a near-constant rapid drift such that the whole dark STB contracted steadily over the next 5 years, converging on the slower-moving group of great anticyclonic white ovals.  By 1998, there was just one sector of cyclonic disturbance left, and the leading pair of great ovals merged, and new cyclonic features developed tens of degrees preceding the merged oval to generate the next structured sector.  So this whole process appeared to be driven by the new dark sector of 1992-93, which behaved just like structured sectors post-1998.

       Zonal wind profiles from these years confirm the same pattern that we have found in later years, that the jet peaks at 29.5ºS and 32.5ºS are strong alongside dark and turbulent STB segments, and weak or absent in quiescent sectors.

III.  In more recent years, Hubble images of the pale cyclonic sectors (‘STB Remnant’, ‘Ghost’, and ‘Spectre’) confirm that they have cyclonic circulation, and in 2016, also confirm anticyclonic circulation south of the newest one.

THE FULL REPORT IS HERE (PDF), including small versions of the figures:

STB-report_HST_1993-1999-etc_&minifigs.pdf

(Contact JHR if full-size versions of figures are needed.)