Rogers
JH, Mettig H-J, and Peach D (2006). Renewed
acceleration of the 24°N
jet on Jupiter. Icarus 184, 452-459.
For subscribers, the article is available online via the following link:
http://dx.doi.org/10.1016/j.icarus.2006.05.007
PDF here: Rogers JH, Mettig H-J, and Peach D (2006). Renewed acceleration of the 24°N jet on Jupiter. Icarus (in press).
Summary:
Jupiter's
eastward jet at 24°N, which
formerly had the fastest winds on the planet, has maintained a less
extreme speed of ~135 m/s since 1991, carrying a series of long-lived vortices
at 125 m/s. In 2002-2003, as the
albedo of the adjacent North Temperate Belt increased, the tracks of the
vortices accelerated slightly, and they had disappeared by 2005.
In 2005, small tracers had a mean speed of 146.4 (+/- 0.9) m/s,
significantly faster than the previous mean speed of the jet, suggesting that
the jet peak itself has accelerated at cloud-top level, and that the jet is
beginning to return to the super-fast state.
These changes may resemble the even greater transformations occurring in
the equatorial jet of Saturn.
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Rogers JH, Mettig H-J, Cidadão A, Sherrod PC, and Peach D (2006). Merging circulations on Jupiter: observed differences between cyclonic and anticyclonic mergers. Icarus 185, 244-257.
PDF
here: Rogers
JH, Mettig H-J, Cidadão
A, Sherrod PC, and Peach D (2006). Merging circulations on Jupiter: observed
differences between cyclonic and anticyclonic mergers.
Icarus (in press).
Summary:
The
dynamics of mergers of large circulations in Jupiter's atmosphere may permit
different models of the atmosphere to be tested.
We report well-resolved observations of such events at visible
wavelengths: three anticyclonic and three cyclonic events.
A merger of anticyclonic white ovals in the South South Temperate domain
(2002 March) is compared with the previously reported merger of ovals BE and FA
in the South Temperate domain (2000 March).
In each case, the two similar-sized ovals converged rapidly once they
were separated by less than the sum of their diameters; they orbited around each
other anticyclonically during the merger; the merged oval initially had the same
rapid drift as the western parent; and, in an unexpected similarity, a cyclonic
oval emerged westward from the point of merger.
Evidence suggests that a merger of smaller ovals in the North North
Temperate domain (2002 February) had similar dynamics.
In contrast, mergers of cyclonic ovals in the North Equatorial Belt
('barges': 2001 November, 2005 May) proceeded in a different manner.
The two parent barges showed no consistent acceleration towards each
other as they converged; on contact there was no obvious sign of mutual
circulation, and the low-albedo regions had almost passed each other before they
finally merged; and the resulting barge had a drift rate intermediate between
the two parents, and a length that was greater than either parent.
Again, a third such event involving a smaller barge (2002 December)
showed many of the same characteristics. These
observations define different dynamical behaviour during anticyclonic and
cyclonic mergers.
For subscribers, the article
is available online via the following link:
http://dx.doi.org/10.1016/j.icarus.2006.05.022
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