Hi, Jupiter team:
Ovals in the S.S. Temperate region: more mergers?
The attached chart shows the history of white spots in the S.S. Temperate
domain over the past year, and the attached image montage shows their
appearance in the last two months.
A year ago there were 7 small anticyclonic white ovals (AWOs) in the S.S.
Temperate domain at 40-41 deg.S; they have existed for several years and
have gradually bunched together so that they were all within 160 deg.
longitude. I have labelled them as A1 to A7; some of them were separated
by cyclonic white ovals at about 39 deg.S which are labelled C. (There
may have been one or two more, even smaller, spots.) In 2002 March, AWOs
A7 and A6 merged, an event that amateur observers tracked in detail. The
chart suggests that the merged oval merged with A5 in turn, during solar
conjunction, as there are only 5 AWOs now present. A consequence is that
the whole series of ovals is still converging. This sequence of mergers
was strikingly similar to the sequential mergers of similar but larger
white ovals in the S. Temperate domain in recent years - FA with DE and
then with BC. In each case the oval at highest longitude has proceeded to
lower longitudes merging with other ovals in turn.

However oval A3 may also be involved in mergers and hi-res observations of
it would be very worthwhile from now on. (It can be seen in many images
from a year ago as oval A3 was passing the GRS on 2002 Jan.1.) The images
in Oct. and Nov. show A3 to have a variable, lobed structure, as if it
were merging with another white oval. One possibility is that it was
merging with oval A2, and that the oval presently named A2 on the chart is
a new one. In any case, the present oval A2 is rapidly converging on A3
and compressing the cyclonic white oval that lies between them. Possibly
they will rebound (as suggested by the latest image), or possibly they
will merge within the coming weeks, as they pass the GRS.




John Rogers, Hans-Joerg Mettig, Damian Peach.
[British Astronomical Association]

Hi all,
Here is a montage from images over Oct - Dec showing
the fading of the North Temperate Belt

f. the GRS. The faded area spans almost 180 degs, and
also has faded quickly - having almost completely
disappeared in only 3 weeks. Compared to the belts
appearance back in October this certainly represents
quite a major change in its appearance.

It will be interesting to see if the rest of the belt
fades away also.

Best Wishes

Damian Peach.
[Rochester, Kent, UK.]
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