[1] Jupiter in 2012/13: Jupiter reappears with major outbreaks on NEB and NTB
2012/13
report no.1:
Jupiter
reappears with major outbreaks on NEB and NTB
John
Rogers (BAA), 2012 June 27
Just
before Jupiter disappeared behind the Sun, two very important disturbances
erupted in the North Equatorial Belt and North Temperate Belt.
Both belts had faded (lightened) during 2011, and were very quiet.
The NEB was exceptionally narrow and its south edge devoid of major
features, a state not seen since about a century ago.
The
NEB outbreak [ref.1] began on March 8 when a bright ‘rift’ appeared and
started to generate very dark, slow-moving formations on the NEBs edge.
It seemed possible that this would be the start of a new NEB broadening
event (last seen in 2009), and perhaps of a fully-fledged ‘NEB Revival’ such
as used to happen a century ago. The
NTB outbreak [ref.2] was first detected on April 19 with a very bright and very
dark spot on the NTBs edge. It
seemed likely that this was the start of a new NTBs jet-stream outbreak (last
seen in 2007). Both events would be
spectacular, and important for establishing the long-term patterns of activity
in Jupiter’s atmosphere, so it was frustrating that Jupiter then disappeared
behind the Sun. So we eagerly
awaited the new apparition to find out how the phenomena developed.
Manos
Kardasis in Greece, having discovered the NTBs outbreak in some of the very last
images of the last apparition, also made the first image of the new apparition
on June 4, which confirmed that both outbreaks had developed impressively. He
has posted a map made from his near-infrared (IR) images on June 4-9 [refs.3,4].
Other observers have also made great efforts to get images, in daylight
or at low altitude, and although many of the images inevitably have poor
resolution and quality, they are invaluable for revealing the progress of these
spectacular and rapidly-evolving disturbances. These
images provide strong evidence that a NTBs super-fast outbreak has indeed
occurred, and that a NEB Revival is probably underway.
There are striking dark spots in NTropZ and on NEBs, and reddish or ochre
colour appears to cover much of the NEB, NTropZ, and NTB(S).
Compilations of the images from 2012 June 13-24:
Fig. 1. Set of colour images, arranged by L2. The resolution is inevitably low, and therefore the colours should be interpreted with caution; low resolution, esp. in blue light, can cause reddish colour to spread from belts to zones. Apparent colours also vary depending on the selectivity of the blue filter used, and depending on the processing. South is up.
Fig.2. Set of IR or red-light images, arranged by L2, with major features indicated by colour-coded arrows. These images give better resolution, and show the dark grey spots clearly, but they fail to show the extensive reddish areas, so RGB images are also needed. (Also compare with Kardasis’ earlier map [ref.3].)
Fig.3. Set of the same images, arranged by L1, with major dark formations on NEBs indicated by numbers (and one very bright spot arrowed). The numbering is tentative (and has a break in a poorly-observed sector); these identifications need to be checked by measuring longitudes.
Fig.4.
Previous maps of the NEB and NTB for comparison.
(a)
NEB Revival on 1893 Oct.19-20,
possibly similar to its state in mid-June, 2012.
(b)
NTB outbreak on 2007 April 3, similar to its state when first observed on
2012 April 19.
(c)
NTB Revival on 2007 May 21-22, similar to its state in mid-June, 2012.
(Further
captions and credits are on the images.)
Tentative
descriptions and interpretations:
NTZ:
This is broad and white. Perhaps
the NNTB has whitened as compensation for the darkening of the NTB?
NTB:
The NTB(S) has revived as a dark orange-brown belt around most of the
circumference. This colour is typical after a super-fast outbreak.
From L2 ~ 210-310, it has not yet revived but comprises dark and bright
spots – probably the tail end of the super-fast outbreak, though we have still
not been able to measure any drift rates. (See
comparison map in 2007 May, at a similar time after the start of the outbreak,
which matches the present state well.) Also
from L2 ~ 210-310, a separate dark grey NTB(N) is visible; it may also be
present elsewhere though narrower. (In
IR images, only this N component is visible.)
NTropZ:
This zone has an ochre tint in many images – less so in Akutsu’s,
perhaps because he has higher resolution or a different filter set. The colour
may vary with longitude but it certainly varies with the observer. Future
images should show whether the colour has really diffused across the NTropZ from
the outbreaks, or whether it only appears to do so due to low resolution (which
might also apply to historical obs’ns). Anyway,
this tint has been recorded in some previous years, probably always associated
with a NTBs outbreak and/or a NEB Revival [ref.5].
It is particularly reminiscent of 1985, another year when a strong
reddish colour in the NTropZ gave evidence that the NTB had undergone a
super-fast outbreak during solar conjunction, maintaining a 5-year periodicity.
There
are four very dark grey spots, roughly stationary at L2 = 109, 219, 274, and 359
(a long bar) (all arrowed in the image set). These are very unusual for the
NTropZ, as it is anticyclonic, but similar spots have been seen during previous
NEB broadenings or revivals. (One example is in the comparison map from 1893.) The
very dark spot at L2=277 has persisted from June 6-24, but the one at L2=109
(June 9-18) had N and S components on June 19 (Peach, hi-res) which had sheared
apart on June 20 (Go, hi-res). So
these spots may not be long-lived.
NEB:
The appearance is bizarre, but entirely consistent with an on-going NEB
Revival, as shown in the map from 1893 (adapted from [ref.5].)
The
most remarkable sector is from L2 ~ 50-130, which is very pale, but happened to
be captured in hi-res images on June 19-20 by
Peach, Go, & Akutsu, which showed it to be filled with complex light spots
and streaks. I suspect that this is
an intensely convective ‘rifted’ region comprising the source of the
outbreak. As sketched on the 1893
map, it would be generating dark material f. it on the NEBn (possibly
retrograding?), and intensifying the dark blue-grey ‘projections’ on the
NEBs prograding past it.
At
most other longitudes, IR images show only the narrow NEB(S).
The northern half of the belt is pale and ochre-coloured, possibly not
yet much changed by the outbreak.
The
IR images in Fig.3 show the NEBs ‘projections’.
Typical dark grey or bluish-grey NEBs formations are seen at most
longitudes, moving approx. with System I (L1).
Some are very intense, and may be the same very dark ones that were seen
to appear at the start of the outbreak. I
suspect that these are a series generated as the NEBs flowed past the rifted
region, as we saw commencing in March. The leading projections have now spread
all around the planet, while the trailing ones (nos.10 & 11) are still being
formed.
EZ:
NEBs projections nos.13-14 are embedded in a rare brown sector of EZ(N),
~25 deg. long. There is also a broad brownish Eq. Band at some longitudes,
perhaps indicating the onset of a coloration event, as in 2006-07.
The EZ(S) is still white.
SEB:
The SEB is generally normal, with a typical rifted region f. the GRS, and
dark orange-brown colour over a large part of the belt.
One unusual feature is the cream-coloured spot at L2 = 101, which has
been present there since autumn, 2011, but seems to be bigger and brighter now. Its
nature is a mystery.
STropZ:
The GRS is at L2 = 180. It
still has a dark ring around it, and a dark grey S.Trop.Band p. it, as in 2011.
Oval
BA is approaching the GRS from the f. side, and shows a trace of red colour even
in these lo-res colour images.
References
to our previous bulletins:
[1]
Report no.5. The NEBs
outbreak in 2012 March. (2012 April)
http://alpo-j.asahikawa-med.ac.jp/kk12/j120409r.htm
[Further
images, analysed by G. Adamoli, show that large dark NEBs formations persisted
up to the last useful image on April 25; the leading one maintained its unusual
drift of DL1 = +58 deg/month.]
[2]
Urgent alert for Jupiter observers: Outbreak on NTB. (2012 April 25)
[This original alert was e-mailed and posted
on PVOL
&
Report no.6. Major outbreak
on NTBs jetstream (2012 June)
[An updated version being
posted along with the present report.]
[3]
Jupiter Map, 4-9 June 2012, by
Kardasis.
http://alpo-j.asahikawa-med.ac.jp/kk12/j120609r.htm
[4]
Alert: Major
outbreaks occurring on Jupiter. (2012 June 12)
http://alpo-j.asahikawa-med.ac.jp/kk12/j120612r.htm
[5]
Rogers JH (1995), 'The Giant Planet Jupiter', Chapter 8 (Cambridge
University Press, 1995).
_______________________________
John H. Rogers, Ph.D.
Jupiter Section Director,
British Astronomical Association
John H. Rogers, Ph.D. Jupiter Section Director,
British Astronomical Association
jhr11@cam.ac.uk
http://www.britastro.org/jupiter/