[4]
Jupiter
in 2013/14: Interim report no.4
Jupiter
in 2013/14: Interim report no.4
John Rogers (British Astronomical Association), 2013 Dec.21st. (Full size figures below.)
As
Jupiter comes up to opposition on Jan.5, here is a brief review of the
atmospheric features so far, with a set of 4 maps attached (Fig.1).
Many thanks to all the observers, who continue to produce many superb
images, and to the JUPOS team for producing maps and longitude charts.
All longitudes and drift rates are quoted in System II, as of Dec.10
unless otherwise stated. Fig.4
shows a set of recent images: v-hi-res images and methane and UV images, showing
the four anticyclonic reddish ovals as well as other interesting details.
S.S.
Temperate Region:
There
are now ten AWOs forming stable arrays around the circumference.
V-hi-res images have revealed details in the cyclonic regions between
them.
Between
A3 and A4, a cyclonic white oval developed in early Nov., which was reported by
Manos Kardasis on Nov.9 as a methane-bright spot.
This was unusual if not unprecedented, as cyclonic spots are always dark
in methane unless undergoing a vigorous convective outburst; but even more
remarkably, it has remained methane-bright into Dec. (Fig.4).
This perhaps demonstrates what new phenomena can be uncovered now that
image derotation allows observers to obtain such hi-res methane-band images.
Several
SSTBn jet spots have been recorded, mostly prograding up to the dark spots in
STZ Sf. the dark STB segment, where they decelerate and are lost.
One pair prograded up to the STB Ghost (see below), where one
disappeared, while the other reversed its drift to retrograde (with
oscillations) in the STZ (Figs.2
& 3).
S.
Temperate Region:
Oval BA is still strongly orange (with a white centre), and the STB segment f. it is long and dark with internal turbulence in v-hi-res images. Oval BA accelerated greatly during solar conjunction, as predicted [see report, ref.1], and has maintained this high speed of DL2 = -14.3 deg/month. The intense outbreak of dark spots on the STBn prograding jetstream is also continuing.
The
other substantial, though inconspicuous, feature of the S.Temp. domain is the
‘STB Ghost’, a faint oblique structure which has been passing the GRS in
Nov-Dec. SSTBn jet spots were unable
to pass it, one recirculating into STZ (see above).
It is conspicuously methane-dark (Figs.2 and
4). All these characteristics confirm that it is an exact copy of the STB
Remnant from a few years ago.
Thus
the present STB cycle is playing out just as we described for previous cycles,
and is presently in the same state as in 2005 [ref.2].
S.
Tropical Region:
The
GRS is a strongly orange oval, at L2 = 204.
The
STropZ is narrowed by dark grey streaks which occupy most of its northern half,
and recently, light brown shading has also filled the southern half of the zone
p. the GRS.
The
mysterious light yellowish patch in the SEB approached the p. end of the Red
Spot Hollow in August but then halted there.
A bright streak of identical colour developed which appeared to connect
it with the N edge of the Red Spot Hollow, but the oval outline of the light
patch has remained visible in hi-res images, suggesting that it is still a
cyclonic circulation. Consistent
with this, in methane images it is slightly darker than the surrounding SEB (Fig.4).
The
SEB f. the GRS shows intense rifting activity. Sometimes one of the new, bright
white convective plumes is methane-bright. A striking example was noticed on
Oct.8 by M.Delcroix; also caught on Oct.11 by P.Maxson and Oct.13 by C.Pellier (Fig.2).
Another was recorded on Dec.10 by C. Pellier (Fig.4).
Equatorial
Region:
The
NEBs still carries a prominent array of dark bluish ‘projections’, almost
stationary in L1, with elaborate festoons into the EZ.
N.Tropical Region:
The
NEB has narrowed as the NEBn has retreated following last year’s great NEB
Revival. Bright rifts are quite
plentiful within it. With internal convective activity plus prominent
projections along the NEBs edge, I believe the NEB is not yet ready for another
full cycle of fading and revival, but this could change within the next year or
two.
The
NEBn edge is ragged with few prominent features.
Two dark barges
were rapidly converging, partially driven by white spot Z (WSZ) approaching from
the f. side, but they were not seen to merge as the smaller one disappeared just
before they collided. The larger one
soon disappeared as well, as WSZ prograded alongside it. WSZ
has now decelerated to DL2 = -15 deg/month.
WSZ
has attracted attention, first because it had become strikingly methane-bright
by the start of this apparition (and has remained so since), and secondly
because it has developed reddish colour. It
became faintly brownish-grey during the autumn, and on Nov.24 Chris Go reported
that it had become more distinctly reddish in its N half.
This has progressed since so it is now a complete, weakly reddish-grey
oval (which could be called Red Oval Z, as Chris Go has proposed, if it
persists). We have just posted a detailed report on WSZ’s history and
characteristics and recent changes [ref.3].
N.
Temperate Region:
Following
last year’s great NTB Revival, the NTB(S) is bland and pale orange, while the
NTB(N) is dark grey with complex features. The whole N.Temperate domain looks as
it did in 2009, at the same stage of the NTB cycle [ref.4].
A
dark sector of NTZ, from L2 ~260-300, can be called a N.Temperate Disturbance (NTD)
[ref.4], and is probably being generated by turbulent convective activity in a
rifted region p. it. On the maps in Fig.1,
the NTD is labelled along with this rifted region (feature 1).
Another rifted region of NTB (feature 3) also seems to be generating dark
material in the NTZ f. it. Between
them is an array of streaks and ovals, the longest of which (feature 2) was a
very dark grey streak in Aug-Sep., then turned orange-brown in Oct., the faded
until it is now a bright cream-coloured lozenge. This was a classic instance of
a dark cyclonic feature turning red before it fades.
Immediately f. it are a cyclonic white oval and an AWO.
In methane images, the AWO is very weakly methane-bright, the cyclonic
features are not.
N.N.
Temperate Region:
The
NNTBs jet, which revived in late 2012, developed a major outbreak with numerous
dark jetstream spots at all longitudes in 2013 Aug-Sep.
There are now fewer of them. The JUPOS chart shows that no new ones have
been produced since early Oct., while 6-9 of the previous spots
have merged into two large ones. The
two large ones are reddish and methane-bright
(*
on Fig.1), and slower-moving (DL2 ~-67 deg/mth,
as against ~-82 deg/mth for the earlier smaller spots).
Spots like these have been seen before on the NNTBs jet (there was a pair
in the Galileo image of the region, shown in ref.5), but they are not common.
In the NNTZ, NN-LRS-1 [ref.5] (L2 = 156) is still strongly reddish, with a dark brown collar.
Full resolution figures (click image for full res version.)
Figure 01
Figure 03
Figure 04
References
to our previous reports:
[1]
Rogers J (2013). ‘Jupiter in 2013/14: The new apparition begins.’ http://www.britastro.org/jupiter/2013_14report01.htm
[2]
Rogers J, Adamoli G, Hahn G, Jacquesson M, Vedovato M, & Mettig H-J
(2013). ‘Jupiter’s South
Temperate domain: Behaviour of long-lived features and jets, 2001-2012.’
http://www.britastro.org/jupiter/stemp2013.htm
[3]
Rogers J (2013 Dec.) ‘White spot Z: its history and characteristics,
1997-2013.’ http://www.britastro.org/jupiter/2013_14report03.htm
[4]
Adamoli G & Rogers J (2010),
‘Jupiter's
North Temperate Region in 2009: The nature of the North Temperate
Disturbance.’
http://www.britastro.org/jupiter/2009report08.htm
[5]
Rogers JH, Adamoli G & Mettig H-J
(2011 Feb.) JBAA 121 (no.1),
19-29.
‘Jupiter’s
high-latitude storms: A Little Red Spot tracked through a jovian year.’
http://www.britastro.org/jupiter/2012_13/JBAA%202011_NNTZ-ovals_Rogers%20proof2.pdf