>From jr@mole.bio.cam.ac.uk Wed Nov 7 04:59 MST 2001 Date: Wed, 7 Nov 2001 11:58:34 +0000 From: John Rogers To: Clay Sherrod cc: Damian Peach , John McAnally , Antonio Cidadao , Isao Miyazaki , Donald Parker , , David M Moore , Hans-Joerg Mettig , Brian Colville , Tomio Akutsu , , , Michel Jacquesson , Maurizio Di Sciullo , Patrick Chevalley , Plinio Camaiti , , , Tan Wei Leong , IJW , Glenn Orton , Francois Colas , Amy Simon , Jean Lecacheux Subject: Re: Barges approaching MIME-Version: 1.0 Hi all, Here are some fuller notes on the features in Jupiter's NEB, as shown in the charts compiled by Hans-Joerg Mettig from various images. A version of the chart is attached as a GIF file. It is in System II; to convert to System III, as of Nov.1, add 60 deg. The NEB is fully broadened to the north and also has the conspicuous red colour that often follows such events. B1-B6 and WS1-WS4 are barges (cyclonic, very dark ovals) and portholes (anticyclonic white ovals) -- a classical array of them presenting in the aftermath of the NEB broadening event. B1, B2, B3: The old barges that have existed since 1997. B2 and B3 are a pair whose separation has varied over the years. B3 was just p. W.S.Z. in 2001 January, as shown beautifully in the Cassini crescent image [and your map projection of it]. B3 has recently shown striking acceleration (bumped by W.S.Z?) and appears slightly south of B2 [Parker image Oct.17; Akutsu image Oct.27]. PERHAPS B3 AND B2 WILL MERGE VERY SOON! B4, B5, B6: Newer barges. We noted B5 and B6 last apparition as newer, smaller, more slowly moving than B1, B2, B3. Now they are just as prominent and moving at the same speed. WS1 (White Spot Z): The famous rapidly-moving white spot that has existed since 1997. It is still a conspicuous 'porthole' and still rapidly moving. WS2, WS3: Newer and smaller portholes. WS4: Another very conspicuous porthole. Although I think it is just a typical white oval, there has been discussion about red colour in this region. It is just Np. barge B1 and there is probably an anticyclonic eddy here [as documented in our reports on NEBn/NTropZ over the last few years]. There was a large diffuse dark reddish patch in this position in summer 2000 (sketched approximately by an orange band on the chart). In the last 2 weeks, Clay Sherrod of the ALPO has noted red colour on or around this oval, especially on a TV monitor, especially when it is near the p.limb; the region of NEBn between WS4 and barge B1 does darken as it nears the limb, according to Sherrod's and Akutsu's images (although the images do not seem to show clearly whether there is any local reddening). Possibly a local reddening effect could be due to the semi-transparent reddish haze that overlies the NEB at present. The System III longitudes of these spots are approximately as follows and they are approximately stationary in System III (to within a few degrees per month): B1, 34; B2, 162; B3, 173; B4, 228; B5, 295; B6, 324; WSZ, 183; WS2, 260; WS3, 305; WS4, 20. John Rogers Jupiter Section Director British Astronomical Association JR@mole.bio.cam.ac.uk 2001 Nov.7 **************************************