[8] Interacting spots in the NEB  (report, 2006 June 7)

Billowing clouds in the NEB:

Attached is a set of images showing spot interactions in the NEB in considerable detail.  On May 24 Chris Go pointed out a small, very bright spot in southern NEB (marked with red arrow), just Nf. a dark NEBs projection (marked with red V).  This bright spot is presumably a convective plume, possibly a thunderstorm.  The development of this spot is perhaps not spectacular or unusual, but it may be a well-observed example of an interesting phenomenon. Would you like to look for other possible examples, in your own or other observers' images?

Through the sequence you can see how the NEBs projection drifts faster than the arrowed spot, which in turn drifts faster than NEBn features such as white spot Z. There is also complex rift activity around white spot Z.

The arrowed spot was visible, but very small, before it passed the NEBs projection; then it suddenly brightened; then it doubled; and then it merged with the EZn, creating a bright notch in the NEBs edge. I wonder if this behaviour is common:

1) do other such spots erupt as they pass NEBs projections?

2) do they commonly merge with the EZn to take the place of white plumes f. the NEBs projections? 

I have never looked systematically, but recall seeing an example in the Voyager imagery (see Figs. 8.2 and 9.2 in my book); and watching the Cassini movies, I have the impression that behaviour (1) may be common.

Also, recall that NEBs dark projections sometimes get larger or darker (or are disrupted) as they pass NEB rifts.  You could look for such interactions happening now.

JUPOS charts of NEBn: White spot Z about to merge! 

Here is a JUPOS chart of the barges and white ovals in the northern half of the NEB, prepared by Hans-Joerg Mettig and colleagues.  You can see how some of the barges and white ovals have probably persisted since last apparition, whereas a large sector of them has been wiped out by the advance of White Spot Z (WSZ), with new ones being created in its wake. 

WSZ is presently moving at about -15 deg/mth, which I think must be its fastest speed ever in its 9-year history. WSZ (on NEBn at L2 ~ 220) may be about to merge with the white oval p. it.

Please observe this intensively!

Spots in the N. N. Temperate region:

While watching oval BA approaching the GRS, please also keep an eye on that dark spot in NNTB due N of it, which I predict will vanish in a puff of red smoke soon.

There are dark spots prograding in the NNTBs jetstream.

John Rogers, 2006 June 7