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[7] Jupiter in 2009: Interim Report, with new insights into the NTZ disturbance, NEB expansion, and SEB fading.

By John H. Rogers (British Astronomical Association), using data from the JUPOS team (Hans-Joerg Mettig & colleagues). 2010 July.

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SUMMARY

This report comprises:

-- A summary of jovian currents and spot motions, as shown in the JUPOS charts for 2009.

-- A summary of the main events on Jupiter from 2009 September (following our last report) to 2010 January (end of the apparition).
-- Preliminary conclusions which may be of general significance, regarding three large-scale phenomena which have been better observed in 2009 than at any previous occurrence:

i) The North Temperate Disturbance: This unusual phenomenon is a dark sector of the NTZ. We show evidence that it develops as a sequel to a vigorous revival of the NTB, and that it is an area of vigorous activity in the NTB and NTZ.

ii) The NEB expansion event: This phenomenon, which currently occurs every 3-5 years, is defined by northwards expansion of the NEB. In 2009 it was accompanied by longitudinal expansion of a very active 'rift' system within the NEB, and also by reappearance of large dark projections on NEBs, which were slow-moving. A partial survey suggests that similar processes occurred during previous NEB expansion events, thus revealing a pattern of disturbance that involves the entire belt.

iii) The SEB fading: This phenomenon began in 2009 very soon after the cessation of 'rift' activity in the SEB, and a series of cyclonic dark ovals quickly appeared in order of increasing longitude, suggesting that there was a reconfiguration of the retrograding SEBs jet.
ACKNOWLEDGEMENTS & DATA ANALYSIS

This is a preliminary report, pending further analysis, but we post it now so as to provide a record of the 2009 apparition, and to discuss some general inferences. This report uses images by numerous observers around the world, especially those whose images are shown by name in the figures (and in our previous interim reports). We are very grateful to all the observers; a full list is posted as Table 1 (List of observers).
Damian Peach produced an exceptionally fine series of images in September, as well as maps from them, and movies of the maps. All are posted on his web site: http://www.damianpeach.com/barbados09.htm

Thanks also to the ALPO-Japan for use of some images posted on their web site. The analysis is based on work by the JUPOS team: Gianluigi Adamoli, Michel Jacquesson, Hans-Joerg Mettig, and Marco Vedovato. They have measured the images using WinJUPOS as usual, and produced charts of longitude vs. time for spots in all latitude ranges. WinJUPOS was created by Grischa Hahn: see http://jupos.org. For the 2009/10 apparition they made a total of 56,492 measurements on images from 77 observers. There were also 811 visual transit measurements of longitude, mainly from Horikawa and Cicognani.

The report also uses cylindrical projection maps of Jupiter, prepared from various observers' images using WinJUPOS by Marco Vedovato, Michel Jacquesson, and Damian Peach.

Drift rates (DL1, DL2: degrees per 30 days in longitude System 1 or 2) are preliminary measurements from JUPOS charts. Latitudes are estimates based on the visibility of spot tracks in JUPOS charts for different latitude ranges. More precise analysis of the JUPOS database remains to be done.
Figures are in the attached ZIP file.