[8] Jupiter's North Temperate Region in 2009: The nature of the North Temperate Disturbance
by Gianluigi Adamoli (JUPOS team) & John Rogers (BAA.)


The N. Temperate domain in 2009 showed many striking features, including an array of projections from NTBn, some of which developed very dark streaks inside them, and unusual dark spots in the NTZ.  These features have been analysed from the complete JUPOS database.  Most features followed the normal currents in spite of their unusual appearance.  However some of the NTZ spots moved unusually fast, especially in a darkened sector called the N. Temperate Disturbance (NTD).  The NTD was analysed in detail, providing the first full account of its dynamics.  

In its p. half, there were dark cyclonic streaks and bright 'rifts' displaying intense small-scale turbulence. In its f. half, unusual dark anticyclonic spots were appearing in the NTZ and moving with a wide range of speeds.  At least some of these spots resulted from recirculation of spots from the retrograding NTBn jetstream.  The NNTBs jetstream was not deflected and its spots entered the NTD, but they were then intercepted and eliminated by individual spots in the NTZ.  We infer that the NTD is created by conjunction of two phenomena: convective 'rifting' in the NTB, which defines its p. end and leads to disturbance of the retrograding NTBn jetstream; and recirculation at a NTBn projection, which defines the f. end and generates dark spots and streaks in the NTZ.  This is the most detailed analysis yet of a suite of phenomena that have occurred on previous occasions after energetic NTB outbreaks like that of 2007.

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John H. Rogers

Jupiter Section Director,

British Astronomical Association