The North Tropical Region generally extends from 23° North to 9° North latitude. The north tropical region of Jupiter displays some of the most active and vivid — q q features of the planet. In my experience, more amateur observations are made of this g C
region than any other, rivaled only by the region of the Great Red Spot (GRS). Jfl g —
The north tropical zone (NTrz) lies between the NTB and the north equatorial q ^
belt (NEB). This zone usually exhibits a bright, alabaster appearance, very similar & <D
in brightness to the usual bright appearance of the equatorial zone (EZ.) This <D ^
was the case during the 2000-2001 and 2001-2002 apparitions. However, during |£ ^
2003 the NTrZ was brighter than the EZ, due to the coloration event in the EZ. By March 2004, disturbances in the EZ continued to make the EZ dimmer than the NTrZ. Often, low projections can be seen on the southern edge of the NTB (NTBs) extending into the NTrZ. Several dark projections were seen during the 2000-2001 and 2001-2002 apparitions and were followed reliably for several months, yielding good drift rate data. During 2006, the NTrZ was again one of the brightest zones on the planet, brighter than the EZ and absent any notable features.
The North Tropical Current (NTC) controls all the visible features in the NTrZ and the northern edge of the North Equatorial Belt (NEBn). Although there are variations in the speed of the current, it applies to all major spots whether bright or dark .
Sometimes a thin bluish band can be seen running through the NTrZ longitudinally. This North Tropical Band is not easily seen visually, but was present during the 2002-2003 and 2003-2004 apparitions as revealed by CCD images (Fig. 3.6). Even in the CCD images, the band was very subtle and not visible the entire apparition. This band has come and gone several times during Jupiter's recent history. It was evident during 2006, spanning the circumference of the planet.
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