The South Equatorial Belt (SEB) of Jupiter is known to alternate its appearance at visible wavelengths
from a classical belt-like band most of the time to a short-lived zone-like aspect which is called a ‘‘fade’’
of the belt, hereafter SEBF. The albedo change of the SEB is due to a change in the structure and properties
of the clouds and upper hazes. Recent works based on infrared observations of the last SEBF have shown
that the aerosol density below 1 bar increased in parallel with the reflectivity change. However, the nature
of the change in the upper clouds and hazes that produces the visible reflectivity change and whether
or not this reflectivity change is accompanied by a change in the winds at the upper cloud level remained
unknown. In this paper we focus in the near ultraviolet to near infrared reflected sunlight (255–953 nm)
to address these two issues. We characterize the vertical cloud structure above the ammonia
condensation level from Hubble Space Telescope images, and the zonal wind velocities from long-term
high-quality images coming from the International Outer Planet Watch database, both during the SEB
and SEBF phases. We show that reflectivity changes do not happen simultaneously in this wavelength
range, but they start earlier in the most deep-sensing filters and end in 2010 with just minor changes
in those sensing the highest particle layers. Our models require a substantial increase of the optical thickness
of the cloud deck at 1.0 ± 0.4 bar from scloud = 6 ± 2 in July 2009 (SEB phase) to semiinfinite at visual
wavelengths in 2010 (SEBF). Upper tropospheric particles (240–1400 mbar) are also required to become
substantially reflectant and their single scattering albedo in the blue changes from -0 = 0.905 ± 0.005 in
November 2009 to -0 = 0.95 ± 0.01 in June 2010. No significant changes were found in the cloud top
heights or in the particle density of the tropospheric haze. The disturbance travels from the levels below
3 bar to a level about 400 ± 100 mbar. We derive an upward velocity of 0.15 ± 0.05 cm/s, in agreement
with a diffusive process in Jupiter’s upper troposphere requiring a mean eddy coefficient
K 8 105 cm2 s1. On the other hand, cloud tracking on the IOPW imaging showed no significant
changes in the zonal wind profile between the SEB and SEBF stages. As in other visually huge changes
in Jupiter’s cloud morphology and structure, the wind profile remains robust, possibly indicating a deeply
rooted dynamical regime.