Le séminaire a lieu le Lundi
26 février 2001 de 14h30 à 15h30
dans la salle de réunion
du PHC (Observatoire de Nice).
In this seminar I will present observational and theoretical
aspects
concerning the formation and development of large-scale
storms on the
giant planets. These large-scale storms produce abundant
cloud material on
extensive regions as large as 20.000 km (in the case
of the Saturn Great
White Spots). They evolve quickly in time in a few days
to 1 month and can
change completely the meteorology of the planet across
a whole latitudinal
circle. The study of such features is of great interest
since the modeled
characteristics of these storms are in relation with
meteorological
aspects of the lower troposphere that can not be measured
directly like
the deep abundance of water. At the same time, moist
convective storms may
have a large impact on global properties of the giant
planets like the
vertical transport of the internal heat or even the formation
of
anticyclones.
I will present the results of three-dimensional simulations
of local scale
storms on Jupiter and Saturn that allows studying the
time evolution of
the onset stage of the large-scale storms. The model
is sensible to
several different environment parameters and results
will be presented for
different conditions from the most favorable to the less.
The results
suggest that storms on Jupiter arise on the deep water
clouds while in
Saturn they can originate on the upper ammonia clouds
or on the deep water
clouds, however only intense water storms under very
constrained
conditions can explain the phenomenology of the observed
Saturn Great
White Spots.