Jupiter cloud structure from Galileo images: Local cloud systems
D.J. Banfield, M. Bell, P.J. Gierasch, E.A. Ustinov (Cornell), A. Vasavada, A.P. Ingersoll (Caltech), M.J.S. Belton (NOAO), Galileo Imaging Team
A great deal of small scale cloud activity has been observed in
Galileo images. The images were taken in two methane bands
and a nearby continuum, have a horizontal resolution of about 30 km,
and are time lapsed with separations of about 1 hour or 10 hours.
One class of small scale activity is typified by clusters of
optically thick clouds that cover an area several hundred km
across, and have cloud elevation variations of several 10's of
km. In one case northwest of the Great Red Spot, the base of
the system is at a pressure level exceeding 5 bars, pointing
to water as the condensate. These sytems show significant
structural evolution during one hour. Another class of
system are linear cloud striations, sometimes arranged in
parallel rows with separations of a few hundred km. The
linear striation is often made up of a series of small puffs,
each a few 10's of km in diameter. The height of these systems
is about 10 km and they occur at a pressure level of
approximately 1 bar. It is speculated that they are ammonia
condensation triggered by symmetric instability, and that they
are diagnostic of strong vertical shear and low static stability.
We have found this type of system to the northeast of the GRS and
to the southwest of the observed hotspot.