  The Cassini mission unveiled the intense and diverse activity in Saturn's
atmosphere: banded jets, waves, vortices, equatorial oscillations. To set the
path towards a better understanding of those phenomena, we performed
high-resolution multi-annual numerical simulations of Saturn's atmospheric
dynamics. We built a new Global Climate Model [GCM] for Saturn, named the
Saturn DYNAMICO GCM, by combining a radiative-seasonal model tailored for
Saturn to a hydrodynamical solver based on an icosahedral grid suitable for
massively-parallel architectures. The impact of numerical dissipation, and the
conservation of angular momentum, are examined in the model before a reference
simulation employing the Saturn DYNAMICO GCM with a $1/2^{\circ}$
latitude-longitude resolution is considered for analysis. Mid-latitude banded
jets showing similarity with observations are reproduced by our model. Those
jets are accelerated and maintained by eddy momentum transfers to the mean
flow, with the magnitude of momentum fluxes compliant with the observed values.
The eddy activity is not regularly distributed with time, but appears as
bursts; both barotropic and baroclinic instabilities could play a role in the
eddy activity. The steady-state latitude of occurrence of jets is controlled by
poleward migration during the spin-up of our model. At the equator, a
weakly-superrotating tropospheric jet and vertically-stacked alternating
stratospheric jets are obtained in our GCM simulations. The model produces
Yanai (Rossby-gravity), Rossby and Kelvin waves at the equator, as well as
extratropical Rossby waves, and large-scale vortices in polar regions.
Challenges remain to reproduce Saturn's powerful superrotating jet and
hexagon-shaped circumpolar jet in the troposphere, and downward-propagating
equatorial oscillation in the stratosphere.
