  Recent Juno observations have suggested that the heavy elements in Jupiter
could be diluted throughout a large fraction of its gaseous envelope, providing
a stabilising compositional gradient over an extended region of the planet.
This could trigger layered semi-convection, which, in the context of giant
planets more generally, may explain Saturn's luminosity excess and play a role
in causing the abnormally large radii of some hot Jupiters. In giant planet
interiors, it could take the form of density staircases, which are convective
layers separated by thin stably stratified interfaces. In addition, the
efficiency of tidal dissipation is known to depend strongly on the planetary
internal structure. We aim to study the resulting tidal dissipation when
internal waves are excited in a region of layered semi-convection by tidal
gravitational forcing due to other bodies (such as moons in giant planet
systems, or stars in hot Jupiter systems). We adopt a local Cartesian model
with a background layered density profile subjected to an imposed tidal
forcing, and we compute the viscous and thermal dissipation rates numerically.
We find that the rates of tidal dissipation can be enhanced in a region of
layered semi-convection compared to a uniformly convective medium, where the
latter corresponds with the usual assumption adopted in giant planet interior
models. In particular, a region of layered semi-convection possesses a richer
set of resonances, allowing enhanced dissipation for a wider range of tidal
frequencies. The details of these results significantly depend on the
structural properties of the layered semi-convective regions. Layered
semi-convection could contribute towards explaining the high tidal dissipation
rates observed in Jupiter and Saturn, which have not yet been fully explained
by theory. Further work is required to explore the efficiency of this mechanism
in global models.

Earth and Planetary Astrophysics