  The circulation in Europa's ocean determines the degree of thermal,
mechanical and chemical coupling between the ice shell and the silicate mantle.
Using global direct numerical simulations, we investigate the effect of
heterogeneous tidal heating in the silicate mantle on rotating thermal
convection in the ocean and its consequences on ice shell thickness. Under the
assumption of no salinity or ocean-ice shell feedbacks, we show that convection
largely transposes the latitudinal variations of tidal heating from the
seafloor to the ice, leading to a higher oceanic heat flux in polar regions.
Longitudinal variations are efficiently transferred when boundary-driven
thermal winds develop, but are reduced in the presence of strong zonal flows
and may vanish in planetary regimes. If spatially homogeneous radiogenic
heating is dominant in the silicate mantle, the ocean's contribution to ice
shell thickness variations is negligible compared to tidal heating within the
ice. If tidal heating is instead dominant in the mantle, the situation is
reversed and the ocean controls the pole-to-equator thickness contrast, as well
as possible longitudinal variations.
