Convection in Europa's ocean subject to tidal heating from the mantle

Several icy moons of Jupiter and Saturn, including Europa and Enceladus, host liquid oceans buried beneath their icy crusts. Geological features of the ice crusts as well as large-scale variations of the ice thickness are often attributed to endogenic processes within the ice. However, the ice crust is also coupled to the rocky interior via the convective ocean which controls heat and material exchanges. Using direct numerical simulations in rotating spherical shells, we investigate how tidal heating within the silicate mantle could affect rotating thermal convection in Europa’s ocean. In particular, tidal heating in the rocky mantle is spatially heterogeneous (larger at the poles, with longitudinal variations of order 2 in the equatorial region). These horizontal variations can drive “thermal winds” which would significantly change the general circulation in the ocean compared with homogeneous heating, which is more representative of radiogenic heating. These results suggest that if tidal heating is dominant in the silicate mantle, its pattern could be partially transposed up to the ice despite the dynamic ocean lying between the ice crust and the rocky mantle.