Slantwise convection and heat transport in the icy moon oceans

Abstract: Ocean heat transport on icy moons shapes the ice shell topography, a primary observable of these moons. Two key processes control the heat transport: baroclinic instability driven by surface buoyancy contrasts and convective instability driven by heating from the core. However, global ocean simulations cannot accurately resolve convection under realistic icy moon conditions and instead often use Earth-based convective parameterizations, which capture only vertical convective mixing and cannot represent rotation-aligned slantwise convection on icy moons. We use high-resolution convection-resolving simulations to investigate ocean heat transport by slantwise convection in a parameter regime relevant to icy moons, isolated from baroclinic instability. Total heat transport follows the Coriolis-Inertial-Archimedean scaling with an added latitude dependence. The vertical transport increases with latitude, and the meridional transport is poleward. These results indicate that slantwise convection redistributes heat toward the poles, favoring a poleward-thinning ice shell, qualitatively consistent with Enceladus's observed ice thickness distribution.