Cooling patterns in rotating thin spherical shells — Application to Titan's subsurface ocean

Abstract

We use rotating convection simulations in a thin spherical shell to study fluid dynamics in subsurface oceans of icy moons. We find two types of persistent results, characterized by larger outer boundary heat flux either at polar regions or at the equatorial region. Simulations corresponding to larger Rossby numbers result in polar cooling with moderate lateral heterogeneity in heat flux, whereas lower Rossby numbers give equatorial cooling with more pronounced heat flux heterogeneity. The polar cooling scenario is in agreement with inferences for the heat flux at the top of Titan's ocean, which may provide a dynamical constraint for the vigor of convection in this layer. Our results may help unraveling the internal dynamics and the interactions among the different layers within the hydrosphere of Titan. Possible implications for the deep interiors of other icy moons are envisaged.