EPSS Colloquium spring-2019

The outer solar system is host to a large number of diverse satellites, many of which likely have global oceans beneath their outer icy shells. While the anticipated presence of a global liquid water ocean makes these bodies compelling astrobiological targets, ocean dynamics also play a role in promoting habitable environments. Focusing on Enceladus, Titan, Europa, and Ganymede, I use rotating convection theory and numerical simulations to predict ocean currents and the potential for ice-ocean coupling. When the influence of rotation is relatively strong, the oceans have multiple zonal jets, axial convective motions, and most efficient heat transfer at high latitudes. This regime is most relevant to Enceladus and possibly to Titan, and may help explain their long-wavelength topography. For a more moderate rotational influence, fewer zonal jets form, Hadley-like circulation cells develop, and heat flux peaks near the equator. This regime is predicted for Europa and is possible for Titan, and may help drive geologic activity via thermocompositional diapirism in the ice shell. Weak rotational influence allows concentric zonal flows and overturning cells with no preferred orientation. Predictions for Ganymede's ocean span all of these regimes.