Europa's dynamic ocean: Taylor columns, eddies, convection, ice melting and salinity

The deep ocean (~100 km) of Europa, Jupiter’s moon, is covered by a thick (tens of km) icy shell, and is one of the most probable places in the solar sys- tem to find extraterrestrial life. Yet, its ocean dynamics and its interaction with the ice cover have so far received little attention. Previous studies sug- gested that Europa’s ocean is turbulent, yet neglected to take into account the effects of ocean salinity and appropriate boundary conditions for the ocean’s temperature. Here, the ocean dynamics of Europa is studied using global ocean models that include non-hydrostatic effects, a full Coriolis force, con- sistent top and bottom heating boundary conditions, and including the effects of melting and freezing of ice on salinity. The density is found to be dominated by salinity effects and the ocean is very weakly stratified. The ocean exhibits strong transient vertical convection, eddies, low latitude zonal jets and Tay- lor columns parallel to Europa’s axis of rotation. In the equatorial region, the Taylor columns do not intersect the ocean bottom and propagate equatorward, while off the equator, the Taylor columns are static. The meridional oceanic heat transport is intense enough to result in a nearly uniform ice thickness, that is expected to be observable in future missions.