Abstract
The deep (~100 km) ocean of Europa, Jupiter’s moon, covered by a thick icy shell, is one of the most probable places in the solar system to find extraterrestrial life. Yet, its ocean dynamics and its interaction with the ice cover have received little attention. Previous studies suggested that Europa’s ocean is turbulent using a global model and taking into account non-hydrostatic effects and the full Coriolis force. Here we add critical elements, including consistent top and bottom heating boundary conditions and the effects of icy shell melting and freezing on ocean salinity. We find weak stratification that is dominated by salinity variations. The ocean exhibits strong transient convection, eddies, and zonal jets. Transient motions organize in Taylor columns parallel to Europa’s axis of rotation, are static inside of the tangent cylinder and propagate equatorward outside the cylinder. 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.
Highlights
The deep (~100 km) ocean of Europa, Jupiter’s moon, covered by a thick icy shell, is one of the most probable places in the solar system to find extraterrestrial life
We include all components of the Coriolis force, and use the full, non-hydrostatic dynamics
We follow the modern oceanographic literature and use a three equation formulation[30] of the interaction between the icy shell and the ocean temperature and salinity fields, which takes into account the effects of freezing and melting of the icy shell, and diffusion of heat through the ice, on the temperature and salinity
Summary
The deep (~100 km) ocean of Europa, Jupiter’s moon, covered by a thick icy shell, is one of the most probable places in the solar system to find extraterrestrial life. Previous studies suggested that Europa’s ocean is turbulent using a global model and taking into account nonhydrostatic effects and the full Coriolis force. We add critical elements, including consistent top and bottom heating boundary conditions and the effects of icy shell melting and freezing on ocean salinity. The aspect ratio of Europa’s ocean is much higher (~1/16), and the horizontal components of the Coriolis force must be included and have been suggested to result in convection plumes that are parallel to the axis of rotation[20,21,23,25]. Recent studies of Europa’s ocean[23,25] used a global model, taking into account elements such as nonhydrostatic effects and the full Coriolis force, to study the ocean dynamics, and reported a wide low-latitude eastward jet, a high-latitude westward jet, and a rich eddy field. Our resolution is higher than that used previously by an order of magnitude, and the viscosity lower, allowing interesting small scale features to appear
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