MODELING THE DYNAMICS OF ICY SATELLITE SUBSURFACE OCEANS WITH FOCUS ON

Introduction: Observations from the Galileo and Cassini spacecraft suggest that subsurface global water oceans are likely present on multiple icy satellites of Jupiter and Saturn. With the exception of Titan, the main evidence for satellite subsurface oceans arises from the induction signature generated by the presence of a conductor (presumably a saline ocean) in a timevarying magnetic field [1]. With flyby measurements alone, it is difficult to characterize the subsurface oceans further. The effect of tides on the icy satellites have been studied extensively in the context of tidal heating in the ice shell [2,3]. However, the effect of a time-varying tidal potential on the behavior of the ocean underneath the ice shell has been looked at only in limited contexts [4]. We have modeled the large-scale ocean behavior subject to a time-varying tidal potential in 2-D using classical nonlinear shallow water theory [5] and in 3-D using a numerical magnetohydrodynamics code [6]. We analyze the results of these models in the context of spacecraft observables: the spatial and temporal variation in the magnetic and gravitational fields, and variability in ice shell rotation. Models: Numerical 3-D MHD model. We employ a model that solves a coupled nonlinear system of equations that describes conservation of mass, momentum and energy and the induction of the magnetic field. While there is the ability to account for density stratification, we have presently made the Boussinesq approximation in the model. We calculate the 3-D time-dependent fluid velocity, magnetic field, density, pressure and temperature within the ocean. This solution provides the ability to analyze the aforementioned fields both spatially and temporally. Characteristics of subsurface oceans are currently